+publisher:"University of Michigan" +contributor:("Violi, Angela")

University of Michigan

1. Lin, Kuang-Chuan. Numerical simulations of thermal systems – Applications to fuel chemistry, nanofluid heat transfer and aerosol particle transport.

Degree: PhD, Mechanical engineering, 2011, University of Michigan

URL: http://hdl.handle.net/2027.42/127193

► In this dissertation, three topics in thermal systems are investigated: 1) the effect of methyl-ester content on combustion chemistry of a biodiesel surrogate; 2) the… (more)

▼ In this dissertation, three topics in thermal systems are investigated: 1) the effect of methyl-ester content on combustion chemistry of a biodiesel surrogate; 2) the effects of non-uniform particle sizes and fluid temperature on heat transfer characteristics of liquid water containing alumina nano-particles; 3) the effects of obstacle arrangements on transport of aerosol particles in channel flows. The investigation focuses on computational modeling and analysis in the above problems. In the first study, a kinetic modeling comparison of methyl butanoate and n-butane, its corresponding alkane, contrasts the combustion of methyl esters and normal alkanes, with the aim of understanding the effect of the methyl ester moiety. A fuel-breakdown model [J. Org. Chem. 2008, 73, 94; J. Phys. Chem. A 2008, 112, 51] is added to existing chemical kinetic mechanisms to improve the prediction of CO2 formation from MB decomposition. Sensitivity and reaction pathway analysis show that the absence of negative temperature coefficient behaviors and reduction of soot precursors can be ascribed to the effect of the methyl ester. The second study analyzes the heat transfer and fluid flow of natural convection in a cavity filled with Al₂O₃/water nanofluid that operates within differentially heated walls. The Navier-Stokes and energy equations are solved numerically, coupling the model of effective thermal conductivity [J. Phys. D 2006, 39, 4486] and model of effective dynamic viscosity [Appl. Phys. Lett. 2007, 91, 243112]. The numerical simulations explore the range where the heat transfer uncertainties can be affected by the operating conditions of the nanoparticles. Furthermore, the suppressed heat transfer phenomena are in good agreement with the latest experimental data of Ho et al. [Int. J. Therm. Sci. 2010, 49, 1345]. Finally, by using a simple lattice Boltzmann model coupled with a Lagrangian formalism, this study investigates the dispersion and deposition of aerosol particles over staggered obstacles in a two-dimensional channel flow. Particle motion mechanisms considered in the particle phase equation include drag, gravity, lift and Brownian forces. In this study, the results highlight the range of particle dimensions where the particle deposition can be affected by the arrangement of blocks placed in the channel flow. Advisors/Committee Members: Violi, Angela (advisor).

Subjects/Keywords: Aerosol; Aerosols; Applications; Biodiesel; Chemistry; Fuel; Heat Transfer; Nanofluid; Nanofluids; Numerical; Particle Transport; Simulations; Systems; Thermal

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APA (6^th Edition):

Lin, K. (2011). Numerical simulations of thermal systems – Applications to fuel chemistry, nanofluid heat transfer and aerosol particle transport. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/127193

Chicago Manual of Style (16^th Edition):

Lin, Kuang-Chuan. “Numerical simulations of thermal systems – Applications to fuel chemistry, nanofluid heat transfer and aerosol particle transport.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/127193.

MLA Handbook (7^th Edition):

Lin, Kuang-Chuan. “Numerical simulations of thermal systems – Applications to fuel chemistry, nanofluid heat transfer and aerosol particle transport.” 2011. Web. 10 Apr 2021.

Vancouver:

Lin K. Numerical simulations of thermal systems – Applications to fuel chemistry, nanofluid heat transfer and aerosol particle transport. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/127193.

Council of Science Editors:

Lin K. Numerical simulations of thermal systems – Applications to fuel chemistry, nanofluid heat transfer and aerosol particle transport. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/127193

University of Michigan

2. Ahmad Mahir, Luqman Hakim Bin. Modeling Paraffin Wax Deposition from Flowing Oil onto Cold Surfaces.

Degree: PhD, Chemical Engineering, 2020, University of Michigan

URL: http://hdl.handle.net/2027.42/155131

► Paraffins with large molecular weights precipitate out of solution when temperature decreases, forming a three-dimensional network of crystals that can impede oil flow in a… (more)

▼ Paraffins with large molecular weights precipitate out of solution when temperature decreases, forming a three-dimensional network of crystals that can impede oil flow in a pipe, which is undesirable during crude oil production. One way to assess the potential and severity of a paraffin wax deposition is to employ a first principle mathematical model that can predict the growth rate and evolution of paraffin wax gel or deposit as a function of time. In this thesis, a wax deposition model that includes transient heat transfer and transient mass transfer that are coupled was developed. The model takes the cold finger geometry as a basis and assumes that the heat and mass transfer occur primarily in the radial direction and negligible in other directions while allowing for the possible effects of yield stress on the deposition through a critical solid wax concentration at the deposit-fluid interface, Cpi. This new parameter is the precipitated wax concentration needed to withstand the shear stress imposed by the flow at the interface and reflects the dependence of the deposit yield stress on precipitate concentration and the fluid shear stress at the interface. Wax is taken to be a pseudo one-component that can exist in either a molecular (soluble) or precipitated state. Precipitation is described by a first order reaction where the rate law is given by the product of a rate coefficient and the difference between the local soluble wax concentration and the local solubility limit. Precipitated waxes are assumed to not diffuse and can revert back into soluble waxes if the local soluble wax concentration becomes lower than the local solubility limit. Model predictions were found to be in good agreement with experimental data obtained using a cold finger apparatus. A model oil with a relatively high concentration of wax (in this work composed of 10wt% n-C28 in n-C12), was found able to form gels at a very low precipitated wax concentration where the effect of Cpi is insignificant (close to zero), thus as a result the rate of advancement of the gel-oil interface is dominantly controlled by the heat transfer rate. However, even after reaching a steady-state thickness, n-C28 in the bulk oil continues to diffuse into the gel, densifying the gel. This observation signifies that mass transfer must be taken into account regardless of whether heat or mass transfer is controlling the growth rate. It was also found that after reaching the maximum gel thickness, the gel-oil interface can also retreat back and approaches a new steady-state location which is reached at a much slower rate of days to weeks. This retreat of the front was found to be the result of the depletion of wax in the bulk oil. Experiment performed using a dilute wax model oil (in this work composed of 0.8wt% n-C36 in mineral oil) revealed that its gel growth rate is controlled dominantly by mass transfer. In a dilute wax model oil, the concentration of precipitated waxes is so small that a stable gel is unable to form until mass transfer carrying wax molecules from… Advisors/Committee Members: Fogler, Hugh Scott (committee member), Larson, Ronald G (committee member), Violi, Angela (committee member), Ziff, Robert M (committee member).

Subjects/Keywords: Coupled heat and mass transfer; Paraffin wax gel; Paraffin precipitation; Chemical Engineering; Engineering

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APA (6^th Edition):

Ahmad Mahir, L. H. B. (2020). Modeling Paraffin Wax Deposition from Flowing Oil onto Cold Surfaces. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/155131

Chicago Manual of Style (16^th Edition):

Ahmad Mahir, Luqman Hakim Bin. “Modeling Paraffin Wax Deposition from Flowing Oil onto Cold Surfaces.” 2020. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/155131.

MLA Handbook (7^th Edition):

Ahmad Mahir, Luqman Hakim Bin. “Modeling Paraffin Wax Deposition from Flowing Oil onto Cold Surfaces.” 2020. Web. 10 Apr 2021.

Vancouver:

Ahmad Mahir LHB. Modeling Paraffin Wax Deposition from Flowing Oil onto Cold Surfaces. [Internet] [Doctoral dissertation]. University of Michigan; 2020. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/155131.

Council of Science Editors:

Ahmad Mahir LHB. Modeling Paraffin Wax Deposition from Flowing Oil onto Cold Surfaces. [Doctoral Dissertation]. University of Michigan; 2020. Available from: http://hdl.handle.net/2027.42/155131

3. Kang, Dongil. Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine.

Degree: PhD, Chemical Engineering, 2016, University of Michigan

URL: http://hdl.handle.net/2027.42/133374

► The autoignition characteristics of individual hydrocarbon species studied in motored engine can provide a better understanding of the autoignition process and complex fuels for homogeneous… (more)

▼ The autoignition characteristics of individual hydrocarbon species studied in motored engine can provide a better understanding of the autoignition process and complex fuels for homogeneous spark and compression ignition engines, whether the interest is understanding and preventing knock or controlling autoignition. In both instances, there is a critical need to comprehend how fuel molecular structure either retards or promotes autoignition reactivity. This understanding ultimately contributes to the development of kinetic mechanisms, which are needed for simulation of reacting flows and autoignition processes. For this reason, the dissertation discusses autoignition data on i) three pentane isomers (n-pentane, neo-pentane and iso-pentane), ii) ethyl-cycloahexane and its two isomers (1,3-dimethyl-cyclohexane and 1,2-dimethyl-cyclohexane), and iii) diisobutylene in primary reference fuels. looking for their chemical structural impacts on the ignition process. Particularly for exploring the low and intermediate temperature regions, the motored variable compression ratio engine, developed from a Cooperative Fuel Research (CFR) Octane Rating engine, provided a good platform. Analyses of the stable intermediates in the CFR engine exhaust at various end of compression pressures and temperatures can help to identify reaction pathways through which different compounds prefer to autoignite. The approach of those studies is to conduct a systematic investigation of the autoignition, which can provide useful input for qualitative and semi-quantitative validation of kinetic mechanisms for oxidation of target chemical compounds. Finally, the dissertation is further extended to an experimental validation of jet aviation fuel surrogates, potentially emulating a series of physical and chemical ignition processes in diesel engines, with an emphasis on the needs for detailed auto-ignition characteristics of various individual hydrocarbon species. Advisors/Committee Members: Boehman, Andre L (committee member), Savage, Phillip E (committee member), Violi, Angela (committee member), Schwank, Johannes W (committee member).

Subjects/Keywords: Autoignition process; CFR octane rating engine; hydrocarbon oxidation; Chemical Engineering; Mechanical Engineering; Engineering

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APA (6^th Edition):

Kang, D. (2016). Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/133374

Chicago Manual of Style (16^th Edition):

Kang, Dongil. “Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine.” 2016. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/133374.

MLA Handbook (7^th Edition):

Kang, Dongil. “Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine.” 2016. Web. 10 Apr 2021.

Vancouver:

Kang D. Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2016. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/133374.

Council of Science Editors:

Kang D. Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine. [Doctoral Dissertation]. University of Michigan; 2016. Available from: http://hdl.handle.net/2027.42/133374

4. Paleg, Sarah. Promoting Molybdenum Carbide for Biofuels Upgrading.

Degree: PhD, Chemical Engineering, 2019, University of Michigan

URL: http://hdl.handle.net/2027.42/149846

► Pyrolysis biofuels are an attractive near-term solution for reducing carbon emissions from vehicles including automobiles and jets while still being compatible with current engine technology.… (more)

▼ Pyrolysis biofuels are an attractive near-term solution for reducing carbon emissions from vehicles including automobiles and jets while still being compatible with current engine technology. However, in order to be used as a “drop-in” fuel, bio-oil must be upgraded into biofuel by removing oxygen, increasing hydrocarbon chain lengths, and increasing energy density. Current catalytic processes rely on expensive noble metal catalysts, and/or are not sufficiently selective in their upgrading. Molybdenum carbide (Mo2C) is a low-cost, high surface area catalyst that is known to be active for hydrogenation and other relevant reactions and was identified as a promising candidate for use as a bio-oil upgrading catalyst. The research undertaken in this dissertation aims to investigate methods to control the activity and selectivity of the Mo2C catalyst through adding promoter metals to the surface of the Mo2C catalyst. Model compounds were selected to represent important properties of bio-oil; both acetic acid and crotonaldehyde were used as model compounds. Fe, Co, Ni, Cu, Ru, Rh, Pd, and K were screened as metal promoters of crotonaldehyde conversion. Rh, Pd, and Co did not significantly affect catalyst activity or selectivity. Ni, Cu, and K increased the selectivity to the isomerization product, while Fe increased the selectivity to the HDO products. K showed the highest selectivity to isomerization product, so it was selected for further study. A series of catalysts with increasing amounts of K promotion up to 1.1 equivalent monolayers on Mo2C were synthesized via incipient wetness and tested for their activity and selectivity in acetic acid and crotonaldehyde conversion. K promotion increased selectivity to ketonization and isomerization products, respectively, and reached a maximum effect at 0.5ML. Similarly, K increased base site concentration on the Mo2C surface, and the change in base site concentration as found to correlate with the ketonization and isomerization products’ productivities. Consequently, the base site, thought to be an exposed negatively charged C atom or an Mo-O species, was proposed as the active site for dominant product formation on Mo2C. Additionally, K promotion was found to be an effective tool to control the base site density. In initial screening, Fe showed highest selectivity to HDO products, so it was selected for further study and to compare with K promotion. A series of catalysts with increasing amounts of Fe promotion up to 1.1 equivalent monolayers on Mo2C were synthesized via incipient wetness (because it allowed to higher Fe promotion) and tested for their activity and selectivity in crotonaldehyde conversion. Fe promotion was found to decrease both acid and base site concentrations with more than 0.5ML of Fe, as well as crotonaldehyde conversion rates. Productivity of much products decreased, but correlations between active site concentrations and productivities showed which active site types were most predictive of a given product. The weak base site concentration was found to… Advisors/Committee Members: Thompson, Levi Theodore (committee member), Violi, Angela (committee member), Barteau, Mark A (committee member), Schwank, Johannes W (committee member).

