+publisher:"University of Michigan" +contributor:("Lavoie, George")

University of Michigan

1. Han, Tae Hoon. Strategies to Improve Efficiency and Emissions in Spark Ignition Engines.

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

URL: http://hdl.handle.net/2027.42/153471

► This dissertation investigates the knock mitigation strategies and their experimental validation for improving performance and emissions with three different engine parameters: (i)Fuels (oxygenated fuel gasoline… (more)

▼ This dissertation investigates the knock mitigation strategies and their experimental validation for improving performance and emissions with three different engine parameters: (i)Fuels (oxygenated fuel gasoline blends and syngas addition); (ii)Mixture dilution (EGR and Lean dilution); (iii)Injection strategies (DI and PFI combined dual fuel injection and multiple injections). Besides, a newly discovered unique relation between knocking and particulate matter emissions is examined in the last part with several conceptual models for better understanding of this phenomenon. The first part of this dissertation is about the effects of three oxygenated fuels (2,5-dimethylfuran, ethanol, and isobutanol) blended in gasoline on engine combustion, knock, and particulate matter emissions. One of the most promising furan functional group fuels, 2,5-dimethylfuran, is experimentally compared with two common alcohol-type oxygenates, ethanol and iso-butanol. Three major parameters are varied for the examination of oxygenates: fuel type, blend ratio, and boost level. The results show that the 2,5-dimethylfuran blends have the ability to extend knock limits as much as ethanol, but with relatively higher particulate matter emissions. As a second fuel study, syngas (hydrogen and carbon monoxide) aided engine combustion is experimentally investigated under EGR diluted and lean conditions by focusing on knock propensity, thermal efficiency, and emissions. Knocking tendencies are analyzed, and the thermal efficiency and emissions difference are discussed as well. The results show that with increasing the syngas addition, knocking is strongly suppressed, and the effect is more beneficial with EGR dilution than with air dilution. For the study of fuel injection strategies, two concepts of injection strategies are introduced and experimentally investigated. The first injection strategy is combined direct and port fuel injection to extend knock and EGR dilution limits using gasoline and ethanol fuels. The results showed that dual injection was beneficial to shorten the burn duration and improve combustion stability, but dual injection is slightly more sensitive to knock than direct injection primarily due to increased unburned gas temperature. The particulate matter emissions from dual injection were slightly lower, and the gaseous emissions showed lower total hydrocarbons and similar nitrogen oxides compared with only using direct injection of E20 fuel. The second fuel injection strategy involves multiple direct injections, which inject fuel multiple times in a cycle. This study explores the effect of multiple injections on knock, engine performance, particulate matter, and gaseous emissions. Two aspects of multiple injection strategies were experimentally investigated: the number of injections and the timing of the injections. The results confirm that multiple injection maintains torque and combustion stability but increases knock limits and thermal efficiency due to improved heat release phasing. The gaseous pollutant emissions including… Advisors/Committee Members: Boehman, Andre L (committee member), Raman, Venkatramanan (committee member), Lavoie, George A (committee member), Wooldridge, Margaret S (committee member).

Subjects/Keywords: Knock limit extension; Particulate matter emissions; Exhaust Gas Recirculation (EGR); Alternative fuels; Injection strategies; Spark ignition (SI) engine; Mechanical Engineering; Engineering

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APA (6^th Edition):

Han, T. H. (2019). Strategies to Improve Efficiency and Emissions in Spark Ignition Engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/153471

Chicago Manual of Style (16^th Edition):

Han, Tae Hoon. “Strategies to Improve Efficiency and Emissions in Spark Ignition Engines.” 2019. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/153471.

MLA Handbook (7^th Edition):

Han, Tae Hoon. “Strategies to Improve Efficiency and Emissions in Spark Ignition Engines.” 2019. Web. 13 Apr 2021.

Vancouver:

Han TH. Strategies to Improve Efficiency and Emissions in Spark Ignition Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/153471.

