+publisher:"University of Michigan" +contributor:("Assanis, Dionissios N")

University of Michigan

1. Chang, Kyoungjoon. Modeling and analysis of an HCCI engine during thermal transients using a thermodynamic cycle simulation with a coupled wall thermal network.

Degree: PhD, Mechanical engineering, 2007, University of Michigan

URL: http://hdl.handle.net/2027.42/126379

► This computational study addresses the unique characteristics of the strong coupling that exists between the thermal condition of the engine structure and the combustion in… (more)

▼ This computational study addresses the unique characteristics of the strong coupling that exists between the thermal condition of the engine structure and the combustion in a Homogeneous Charge Compression Ignition (HCCI) engine, with particular emphasis on the effects of thermal inertia and possible control strategies to compensate for the thermal non-equilibrium that occurs. The engine modeled is a single-cylinder HCCI engine with a re-breathing exhaust valve configuration that utilizes a large amount of hot residual to increase thermal energy of the air-fuel mixture for auto-ignition and to dilute it for preventing rapid heat release rate as well as to keep burned gas temperature low for NO_x control. The in-cylinder combustion and heat transfer, the gas exchange process through valves, and thermal inertia of the engine structures are considered simultaneously in order to fully investigate the HCCI engine transient behavior. A system level engine model including original combustion and heat transfer models developed for the HCCI engine was developed for this purpose. The original contribution of this study is the addition of a thermal network model that tracks the behavior of the engine's thermal boundaries during transient operation. The combustion and performance of an HCCI engine were found to be very sensitive to the engine thermal conditions including intake air temperature, residual level and coolant temperature. In particular, the transient wall temperature excursions from steady-state values were shown to play a great role in determining the combustion characteristics by reducing or enhancing the wall heat transfer. A stable steady-state HCCI operating range was defined and optimized for the best fuel economy by controlling the residual level, and possible shifts of the operating limits due to thermal transitions were studied. An original method was proposed to modulate the role of thermal inertia on auto-ignition during transients by compensating for thermally non-equilibrium wall conditions to enhance robust control of ignition timing in transient operation. A variable valve system was used for that purpose to control combustion phasing by optimizing residual level. The results were improved fuel economy while complying with knock and misfire limits. Advisors/Committee Members: Assanis, Dionissios N. (advisor).

Subjects/Keywords: Analysis; Coupled; Engine; Hcci; Homogeneous Charge Compression Ignition; Homogeneous Charge-compression Ignition; Modeling; Network; Simulation; Thermal Transients; Thermodynamic Cycle; Using; Wall

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APA (6^th Edition):

Chang, K. (2007). Modeling and analysis of an HCCI engine during thermal transients using a thermodynamic cycle simulation with a coupled wall thermal network. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/126379

Chicago Manual of Style (16^th Edition):

Chang, Kyoungjoon. “Modeling and analysis of an HCCI engine during thermal transients using a thermodynamic cycle simulation with a coupled wall thermal network.” 2007. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/126379.

MLA Handbook (7^th Edition):

Chang, Kyoungjoon. “Modeling and analysis of an HCCI engine during thermal transients using a thermodynamic cycle simulation with a coupled wall thermal network.” 2007. Web. 10 Apr 2021.

Vancouver:

Chang K. Modeling and analysis of an HCCI engine during thermal transients using a thermodynamic cycle simulation with a coupled wall thermal network. [Internet] [Doctoral dissertation]. University of Michigan; 2007. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/126379.

Council of Science Editors:

Chang K. Modeling and analysis of an HCCI engine during thermal transients using a thermodynamic cycle simulation with a coupled wall thermal network. [Doctoral Dissertation]. University of Michigan; 2007. Available from: http://hdl.handle.net/2027.42/126379

University of Michigan

2. Depcik, Christopher David. Modeling reacting gases and aftertreatment devices for internal combustion engines.

Degree: PhD, Mechanical engineering, 2003, University of Michigan

URL: http://hdl.handle.net/2027.42/123823

► As more emphasis is placed worldwide on reducing greenhouse gas emissions, automobile manufacturers have to create more efficient engines. Simultaneously, legislative agencies want these engines… (more)

▼ As more emphasis is placed worldwide on reducing greenhouse gas emissions, automobile manufacturers have to create more efficient engines. Simultaneously, legislative agencies want these engines to produce fewer problematic emissions such as nitrogen oxides and particulate matter. In response, newer combustion methods, like homogeneous charge compression ignition and fuel cells, are being researched alongside the old standard of efficiency, the compression ignition or diesel engine. These newer technologies present a number of benefits but still have significant challenges to overcome. As a result, renewed interest has risen in making diesel engines cleaner. The key to cleaning up the diesel engine is the placement of aftertreatment devices in the exhaust. These devices have shown great potential in reducing emission levels below regulatory levels while still allowing for increased fuel economy versus a gasoline engine. However, these devices are subject to many flow control issues. While experimental evaluation of these devices helps to understand these issues better, it is impossible to solve the problem through experimentation alone because of time and cost constraints. Because of this, accurate models are needed in conjunction with the experimental work. In this dissertation, the author examines the entire exhaust system including reacting gas dynamics and aftertreatment devices, and develops a complete numerical model for it. The author begins by analyzing the current one-dimensional gas-dynamics simulation models used for internal combustion engine simulations. It appears that more accurate and faster numerical method is available, in particular, those developed in aeronautical engineering, and the author successfully implements one for the exhaust system. The author then develops a comprehensive literature search to better understand the aftertreatment devices. A number of these devices require a secondary injection of fuel or reductant in the exhaust stream. Accordingly, the author develops a simple post-cylinder injection model which can be easily tuned to match experimental findings. In addition, the author creates a general catalyst model which can be used to model virtually all of the different aftertreatment devices. Extensive validation of this model with experimental data is presented along with all of the numerical algorithms needed to reproduce the model. Advisors/Committee Members: Assanis, Dionissios N. (advisor).

Subjects/Keywords: Aftertreatment; Catalytic; Devices; Internal Combustion Engines; Modeling; Reacting Gases

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APA (6^th Edition):

Depcik, C. D. (2003). Modeling reacting gases and aftertreatment devices for internal combustion engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/123823

Chicago Manual of Style (16^th Edition):

Depcik, Christopher David. “Modeling reacting gases and aftertreatment devices for internal combustion engines.” 2003. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/123823.

MLA Handbook (7^th Edition):

Depcik, Christopher David. “Modeling reacting gases and aftertreatment devices for internal combustion engines.” 2003. Web. 10 Apr 2021.

Vancouver:

Depcik CD. Modeling reacting gases and aftertreatment devices for internal combustion engines. [Internet] [Doctoral dissertation]. University of Michigan; 2003. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/123823.

Council of Science Editors:

Depcik CD. Modeling reacting gases and aftertreatment devices for internal combustion engines. [Doctoral Dissertation]. University of Michigan; 2003. Available from: http://hdl.handle.net/2027.42/123823

University of Michigan

3. Chryssakis, Christos. A unified fuel spray breakup model for internal combustion engine applications.

Degree: PhD, Mechanical engineering, 2005, University of Michigan

URL: http://hdl.handle.net/2027.42/125326

► A unified approach towards modeling fuel sprays for internal combustion engines has been developed in this work. Based on a Lagrangian approach, the fuel injection… (more)

Subjects/Keywords: Applications; Breakup; Fuel Spray; Internal Combustion Engine; Model; Unified

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Chryssakis, C. (2005). A unified fuel spray breakup model for internal combustion engine applications. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/125326

Chicago Manual of Style (16^th Edition):

Chryssakis, Christos. “A unified fuel spray breakup model for internal combustion engine applications.” 2005. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/125326.

MLA Handbook (7^th Edition):

Chryssakis, Christos. “A unified fuel spray breakup model for internal combustion engine applications.” 2005. Web. 10 Apr 2021.

Vancouver:

Chryssakis C. A unified fuel spray breakup model for internal combustion engine applications. [Internet] [Doctoral dissertation]. University of Michigan; 2005. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/125326.

Council of Science Editors:

Chryssakis C. A unified fuel spray breakup model for internal combustion engine applications. [Doctoral Dissertation]. University of Michigan; 2005. Available from: http://hdl.handle.net/2027.42/125326

University of Michigan

4. Knafl, Alexander. Development of low -temperature premixed diesel combustion strategies and formulation of suitable diesel oxidation catalysts.

Degree: PhD, Mechanical engineering, 2007, University of Michigan

URL: http://hdl.handle.net/2027.42/126465

► The successful development of low-temperature premixed compression ignition (PCI) combustion strategies and formulation of suitable diesel oxidation catalysts (DOC) is presented in this dissertation. Low-temperature… (more)

▼ The successful development of low-temperature premixed compression ignition (PCI) combustion strategies and formulation of suitable diesel oxidation catalysts (DOC) is presented in this dissertation. Low-temperature PCI combustion is shown to reduce engine-out oxides of nitrogen (NO_X) and soot emissions by 74% and 86% respectively at 1500 rpm and 400 kPa brake mean effective pressure (BMEP) over a modern conventional diesel combustion strategy. The PCI load-range is investigated at 1500 rpm between 50 kPa and 720 kPa BMEP. NO_X can be held to 1 g/kg-fuel at all loads. Soot is below 0.015 g/kg-fuel up to 400 kPa BMEP but increases to 1.11 g/kg-fuel at 720 kPa BMEP, thus limiting PCI operation at high engine loads. Excessive carbon monoxide (CO), hydrocarbon (HC) emissions and low exhaust gas temperatures are obtained at 50 kPa BMEP limiting PCI operation at low loads. Eight DOC formulations are investigated on a gas bench reactor using surrogate exhaust gas mixtures containing CO, O₂, H₂O, C₁₁H₂₄. C₂H₄ and N₂. HC speciation of engine exhaust identified n-undecane (C₁₁H₂₄) and ethene (C₂H₄) as the dominant HC species. PCI and conventional light-off and light-down tests are performed. Light-off temperatures are higher in PCI exhaust compared to conventional exhaust. Light-dowel temperatures are lower than light-off temperatures under PCI and conventional conditions. CO and HC are converted to 100% and 98% respectively under fully lit conditions. The addition of ceria to washcoat and an increased washcoat loading show 20°C lower light-off temperature compared to the reference formulation. Formulations containing mixtures of platinum (Pt) and palladium (Pd) outperform Pt-only formulations. Engine experiments agree well with reactor experiments. DOC formulations containing zeolites adsorb HC at low temperatures. HC speciation shows that HCs of carbon number five and higher are trapped on zeolite at low temperatures. CO conversion is 100% through the fully active catalyst; HC conversion is lower compared to the reactor experiments. Methane (CH₄) and HC desorption in the emissions sample system are responsible for the discrepancy. Light-off temperatures are higher in engine experiments compared to reactor experiments due to heat loss and inhibition by CO and unsaturated HC. Advisors/Committee Members: Assanis, Dionissios N. (advisor).

Subjects/Keywords: Catalysts; Combustion; Development; Diesel; Formulation; Low-temperature; Oxidation; Premixed; Strategies; Suitable

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Knafl, A. (2007). Development of low -temperature premixed diesel combustion strategies and formulation of suitable diesel oxidation catalysts. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/126465

Chicago Manual of Style (16^th Edition):

Knafl, Alexander. “Development of low -temperature premixed diesel combustion strategies and formulation of suitable diesel oxidation catalysts.” 2007. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/126465.

MLA Handbook (7^th Edition):

Knafl, Alexander. “Development of low -temperature premixed diesel combustion strategies and formulation of suitable diesel oxidation catalysts.” 2007. Web. 10 Apr 2021.

Vancouver:

Knafl A. Development of low -temperature premixed diesel combustion strategies and formulation of suitable diesel oxidation catalysts. [Internet] [Doctoral dissertation]. University of Michigan; 2007. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/126465.

Council of Science Editors:

Knafl A. Development of low -temperature premixed diesel combustion strategies and formulation of suitable diesel oxidation catalysts. [Doctoral Dissertation]. University of Michigan; 2007. Available from: http://hdl.handle.net/2027.42/126465

University of Michigan

5. Jacobs, Timothy John. Simultaneous reduction of nitric oxide and particulate matter emissions from a light -duty diesel engine using combustion development and diesel oxidation catalyst.