Subjects/Keywords: Mo2C; biofuels; hydrogenation; Chemical Engineering; Engineering

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APA (6^th Edition):

Paleg, S. (2019). Promoting Molybdenum Carbide for Biofuels Upgrading. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/149846

Chicago Manual of Style (16^th Edition):

Paleg, Sarah. “Promoting Molybdenum Carbide for Biofuels Upgrading.” 2019. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/149846.

MLA Handbook (7^th Edition):

Paleg, Sarah. “Promoting Molybdenum Carbide for Biofuels Upgrading.” 2019. Web. 10 Apr 2021.

Vancouver:

Paleg S. Promoting Molybdenum Carbide for Biofuels Upgrading. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/149846.

Council of Science Editors:

Paleg S. Promoting Molybdenum Carbide for Biofuels Upgrading. [Doctoral Dissertation]. University of Michigan; 2019. Available from: http://hdl.handle.net/2027.42/149846

5. Wagnon, Scott William. Chemical Kinetics for Advanced Combustion Strategies.

Degree: PhD, Mechanical Engineering, 2014, University of Michigan

URL: http://hdl.handle.net/2027.42/108943

► This dissertation presents new understanding of the role of fuel chemistry on reaction pathways important to fuel oxidation and ignition at conditions relevant to advanced… (more)

▼ This dissertation presents new understanding of the role of fuel chemistry on reaction pathways important to fuel oxidation and ignition at conditions relevant to advanced combustion strategies. A deeper and quantitative understanding of fuel chemistry effects on combustion behavior can be used to improve modern combustion strategies that operate at low temperature (<1200 K) conditions using conventional or alternative fuels. A comprehensive understanding of the role of fuel chemistry enables high efficiency and low emissions from combustion technologies. This work used experimental and computational studies to understand the impact of fuel chemistry at low temperature conditions that are the focus of modern combustion systems. Optically accessible facilities, including a rapid compression machine and a shock tube, were used to study global and detailed combustion chemistry of several important fuel compounds. The results of the computational study on buffer gas composition effects on fuel ignition indicated that ignition phasing is sensitive to composition effects at low pressures, high levels of dilution, and temperatures corresponding to non-Arrhenius or multi-stage conditions. The results of the work on ignition behavior of methyl trans-3-hexenoate highlighted uncertainties in unsaturated methyl ester reaction chemistry, namely the R+O2 reaction rates and products of smaller unsaturated intermediates. The data presented in the phenyl oxidation study are the first laser schlieren measurements of radical oxidation reactions and the results provide a foundation for further studies which quantify important elementary reaction rates and pathways in oxidation systems, such as phenyl+O2. In the work with the three linear hexene isomers, the length of the alkyl chain was responsible for changes in reactivity, activation energy, and measured differentiation in the formation of stable intermediates at the conditions studied. The results of these studies quantify the reactivity of important fuel compounds, which is particularly vital as fuel feed stocks change and the low temperature operating conditions of modern combustion systems become more reaction limited. The results also inform theory on reaction rate rules for elementary reactions and guide the development of detailed, global, and skeletal reaction mechanisms at low temperatures. Advisors/Committee Members: Wooldridge, Margaret S. (committee member), Gamba, Mirko (committee member), Boehman, Andre L. (committee member), Violi, Angela (committee member), Tranter, Robert S. (committee member).

Subjects/Keywords: Alternative Fuels; Experimental Chemical Kinetics; Low Temperature Combustion; Rapid Compression Facility; Shock Tube; Mechanical Engineering; Engineering

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APA (6^th Edition):

Wagnon, S. W. (2014). Chemical Kinetics for Advanced Combustion Strategies. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/108943

Chicago Manual of Style (16^th Edition):

Wagnon, Scott William. “Chemical Kinetics for Advanced Combustion Strategies.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/108943.

MLA Handbook (7^th Edition):

Wagnon, Scott William. “Chemical Kinetics for Advanced Combustion Strategies.” 2014. Web. 10 Apr 2021.

Vancouver:

Wagnon SW. Chemical Kinetics for Advanced Combustion Strategies. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/108943.

Council of Science Editors:

Wagnon SW. Chemical Kinetics for Advanced Combustion Strategies. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/108943

University of Michigan

6. Chen, Yawei. A Study of Thermal and Catalytic Pyrolysis of Centimeter-scale Biomass Particles.

Degree: PhD, Mechanical Engineering, 2018, University of Michigan

URL: http://hdl.handle.net/2027.42/145968

► Finding renewable alternatives to fossil fuels is one of the most important challenges of the twenty-first century. In this context, biomass is an important source… (more)

▼ Finding renewable alternatives to fossil fuels is one of the most important challenges of the twenty-first century. In this context, biomass is an important source of renewable energy. This thesis concerns the pyrolysis of centimeter-scale biomass particles, a process that is a key step in the thermochemical conversion of biomass resources to biofuels. Biomass particles commonly have irregular shapes and sizes, which are critical parameters affecting heat and mass transfer rates during the pyrolysis process. To investigate the pyrolysis behavior of biomass particles of various shapes and sizes, a mathematical model was introduced and numerically solved to simulate the complex physical and chemical reactions during biomass pyrolysis. Prolate and oblate ellipsoids were chosen to represent the biomass particles of arbitrary and irregular geometries. Numerical simulations were validated against relevant literature and experimental data. The effect of the particle shapes and sizes on the mass loss, center temperature, pyrolysis duration, and the product yields were investigated. In this study, the bio-oil directly produced from the pyrolysis of centimeter-scale biomass particles contains a large number of oxygenated compounds and does not have any hydrocarbon compounds. In order to improve the bio-oil quality, both the pre-treatment of the biomass and post-treatment of the pyrolysis vapors were investigated respectively in a fixed-bed furnace reactor. Torrefaction is the thermal treatment of biomass particle before they are pyrolyzed. To investigate the effect of torrefaction temperature and time on wood pyrolysis, centimeter-scale pine wood particles were first torrefied at 225 °C, 250 °C, 275 °C, and 300 °C for 15 min, 25 min, and 35 min. Then the torrefied wood particles were used as the feedstock for pyrolysis. Pyrolysis yields of liquid, gas, and char were calculated and found to be affected by the torrefaction conditions. The temperature profiles in the center of the particles were measured and, both the endothermic and exothermic reactions were observed and explained. Chemical analysis of bio-oil obtained from torrefied wood showed that no hydrocarbon species were detected after torrefaction treatment. Zeolite cracking is a post-treatment technique of the pyrolysis vapor in a high-temperature catalyst environment. Pine wood particles were pyrolyzed in a vertical tube furnace at 500 °C followed by the upgradation of pyrolysis vapors using zeolite ZSM-5 at catalyst temperatures of 400-600 °C (steps of 50 °C). The catalyst was later regenerated to recover its acidity and activity. Pyrolysis oil collected before and after catalysis was characterized by measuring the yield, the water content, and the chemical composition of its organic content. The pyrolysis oil before catalysis was homogeneous and highly oxygenated and neither aromatic nor polycyclic aromatic hydrocarbons (PAH) were detected. Upon catalytic treatment, the yield of bio-oil was markedly reduced from 56.32% to 43.69% (catalyst temperature: 400 °C),… Advisors/Committee Members: Atreya, Arvind (committee member), Schwank, Johannes W (committee member), Violi, Angela (committee member), Wooldridge, Margaret S (committee member).

Subjects/Keywords: biomass pyrolysis; centimeter-scale biomass; catalytic pyrolysis; biofuel; Chemical Engineering; Mechanical Engineering; Engineering

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APA (6^th Edition):

Chen, Y. (2018). A Study of Thermal and Catalytic Pyrolysis of Centimeter-scale Biomass Particles. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/145968

Chicago Manual of Style (16^th Edition):

Chen, Yawei. “A Study of Thermal and Catalytic Pyrolysis of Centimeter-scale Biomass Particles.” 2018. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/145968.

MLA Handbook (7^th Edition):

Chen, Yawei. “A Study of Thermal and Catalytic Pyrolysis of Centimeter-scale Biomass Particles.” 2018. Web. 10 Apr 2021.

Vancouver:

Chen Y. A Study of Thermal and Catalytic Pyrolysis of Centimeter-scale Biomass Particles. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/145968.

Council of Science Editors:

Chen Y. A Study of Thermal and Catalytic Pyrolysis of Centimeter-scale Biomass Particles. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/145968

University of Michigan

7. Pinnarat, Tanawan. Noncatalytic Esterification for Biodiesel Production.

Degree: PhD, Chemical Engineering, 2011, University of Michigan

URL: http://hdl.handle.net/2027.42/89765

► Noncatalytic esterfication of fatty acids is an alternative process for biodiesel production. This thesis showed the possibility of conducting the esterification of oleic acid under… (more)

Subjects/Keywords: Noncatalytic Esterification; Noncatalytic Biodiesel Production; Kinetics of Esterification; Mechanism of Esterification; Biodiesel from Algae; Chemical Engineering; Engineering

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APA (6^th Edition):

Pinnarat, T. (2011). Noncatalytic Esterification for Biodiesel Production. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/89765

Chicago Manual of Style (16^th Edition):

Pinnarat, Tanawan. “Noncatalytic Esterification for Biodiesel Production.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/89765.

MLA Handbook (7^th Edition):

Pinnarat, Tanawan. “Noncatalytic Esterification for Biodiesel Production.” 2011. Web. 10 Apr 2021.

Vancouver:

Pinnarat T. Noncatalytic Esterification for Biodiesel Production. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/89765.

Council of Science Editors:

Pinnarat T. Noncatalytic Esterification for Biodiesel Production. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/89765

University of Michigan

8. Schwind, Rachel. Understanding the Combustion Chemistry of Siloxanes: Reaction Kinetics and Fuel Interactions.

Degree: PhD, Mechanical Engineering, 2019, University of Michigan

URL: http://hdl.handle.net/2027.42/153412

► This work explores the reaction kinetics of three complimentary organosilicon structures important to waste-to-energy and material synthesis applications. The chemical kinetics of the siloxane compounds… (more)

▼ This work explores the reaction kinetics of three complimentary organosilicon structures important to waste-to-energy and material synthesis applications. The chemical kinetics of the siloxane compounds were investigated using oxidation/auto-ignition and pyrolysis/thermal decomposition experiments. The twofold approach enabled a large range of state conditions and reaction chemistries to be studied, often for the first time. The effects of trimethylsilanol (TMSO) and hexamethyldisiloxane (HMDSO) on syngas (H2 and CO) auto-ignition behavior at temperatures of 1010 – 1070 K and pressures of 8 to 10.3 atm were quantified using a rapid compression facility (RCF). Trace concentrations of TMSO (100 ppm, mole basis) and HMDSO (100 ppm) were added to a surrogate syngas mixture of CO and H2 (with a molar ratio of 2.34:1), air levels of dilution, with molar equivalence ratio of ϕ = 0.1). The measured ignition delay times showed both siloxane species dramatically promoted reactivity of the H2 and CO reactants as indicated by reduced ignition delay times, with TMSO decreasing ignition delay times by approximately 37% and HMDSO decreasing ignition delay times by approximately 50% compared with the reference syngas mixture which contained no siloxanes. HMDSO also demonstrated a marked increase in energy release with an increase in pressure rise of approximately 20% compared with the reference syngas mixture. The thermal decomposition behavior of three organosilicon species, TMSO, HMDSO and hexamethylcyclotrisiloxane (HMCTSO), was investigated using two shocktube facilities: a diaphragmless shocktube (DFST) and a unique high-repetition rate shocktube (HRRST). This work provided first-of-their-kind laser schlieren densitometry results for understanding the thermal effects of the decomposition process. All three siloxane compounds demonstrated strongly endothermic behavior. Time-resolved speciation data were also obtained during the pyrolysis experiments using time-of-flight mass spectrometry (TOF-MS). The first-of-their-kind data provided vital new information at conditions not studied previously. Additionally, TOF-MS experiments using photo-ionization energy from a synchrotron facility provided further insights into the species relevant for thermal decomposition. The data showed the HMDSO, TMSO and HMCTSO do not decompose into smaller silicon based intermediates, as expected based on the limited information on these species available in the literature. Instead, small hydrocarbons were observed as were spectra attributable to larger stable siloxane species. The results of the oxidation and thermal decomposition experimental studies were used to propose and test hypotheses for siloxane reaction pathways important for this class of compounds. Importantly, the experimental data indicate significant reactivity at combustion conditions which may be attributed, in part, to increased production of the OH radical pool. However, the results also indicate direct reactions with the siloxane compounds or silicon-containing… Advisors/Committee Members: Wooldridge, Margaret S (committee member), Schwank, Johann W (committee member), Tranter, Robert (committee member), Violi, Angela (committee member).

Subjects/Keywords: combustion chemistry; siloxanes; reaction kinetics; biogas; rapid compression facility; shocktube; Mechanical Engineering; Engineering

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APA (6^th Edition):

Schwind, R. (2019). Understanding the Combustion Chemistry of Siloxanes: Reaction Kinetics and Fuel Interactions. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/153412

Chicago Manual of Style (16^th Edition):

Schwind, Rachel. “Understanding the Combustion Chemistry of Siloxanes: Reaction Kinetics and Fuel Interactions.” 2019. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/153412.

