+publisher:"University of Michigan" +contributor:("Borgnakke, Claus")

University of Michigan

1. Kumar Aanjaneya, . Facilitation of Homogeneous Combustion with Oxygen Enrichment for High-Temperature Industrial Furnaces.

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

URL: http://hdl.handle.net/2027.42/155272

► A substantial portion of literature discussing highly efficient and low pollutant emission combustion systems comprises of Homogeneous Combustion (HC) or its variants (MILD, FLOX, CDC… (more)

▼ A substantial portion of literature discussing highly efficient and low pollutant emission combustion systems comprises of Homogeneous Combustion (HC) or its variants (MILD, FLOX, CDC etc.). The underlying theory among the aforementioned methods is the reduction of the Damköhler number (Da) to the order of unity. To attain high temperatures, industrial heating is often accomplished by using “enriched” oxidizer streams i.e. XO2 > 21%. Extending the concept of HC to applications of industrial heating (e.g. glass melting furnaces) is a desirable but a challenging task. Higher reactant concentrations increase reaction rates. Fast reactions lead to an increase in temperature which in-turn accelerates the reaction rates and the heat release rate. This self-accelerating cycle causes a shift to the conventional mode of combustion (higher Da) with high NOx emissions. The broad research goal in this work is to keep Da ~ 1 to facilitate HC with enriched oxidizers. The first strategy employed towards this was to enhance the heat removal from the reaction zone by enabling the presence of soot in the reaction zone. The conjecture was that presence of soot will augment heat radiation, reduce temperatures, and reduce NOx emissions; similar to what has been reported for highly luminous flames. Since natural gas (methane) does not soot except under high pressure environments, fuel blends containing small amounts of lightly sooting fuels like ethylene were investigated. It was found that while the presence of soot definitely improves radiation heat transfer and reduces specific NOx emissions, there is an optimal blend level. A multi-variate regression model was used to demarcate the radiation emanating from the wall and from the gaseous zone. The second strategy employed was to engineer the flow in the furnace to enhance mixing and reduce Da. Experimentally studying the confined turbulent jet(s) flow in the furnace with limited optical access was infeasible and hence computational simulations were utilized. A number of steps to reduce computational expenses were taken. These included utilization of furnace symmetry and writing external code to describe furnace recuperator operation. The 3-D flow within the furnace was described/understood by breaking it into a set of canonical flows. The utilization of a detailed mechanism (GRI Mech-3.0) enabled accurate capture of the NOx field to within a few ppm. It was discovered that optimizing geometry and flow is important to achieve HC with enriched oxidizers. The third strategy focused on further enhancing jet dilution by modifying nozzle design. It was found that altering the nozzle shape caused essentially no reduction in NOx emissions from the furnace. It was also found that NOx emissions were independent of the inlet temperature of the reactants. Another strategy was to have a localized swirling injection for the oxidizer jet. While swirl did help in reducing NOx, there existed an optimal swirl number beyond which NOx emissions were aggravated to levels even higher than configurations… Advisors/Committee Members: Atreya, Arvind (committee member), Borgnakke, Claus (committee member), Raman, Venkatramanan (committee member), Wooldridge, Margaret S (committee member).

Subjects/Keywords: Homogeneous Combustion; NOx; Industrial Furnace; Oxygen Enriched; Mechanical Engineering; Engineering

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APA (6^th Edition):

Kumar Aanjaneya, .. (2020). Facilitation of Homogeneous Combustion with Oxygen Enrichment for High-Temperature Industrial Furnaces. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/155272

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Chicago Manual of Style (16^th Edition):

Kumar Aanjaneya, .. “Facilitation of Homogeneous Combustion with Oxygen Enrichment for High-Temperature Industrial Furnaces.” 2020. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/155272.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

Kumar Aanjaneya, .. “Facilitation of Homogeneous Combustion with Oxygen Enrichment for High-Temperature Industrial Furnaces.” 2020. Web. 07 Mar 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

Kumar Aanjaneya, .. Facilitation of Homogeneous Combustion with Oxygen Enrichment for High-Temperature Industrial Furnaces. [Internet] [Doctoral dissertation]. University of Michigan; 2020. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/155272.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

Kumar Aanjaneya, .. Facilitation of Homogeneous Combustion with Oxygen Enrichment for High-Temperature Industrial Furnaces. [Doctoral Dissertation]. University of Michigan; 2020. Available from: http://hdl.handle.net/2027.42/155272

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

2. Mansfield, Andrew Benjamin. Experimental Study of Synthesis Gas Combustion Chemistry and Ignition Behaviors.

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

URL: http://hdl.handle.net/2027.42/110478

► The development of synthesis gas (syngas) fuel is of interest, as it can enable a transition from fossil to renewable energy sources while reducing the… (more)

▼ The development of synthesis gas (syngas) fuel is of interest, as it can enable a transition from fossil to renewable energy sources while reducing the emissions associated with both. Historical research has focused on basic syngas formulations (H2 & CO) in homogeneous environments, providing a baseline for consideration of more realistic mixtures and devices. Recent research and industrial experience for syngas fueled combustors indicate the effects of common disturbances can be dramatic and are not well-understood, with particular concern regarding the occurrence of uncontrolled inhomogeneous auto-ignition and its effect on the accuracy of common homogeneous reactor modeling. This dissertation represents an experimental investigation of syngas combustion, aimed at comprehensively understanding the effects of specific chemical and physical disturbances at high-pressure low-temperature conditions. Experiments were conducted in the University of Michigan-Rapid Compression Facility. The auto-ignition behaviors of syngas were investigated, revealing the existence of both homogeneous and inhomogeneous characteristics depending strongly on the initial unburned thermodynamic state. The behaviors were mapped over a wide range of conditions revealing consistent patterns. It was discovered that the Sankaran Criterion, a previously proposed relationship between chemical kinetics, transport properties, and known thermal disturbances, could predict the location of inhomogeneous behavior on these maps with remarkable accuracy. This provides evidence that commonly ignored thermal disturbances can cause uncontrolled inhomogeneous auto-ignition in syngas and also provides a straightforward method to predict such behavior. As expected, inhomogeneous auto-ignition behavior was well correlated to error in homogeneous reactor modeling for higher energy content mixtures. The effects of chemical impurities on the combustion of syngas were investigated, focusing on CH4, a common component of syngas, and trimethylsilanol (TMS), an unstudied impurity related to those common to landfill-based syngas. The impact of CH4 was to inhibit ignition, evidenced by auto-ignition delay time increases by up to a factor of 3. Conversely the impact of TMS was to promote ignition, causing drastic reductions in auto-ignition delay time up to 70%. These large promotion effects have significant safety implications, as pronounced early auto-ignition can lead to catastrophic failures and concentrations of similar Si containing species are expected to increase in the future. Advisors/Committee Members: Wooldridge, Margaret S. (committee member), Driscoll, James F. (committee member), Borgnakke, Claus (committee member), Im, Hong G. (committee member).

Subjects/Keywords: Syngas; Iso-octane; Rapid compression facility; Strong and weak ignition; Impurity; Trimethylsilanol; Mechanical Engineering; Engineering

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APA (6^th Edition):

Mansfield, A. B. (2014). Experimental Study of Synthesis Gas Combustion Chemistry and Ignition Behaviors. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/110478

Chicago Manual of Style (16^th Edition):

Mansfield, Andrew Benjamin. “Experimental Study of Synthesis Gas Combustion Chemistry and Ignition Behaviors.” 2014. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/110478.

MLA Handbook (7^th Edition):

Mansfield, Andrew Benjamin. “Experimental Study of Synthesis Gas Combustion Chemistry and Ignition Behaviors.” 2014. Web. 07 Mar 2021.

Vancouver:

Mansfield AB. Experimental Study of Synthesis Gas Combustion Chemistry and Ignition Behaviors. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/110478.

Council of Science Editors:

Mansfield AB. Experimental Study of Synthesis Gas Combustion Chemistry and Ignition Behaviors. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/110478

University of Michigan

3. Younkins, Matthew A. Improving the Efficiency of the Hydrogen Engine.

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

URL: http://hdl.handle.net/2027.42/96162

► Internal combustion engines fueled by hydrogen are among the most efficient means of converting chemical energy to mechanical work. The exhaust has near-zero carbon emissions… (more)

▼ Internal combustion engines fueled by hydrogen are among the most efficient means of converting chemical energy to mechanical work. The exhaust has near-zero carbon emissions and fuel efficiency exceeding fuel cells is achievable. Unfortunately, the fuel costs are high and efficient combustion of hydrogen in engines produces nitrogen oxides (NOx) that cannot be treated with conventional three-way catalysts. This work presents the results of experiments which consider changes in hydrogen engine design and/or operating strategy to improve engine performance, consisting primarily of engine efficiency and NOx emissions. Various combustion chamber designs, compression ratios, operating parameters, and injector nozzles were tested, and the relative gains found ranged from 0 to 5%. Three research areas were considered in greater detail to reduce NOx emissions and improve hydrogen engine efficiencies. The first effort focused on injecting liquid water into a cylinder filled with a premixed fuel-air charge. The results were compared against expectations for a conventionally operated hydrogen engine. Using this approach of direct injection of water into the cylinder, NOx emissions were reduced by up to 95%. At a threshold of 100 ppm of NOx, peak load possible increased by 17.3%. The second research area considered injecting water into the intake air charge. With water injection into the intake air charge, the NOx emissions were reduced by 87%. At a threshold of 90 ppm of NOx, peak load possible increased by 23.9%. Finally, experimental data were generated and analyzed for a combustion chamber with two spark plugs. An injector was designed to preferentially stratify the fuel towards the ignition sites. Results from a metal engine and an optically accessible engine are presented. Based on the metal engine data, the new cylinder head design produced a remarkable 47.7% net indicated thermal efficiency (ITE) while producing only 51 ppm of NOx. Laser induced fluorescence was used in the optically accessible engine to visualize the fuel distribution during non-firing operation. The most optimal injection conditions (based on the metal engine results) showed a fuel distribution where the equivalence ratio is approximately 0.65 near the ignition locations. Advisors/Committee Members: Wooldridge, Margaret S. (committee member), Kolmanovsky, Ilya Vladimir (committee member), Im, Hong (committee member), Borgnakke, Claus (committee member).