Council of Science Editors:

Han TH. Strategies to Improve Efficiency and Emissions in Spark Ignition Engines. [Doctoral Dissertation]. University of Michigan; 2019. Available from: http://hdl.handle.net/2027.42/153471

University of Michigan

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

APA (6^th Edition):

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

Chicago Manual of Style (16^th Edition):

Ortiz-Soto, Elliott Alexander. “Combustion Modeling of Spark Assisted Compression Ignition for Experimental Analysis and Engine System Simulations.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 13, 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. 13 Apr 2021.

Vancouver:

Ortiz-Soto EA. Combustion Modeling of Spark Assisted Compression Ignition for Experimental Analysis and Engine System Simulations. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 13]. 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

3. Martin, Jonathan. Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine.

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

URL: http://hdl.handle.net/2027.42/153383

► Compression-ignition (CI) engines, also known as “diesel” engines, can produce higher thermal efficiency (TE) than spark-ignition (SI) engines, which allows them to emit less carbon… (more)

▼ Compression-ignition (CI) engines, also known as “diesel” engines, can produce higher thermal efficiency (TE) than spark-ignition (SI) engines, which allows them to emit less carbon dioxide (CO2) per unit of energy generated. Unfortunately, in practice the TE of CI engines is limited by the need to maintain sufficiently low emissions of nitrogen oxides (NOx) and soot. This problem can be mitigated by operating CI engines in dual-fuel modes with port fuel injection (PFI) of gasoline supplementing the direct injection (DI) of diesel fuel. Several strategies for doing this have been introduced in recent years, but these operating modes are usually studied individually at discrete conditions. This thesis introduces a classification system for dual-fuel CI modes that links together several previously studied modes across a continuous two-dimensional diagram. The combustion modes covered by this system include the standard modes of conventional diesel combustion (CDC) and conventional dual-fuel (CDF); the well-explored advanced combustion modes of HCCI, RCCI, PCCI, and PPCI; and a relatively unexplored combustion mode that is herein titled “Piston-split Dual-Fuel Combustion” or PDFC. The results show that dual-fuel CI engines can simultaneously increase TE and lower NOx and/or soot emissions at high loads through the use of Partial HCCI (PHCCI), despite an increase in emissions of carbon monoxide (CO) and unburnt hydrocarbons (UHC). At low loads, PHCCI is not possible, but either PDFC or RCCI can be used to further improve NOx and/or soot emissions, albeit at slightly lower TE and still higher emissions of CO and UHC. This multi-mode strategy of PHCCI at high loads and PDFC or RCCI at low loads is particularly useful when low engine-out NOx emissions are required. Advisors/Committee Members: Boehman, Andre L (committee member), Lastoskie, Christian M (committee member), Lavoie, George A (committee member), Middleton, Robert John (committee member), Wooldridge, Margaret S (committee member).

Subjects/Keywords: compression-ignition engines; dual-fuel combustion; advanced combustion modes; RCCI; HCCI; thermal efficiency; Mechanical Engineering; Engineering

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APA (6^th Edition):

Martin, J. (2019). Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/153383

Chicago Manual of Style (16^th Edition):

Martin, Jonathan. “Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine.” 2019. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/153383.

MLA Handbook (7^th Edition):

Martin, Jonathan. “Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine.” 2019. Web. 13 Apr 2021.

Vancouver:

Martin J. Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/153383.

Council of Science Editors:

Martin J. Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine. [Doctoral Dissertation]. University of Michigan; 2019. Available from: http://hdl.handle.net/2027.42/153383

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

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

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

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

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

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

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APA (6^th Edition):

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

Chicago Manual of Style (16^th Edition):

Middleton, Robert John. “Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/107052.

MLA Handbook (7^th Edition):

Middleton, Robert John. “Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions.” 2014. Web. 13 Apr 2021.

Vancouver:

Middleton RJ. Simulation of Spark Assisted Compression Ignition Combustion Under EGR Dilute Engine Operating Conditions. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/107052.

Council of Science Editors:

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

5. 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 April 13, 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. 13 Apr 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 Apr 13]. 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

6. Fatouraie, Mohammad. The Effects of Ethanol/Gasoline Blends on Advanced Combustion Strategies in Internal Combustion Engines.