MLA Handbook (7^th Edition):

Schwind, Rachel. “Understanding the Combustion Chemistry of Siloxanes: Reaction Kinetics and Fuel Interactions.” 2019. Web. 10 Apr 2021.

Vancouver:

Schwind R. Understanding the Combustion Chemistry of Siloxanes: Reaction Kinetics and Fuel Interactions. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/153412.

Council of Science Editors:

Schwind R. Understanding the Combustion Chemistry of Siloxanes: Reaction Kinetics and Fuel Interactions. [Doctoral Dissertation]. University of Michigan; 2019. Available from: http://hdl.handle.net/2027.42/153412

University of Michigan

9. Lin, Kuang Chuan. Numerical Simulations of Thermal Systems-Applications To Fuel Chemistry, Nanofluid Heat Transfer And Aerosol Particle Transport.

Degree: PhD, Mechanical Engineering, 2011, University of Michigan

URL: http://hdl.handle.net/2027.42/86287

► In this dissertation, three topics in thermal systems are investigated: 1) the effect of methyl-ester content on combustion chemistry of a biodiesel surrogate; 2) the… (more)

▼ In this dissertation, three topics in thermal systems are investigated: 1) the effect of methyl-ester content on combustion chemistry of a biodiesel surrogate; 2) the effects of non-uniform particle sizes and fluid temperature on heat transfer characteristics of liquid water containing alumina nano-particles; 3) the effects of obstacle arrangements on transport of aerosol particles in channel flows. The investigation focuses on computational modeling and analysis in the above problems. In the first study, a kinetic modeling comparison of methyl butanoate and n-butane, its corresponding alkane, contrasts the combustion of methyl esters and normal alkanes, with the aim of understanding the effect of the methyl ester moiety. A fuel-breakdown model [J. Org. Chem. 2008, 73, 94; J. Phys. Chem. A 2008, 112, 51] is added to existing chemical kinetic mechanisms to improve the prediction of CO2 formation from MB decomposition. Sensitivity and reaction pathway analysis show that the absence of negative temperature coefficient behaviors and reduction of soot precursors can be ascribed to the effect of the methyl ester. The second study analyzes the heat transfer and fluid flow of natural convection in a cavity filled with Al2O3/water nanofluid that operates within differentially heated walls. The Navier-Stokes and energy equations are solved numerically, coupling the model of effective thermal conductivity [J. Phys. D 2006, 39, 4486] and model of effective dynamic viscosity [Appl. Phys. Lett. 2007, 91, 243112]. The numerical simulations explore the range where the heat transfer uncertainties can be affected by the operating conditions of the nanoparticles. Furthermore, the suppressed heat transfer phenomena are in good agreement with the latest experimental data of Ho et al. [Int. J. Therm. Sci. 2010, 49, 1345]. Finally, by using a simple lattice Boltzmann model coupled with a Lagrangian formalism, this study investigates the dispersion and deposition of aerosol particles over staggered obstacles in a two-dimensional channel flow. Particle motion mechanisms considered in the particle phase equation include drag, gravity, lift and Brownian forces. In this study, the results highlight the range of particle dimensions where the particle deposition can be affected by the arrangement of blocks placed in the channel flow. Advisors/Committee Members: Violi, Angela (committee member), Atreya, Arvind (committee member), Barker, John R. (committee member), Im, Hong G. (committee member).

Subjects/Keywords: Biodiesel; Chemical Kinetic Modeling; Nanofluids; Computational Fluid Dynamics; Aerosol Particles; Lattice Boltzmann; Mechanical Engineering; Engineering

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APA (6^th Edition):

Lin, K. C. (2011). Numerical Simulations of Thermal Systems-Applications To Fuel Chemistry, Nanofluid Heat Transfer And Aerosol Particle Transport. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/86287

Chicago Manual of Style (16^th Edition):

Lin, Kuang Chuan. “Numerical Simulations of Thermal Systems-Applications To Fuel Chemistry, Nanofluid Heat Transfer And Aerosol Particle Transport.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/86287.

MLA Handbook (7^th Edition):

Lin, Kuang Chuan. “Numerical Simulations of Thermal Systems-Applications To Fuel Chemistry, Nanofluid Heat Transfer And Aerosol Particle Transport.” 2011. Web. 10 Apr 2021.

Vancouver:

Lin KC. Numerical Simulations of Thermal Systems-Applications To Fuel Chemistry, Nanofluid Heat Transfer And Aerosol Particle Transport. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/86287.

Council of Science Editors:

Lin KC. Numerical Simulations of Thermal Systems-Applications To Fuel Chemistry, Nanofluid Heat Transfer And Aerosol Particle Transport. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/86287

University of Michigan

10. Teini, Paul Domenic. Soot Formation, Composition, and Morphology.

Degree: PhD, Mechanical Engineering, 2011, University of Michigan

URL: http://hdl.handle.net/2027.42/86420

► A complete understanding of soot particle formation is critical for accurate combustion models. Limited details are known about the polycyclic aromatic hydrocarbon (PAH) molecules that… (more)

▼ A complete understanding of soot particle formation is critical for accurate combustion models. Limited details are known about the polycyclic aromatic hydrocarbon (PAH) molecules that comprise soot mass, the physical processes involved in nascent soot formation, particle morphology transformation in high temperature environments, and the influence of products of combustion in the soot formation zone. These phenomena have been studied using a variety of fuels in the University of Michigan Rapid Compression Facility at high temperature (1600-2000 K) and high-pressure (10 atm) environments that are similar to those found in advanced combustion strategies. Details of soot particle nanostructure were identified using a high-resolution transmission electron microscope (HRTEM). This study discovered PAH molecule size distributions and particle morphologies from HRTEM images of nascent and mature soot particles. Molecules deposited on both nascent and aged soot particles had a constant size distribution. At low temperatures, amorphous nascent particles were created. At high temperatures, the nascent particles became comprised of agglomerated 2-8 nm diameter particles. Shortly after inception, the small particles no longer attached as growth species. A coagulation model replicated the experimental finding and relates small particle agglomeration to the PAH molecules rate of production. Particle morphologies were found to change as nascent particles mature. Transformations were also induced in HRTEM by irradiating nascent particles. Following irradiation, particle morphologies were very similar to mature particle morphologies created at high temperatures. HRTEM images of the transformation showed tangential molecular alignment at the particle surface, merging of adjacent particles, and epitaxial alignment of interior molecules with the surface molecules. Finally, it was discovered that CO2 enhanced soot formation rate in an oxygen deficient reaction zone when combined with acetylene fuel but had an undetectable affect on methane fuel. Gas chromatography confirmed the CO2 reactivity. A chemical kinetics investigation discovered that OH radical production from CO2 caused the enhancement in soot formation rate. OH radicals were less important in the methane fuels due to more prevalent reactions with H and CH3 radicals and a longer reaction pathway between the fuel and the aromatic molecules. Advisors/Committee Members: Atreya, Arvind (committee member), Driscoll, James F. (committee member), Violi, Angela (committee member), Wooldridge, Margaret S. (committee member).

Subjects/Keywords: Nascent Soot; Mature Soot; Polycyclic Aromatic Hydrocarbon (PAH); Nucleation; Inception; High-resolution Transmission Electron Microscope (HRTEM); Mechanical Engineering; Engineering

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APA (6^th Edition):

Teini, P. D. (2011). Soot Formation, Composition, and Morphology. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/86420

Chicago Manual of Style (16^th Edition):

Teini, Paul Domenic. “Soot Formation, Composition, and Morphology.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/86420.

MLA Handbook (7^th Edition):

Teini, Paul Domenic. “Soot Formation, Composition, and Morphology.” 2011. Web. 10 Apr 2021.

Vancouver:

Teini PD. Soot Formation, Composition, and Morphology. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/86420.

Council of Science Editors:

Teini PD. Soot Formation, Composition, and Morphology. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/86420

University of Michigan

11. Sun, Chenxi. Nanostructure and Reactivity of Soot Produced from Partially Premixed Charge Compression Ignition (PCCI) Combustion and Post Injection.

Degree: PhD, Mechanical Engineering, 2017, University of Michigan

URL: http://hdl.handle.net/2027.42/140920

► Researchers have invested significant effort on optimizing the engine operation mode while cutting down the emissions due to increasingly strict emissions regulations. This study explores… (more)

▼ Researchers have invested significant effort on optimizing the engine operation mode while cutting down the emissions due to increasingly strict emissions regulations. This study explores Partially-Premixed Charge Compression Ignition (PCCI) combustion and post injection in a light duty multicylinder turbodiesel engine to reduce particulate matter (PM) and NOx emissions without sacrificing the engine performance. Three different fuels are tested in this PCCI combustion research: Ultra Low Sulfur Diesel (ULSD), diesel fuel produced via a low temperature Fischer-Tropsch process (LTFT) and a Renewable Diesel (RD). Late injection PCCI combustion can reduce NOx emissions by 76-78% and reduce soot emissions by 25-35%. High cetane number (CN), high ignition quality fuels LTFT and RD only increase CO emissions by 40-45% and THC emissions by 11-16% under late injection PCCI combustion compared to conventional combustion, while ULSD increases CO emissions by 78% and THC emissions by 24% under late injection PCCI combustion. The reaction rate constants of soot produced from late injection PCCI combustion are 1.2-2.2 times higher than soot from the conventional combustion conditions. The reaction rate constants of soot from LTFT and RD fuels are 47-66% lower than soot produced from ULSD. Soots produced from PCCI combustion have smaller graphene layers, higher surface oxygen concentration and higher portion of amorphous carbon. In addition, the primary particle and particle aggregate sizes are around 25nm and 400 nm for conventional combustion soot, while 10 nm and 150 nm for late injection PCCI combustion soot. Soots produced from LTFT and RD fuel under conventional combustion, show internal burning during oxidation. However, soots produced from late injection PCCI combustion and ULSD show shrinking core oxidation, likely because of their overall amorphous structure. Post injection is another method to reduce engine-out soot emissions while maintaining efficiency, potentially to reduce or eliminate exhaust aftertreatment. Close-coupled post injections reduce soot emissions by 11-21%, THC emissions by 14-28%, and CO emissions by 7-8%. However, NOx emissions increase by 3-5%. For long-dwell post injection condition, soot emissions are reduced by 28-33% and NOx emissions are reduced by 7-8%. CO and THC emissions do not vary much under long dwell post injection conditions. The reaction rate constants of soot from close-coupled post injection conditions increase by 10-13% compared to baseline condition, while the reaction rate constants of soot from long dwell post injection conditions decrease by 37-39% compared to baseline condition. Moreover, with the increase of injection dwell and post injection size, soot surface oxygen content and amorphous carbon content increase. This explains the change in reactivity of soot from different injection dwells. Primary soot particle and particle aggregate sizes do not vary much with post injection. Soot from post injection conditions all show shrinking core type oxidation without graphene… Advisors/Committee Members: Boehman, Andre L (committee member), Lastoskie, Christian M (committee member), Violi, Angela (committee member), Wooldridge, Margaret S (committee member).

Subjects/Keywords: advanced combustion; soot reactivity; PCCI combustion; post injection; soot nanostructure; renewable diesel; Mechanical Engineering; Engineering

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APA (6^th Edition):

Sun, C. (2017). Nanostructure and Reactivity of Soot Produced from Partially Premixed Charge Compression Ignition (PCCI) Combustion and Post Injection. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/140920

Chicago Manual of Style (16^th Edition):

Sun, Chenxi. “Nanostructure and Reactivity of Soot Produced from Partially Premixed Charge Compression Ignition (PCCI) Combustion and Post Injection.” 2017. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/140920.

MLA Handbook (7^th Edition):

Sun, Chenxi. “Nanostructure and Reactivity of Soot Produced from Partially Premixed Charge Compression Ignition (PCCI) Combustion and Post Injection.” 2017. Web. 10 Apr 2021.

Vancouver:

Sun C. Nanostructure and Reactivity of Soot Produced from Partially Premixed Charge Compression Ignition (PCCI) Combustion and Post Injection. [Internet] [Doctoral dissertation]. University of Michigan; 2017. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/140920.

Council of Science Editors:

Sun C. Nanostructure and Reactivity of Soot Produced from Partially Premixed Charge Compression Ignition (PCCI) Combustion and Post Injection. [Doctoral Dissertation]. University of Michigan; 2017. Available from: http://hdl.handle.net/2027.42/140920

University of Michigan

12. Liu, Changjiang. The Permeation Behavior of Nanoparticles in Lipid Membranes.

Degree: PhD, Biophysics, 2020, University of Michigan

URL: http://hdl.handle.net/2027.42/163056

► The number of engineered nanoparticles for applications in the biomedical arena has grown tremendously over the last years due to advances in the science of… (more)

▼ The number of engineered nanoparticles for applications in the biomedical arena has grown tremendously over the last years due to advances in the science of synthesis and characterization. For most applications, the crucial step is the transport through a physiological cellular membrane. However, the behavior of nanoparticles in a biological matrix is a very complex problem that depends not only on the type of nanoparticle, but also on its size, shape, phase, surface charge, chemical composition and agglomeration state. In this thesis, I introduce a streamlined theoretical model that predicts the average time of entry of nanoparticles in lipid membranes, using a combination of molecular dynamics simulations and statistical approaches. The uniqueness of the model lies in the ability to identify four parameters that separate the contributions of nanoparticle characteristics (i.e. size, shape, solubility) from the membrane properties (density distribution and dynamics). This factorization allows the inclusion of data obtained from both experimental and computational sources, as well as a rapid estimation of large sets of permutations in membranes. The robustness of the model is supported by experiments carried out in lipid vesicles encapsulating graphene quantum dots as nanoparticles. The model is applied to the study of various nanoparticles, biological membranes (i.e. mammalian cellular organelles, viral envelopes), and environmental conditions. Overall, this work contributes to the understanding and prediction of interactions between nanoparticles and lipid membranes, responding to the high level of interest across multiple areas of study in modulating intracellular targets, and the need to understand and improve the applications of nanoparticles and to assess their effect on human health (i.e. cytotoxicity, bioavailability). Advisors/Committee Members: Elvati, Paolo (committee member), Violi, Angela (committee member), VanEpps, Jeremy Scott (committee member), Veatch, Sarah (committee member), Wood, Kevin (committee member).