Subjects/Keywords: Hydrogen Engine; Water Injection; Mechanical Engineering; Engineering

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APA (6^th Edition):

Younkins, M. A. (2012). Improving the Efficiency of the Hydrogen Engine. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/96162

Chicago Manual of Style (16^th Edition):

Younkins, Matthew A. “Improving the Efficiency of the Hydrogen Engine.” 2012. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/96162.

MLA Handbook (7^th Edition):

Younkins, Matthew A. “Improving the Efficiency of the Hydrogen Engine.” 2012. Web. 07 Mar 2021.

Vancouver:

Younkins MA. Improving the Efficiency of the Hydrogen Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2012. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/96162.

Council of Science Editors:

Younkins MA. Improving the Efficiency of the Hydrogen Engine. [Doctoral Dissertation]. University of Michigan; 2012. Available from: http://hdl.handle.net/2027.42/96162

University of Michigan

4. 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 March 07, 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. 07 Mar 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 Mar 07]. 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

5. 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 March 07, 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. 07 Mar 2021.

Vancouver:

Shingne PS. Thermodynamic Modeling of HCCI Combustion with Recompression and Direct Injection. [Internet] [Doctoral dissertation]. University of Michigan; 2015. [cited 2021 Mar 07]. 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

6. 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 March 07, 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. 07 Mar 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 Mar 07]. 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

University of Michigan

7. Xiao, Yun. Stochastic combustion modeling of direct injection diesel engines.

Degree: PhD, Mechanical engineering, 1991, University of Michigan

URL: http://hdl.handle.net/2027.42/128726

► A comprehensive diesel engine combustion model has been developed. The model is an extension of similar thermodynamic multi-zone models for gasoline engines. In diesel engines… (more)

▼ A comprehensive diesel engine combustion model has been developed. The model is an extension of similar thermodynamic multi-zone models for gasoline engines. In diesel engines a charge of air and residuals is present into which fuel is injected creating a highly inhomogeneous mixture and multi-phase spray structure. The non-uniformity on both local and global scales makes the diesel engine environment very difficult to characterize. In this model, the charge is divided into many distinct zones to express geometric information and to provide spatial resolution. Within each zone structure, mass, momentum and energy conservations are expressed as lumped formulations. This basic structure is coupled with a stochastic treatment of the properties and processes related to turbulent mixing and transport. This description plays an essential part in the modeling of the inhomogeneity and the turbulent mixing. Besides the overall model development, the thesis improves the models for combustion product equilibrium composition and properties with an increased range of validity, which is crucial for diesel combustion simulations because of the wide local fuel-air ratio range. It also gives a robust solution procedure. A new coalescence/dispersion model for stochastic turbulent mixings is proposed. The new model provides a more realistic description of the initial phase of mixing which strongly affects burn rate predictions. Compressibility effects on turbulence are studied and significant improvements are made over the previous engine flow models. It is demonstrated that Reynolds stress models are needed to predict the non-equilibrium and anisotropic in-cylinder flows as they are subject to unsteady and nonisotropic compressions. The overall model is demonstrated to correlate well with experiments with respect to performance. Pressure trace and heat release are shown as functions of major operating conditions: inlet pressure and temperature, fuel-air ratio, EGR, fuel injection conditions, turbulence and swirl levels. NO\sb x and soot emissions are predicted as functions of load, EGR, injection timing and turbulence level. No comparison with experiments is made for emission predictions. Advisors/Committee Members: Borgnakke, Claus (advisor).

Subjects/Keywords: Combustion; Diesel; Direct; Engines; Injection; Modeling; Stochastic

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APA (6^th Edition):

Xiao, Y. (1991). Stochastic combustion modeling of direct injection diesel engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/128726

Chicago Manual of Style (16^th Edition):

Xiao, Yun. “Stochastic combustion modeling of direct injection diesel engines.” 1991. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/128726.

MLA Handbook (7^th Edition):

Xiao, Yun. “Stochastic combustion modeling of direct injection diesel engines.” 1991. Web. 07 Mar 2021.

Vancouver:

Xiao Y. Stochastic combustion modeling of direct injection diesel engines. [Internet] [Doctoral dissertation]. University of Michigan; 1991. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/128726.

Council of Science Editors:

Xiao Y. Stochastic combustion modeling of direct injection diesel engines. [Doctoral Dissertation]. University of Michigan; 1991. Available from: http://hdl.handle.net/2027.42/128726

8. Lee, Insu. An Experimental and Numerical Study of Confined Non-reacting and Reacting Turbulent Jets to Facilitate Homogeneous Combustion in Industrial Furnaces.

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

URL: http://hdl.handle.net/2027.42/111503

► Confined non-reacting turbulent jets are ideal for recirculating the hot flue gas back into the furnace from an external exhaust duct. Such jets are also… (more)

▼ Confined non-reacting turbulent jets are ideal for recirculating the hot flue gas back into the furnace from an external exhaust duct. Such jets are also used inside the furnace to internally entrain and recirculate the hot flue gas to preheat and dilute the reactants. Both internal and external implementation of confined turbulent jets increase the furnace thermal efficiency. For external implementation, depending on the circumstances, the exhaust gas flow may be co- or counter-flow relative to the jet flow. Inside the furnaces, fuel and air jets are injected separately. To create a condition which can facilitate near homogeneous combustion, these jets have to first mix with the burned gas inside the furnace and simultaneously being heated and diluted prior to combustion. Clearly, the combustion pattern and emissions from reacting confined turbulent jets are affected by jet interactions, mixing and entrainment of hot flue gas. In this work, the flow and mixing characteristics of a non-reacting and reacting confined turbulent jet are investigated experimentally and numerically. This work consists of two parts: (i) A study of flow and mixing characteristics of non-reacting confined turbulent jets with co- or counter-flowing exhaust/flue gas. Here the axial and radial distributions of temperature, velocity and NO concentration (used as a tracer gas) were measured. FLUENT was used to numerically simulate the experimental results. This work provides the basic understanding of the flow and mixing characteristics of confined turbulent jets and develops some design considerations for recirculating flue gas back into the furnace as expressed by the recirculation zone and the stagnation locations. (ii) Numerical calculations of near homogeneous combustion are performed for the existing furnace. The exact geometry of the furnace in the lab is used and the real dimensional boundary conditions are considered. The parameters such as air nozzle diameter (dair), fuel nozzle diameter (df), equivalence ratio (Φ), oxygen concentration, gravity, different bottom temperature and separation distance as well as soot radiation that influence the establishment of homogeneous combustion to improve combustion efficiency and reduce pollutant emissions will be numerically studied. Advisors/Committee Members: Atreya, Arvind (committee member), Borgnakke, Claus (committee member), Driscoll, James F. (committee member), Wooldridge, Margaret S. (committee member).

Subjects/Keywords: non-reacting and reacting confined turbulent jet; homogeneous combustion; Mechanical Engineering; Engineering

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APA (6^th Edition):

Lee, I. (2015). An Experimental and Numerical Study of Confined Non-reacting and Reacting Turbulent Jets to Facilitate Homogeneous Combustion in Industrial Furnaces. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/111503

Chicago Manual of Style (16^th Edition):

Lee, Insu. “An Experimental and Numerical Study of Confined Non-reacting and Reacting Turbulent Jets to Facilitate Homogeneous Combustion in Industrial Furnaces.” 2015. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/111503.

MLA Handbook (7^th Edition):

Lee, Insu. “An Experimental and Numerical Study of Confined Non-reacting and Reacting Turbulent Jets to Facilitate Homogeneous Combustion in Industrial Furnaces.” 2015. Web. 07 Mar 2021.

Vancouver:

Lee I. An Experimental and Numerical Study of Confined Non-reacting and Reacting Turbulent Jets to Facilitate Homogeneous Combustion in Industrial Furnaces. [Internet] [Doctoral dissertation]. University of Michigan; 2015. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/111503.

Council of Science Editors:

Lee I. An Experimental and Numerical Study of Confined Non-reacting and Reacting Turbulent Jets to Facilitate Homogeneous Combustion in Industrial Furnaces. [Doctoral Dissertation]. University of Michigan; 2015. Available from: http://hdl.handle.net/2027.42/111503

9. Cao, Weiyu. A Study of Thermal Radiation Enhancement in the Homogeneous Combustion.

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

URL: http://hdl.handle.net/2027.42/151465

► Amongst all the attempts to fulfill the goal of enhancing thermal efficiency and decreasing pollutant emissions in a combustion system, Homogeneous Combustion (HC), or Flameless… (more)

▼ Amongst all the attempts to fulfill the goal of enhancing thermal efficiency and decreasing pollutant emissions in a combustion system, Homogeneous Combustion (HC), or Flameless Oxidization (FLOX) or Moderate Intense Low-oxygen Dilution (MILD) Combustion is thought to be one of the most promising technologies. HC is achieved by strong exhaust gas recirculation, where reactants are intensely diluted and hence reactions occur volumetrically without a visible flame front. Relative to the conventional counterpart, HC increases the in-furnace thermal uniformity and efficiency, and simultaneously suppresses NOx emissions. Thermal radiation enhancement can be one possible approach to further improve the thermal performance of a HC at no or little expense of pollutant emissions, especially when applied in the heating facilities such as industrial furnace. In practical heating systems where thermal radiation is pursued, such as industrial furnace, certain level of soot production in the combustion zone is favored if adequate aftertreatment is available to limit the soot emissions in the exhaust under the regulated values. The present study focuses on the possibility of thermal radiation enhancement through soot formation under Homogeneous Combustion regime through experimental tests implemented in a large-scale furnace (0.84 m in diameter and 1.4 m in length), which can provide direct insights to the development of practical industrial heating systems. The possibility of sooty HC is studied first. Experimental tests, under various concentrations of propane or ethylene in the fuel, oxygen enrichment level and process temperature, are implemented. Results show that sooty HC can be achieved under the conditions of: 1) fuel rich combustion with equivalence ratio of 1.1; 2) fuel mixture with ethylene while the mass fraction of ethylene should be maintained below 20%; 3) process temperature over 1400 K. The characteristics of sooty HC is studied next. Experimental tests under the sooty HC conditions are implemented to measure the soot content (by laser extinction), the thermal radiation heat flux (by a Schmidt-Boelter Gauge), the thermal field (by in-situ temperature probe), the furnace efficiency (by a cooling plate equipped with water jacket) and the pollutant emissions (by various gas analyzers). Results showed an increasing trend in the in-furnace soot content with increasing ethylene content in the fuel. A close-to-linear relationship is found between the measured radiation heat flux and the soot volume fraction in sooty HCs. However, in the test runs with 20% ethylene in the fuel, visible flames can be found and hence this can no longer be identified as sooty HC. To help understand the flow field of the Homogeneous Combustion in the present study, numerical modeling for the turbulent reacting flows in the HC is implemented with CFD simulation. It is found that increasing the air jet momentum will help in achieving Homogeneous Combustion. The Homogeneous Combustion has a large tolerance to the unbalanced air jet… Advisors/Committee Members: Atreya, Arvind (committee member), Borgnakke, Claus (committee member), Driscoll, James F (committee member), Wooldridge, Margaret S (committee member).