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

URL: http://hdl.handle.net/2027.42/107175

► This dissertation presents the effects of blending ethanol with gasoline on advanced combustion strategies in internal combustion engines. The unique chemical, physical and thermal properties… (more)

▼ This dissertation presents the effects of blending ethanol with gasoline on advanced combustion strategies in internal combustion engines. The unique chemical, physical and thermal properties of ethanol/ gasoline blends can be used to improve the performance and emissions of advanced engine technologies like gasoline direct injection (GDI) also called direct injection spark ignition (DISI), homogenous charge compression ignition (HCCI) and spark assisted homogenous charge compression ignition (SA-HCCI). This work used experimental studies to understand the impact of ethanol and ethanol/gasoline blends on advanced engine strategies and on understanding which of the fundamental properties of ethanol and ethanol blends control engine performance. The technical approach leveraged high speed imaging to study the fuel spray, combustion, ignition, and sooting (where appropriate) properties of the fuels using different optically accessible engine hardware, including HCCI and GDI configurations. The results of the HCCI work indicated stable operating conditions could be extended to leaner mixtures using the ethanol blends, if the effect of charge cooling due to fuel vaporization was anticipated. Ethanol also improved the stability of flame initiation and growth in SA-HCCI, which affected the global autoignition and performance of the engine. The effect of ethanol on these chemically-controlled engine modes was dominated by the impact of the fuel on thermal stratification. Ethanol combustion chemistry appeared to have little impact. Significant reduction in soot formation was observed in the DISI engine studies using ethanol blends compared to a baseline of reference grade gasoline. This was due to combined effects of ethanol on combustion chemistry, where oxygenated fuels suppress the formation of soot precursors, and of ethanol on increasing evaporation and reducing liquid fuel on the piston, where ethanol changed the fuel spray cone angle and spray collapse. In particular, fuel impingement and wetting of the piston surface dominated in-cylinder soot formation, thus the ethanol fuel spray characteristics that reduced interaction of the fuel spray with the piston and enhanced fuel mixing led to less soot formation. Advisors/Committee Members: Wooldridge, Margaret S. (committee member), Kolmanovsky, Ilya Vladimir (committee member), Wooldridge, Steven T. (committee member), Lavoie, George A. (committee member), Boehman, Andre L. (committee member).

Subjects/Keywords: HCCI; ETHANOL; DISI; SOOT; PM; SACI; Mechanical Engineering; Engineering

…33], [34]. At the University of Michigan, Zigler et al. have contributed to… …emission characteristics were performed using two optical engine facilities at the University of… …Michigan. The kinetically controlled combustion studies were performed using a port fuel…

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APA (6^th Edition):

Fatouraie, M. (2014). The Effects of Ethanol/Gasoline Blends on Advanced Combustion Strategies in Internal Combustion Engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/107175

Chicago Manual of Style (16^th Edition):

Fatouraie, Mohammad. “The Effects of Ethanol/Gasoline Blends on Advanced Combustion Strategies in Internal Combustion Engines.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/107175.

MLA Handbook (7^th Edition):

Fatouraie, Mohammad. “The Effects of Ethanol/Gasoline Blends on Advanced Combustion Strategies in Internal Combustion Engines.” 2014. Web. 13 Apr 2021.

Vancouver:

Fatouraie M. The Effects of Ethanol/Gasoline Blends on Advanced Combustion Strategies in Internal Combustion Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/107175.

Council of Science Editors:

Fatouraie M. The Effects of Ethanol/Gasoline Blends on Advanced Combustion Strategies in Internal Combustion Engines. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/107175

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

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

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

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

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

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

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APA (6^th Edition):

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

Chicago Manual of Style (16^th Edition):

Park, Hee Jun. “Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers.” 2009. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/62428.

MLA Handbook (7^th Edition):

Park, Hee Jun. “Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers.” 2009. Web. 13 Apr 2021.

Vancouver:

Park HJ. Development of an In-cylinder Heat Transfer Model with Variable Density Effects on Thermal Boundary Layers. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/62428.