Subjects/Keywords: lipid bilayer; molecular dynamics simulation; permeability; nanoparticle; graphene quantum dot; Physics; Science

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APA (6^th Edition):

Liu, C. (2020). The Permeation Behavior of Nanoparticles in Lipid Membranes. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/163056

Chicago Manual of Style (16^th Edition):

Liu, Changjiang. “The Permeation Behavior of Nanoparticles in Lipid Membranes.” 2020. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/163056.

MLA Handbook (7^th Edition):

Liu, Changjiang. “The Permeation Behavior of Nanoparticles in Lipid Membranes.” 2020. Web. 10 Apr 2021.

Vancouver:

Liu C. The Permeation Behavior of Nanoparticles in Lipid Membranes. [Internet] [Doctoral dissertation]. University of Michigan; 2020. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/163056.

Council of Science Editors:

Liu C. The Permeation Behavior of Nanoparticles in Lipid Membranes. [Doctoral Dissertation]. University of Michigan; 2020. Available from: http://hdl.handle.net/2027.42/163056

University of Michigan

13. Easter, Jordan. Influence of Fuel Introduction Parameters on the Reactivity and Oxidation Process of Soot from a Gasoline Direct Injection Engine.

Degree: PhD, Mechanical Engineering, 2018, University of Michigan

URL: http://hdl.handle.net/2027.42/143938

► Upcoming regulations, such as Euro 6c, decrease limits on allowable tailpipe particulate number emissions. These regulations may place some current gasoline engine technologies above the… (more)

▼ Upcoming regulations, such as Euro 6c, decrease limits on allowable tailpipe particulate number emissions. These regulations may place some current gasoline engine technologies above the legal limit, especially those vehicles using direct fuel injection. Therefore, gasoline particulate filters (GPF) may be necessary for future emissions compliance. The key functionality of the GPF is filtration efficiency and control of this function is dependent on the soot build-up within the filter. The more soot present, the higher the filtration efficiency. As soot will often oxidize during much of the engine operation due to high temperatures and available oxygen, an understanding of soot reactivity and the degree to which reactivity may vary is key for designing after-treatment architecture and explaining low filtration efficiency results in real world situations. In this work, soot was evaluated from four conditions incorporating changes in the fuel injection pressure and timing, and the influence these parameter variations had on soot reactivity was evaluated through well-controlled isothermal and ramped oxidation events. It was determined that soot reactivity and the temperature by which oxidation would commence were quite different for the four samples. Following this, soot parameters known to influence reactivity were investigated. It was determined that nanostructure, volatile organic fraction and surface functional groups were similar between all four samples and though surface area was different, it did not correlate with reactivity. It was determined through estimations of the ash content that soot reactivity was likely influenced by the ash too soot ratio of the particulate matter. Ash is a known catalyst, found to enhance soot oxidation rates. The presence of ash and the interaction of soot and ash were investigated using a scanning transmission electron microscope coupled with energy dispersive x-ray spectroscopy (STEM+EDS). To carry further the investigation, soot samples from the most and least reactive condition underwent partial oxidation and the partially oxidized soots were analyzed to obtain information regarding the oxidation process. During oxidation, the soot particles appeared more amorphous and began to meld into each other, forming larger non-spherical particles. It was determined that beyond a sufficient ash-soot ratio, a ratio likely below 1% and easily reached for a modern gasoline direct injection engine, the soot oxidation process is marked by three distinct phases relating to interactions of ash and soot particles. In the first phase, the oxidation rate is enhanced by the presence of close soot to ash contact. Soot in close contact with the ash will oxidize first, leaving a loose contact between the ash and soot. This loose contact causes the observed distinction in the second stage. In the second stage, despite increases in the ash to soot ratio due to the loss of soot, the oxidation rate decreases due to the loose ash to soot contact. As oxidation proceeds, soot particles begin to meld… Advisors/Committee Members: Boehman, Andre L (committee member), Bohac, Stani V (committee member), Violi, Angela (committee member), Clack, Herek (committee member), Daley, James (committee member), Hoard, John W (committee member).

Subjects/Keywords: Reactivity of Gasoline Soot from Differing Fuel Introduction Parameters; Mechanical Engineering; Engineering

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APA (6^th Edition):

Easter, J. (2018). Influence of Fuel Introduction Parameters on the Reactivity and Oxidation Process of Soot from a Gasoline Direct Injection Engine. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/143938

Chicago Manual of Style (16^th Edition):

Easter, Jordan. “Influence of Fuel Introduction Parameters on the Reactivity and Oxidation Process of Soot from a Gasoline Direct Injection Engine.” 2018. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/143938.

MLA Handbook (7^th Edition):

Easter, Jordan. “Influence of Fuel Introduction Parameters on the Reactivity and Oxidation Process of Soot from a Gasoline Direct Injection Engine.” 2018. Web. 10 Apr 2021.

Vancouver:

Easter J. Influence of Fuel Introduction Parameters on the Reactivity and Oxidation Process of Soot from a Gasoline Direct Injection Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/143938.

Council of Science Editors:

Easter J. Influence of Fuel Introduction Parameters on the Reactivity and Oxidation Process of Soot from a Gasoline Direct Injection Engine. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/143938

14. Choi, Jeongyong. Recycled Water Injection in a Turbocharged Gasoline Engine and Detailed Effects of Water on Auto-Ignition.

Degree: PhD, Mechanical Engineering, 2019, University of Michigan

URL: http://hdl.handle.net/2027.42/149814

► In recent years, many engine manufacturers have turned to downsizing and boosting of gasoline engines in order to meet the ever more stringent fuel economy… (more)

▼ In recent years, many engine manufacturers have turned to downsizing and boosting of gasoline engines in order to meet the ever more stringent fuel economy and emissions regulations. With an increase in the number of turbocharged gasoline engines, solutions are required to manage knock under a range of operating conditions. The engine is required to operate with spark retard and/or boost reduction to provide knock reduction leading to reduced fuel economy. The charge air cooler has been introduced to mitigate knock and yield a denser intake charge. However, under certain conditions, water condenses onto the charge air cooler inner surfaces, and this water can be introduced into the combustion chamber. Therefore, water ingestion may cause abnormal combustion. In addition, many researchers have advocated water injection as an approach to replace or supplement existing knock mitigation techniques. To maximize the efficiency of the water injection system for a given amount of water, a deeper understanding of the ability to capture and utilize water is required. The first part of this dissertation pursues an understanding of the condensates generated inside of the charge air cooler is discussed. To understand the ingestion of condensates into the cylinders, the hard acceleration is applied with the condensates and quantitatively correlated the amount of condensation and number of abnormal combustion behavior such as misfire and slowburn in different engine conditions. The next study is designing the condensation separator to prevent the abnormal combustion behavior due to the condensates ingestion. An approach to designing a unit to separate condensation in the flow from the charge air cooler while maintaining a low pressure drop is described. The effect of water on auto-ignition is described using modified CFR engine. Three test fuels gasoline, PRF, and TRF which have similar RON blends are used for this test at various intake pressure and amount of water conditions. The first test is done with constant intake air temperature and φ to exclude the effects of intake air cooling. For the second part of this research, the comparison of the effect of the intake air cooling and the effect of the intake air property change is made. The numerical calculations of the chemical effect of water addition with high octane number fuels and oxygenated fuels such as iso-Octane, toluene, n-Butanol, and Ethanol are presented. Using chemical reaction simulation, CHEMKIN, the simulations have been conducted on the change of hydrocarbon and oxygenated hydrocarbon oxidations process with water addition by examining ignition delay, sensitivity analysis and chemical reaction pathway analysis. At the beginning of the study, change of the ignition delay due to water addition is quantified. Then, the sensitivity analysis and the reaction pathway analysis are carried out to verify more detail of chemical effect of water on combustion process. Through the studies presented in this thesis, some of potential contributions to high efficiency… Advisors/Committee Members: Boehman, Andre L (committee member), Hoard, John W (committee member), Raman, Venkatramanan (committee member), Violi, Angela (committee member).

Subjects/Keywords: Charge air cooler condensate; Water injection; Mechanical Engineering; Engineering

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APA (6^th Edition):

Choi, J. (2019). Recycled Water Injection in a Turbocharged Gasoline Engine and Detailed Effects of Water on Auto-Ignition. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/149814

Chicago Manual of Style (16^th Edition):

Choi, Jeongyong. “Recycled Water Injection in a Turbocharged Gasoline Engine and Detailed Effects of Water on Auto-Ignition.” 2019. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/149814.

MLA Handbook (7^th Edition):

Choi, Jeongyong. “Recycled Water Injection in a Turbocharged Gasoline Engine and Detailed Effects of Water on Auto-Ignition.” 2019. Web. 10 Apr 2021.

Vancouver:

Choi J. Recycled Water Injection in a Turbocharged Gasoline Engine and Detailed Effects of Water on Auto-Ignition. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/149814.

Council of Science Editors:

Choi J. Recycled Water Injection in a Turbocharged Gasoline Engine and Detailed Effects of Water on Auto-Ignition. [Doctoral Dissertation]. University of Michigan; 2019. Available from: http://hdl.handle.net/2027.42/149814

15. Yau, Sung-Hei. Understanding Metal Nonoclusters through Ultrafast and Nonlinear Spectroscopy.

Degree: PhD, Chemistry, 2013, University of Michigan

URL: http://hdl.handle.net/2027.42/99761

► In the past 20 years, nanomaterials studies have uncovered many new and interesting properties not found in bulk materials. Extensive research has focused on metal… (more)

▼ In the past 20 years, nanomaterials studies have uncovered many new and interesting properties not found in bulk materials. Extensive research has focused on metal nanoparticles (> 2 nm) because of their potential applications, such as molecular electronics, image markers and catalysts. Moreover, the discovery of metal nanoclusters (< 2 nm) has greatly expanded the horizon of nanomaterial research. These nanosystems exhibit molecular-like characteristics as their size approaches the Fermi-wavelength of an electron. The relationships between size and physical properties of nanomaterials are intriguing. Metal nanosystems in this size regime have electronic properties that are determined by both size and shape. Remarkably, changes in the optical properties of nanomaterials have provided tremendous insight into the electronic structure of nanoclusters. The success of synthesizing monolayer protected clusters (MPCs) in the condensed phase has allowed scientists to study the metal core directly. Spectroscopic studies are carried out on two different metal nanosystems, gold and silver. Gold nanosystems are known for their high stability. Detailed characterization of gold nanosystems allows for modeling of the electronic and optical properties. Major optical and electronic differences between gold nanoparticles and nanoclusters can be observed around 2.2 nm, which was not known previously. Gold MPCs also exhibit emissions that are five orders of magnitude larger than bulk gold. Chemical dynamics such as electron-electron scattering and electron-phonon coupling can be used to explain the subtle differences between nanosystems. Silver and gold nanosystems are compared because of the similarity between their bulk properties. Silver MPCs exhibit similar optical properties as gold MPCs, but differ in key electronic transitions. The study of nanosystems aims to answer a few major questions. First, what is the effect of size on the electronic and optical properties of metal nanosystems? Second, what are the fundamental mechanisms that govern the electronic excitation? Can we take advantage of these new properties for optical and electronic applications? Finally, can we build better models to predict the properties of metal nanoclusters made and yet to be made? Nanosystem presents a new frontier in material science to be explored and exploited. Advisors/Committee Members: Goodson, Theodore G. (committee member), Geva, Eitan (committee member), Violi, Angela (committee member), Kopelman, Raoul (committee member).

Subjects/Keywords: Ultrafast Optical Study of Nanoclusters; Chemistry; Science

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APA (6^th Edition):

Yau, S. (2013). Understanding Metal Nonoclusters through Ultrafast and Nonlinear Spectroscopy. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/99761

Chicago Manual of Style (16^th Edition):

Yau, Sung-Hei. “Understanding Metal Nonoclusters through Ultrafast and Nonlinear Spectroscopy.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/99761.

MLA Handbook (7^th Edition):

Yau, Sung-Hei. “Understanding Metal Nonoclusters through Ultrafast and Nonlinear Spectroscopy.” 2013. Web. 10 Apr 2021.

Vancouver:

Yau S. Understanding Metal Nonoclusters through Ultrafast and Nonlinear Spectroscopy. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/99761.

Council of Science Editors:

Yau S. Understanding Metal Nonoclusters through Ultrafast and Nonlinear Spectroscopy. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/99761

16. Arias, Paul G. High-Fidelity Simulations to Study Spray-Induced Extinction and Particulate Formation Characteristics of Nonpremixed Ethylene-Air Flames.