Subjects/Keywords: Homogeneous Combustion; Thermal Radiation; NOx emission; Soot; Thermal efficiency; Mechanical Engineering; Engineering

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APA (6^th Edition):

Cao, W. (2019). A Study of Thermal Radiation Enhancement in the Homogeneous Combustion. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/151465

Chicago Manual of Style (16^th Edition):

Cao, Weiyu. “A Study of Thermal Radiation Enhancement in the Homogeneous Combustion.” 2019. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/151465.

MLA Handbook (7^th Edition):

Cao, Weiyu. “A Study of Thermal Radiation Enhancement in the Homogeneous Combustion.” 2019. Web. 07 Mar 2021.

Vancouver:

Cao W. A Study of Thermal Radiation Enhancement in the Homogeneous Combustion. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/151465.

Council of Science Editors:

Cao W. A Study of Thermal Radiation Enhancement in the Homogeneous Combustion. [Doctoral Dissertation]. University of Michigan; 2019. Available from: http://hdl.handle.net/2027.42/151465

10. Liu, Zhichao. Frost Deterioration in Concrete Due to Deicing Salt Exposure: Mechanism, Mitigation and Conceptual Surface Scaling Model.

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

URL: http://hdl.handle.net/2027.42/110430

► Michigan is located in a wet-freeze climate zone. During winter the deicing-salt application is needed to melt snow on highways. Freezing in the presence of… (more)

▼ Michigan is located in a wet-freeze climate zone. During winter the deicing-salt application is needed to melt snow on highways. Freezing in the presence of a deicing salt solution is considered a severe concrete exposure condition. Prolonged exposure in pavement joints has been found to erode the concrete binder material (portland cement paste) when coupled with its low internal frost resistance (i.e. insufficient air and poorly drained joints). This creates a weak zone resulting in joint spalling from heavy wheel loading. Many highways have been found to suffer this type of distress within ten years requiring expensive joint repairs. This research investigates the material level mechanisms for frost deterioration under deicing salt exposure by the aid of systematic application of various experimental techniques, such as sub-freezing length change measurement, micro- and macro-characterization of scaling properties and nitrogen sorption test. A new conceptual model is provided for the surface deterioration that occurs within a thin surface layer when exposed to a deicing salt solution. The major stress producing mechanism is ice-growth within the capillary pores exacerbated by cryogenic suction of the liquid brine present on the surface, thus feeding further ice-growth and leading to high tensile stresses in the direction of least internal restraint and “popping” of thin mortar flakes. This process repeats itself for every freeze-thaw cycle. These findings pave the way for the proposal of sorptivity as a performance-based criterion to evaluate scaling resistance in concrete and its theoretical nature is enhanced by a refined model capable of capturing the effect of pore size characteristics (pore volume, its size distribution and connectivity). This further leads to the identification and application of effective mitigation techniques, including reconfiguration of paste pore system towards a more refined and discontinued structure and utilization of a hydrophobic pore liner in the silicate substrate of hydration products as surface treatment. Advisors/Committee Members: Hansen, Will (committee member), Borgnakke, Claus (committee member), McCormick, Jason Paul (committee member), Koenders, Eddy A.b. (committee member).

Subjects/Keywords: Salt frost scaling; Cryogenic suction; Sorptivity; Ice growth; Civil and Environmental Engineering; Engineering

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APA (6^th Edition):

Liu, Z. (2014). Frost Deterioration in Concrete Due to Deicing Salt Exposure: Mechanism, Mitigation and Conceptual Surface Scaling Model. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/110430

Chicago Manual of Style (16^th Edition):

Liu, Zhichao. “Frost Deterioration in Concrete Due to Deicing Salt Exposure: Mechanism, Mitigation and Conceptual Surface Scaling Model.” 2014. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/110430.

MLA Handbook (7^th Edition):

Liu, Zhichao. “Frost Deterioration in Concrete Due to Deicing Salt Exposure: Mechanism, Mitigation and Conceptual Surface Scaling Model.” 2014. Web. 07 Mar 2021.

Vancouver:

Liu Z. Frost Deterioration in Concrete Due to Deicing Salt Exposure: Mechanism, Mitigation and Conceptual Surface Scaling Model. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/110430.

Council of Science Editors:

Liu Z. Frost Deterioration in Concrete Due to Deicing Salt Exposure: Mechanism, Mitigation and Conceptual Surface Scaling Model. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/110430

11. White, Steven Bryan. Enhancement of Boiling Surfaces Using Nanofluid Particle Deposition.

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

URL: http://hdl.handle.net/2027.42/77748

► To meet increasing power demands across several industries, advanced thermal management systems based on boiling heat transfer have been proposed. Furthermore, nanofluids, a relatively new… (more)

▼ To meet increasing power demands across several industries, advanced thermal management systems based on boiling heat transfer have been proposed. Furthermore, nanofluids, a relatively new class of coolants created by suspending 1-100 nm sized particles in a base fluid, have been shown to improve a fluid’s thermal properties. This research focuses on two methods using nanofluids to deposit nanoparticles for the creation of enhanced surfaces for boiling heat transfer. Since many of these thermal management systems require a non-conductive fluid, the electrical conductivity of nanofluids is also studied. Pool boiling studies of nanofluids have demonstrated either enhanced or diminished boiling heat transfer, yet have been unable to distinguish the contributions of increased surface roughness and suppression of bubble transport by suspended particles. This uncertainty is resolved by studying the boiling performance of a surface exposed to a series of boiling tests that alternate between water and a water-based nanofluid. The boiling performance of the coated surfaces increases significantly with each cycle. The measured surface roughness of the intervening nanoparticle layers is used with a model to explain the measured increase in performance. The results demonstrate that the effect of increased surface roughness due to nanoparticle layering can enhance boiling for the base fluid. A novel method to create enhanced boiling surfaces is electrophoretic deposition of nanoparticles from a nanofluid. A surface was coated using electrophoretic deposition from a ZnO-propylene glycol based nanofluid. With adequate coating time, such a surface modification method can increase the boiling heat transfer coefficient by about 200%, which was correlated to an increase in the nucleation site density. In addition, on chip cooling techniques require low conductivity coolants. However, the electrical conductivity of nanofluids has not been widely studied. The particle size and concentration effects on nanofluid electrical conductivity were experimentally investigated and compared to a model based on colloidal suspensions in a salt-free medium. The results showed the electrical conductivity increased with increasing volume fraction and decreasing particle size. At higher volume fractions, the increase of electrical conductivity begins to level off, which is attributed to ion condensation effects in the high surface charge regime. Advisors/Committee Members: Pipe, Kevin Patrick (committee member), Shih, Albert J. (committee member), Borgnakke, Claus (committee member), Tuteja, Anish (committee member).

Subjects/Keywords: Nanofluids; Boiling; Enhanced Surfaces; Electrical Conductivity; Thermal Management; Nanoparticles; Mechanical Engineering; Engineering

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APA (6^th Edition):

White, S. B. (2010). Enhancement of Boiling Surfaces Using Nanofluid Particle Deposition. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/77748

Chicago Manual of Style (16^th Edition):

White, Steven Bryan. “Enhancement of Boiling Surfaces Using Nanofluid Particle Deposition.” 2010. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/77748.

MLA Handbook (7^th Edition):

White, Steven Bryan. “Enhancement of Boiling Surfaces Using Nanofluid Particle Deposition.” 2010. Web. 07 Mar 2021.

Vancouver:

White SB. Enhancement of Boiling Surfaces Using Nanofluid Particle Deposition. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/77748.

Council of Science Editors:

White SB. Enhancement of Boiling Surfaces Using Nanofluid Particle Deposition. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/77748

12. Kuo, Chuan-Hsien. Manipulations of Viscoelastic Instability and Interfacial Surface Forces in Microfluidic Devices for Biomedical and Material Science Applications.