Degree: PhD, Mechanical engineering, 2005, University of Michigan

URL: http://hdl.handle.net/2027.42/124825

► The following document highlights the successful development of a scientifically-based approach for creating diesel engine combustion that yields lower levels of nitric oxide (NO_x) and… (more)

▼ The following document highlights the successful development of a scientifically-based approach for creating diesel engine combustion that yields lower levels of nitric oxide (NO_x) and particulate matter (PM) emissions while minimizing the associated fuel consumption penalty and raised levels of hydrocarbon (HC) and carbon monoxide (CO) emissions. The 93% reduction in NO_x, coupled with the simultaneous 79% reduction in PM places the newly developed engine calibration within the emission targets established for this research development. The primary distinguishable features of this strategy are premixed and low-temperature combustion. Both characteristics shift combustion to a region where simultaneous reductions in NO_x and PM occur, thus defeating the perennial PM-NO_x tradeoff associated with conventional diesel combustion. The increase in fuel consumption, 5% over the studied conventional combustion strategy, could possibly be recovered in part through optimal development of the engine system from the turbocharger to the combustion chamber design. The new combustion development approach opens an opportunity to run the diesel engine rich of stoichiometric air-fuel ratios, while maintaining near-zero EI-PM emissions. Exhaust concentrations of CO as high as 5% emitted from the rich diesel condition create enough of the reducing agent necessary for an aggressive regeneration of a NO_x storage aftertreatment device. The rise in fuel consumption, greater than that associated with the newly developed lean combustion strategy, prevents this condition from usefully serving as a standard operating mode; its intention is to operate only as necessary to maintain high NO_x removal efficiency. Related to this, the 99% reduction in NO_x and 98% reduction in PM – relative to the studied conventional diesel combustion strategy – assist in preventing PM and NO_x interference during the regeneration of a NO_x storage device. Increased levels of HC and CO species result as diesel combustion burns in the new premixed, low-temperature fashion. A diesel oxidation catalyst (DOC) was studied to determine its ability to remove the higher levels of HC and CO species associated with the newly developed combustion strategies. The catalyst-out concentrations of emissions produced from the newly developed lean strategy lessen such that all emissions, i.e. NO_x, PM, CO, and HC, satisfactorily meet the most stringent of upcoming federal emission regulations, at the studied engine speed and load. However, this study postulates that dramatic reductions in combustion temperature at the newly developed rich strategy alter HC species, which thereby completely quench the oxidation activity of the DOC. An increase of 100°C in exhaust temperature or an increase of exhaust oxygen concentration to 2% of total exhaust volume at the rich strategy does not improve the DOC's ability to remove HC or CO. Advisors/Committee Members: Assanis, Dionissios N. (advisor).

Subjects/Keywords: Catalyst; Combustion; Development; Diesel Engine; Duty; Emissions; Light; Nitric Oxide; Oxidation; Particulate Matter; Reduction; Simultaneous; Using

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APA (6^th Edition):

Jacobs, T. J. (2005). Simultaneous reduction of nitric oxide and particulate matter emissions from a light -duty diesel engine using combustion development and diesel oxidation catalyst. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/124825

Chicago Manual of Style (16^th Edition):

Jacobs, Timothy John. “Simultaneous reduction of nitric oxide and particulate matter emissions from a light -duty diesel engine using combustion development and diesel oxidation catalyst.” 2005. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/124825.

MLA Handbook (7^th Edition):

Jacobs, Timothy John. “Simultaneous reduction of nitric oxide and particulate matter emissions from a light -duty diesel engine using combustion development and diesel oxidation catalyst.” 2005. Web. 10 Apr 2021.

Vancouver:

Jacobs TJ. Simultaneous reduction of nitric oxide and particulate matter emissions from a light -duty diesel engine using combustion development and diesel oxidation catalyst. [Internet] [Doctoral dissertation]. University of Michigan; 2005. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/124825.

Council of Science Editors:

Jacobs TJ. Simultaneous reduction of nitric oxide and particulate matter emissions from a light -duty diesel engine using combustion development and diesel oxidation catalyst. [Doctoral Dissertation]. University of Michigan; 2005. Available from: http://hdl.handle.net/2027.42/124825

University of Michigan

6. Babajimopoulos, Aristotelis. Development of sequential and fully integrated CFD/multi-zone models with detailed chemical kinetics for the simulation of HCCI engines.

Degree: PhD, Mechanical engineering, 2005, University of Michigan

URL: http://hdl.handle.net/2027.42/124994

► Modeling the Homogeneous Charge Compression Ignition (HCCI) engine requires a balanced approach that captures both fluid motion as well as low and high temperature fuel… (more)

▼ Modeling the Homogeneous Charge Compression Ignition (HCCI) engine requires a balanced approach that captures both fluid motion as well as low and high temperature fuel oxidation. A fully coupled CFD and chemistry scheme would be the ideal HCCI modeling approach, but is computationally very expensive. As a result, modeling assumptions are required in order to develop tools that are computationally efficient, yet maintain an acceptable degree of accuracy. In the first part of this dissertation, KIVA-3V is used to investigate the mixing process in HCCI engines prior to combustion, particularly for operation with high levels of residual gas fraction. It is found that insufficient mixing of the hot residuals with the fresh charge can lead to the presence of significant temperature and composition nonuniformities in the cylinder. Then, in order to investigate the effect of temperature and composition stratification on HCCI combustion, two modeling approaches are explored. The first approach is a sequential fluid-mechanic - thermo-kinetic model. The KIVA-3V code is initiated before the exhaust event and operated over the gas exchange period, until a transition point before TDC. The three-dimensional computational domain is then mapped into a two-dimensional array of zones with different temperature and composition, which are used to initiate a multi-zone thermodynamic simulation. In the second approach, KIVA-3V is fully integrated with a multi-zone model with detailed chemical kinetics. The multi-zone model communicates with KIVA-3V at each computational timestep, as in the ideal fully coupled case. However, the composition of the cells is mapped back and forth between KIVA-3V and the multi-zone model, introducing significant computational time savings. The methodology uses a novel re-mapping technique that can account for both temperature and composition non-uniformities in the cylinder. Validation cases were developed by solving the detailed chemistry in every cell of a KIVA-3V grid. The new methodology shows good agreement with the detailed solutions. Hence, it can be used to provide insight into the fundamental effects of temperature and equivalence ratio distribution on ignition, burn duration, and emissions in HCCI engines. Advisors/Committee Members: Assanis, Dionissios N. (advisor).

Subjects/Keywords: Cfd; Chemical; Combustion; Detailed; Development; Engines; Fully; Hcci; Homogeneous Charge Compression Ignition; Integrated; Kinetics; Models; Multi; Sequential; Simulation; Zone

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Babajimopoulos, A. (2005). Development of sequential and fully integrated CFD/multi-zone models with detailed chemical kinetics for the simulation of HCCI engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/124994

Chicago Manual of Style (16^th Edition):

Babajimopoulos, Aristotelis. “Development of sequential and fully integrated CFD/multi-zone models with detailed chemical kinetics for the simulation of HCCI engines.” 2005. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/124994.

MLA Handbook (7^th Edition):

Babajimopoulos, Aristotelis. “Development of sequential and fully integrated CFD/multi-zone models with detailed chemical kinetics for the simulation of HCCI engines.” 2005. Web. 10 Apr 2021.

Vancouver:

Babajimopoulos A. Development of sequential and fully integrated CFD/multi-zone models with detailed chemical kinetics for the simulation of HCCI engines. [Internet] [Doctoral dissertation]. University of Michigan; 2005. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/124994.

Council of Science Editors:

Babajimopoulos A. Development of sequential and fully integrated CFD/multi-zone models with detailed chemical kinetics for the simulation of HCCI engines. [Doctoral Dissertation]. University of Michigan; 2005. Available from: http://hdl.handle.net/2027.42/124994

University of Michigan

7. Hamosfakidis, Vasileios. A two conserved scalar model for HCCI and PPCI engine applications.

Degree: PhD, Mechanical engineering, 2007, University of Michigan

URL: http://hdl.handle.net/2027.42/126432

► There is a strong demand for a versatile computational model in the design of modern engines such as homogeneous charge compression ignition (HCCI) and partially… (more)

▼ There is a strong demand for a versatile computational model in the design of modern engines such as homogeneous charge compression ignition (HCCI) and partially premixed compression ignition (PPCI) engines. A robust model is required to describe accurately both the chemistry and turbulent mixing processes in the reacting flow. Although the existing computational fluid dynamics (CFD) codes coupled with detailed kinetics models may reproduce some realistic results, the excessive computational cost prevents them to be applicable as engineering tools. The present study aims at developing a new modeling approach that can describe the combustion process with high fidelity and computational efficiency. In this study, a two-conserved scalar approach is proposed to model HCCI and PPCI combustion. The first conserved scalar, the mixture fraction Z, is introduced to capture the inhomogeneities in the fuel-air mixture, and the second conserved scalar, the initial EGR fraction J, is introduced to capture the inhomogeneities in the fresh mixture-EGR charge. The main benefits of this approach are the reduction of dimensionality and the compactness of the domain in the conserved scalar plane, and the capability to use different resolutions for the chemistry and the fluid mechanics calculation. To solve the flow in the conserved scalar plane, two algorithms are proposed. First, the flamelet (zone) creation strategy is introduced to discretize the conserved scalar space based on its mass distribution and reactivity. The second part is the regeneration procedure which accounts for the nonlinear effect of EGR on reaction rates. Test results from the two-conserved scalar approach are compared to those obtained by direct calculation, and it is demonstrated that the regeneration process in the present approach can properly account for the nonlinear effects arising from chemical reactions, as an improvement over the representative interactive flamelet (RIF) approach. The two conserved scalar model is subsequently implemented into the KIVA-3v code to simulate HCCI combustion. The results show excellent agreement with experimental data, demonstrating that the present approach achieves the initial modeling objectives. Finally, the two conserved scalar approach is applied to the modeling of direct injection (DI) combustion with an assumption of non-homogeneous EGR. Discrepancies relative to the results from direct calculations are identified. These are attributed to the limitation inherent to the flamelet model, and further improvements are suggested as future work. Advisors/Committee Members: Assanis, Dionissios N. (advisor).

Subjects/Keywords: Applications; Conserved; Engine; Hcci; Homogeneous Charge Compression Ignition; Homogeneous Charge-compression Ignition; Model; Partially Premixed Compression Ignition; Ppci; Scalar; Two

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APA (6^th Edition):

Hamosfakidis, V. (2007). A two conserved scalar model for HCCI and PPCI engine applications. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/126432

Chicago Manual of Style (16^th Edition):

Hamosfakidis, Vasileios. “A two conserved scalar model for HCCI and PPCI engine applications.” 2007. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/126432.

MLA Handbook (7^th Edition):

Hamosfakidis, Vasileios. “A two conserved scalar model for HCCI and PPCI engine applications.” 2007. Web. 10 Apr 2021.

Vancouver:

Hamosfakidis V. A two conserved scalar model for HCCI and PPCI engine applications. [Internet] [Doctoral dissertation]. University of Michigan; 2007. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/126432.