Degree: PhD, Mechanical Engineering, 2013, University of Michigan

URL: http://hdl.handle.net/2027.42/97857

► This work developed and employed high-fidelity direct numerical simulations to investigate fundamental flame behavior in laminar and turbulence nonpremixed flames. The scope of the work… (more)

▼ This work developed and employed high-fidelity direct numerical simulations to investigate fundamental flame behavior in laminar and turbulence nonpremixed flames. The scope of the work includes several advances in computational algorithms such as improved Navier-Stokes Characteristic Boundary Conditions (NSCBC) for mass additive systems and advanced soot models. In addition, detailed investigations into the effects of thermal quenching were conducted in an effort to understand ways of accurately describing the nature of flame extinction comprehensively. As an application to fundamental and practical combustion problems, the study investigates the interaction of water spray and turbulence with nonpremixed diffusion flames. The simulations incorporate detailed chemistry of ethylene flames, the chemistry of which is recognized as an important chemical pathway for combustion processes. A unified extinction condition that accounts for thermal quenching and strain induced quenching simultaneously is demonstrated to be effective at capturing the moment of extinction and tracking extinction holes in turbulent flames. The findings show that in the formation of edge flames, the evolution leading to the flame recovery or total extinction is found to depend strongly on the temporal history of the local strain rate as well as the presence of the spray droplets. While turbulent mixing leads to the formation of the edge flames, the presence of spray droplets suppresses the ability of edge flames to heal extinction holes. The final part of this study examines the dynamics of soot formation in ethylene-air nonpremixed flames using a Method of Moments with Interpolative Closure (MOMIC) approach. A number of technical challenges related to the simulation of soot and gas phases were addressed. The treatment of the interpolation moments, which play a role in the diffusion of soot as well as the soot reaction source terms, was found to be consistent with the mathematic description of MOMIC, and was shown to be consistent with the conditions of statistical realizability of the soot moments for the reaction test cases. The results of this study provide the Direct Numerical Simulation (DNS) community with a numerical framework towards the development and implementation of high-fidelity soot sub-models. Advisors/Committee Members: Im, Hong G. (committee member), Ihme, Matthias (committee member), Atreya, Arvind (committee member), Violi, Angela (committee member).

Subjects/Keywords: Direct Numerical Simulation; Navier-Stokes Characteristics Boundary Conditions; Method of Moments With Interpolative Closure; Mechanical Engineering; Engineering

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APA (6^th Edition):

Arias, P. G. (2013). High-Fidelity Simulations to Study Spray-Induced Extinction and Particulate Formation Characteristics of Nonpremixed Ethylene-Air Flames. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/97857

Chicago Manual of Style (16^th Edition):

Arias, Paul G. “High-Fidelity Simulations to Study Spray-Induced Extinction and Particulate Formation Characteristics of Nonpremixed Ethylene-Air Flames.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/97857.

MLA Handbook (7^th Edition):

Arias, Paul G. “High-Fidelity Simulations to Study Spray-Induced Extinction and Particulate Formation Characteristics of Nonpremixed Ethylene-Air Flames.” 2013. Web. 10 Apr 2021.

Vancouver:

Arias PG. High-Fidelity Simulations to Study Spray-Induced Extinction and Particulate Formation Characteristics of Nonpremixed Ethylene-Air Flames. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/97857.

Council of Science Editors:

Arias PG. High-Fidelity Simulations to Study Spray-Induced Extinction and Particulate Formation Characteristics of Nonpremixed Ethylene-Air Flames. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/97857

17. Sobczynski, Daniel J. The Impact of the Plasma Protein Corona on the Adhesion Efficiency of Drug Carriers to the Blood Vessel Wall.

Degree: PhD, Chemical Engineering, 2016, University of Michigan

URL: http://hdl.handle.net/2027.42/133204

► Upon injection of vascular-targeted drug carriers into the bloodstream, plasma proteins rapidly coat the carrier surface, forming a plasma protein corona. This corona is dependent… (more)

▼ Upon injection of vascular-targeted drug carriers into the bloodstream, plasma proteins rapidly coat the carrier surface, forming a plasma protein corona. This corona is dependent on a host of parameters, including physicochemical particle properties and the plasma composition. Although several studies have identified key roles of the protein corona regarding circulation time, clearance, and biodistribution, the role of the plasma protein corona on the adhesion efficiency of vascular-targeted carriers (VTCs) to inflamed human umbilical vein endothelial cells (HUVECs) in human blood flow remains relatively unknown. In this dissertation, it is observed that the plasma protein corona exerts a negative effect on the adhesion of drug carriers in blood flow; however, the extent of these observations depend on a host of parameters including drug carrier material type, targeting ligand density, flow profile, plasma exposure time, and plasma anticoagulant. Furthermore, the magnitude of the corona-induced negative adhesion effects is shown to be heavily linked to the adsorption of immunoglobulin antibodies in plasma. This work has a variety of important implications for the intelligent design of VTCs. First, the fact that immunoglobulins heavily dictate adhesion reduction of drug carriers offers insight into specific directions to limit the effects of the protein corona. Specifically, tuning the corona to avoid adsorption of these proteins or coating with non-fouling dysopsonin proteins offers a method to maintain targeting efficiency in the presence of corona formation. Second, this work may explain why current targeted drug delivery systems often exhibit poor accumulation to the target site based on the large reduction of particles upon exposure to human plasma. Third, this work could be used to develop strategies to predict or diagnose a specific drug carrier based on its protein corona profile, hopefully leading to more successful translations of drug delivery systems to the market. Overall, this work shows that protein corona is a critical parameter when designing high-efficient targeted drug carriers and may be exploited or eliminated to achieve maximum adhesion specificity in vivo. Advisors/Committee Members: Eniola-Adefeso, Lola (committee member), Violi, Angela (committee member), Linderman, Jennifer J (committee member), Thurber, Greg Michael (committee member).

Subjects/Keywords: Plasma protein corona; Vascular-targeted drug delivery; Blood flow adhesion efficiency; Biomedical Engineering; Chemical Engineering; Engineering; Science

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APA (6^th Edition):

Sobczynski, D. J. (2016). The Impact of the Plasma Protein Corona on the Adhesion Efficiency of Drug Carriers to the Blood Vessel Wall. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/133204

Chicago Manual of Style (16^th Edition):

Sobczynski, Daniel J. “The Impact of the Plasma Protein Corona on the Adhesion Efficiency of Drug Carriers to the Blood Vessel Wall.” 2016. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/133204.

MLA Handbook (7^th Edition):

Sobczynski, Daniel J. “The Impact of the Plasma Protein Corona on the Adhesion Efficiency of Drug Carriers to the Blood Vessel Wall.” 2016. Web. 10 Apr 2021.

Vancouver:

Sobczynski DJ. The Impact of the Plasma Protein Corona on the Adhesion Efficiency of Drug Carriers to the Blood Vessel Wall. [Internet] [Doctoral dissertation]. University of Michigan; 2016. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/133204.

Council of Science Editors:

Sobczynski DJ. The Impact of the Plasma Protein Corona on the Adhesion Efficiency of Drug Carriers to the Blood Vessel Wall. [Doctoral Dissertation]. University of Michigan; 2016. Available from: http://hdl.handle.net/2027.42/133204

18. Park, Jungkap. Rotamer-specific Statistical Potentials for Protein Structure Modeling.

Degree: PhD, Mechanical Engineering, 2013, University of Michigan

URL: http://hdl.handle.net/2027.42/102342

► Knowledge-based (or statistical) potentials are widely used as essential tools in protein structure modeling and quality assessment. They are derived from experimentally determined protein structures… (more)

▼ Knowledge-based (or statistical) potentials are widely used as essential tools in protein structure modeling and quality assessment. They are derived from experimentally determined protein structures aiming to extract relevant structural features that characterize the tightly folded structures. Since the surrounding circumstances are inhomogeneous and anisotropic, multibody contributions are important for accurate account of cooperative effects of molecular interactions. On the other hand, protein residues have great flexibility. It is energetically favorable for residues to adopt only a limited number of staggered conformations, known as rotamers. Depending on the rotameric state, the residue conformation and intra-residue interaction vary significantly within protein structures, resulting in different solvent accessibility and different electric polarization effect as well as different steric effect on residue elements. The major goal of this thesis is the design and development of statistical potentials that take into account the rotamer-dependence of interactions. We hypothesized that the rotameric state of residues is related to the specificity of interactions within protein structures. We first investigated how amino acid residues in PDB structures show different interaction patterns with the environment depending on their rotameric states. Observed rotamer-specific environmental features were incorporated to a scoring function, ProtGrid for protein designs. Our tests demonstrated that the ProtGrid is superior to widely used Rosetta energy function in prediction of the native amino acid types and rotameric states. Next, we formulated a rotamer-specific atomic statistical potential, named ROTAS that extends an existing orientation-dependent atomic potential (GOAP) by including the influence of rotameric states of residues on the specificity of interactions. The results showed that ROTAS performs better than other competing potentials not only in native structure recognition, but also in best model selection and correlation coefficients between energy and model quality. Finally, we applied the ROTAS potential to the problem of side-chain prediction. Compared with the existing side-chain modeling programs, ROTAS achieved comparable or even better prediction accuracy. We expect that the effectiveness of our energy functions would provide insightful information for the development of many applications which require accurate side-chain modeling such as homology modeling, protein design, mutation analysis, protein-protein docking and flexible ligand docking. Advisors/Committee Members: Saitou, Kazuhiro (committee member), Zhang, Yang (committee member), Young, Matthew A. (committee member), Violi, Angela (committee member).

Subjects/Keywords: Protein Structure Prediction; Statistical Potential Energy Function; Rotamer-specific Multibody Potential; Mechanical Engineering; Engineering

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APA (6^th Edition):

Park, J. (2013). Rotamer-specific Statistical Potentials for Protein Structure Modeling. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/102342

Chicago Manual of Style (16^th Edition):

Park, Jungkap. “Rotamer-specific Statistical Potentials for Protein Structure Modeling.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/102342.

MLA Handbook (7^th Edition):

Park, Jungkap. “Rotamer-specific Statistical Potentials for Protein Structure Modeling.” 2013. Web. 10 Apr 2021.

Vancouver:

Park J. Rotamer-specific Statistical Potentials for Protein Structure Modeling. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/102342.

Council of Science Editors:

Park J. Rotamer-specific Statistical Potentials for Protein Structure Modeling. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/102342

19. Huang, Wenjun. Multi-Scale Modeling of Cellulosic Polymers for Optimal Drug Delivery Properties in Solid Dispersion Formulation.

Degree: PhD, Chemical Engineering, 2017, University of Michigan

URL: http://hdl.handle.net/2027.42/138745

► Solid dispersion formulation is a promising method to maintain in vivo drug solubility and to improve drug efficacy. However, the exact drug stabilization and release… (more)

▼ Solid dispersion formulation is a promising method to maintain in vivo drug solubility and to improve drug efficacy. However, the exact drug stabilization and release mechanisms of the solid dispersion formulation are unclear. In this doctoral work, we present a multi-scale modeling approach to study the solvation behavior of cellulosic polymers and their interactions with the model drug phenytoin. We compare a number of atomistic force fields and find they give similar predictions for the stiffness of the cellulose chains. We then develop systematic coarse-grained (CG) force fields for two cellulosic polymers, namely methylcellulose and hydroxylpropyl methylcellulose acetate succinate (HPMCAS), based on the radial distribution functions obtained from atomistic simulations. We use the methylcellulose CG model to simulate the self-assembly of multiple 1000 monomers long polymer chains, and find that they spontaneously form ring or tubular structures with outer diameter of 14nm and void fraction of 26%. These structures appear to be precursors to the methylcellulose fibrils, whose diameter and structure are in good agreement with both theoretical and experimental results, and thus shine light on the methylcellulose gelation mechanism. We also present a simplified continuum analytical model to predict a phase map of the collapse conformations of a single self-attractive semiflexible polymer chain in solution into either folded or ring structures depending on the chains bending energy and self-interaction energy. The predicted phase map is in good qualitative agreement with simulation results for these collapsed structures. We use the HPACAS CG model to study the intermolecular interaction modes between 9 functional groups on HPMCAS and model drug phenytoin. We adopt two criteria to quantify the effectiveness of the polymeric excipients, namely 1) the ability to inhibit drug aggregation and 2) the ability to slow down drug release. We find the size of the functional group is more responsible for the former, while the intermolecular interaction strength is more responsible for the later. Therefore, hydroxypropyl acetyl group, which has both bulky size and strong interaction strength, is the most effective functional group, followed by hydroxypropyl and acetyl group, in good agreement with the results from experimental dissolution tests. In addition, we provide continuum models and predict that the drug release time from a typical solid dispersion particle with 2μm diameter ranges from several seconds to less than 10 minutes depending on the functional group. The systematic coarse-graining approach offer molecular level insights that aid the design of high performance polymeric excipients, and can be extended to cellulosic polymers with novel functional groups and additional drug candidates of interest. Thus, our multi-scale modeling approach is of great interest to the pharmaceutical and material design fields. Advisors/Committee Members: Larson, Ronald G (committee member), Violi, Angela (committee member), Glotzer, Sharon C (committee member), Wen, Fei (committee member).

Subjects/Keywords: Coarse-Grained; Self-Assembly; Gelation; Dissolution; Continuum Modeling; Atomistic Simulation; Chemical Engineering; Engineering

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APA (6^th Edition):

Huang, W. (2017). Multi-Scale Modeling of Cellulosic Polymers for Optimal Drug Delivery Properties in Solid Dispersion Formulation. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/138745

Chicago Manual of Style (16^th Edition):

Huang, Wenjun. “Multi-Scale Modeling of Cellulosic Polymers for Optimal Drug Delivery Properties in Solid Dispersion Formulation.” 2017. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/138745.