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

URL: http://hdl.handle.net/2027.42/77896

► As a highly viscoelastic liquid, flowing blood exerts a shearing force that has a significant effect on the functioning of vascular endothelial cells (ECs), which… (more)

▼ As a highly viscoelastic liquid, flowing blood exerts a shearing force that has a significant effect on the functioning of vascular endothelial cells (ECs), which regulates the human circulatory system. The first part of the thesis describes a microfluidic device along with a specially formulated media to provide an in-vitro testing microenvironment where cultured endothelial cell layers can be subjected to shearing forces from both stable and unstable flows. Complex and unstable flow patterns are generated within this microchannel device by engineering the viscoelastic properties of the EC culture media without the need of an extensive flow agitation apparatus. In-vitro shearing tests showed significant differences in the responses of Human Umbilical Vein Endothelial Cell (HUVEC) layers to laminar stable and complex unstable flows. The second part of the thesis describes a microfluidic method to generate uniform-sized polydimethylsiloxane (PDMS) microspheres over a size range of 85-200 microns by manipulation of the microchannel two-phase flow. Viscous PDMS prepolymer is pushed out of the middle channel of a 3-inlet-1-outlet converging microchannel flanked on each side by flow of an aqueous surfactant solution. Unique surface crack patterns are generated on the surfaces of PDMS microspheres, and they are decorated by coating them with fluorescent protein and gold nanoparticles, which could be further enhanced into gold or silver nanowires. The unique ability to generate controllable selective 3D deposition patterns on PDMS microspheres introduces a new class of microscale functional materials, and provides opportunities for a multitude of material science and biomedical applications. Finally, the effect of channel surface properties on air- liquid two–phase flows and plug flows in a microchannel are investigated. Manipulation of the surface properties creates a several distinct flow regimes in a Y-shaped microchannel; and affects different plug propagation conditions in a K-shaped design, with important clinical implications for pulmonary airway cells injury. Advisors/Committee Members: Borgnakke, Claus (committee member), Takayama, Shuichi (committee member), Larson, Ronald G. (committee member), Thouless, Michael D. (committee member).

Subjects/Keywords: Viscoelastic Instability; Endothelial Cell Layer; Interfacial Forces; Microfluidics; Microspheres; Biomedical Engineering; Mechanical Engineering; Engineering

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APA (6^th Edition):

Kuo, C. (2010). Manipulations of Viscoelastic Instability and Interfacial Surface Forces in Microfluidic Devices for Biomedical and Material Science Applications. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/77896

Chicago Manual of Style (16^th Edition):

Kuo, Chuan-Hsien. “Manipulations of Viscoelastic Instability and Interfacial Surface Forces in Microfluidic Devices for Biomedical and Material Science Applications.” 2010. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/77896.

MLA Handbook (7^th Edition):

Kuo, Chuan-Hsien. “Manipulations of Viscoelastic Instability and Interfacial Surface Forces in Microfluidic Devices for Biomedical and Material Science Applications.” 2010. Web. 07 Mar 2021.

Vancouver:

Kuo C. Manipulations of Viscoelastic Instability and Interfacial Surface Forces in Microfluidic Devices for Biomedical and Material Science Applications. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/77896.

Council of Science Editors:

Kuo C. Manipulations of Viscoelastic Instability and Interfacial Surface Forces in Microfluidic Devices for Biomedical and Material Science Applications. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/77896

University of Michigan

13. Hassani, Mohammad. An imaging method for analyzing spherical and nonspherical particles.

Degree: PhD, Mechanical Engineering, 1993, University of Michigan

URL: http://hdl.handle.net/2027.42/103413

► An automatic image processing technique and a comprehensive formulation of depth of field effects for particle analysis are presented. The image processing method operates on… (more)

▼ An automatic image processing technique and a comprehensive formulation of depth of field effects for particle analysis are presented. The image processing method operates on original, unenhanced particle images where the background intensity can be non-uniform, and particle size, location, and level of focus are random. Objects that do not meet a standard of focus needed for correct measurements are automatically rejected, and the threshold for each object is determined uniquely based on the particle and local background information. Border points are defined such that a boundary drawn by connecting border points can never have coincident parts, and is smoother. Moreover, the method is capable of recognizing when light is transmitted or reflected through transparent particles makes them falsely appear as if they had holes in them. The method computes various features for non-spherical particles shapes. Depth of field effects due to particle size, shape, and illumination intensity is formulated as an integral equation. The method is adaptable to wide variety of conditions by means of a few functions that are obtained during calibration. Shape factor parameters are introduced to describe particle shapes. The definition of a shape factor is based on the geometric properties of particles such that it is a true measure of the shape effect on particle properties. For spherical particles the domain of particle size, position relative to the object plane and contrast level where valid measurements can be obtained is a three dimensional dynamic envelope. The analogue dynamic envelope for non-spherical particles is an N-dimensional space which includes the size, position relative to the object plane, contrast, and N-3 shape factors. Most general way to correct the depth of field bias is by traversing the object plane along the optical axis. However, conditions are identified that allow proper correction to be made without having to move the object plane. Advisors/Committee Members: Borgnakke, Claus (advisor), Talley, Douglas G. (advisor).

Subjects/Keywords: Engineering, Aerospace; Engineering, Mechanical

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APA (6^th Edition):

Hassani, M. (1993). An imaging method for analyzing spherical and nonspherical particles. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/103413

Chicago Manual of Style (16^th Edition):

Hassani, Mohammad. “An imaging method for analyzing spherical and nonspherical particles.” 1993. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/103413.

MLA Handbook (7^th Edition):

Hassani, Mohammad. “An imaging method for analyzing spherical and nonspherical particles.” 1993. Web. 07 Mar 2021.

Vancouver:

Hassani M. An imaging method for analyzing spherical and nonspherical particles. [Internet] [Doctoral dissertation]. University of Michigan; 1993. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/103413.

Council of Science Editors:

Hassani M. An imaging method for analyzing spherical and nonspherical particles. [Doctoral Dissertation]. University of Michigan; 1993. Available from: http://hdl.handle.net/2027.42/103413

University of Michigan

14. Puzinauskas, Paulius Vytautas. Combustion and heat transfer studies in a spark ignition engine.

Degree: PhD, Mechanical engineering, 1989, University of Michigan

URL: http://hdl.handle.net/2027.42/128441

► This study utilized time-resolved heat-flux measurements, heat-release analysis and high-speed flame photography to investigate experimentally the combustion and heat-transfer characteristics of an optically accessible single-cylinder… (more)

▼ This study utilized time-resolved heat-flux measurements, heat-release analysis and high-speed flame photography to investigate experimentally the combustion and heat-transfer characteristics of an optically accessible single-cylinder engine. The engine had a pent-roof shaped combustion chamber with two intake and two exhaust valves. The primary variable examined was the intake-flow configuration which was varied by means of shrouded intake valves. The experimental data gathered was used to assess the applicability of a thermal boundary-layer based heat-transfer model. The model is significant in that it is not based on a Ν ∼ Re correlation of the heat transfer in steady incompressible pipe flow as most heat-transfer models used in quasi-dimensional engine simulations. The measured local heat-flux histories on the combustion side of the head were found to have significant spatial variations, which are believed to be caused by spatial nonuniformities in combustion and the flow field. The introduction of swirl or tumbling motion to the intake charge accelerated early flame development and increased peak combustion rate. These augmentations consequently caused higher local surface temperatures and increased steady-state as well as local peak heat fluxes. The presence of large cycle-to-cycle variations in the measured local heat-flux histories necessitated evaluating the heat-transfer model with information from individual cycle calculations. The model in its original formulation was able to accurately predict the heat transfer if convective effects were negligible. After the model was modified to account for these effects, the model showed good agreement with measurements made at a location exposed to a strong convective influence. The model gave significantly improved heat-transfer predictions over the currently available correlations tested, but the additional accuracy comes with added computing cost and increased implementation complexity. Advisors/Committee Members: Borgnakke, Claus (advisor), Patterson, Donald (advisor).

Subjects/Keywords: Combustion; Engine; Heat; Ignition; Spark; Studies; Transfer

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APA (6^th Edition):

Puzinauskas, P. V. (1989). Combustion and heat transfer studies in a spark ignition engine. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/128441

Chicago Manual of Style (16^th Edition):

Puzinauskas, Paulius Vytautas. “Combustion and heat transfer studies in a spark ignition engine.” 1989. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/128441.

MLA Handbook (7^th Edition):

Puzinauskas, Paulius Vytautas. “Combustion and heat transfer studies in a spark ignition engine.” 1989. Web. 07 Mar 2021.

Vancouver:

Puzinauskas PV. Combustion and heat transfer studies in a spark ignition engine. [Internet] [Doctoral dissertation]. University of Michigan; 1989. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/128441.

Council of Science Editors:

Puzinauskas PV. Combustion and heat transfer studies in a spark ignition engine. [Doctoral Dissertation]. University of Michigan; 1989. Available from: http://hdl.handle.net/2027.42/128441

University of Michigan

15. Kim, Youngil. Generalized equation of state for refrigerants with applications.

Degree: PhD, Mechanical engineering, 1993, University of Michigan

URL: http://hdl.handle.net/2027.42/129071

► Recent studies have indicated that chlorofluorocarbon compounds that are widely used as refrigerants in vapor-compression refrigeration cycles and as propellants are the major suspect to… (more)

▼ Recent studies have indicated that chlorofluorocarbon compounds that are widely used as refrigerants in vapor-compression refrigeration cycles and as propellants are the major suspect to the depletion of the upper atmosphere ozone layer which protects the earth from the harmful radiation. Studies need to be made to replace these refrigerants with alternatives that are safe to our environment. In order to develop new refrigerants, we need to have a better generalized equation of state that can predict thermodynamic properties of the methane and ethane series refrigerants with a minimum number of characteristic parameters. In this work, a four-parameter generalized equation of state with three reference fluids is developed and compared with the experimental data. Significant improvement has been achieved over other well known generalized equations of state such as Lee-Kesler and Wu-Stiel. Some refrigerant mixtures have favorable thermodynamic properties and possess great potential as the working fluids in the vapor-compression refrigeration cycle. The generalized equation of state, combined with the mixing rules suggested in this study will be used in predicting thermodynamic properties of the mixture. The generalized equation of state requires only four characteristic parameters. For some refrigerants, however, even these parameters are not available. This problem arises if the refrigerant of interest has not yet been manufactured or the experimental data are unreliable or insufficient. To solve this problem, estimation of these parameters based on the group contribution method which only requires the information of the molecular structure is given. Coefficients from original work are recalculated to give better results for the refrigerants. Finally, the generalized equation of state is applied to an ideal vapor-compression refrigeration cycle. Small deviation from other existing equations of state which have been developed by fitting an extensive number of experimental data verifies the accuracy of this work. If the normal boiling temperature of a substance is known, other thermodynamic properties can be predicted with significant accuracy. Composition dependence of the coefficient of performance using binary non-azeotropic mixtures of R22 + R12 and R22 + R114 are calculated and the optimum composition is suggested. This work will provide a valuable tool for studying refrigeration cycles with different pure and mixed refrigerants. It can also be used to search for new alternative refrigerants that do not destruct the ozone layer. Advisors/Committee Members: Sonntag, Richard E. (advisor), Borgnakke, Claus (advisor).