Council of Science Editors:

Hamosfakidis V. A two conserved scalar model for HCCI and PPCI engine applications. [Doctoral Dissertation]. University of Michigan; 2007. Available from: http://hdl.handle.net/2027.42/126432

University of Michigan

8. Zeng, Pin. Unsteady convective heat transfer modeling and application to internal combustion engines.

Degree: PhD, Mechanical engineering, 2004, University of Michigan

URL: http://hdl.handle.net/2027.42/124227

► Steady convective heat transfer correlations are widely used to predict heat transfer in the cylinders and manifolds of internal combustion engines. However, previous studies by… (more)

▼ Steady convective heat transfer correlations are widely used to predict heat transfer in the cylinders and manifolds of internal combustion engines. However, previous studies by Overbye et al. (1961), Annand and Pinfold (1980), Kornhauser and Smith (1994), and Bauer et al. (1998) showed that the heat transfer rates are out of phase with gas-wall temperature difference and gas velocity in engine cylinder and manifold. In this study, a dimensional analysis of the unsteady boundary layer governing equations was performed, and two new dimensionless variables were identified. They are related to the changing rates of velocity and temperature. A new concept of dynamic variable that contains information about both the instantaneous value and it changing rate has been introduced to use the dimensionless variables to extend the existing steady heat transfer models into unsteady heat transfer models. From this study, it is found that the heat transfer rate has a phase delay with respect to the fluid velocity variation due to the delay of turbulent intensity from mean flow velocity. This phase delay can be captured by the unsteady heat transfer model for the unsteady velocity correction. It is also found that in a motored engine the heat transfer rates on both sides of the thermal boundary layer have a phase shift. This phase shift can be simulated by the unsteady heat transfer model for the unsteady temperature correction. Furthermore, it is found that when the velocity decreases too fast, turbulent intensity will not follow the velocity's decrease process; rather it starts its own decay process. The heat transfer in the turbulent decay process is the primary contributor to the heat transfer increase from unsteady velocity variation. A criterion has been found for the onset of the turbulent decay process and a model has been developed to predict the turbulent intensity associated with the turbulent decay process. The unsteady heat transfer models developed in this study are validated in a turbulent pipe heat transfer system, an engine intake manifold, and a motored diesel engine. The validation results confirmed the model's ability to capture the unsteady effects of velocity and temperature variations. Advisors/Committee Members: Assanis, Dionissios N. (advisor).

Subjects/Keywords: Application; Convective Heat Transfer; Internal Combustion Engines; Modeling; Unsteady

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zeng, P. (2004). Unsteady convective heat transfer modeling and application to internal combustion engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/124227

Chicago Manual of Style (16^th Edition):

Zeng, Pin. “Unsteady convective heat transfer modeling and application to internal combustion engines.” 2004. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/124227.

MLA Handbook (7^th Edition):

Zeng, Pin. “Unsteady convective heat transfer modeling and application to internal combustion engines.” 2004. Web. 10 Apr 2021.

Vancouver:

Zeng P. Unsteady convective heat transfer modeling and application to internal combustion engines. [Internet] [Doctoral dissertation]. University of Michigan; 2004. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/124227.

Council of Science Editors:

Zeng P. Unsteady convective heat transfer modeling and application to internal combustion engines. [Doctoral Dissertation]. University of Michigan; 2004. Available from: http://hdl.handle.net/2027.42/124227

University of Michigan

9. Grover, Ronald O. A methodology for CFD predictions of spark -ignition direct -injection engine conical sprays combining improved physical submodels and system optimization.

Degree: PhD, Mechanical engineering, 2005, University of Michigan

URL: http://hdl.handle.net/2027.42/124800

► The motivation of this study is to improve the modeling of conical sprays used in Spark Ignition Direct-Injection (SIDI) engines via submodel development and an… (more)

▼ The motivation of this study is to improve the modeling of conical sprays used in Spark Ignition Direct-Injection (SIDI) engines via submodel development and an integrated system optimization approach. Direct-injection combustion strategies have been identified as a possible solution to meet future stringent fuel economy regulations for passenger vehicles. A common fuel injector of choice has been the pressure-swirl atomizer having either an inwardly or outwardly opening nozzle. Several numerical investigations of these injectors have been undertaken over the past decade; however, adequately simulating these sprays over the entire SIDI operating range has posed many challenges. One reason for the discrepancy between CFD simulations and experimental results is the deficiencies in the models describing droplet behavior due to injector design, primary atomization, and secondary atomization. Both the initial spray that emerges from the injector, as well as the primary atomization process, are difficult to model due to a high level of uncertainty in quantifying the controlling physics in a region of the spray where accurate experimental measurements are difficult to obtain. Secondary atomization is complicated by the uncertainty in modeling high-speed droplet breakup due to the combined effects of droplet deformation and momentum coupling with the ambient medium. A unique methodology for improving predictions of high-speed conical sheet sprays is outlined in this document. Initially, the limitations of a select group of submodels will be assessed on a zero-dimensional basis outside of the multidimensional code. From a submodel development standpoint, the physics of the atomization submodels will be enhanced to better represent the physical processes. Next, from a numerical perspective, a physically-based configuration and integration of the entire family of spray submodels within a multidimensional simulation will be evaluated. Finally, an optimization algorithm will be used to improve the accuracy of numerical predictions when compared to various complementary experimental measurements obtained over a wide range of operating conditions. Advisors/Committee Members: Assanis, Dionissios N. (advisor).

Subjects/Keywords: Cfd; Combining; Computational Fluid Dynamics; Conical; Engine; Improved; Methodology; Physical; Predictions; Spark-ignition Direct-injection; Sprays; Submodels; System Optimization

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APA (6^th Edition):

Grover, R. O. (2005). A methodology for CFD predictions of spark -ignition direct -injection engine conical sprays combining improved physical submodels and system optimization. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/124800

Chicago Manual of Style (16^th Edition):

Grover, Ronald O. “A methodology for CFD predictions of spark -ignition direct -injection engine conical sprays combining improved physical submodels and system optimization.” 2005. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/124800.

MLA Handbook (7^th Edition):

Grover, Ronald O. “A methodology for CFD predictions of spark -ignition direct -injection engine conical sprays combining improved physical submodels and system optimization.” 2005. Web. 10 Apr 2021.

Vancouver:

Grover RO. A methodology for CFD predictions of spark -ignition direct -injection engine conical sprays combining improved physical submodels and system optimization. [Internet] [Doctoral dissertation]. University of Michigan; 2005. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/124800.

Council of Science Editors:

Grover RO. A methodology for CFD predictions of spark -ignition direct -injection engine conical sprays combining improved physical submodels and system optimization. [Doctoral Dissertation]. University of Michigan; 2005. Available from: http://hdl.handle.net/2027.42/124800

University of Michigan

10. Triantopoulos, Vasileios. Experimental and Computational Investigation of Spark Assisted Compression Ignition Combustion Under Boosted, Ultra EGR-Dilute Conditions.

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

URL: http://hdl.handle.net/2027.42/147508

► Low temperature combustion (LTC) engines that employ high levels of dilution have received increased research interest due to the demonstrated thermal efficiency improvements compared to… (more)

▼ Low temperature combustion (LTC) engines that employ high levels of dilution have received increased research interest due to the demonstrated thermal efficiency improvements compared to the conventional Spark-Ignited (SI) engines. However, control of combustion phasing and heat release rate still remains a challenge, which limits the operating range as well as the transient operation of LTC engines. The work presented in this dissertation uses experimental and computational methods to investigate Spark Assisted Compression Ignition (SACI) combustion under boosted, stoichiometric conditions with high levels of exhaust gas recirculation in a negative valve overlap engine. Highly controlled experimental studies were performed to understand the impact of intake boosting and fuel-to-charge equivalence ratio (φ') on SACI burn rates, while maintaining constant combustion phasing near the optimal timing for work extraction. Previously unexplored conditions were targeted at intake pressures ranging from 80 kPa to 150 kPa and φ' ranging from 0.45 to 0.75, where LTC engines promise high thermodynamic efficiencies. The use of intake boosting for load expansion and dilution extension achieved up to 10% gross thermal efficiency improvement, respectively, mainly due to reduced relative heat transfer losses and better mixture thermodynamic properties. For a given spark advance, higher pressure and/or higher φ' mixtures necessitated lower unburned gas temperatures (TU) to match autoignition timing. While the overall effect of intake boost was minor on the initial flame burn rates, end-gas autoignition rates were found to approximately scale with intake pressure. Higher φ' mixtures exhibited faster initial flame burn rates but also led to a significant increase in end-gas autoignition rates. As a result, the high load limits shifted to lower φ' at higher intake pressures, creating a larger gap between the SI and SACI operating limits. Reducing the mass fraction unburned at the onset of autoignition by advancing the spark timing and lowering TU was, to some extent, effective at alleviating the excessive peak pressure rise rates. Under relatively high φ' conditions, cyclic heat release analysis results showed that the variability in autoignition timing is determined early in the cycle before any measurable pressure-based heat release. Combustion phasing retard was shown to be very effective at limiting the maximum pressure rise rates until the stability limit, primarily due to slower end-gas autoignition rates. CFD modeling results showed good trendwise agreement with the experimental results, once autoignition timing and mass fraction burned at the onset of autoignition were matched. The pre-ignition reactivity stratification of the mixture at higher intake pressures was shown to be narrower, due to both lower thermal and compositional stratification, which explained the increase in end-gas burn rates observed experimentally. The boost pressure effect on SACI end-gas burn rates using intake manifold heating was trendwise similar… Advisors/Committee Members: Boehman, Andre L (committee member), Gamba, Mirko (committee member), Assanis, Dionissios N (committee member), Bohac, Stani V (committee member), Borgnakke, Claus (committee member), Martz, Jason Brian (committee member).

Subjects/Keywords: engines; thermodynamics; energy; efficiency; automotive; power; Mechanical Engineering; Engineering

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APA (6^th Edition):

Triantopoulos, V. (2018). Experimental and Computational Investigation of Spark Assisted Compression Ignition Combustion Under Boosted, Ultra EGR-Dilute Conditions. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/147508

Chicago Manual of Style (16^th Edition):

Triantopoulos, Vasileios. “Experimental and Computational Investigation of Spark Assisted Compression Ignition Combustion Under Boosted, Ultra EGR-Dilute Conditions.” 2018. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/147508.

MLA Handbook (7^th Edition):

Triantopoulos, Vasileios. “Experimental and Computational Investigation of Spark Assisted Compression Ignition Combustion Under Boosted, Ultra EGR-Dilute Conditions.” 2018. Web. 10 Apr 2021.

Vancouver:

Triantopoulos V. Experimental and Computational Investigation of Spark Assisted Compression Ignition Combustion Under Boosted, Ultra EGR-Dilute Conditions. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/147508.

Council of Science Editors:

Triantopoulos V. Experimental and Computational Investigation of Spark Assisted Compression Ignition Combustion Under Boosted, Ultra EGR-Dilute Conditions. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/147508

University of Michigan

11. Shingne, Prasad Sunand. Thermodynamic Modeling of HCCI Combustion with Recompression and Direct Injection.

Degree: PhD, Mechanical Engineering, 2015, University of Michigan

URL: http://hdl.handle.net/2027.42/113499

► Homogeneous Charge Compression Ignition (HCCI) engines have the potential to reduce pollutant emissions while achieving diesel-like thermal efficiencies. The absence of direct control over the… (more)

▼ Homogeneous Charge Compression Ignition (HCCI) engines have the potential to reduce pollutant emissions while achieving diesel-like thermal efficiencies. The absence of direct control over the start and rate of auto-ignition and a narrow load range makes implementation of HCCI engines into production vehicles a challenging affair. Effective HCCI combustion control can be achieved by manipulating the amount of residual gases trapped from the previous cycle by means of variable valve actuation. In turn, the temperature at intake valve closing and hence auto-ignition phasing can be controlled. Intake charge boosting can be used to increase HCCI fueling rates and loads, while other technologies such as direct injection provide means for achieving cycle to cycle phasing control. Thermodynamic zero-dimensional (0D) models are a computationally inexpensive tool for defining systems and strategies suitable for the implementation of new HCCI engine technologies. These models need to account for the thermal and compositional stratification in HCCI that control combustion rates. However these models are confined to a narrow range of engine operation given that the fundamental factors governing the combustion process are currently not well understood. CFD has therefore been used to understand the effect of operating conditions and input variables on pre-ignition charge stratification and combustion, allowing the development and use of a more accurate ignition model, which is proposed and validated here. A new empirical burn profile model is fit with mass fraction burned profiles from a large HCCI engine data set. The combined ignition model and burn correlation are then exercised and are shown capable of capturing the trends of a diverse range of transient HCCI experiments. However, the small cycle to cycle variations in combustion phasing are not captured by the model, possibly due to recompression heat release effects associated with variable valve actuation. Multi-cycle CFD simulations are therefore performed to gain physical insight into recompression heat release phenomena and the effect of these phenomena on the next cycle. Based on the understanding derived from this CFD work, a simple model of recompression heat release has been implemented in the 0D HCCI modeling framework. Advisors/Committee Members: Martz, Jason Brian (committee member), Assanis, Dionissios N. (committee member), Borgnakke, Claus (committee member), Driscoll, James F. (committee member), Boehman, Andre L. (committee member), Bohac, Stani V. (committee member).