MLA Handbook (7^th Edition):

Huang, Wenjun. “Multi-Scale Modeling of Cellulosic Polymers for Optimal Drug Delivery Properties in Solid Dispersion Formulation.” 2017. Web. 10 Apr 2021.

Vancouver:

Huang W. Multi-Scale Modeling of Cellulosic Polymers for Optimal Drug Delivery Properties in Solid Dispersion Formulation. [Internet] [Doctoral dissertation]. University of Michigan; 2017. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/138745.

Council of Science Editors:

Huang W. Multi-Scale Modeling of Cellulosic Polymers for Optimal Drug Delivery Properties in Solid Dispersion Formulation. [Doctoral Dissertation]. University of Michigan; 2017. Available from: http://hdl.handle.net/2027.42/138745

20. Dillstrom, Vernon. Predicting the Formation Pathways and Morphologies of Oxygenated Carbonaceous Nanoparticle Precursors in Premixed Flames.

Degree: PhD, Mechanical Engineering, 2017, University of Michigan

URL: http://hdl.handle.net/2027.42/138687

► Organic nanoparticles are an inevitable by-product of combustion phenomena that have deleterious health and environmental effects. They are carcinogenic because they damage biological cells due… (more)

▼ Organic nanoparticles are an inevitable by-product of combustion phenomena that have deleterious health and environmental effects. They are carcinogenic because they damage biological cells due to their small size and their presence in the atmosphere contributes to global warming. We would be better able to effectively manage the harmful effects of these nanoparticles if we better understood their formation mechanisms and chemical compositions at an atomic level. The complexities of the reaction chemistry involved along with the difficulties of experimental techniques to capture the atomic level details of nanoparticles and their chemical precursor molecules during flame synthesis, has led to a gap in the understanding of their formation pathways and molecular structures. This work presents a novel chemical kinetic reaction scheme and utilizes a computational approach to model laboratory-scale flames in order to elucidate the compositions and morphologies of organic nanoparticle precursors. Organic nanoparticles formed during combustion have long been assumed to comprise only hydrogen and carbon atoms, however, recent work has noted the presence of oxygen atoms. Using the first model to account for oxygenation of aromatic precursors, this work demonstrates that oxygen chemistry is key to understanding the formation pathways and morphologies of nanoparticles and their chemical precursors. Kinetic oxygenation pathways capture the influence of alcohol-doped-fuel on particle formation in premixed flames by identifying the fuel’s effect on precursor growth. Stochastic simulations reveal an abundance of previously unconsidered oxygenated aromatic species to be present in premixed aromatic- and aliphatic-fuel flames. Key morphologies of oxygenated precursor species predicted by the model were confirmed in experiments, including a significant presence of furanic compounds. Similarly, simulations led to experiments that confirmed model predictions that large oxygenated aromatic molecules are important participants in particle formation. The model developed in this work demonstrates for the first time that inclusion of oxygenation pathways is necessary and vital in order to represent the chemical kinetic growth of nanoparticle precursors in premixed flames. The recognition of the previously unexpected importance of oxygenated aromatic precursors and their influence on nanoparticle formation in flames constitutes a notable advancement in the field of combustion-generated nanoparticle chemistry. The impact of the present findings are considerable to the efforts to investigate combustion generated particle formation with the aim to reduce their deleterious health and environmental effects. Advisors/Committee Members: Violi, Angela (committee member), Fogler, Hugh Scott (committee member), Barker, John R (committee member), Wooldridge, Margaret S (committee member).

Subjects/Keywords: Polycyclic Aromatic Hydrocarbons; Soot; Combustion; Particulates; Modeling; Oxygenation; Chemical Engineering; Computer Science; Materials Science and Engineering; Mechanical Engineering; Chemistry; Science (General); Engineering; Science

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APA (6^th Edition):

Dillstrom, V. (2017). Predicting the Formation Pathways and Morphologies of Oxygenated Carbonaceous Nanoparticle Precursors in Premixed Flames. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/138687

Chicago Manual of Style (16^th Edition):

Dillstrom, Vernon. “Predicting the Formation Pathways and Morphologies of Oxygenated Carbonaceous Nanoparticle Precursors in Premixed Flames.” 2017. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/138687.

MLA Handbook (7^th Edition):

Dillstrom, Vernon. “Predicting the Formation Pathways and Morphologies of Oxygenated Carbonaceous Nanoparticle Precursors in Premixed Flames.” 2017. Web. 10 Apr 2021.

Vancouver:

Dillstrom V. Predicting the Formation Pathways and Morphologies of Oxygenated Carbonaceous Nanoparticle Precursors in Premixed Flames. [Internet] [Doctoral dissertation]. University of Michigan; 2017. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/138687.

Council of Science Editors:

Dillstrom V. Predicting the Formation Pathways and Morphologies of Oxygenated Carbonaceous Nanoparticle Precursors in Premixed Flames. [Doctoral Dissertation]. University of Michigan; 2017. Available from: http://hdl.handle.net/2027.42/138687

21. Chung, Seung-Hyun. Computational Modeling of Soot Nucleation.

Degree: PhD, Mechanical Engineering, 2011, University of Michigan

URL: http://hdl.handle.net/2027.42/86455

► Recent studies indicate that soot is the second most significant driver of climate change - behind CO2, but ahead of methane - and increased levels… (more)

Subjects/Keywords: Soot Nucleation; Mechanical Engineering; Engineering

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APA (6^th Edition):

Chung, S. (2011). Computational Modeling of Soot Nucleation. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/86455

Chicago Manual of Style (16^th Edition):

Chung, Seung-Hyun. “Computational Modeling of Soot Nucleation.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/86455.

MLA Handbook (7^th Edition):

Chung, Seung-Hyun. “Computational Modeling of Soot Nucleation.” 2011. Web. 10 Apr 2021.

Vancouver:

Chung S. Computational Modeling of Soot Nucleation. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/86455.

Council of Science Editors:

Chung S. Computational Modeling of Soot Nucleation. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/86455

22. Huston, Kyle. Linking the Continuum and Molecular Scales of Adsorption Modeling for Non-Ionic Small Molecules and Homopolymers.

Degree: PhD, Chemical Engineering, 2018, University of Michigan

URL: http://hdl.handle.net/2027.42/144112

► Computational tensiometry and other quantitative adsorption predictions for small molecules and polymers are possible in the foreseeable future, but first, the application of the techniques… (more)

▼ Computational tensiometry and other quantitative adsorption predictions for small molecules and polymers are possible in the foreseeable future, but first, the application of the techniques to surfactant adsorption must be developed, and basic research is needed to identify the set of minimally required features of the molecular model that permits quantitative prediction. We take up the first challenge and apply three methods to three adsorption problems. In the first approach, we simulate poly(ethylene oxide) (PEO) oligomers and a model Tween 80 (polyoxyethylene sorbitan monooleate) molecule at the water/alkane interface. We use the weighted histogram analysis method (WHAM) to calculate interfacial potentials of mean force (PMFs) for PEG and Tween 80 using the atomistic GROMOS 53a6OXY+D and two coarse-grained (CG) MARTINI force fields. Because the force fields have not yet been validated for PEO adsorption to hydrophobic interfaces, we calculate PMFs for alcohol ethoxylates C12E2 and C12E8 and find agreement for the atomistic forcefield with reported semiempirical results, whereas for both CG force fields, PEO adsorbs too weakly to the hydrophobic interface. With the newly validated atomistic force field, we bracket the dilute adsorption free energy for a model Tween 80 molecule at the clean water/squalane interface. We also calculate the pressure–area isotherm and—with molecular thermodynamic theory and a simple transport model—demonstrate the transition from irreversible to reversible adsorption with increasing surface coverage, consistent with past experimental reporting. In the second approach, we sought to explain experiments that show relaxation of oil/water interfacial tension by adsorption of alkyl ethoxylate surfactants from water is delayed relative to diffusion-controlled adsorption. We examine possible causes of this delay. We argue that a theory implicating transient depletion near an adsorbing interface for suppressing interfacial relaxation is invalid. We find that re-dissolution of the surfactant in the oil droplet cannot explain the apparent interfacial resistance at short times. We also perform WHAM with molecular dynamics simulation and do not find any evidence of an energy barrier or low-diffusivity zone near the interface. Nor do we find evidence from simulation that pre-micellar aggregation slows diffusion enough to cause the observed resistance to interfacial adsorption. We are therefore unable to pinpoint the cause of the resistance, but we suggest that “dead time” associated with the experimental method could be responsible – specifically local depletion of surfactant by the ejected droplet when creating the fresh oil/water interface. In the third approach, we compute desorption rates for isolated polymers stuck to a solid wall with forward flux sampling (FFS). We interpret computed rates on the basis of a conjecture that a dimensionless desorption time scales with the equilibrium ratio of adsorbed surface amount to bulk concentration. We find that the dimensionless desorption time… Advisors/Committee Members: Larson, Ronald G (committee member), Violi, Angela (committee member), Solomon, Michael J (committee member), Ziff, Robert M (committee member).

Subjects/Keywords: surfactant; rare event sampling; molecular simulation; transport phenomena; free energy calculation; Chemical Engineering; Engineering

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APA (6^th Edition):

Huston, K. (2018). Linking the Continuum and Molecular Scales of Adsorption Modeling for Non-Ionic Small Molecules and Homopolymers. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/144112

Chicago Manual of Style (16^th Edition):

Huston, Kyle. “Linking the Continuum and Molecular Scales of Adsorption Modeling for Non-Ionic Small Molecules and Homopolymers.” 2018. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/144112.

MLA Handbook (7^th Edition):

Huston, Kyle. “Linking the Continuum and Molecular Scales of Adsorption Modeling for Non-Ionic Small Molecules and Homopolymers.” 2018. Web. 10 Apr 2021.

Vancouver:

Huston K. Linking the Continuum and Molecular Scales of Adsorption Modeling for Non-Ionic Small Molecules and Homopolymers. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/144112.

Council of Science Editors:

Huston K. Linking the Continuum and Molecular Scales of Adsorption Modeling for Non-Ionic Small Molecules and Homopolymers. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/144112

23. Ni, Peng. Copper Diffusion in Silicate Melts and Melt Inclusion Study on Volatiles in The Lunar Interior.

Degree: PhD, Earth and Environmental Sciences, 2017, University of Michigan

URL: http://hdl.handle.net/2027.42/138482

► This thesis focuses on the application of diffusion kinetics to both terrestrial and lunar geochemistry. In Chapters II and III, diffusivities of Cu in silicate… (more)

▼ This thesis focuses on the application of diffusion kinetics to both terrestrial and lunar geochemistry. In Chapters II and III, diffusivities of Cu in silicate melts were experimentally determined and used to discuss the role of Cu diffusion in formation of Cu ore deposits and also Cu isotope fractionation in tektites. In Chapters IV and V, lunar olivine-hosted melt inclusions are studied to understand their volatile loss during homogenization in lab, to estimate cooling rate for lunar Apollo sample 74220, and to estimate volatile abundance in the lunar mantle. Magmatic sulfide deposits and porphyry-type Cu deposits are two major types of Cu deposits that supply the world’s Cu. In particular, porphyry-type Cu deposits provide ~57% of the world’s total discovered Cu. Recent studies suggest a potential role of diffusive transport of metals (e.g. Cu, Au, PGE, Mo) in the formation of magmatic sulfide deposits and porphyry-type deposits. Diffusivities of Cu in silicate melts, however, are poorly determined. In Chapters II and III of this thesis, Cu diffusion in basaltic melt and rhyolitic melts are studied by diffusion couple and chalcocite “dissolution” methods. Our results indicate high diffusivities of Cu and a general equation for Cu diffusion in silicate melts is obtained. The high diffusivity of Cu indicate that partition of Cu between the silicate phase and the sulfide or fluid phase can be assumed to be in equilibrium during the formation of magmatic sulfide deposits or porphyry-type deposits. In addition, our Cu diffusion data helps explain why Cu isotopes are more fractionated than Zn isotopes in tektites. Volatile abundances in the lunar mantle have profound implications for the origin of the Moon, which was thought to be bone-dry till about a decade ago, when trace amounts of H2O were detected in various types of lunar samples. In particular, high H2O concentrations comparable to mid-ocean ridge basalts were reported in lunar melt inclusions. There are still uncertainties, however, for lunar melt inclusion studies in at least two aspects. One is whether the low H2O/Ce ratios measured in homogenized crystalline inclusions are affected by the homogenization process. The other is that current estimation of volatile abundances in lunar mantle relies heavily on 74220, which is argued to be a local anomaly by some authors. In order to reach a conclusive answer on volatile abundances in lunar mantle, the above two questions have to be answered. To improve our understanding about these questions, in Chapter IV of this thesis, a series of experiments are carried out to understand possible volatile loss from lunar melt inclusions during homogenization. Our results indicate significant H2O loss from inclusions during homogenization in minutes, whereas loss of F, Cl or S is unlikely a concern under our experimental conditions. The most applicable way to preserve H2O during homogenization is to use large inclusions. In Chapter V of this thesis, volatile, trace and major element data for melt inclusions from 10020,… Advisors/Committee Members: Zhang, Youxue (committee member), Violi, Angela (committee member), Lange, Rebecca Ann (committee member), Li, Jie (committee member), Simon, Adam Charles (committee member).