Subjects/Keywords: Applications; Equation; Generalized; Of; Refrigerants; State

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APA (6^th Edition):

Kim, Y. (1993). Generalized equation of state for refrigerants with applications. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/129071

Chicago Manual of Style (16^th Edition):

Kim, Youngil. “Generalized equation of state for refrigerants with applications.” 1993. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/129071.

MLA Handbook (7^th Edition):

Kim, Youngil. “Generalized equation of state for refrigerants with applications.” 1993. Web. 07 Mar 2021.

Vancouver:

Kim Y. Generalized equation of state for refrigerants with applications. [Internet] [Doctoral dissertation]. University of Michigan; 1993. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/129071.

Council of Science Editors:

Kim Y. Generalized equation of state for refrigerants with applications. [Doctoral Dissertation]. University of Michigan; 1993. Available from: http://hdl.handle.net/2027.42/129071

University of Michigan

16. Park, Kyoungkuhn. Generalized thermodynamic properties of refrigerants.

Degree: PhD, Mechanical Engineering, 1993, University of Michigan

URL: http://hdl.handle.net/2027.42/103466

► Recent theories and experimental observations have indicated that chlorofluorocarbon refrigerants (CFCs) are a major contributor to the depletion of the upper atmosphere ozone layer, which… (more)

▼ Recent theories and experimental observations have indicated that chlorofluorocarbon refrigerants (CFCs) are a major contributor to the depletion of the upper atmosphere ozone layer, which shields the earth from harmful radiation. Therefore, it is urgently required to replace these CFCs with new stratospherically safe chemicals. However, much of the thermodynamic property data needed for the analysis of thermal systems are lacking for many refrigerant candidates. The primary objective of this research is to predict the thermodynamic properties of halogenated hydrocarbon refrigerants covering the entire range of reduced pressure and reduced temperature and practical interest. The prediction can be done by the generalization of thermodynamic properties of refrigerants based on the corresponding states principle. Therefore, a new four-parameter corresponding states correlation has been developed which assumes that the compressibility factor for a substance can be expressed as a function of reduced pressure, reduced temperature, Pitzer acentric factor ω, and a new fourth parameter π. The third parameter ω is obtained from the vapor pressure correlation. The fourth parameter π is evaluated from the compressibility factor of a liquid in a saturation state, which can be determined from the vapor pressure correlation and the saturated liquid density correlation. The generalized correlation predicts the compressibility factors with an overall error less than 1%. It is of importance to note that all the four parameters are obtained not from experimental PVT data but from information on the vapor-liquid coexistence curve. A second objective of the present research was to investigate the form of equations of state for specific substances. In particular, equations of the extended van der Waals form have been studied. As a result, a new equation of state has been developed and tested over ranges of pressure and density up to 5 and 1.5 times critical, respectively. The equation has 12 adjustable parameters and correlates PVT data successfully. The new equation of state developed here can be used to accurately calculate the thermodynamic properties of refrigerants. Advisors/Committee Members: Sonntag, Richard E. (advisor), Borgnakke, Claus (advisor).

Subjects/Keywords: Engineering, Chemical; Engineering, Mechanical

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APA (6^th Edition):

Park, K. (1993). Generalized thermodynamic properties of refrigerants. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/103466

Chicago Manual of Style (16^th Edition):

Park, Kyoungkuhn. “Generalized thermodynamic properties of refrigerants.” 1993. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/103466.

MLA Handbook (7^th Edition):

Park, Kyoungkuhn. “Generalized thermodynamic properties of refrigerants.” 1993. Web. 07 Mar 2021.

Vancouver:

Park K. Generalized thermodynamic properties of refrigerants. [Internet] [Doctoral dissertation]. University of Michigan; 1993. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/103466.

Council of Science Editors:

Park K. Generalized thermodynamic properties of refrigerants. [Doctoral Dissertation]. University of Michigan; 1993. Available from: http://hdl.handle.net/2027.42/103466

University of Michigan

17. Selamet, Emel. Simulation of laminar buoyancy-driven flows in an enclosure.

Degree: PhD, Mechanical engineering, 1991, University of Michigan

URL: http://hdl.handle.net/2027.42/128775

► A numerical study has been carried out on the natural convection in a vertical slot with a narrow upper section. The fluid in the slot… (more)

▼ A numerical study has been carried out on the natural convection in a vertical slot with a narrow upper section. The fluid in the slot is initially at a uniform temperature and motionless. The left walls are subjected to a step change in temperature while the right walls are kept at the initial temperature. The top and bottom are insulated. The resulting flow pattern and heat transfer are studied for different Rayleigh and Prandtl numbers, Ra and Pr, respectively. A program is developed for the simulation of flow and temperature fields by using the projection or fractional-step formulation which incorporates a Godunov-type discretization of convective terms. The unsteady Navier-Stokes equations under the Boussinesq approximation are solved with primitive variables. Different flow regimes are obtained depending on Ra and Pr. The flow regimes observed change from conduction-dominated to convection-dominated with increasing Ra. The steady flow for water (Pr = 6), alcohol (Pr = 20) and viscous oil (Pr = 100) at Ra = 10⁴ is found to be independent of Pr although the time evolution of the flow is Pr-dependent. In the limit of very small Prandtl numbers, a series of runs have been performed to predict the onset of oscillations and the transitions to unsteady natural convection in a fixed geometry. Transitions from two to one, from one to three, and from three to two cell structure in the flow are observed depending on Grashof number. The effect of narrow upper section is examined as a function of the ratio of its height to the total height. It is found that the strength of the circulation in the narrow section increases for air and water as the height ratio increases whereas for limit case of small Pr, it is weak over the entire range of the height ratio considered. Comparison of the results between rectangular and present configuration with the height ratio of 1.3/7 reveals that the liquid metals are most significantly affected by the narrow section: as opposed to two cells observed in a rectangular cavity, three cells are found in the wide section. Advisors/Committee Members: Arpaci, Vedat S. (advisor), Borgnakke, Claus (advisor).

Subjects/Keywords: Buoyancy; Driven; Enclosure; Laminar Flows; Simulation

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APA (6^th Edition):

Selamet, E. (1991). Simulation of laminar buoyancy-driven flows in an enclosure. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/128775

Chicago Manual of Style (16^th Edition):

Selamet, Emel. “Simulation of laminar buoyancy-driven flows in an enclosure.” 1991. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/128775.

MLA Handbook (7^th Edition):

Selamet, Emel. “Simulation of laminar buoyancy-driven flows in an enclosure.” 1991. Web. 07 Mar 2021.

Vancouver:

Selamet E. Simulation of laminar buoyancy-driven flows in an enclosure. [Internet] [Doctoral dissertation]. University of Michigan; 1991. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/128775.

Council of Science Editors:

Selamet E. Simulation of laminar buoyancy-driven flows in an enclosure. [Doctoral Dissertation]. University of Michigan; 1991. Available from: http://hdl.handle.net/2027.42/128775

18. 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 March 07, 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. 07 Mar 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 Mar 07]. 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

19. Lawler, Benjamin John. A Methodology for Assessing Thermal Stratification in an HCCI Engine and Understanding the Impact of Engine Design and Operating Conditions.

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

URL: http://hdl.handle.net/2027.42/102425

► HCCI is a promising advanced engine concept with the potential to pair high thermal efficiencies with ultra-low emissions. However, HCCI has so far been demonstrated… (more)

▼ HCCI is a promising advanced engine concept with the potential to pair high thermal efficiencies with ultra-low emissions. However, HCCI has so far been demonstrated only over a narrow operating range due to a lack of control over HCCI burn rates. While there is an emerging consensus about the critical role of thermal stratification on HCCI burn rates, there was a gap related to availability of a method to rapidly assess the impact of engine design or operating conditions on thermal stratification in a practical HCCI engine. The objectives of this research are to develop a novel post-processing technique for studying thermal stratification in a fired, metal HCCI engine, and use the proposed technique to understand the impact of operating conditions on the in-cylinder unburned temperature distribution. The technique is called the Thermal Stratification Analysis (TSA) and it uses the autoignition integral coupled to the mass fraction burned curve to determine a distribution of mass and temperature in the cylinder prior to combustion. The technique is then validated by comparing the TSA results to predictions from CFD simulations and experimentally measured unburned temperature distributions in an optical engine. A large amount of data was collected and processed with the TSA to determine the effects of engine design and operating conditions on the in-cylinder unburned temperature distribution and HCCI burn rates. The results show that the thermal width increases with a higher internal residual gas fraction, increasing intake temperature, advancing combustion phasing, increasing the maximum TDC temperature, and increasing the in-cylinder swirl. Finally, an innovative method for active control of the thermal stratification and HCCI burn rates with a glow plug is proposed. The results show that the glow plug is able to control combustion phasing and, more importantly, broaden the temperature distribution and lengthen the burn duration a considerable amount. The glow plug improves some of the emissions characteristics slightly and the combustion efficiency as well. The main drawbacks of using a glow plug in HCCI are the efficiency penalty associated with the energy consumed by the glow plug and the observed increase in the cycle-to-cycle variations. Advisors/Committee Members: Atreya, Arvind (committee member), Filipi, Zoran S. (committee member), Driscoll, James F. (committee member), Lavoie, George A. (committee member), Sick, Volker (committee member), Borgnakke, Claus (committee member).

