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You searched for +publisher:"University of Michigan" +contributor:("Middleton, Robert John"). Showing records 1 – 2 of 2 total matches.

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University of Michigan

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

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

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

APA (6th 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 (16th Edition):

Martin, Jonathan. “Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine.” 2019. Doctoral Dissertation, University of Michigan. Accessed February 27, 2021. http://hdl.handle.net/2027.42/153383.

MLA Handbook (7th Edition):

Martin, Jonathan. “Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine.” 2019. Web. 27 Feb 2021.

Vancouver:

Martin J. Exploring the Combustion Modes of A Dual-Fuel Compression Ignition Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Feb 27]. 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

2. Kiwan, Rani. On the Estimation of Exhaust Gas Recirculation Flow and Waste Heat Recovery Tradeoffs Based on Differential Pressure Measurements.

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

Both exhaust gas recirculation (EGR) and waste heat recovery (WHR) are attractive technologies for more efficient spark ignition (SI) engines. The fuel economy benefit of cooled external EGR on SI engines is well established, and preliminary first law analysis of engine energy flows indicates the large potential for efficiency improvements with WHR. Nevertheless, both technologies face major challenges that need to be addressed to become viable solutions for more efficient SI engines. Cooled external EGR improves SI engine efficiency under wide range of conditions. However, inaccurate estimation of the EGR fraction in the intake manifold can be detrimental as it can lead to inaccurate air charge estimation, knock and misfire. Accurate EGR estimation based on a differential pressure (ΔP) measurement is very challenging at the low ΔP 's due to pressure pulsations and inertial effects. While some systems are capable of increasing ΔP across the EGR valve to improve EGR estimation, the higher ΔP is undesirable as it can increase pumping losses. EGR estimation accuracy at low ΔP can be improved by fast sampling of the ΔP signal and using the newly derived approximations of the unsteady compressible flow orifice equation. Both experimental data from a modified Ford 1.6 L EcoBoost engine with added LP and HP-EGR loops, and simulation predictions from its GT-Power models are used to evaluate the estimation methods. A sampling frequency of at least 1 kHz reduces the ΔP lower bound required to keep the LP and HP-EGR estimation error within a target 1% from 12.7 and 27.9 to 1.9 and 2.9 kPa respectively. The LP ΔP lower bound can be further reduced to 1.1 kPa with variable filtering, but the sampling frequency requirement is increased to 3 kHz to achieve the full benefit. The impact of gauge-line distortions and EGR valve area offset errors are also evaluated. An extension of a preexisting lumped parameter model is proposed to estimate the actual ΔP from the distorted measurement. Simulation results show that the proposed model can correct for the gauge-line errors under modeled pressure measurement noise. Valve area offset errors are shown to have substantial impact on the EGR estimation error especially for the HP-EGR case. A novel online calibration method for the HP-EGR valve area using preexisting engine sensors is developed and shown to have promise for implementation. The second part of this thesis studies the limitations and challenges of WHR through electric turbo-generation. Insights into the tradeoffs between exhaust energy recovery and increased pumping losses from the flow restriction of the electric turbo-generator (eTG) are provided and assessed using thermodynamic principles and with a detailed GT-Power engine model. The additional pumping losses are load independent and cannot be offset by the eTG power at low loads. Engine simulations are used to predict the influence of the increased back pressure on pumping work, in-cylinder residuals and combustion. The eTG is detrimental at the high loads as it requires… Advisors/Committee Members: Stefanopoulou, Anna G (committee member), Hofmann, Heath (committee member), Boehman, Andre L (committee member), Middleton, Robert John (committee member).

Subjects/Keywords: Estimation of Exhaust Gas Recirculation Flow based on Pressure Measurements; Waste Heat Recovery Tradeoffs; Mechanical Engineering; Engineering

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

APA (6th Edition):

Kiwan, R. (2019). On the Estimation of Exhaust Gas Recirculation Flow and Waste Heat Recovery Tradeoffs Based on Differential Pressure Measurements. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/151426

Chicago Manual of Style (16th Edition):

Kiwan, Rani. “On the Estimation of Exhaust Gas Recirculation Flow and Waste Heat Recovery Tradeoffs Based on Differential Pressure Measurements.” 2019. Doctoral Dissertation, University of Michigan. Accessed February 27, 2021. http://hdl.handle.net/2027.42/151426.

MLA Handbook (7th Edition):

Kiwan, Rani. “On the Estimation of Exhaust Gas Recirculation Flow and Waste Heat Recovery Tradeoffs Based on Differential Pressure Measurements.” 2019. Web. 27 Feb 2021.

Vancouver:

Kiwan R. On the Estimation of Exhaust Gas Recirculation Flow and Waste Heat Recovery Tradeoffs Based on Differential Pressure Measurements. [Internet] [Doctoral dissertation]. University of Michigan; 2019. [cited 2021 Feb 27]. Available from: http://hdl.handle.net/2027.42/151426.

Council of Science Editors:

Kiwan R. On the Estimation of Exhaust Gas Recirculation Flow and Waste Heat Recovery Tradeoffs Based on Differential Pressure Measurements. [Doctoral Dissertation]. University of Michigan; 2019. Available from: http://hdl.handle.net/2027.42/151426

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