Subjects/Keywords: HCCI; Combustion; Thermodynamics; 0D Modeling; Stratification; NVO heat release; Mechanical Engineering; Engineering

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APA (6^th Edition):

Shingne, P. S. (2015). Thermodynamic Modeling of HCCI Combustion with Recompression and Direct Injection. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/113499

Chicago Manual of Style (16^th Edition):

Shingne, Prasad Sunand. “Thermodynamic Modeling of HCCI Combustion with Recompression and Direct Injection.” 2015. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/113499.

MLA Handbook (7^th Edition):

Shingne, Prasad Sunand. “Thermodynamic Modeling of HCCI Combustion with Recompression and Direct Injection.” 2015. Web. 10 Apr 2021.

Vancouver:

Shingne PS. Thermodynamic Modeling of HCCI Combustion with Recompression and Direct Injection. [Internet] [Doctoral dissertation]. University of Michigan; 2015. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/113499.

Council of Science Editors:

Shingne PS. Thermodynamic Modeling of HCCI Combustion with Recompression and Direct Injection. [Doctoral Dissertation]. University of Michigan; 2015. Available from: http://hdl.handle.net/2027.42/113499

University of Michigan

12. Ortiz-Soto, Elliott Alexander. Combustion Modeling of Spark Assisted Compression Ignition for Experimental Analysis and Engine System Simulations.

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

URL: http://hdl.handle.net/2027.42/102314

► Advanced combustion strategies provide significant efficiency and emissions benefits compared to conventional spark ignited (SI) combustion, but challenges related to combustion control and load limits… (more)

▼ Advanced combustion strategies provide significant efficiency and emissions benefits compared to conventional spark ignited (SI) combustion, but challenges related to combustion control and load limits have made these technologies difficult to implement in practical systems. Until now, low cost reduced order models necessary for large parametric and multi-cycle studies capable of accurately capturing the full range of combustion modes from homogeneous charge compression ignition (HCCI) and spark-assisted compression ignition (SACI) to SI have not been available. This important computational gap for advanced combustion engine research was the primary motivation for this doctoral work. The outcomes of this study include powerful new tools to evaluate advanced combustion strategies as well as novel methods to incorporate important advanced combustion characteristics into reduced order models. A reduced order thermodynamic model of advanced SACI combustion was first proposed. The model was used with available experimental data and previous high fidelity simulation results to develop a new empirical auto-ignition burn rate model that captures the effects of ignition timing, composition, temperature, pressure, engine speed, stratification and flame propagation. A complete engine model was then developed and incorporated into the commercial simulation software GT-Power. The model included chemical kinetics for low temperature heat release and auto-ignition detection and the empirical burn rate model for post-ignition heat release, as well as a new flame propagation model with improved physical groundings. The calibrated engine model showed good agreement with experimental trends of HCCI, SACI and SI combustion modes. The engine model was then used to assess practical strategies for accessing the advanced combustion regime and improving engine efficiency. The results showed HCCI and SACI provide a pathway for significant efficiency benefits compared to throttled SI, with efficiency improvements between 15-25% across a range of loads from 1-7 bar BMEP. Further efficiency gains appear possible beyond the experimentally observed SACI limit. As a further exercise, the load extension potential of boosted SACI combustion was conceptually investigated using a simple thermodynamic framework incorporating the empirical burn rate model and practical operating constraints. The results indicate boosted SACI can nearly double the maximum engine load compared to naturally aspirated operation. Advisors/Committee Members: Wooldridge, Margaret S. (committee member), Assanis, Dionissios N. (committee member), Fidkowski, Krzysztof J. (committee member), Martz, Jason Brian (committee member), Lavoie, George A. (committee member), Babajimopoulos, Aristotelis (committee member), Borgnakke, Claus (committee member).

Subjects/Keywords: Spark Assisted Compression Ignition, Saci; Homogeneous Charge Compression Ignition, Hcci, Spark Ignition, Si, Knock; Advanced Combustion Engines; Combustion Modeling; Engine Simulation; Efficiency, Fuel Economy, Load Extension, Load Expansion; Mechanical Engineering; Engineering

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APA (6^th Edition):

Ortiz-Soto, E. A. (2013). Combustion Modeling of Spark Assisted Compression Ignition for Experimental Analysis and Engine System Simulations. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/102314

Chicago Manual of Style (16^th Edition):

Ortiz-Soto, Elliott Alexander. “Combustion Modeling of Spark Assisted Compression Ignition for Experimental Analysis and Engine System Simulations.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/102314.

MLA Handbook (7^th Edition):

Ortiz-Soto, Elliott Alexander. “Combustion Modeling of Spark Assisted Compression Ignition for Experimental Analysis and Engine System Simulations.” 2013. Web. 10 Apr 2021.

Vancouver:

Ortiz-Soto EA. Combustion Modeling of Spark Assisted Compression Ignition for Experimental Analysis and Engine System Simulations. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/102314.

Council of Science Editors:

Ortiz-Soto EA. Combustion Modeling of Spark Assisted Compression Ignition for Experimental Analysis and Engine System Simulations. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/102314

13. Park, Sungjin. A Comprehensive Thermal Management System Model for Hybrid Electric Vehicles.

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

URL: http://hdl.handle.net/2027.42/84563

► This study describes the creation of efficient architecture designs of vehicle thermal man-agement system (VTMS) for hybrid electric vehicles (HEVs) by using numerical simula-tions. The… (more)

▼ This study describes the creation of efficient architecture designs of vehicle thermal man-agement system (VTMS) for hybrid electric vehicles (HEVs) by using numerical simula-tions. The objective is to develop guidelines and methodologies for the architecture de-sign of the VTMS for HEVs, which are used to improve the performance of the VTMS and the fuel economy of the vehicle. For the numerical simulations, a comprehensive model of the VTMS for HEVs which can predict the thermal response of the VTMS dur-ing transient operations is developed. The comprehensive VTMS model consists of the vehicle cooling system model and climate control system model. A vehicle powertrain model for HEVs is also developed to simulate the operating conditions of the powertrain components because the VTMS components interact with the powertrain components. Finally, the VTMS model and the vehicle powertrain model are integrated to predict thermal response of the VTMS and the fuel economy of the vehicle under various vehicle driving conditions. The comprehensive model of the VTMS for HEVs is used for the study on the architec-ture design of the VTMS for a heavy duty series hybrid electric vehicle. Integrated simu-lation is conducted using three VTMS architecture designs created based on the design guidelines developed in this study. The three architecture designs are compared based on the performance of the VTMS and the impact of the VTMS design on the fuel economy under various driving conditions. The comparison of three optional VTMS architectures shows noticeably significant differences in the parasitic power consumptions of the VTMSs and the transient temperature fluctuations of electric components depending on the architecture design. From the simulation results, it is concluded that, compared with the VTMS for the conventional vehicles, the architecture of the VTMS for the SHEV should be configured more carefully because of the additional heat source components, the complexity of component operations, and the dependency of the parasitic power con-sumption on driving modes. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Jung, Dohoy (committee member), Peng, Huei (committee member), Thompson Jr, Levi T. (committee member).

Subjects/Keywords: Thermal; Management; HEV; Modeling; Architecture Design; Mechanical Engineering; Engineering

…x29; at the University of Michigan [24]. The model is used to acquire the…

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APA (6^th Edition):

Park, S. (2011). A Comprehensive Thermal Management System Model for Hybrid Electric Vehicles. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/84563

Chicago Manual of Style (16^th Edition):

Park, Sungjin. “A Comprehensive Thermal Management System Model for Hybrid Electric Vehicles.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/84563.

MLA Handbook (7^th Edition):

Park, Sungjin. “A Comprehensive Thermal Management System Model for Hybrid Electric Vehicles.” 2011. Web. 10 Apr 2021.

Vancouver:

Park S. A Comprehensive Thermal Management System Model for Hybrid Electric Vehicles. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/84563.

Council of Science Editors:

Park S. A Comprehensive Thermal Management System Model for Hybrid Electric Vehicles. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/84563

14. Chin, Jo-Yu. Characterization of Biofuels Blends: Emissions, Permeation and Apportionment of Volatile Organic Compounds.

Degree: PhD, Environmental Health Sciences, 2011, University of Michigan

URL: http://hdl.handle.net/2027.42/86529

► The formulation of motor vehicle fuels can alter the magnitude and composition of evaporative and exhaust emissions that are associated with environmental and health impacts.… (more)

▼ The formulation of motor vehicle fuels can alter the magnitude and composition of evaporative and exhaust emissions that are associated with environmental and health impacts. The goal of this research was to investigate consequences of using the new vehicle fuels, including bioethanol and biodiesel blends. Laboratory studies were used to characterize the composition of liquid and vapors of gasoline-ethanol and diesel-biodiesel blends; assess the collinearity of fuel profiles used in receptor modeling; evaluate permeation rates and permeant compositions through personal protective equipment (PPE) materials; and measure exhaust emissions from diesel engines. In an ambient study conducted in Detroit, daily volatile organic compound (VOC) levels were measured near a major highway, and VOC sources were apportioned using positive matrix factorization, a receptor model. The compositions of biofuel blends and conventional fuels differed significantly. Predictions of vapor concentrations were highly correlated to measurements, but activity coefficients are needed for ethanol blends. Petroleum diesel and biodiesel blends, and their vapors had similar compositions, which were distinct from those of gasoline. In permeation tests, breakthrough time and permeation rate strongly depended on the fuel-PPE material combination, and permeants were enriched in benzene and other VOCs. Recommendations are made regarding PPE appropriate for the current fuels. Diesel engine exhaust emissions depended on engine calibration, load, fuel and aftertreatment systems. Biodiesel blends generally reduced emissions of particulate matter, nonmethane hydrocarbons and VOCs, however, nitrogen oxides and formaldehyde emissions increased in certain conditions. In the ambient study, VOC concentrations were generally low and varied with both seasonal and weekly patterns. The major sources were identified as gasoline exhaust, diesel exhaust, fuel evaporation, industrial emissions, biomass burning, and others. The study provides information regarding VOC profiles of the new fuels, their vapors, diesel exhaust, and ambient levels near a highway site. These profiles can be incorporated into receptor modeling. The permeation study provides guidance for selecting PPE materials. Study results can be used to assess exposure and health impacts resulting from the use of new fuels and biofuel blends. Advisors/Committee Members: Batterman, Stuart Arthur (committee member), Assanis, Dionissios N. (committee member), Robins, Thomas G. (committee member), Zellers, Edward T. (committee member).

Subjects/Keywords: CHARACTERIZATION OF BIOFUELS BLENDS; VOLATILE ORGANIC COMPOUNDS; PERMEATION; SOURCE APPORTIONMENT; Natural Resources and Environment; Science

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APA (6^th Edition):

Chin, J. (2011). Characterization of Biofuels Blends: Emissions, Permeation and Apportionment of Volatile Organic Compounds. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/86529

Chicago Manual of Style (16^th Edition):

Chin, Jo-Yu. “Characterization of Biofuels Blends: Emissions, Permeation and Apportionment of Volatile Organic Compounds.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/86529.

MLA Handbook (7^th Edition):

Chin, Jo-Yu. “Characterization of Biofuels Blends: Emissions, Permeation and Apportionment of Volatile Organic Compounds.” 2011. Web. 10 Apr 2021.

Vancouver:

Chin J. Characterization of Biofuels Blends: Emissions, Permeation and Apportionment of Volatile Organic Compounds. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/86529.