Subjects/Keywords: Homogeneous Charge Compression Ignition; Heat Release Analysis; Thermal Stratification; Post-Processing; Mechanical Engineering; Engineering

…discuss the research efforts conducted over the last decade at the University of Michigan… …Technology, and the University of Michigan have recently taken chemiluminescence images of HCCI and… …the sensitivity of HCCI to thermal conditions at the University of Michigan and the thermal… …Thermal Characterization of HCCI The University of Michigan is a world leader in HCCI research…

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APA (6^th Edition):

Lawler, B. J. (2013). A Methodology for Assessing Thermal Stratification in an HCCI Engine and Understanding the Impact of Engine Design and Operating Conditions. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/102425

Chicago Manual of Style (16^th Edition):

Lawler, Benjamin John. “A Methodology for Assessing Thermal Stratification in an HCCI Engine and Understanding the Impact of Engine Design and Operating Conditions.” 2013. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/102425.

MLA Handbook (7^th Edition):

Lawler, Benjamin John. “A Methodology for Assessing Thermal Stratification in an HCCI Engine and Understanding the Impact of Engine Design and Operating Conditions.” 2013. Web. 07 Mar 2021.

Vancouver:

Lawler BJ. A Methodology for Assessing Thermal Stratification in an HCCI Engine and Understanding the Impact of Engine Design and Operating Conditions. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/102425.

Council of Science Editors:

Lawler BJ. A Methodology for Assessing Thermal Stratification in an HCCI Engine and Understanding the Impact of Engine Design and Operating Conditions. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/102425

20. 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 March 07, 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. 07 Mar 2021.

Vancouver:

Lee C. Turbine-Compound Free-Piston Linear Alternator Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Mar 07]. 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

21. 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 March 07, 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. 07 Mar 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 Mar 07]. 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

22. 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 March 07, 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. 07 Mar 2021.

Vancouver:

Mamalis S. Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2012. [cited 2021 Mar 07]. 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

23. Mosburger, Michael J. Alkali Metal Spectroscopy for High-speed Imaging of Burned Gas Temperature, Equivalence Ratio and Mass Fraction Burned in Internal Combustion Engines.

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

URL: http://hdl.handle.net/2027.42/97841

► Alkali metal atoms show an intense natural fluorescence in the burned gas region of internal combustion engines. This fluorescence offers great opportunity for spectroscopic combustion… (more)

▼ Alkali metal atoms show an intense natural fluorescence in the burned gas region of internal combustion engines. This fluorescence offers great opportunity for spectroscopic combustion analysis in internal combustion engines without the requirement of laser excitation or image intensifiers. To quantify this fluorescence intensity, spectroscopic and thermodynamic properties of the alkali metals lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs) and their oxidation products and ions were analyzed. Collisional energy transfer and reabsorption effects (including temperature- and pressure dependent lineshapes) were calculated over the range of engine environments. Three compounds containing Li, Na and K, respectively, were selected as fuel additives for engine experiments. The experiments were conducted on an optical, single cylinder, spark-ignition, direct-injection research engine, and the fluorescence of the three alkali components was recorded simultaneously using three CMOS high-speed cameras. The two-component fluorescence intensity ratios (Na/K, Li/K and Na/Li) are shown to depend on temperature, pressure and equivalence ratio. However, the three-component ratio Na•Li/K2 is nearly independent of pressure and equivalence ratio in the tested range of operating conditions and can serve as a direct marker for burned gas temperature. Subsequently, equivalence ratio can be determined from any of the bi-component fluorescence ratios. The spatially integrated fluorescence intensity of the single components is a function of burned gas temperature, cylinder pressure, equivalence ratio and mass fraction of burned fuel. When temperature and equivalence ratio are determined from the fluorescence intensity ratios, the spatially integrated fluorescence signal of sodium can serve as a marker for the mass fraction of burned fuel. The tool was applied to various cases of direct injected, stratified engine combustion to illustrate the potential of this technique for optimization of the combustion strategy and engine hardware configuration. Advisors/Committee Members: Sick, Volker (committee member), Ihme, Matthias (committee member), Drake, Michael C. (committee member), Settersten, Thomas B. (committee member), Borgnakke, Claus (committee member).

Subjects/Keywords: Spectroscopy; Combustion; Internal Combustion Engine; Sodium and Alkali Fluorescence; Temperature; Equivalence Ratio; Mechanical Engineering; Engineering

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APA (6^th Edition):

Mosburger, M. J. (2013). Alkali Metal Spectroscopy for High-speed Imaging of Burned Gas Temperature, Equivalence Ratio and Mass Fraction Burned in Internal Combustion Engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/97841

Chicago Manual of Style (16^th Edition):

Mosburger, Michael J. “Alkali Metal Spectroscopy for High-speed Imaging of Burned Gas Temperature, Equivalence Ratio and Mass Fraction Burned in Internal Combustion Engines.” 2013. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/97841.

MLA Handbook (7^th Edition):

Mosburger, Michael J. “Alkali Metal Spectroscopy for High-speed Imaging of Burned Gas Temperature, Equivalence Ratio and Mass Fraction Burned in Internal Combustion Engines.” 2013. Web. 07 Mar 2021.

Vancouver:

Mosburger MJ. Alkali Metal Spectroscopy for High-speed Imaging of Burned Gas Temperature, Equivalence Ratio and Mass Fraction Burned in Internal Combustion Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/97841.

Council of Science Editors:

Mosburger MJ. Alkali Metal Spectroscopy for High-speed Imaging of Burned Gas Temperature, Equivalence Ratio and Mass Fraction Burned in Internal Combustion Engines. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/97841

24. Kim, Youngki. Power Capability Estimation Accounting for Thermal and Electrical Constraints of Lithium-Ion Batteries.

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

URL: http://hdl.handle.net/2027.42/107128

► Lithium-ion (Li-ion) batteries have become one of the most critical components in vehicle electrification due to their high specific power and energy density. The performance… (more)

▼ Lithium-ion (Li-ion) batteries have become one of the most critical components in vehicle electrification due to their high specific power and energy density. The performance and longevity of these batteries rely on constraining their operation such that voltage and temperature are regulated within prescribed intervals. Enforcement of constraints on the power capability is a viable solution to protect Li-ion batteries from overheating as well as over-charge/discharge. Moreover, the ability to estimate power capability is vital in formulating power management strategies that account for battery performance limitations while minimizing fuel consumption and emissions. To estimate power capability accounting for thermal and electrical constraints, the characterization of thermal and electrical system behavior is required. In the course of addressing this problem, first, a computationally efficient thermal model for a cylindrical battery is developed. The solution of the convective heat transfer problem is approximated by polynomials with identifiable parameters that have physical meaning. The parameterized thermal model is shown to accurately predict the measured core and surface temperatures. The model-based thermal estimation methodology is augmented for cases of unknown cooling conditions. The proposed method is shown with experimental data to accurately provide estimates of the core temperature even under faults in the cooling system. To jointly account for the thermal and electrical constraints, we utilize time scale separation, and propose a real-time implementable method to predict power capability of a Li-ion battery. The parameterized battery thermal model and estimation algorithms are integrated into a power management system for a series hybrid electric vehicle. An algorithm for sequential estimation of coupled model parameters and states is developed using sensitivity-based parameter grouping. The fully integrated co-simulation of the battery electro-thermal behavior and the on-line adaptive estimators reveal that the power management system can effectively determine power flow among hybrid powertrain components without violating operational constraints. Advisors/Committee Members: Stefanopoulou, Anna G. (committee member), Filipi, Zoran S. (committee member), Monroe, Charles W. (committee member), Borgnakke, Claus (committee member), Ersal, Tulga (committee member).

Subjects/Keywords: Lithium Ion Battery; Dual Estimation; Mechanical Engineering; Engineering

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APA (6^th Edition):

Kim, Y. (2014). Power Capability Estimation Accounting for Thermal and Electrical Constraints of Lithium-Ion Batteries. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/107128

Chicago Manual of Style (16^th Edition):

Kim, Youngki. “Power Capability Estimation Accounting for Thermal and Electrical Constraints of Lithium-Ion Batteries.” 2014. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/107128.

MLA Handbook (7^th Edition):

Kim, Youngki. “Power Capability Estimation Accounting for Thermal and Electrical Constraints of Lithium-Ion Batteries.” 2014. Web. 07 Mar 2021.

Vancouver:

Kim Y. Power Capability Estimation Accounting for Thermal and Electrical Constraints of Lithium-Ion Batteries. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/107128.

Council of Science Editors:

Kim Y. Power Capability Estimation Accounting for Thermal and Electrical Constraints of Lithium-Ion Batteries. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/107128

25. Hoffman, Mark A. Characterization of Combustion Chamber Deposits Formed During Homogeneous Charge Compression Ignition and the Impact of a Thermal Barrier Coating on Deposit Accumulation and HCCI Operability.

