Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines
This paper reports on the potential of negative valve overlap for improving the net indicated thermal efficiency of gasoline engines during part load. Three fixed fuel flow rates, resulting in indicated mean effective pressures of up to 6 bar, were investigated. At low load, negative valve overlap (...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
SAE International
2018
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| Online Access: | http://hdl.handle.net/1721.1/116165 https://orcid.org/0000-0002-7044-8156 https://orcid.org/0000-0002-5879-2253 |
| _version_ | 1826205538149466112 |
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| author | Cheng, Wai K Rodriguez, Juan Felipe |
| author2 | Massachusetts Institute of Technology. Department of Mechanical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Mechanical Engineering Cheng, Wai K Rodriguez, Juan Felipe |
| author_sort | Cheng, Wai K |
| collection | MIT |
| description | This paper reports on the potential of negative valve overlap for improving the net indicated thermal efficiency of gasoline engines during part load. Three fixed fuel flow rates, resulting in indicated mean effective pressures of up to 6 bar, were investigated. At low load, negative valve overlap (NVO) significantly reduces the pumping loses during the gas exchange loop, achieving up to 7% improvement in indicated efficiency compared to the baseline. Similar efficiency improvements are achieved by positive valve overlap (PVO), with the disadvantage of worse combustion stability from a higher residual gas fraction. As the load increases, achieving the wide-open throttle limit, the benefits of NVO for reducing the pumping losses diminish, while the blow-down losses from early exhaust valve opening increase.
However, a symmetric NVO strategy combined with a shorter exhaust duration has a higher potential for reduction in part-load fuel consumption, as the exhaust valve opening timing can be optimized to minimize the blow-down losses. |
| first_indexed | 2024-09-23T13:14:44Z |
| format | Article |
| id | mit-1721.1/116165 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T13:14:44Z |
| publishDate | 2018 |
| publisher | SAE International |
| record_format | dspace |
| spelling | mit-1721.1/1161652022-09-28T12:54:46Z Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines Cheng, Wai K Rodriguez, Juan Felipe Massachusetts Institute of Technology. Department of Mechanical Engineering Rodriguez, J. Felipe Cheng, Wai K Rodriguez, Juan Felipe This paper reports on the potential of negative valve overlap for improving the net indicated thermal efficiency of gasoline engines during part load. Three fixed fuel flow rates, resulting in indicated mean effective pressures of up to 6 bar, were investigated. At low load, negative valve overlap (NVO) significantly reduces the pumping loses during the gas exchange loop, achieving up to 7% improvement in indicated efficiency compared to the baseline. Similar efficiency improvements are achieved by positive valve overlap (PVO), with the disadvantage of worse combustion stability from a higher residual gas fraction. As the load increases, achieving the wide-open throttle limit, the benefits of NVO for reducing the pumping losses diminish, while the blow-down losses from early exhaust valve opening increase. However, a symmetric NVO strategy combined with a shorter exhaust duration has a higher potential for reduction in part-load fuel consumption, as the exhaust valve opening timing can be optimized to minimize the blow-down losses. Borg-Warner Corporation Fiat Chrysler Automobiles (Firm) General Motors Corporation 2018-06-06T20:23:18Z 2018-06-06T20:23:18Z 2018-04 Article http://purl.org/eprint/type/JournalArticle 0148-7191 http://hdl.handle.net/1721.1/116165 Rodriguez, J. Felipe, and Wai Cheng. "Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines." WCX: SAE World Congress Experience, 10-12 April, 2018, Detroit, Michigan, SAE International, 2018. https://orcid.org/0000-0002-7044-8156 https://orcid.org/0000-0002-5879-2253 en_US https://doi.org/10.4271/2018-01-0377 SAE Technical Papers Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf SAE International Rodriguez |
| spellingShingle | Cheng, Wai K Rodriguez, Juan Felipe Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines |
| title | Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines |
| title_full | Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines |
| title_fullStr | Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines |
| title_full_unstemmed | Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines |
| title_short | Potential of Negative Valve Overlap for Part Load Efficiency Improvement in Gasoline Engines |
| title_sort | potential of negative valve overlap for part load efficiency improvement in gasoline engines |
| url | http://hdl.handle.net/1721.1/116165 https://orcid.org/0000-0002-7044-8156 https://orcid.org/0000-0002-5879-2253 |
| work_keys_str_mv | AT chengwaik potentialofnegativevalveoverlapforpartloadefficiencyimprovementingasolineengines AT rodriguezjuanfelipe potentialofnegativevalveoverlapforpartloadefficiencyimprovementingasolineengines |