Council of Science Editors:

Chin J. Characterization of Biofuels Blends: Emissions, Permeation and Apportionment of Volatile Organic Compounds. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/86529

University of Michigan

15. Yu, Sangseok. Thermal modeling of the proton exchange membrane fuel cell.

Degree: PhD, Mechanical engineering, 2006, University of Michigan

URL: http://hdl.handle.net/2027.42/125932

► This dissertation presents a systematic approach for the study of the performance of the proton exchange membrane fuel cell (PEMFC). This work includes two simulation… (more)

▼ This dissertation presents a systematic approach for the study of the performance of the proton exchange membrane fuel cell (PEMFC). This work includes two simulation models: a comprehensive multi-dimensional thermal model and a lumped transient model of the PEMFC system. The comprehensive multi-dimensional thermal model has been developed to study the performance of the large active area unit PEMFC with a water-cooled thermal management system. The comprehensive multi-dimensional thermal model has three sub models to capture the multidisciplinary physics of the PEMFC: a water transport model in the membrane electrolyte for the electric resistance, an agglomerate structure electrochemical reaction model for the cathode overpotentials, and a two-dimensional heat transfer model for the thermal management. A sensitivity study shows that the performance of the PEMFC changes with the inlet gas stoichiometry flow rate, the inlet gas humidity and temperature, and the degree of the temperature distribution on the fuel cell. A lumped transient system model has been developed for the system level study. The model includes the transient PEMFC stack model and the transient cooling system model. A systematic approach has been suggested to boost the analysis capability via combination of two simulation models. The thermal management criteria have been determined by the unit PEMFC model. First, a proper fuel cell operating temperature was determined considering the durability and the safety margin during transient operation. Second, the temperature distribution on the fuel cell has been optimized to achieve higher performance with lower parasitic loss of the cooling pump. As a part of the systematic approach, the lumped transient system model has been used to determine the proper control algorithms to support the thermal management strategy. A feedback control algorithm has been compared to the conventional on/off control algorithm. The result shows that the feedback control algorithm is more efficient than the conventional control algorithm for the reduction of parasitic loss in the thermal management system. Moreover, the feedback control algorithm with the thermal management strategy also improves the net power of the PEMFC system. Advisors/Committee Members: Assanis, Dionissios N. (advisor), Jung, Dohoy (advisor).

Subjects/Keywords: Fuel Cells; Mass Transfer; Modeling; Proton Exchange Membrane Fuel Cell; Thermal

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APA (6^th Edition):

Yu, S. (2006). Thermal modeling of the proton exchange membrane fuel cell. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/125932

Chicago Manual of Style (16^th Edition):

Yu, Sangseok. “Thermal modeling of the proton exchange membrane fuel cell.” 2006. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/125932.

MLA Handbook (7^th Edition):

Yu, Sangseok. “Thermal modeling of the proton exchange membrane fuel cell.” 2006. Web. 10 Apr 2021.

Vancouver:

Yu S. Thermal modeling of the proton exchange membrane fuel cell. [Internet] [Doctoral dissertation]. University of Michigan; 2006. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/125932.

Council of Science Editors:

Yu S. Thermal modeling of the proton exchange membrane fuel cell. [Doctoral Dissertation]. University of Michigan; 2006. Available from: http://hdl.handle.net/2027.42/125932

16. Kwak, Kyoung Hyun. Fuel Sensitive Combustion Model Based On Quasi-Dimensional Multi-Zone Approach For Direct Injection Compression Ignition Engines.

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

URL: http://hdl.handle.net/2027.42/108990

► This study describes a development of fuel sensitive quasi-dimensional multi-zone model for a direct injection compression ignition (DICI) engine. The objective is to develop fuel… (more)

▼ This study describes a development of fuel sensitive quasi-dimensional multi-zone model for a direct injection compression ignition (DICI) engine. The objective is to develop fuel sensitive sub models of the DICI combustion process and integrate them into a thermodynamic engine cycle simulation. The proposed spray and evaporation models comprise the sub-models including fuel sensitive spray breakup, improved zone velocity estimations with transient fuel injection, spray penetration and tracking of evaporated fuel components. On these foundations, ignition delay models are formulated with two different descriptions based on the origin of the charge properties in a DICI engine. The global ignition delay model is based on the global combustion chamber charge properties while the local ignition delay model includes variations in properties of each spray zones. The Cetane number is used to describe a fuel effect for both models. Then, the premixed combustion model is reformulated to calculate a proper burn rate profile with respect to equivalence ratio and scale the profile with diluted air. While the developed models are validated and evaluated by comparing the predictions with experimental data, some of important conclusions have been made. In the spray formation model, the degree of viscosity and surface tension effect on the spray formation and air entrainment is much more pronounced with DME fuel. For the fuels closer to the conventional DF2, the effect of those properties is minimal. The evaporation model includes the behavior of evaporation at high pressure. The rate of evaporation is usually suppressed with higher pressure but at lower temperature than typical engine-like conditions, the effect is inverted. This effect might be significant for the low temperature combustion. Of the two proposed ignition delay models the local model has a slightly better accuracy compared to the global model. The results demonstrate the improvements that can be obtained when additional fuel specific properties are included in the spray ignition model. Although the proposed fuel sensitive combustion model calculates fuel effect to the combustion, the effect of ignition delay to the overall result of engine cycle simulation was much more dominant with given fuels in this study. Advisors/Committee Members: Jung, Dohoy (committee member), Borgnakke, Claus (committee member), Gamba, Mirko (committee member), Boehman, Andre L. (committee member), Assanis, Dionissios N. (committee member).

Subjects/Keywords: Diesel Engine; Quasi-dimensional Multi-zone Simulation; Alternative Fuels; Ignition Delay; Multi-component Evaporation; Spray Model; Mechanical Engineering; Engineering

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APA (6^th Edition):

Kwak, K. H. (2014). Fuel Sensitive Combustion Model Based On Quasi-Dimensional Multi-Zone Approach For Direct Injection Compression Ignition Engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/108990

Chicago Manual of Style (16^th Edition):

Kwak, Kyoung Hyun. “Fuel Sensitive Combustion Model Based On Quasi-Dimensional Multi-Zone Approach For Direct Injection Compression Ignition Engines.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/108990.

MLA Handbook (7^th Edition):

Kwak, Kyoung Hyun. “Fuel Sensitive Combustion Model Based On Quasi-Dimensional Multi-Zone Approach For Direct Injection Compression Ignition Engines.” 2014. Web. 10 Apr 2021.

Vancouver:

Kwak KH. Fuel Sensitive Combustion Model Based On Quasi-Dimensional Multi-Zone Approach For Direct Injection Compression Ignition Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/108990.

Council of Science Editors:

Kwak KH. Fuel Sensitive Combustion Model Based On Quasi-Dimensional Multi-Zone Approach For Direct Injection Compression Ignition Engines. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/108990

17. Middleton, Robert John. Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions.

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

URL: http://hdl.handle.net/2027.42/107052

► Spark Assisted Compression Ignition (SACI) combustion has been shown to provide highly efficient, potentially low NOx operation similar to Homogeneous Charge Compression Ignition (HCCI) combustion.… (more)

▼ Spark Assisted Compression Ignition (SACI) combustion has been shown to provide highly efficient, potentially low NOx operation similar to Homogeneous Charge Compression Ignition (HCCI) combustion. Direct control over ignition timing and burn rate through SACI operation has the ability to overcome shortcomings of HCCI operation allowing an increase in power density. Detailed SACI models capable of capturing the charge preparation process and impact of dilution method on combustion are currently limited. The current work addresses this need by developing such a model and investigating SACI combustion in an engine simulation. Modeling requires valid predictions of laminar flame speeds under SACI conditions which are not available in the literature. To address this need under highly EGR dilute, high preheat temperature SACI conditions, laminar reaction front simulations were conducted. Moderate burning velocities were observed for EGR dilutions typical SACI operation, provided that preheat temperatures were elevated and burned gas temperatures exceeded 1450K. For a given preheat and burned gas temperature, EGR dilution suppressed burning velocities relative to air dilution, behavior attributed to decreases in mixture oxygen. Correlations of laminar burning velocity and thickness were developed from these data. An existing model for HCCI, SI, and SACI combustion in KIVA-3V was extended to capture engine breathing and charge preparation by direct injection under conditions utilizing EGR dilution. The model was capable of predicting trend-wise agreement with metal engine cylinder pressure measurements for HCCI, SI, and SACI combustion. Analysis showed that during SACI operation, compression heating from reaction front heat release increased the end-gas temperature to initiate end-gas auto-ignition, providing control over the combustion process. Manipulation of the flame heat release by varying intake temperature, spark timing, and dilution composition allowed control over heat release rates independent of combustion phasing, reducing peak heat release rates while increasing load and efficiency. The influences on end-gas heat release rate were the total end-gas mass and the temperature stratification prior to auto-ignition, which evolved significantly during the flame propagation phase. Insights from this work can be used to guide SACI operating strategies to enable high efficiency engine operation at higher power density than with HCCI combustion. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Wooldridge, Margaret S. (committee member), Fidkowski, Krzysztof J. (committee member), Im, Hong (committee member), Martz, Jason Brian (committee member), Lavoie, George (committee member).

Subjects/Keywords: Combustion; Spark Assisted Compression Ignition; Mechanical Engineering; Engineering

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APA (6^th Edition):

Middleton, R. J. (2014). Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/107052

Chicago Manual of Style (16^th Edition):

Middleton, Robert John. “Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/107052.

MLA Handbook (7^th Edition):

Middleton, Robert John. “Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions.” 2014. Web. 10 Apr 2021.

Vancouver:

Middleton RJ. Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/107052.

Council of Science Editors:

Middleton RJ. Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/107052

18. Park, Hee Jun. Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers.

Degree: PhD, Mechanical Engineering, 2009, University of Michigan

URL: http://hdl.handle.net/2027.42/62428

► Accurate prediction of in-cylinder heat transfer is important because engine operating parameters such as in-cylinder temperature and pressure are affected by heat transfer. In-cylinder heat… (more)

▼ Accurate prediction of in-cylinder heat transfer is important because engine operating parameters such as in-cylinder temperature and pressure are affected by heat transfer. In-cylinder heat transfer modeling in multi-dimensional numerical approaches is wall-layer modeling in which a simplified one-dimensional energy equation is solved to obtain a heat flux equation. Based on the review of previous studies on in-cylinder heat transfer modeling, the most important issue is the employment of variable density effects into in-cylinder heat transfer modeling. Despite their importance, full variable density effects have not been employed in previous studies and their quantitative importance has not been investigated. Furthermore, heat transfer modeling is expected to be affected by turbulence modeling because a heat flux equation of heat transfer modeling is a function of turbulent quantities. However, the effects of turbulence modeling on predictions of thermal conditions have not been investigated. Finally, HCCI combustion processes are significantly influenced by thermal conditions and therefore, heat transfer influences HCCI combustion. However, the effects of one-dimensional heat transfer modeling on predictions of an HCCI combustion engine have not been examined. In this thesis, Variable Density Heat Transfer (VDHT) model is developed by employing the effects of density, dynamic viscosity variation and variable density effects on turbulent Prandtl number and eddy viscosity ratio variation with a power-law approximation. Through the quantification of parameter effects and comparisons of numerical results between VDHT model and the heat transfer model built in KIVA3V, details of variable density effects are discussed. The effects of turbulence modeling on predictions of thermal conditions are investigated. Heat transfer models are applied to an HCCI engine and details of heat transfer modeling effects on predictions of HCCI combustion processes are investigated. The results show that variable density effects are proportional to the difference between wall temperature and core temperature. Heat flux predictions by VDHT model are larger than those by the heat transfer model built in KIVA3V by upto 100%. Turbulence modeling strongly influences predictions of in-cylinder temperature distribution and heat flux prediction. HCCI combustion processes can be accurately predicted by VDHT model. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Jung, Dohoy (committee member), Babajimopoulos, Aristotelis (committee member), Ihme, Matthias (committee member), Lavoie, George (committee member), Wooldridge, Margaret S. (committee member).

Subjects/Keywords: Variable Density Effects Heat Transfer Modeling; Mechanical Engineering; Engineering

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APA (6^th Edition):

Park, H. J. (2009). Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/62428

Chicago Manual of Style (16^th Edition):

Park, Hee Jun. “Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers.” 2009. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/62428.