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

URL: http://hdl.handle.net/2027.42/96098

► Combustion chamber deposits, CCD, have been shown to influence the operational range of homogeneous charge compression ignition, HCCI. CCD insulate the combustion chamber during the… (more)

▼ Combustion chamber deposits, CCD, have been shown to influence the operational range of homogeneous charge compression ignition, HCCI. CCD insulate the combustion chamber during the intake and compression strokes, preserving enough charge temperature to shift the HCCI operational range to lower loads where the HCCI fuel economy benefit over traditional spark-ignited combustion is at a maximum. However, the drive cycle dependent CCD accumulation and burn-off creates uncontrolled shifting of the HCCI operability range, which must be mitigated in a practical multi-mode engine. Ideally, the beneficial shift of HCCI operation to lower loads provided by CCD could be obtained while avoiding uncontrolled shifting of the operational range. To provide fundamental insight into CCD properties, CCD thermal diffusivity was non-destructively measured during HCCI combustion (in-situ firing), during engine motoring (in-situ motoring) and in a specially designed radiation chamber (ex-situ). The diffusivity measurement methodology utilized the phase lag in sub-CCD temperature signals and the one dimensional heat diffusion equation. Comparisons of the CCD diffusivity values determined from the different measurement environments allowed the separation of several thermal and morphological CCD characteristics. The interaction of fuel with the CCD morphology was shown to have no significant impact on the diffusivity of CCD accumulated on the cylinder head. CCD less than thirty micrometers were spatially sparse and contained line-of-sight pathways though which the ex-situ radiation could pass and the in-situ convection could not. Thicker CCD exhibited differential sensitivity to radiation and convection heat transfer modes, which was utilized to quantify the effective porosity of the CCD through a novel radiation penetration factor. The impact of thermal barrier coatings on CCD accumulation and HCCI operability was assessed by testing a piston coated with magnesium zirconate, MgZr. The radiation penetration factor determined the MgZr coating to have 2.5 times the effective porosity of CCD. Reductions in CCD accumulation resulted from the elevated surface temperature of the MgZr. In addition, reduced cylinder head CCD accumulation was speculatively attributed to interaction between the surface roughness of the MgZr piston and the fuel spray. Overall, the HCCI operability shift due to CCD accumulation was reduced by the MgZr piston. Advisors/Committee Members: Borgnakke, Claus (committee member), Filipi, Zoran S. (committee member), Ihme, Matthias (committee member), Reuss, David L. (committee member), Sick, Volker (committee member).

Subjects/Keywords: Combustion Chamber Deposits; Combustion; Homogeneous Charge Compression Ignition; Thermal Barrier Coating; Heat Transfer; Porosity; Mechanical Engineering; Engineering

…University of Michigan for the in-situ determination of the thermal diffusivity of the CCD layer…

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APA (6^th Edition):

Hoffman, M. A. (2012). Characterization of Combustion Chamber Deposits Formed During Homogeneous Charge Compression Ignition and the Impact of a Thermal Barrier Coating on Deposit Accumulation and HCCI Operability. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/96098

Chicago Manual of Style (16^th Edition):

Hoffman, Mark A. “Characterization of Combustion Chamber Deposits Formed During Homogeneous Charge Compression Ignition and the Impact of a Thermal Barrier Coating on Deposit Accumulation and HCCI Operability.” 2012. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/96098.

MLA Handbook (7^th Edition):

Hoffman, Mark A. “Characterization of Combustion Chamber Deposits Formed During Homogeneous Charge Compression Ignition and the Impact of a Thermal Barrier Coating on Deposit Accumulation and HCCI Operability.” 2012. Web. 07 Mar 2021.

Vancouver:

Hoffman MA. Characterization of Combustion Chamber Deposits Formed During Homogeneous Charge Compression Ignition and the Impact of a Thermal Barrier Coating on Deposit Accumulation and HCCI Operability. [Internet] [Doctoral dissertation]. University of Michigan; 2012. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/96098.

Council of Science Editors:

Hoffman MA. Characterization of Combustion Chamber Deposits Formed During Homogeneous Charge Compression Ignition and the Impact of a Thermal Barrier Coating on Deposit Accumulation and HCCI Operability. [Doctoral Dissertation]. University of Michigan; 2012. Available from: http://hdl.handle.net/2027.42/96098

26. Kodavasal, Janardhan. Effect of Charge Preparation Strategy on HCCI Combustion.

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

URL: http://hdl.handle.net/2027.42/99766

► A critical factor determining Homogeneous Charge Compression Ignition (HCCI) combustion characteristics and emissions is preparation of the fuel-diluent charge prior to ignition. The choice of… (more)

▼ A critical factor determining Homogeneous Charge Compression Ignition (HCCI) combustion characteristics and emissions is preparation of the fuel-diluent charge prior to ignition. The choice of charge preparation strategy impacts diluent composition and stratification. Presently, there is a gap in fundamental understanding as to the impact of these strategies on charge distribution within the reaction space and consequent effects on HCCI combustion. In this doctoral work, fully-coupled CFD/chemical kinetics simulations are performed for various competing charge preparation strategies at a typical HCCI operating point to study the differences in burn duration and emissions arising from these strategies. The strategies studied are: air versus external EGR dilution, Negative Valve Overlap (NVO) versus Positive Valve Overlap (PVO) operation, and premixed fueling versus direct injection. The CFD reaction space is analyzed to determine the reactivity stratification prior to ignition arising from each of these strategies. A sequential CFD-multi-zone model is developed as a diagnostic tool wherein CFD simulation is performed over the gas exchange period until a transition point before TDC, after which the CFD reaction space is mapped onto a multi-zone chemical kinetic model. This tool is used to decouple various concurrent effects. For example, by selectively choosing to map thermal stratification from the CFD domain onto the multi-zone model while ignoring compositional stratification, the relative contributions of thermal and compositional stratification arising from NVO operation are isolated. Based on these insights from CFD, a standalone quasi-dimensional HCCI combustion model incorporating kinetics is built, featuring a computationally efficient methodology (developed as part of this work) to capture wall heat loss driven thermal stratification, as an alternative to expensive CFD simulation. It is shown that predictions from this model correspond well with results from detailed CFD/kinetics simulations over a range of operating conditions, for different engine geometries, while being up to two-orders of magnitude faster than CFD, making this model ideal for use in system-level codes. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Im, Hong G. (committee member), Driscoll, James F. (committee member), Martz, Jason Brian (committee member), Babajimopoulos, Aristotelis (committee member), Borgnakke, Claus (committee member), Lavoie, George A. (committee member).

Subjects/Keywords: HCCI; Combustion; Internal Combustion Engine; Stratification; CFD; Negative Valve Overlap; Mechanical Engineering; Engineering

…Figure 6.5 – University of Michigan FFVA engine CFD mesh…

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APA (6^th Edition):

Kodavasal, J. (2013). Effect of Charge Preparation Strategy on HCCI Combustion. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/99766

Chicago Manual of Style (16^th Edition):

Kodavasal, Janardhan. “Effect of Charge Preparation Strategy on HCCI Combustion.” 2013. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/99766.

MLA Handbook (7^th Edition):

Kodavasal, Janardhan. “Effect of Charge Preparation Strategy on HCCI Combustion.” 2013. Web. 07 Mar 2021.

Vancouver:

Kodavasal J. Effect of Charge Preparation Strategy on HCCI Combustion. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/99766.

Council of Science Editors:

Kodavasal J. Effect of Charge Preparation Strategy on HCCI Combustion. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/99766

27. Lewis, Anne Marie. The Potential of Lightweight Materials and Advance Engines to Reduce Life Cycle Energy and Greenhouse Gas Emissions for ICVs and Evs Using Design Harmonization Techniques.

Degree: PhD, Mechanical Engineering and Natural Resources and Environment, 2013, University of Michigan

URL: http://hdl.handle.net/2027.42/102298

► Lightweight materials and advanced combustion engines are being used with conventional and electrified vehicles to increase fuel economy, but such technologies may require more energy… (more)

▼ Lightweight materials and advanced combustion engines are being used with conventional and electrified vehicles to increase fuel economy, but such technologies may require more energy to produce and the impact of plug-in hybrid electric vehicles (PHEVs) is dependent on the electric grid. Life cycle assessment (LCA) is used to evaluate the total energy and GHG emissions for baseline and lightweight internal combustion vehicles (ICVs), hybrid electric vehicles (HEVs) and PHEVs when they are operated with baseline and advanced gasoline and ethanol engines. Design harmonization techniques are developed to compare diverse vehicle platforms by creating functionally equivalent conventional and hybrid vehicle models that account for increased structural support required for heavier, electrified powertrains. Lightweight vehicle models include primary and secondary mass reductions (including powertrain re-sizing) and are evaluated with body-in-white mass reduction scenarios with aluminum and advanced/high strength steel (A/HSS). Advanced engine/fuel strategies are incorporated in the vehicle models with fuel economy maps, developed with a novel method to ensure combustion limits are not violated under boosted and dilute conditions for high compression ratio engines. The harmonized vehicle models show that the structural mass required per kg of powertrain mass for electrified vehicles is 0.2-0.3 kg. As compared to lightweight materials, more significant life cycle improvements are achieved by using advanced gasoline and E85 engines, as fuel consumption is reduced up to 24%. As compared to A/HSS, more mass can be removed from the vehicle with aluminum, leading to greater fuel consumption and life cycle reductions. However, due to the higher energy and GHG emissions associated with aluminum production, more significant life cycle reductions occur for an equivalent decrease in vehicle mass with A/HSS. Life cycle impacts are reduced more for ICVs as compared to hybrid vehicles because fuel economy is most sensitive to mass for ICVs. Considering the same vehicle platform, the combination of lightweight materials and advanced engines yields the most life cycle energy and GHG reductions, as the technologies provide complimentary results due to engine downsizing. The least life cycle energy and GHG emissions occur for the lightest weight hybrid vehicles using the downsized/turbocharged gasoline or E85 engine. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Borgnakke, Claus (committee member), Keoleian, Gregory A. (committee member), Decicco, John M. (committee member), Kelly, Jarod Cory (committee member), Lavoie, George A. (committee member), Peng, Huei (committee member).

Subjects/Keywords: Life Cycle Assessment (LCA); Advanced Combustion Engines; Lightweight Materials; Hybrid Electric Vehicles; Vehicle Modeling; Ethanol; Mechanical Engineering; Transportation; Natural Resources and Environment; Engineering; Science

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APA (6^th Edition):

Lewis, A. M. (2013). The Potential of Lightweight Materials and Advance Engines to Reduce Life Cycle Energy and Greenhouse Gas Emissions for ICVs and Evs Using Design Harmonization Techniques. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/102298

Chicago Manual of Style (16^th Edition):

Lewis, Anne Marie. “The Potential of Lightweight Materials and Advance Engines to Reduce Life Cycle Energy and Greenhouse Gas Emissions for ICVs and Evs Using Design Harmonization Techniques.” 2013. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/102298.

MLA Handbook (7^th Edition):

Lewis, Anne Marie. “The Potential of Lightweight Materials and Advance Engines to Reduce Life Cycle Energy and Greenhouse Gas Emissions for ICVs and Evs Using Design Harmonization Techniques.” 2013. Web. 07 Mar 2021.