Subjects/Keywords: Geochemical kinetics; Experimental petrology; Diffusion; Water on Moon; Geology and Earth Sciences; Science

…measurements using a Perkin-Elmer Spectrum GX FTIR spectrometer at the University of Michigan. 12… …a piston-cylinder apparatus at the University of Michigan. An illustration of the… …the Cameca SX-100 electron microprobe at the University of Michigan. Major oxide…

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APA (6^th Edition):

Ni, P. (2017). Copper Diffusion in Silicate Melts and Melt Inclusion Study on Volatiles in The Lunar Interior. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/138482

Chicago Manual of Style (16^th Edition):

Ni, Peng. “Copper Diffusion in Silicate Melts and Melt Inclusion Study on Volatiles in The Lunar Interior.” 2017. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/138482.

MLA Handbook (7^th Edition):

Ni, Peng. “Copper Diffusion in Silicate Melts and Melt Inclusion Study on Volatiles in The Lunar Interior.” 2017. Web. 10 Apr 2021.

Vancouver:

Ni P. Copper Diffusion in Silicate Melts and Melt Inclusion Study on Volatiles in The Lunar Interior. [Internet] [Doctoral dissertation]. University of Michigan; 2017. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/138482.

Council of Science Editors:

Ni P. Copper Diffusion in Silicate Melts and Melt Inclusion Study on Volatiles in The Lunar Interior. [Doctoral Dissertation]. University of Michigan; 2017. Available from: http://hdl.handle.net/2027.42/138482

24. Chae, Kyungchan. Mass Diffusion and Chemical Kinetic Data for Jet Fuel Surrogates.

Degree: PhD, Mechanical Engineering, 2010, University of Michigan

URL: http://hdl.handle.net/2027.42/78769

► The predictive capability of combustion modeling is directly related to the accuracy of the models and data used for molecular transport and chemical kinetics. In… (more)

▼ The predictive capability of combustion modeling is directly related to the accuracy of the models and data used for molecular transport and chemical kinetics. In this work, we report on improvements in both categories. The gas kinetic theory (GKT) has been widely used to determine the transport properties of gas-phase molecules because of its simplicity and the lack of experimental data, especially at high temperatures. The major focus of this thesis is to determine the transport properties of complex molecules and suggest an alternative way to overcome the limitations of GKT, especially for large polyatomic molecules. We also recommend a correction term to the expression of the diffusion coefficients that allows the expansion of the validity of the GKT to include molecules with complex geometries and systems at high temperatures. We compute the diffusion coefficients for three classes of hydrocarbons (linear alkanes, cycloalkanes and aromatic molecules) using Molecular Dynamics (MD) simulations with all-atom potentials to incorporate the effects of molecular configurations. The results are compared with the values obtained using GKT, showing that the latter theory overestimates the diffusion of large polyatomic molecules and the error increases for molecules of significantly non-spherical shape. A detailed analysis of the relative importance of the potentials used for MD simulations and the structures of the molecules highlights the importance of the molecular shape in evaluating accurate diffusion coefficients. We also proposed a correction term for the collision diameter used in GKT, based on the radii of gyration of molecules. In the field of chemical kinetics, we report on the reaction mechanisms for the decomposition of decalin, one of the main components of jet fuel surrogates. We identify fifteen reaction pathways and determine the reaction rates using ab-initio techniques and transition state theory. The new kinetic mechanism of decalin is used to study the combustion of decalin showing the importance of the new reactions in predicting combustion products. Advisors/Committee Members: Violi, Angela (committee member), Elvati, Paolo (committee member), Im, Hong G. (committee member), Lastoskie, Christian M. (committee member), Wooldridge, Margaret S. (committee member).

Subjects/Keywords: Mass Diffusion Coefficients; Mechanical Engineering; Engineering

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APA (6^th Edition):

Chae, K. (2010). Mass Diffusion and Chemical Kinetic Data for Jet Fuel Surrogates. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/78769

Chicago Manual of Style (16^th Edition):

Chae, Kyungchan. “Mass Diffusion and Chemical Kinetic Data for Jet Fuel Surrogates.” 2010. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/78769.

MLA Handbook (7^th Edition):

Chae, Kyungchan. “Mass Diffusion and Chemical Kinetic Data for Jet Fuel Surrogates.” 2010. Web. 10 Apr 2021.

Vancouver:

Chae K. Mass Diffusion and Chemical Kinetic Data for Jet Fuel Surrogates. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/78769.

Council of Science Editors:

Chae K. Mass Diffusion and Chemical Kinetic Data for Jet Fuel Surrogates. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/78769

25. Gupta, Saurabh. High-Fidelity Simulation and Analysis of Ignition Regimes and Mixing Characteristics for Low Temperature Combustion Engine Applications.

Degree: PhD, Mechanical Engineering, 2012, University of Michigan

URL: http://hdl.handle.net/2027.42/93944

► Computational singular perturbation (CSP) technique is applied as an automated diagnostic tool to classify ignition regimes in low temperature combustion (LTC) engine environments. Various problems… (more)

▼ Computational singular perturbation (CSP) technique is applied as an automated diagnostic tool to classify ignition regimes in low temperature combustion (LTC) engine environments. Various problems representing LTC are simulated using high-fidelity computation with detailed chemistry for hydrogen-air, and the simulation data are then analyzed by CSP. The active reaction zones are first identified by the locus of minimum number of fast exhausted time scales. Subsequently, the relative importance of transport and chemistry is determined in the region ahead of the reaction zone. A new index I T , defined as the sum of the absolute values of the importance indices of diffusion and convection of temperature to the slow dynamics of temperature, serves as a criterion to differentiate spontaneous ignition from deflagration regimes. The same strategy is then used to classify ignition regimes in n-heptane air mixtures. Parametric studies are conducted using high-fidelity simulations with detailed chemistry and transport. The mixture at non-NTC conditions shows initially a deflagration front which is subsequently transitioned into a spontaneous ignition front. For the mixtures at the NTC conditions which exhibit two-stage ignition behavior, the 1st stage ignition front is found to be more likely in the deflagration regime. On the other hand, the 2nd stage ignition front occurs almost always in the spontaneous regime because the upstream mixture contains active radical species produced by the preceding 1st stage ignition front. The effects of differently correlated equivalence ratio stratification are also considered and the results are shown to be consistent with previous findings. 2D turbulent auto-ignition problems corresponding to NTC and non-NTC chemistry yield similar qualitative results. Finally, we look into the modeling of turbulent mixing, in particular, the scalar dissipation rate, in the context of flamelet approach. This involves a number of aspects: (i) probability density functions, (ii) mean scalar dissipation rates, and (iii) conditional scalar dissipation rates, for mixture fraction (Z) and total enthalpy (H). The validity of existing models both in the RANS and LES contexts is assessed, and alternative models are proposed to improve on the above three aspects. Advisors/Committee Members: Im, Hong G. (committee member), Ihme, Matthias (committee member), Atreya, Arvind (committee member), Valorani, Mauro (committee member), Violi, Angela (committee member).

Subjects/Keywords: Low Temperature Combustion (LTC); Computational Singular Perturbation (CSP); Ignition Regimes; Scalar Dissipation Rate Modeling; Direct Numerical Simulation (DNS); Mechanical Engineering; Engineering

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APA (6^th Edition):

Gupta, S. (2012). High-Fidelity Simulation and Analysis of Ignition Regimes and Mixing Characteristics for Low Temperature Combustion Engine Applications. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/93944

Chicago Manual of Style (16^th Edition):

Gupta, Saurabh. “High-Fidelity Simulation and Analysis of Ignition Regimes and Mixing Characteristics for Low Temperature Combustion Engine Applications.” 2012. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/93944.

MLA Handbook (7^th Edition):

Gupta, Saurabh. “High-Fidelity Simulation and Analysis of Ignition Regimes and Mixing Characteristics for Low Temperature Combustion Engine Applications.” 2012. Web. 10 Apr 2021.

Vancouver:

Gupta S. High-Fidelity Simulation and Analysis of Ignition Regimes and Mixing Characteristics for Low Temperature Combustion Engine Applications. [Internet] [Doctoral dissertation]. University of Michigan; 2012. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/93944.

Council of Science Editors:

Gupta S. High-Fidelity Simulation and Analysis of Ignition Regimes and Mixing Characteristics for Low Temperature Combustion Engine Applications. [Doctoral Dissertation]. University of Michigan; 2012. Available from: http://hdl.handle.net/2027.42/93944

26. Kim, Doohyun. Conventional and Alternative Jet Fuels for Diesel Combustion: Surrogate Development and Insights into the Effect of Fuel Properties on Ignition.

Degree: PhD, Mechanical Engineering, 2016, University of Michigan

URL: http://hdl.handle.net/2027.42/120818

► The use of kerosene-based jet fuels for all military applications has been mandated by U.S. military’s single fuel forward concept. Recently, interest in non-petroleum-derived alternative… (more)

▼ The use of kerosene-based jet fuels for all military applications has been mandated by U.S. military’s single fuel forward concept. Recently, interest in non-petroleum-derived alternative jet fuels has also been increasing as a way to diversify the source of jet fuels. Computational Fluid Dynamics (CFD) simulations with detailed kinetic modeling can be used to model the combustion behavior of real fuel and predict their performance. This thesis revolves around the development of a surrogate mixture for real jet fuels, kinetic models for the surrogate components, and CFD simulations of diesel engines to assess the effects of surrogate’s chemical and physical properties on fundamental combustion processes. Fuel surrogates are mixtures of one or more simple fuels that are designed to emulate key properties of a more complex fuel. For the first time we report on a comprehensive jet fuel surrogates that successfully emulate physical and chemical properties of conventional and alternative jet fuels. To identify the target properties that need to be used to reproduce the diesel combustion, in the first part of this dissertation, a sensitivity analysis was conducted with CFD simulations of pure n-dodecane spray in a constant volume chamber to identify temperature dependent liquid physical properties that are of significance to the diesel ignition process. Out of six physical properties that were tested, density, viscosity, volatility, and specific heat showed major impact on liquid penetration length and ignition delay time. Using a six-component surrogate palette (n-dodecane, n-decane, iso-cetane, iso-octane, decalin, and toluene), the surrogate optimizer generated surrogate mixtures for Jet-A POSF-4658, a petroleum-derived conventional jet fuel, IPK POSF-5642, a coal-derived synthetic jet fuel, and S-8 POSF-4734, a natural-gas-derived synthetic jet fuel. Kinetic modeling of the surrogate fuels were enabled by a detailed chemical mechanism. Numerical experiments were conducted using CFD simulations to evaluate the importance of physical and chemical properties of surrogates on the ignition process of the fuel spray for two fuels. This study indicates that the chemical properties of fuel are much more important to the duration of the ignition delay period than the physical properties, which emphasizes the chemical aspect of the diesel ignition phenomena. Advisors/Committee Members: Violi, Angela (committee member), Martz, Jason Brian (committee member), Gamba, Mirko (committee member), Schihl, Peter Joseph (committee member), Assanis, Dionissios N (committee member).

Subjects/Keywords: fuel surrogate development; diesel combustion; Mechanical Engineering; Engineering

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APA (6^th Edition):

Kim, D. (2016). Conventional and Alternative Jet Fuels for Diesel Combustion: Surrogate Development and Insights into the Effect of Fuel Properties on Ignition. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/120818

Chicago Manual of Style (16^th Edition):

Kim, Doohyun. “Conventional and Alternative Jet Fuels for Diesel Combustion: Surrogate Development and Insights into the Effect of Fuel Properties on Ignition.” 2016. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/120818.

MLA Handbook (7^th Edition):

Kim, Doohyun. “Conventional and Alternative Jet Fuels for Diesel Combustion: Surrogate Development and Insights into the Effect of Fuel Properties on Ignition.” 2016. Web. 10 Apr 2021.

Vancouver:

Kim D. Conventional and Alternative Jet Fuels for Diesel Combustion: Surrogate Development and Insights into the Effect of Fuel Properties on Ignition. [Internet] [Doctoral dissertation]. University of Michigan; 2016. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/120818.

Council of Science Editors:

Kim D. Conventional and Alternative Jet Fuels for Diesel Combustion: Surrogate Development and Insights into the Effect of Fuel Properties on Ignition. [Doctoral Dissertation]. University of Michigan; 2016. Available from: http://hdl.handle.net/2027.42/120818

27. Lacey, Joshua S. The Effects of Advanced Fuels and Additives on Homogeneous Charge Compression Ignition Combustion and Deposit Formation.