MLA Handbook (7^th Edition):

Park, Hee Jun. “Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers.” 2009. Web. 10 Apr 2021.

Vancouver:

Park HJ. Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/62428.

Council of Science Editors:

Park HJ. Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/62428

19. Lee, Chang-Ping. Turbine-Compound Free-Piston Linear Alternator Engine.

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

URL: http://hdl.handle.net/2027.42/107140

► The free-piston engine (FPE) was being used on stationary power plants and automobile test back in 1950’s. The advantages of the FPE are obtained mainly… (more)

▼ The free-piston engine (FPE) was being used on stationary power plants and automobile test back in 1950’s. The advantages of the FPE are obtained mainly from the freely moving piston, with which a variable compression ratio can be easily achieved. This gives the possibility of high compression ratio with high efficiency and the flexibility of burning different fuels. With many alternative fuels, such as biofuels under development to replace the traditional gasoline or diesel fuel, the potential of the FPE is again becoming valuable. The primary goal of the present research is to develop a numerical model of the FPE that can be used to understand the conceptual design and operation. Until now, a model for the FPE was not available, so a model is built in Matlab/Simulink with many user-defined functions and algorithms. The second goal was to integrate the FPE with a linear alternator. Historically, the FPE extracted power solely through a power turbine. Many research groups have used the linear alternator with the FPE and have claimed high efficiency. This study focused on using both power extraction devices together, namely turbine-compound free-piston linear alternator (TCFPLA) engine. It is believed that the linear alternator as the secondary power output has the potential to increase the efficiency when combined with the turbine. The most special characteristic of the TCFPLA engine is its energy-recovering configuration. With the air box fully surrounding the combustion chamber, it absorbs most of the heat from the combustion chamber. This heat recovery process was proven in the study to be a great advantage on efficiency. Two important control parameters were defined, namely the bounce chamber mass and the injection position. These two parameters have to change with load for the best performance output. A 2D engine map is generated for various linear alternator output at each given fueling rate. The brake efficiency reached 50% at the mid to high load conditions with high alternator output. This makes the TCFPLA engine very competitive with the diesel engine. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Borgnakke, Claus (committee member), Sun, Jing (committee member), Boehman, Andre L. (committee member), Durrett, Russell (committee member).

Subjects/Keywords: Free-piston; Linear Alternator; Mechanical Engineering; Engineering

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APA (6^th Edition):

Lee, C. (2014). Turbine-Compound Free-Piston Linear Alternator Engine. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/107140

Chicago Manual of Style (16^th Edition):

Lee, Chang-Ping. “Turbine-Compound Free-Piston Linear Alternator Engine.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/107140.

MLA Handbook (7^th Edition):

Lee, Chang-Ping. “Turbine-Compound Free-Piston Linear Alternator Engine.” 2014. Web. 10 Apr 2021.

Vancouver:

Lee C. Turbine-Compound Free-Piston Linear Alternator Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/107140.

Council of Science Editors:

Lee C. Turbine-Compound Free-Piston Linear Alternator Engine. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/107140

20. Northrop, William F. Particulate and Gas Phase Hydrocarbon Emissions from Partially Premixed Low Temperature Compression Ignition Combustion of Biodiesel.

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

URL: http://hdl.handle.net/2027.42/75997

► The research presented in this document examines the results of melding three diesel engine emissions reduction methodologies: partially premixed low temperature combustion (LTC); the use… (more)

▼ The research presented in this document examines the results of melding three diesel engine emissions reduction methodologies: partially premixed low temperature combustion (LTC); the use of alternative, biodiesel fuel; and aftertreatment using a diesel oxidation catalyst (DOC). It shows how alternative fuels and novel combustion strategies complement each other on one hand and create new emissions challenges on the other. Partially premixed LTC simultaneously reduces soot and NOX emissions for both biodiesel and petroleum diesel fuels. The use of biodiesel in LTC has added benefits of lowering total hydrocarbon (THC) and CO emissions and reducing soot emissions to near undetectable levels. Light hydrocarbon species like ethylene emitted from biodiesel LTC as a fraction of THC are higher independent of ignition delay indicating that biodiesel burns more completely and results in less unburned hydrocarbon (UHC) emissions than petroleum diesel. However, the generally higher gas-phase UHC emissions from LTC compared to conventional combustion results in excessive particulate matter (PM) for biodiesel due to heterogeneous condensation of methyl esters onto soot particles after dilution with atmospheric air. In the work presented here, this condensation process resulted in over an order of magnitude increase in PM emissions for B100 in a late injection LTC condition (LLTC) compared to petroleum-derived fuels. For an early injection LTC (ELTC) condition, PM emissions were almost 100 times higher than the diesel fuels tested. Low vapor pressure methyl esters making up biodiesel have a near 95% conversion from the gas to the particle phase with an undiluted exhaust UHC concentration of 1000 ppm for a 10:1 dilution ratio and 47°C collection temperature. Although the use of biodiesel in LTC increases PM emissions significantly following dilution of the raw exhaust, the results of this work indicate that 80% of UHC in the exhaust is oxidized by a standard DOC with inlet temperature of 240°C. Unfortunately, the remaining unburned biodiesel left unconverted still significantly contributes to the PM following dilution. Methyl esters were found to be the primary species contributing to the higher total organic fraction (>90%) on the PM for biodiesel compared with diesel LLTC following a DOC. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Bohac, Stani V. (committee member), Savage, Phillip E. (committee member), Sick, Volker (committee member), Szymkowicz, Patrick G. (committee member).

Subjects/Keywords: Diesel Engine Emissions; Diesel Particulate; Biodiesel; Diesel Oxidation Catalyst; Premixed Low Temperature Combustion; Mechanical Engineering; Engineering

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APA (6^th Edition):

Northrop, W. F. (2010). Particulate and Gas Phase Hydrocarbon Emissions from Partially Premixed Low Temperature Compression Ignition Combustion of Biodiesel. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/75997

Chicago Manual of Style (16^th Edition):

Northrop, William F. “Particulate and Gas Phase Hydrocarbon Emissions from Partially Premixed Low Temperature Compression Ignition Combustion of Biodiesel.” 2010. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/75997.

MLA Handbook (7^th Edition):

Northrop, William F. “Particulate and Gas Phase Hydrocarbon Emissions from Partially Premixed Low Temperature Compression Ignition Combustion of Biodiesel.” 2010. Web. 10 Apr 2021.

Vancouver:

Northrop WF. Particulate and Gas Phase Hydrocarbon Emissions from Partially Premixed Low Temperature Compression Ignition Combustion of Biodiesel. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/75997.

Council of Science Editors:

Northrop WF. Particulate and Gas Phase Hydrocarbon Emissions from Partially Premixed Low Temperature Compression Ignition Combustion of Biodiesel. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/75997

21. Abarham, Mehdi. A Combined Modeling and Experimental Investigation of Nan-Particulate Transport in Non-Isothermal Turbulent Internal Flows.

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

URL: http://hdl.handle.net/2027.42/89635

► Particles in particle-laden flows are subject to many forces including turbulent impaction, Brownian, electrostatic, thermophoretic, and gravitational. Our scaling analysis and experiments show that thermophoretic… (more)

▼ Particles in particle-laden flows are subject to many forces including turbulent impaction, Brownian, electrostatic, thermophoretic, and gravitational. Our scaling analysis and experiments show that thermophoretic force is the dominant deposition mechanism for submicron particles. One common example of industrial devices in which thermophoretic particle deposition occurs is exhaust gas recirculation (EGR) heat exchangers used on diesel engines. They are used to reduce intake charge temperature and thus reduce emissions of nitrogen oxides. The buildup of soot particles in EGR coolers causes a significant degradation in heat transfer performance (effectiveness) generally followed by the stabilization of cooler effectiveness (no more degradation) for longer exposure times. To investigate the initial sharp reduction in cooler effectiveness, an analytical solution, computational one dimensional model and an axi-symmetric model are developed to estimate particulate deposition efficiency and consequently the overall heat transfer reduction in tube flows. Internal flows (tube/channel) are employed in this dissertation to resemble real EGR coolers. The analytical solution is employed for a parametric study and sensitivity analysis to highlight the effect of critical boundary conditions. The computational models are developed to solve the governing equations for exhaust flow and particles. Model output including predicted mass deposition along the tube and the tube effectiveness drop has been compared against experiments conducted at Oak Ridge National Laboratory with good accuracy. CFD models improve the output compared to the analytical solution while the axi-symmetric model is significantly closer to the experiments due to accurate calculations of near wall fluxes. Mechanisms responsible for the cooler effectiveness stabilization in long exposure times are not clearly understood. To address the stabilization trend, a visualization test rig is developed to track the dynamics of particulate deposition and removal in-situ, and a digital microscope records any events. Interesting results are observed for flaking/removal of the deposit layer at various boundary conditions. In contrast to conventional understanding, large particles (tens of microns) were also observed in diesel exhaust. Water condensation occurring at a low EGR cooler coolant temperature resulted in a significant removal of deposit in the form of flakes while thermal expansion alone did not remove the deposit layer. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Hoard, John W. (committee member), Atreya, Arvind (committee member), Fidkowski, Krzysztof J. (committee member), Styles, Daniel J. (committee member).

Subjects/Keywords: Particle-Laden Flow; Thermophoretic Deposition; Turbulent Flow; Experimental and Computational Analysis; EGR Cooler Fouling; Mechanical Engineering; Engineering

…tech transfer office of the University of Michigan. Finally, in Chapter 6, the major…

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APA (6^th Edition):

Abarham, M. (2011). A Combined Modeling and Experimental Investigation of Nan-Particulate Transport in Non-Isothermal Turbulent Internal Flows. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/89635

Chicago Manual of Style (16^th Edition):

Abarham, Mehdi. “A Combined Modeling and Experimental Investigation of Nan-Particulate Transport in Non-Isothermal Turbulent Internal Flows.” 2011. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/89635.

MLA Handbook (7^th Edition):

Abarham, Mehdi. “A Combined Modeling and Experimental Investigation of Nan-Particulate Transport in Non-Isothermal Turbulent Internal Flows.” 2011. Web. 10 Apr 2021.

Vancouver:

Abarham M. A Combined Modeling and Experimental Investigation of Nan-Particulate Transport in Non-Isothermal Turbulent Internal Flows. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/89635.

Council of Science Editors:

Abarham M. A Combined Modeling and Experimental Investigation of Nan-Particulate Transport in Non-Isothermal Turbulent Internal Flows. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/89635

22. Salvi, Ashwin Ashok. In-situ Determination of the Thermo-physical Properties of Nano-particulate Layers Developed in Engine Exhaust Gas Heat Exchangers and Opportunities for Heat Exchanger Effectiveness Recovery.

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

URL: http://hdl.handle.net/2027.42/102356

► The use of exhaust gas recirculation (EGR) in internal combustion engines has significant impacts on engine combustion and emissions. EGR can be used to reduce… (more)

▼ The use of exhaust gas recirculation (EGR) in internal combustion engines has significant impacts on engine combustion and emissions. EGR can be used to reduce in-cylinder NOx production, reduce particulate matter, reduce fuel consumption, and enable advanced forms of combustion such as HCCI and PCI. To maximize the benefits of EGR, the exhaust gases are often cooled with liquid to gas heat exchangers. A common problem with this approach is the build-up of a fouling deposit layer inside the heat exchanger due to thermophoresis of exhaust stream particulates and condensation of volatiles. This deposit layer lowers the effectiveness of the heat exchanger at decreasing the exhaust gas temperature. The overall heat exchanger effectiveness is significantly influenced by the thermo-physical properties of the resulting deposit layer. Prior efforts have been made to quantify these properties, however measurements were performed ex-situ and in the absence of deposit volatiles. To generate more representative insights into the properties of these deposits, a novel optical measurement technique was developed to capture the native behavior of deposits in-situ. A visualization rig was designed and built to simulate an EGR cooler while providing optical and infrared access to the deposit. An in-situ methodology was developed based on 1-D conduction and measures heat flux, deposit wall temperature, deposit interface temperature, and the deposit thickness to calculate the deposit thermal conductivity at varying thicknesses and exhaust conditions. Results indicate that the novel methodology is capable of measuring and tracking deposit conductivity over a range of conditions. The measurement becomes more reliable with thicker deposit layers and at hotter interface temperatures. Deposit conductivity was shown to be independent of layer thickness, however varied with deposit surface temperature and volatile composition. Hypothesized removal mechanisms were also investigated with the visualization rig. Results show that a high pressure upstream flow transient into a quiescent chamber is capable of removing 30% of a deposit layer down to the bare substrate while significantly thinning the remaining deposit layer. Velocity based removal was more effective when combined with water condensation, producing almost 50% deposit removal. Advisors/Committee Members: Borgnakke, Claus (committee member), Hoard, John W. (committee member), Assanis, Dionissios N. (committee member), Barker, John R. (committee member), Atreya, Arvind (committee member), Styles, Daniel J. (committee member).