Council of Science Editors:

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

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

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

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

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

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

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

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APA (6^th Edition):

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

Chicago Manual of Style (16^th Edition):

Mamalis, Sotirios. “Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines.” 2012. Doctoral Dissertation, University of Michigan. Accessed April 13, 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. 13 Apr 2021.

Vancouver:

Mamalis S. Simulation and Thermodynamic Analysis of High Pressure Lean Burn Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2012. [cited 2021 Apr 13]. 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

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

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

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

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

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

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

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APA (6^th Edition):

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

Chicago Manual of Style (16^th Edition):

Olesky, Laura Katherine. “An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap.” 2013. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/99979.

MLA Handbook (7^th Edition):

Olesky, Laura Katherine. “An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap.” 2013. Web. 13 Apr 2021.

Vancouver:

Olesky LK. An Experimental Investigation of the Burn Rates of Naturally Aspirated Spark Assisted Compression Ignition Combustion in a Single Cylinder Engine with Negative Valve Overlap. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/99979.

Council of Science Editors:

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

10. 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 April 13, 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. 13 Apr 2021.

Vancouver:

Kodavasal J. Effect of Charge Preparation Strategy on HCCI Combustion. [Internet] [Doctoral dissertation]. University of Michigan; 2013. [cited 2021 Apr 13]. 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

11. Klinkert, Stefan. An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap.

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

URL: http://hdl.handle.net/2027.42/107167

► Use of homogeneous charge compression ignition (HCCI) combustion mode in engines offers the potential to simultaneously achieve high efficiency and low emissions. Implementation and practical… (more)

▼ Use of homogeneous charge compression ignition (HCCI) combustion mode in engines offers the potential to simultaneously achieve high efficiency and low emissions. Implementation and practical use of HCCI combustion, however, remain a challenge due to the limited operating load range. Most studies on high load extension of HCCI have been done on engines with conventional positive valve overlap (PVO) strategies, which use a heater to control intake temperature and adjust combustion timing. Although there has been work on engines employing a more practical negative valve overlap (NVO) strategy, which controls charge temperature by varying the retained amount of hot internal residual gas, most of these studies were confined to a limited boost pressure range and/ or did not explore and isolate the effects of individual thermo-physical parameters on combustion and the maximum load limit. This research work is unique in that a practical yet highly flexible NVO engine, allowing for independent control of intake boost pressure, charge temperature and composition, thermal/ compositional stratification (NVO) and exhaust back-pressure, was used to independently investigate the effects of these variables on burn duration and combustion phasing limits. Results showed that maximum achievable loads for the NVO engine were less than those obtained by previous workers on a boosted PVO engine due to less efficient breathing, less stable combustion, which limits the achievable combustion phasing retard, and lower maximum allowable peak cylinder pressure. This research provides new insights into how boost pressure and other operating parameters in a NVO HCCI engine impact the maximum attainable load and combustion phasing limits. The results suggest that the maximum load is more dependent on the combustion stability limit and overall engine constraints, such as maximum allowable peak cylinder pressure and limited cam-phasing authority, than on burn rates. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Sick, Volker (committee member), Driscoll, James F. (committee member), Bohac, Stani V. (committee member), Boehman, Andre L. (committee member), Lavoie, George A. (committee member).

Subjects/Keywords: HCCI; Maximum Load Limit; Negative Valve Overlap; Experimental Investigation; Gasoline; Mechanical Engineering; Engineering

…85 Comparison of two fundamentally different boosted HCCI engine setups University of… …Michigan NVO and Sandia National Laboratory PVO . . . . 96 4.1 Experimental conditions during Φ…

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APA (6^th Edition):

Klinkert, S. (2014). An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/107167

Chicago Manual of Style (16^th Edition):

Klinkert, Stefan. “An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/107167.

MLA Handbook (7^th Edition):

Klinkert, Stefan. “An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap.” 2014. Web. 13 Apr 2021.

Vancouver:

Klinkert S. An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/107167.

