Asymmetric inlet valve opening to reduce NOx and soot from a High-Speed Light-Duty Diesel Engine
<p>Swirl flaps are commonly used in modern diesel engines to compensate for low in-cylinder air motion at low engine speeds and increase incylinder swirl. Increasing the air motion improves fuel-air mixing and leads to lower smoke and CO emissions; however the improved mixing leads to shorter...
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| Format: | Conference item |
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Societe Des Ingenieurs de L'Automobile
2018
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| _version_ | 1826272046708948992 |
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| author | Leach, F Davy, M Cooper, B |
| author_facet | Leach, F Davy, M Cooper, B |
| author_sort | Leach, F |
| collection | OXFORD |
| description | <p>Swirl flaps are commonly used in modern diesel engines to compensate for low in-cylinder air motion at low engine speeds and increase incylinder swirl. Increasing the air motion improves fuel-air mixing and leads to lower smoke and CO emissions; however the improved mixing leads to shorter combustion durations and hence a rise in incylinder temperatures. Such a temperature increase can lead to higher NOx emissions when the swirl flap is used (for a given smoke level) – EGR rates can be increased to compensate. Late inlet valve closure can also be used at part load to reduce an engine’s effective compression ratio, and hence in cylinder temperatures and NOx emissions</p><p> In this paper a technique combining these two effects is compared to a standard swirl flap operation. Retarding the closure of only one inlet valve (in this case the helical or flow port) by either 30 or 60 crank angle degrees (CAD) using an offset cam is compared to the use of a swirl flap at a position to give similar in-cylinder swirl levels. EGR swings are conducted at three engine operating points and these effects on emissions, combustion, and fuel consumption explored.</p><p> In this work, experimental results, combined with CFD simulations have been used to understand the effect that asymmetric inlet valve opening is having. The results show that asymmetric inlet valve opening reduces NOx emissions at certain engine operating points without adverse effects on other emissions. The high swirl levels, combined with a reduced effective compression ratio that this technique uses can simultaneously reduce NOx and soot emissions at some part load conditions.</p> |
| first_indexed | 2024-03-06T22:06:22Z |
| format | Conference item |
| id | oxford-uuid:504af8b7-5e08-49e5-8fe7-0ed4c0f507a6 |
| institution | University of Oxford |
| last_indexed | 2024-03-06T22:06:22Z |
| publishDate | 2018 |
| publisher | Societe Des Ingenieurs de L'Automobile |
| record_format | dspace |
| spelling | oxford-uuid:504af8b7-5e08-49e5-8fe7-0ed4c0f507a62022-03-26T16:12:42ZAsymmetric inlet valve opening to reduce NOx and soot from a High-Speed Light-Duty Diesel EngineConference itemhttp://purl.org/coar/resource_type/c_5794uuid:504af8b7-5e08-49e5-8fe7-0ed4c0f507a6Symplectic Elements at OxfordSociete Des Ingenieurs de L'Automobile2018Leach, FDavy, MCooper, B<p>Swirl flaps are commonly used in modern diesel engines to compensate for low in-cylinder air motion at low engine speeds and increase incylinder swirl. Increasing the air motion improves fuel-air mixing and leads to lower smoke and CO emissions; however the improved mixing leads to shorter combustion durations and hence a rise in incylinder temperatures. Such a temperature increase can lead to higher NOx emissions when the swirl flap is used (for a given smoke level) – EGR rates can be increased to compensate. Late inlet valve closure can also be used at part load to reduce an engine’s effective compression ratio, and hence in cylinder temperatures and NOx emissions</p><p> In this paper a technique combining these two effects is compared to a standard swirl flap operation. Retarding the closure of only one inlet valve (in this case the helical or flow port) by either 30 or 60 crank angle degrees (CAD) using an offset cam is compared to the use of a swirl flap at a position to give similar in-cylinder swirl levels. EGR swings are conducted at three engine operating points and these effects on emissions, combustion, and fuel consumption explored.</p><p> In this work, experimental results, combined with CFD simulations have been used to understand the effect that asymmetric inlet valve opening is having. The results show that asymmetric inlet valve opening reduces NOx emissions at certain engine operating points without adverse effects on other emissions. The high swirl levels, combined with a reduced effective compression ratio that this technique uses can simultaneously reduce NOx and soot emissions at some part load conditions.</p> |
| spellingShingle | Leach, F Davy, M Cooper, B Asymmetric inlet valve opening to reduce NOx and soot from a High-Speed Light-Duty Diesel Engine |
| title | Asymmetric inlet valve opening to reduce NOx and soot from a High-Speed Light-Duty Diesel Engine |
| title_full | Asymmetric inlet valve opening to reduce NOx and soot from a High-Speed Light-Duty Diesel Engine |
| title_fullStr | Asymmetric inlet valve opening to reduce NOx and soot from a High-Speed Light-Duty Diesel Engine |
| title_full_unstemmed | Asymmetric inlet valve opening to reduce NOx and soot from a High-Speed Light-Duty Diesel Engine |
| title_short | Asymmetric inlet valve opening to reduce NOx and soot from a High-Speed Light-Duty Diesel Engine |
| title_sort | asymmetric inlet valve opening to reduce nox and soot from a high speed light duty diesel engine |
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