Subjects/Keywords: Diesel Engine Combustion and Emissions; Heat Transfer; Exhaust Gas Recirculation; EGR Heat Exchanger; Infrared Thermography; Particulate Deposit Layer; Mechanical Engineering; Transportation; Engineering; Science

…Thermogravimetric analyzer THC Total hydrocarbon ULSD Ultra low sulfur diesel UMHR University of… …Michigan Heat Release xxiii ABSTRACT The use of exhaust gas recirculation (EGR) in…

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APA (6^th Edition):

Salvi, A. A. (2013). In-situ Determination of the Thermo-physical Properties of Nano-particulate Layers Developed in Engine Exhaust Gas Heat Exchangers and Opportunities for Heat Exchanger Effectiveness Recovery. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/102356

Chicago Manual of Style (16^th Edition):

Salvi, Ashwin Ashok. “In-situ Determination of the Thermo-physical Properties of Nano-particulate Layers Developed in Engine Exhaust Gas Heat Exchangers and Opportunities for Heat Exchanger Effectiveness Recovery.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/102356.

MLA Handbook (7^th Edition):

Salvi, Ashwin Ashok. “In-situ Determination of the Thermo-physical Properties of Nano-particulate Layers Developed in Engine Exhaust Gas Heat Exchangers and Opportunities for Heat Exchanger Effectiveness Recovery.” 2013. Web. 10 Apr 2021.

Vancouver:

Salvi AA. In-situ Determination of the Thermo-physical Properties of Nano-particulate Layers Developed in Engine Exhaust Gas Heat Exchangers and Opportunities for Heat Exchanger Effectiveness Recovery. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/102356.

Council of Science Editors:

Salvi AA. In-situ Determination of the Thermo-physical Properties of Nano-particulate Layers Developed in Engine Exhaust Gas Heat Exchangers and Opportunities for Heat Exchanger Effectiveness Recovery. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/102356

23. Grannell, Shawn. The Operating Features of a Stoichiometric, Ammonia and Gasoline Dual Fueled Spark Ignition Engine.

Degree: PhD, Applied Physics, 2008, University of Michigan

URL: http://hdl.handle.net/2027.42/61689

► An overall stoichiometric mixture of air, gaseous ammonia and gasoline was metered into a single cylinder, variable compression ratio, supercharged CFR engine at varying ratios… (more)

▼ An overall stoichiometric mixture of air, gaseous ammonia and gasoline was metered into a single cylinder, variable compression ratio, supercharged CFR engine at varying ratios of gasoline to ammonia. For each combination of load, speed, and compression ratio there is a range of ratios of gasoline to ammonia for which knock-free, smooth firing was obtained. This range was investigated at its rough limit and also at its MBT knock limit. If too much ammonia is used, then the engine fires with an excessive roughness. If too much gasoline is used, then knock-free combustion can't be obtained while MBT spark timing is maintained. Stoichiometric operation on gasoline alone is also presented, for comparison. It was found that a significant fraction of the gasoline used in spark ignition engines can be replaced with ammonia. Operation on about 100% gasoline is required at idle. However, a fuel mix comprising 70% ammonia/30% gasoline on a LHV energy basis can be used at WOT. Even greater ammonia to gasoline ratios are permitted for supercharged operation. The use of ammonia with gasoline allows knock-free operation with MBT spark timing at combinations of load and compression ratio which are inaccessible to gasoline. The thermal efficiencies obtained for operation on ammonia with gasoline are as good, or better, than those obtained with gasoline alone, where comparable. The maximum brake thermal efficiency achieved during operation on ammonia with gasoline was 32.0% at 10:1 compression ratio and BMEP = 1025 kPa. The maximum brake thermal efficiency obtained during operation on gasoline alone was 24.6% at 9:1 compression ratio and BMEP = 570 kPa. Engine-out and post-catalyst emissions results are also presented. Engine-out emissions of hydrocarbons and carbon monoxide are replaced with emissions of ammonia when ammonia is used. The harmful emissions produced by an ammonia and gasoline fueled engine can be made to clean up with the same catalytic converter already in use for engines fueled by gasoline alone. The emissions clean-up window is between stoichiometric and 0.2% rich for all ratios of gasoline to ammonia. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Bohac, Stani V. (committee member), Clarke, Roy (committee member), Gillespie, Don (committee member), Orr, Bradford G. (committee member), Ross, Marc H. (committee member).

Subjects/Keywords: Ammonia Fuel Spark Ignition Engine Gasoline Efficiency Emissions; Engineering

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APA (6^th Edition):

Grannell, S. (2008). The Operating Features of a Stoichiometric, Ammonia and Gasoline Dual Fueled Spark Ignition Engine. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/61689

Chicago Manual of Style (16^th Edition):

Grannell, Shawn. “The Operating Features of a Stoichiometric, Ammonia and Gasoline Dual Fueled Spark Ignition Engine.” 2008. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/61689.

MLA Handbook (7^th Edition):

Grannell, Shawn. “The Operating Features of a Stoichiometric, Ammonia and Gasoline Dual Fueled Spark Ignition Engine.” 2008. Web. 10 Apr 2021.

Vancouver:

Grannell S. The Operating Features of a Stoichiometric, Ammonia and Gasoline Dual Fueled Spark Ignition Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/61689.

Council of Science Editors:

Grannell S. The Operating Features of a Stoichiometric, Ammonia and Gasoline Dual Fueled Spark Ignition Engine. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/61689

24. Ickes, Andrew M. Fuel Property Impact on a Premixed Diesel Combustion Mode.

Degree: PhD, Mechanical Engineering, 2009, University of Michigan

URL: http://hdl.handle.net/2027.42/62369

► New premixed diesel combustion strategies, with their low engine-out PM and NOx emissions, are highly attractive for production implementation given increasingly strict emissions regulations. Accordingly,… (more)

▼ New premixed diesel combustion strategies, with their low engine-out PM and NOx emissions, are highly attractive for production implementation given increasingly strict emissions regulations. Accordingly, premixed diesel combustion strategies must operate effectively on commercially available diesel fuel, whose critical properties vary substantially. It is therefore critical to understand how premixed diesel combustion strategies respond to variations in fuel properties, especially cetane number the primary quantification of ignition behavior. This research study sought to understand the connection between diesel fuel properties, in particular cetane number, and the combustion and emissions behavior of premixed diesel combustion. Four primary test fuels with cetane numbers varying over the range expected in the field (42-53) were used, along with a secondary matrix of fuels to characterize the behavior of a nitrate cetane improver. Fuel effects were quantified across a range of EGR levels, injection pressures, and engine loads to identify secondary parameter interactions. Gaseous emissions, particularly NOx emissions, were found to be dependent solely on combustion phasing and EGR rate for the primary test fuels at the studied condition. Fuel cetane number shifts the combustion phasing (increasing cetane number advances phasing) but is only one of many different parameters which shift combustion. The effect of varying cetane number can be counteracted by varying injection timing to yield matched combustion phasing. The presence of 2-ethylhexyl nitrate (2-EHN) cetane improver within the fuel introduces a new fuel-borne NOx formation mechanism to the combustion process, which significantly increases NOx emissions in a premixed diesel combustion mode. The increase in NOx emissions stems from NOx formed by the decomposition of the 2-EHN additive. The trends and magnitudes of soot, CO, and HC emissions remain constant for all tested fuels across a range of engine loads. The high load limit of the tested premixed diesel combustion mode is primarily limited by equivalence ratio, with excessive soot, CO, and HC emissions resulting as the overall equivalence ratio approaches stoichiometric. The light load limit is limited by high CO and HC emissions and the ability of a diesel oxidation catalyst to reduce these emissions to acceptable levels. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Bohac, Stani V. (committee member), Driscoll, James F. (committee member), Sick, Volker (committee member), Szymkowicz, Patrick G. (committee member).

Subjects/Keywords: Premixed Diesel Combustion; Diesel Fuel; Mechanical Engineering; Engineering

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APA (6^th Edition):

Ickes, A. M. (2009). Fuel Property Impact on a Premixed Diesel Combustion Mode. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/62369

Chicago Manual of Style (16^th Edition):

Ickes, Andrew M. “Fuel Property Impact on a Premixed Diesel Combustion Mode.” 2009. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/62369.

MLA Handbook (7^th Edition):

Ickes, Andrew M. “Fuel Property Impact on a Premixed Diesel Combustion Mode.” 2009. Web. 10 Apr 2021.

Vancouver:

Ickes AM. Fuel Property Impact on a Premixed Diesel Combustion Mode. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/62369.

Council of Science Editors:

Ickes AM. Fuel Property Impact on a Premixed Diesel Combustion Mode. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/62369

25. 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

26. Mamalis, Sotirios. Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines.

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

URL: http://hdl.handle.net/2027.42/96073

► High Pressure Lean Burn (HPLB) engines have the potential to achieve high load with high efficiency and low emissions compared to currently available powertrains. Various… (more)

▼ High Pressure Lean Burn (HPLB) engines have the potential to achieve high load with high efficiency and low emissions compared to currently available powertrains. Various HPLB concepts have been experimentally studied in the literature, focusing on the combustion event but often neglecting the techniques required to provide appropriate cylinder boundary conditions. This dissertation investigates the interactions between the combustion event, in this case Homogeneous Charge Compression Ignition (HCCI), and engine processes occurring externally to the cylinder that are critical for HPLB operation. For that reason, multi-cylinder boosted HCCI engines were simulated and analyzed based on energy and exergy flow considerations. The multi-cylinder engine model included several submodels the most critical of which were the HCCI combustion and heat transfer modules. Both of these were evaluated based on different experimental datasets and their capability to simulate wide range operation was assessed. The calibrated models were subsequently used to explore the synergies between boosting, Variable Valve Actuation (VVA), Exhaust Gas Recirculation (EGR) and different compression ratio levels for high load HCCI. It was found that utilizing hot intake air is highly beneficial for boosted operation. Hot air can reduce dependence on residual gas for mixture composition and temperature control; it also allows manipulation of the valve strategy so that boosting performance is optimized. In fact, it enables use of regular high lift valve events for improving engine efficiency and suppressing pressure rise rates. It was found that the combination of advanced boosting systems with VVA strategies offers significant efficiency benefits and renders HCCI technology more accessible for future powertrain applications. Energy and exergy analysis showed that advanced boosting and VVA enhanced dilution levels, suppressed cylinder temperatures and lowered pumping work. The outcome was high levels of thermal and gas exchange efficiencies. These benefits were enough to outweigh drawbacks from increased cylinder irreversibilities and reduced exhaust flow exergy, both resulting from low temperature combustion. Low heat rejection was also explored and was found to be very beneficial for HCCI. Overall, the engine simulation and analysis framework provides a useful tool for exploration and assessment of HPLB engines employing current or future technology. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Borgnakke, Claus (committee member), Ihme, Matthias (committee member), Babajimopoulos, Aristotelis (committee member), Lavoie, George (committee member), Sick, Volker (committee member).

Subjects/Keywords: Simulation and Thermodynamic Analysis; High Pressure Lean Burn Engines; Mechanical Engineering; Engineering

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APA (6^th Edition):

Mamalis, S. (2012). Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/96073

Chicago Manual of Style (16^th Edition):

Mamalis, Sotirios. “Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines.” 2012. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/96073.