Council of Science Editors:

Klinkert S. An Experimental Investigation of the Maximum Load Limit of Boosted HCCI Combustion in a Gasoline Engine with Negative Valve Overlap. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/107167

12. 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 April 13, 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. 13 Apr 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 Apr 13]. 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

13. Hagen, Luke Monroe. Experimental Effects of Low Octane Primary Reference Fuels on Burn Rates and Phasing Limits in a Homogeneous Charge Compression Ignition Engine with Negative Valve Overlap.

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

URL: http://hdl.handle.net/2027.42/107064

► Homogeneous charge compression ignition (HCCI) remains an active area of engine research, promising to deliver high thermal efficiency while producing low levels of nitrogen oxides… (more)

▼ Homogeneous charge compression ignition (HCCI) remains an active area of engine research, promising to deliver high thermal efficiency while producing low levels of nitrogen oxides (NOx) and particulate emissions. The pre-mixed auto-ignition nature of HCCI allows the use of a wide variety of fuels, including fuels with lower octane number (ON) than traditional gasoline spark-ignited engines. A method to achieve HCCI traps high levels of internal exhaust gas residuals (iEGR) which introduce thermal and compositional gradients. The contributions in this work compare fuel effects on burn rates and phasing limits of low ON primary reference fuels (PRFs) to gasoline, separating the effects of fuel from iEGR effects. Specifically, in this study, increased load limits were demonstrated for a low ON fuel, but changes in composition obfuscated fuel effects. A new experimental method was therefore developed which isolated composition effects across wide levels of iEGR. Using this method, gasoline at fixed combustion phasing was shown to exhibit sensitivity to increasing iEGR with burn rates decreasing by 15% compared to the lowest iEGR case. Examining the effect of iEGR on stability limits demonstrated iEGR increased cyclic variability due to cyclic feedback. Further experiments showed burn rates of the primary reference fuel PRF40 were 35% faster than gasoline at equal iEGR, but PRF40 showed no dependence on iEGR. PRF40 required a reduced IVC temperature compared to gasoline, which could reduce thermal gradients and increase burn rates. Increased phasing limits were consistently demonstrated for PRF60 compared to gasoline as iEGR was reduced. Both PRF40 and PRF60 demonstrated increasing levels of low temperature heat release (LTHR) as engine speed was reduced, and at 1000 rpm PRF60 showed no phasing dependence on iEGR. Compared to gasoline, observed differences in behavior for the low ON PRFs are attributed to enhanced non-Arrhenius ignition delay behavior which is understood to reduce sensitivity to thermal gradients (or iEGR) and cyclic variations in temperature. The results of this study are the first to isolate charge composition effects during HCCI operation, and the results provide important quantitative insight into the relative importance of thermal stratification and chemical effects of fuels and iEGR. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Wooldridge, Margaret S. (committee member), Driscoll, James F. (committee member), Boehman, Andre L. (committee member), Lavoie, George A. (committee member), Bohac, Stani V. (committee member).

Subjects/Keywords: Homogeneous Charge Compression Ignition; Primary Reference Fuels; Low Octane; Ignition Delay; Thermal Stratification; Burn Rates; Mechanical Engineering; Engineering

…x28;MK) method [37] and Jacob’s work at The University of Michigan [38…

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APA (6^th Edition):

Hagen, L. M. (2014). Experimental Effects of Low Octane Primary Reference Fuels on Burn Rates and Phasing Limits in a Homogeneous Charge Compression Ignition Engine with Negative Valve Overlap. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/107064

Chicago Manual of Style (16^th Edition):

Hagen, Luke Monroe. “Experimental Effects of Low Octane Primary Reference Fuels on Burn Rates and Phasing Limits in a Homogeneous Charge Compression Ignition Engine with Negative Valve Overlap.” 2014. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/107064.

MLA Handbook (7^th Edition):

Hagen, Luke Monroe. “Experimental Effects of Low Octane Primary Reference Fuels on Burn Rates and Phasing Limits in a Homogeneous Charge Compression Ignition Engine with Negative Valve Overlap.” 2014. Web. 13 Apr 2021.