Degree: PhD, Mechanical Engineering, 2013, University of Michigan

URL: http://hdl.handle.net/2027.42/97863

► HCCI combustion is highly dependent on in-cylinder thermal conditions and the chemical kinetics of the fuel. In addition to the impact on auto-ignition, the fuel… (more)

▼ HCCI combustion is highly dependent on in-cylinder thermal conditions and the chemical kinetics of the fuel. In addition to the impact on auto-ignition, the fuel properties will also affect the accumulation of deposits on the combustion chamber walls, and this in turn alters the in-cylinder thermal environment. Because the fuels available at the pump differ considerably in composition, strategies intended to bring the HCCI to market must account for the interplay between the fuel chemical components, the HCCI combustion event, and the deposit accumulation in the engine. In an effort to quantify the impacts of fuel composition on HCCI combustion, a large test matrix of fuel blends was investigated in a single-cylinder HCCI engine with re-induction of residual. These fuels were blended from pure refinery streams in an effort to reproduce expected variations of pump gasoline, and were oxygenated with 10% ethanol. The matrix has three dimensions, i.e. the fraction of Olefins (O), the fraction of Aromatics (A), and the Sensitivity (S), defined as the difference between the RON and MON (RON-MON). The impact of fuel composition on performance and thermal efficiency was investigated in a systematic way, such that the obvious impact of the lower heating value is compensated for. The effect of fuel composition and additive packages on HCCI combustion chamber deposit formation was investigated with a second set of refinery stream fuels. The equilibrium CCD thickness was shown to be on the order of 250 micrometers for a highly Aromatic fuel, which is three to five times more than in the case of a low-Aromatic fuel. The subsequent part of the deposit formation study considered two additive packages, namely polybutene amine (PBA) and polyether amine (PEA). The PEA package helped to reduce in-cylinder thickness while the PBA package promoted growth. Finally, microscopic, spectroscopic and diffractometric techniques were employed to quantify physical structure, morphology, chemical composition, and porosity of deposits formed with different fuels and/or additive packages. It is shown that the morphological and chemical dissimilarities among CCD formed with different fuels and additives are not as important to the HCCI combustion event as is the overall thickness. Advisors/Committee Members: Violi, Angela (committee member), Filipi, Zoran S. (committee member), Driscoll, James F. (committee member), Hoard, John W. (committee member), Savage, Phillip E. (committee member).

Subjects/Keywords: HCCI Fuels and Deposits Study; Mechanical Engineering; Engineering

…of similar geometry using our baseline RD3-87 fuel, in a previous University of Michigan…

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APA (6^th Edition):

Lacey, J. S. (2013). The Effects of Advanced Fuels and Additives on Homogeneous Charge Compression Ignition Combustion and Deposit Formation. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/97863

Chicago Manual of Style (16^th Edition):

Lacey, Joshua S. “The Effects of Advanced Fuels and Additives on Homogeneous Charge Compression Ignition Combustion and Deposit Formation.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/97863.

MLA Handbook (7^th Edition):

Lacey, Joshua S. “The Effects of Advanced Fuels and Additives on Homogeneous Charge Compression Ignition Combustion and Deposit Formation.” 2013. Web. 10 Apr 2021.

Vancouver:

Lacey JS. The Effects of Advanced Fuels and Additives on Homogeneous Charge Compression Ignition Combustion and Deposit Formation. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/97863.

Council of Science Editors:

Lacey JS. The Effects of Advanced Fuels and Additives on Homogeneous Charge Compression Ignition Combustion and Deposit Formation. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/97863

28. Ahn, Kyung Ho. Estimation of Ethanol Content and Control of Air-to-Fuel Ratio in Flex Fuel Vehicles.

Degree: PhD, Mechanical Engineering, 2011, University of Michigan

URL: http://hdl.handle.net/2027.42/84549

► Currently available flexible fuel vehicles (FFVs can operate on a blend of gasoline and ethanol in any concentration of up to 85% ethanol (93% in… (more)

▼ Currently available flexible fuel vehicles (FFVs can operate on a blend of gasoline and ethanol in any concentration of up to 85% ethanol (93% in Brazil). Accurate estimation of ethanol content is important to cope with potential problems caused by fuel variability. This thesis provides the first-ever comprehensive collection of models, model-based analysis and control design for ethanol estimation in FFVs. The common practice in ethanol content estimation exploits the differences in stoichiometric air-to-fuel ratios (SAFR) between gasoline and ethanol. In this approach, the online identification of SAFR depends on air and fuel metering during the closed-loop regulation of air-to-fuel ratio (AFR) to the stoichiometric value via the feedback of the exhaust gas oxygen sensor (EGO) measurement. In this thesis, first, we develop a simple phenomenological model of the AFR control process and a simple ethanol estimation law which represents the currently practiced system in FFVs. We then show that the SAFR-based ethanol estimation is sensitive to mass air flow (MAF) sensor drifts and/or fuel injector drifts. A physics-based control-oriented model for fuel puddle dynamics in port fuel injection (PFI) FFVs is then proposed. The transient fuel compensation (TFC) derived from this model allows faster ethanol estimation and improved AFR control. Since the conventional SAFR-based ethanol content estimation is sensitive to MAF sensor error, a method to correct MAF sensor error is next proposed. The correction is realized by using additional measurements of the intake manifold pressure to prevent mis-estimation of ethanol content during MAF sensor drifts. Finally, an integrated estimation scheme in direct injection (DI) FFVs is formulated. This process is able to estimate not only ethanol content but also fuel injector drift. Further, it exploits the difference in latent heat of vaporization (LHV) between gasoline and ethanol by using in-cylinder pressure measurements in addition to conventional SAFR-based estimation. The proposed algorithm and the associated parameter tuning method take the data-driven model errors into account. Feasibility of the integrated estimation scheme is validated by simulations and engine dynamometer tests. Advisors/Committee Members: Stefanopoulou, Anna G. (committee member), Filipi, Zoran S. (committee member), Jankovic, Mrdjan (committee member), Sun, Jing (committee member), Violi, Angela (committee member).

Subjects/Keywords: Ethanol Content Estimation; Flex Fuel; AFR Control; Fuel Puddle; Charge Cooling; In-cylinder Pressure; Mechanical Engineering; Engineering

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APA (6^th Edition):

Ahn, K. H. (2011). Estimation of Ethanol Content and Control of Air-to-Fuel Ratio in Flex Fuel Vehicles. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/84549

Chicago Manual of Style (16^th Edition):

Ahn, Kyung Ho. “Estimation of Ethanol Content and Control of Air-to-Fuel Ratio in Flex Fuel Vehicles.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/84549.

MLA Handbook (7^th Edition):

Ahn, Kyung Ho. “Estimation of Ethanol Content and Control of Air-to-Fuel Ratio in Flex Fuel Vehicles.” 2011. Web. 10 Apr 2021.

Vancouver:

Ahn KH. Estimation of Ethanol Content and Control of Air-to-Fuel Ratio in Flex Fuel Vehicles. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/84549.

Council of Science Editors:

Ahn KH. Estimation of Ethanol Content and Control of Air-to-Fuel Ratio in Flex Fuel Vehicles. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/84549

29. Tsai, Chung-Yin. A Computational Model for Pyrolysis, Heat Transfer, and Combustion in a Fixed-bed Waste Gasifier.

Degree: PhD, Mechanical Engineering, 2011, University of Michigan

URL: http://hdl.handle.net/2027.42/84482

► The overarching goal of the study presented in this dissertation is to develop a predictive computational model that can describe the detailed chemical and physical… (more)

▼ The overarching goal of the study presented in this dissertation is to develop a predictive computational model that can describe the detailed chemical and physical processes associated with pyrolysis, heat transfer and combustion for solid waste in a fixed bed gasifier. The work is applicable to optimization and prediction of the synthetic gas composition of solid waste gasifier operations. The dissertation is comprised of two main parts. In the first part, a predictive three-dimensional model for municipal solid waste gasification process is developed. The multiphase flow is described by a porous flow model using the SIMPLE algorithm with momentum interpolation. The governing equations are transformed into a generalized coordinate system to be applicable to realistic reactor geometry. A simplified global reaction mechanism is adapted for the gas-phase chemical reactions inside the gasifier. The pyrolysis process is described by a phenomenological Lagrangian pyrolysis model to determine the local porosity distribution and the corresponding pyrolysis rate of the waste. Computational results show three-dimensional distribution of the flow field, temperature, species concentration, porosity and the stack morphology under different parametric conditions. The effects of the inlet temperature and the feeding rate on the waste stack shape are studied. The results demonstrate that the model can properly capture the essential physical and chemical processes in the gasifier and thus can be used as a predictive simulation tool. In the second part, the Lagrangian pyrolysis model is extended to consider a multiple characteristic diameter (MCD) pyrolysis submodel in order to independently determine the rate of the local devolatilization, drying and charring processes associated with realistic biomass fuels. The porosity distribution is determined by introducing the local characteristic diameter of the virtual solid spheres representing the biomass fuel. Global homogeneous and heterogeneous reactions were adapted for the chemical reactions inside the gasifier. Synthetic gas compositions from model prediction are validated experiments conducted by Korean Institute of Energy Research (KIER) with good agreements. Model predictions are also compared with the results calculated by the equilibrium model in order to demonstrate that the proposed model improves the predictive capability of the complex nonequilibrium processes inside the gasifier. Advisors/Committee Members: Im, Hong G. (committee member), Atreya, Arvind (committee member), Driscoll, James F. (committee member), Kim, Taig-Young (committee member), Violi, Angela (committee member).

Subjects/Keywords: Biomass Gasification Modeling; Refuse-derived Fuel; Wood Pyrolysis; Devolatilization; Mechanical Engineering; Engineering

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APA (6^th Edition):

Tsai, C. (2011). A Computational Model for Pyrolysis, Heat Transfer, and Combustion in a Fixed-bed Waste Gasifier. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/84482

Chicago Manual of Style (16^th Edition):

Tsai, Chung-Yin. “A Computational Model for Pyrolysis, Heat Transfer, and Combustion in a Fixed-bed Waste Gasifier.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/84482.

MLA Handbook (7^th Edition):

Tsai, Chung-Yin. “A Computational Model for Pyrolysis, Heat Transfer, and Combustion in a Fixed-bed Waste Gasifier.” 2011. Web. 10 Apr 2021.

Vancouver:

Tsai C. A Computational Model for Pyrolysis, Heat Transfer, and Combustion in a Fixed-bed Waste Gasifier. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/84482.

Council of Science Editors:

Tsai C. A Computational Model for Pyrolysis, Heat Transfer, and Combustion in a Fixed-bed Waste Gasifier. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/84482

30. Lai, Jason Yue Wai. Stochastic Simulation of Carbonaceous Nanoparticle Precursor Formation in Combustion.

Degree: PhD, Mechanical Engineering, 2014, University of Michigan

URL: http://hdl.handle.net/2027.42/107094

► Combustion-generated nanoparticles (diameter less than or equal to 100 nm) are prevalent in modern society. Carbonaceous nanoparticles (CNPs) are especially important, finding applications as pigments… (more)

▼ Combustion-generated nanoparticles (diameter less than or equal to 100 nm) are prevalent in modern society. Carbonaceous nanoparticles (CNPs) are especially important, finding applications as pigments in ink, in composite materials, or as catalysts. Despite such useful applications, CNPs have attracted the most attention as hazardous emissions from combustion sources like automotive engines, especially as aggregate particles known as soot, as their primary constituents are carcinogenic polycyclic aromatic hydrocarbons (PAHs). Critically, the formation of CNPs in combustion environments remains an area of considerable uncertainty, particularly the growth from gas phase precursors through the nucleation of solid phase particles. Towards elucidating PAH formation via chemical reactions, a significant element of the growth process, a novel simulation software was developed, named the Stochastic Nanoparticle Simulator (SNAPS), along with a corresponding PAH chemical reaction mechanism. This software was then applied to investigate the chemical and physical properties of PAHs formed in combustion. SNAPS simulations were corroborated through comparisons with existing experimental measurements in flames utilizing a variety of fuels. Furthermore, simulations provided molecular-level detail that revealed key aspects of a complex chemical growth process. Importantly, these simulations provided insights into chemical reaction and composition details beyond those typically inaccessible by experiment. For all studied flames, analysis of the major chemical reactions and PAH species involved in simulations contrasted with conventional theories. Simulations showed that PAH growth is characterized by complex sequences of highly reversible reactions, leading to a variety of species that far exceeds the relatively narrow range that has traditionally been the focus of investigations. SNAPS therefore represents an important tool for synthesizing experimental observations and theoretical predictions, towards building a comprehensive and accurate description of CNP growth. Most importantly, the current work is only one application of the software. The extensibility of SNAPS will enable modeling of many different systems involving heterogeneous nucleation and growth of nanoparticles, which illustrates its potential for wide impact. Altogether, this work represents a strong framework that will support and drive future investigations of nanoparticle growth and contribute to the development of novel combustion technologies that will positively impact society. Advisors/Committee Members: Violi, Angela (committee member), Barker, John R. (committee member), Atreya, Arvind (committee member), Boehman, Andre L. (committee member), Elvati, Paolo (committee member).

Subjects/Keywords: Stochastic Simulation; Carbonaceous Nanoparticles; Chemical Kinetics; Soot; Polycyclic Aromatic Hydrocarbons; Nucleation; Chemical Engineering; Mechanical Engineering; Chemistry; Engineering; Science

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APA (6^th Edition):

Lai, J. Y. W. (2014). Stochastic Simulation of Carbonaceous Nanoparticle Precursor Formation in Combustion. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/107094

Chicago Manual of Style (16^th Edition):

Lai, Jason Yue Wai. “Stochastic Simulation of Carbonaceous Nanoparticle Precursor Formation in Combustion.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/107094.

MLA Handbook (7^th Edition):

Lai, Jason Yue Wai. “Stochastic Simulation of Carbonaceous Nanoparticle Precursor Formation in Combustion.” 2014. Web. 10 Apr 2021.

Vancouver:

Lai JYW. Stochastic Simulation of Carbonaceous Nanoparticle Precursor Formation in Combustion. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/107094.

Council of Science Editors:

Lai JYW. Stochastic Simulation of Carbonaceous Nanoparticle Precursor Formation in Combustion. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/107094

Open Access Theses and Dissertations