MLA Handbook (7^th Edition):

Mamalis, Sotirios. “Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines.” 2012. Web. 10 Apr 2021.

Vancouver:

Mamalis S. Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2012. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/96073.

Council of Science Editors:

Mamalis S. Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines. [Doctoral Dissertation]. University of Michigan; 2012. Available from: http://hdl.handle.net/2027.42/96073

27. Janakiraman, Vijay Manikandan. Machine Learning for Identification and Optimal Control of Advanced Automotive Engines.

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

URL: http://hdl.handle.net/2027.42/102392

► The complexity of automotive engines continues to increase to meet increasing performance requirements such as high fuel economy and low emissions. The increased sensing capabilities… (more)

Subjects/Keywords: Machine Learning; HCCI Engine Identification; Nonlinear Identification; Support Vector Machines; Online Learning Algorithms for Extreme Learning Machines; Electrical Engineering; Mechanical Engineering; Engineering

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APA (6^th Edition):

Janakiraman, V. M. (2013). Machine Learning for Identification and Optimal Control of Advanced Automotive Engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/102392

Chicago Manual of Style (16^th Edition):

Janakiraman, Vijay Manikandan. “Machine Learning for Identification and Optimal Control of Advanced Automotive Engines.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/102392.

MLA Handbook (7^th Edition):

Janakiraman, Vijay Manikandan. “Machine Learning for Identification and Optimal Control of Advanced Automotive Engines.” 2013. Web. 10 Apr 2021.

Vancouver:

Janakiraman VM. Machine Learning for Identification and Optimal Control of Advanced Automotive Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/102392.

Council of Science Editors:

Janakiraman VM. Machine Learning for Identification and Optimal Control of Advanced Automotive Engines. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/102392

University of Michigan

28. Han, Manbae. Species resolved hydrocarbon emission profiles from advanced diesel combustion and characterization of heat-up diesel oxidation catalysts.

Degree: PhD, Pure Sciences, 2007, University of Michigan

URL: http://hdl.handle.net/2027.42/126433

► This study summarizes the successful characterization of a heat-up diesel oxidation catalyst (DOC) combined with a low-temperature premixed charge compression ignition (PCI) combustion to further… (more)

▼ This study summarizes the successful characterization of a heat-up diesel oxidation catalyst (DOC) combined with a low-temperature premixed charge compression ignition (PCI) combustion to further reduce exhaust emissions. Because different types of hydrocarbon (HC) species can affect DOC oxidation performance, a direct raw exhaust HC sampling and speciation method with gas chromatography (GC), capable of identifying 70% HC carbon mass, was developed to minimize condensation on particulate matter (PM) of mid or high boiling temperature HC species during exhaust sampling. This HC speciation method provided species resolved HC emission profiles from combustion modes (lean conventional, lean PCI, rich PCI) and engine parameters (injection timing, exhaust gas recirculation (EGR) rate, speed, and load). Highly increased soot precursor concentration as combustion mode changes from lean conventional to lean PCI to rich PCI, reflects a limiting of the soot-forming reactions from the decreased combustion temperature and better fuel-air mixing. As injection timing is retarded and EGR rate is increased in the PCI regime, a higher yield of HC emission was observed mainly due to lower bulk gas temperature. The lower temperature causes increase of HC emission, relative partially burned HCs and relative alkenes+alkynes concentration. Speed and load effect on HC species emission showed more complicated HC emission trends than injection timing and EGR rate because all of the engine control parameters were optimized to compromise fuel economy and emissions. Two representative HC species in typical diesel exhaust are ethene and n-undecane, which are used for reactor tests. Through evaluation of three DOC formulations e.g., platinum (Pt) only, Pt and palladium (Pd), and Pt and Pd with ceria (CeO₂), by a reactor test, the PtPd catalyst shows the lowest light-off temperature, followed by the PtPd+CeO₂ catalyst and then the Pt catalyst, regardless of combustion modes, HC species compositions, and oxygen concentrations. Although in-situ engine test of the PtPd catalyst with post in-cylinder fuel injection shows that PCI is superior to conventional combustion in increasing exhaust gas temperature, PCI produces significant PM as post fuel injection timing is retarded. An extra fuel injection system immediately before the DOC would most likely solve this problem. Advisors/Committee Members: Assanis, Dionissios N. (advisor), Bohac, Stani V. (advisor).

Subjects/Keywords: Advanced; Catalysts; Characterization; Combustion; Diesel; Emission; Heat-up; Hydrocarbon; Oxidation; Profiles; Resolved; Species

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APA (6^th Edition):

Han, M. (2007). Species resolved hydrocarbon emission profiles from advanced diesel combustion and characterization of heat-up diesel oxidation catalysts. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/126433

Chicago Manual of Style (16^th Edition):

Han, Manbae. “Species resolved hydrocarbon emission profiles from advanced diesel combustion and characterization of heat-up diesel oxidation catalysts.” 2007. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/126433.

MLA Handbook (7^th Edition):

Han, Manbae. “Species resolved hydrocarbon emission profiles from advanced diesel combustion and characterization of heat-up diesel oxidation catalysts.” 2007. Web. 10 Apr 2021.

Vancouver:

Han M. Species resolved hydrocarbon emission profiles from advanced diesel combustion and characterization of heat-up diesel oxidation catalysts. [Internet] [Doctoral dissertation]. University of Michigan; 2007. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/126433.

Council of Science Editors:

Han M. Species resolved hydrocarbon emission profiles from advanced diesel combustion and characterization of heat-up diesel oxidation catalysts. [Doctoral Dissertation]. University of Michigan; 2007. Available from: http://hdl.handle.net/2027.42/126433

University of Michigan

29. Wu, Bin. Using high-fidelity simulations and artificial neural networks in calibration and control of high -degree -of -freedom internal combustion engines.

Degree: PhD, Mechanical engineering, 2006, University of Michigan

URL: http://hdl.handle.net/2027.42/125779

► Internal combustion engines experience a wide range of operating conditions, thus requiring design compromises to achieve satisfactory overall performance. However, there is strong motivation to… (more)

▼ Internal combustion engines experience a wide range of operating conditions, thus requiring design compromises to achieve satisfactory overall performance. However, there is strong motivation to make fixed parameters variable, permitting design constraints to be relaxed. This increases the system complexity due to increased degrees of freedom and complicated interactions among these independent control variables. Developing controllers and calibration maps becomes increasingly challenging, as the total number of experiments required for calibration increases exponentially with the number of independent control variables. Hence, the traditional calibration methodology, which generates look-up tables through systematic sweep tests, becomes prohibitively expensive. This study answers the challenge imposed by high degrees of freedom through development of a simulation-based algorithm. A high-fidelity engine simulation tool is developed to predict engine performance corresponding to different control variable combinations. Pre-optimality studies are conducted to generate high-fidelity simulation benchmarks. Since optimization is very computation-intensive, it is not feasible to use the high-fidelity tool for solving optimization problems directly. Instead, Artificial Neural Networks (ANN) trained with high-fidelity simulation results are used as surrogate models. The ANNs are shown to be capable of representing complex relationships between multiple independent variables and selected engine performance indicators, such as brake torque, fuel consumption, NOx emissions, etc. Finally, the ANN surrogate models are employed in the optimization framework that searches the optimal combination of setpoints for any given driving condition. The proposed algorithm is demonstrated on a conventional port-injected Spark-Ignition (SI) engine with two additional degrees of freedom introduced by the dual independent Variable Valve Timing (VVT) mechanism. The intake and exhaust camshaft positions are optimized for both wide open throttle and part load, using the appropriate combinations of optimization objectives and constraints. In addition, the capability of generating fast ANN models is utilized for developing a real-time air mass flow rate estimator for a VVT engine. With proper adaptation, the algorithm can be extended for complex engine and powertrain systems with even more degrees of freedom. Advisors/Committee Members: Assanis, Dionissios N. (advisor), Filipi, Zoran S. (advisor).

Subjects/Keywords: Artificial Neural Networks; Calibration; Control; Fidelity; High-degree-of-freedom; Internal Combustion Engines; Simulations; Using

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APA (6^th Edition):

Wu, B. (2006). Using high-fidelity simulations and artificial neural networks in calibration and control of high -degree -of -freedom internal combustion engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/125779

Chicago Manual of Style (16^th Edition):

Wu, Bin. “Using high-fidelity simulations and artificial neural networks in calibration and control of high -degree -of -freedom internal combustion engines.” 2006. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/125779.

MLA Handbook (7^th Edition):

Wu, Bin. “Using high-fidelity simulations and artificial neural networks in calibration and control of high -degree -of -freedom internal combustion engines.” 2006. Web. 10 Apr 2021.

Vancouver:

Wu B. Using high-fidelity simulations and artificial neural networks in calibration and control of high -degree -of -freedom internal combustion engines. [Internet] [Doctoral dissertation]. University of Michigan; 2006. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/125779.

Council of Science Editors:

Wu B. Using high-fidelity simulations and artificial neural networks in calibration and control of high -degree -of -freedom internal combustion engines. [Doctoral Dissertation]. University of Michigan; 2006. Available from: http://hdl.handle.net/2027.42/125779

30. Olesky, Laura Katherine. An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap.

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

URL: http://hdl.handle.net/2027.42/99979

► The implementation of homogeneous charge compression ignition (HCCI) in an engine remains a challenge due to the limited operating range and lack of a direct… (more)

▼ The implementation of homogeneous charge compression ignition (HCCI) in an engine remains a challenge due to the limited operating range and lack of a direct ignition timing control mechanism. Spark assisted compression ignition (SACI) has been shown by several research groups, including the work presented here, to provide such a mechanism, helping to control the phasing and stability of a primarily auto-igniting charge, as well as provide a means of extending the high load limit of HCCI while maintaining high thermal efficiency. The approach used in this study is unique in that flexible engine valve timing allowed for independent control of the thermal/compositional stratification associated with a large internal residual fraction, allowing its effect to be isolated from other thermophysical parameters. In these experiments, a single-cylinder engine equipped with fully-flexible valve actuation was used to explore the effects of spark assist in controlling peak heat release rates. With spark assist, a small portion of the heat release occurred via flame propagation, increasing the overall duration of the combustion event and dramatically reducing peak rates of heat release. At constant engine load and combustion phasing, peak heat release rates were reduced by 40% by controlling spark timing and unburned gas temperature via changes in internal and external EGR rates. Internal EGR was adjusted by varying the duration of negative valve overlap (NVO); for the range of NVO investigated, potential variations in in-cylinder mixing and thermal/compositional stratification were found to have a weak effect on burn characteristics, confirming the notion that temperature and spark timing are the primary variables affecting SACI burn rates for a fixed mixture composition. In the experiments, heat release analysis showed that the behavior of SACI was consistent with the theoretical kinetics associated with turbulent flame propagation and auto-ignition, supporting the hypothesis that SACI is essentially two distinct energy release events coupled by compression heating from an expanding flame front. The results of this work provide new insights into the physical and chemical mechanisms important during low temperature combustion. The results confirm proposed representations of SACI, and thereby provide direction for developing new advanced low temperature engine strategies. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Wooldridge, Margaret S. (committee member), Driscoll, James F. (committee member), Boehman, Andre L. (committee member), Lavoie, George A. (committee member), Martz, Jason Brian (committee member).

Subjects/Keywords: Spark Assisted Compression Ignition Combustion; Low Temperature Combustion; Mechanical Engineering; Engineering

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APA (6^th Edition):

Olesky, L. K. (2013). An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/99979

Chicago Manual of Style (16^th Edition):

Olesky, Laura Katherine. “An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 10, 2021. http://hdl.handle.net/2027.42/99979.

MLA Handbook (7^th Edition):

Olesky, Laura Katherine. “An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap.” 2013. Web. 10 Apr 2021.

Vancouver:

Olesky LK. An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 10]. Available from: http://hdl.handle.net/2027.42/99979.

Council of Science Editors:

Olesky LK. An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/99979

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