In-cylinder fuel reforming for small-scale mixed combustion/electrochemical engines
Abstract/Contents
- Abstract
- Previous efforts towards increasing the efficiency of piston engine-based systems have been limited in their ability to surpass 60% efficiency on an exergy basis due to the significant exergy destruction associated with combustion. This thesis assesses the prospects of achieving efficiencies in excess of 60% on an exergy basis, and approaching 70% on an LHV basis, through the use of a combined combustion/electrochemical strategy. The proposed strategy utilizes an engine upstream of a fuel cell to provide a combined fuel-reforming and work-producing function in the overall system. The products of rich combustion are then fed downstream, through an additional catalytic reforming step, to a fuel cell for further oxidation. The assessment of the proposed strategy occurs in two major areas. The first focuses on the development of detailed computational models of the major devices in the proposed mixed combustion/electrochemical system architectures. These device models are then used in overall system models to determine if the proposed architectures are able to successfully reduce the overall reaction-related losses. Once a viable system is identified, the focus shifts to addressing the ability of the engine to perform its intended function in the overall system. In the chosen system, the engine must operate at very rich equivalence ratios in an insulated in-cylinder environment that requires a direct-injection, compression-ignition (DI/CI) combustion strategy. To achieve the desired equivalence ratios, without generating large quantities of soot, ethanol and methanol are investigated as the primary fuels for the system. Both fuels have shown promise in their ability to remain below current regulation limits in terms of engine-out soot emissions at stoichiometric equivalence ratios, but the rich-combustion regime has been largely unexplored. This work investigates the rich DI/CI combustion regime in three avenues. The first focuses on performing equivalence ratio sweeps for both fuels of interest on a research engine that approximates the in-cylinder environment of the insulated engine in the combined system. The second involves conducting optical access experiments that attempt to gain more insight into the driving factors that dictate the performance measured in the first. The final step incorporates the findings from the optical access experiments into a phenomenological DI/CI combustion model designed to represent the relevant physical processes in this regime. Ultimately, the results of the computational model are compared to the measured experimental results in an effort to better understand the observed trends.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2018; ©2018 |
| Publication date | 2018; 2018 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Donohue, Mark Andrew |
|---|---|
| Degree supervisor | Edwards, C. F. (Christopher Francis) |
| Thesis advisor | Edwards, C. F. (Christopher Francis) |
| Thesis advisor | Lutz, Andrew E. (Andrew Edward) |
| Thesis advisor | Mitchell, Reginald |
| Degree committee member | Lutz, Andrew E. (Andrew Edward) |
| Degree committee member | Mitchell, Reginald |
| Associated with | Stanford University, Department of Mechanical Engineering. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Mark Andrew Donohue. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2018. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2018 by Mark Andrew Donohue
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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