Vancouver:

Hagen LM. Experimental Effects of Low Octane Primary Reference Fuels on Burn Rates and Phasing Limits in a Homogeneous Charge Compression Ignition Engine with Negative Valve Overlap. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/107064.

Council of Science Editors:

Hagen LM. Experimental Effects of Low Octane Primary Reference Fuels on Burn Rates and Phasing Limits in a Homogeneous Charge Compression Ignition Engine with Negative Valve Overlap. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/107064

University of Michigan

14. Mo, Yanbin. HCCI Heat Release Rate and Combustion Efficiency: A Coupled KIVA Multi-Zone Modeling Study.

Degree: PhD, Mechanical Engineering, 2008, University of Michigan

URL: http://hdl.handle.net/2027.42/60734

► Despite of the abundance of HCCI (Homogeneous Charged Compression Ignition) engine experiments, there are several unknown key characteristics, which are difficult to measure with a… (more)

▼ Despite of the abundance of HCCI (Homogeneous Charged Compression Ignition) engine experiments, there are several unknown key characteristics, which are difficult to measure with a conventional test engine setup. First, the cylinder temperature distribution is not readily available from test measurements. Second, the instability and misfire mechanisms can not be easily analyzed by engine testing. Finally, the ability to isolate a particular variable is not always practical in testing. In this thesis, an analytical tool is used to explore HCCI combustion under more controlled conditions. A newly available KIVA-MZ model with a novel mapping scheme between CFD cells and thermodynamic zones, provides a virtual experimental environment to explore the combustion process with respect to various engine operating and design parameters. Nine engine operating and design parameters were investigated with respect to their effects on ignition timing. Equivalence ratio (0.2~0.4), EGR (5%, 20%, and 40%), Load (7~13 mg/cycle), RPM (750~3750), wall temperature (400K, 450K), swirl (0.93, 3.93), compression ratio (12.5, 16), piston geometry (bowl, pancake), and crevice volume (1%, 4%, and 8%) are those nine parameters. The effects of these parameters on combustion efficiency and burning rate were also investigated with controlled ignition timing. Based on the model results of cylinder temperature distribution information, the design parameters were found to influence the temperature distribution more than the operating parameters did. The ignition timing is not an independently controlled variable; however, the CFD results showed that ignition timing is the single most important variable for the whole combustion process. Besides ignition timing, equivalence ratio and engine speed are the second and third most important variables for burning rate. Fast burning rate normally results in higher combustion efficiency, but the peak combustion efficient is mainly determined by the crevice volume. In order to the knowledge from the CFD parametric study results, HCCI combustion correlations were developed. These correlations were implemented into GT-Power, a leading commercial 1D engine simulation software package handing general engine system simulation. This improved GT-Power model is a significant improvement over traditional HCCI engine control models with fixed combustion efficiency and burning duration. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Driscoll, James F. (committee member), Filipi, Zoran (committee member), Lavoie, George (committee member), Wooldridge, Margaret S. (committee member).

Subjects/Keywords: HCCI; KIVA-MZ; Mechanical Engineering; Engineering

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

APA (6^th Edition):

Mo, Y. (2008). HCCI Heat Release Rate and Combustion Efficiency: A Coupled KIVA Multi-Zone Modeling Study. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/60734

Chicago Manual of Style (16^th Edition):

Mo, Yanbin. “HCCI Heat Release Rate and Combustion Efficiency: A Coupled KIVA Multi-Zone Modeling Study.” 2008. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/60734.

MLA Handbook (7^th Edition):

Mo, Yanbin. “HCCI Heat Release Rate and Combustion Efficiency: A Coupled KIVA Multi-Zone Modeling Study.” 2008. Web. 13 Apr 2021.

Vancouver:

Mo Y. HCCI Heat Release Rate and Combustion Efficiency: A Coupled KIVA Multi-Zone Modeling Study. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/60734.