Vancouver:

Lewis AM. The Potential of Lightweight Materials and Advance Engines to Reduce Life Cycle Energy and Greenhouse Gas Emissions for ICVs and Evs Using Design Harmonization Techniques. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/102298.

Council of Science Editors:

Lewis AM. The Potential of Lightweight Materials and Advance Engines to Reduce Life Cycle Energy and Greenhouse Gas Emissions for ICVs and Evs Using Design Harmonization Techniques. [Doctoral Dissertation]. University of Michigan; 2013. Available from: http://hdl.handle.net/2027.42/102298

28. Vaughan, Adam. Adaptive Machine Learning for Modeling and Control of Non-Stationary, Near Chaotic Combustion in Real-Time.

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

URL: http://hdl.handle.net/2027.42/111333

► Fuel efficient Homogeneous Charge Compression Ignition (HCCI) engine combustion phasing predictions must contend with non-linear chemistry, non-linear physics, near chaotic period doubling bifurcation(s), turbulent mixing,… (more)

▼ Fuel efficient Homogeneous Charge Compression Ignition (HCCI) engine combustion phasing predictions must contend with non-linear chemistry, non-linear physics, near chaotic period doubling bifurcation(s), turbulent mixing, model parameters that can drift day-to-day, and air-fuel mixture state information that cannot typically be resolved on a cycle-to-cycle basis, especially during transients. Unlike many contemporary modeling approaches, this work does not attempt to solve for the myriad of combustion processes that are in practice unobservable in a metal engine. Instead, this work treads closely to physically measurable quantities within the framework of an abstract discrete dynamical system that is explicitly designed to capture many known combustion relationships, without ever explicitly solving for them. This abstract dynamical system is realized with an Extreme Learning Machine (ELM) that is extended to adapt to the combustion process from cycle-to-cycle with a new Weighted Ring-ELM algorithm. Combined, the above techniques are shown to provide unprecedented cycle-to-cycle predictive capability during transients, near chaotic combustion, and at steady-state, right up to complete misfire. These predictions only require adding an in-cylinder pressure sensor to production engines, which could cost as little as $13 per cylinder. By design, the framework is computationally efficient, and the approach is shown to predict combustion in sub-millisecond real-time using only an iPhone generation 1 processor (the $35 Raspberry Pi). This is in stark contrast to supercomputer approaches that model down to the minutiae of individual reactions but have yet to demonstrate such fidelity against cycle-to-cycle experiments. Finally, the feasibility of cycle-to-cycle model predictive control with this real-time framework is demonstrated. Advisors/Committee Members: Bohac, Stani V. (committee member), Borgnakke, Claus (committee member), Scott, Clayton D. (committee member), Boehman, Andre L. (committee member), Assanis, Dennis N. (committee member), Hoard, John W. (committee member).

Subjects/Keywords: Real-time Adaptive Neural Network; Weighted Ring - Extreme Learning Machine; Engine Combustion Cyclic Variability; Nonlinear Model Predictive Control; Dynamical Systems; Chaos Theory; Mechanical Engineering; Engineering

…approximations. . . 30 31 Two experimental test cells at the University of Michigan…

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APA (6^th Edition):

Vaughan, A. (2015). Adaptive Machine Learning for Modeling and Control of Non-Stationary, Near Chaotic Combustion in Real-Time. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/111333

Chicago Manual of Style (16^th Edition):

Vaughan, Adam. “Adaptive Machine Learning for Modeling and Control of Non-Stationary, Near Chaotic Combustion in Real-Time.” 2015. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/111333.

MLA Handbook (7^th Edition):

Vaughan, Adam. “Adaptive Machine Learning for Modeling and Control of Non-Stationary, Near Chaotic Combustion in Real-Time.” 2015. Web. 07 Mar 2021.

Vancouver:

Vaughan A. Adaptive Machine Learning for Modeling and Control of Non-Stationary, Near Chaotic Combustion in Real-Time. [Internet] [Doctoral dissertation]. University of Michigan; 2015. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/111333.

Council of Science Editors:

Vaughan A. Adaptive Machine Learning for Modeling and Control of Non-Stationary, Near Chaotic Combustion in Real-Time. [Doctoral Dissertation]. University of Michigan; 2015. Available from: http://hdl.handle.net/2027.42/111333

University of Michigan

29. Kang, Youngjae. Surface Scaling Mechanism and Prediction for Concrete.

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

URL: http://hdl.handle.net/2027.42/75926

► Severe deterioration of concrete joints has developed at a rapid rate for several Michigan highway projects. This deterioration was found to be linked to deicer… (more)

▼ Severe deterioration of concrete joints has developed at a rapid rate for several Michigan highway projects. This deterioration was found to be linked to deicer salt applications during the winter season. Surface scaling was found to be associated with frost deterioration of the portland cement mortar from exposure to a salt solution on the surface during a freeze-thaw cycle. These concretes were found to have inadequate entrained air content in the Portland cement paste. The driving force responsible for developing surface scaling can be explained by means of an existing theory known as the Cryogenic Suction Pump. This mechanism is thermodynamic-based. For pure surface water the cryogenic pump is limited to capillary pore-suction, as the surface liquid freezes instantly. When deicing chemicals are present on the surface the salt solution mixture remains unfrozen and thus increases the suction pump effect. Entrained air was found to be the major factor in mitigating the cryogenic suction pump. Cryogenic pump expansion is reduced with increasing entrained air content as air decreases pore-filling and creates capillary discontinuity, which inhibits suction. This study is a first to identify a link between surface scaling due to pure water and salt-water (i.e. 3 % sodium chloride concentration). Also, a link between surface scaling and the Interfacial Transit Zone (ITZ) which is a localized zone around the aggregate consisting of higher porosity was found. Due to the larger pore-size and high porosity damage from cryogenic pump initiates in this region. Scaling is localized and propagates with depth and width. Substantial improvement is surface scaling resistance was achieved by eliminating the weak-ITZ by means of pozzolanic reactions between the Portland cement paste and GGBFS. The pozzolanic reactions further reduced capillary sorptivity (i.e. rate of capillary suction versus square root of time) as seen from water sorption results and thus reduces the rate of transport by cryogenic pump. Advisors/Committee Members: Hansen, Will (committee member), Borgnakke, Claus (committee member), Kamat, Vineet Rajendra (committee member), Pan, Jwo (committee member).

Subjects/Keywords: Surface Scaling; Cryogenic Suction Pump; Civil and Environmental Engineering; Engineering

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APA (6^th Edition):

Kang, Y. (2010). Surface Scaling Mechanism and Prediction for Concrete. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/75926

Chicago Manual of Style (16^th Edition):

Kang, Youngjae. “Surface Scaling Mechanism and Prediction for Concrete.” 2010. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/75926.

MLA Handbook (7^th Edition):

Kang, Youngjae. “Surface Scaling Mechanism and Prediction for Concrete.” 2010. Web. 07 Mar 2021.

Vancouver:

Kang Y. Surface Scaling Mechanism and Prediction for Concrete. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/75926.

Council of Science Editors:

Kang Y. Surface Scaling Mechanism and Prediction for Concrete. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/75926

University of Michigan

30. Chen, Yong-Song. A Segmented Model for Studying Water Transport in a PEM Fuel Cell.

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

URL: http://hdl.handle.net/2027.42/62326

► Fuel Cells are devices that generate electricity by electrochemically combining hydrogen and oxygen. Water management plays an important role in the durability and efficiency of… (more)

▼ Fuel Cells are devices that generate electricity by electrochemically combining hydrogen and oxygen. Water management plays an important role in the durability and efficiency of a proton exchange membrane fuel cell (PEMFC). In this study, single cells are modeled as lumped models consisting of 15 interconnected segments, which are linked according to the flow field patterns of the anode and cathode but they are treated as individual lumped elements. Parameters of this model were calibrated based on neutron radiography experimental results obtained at the NIST Center for Neutron Research (NCNR). Three special single cells were designed for the purpose of detecting liquid water and water vapor simultaneously. The major difference between our design and traditional flow field designs is the fact the anode channels and cathode channels were shifted sideways, so that the anode and cathode channels do not overlap in the majority of the active areas. The liquid water is measured by using neutron radiography. The water vapor is measured by the twenty relative humidity sensors embedded in the anode and the cathode flow field plates. The effects of relative humidity and stoichiometry of cathode inlet on relative humidity distribution in the channels and on water accumulation in the GDLs were investigated in this study. The liquid water accumulation at steady-state was calculated by using imaging mask techniques and least-squares method. It is demonstrated that liquid water tends to accumulates in the gas diffusion layers under the rib. Modeling results suggest that opposite flow direction improve the cell performance at low humidity conditions. Accordingly, this segmented model is useful in designing flow field patterns and comparing the influence of different flow field patterns before they are machined on the flow field plates. That reduces the cost of developing and designing a fuel cell. Advisors/Committee Members: Peng, Huei (committee member), Borgnakke, Claus (committee member), Sun, Jing (committee member), Thompson Jr, Levi T. (committee member).

Subjects/Keywords: Fuel Cell; Neutron Radiography; Water Management; Model; Humidity; Mechanical Engineering; Engineering

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

APA (6^th Edition):

Chen, Y. (2009). A Segmented Model for Studying Water Transport in a PEM Fuel Cell. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/62326

Chicago Manual of Style (16^th Edition):

Chen, Yong-Song. “A Segmented Model for Studying Water Transport in a PEM Fuel Cell.” 2009. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/62326.

MLA Handbook (7^th Edition):

Chen, Yong-Song. “A Segmented Model for Studying Water Transport in a PEM Fuel Cell.” 2009. Web. 07 Mar 2021.

Vancouver:

Chen Y. A Segmented Model for Studying Water Transport in a PEM Fuel Cell. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/62326.

Council of Science Editors:

Chen Y. A Segmented Model for Studying Water Transport in a PEM Fuel Cell. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/62326

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