Council of Science Editors:

Mo Y. HCCI Heat Release Rate and Combustion Efficiency: A Coupled KIVA Multi-Zone Modeling Study. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/60734

University of Michigan

15. Martz, Jason Brian. Simulation and Model Development for Auto-Ignition and Reaction Front Propagation in Low-Temperature High-Pressure Lean-Burn Engines.

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

URL: http://hdl.handle.net/2027.42/78870

► While Homogeneous Charge Compression Ignition (HCCI) combustion is capable of highly efficient, ultra-low NOx operation, it lacks direct mechanisms for timing and burn rate control… (more)

▼ While Homogeneous Charge Compression Ignition (HCCI) combustion is capable of highly efficient, ultra-low NOx operation, it lacks direct mechanisms for timing and burn rate control and suffers from marginal power densities. Concepts such as Spark-Assisted Compression Ignition (SACI) combustion have shown the ability to partially address these shortcomings, however detailed SACI models are currently lacking. To address the need for reaction front data within the ultra-dilute, high pressure and preheat temperature SACI regime, laminar premixed reaction front simulations were performed and correlations for burning velocity and front thickness were developed from the resulting dataset. Provided that preheat temperatures were elevated and that burned gas temperatures exceeded 1500 K, moderate burning velocities were observed at equivalence ratios typical of mid and high load HCCI operation. For a given burned gas temperature, burning velocities increased when moving from the SI to the SACI combustion regime, i.e. towards higher dilution and higher pre-heat temperatures. Given the proximity of SACI pre-heat temperatures to the ignition temperature, additional simulations examined the combustion regime, structure and general behavior of the reaction front as it propagated into an auto-igniting end-gas. While significant increases in burning velocity accompanied the transition from deflagrative to chemically dominated combustion, the reaction front contributed minimally to end-gas consumption once end-gas temperatures exceeded 1100 K. A model capable of capturing SI, SACI and HCCI combustion modes was formulated and implemented into KIVA-3V. Using the correlated laminar flame speed data, the model was capable of predicting trend-wise agreement with cylinder pressure and imaging data from an optical SACI engine. The simulated presence of flame surface density suggests that although the simulated reaction fronts are ultra-dilute, they are nevertheless within the flamelet regime during the deflagration portion of SACI combustion. End-gas auto-ignition occurred when the charge compression heating from boundary work and reaction front heat release combined to drive the end-gas to its ignition temperature, providing additional latitude for the execution and control of low temperature combustion processes. Additional simulations were performed to assess the ability of this additional deflagrative combustion mode to enable high efficiency operation with elevated work output relative to HCCI combustion. Advisors/Committee Members: Assanis, Dionissios N. (committee member), Babajimopoulos, Aristotelis (committee member), Driscoll, James F. (committee member), Fiveland, Scott B. (committee member), Lavoie, George (committee member), Wooldridge, Margaret S. (committee member).

Subjects/Keywords: HCCI; Spark Assisted Compression Ignition; Knock; Low Temperature Combustion; Flamelet; Spark Ignited; Mechanical Engineering; Engineering

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APA (6^th Edition):

Martz, J. B. (2010). Simulation and Model Development for Auto-Ignition and Reaction Front Propagation in Low-Temperature High-Pressure Lean-Burn Engines. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/78870

Chicago Manual of Style (16^th Edition):

Martz, Jason Brian. “Simulation and Model Development for Auto-Ignition and Reaction Front Propagation in Low-Temperature High-Pressure Lean-Burn Engines.” 2010. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/78870.

MLA Handbook (7^th Edition):

Martz, Jason Brian. “Simulation and Model Development for Auto-Ignition and Reaction Front Propagation in Low-Temperature High-Pressure Lean-Burn Engines.” 2010. Web. 13 Apr 2021.

Vancouver:

Martz JB. Simulation and Model Development for Auto-Ignition and Reaction Front Propagation in Low-Temperature High-Pressure Lean-Burn Engines. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/78870.

Council of Science Editors:

Martz JB. Simulation and Model Development for Auto-Ignition and Reaction Front Propagation in Low-Temperature High-Pressure Lean-Burn Engines. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/78870

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