In order to investigate the impacts of recirculated exhaust gas temperature on gasoline engine combustion and emissions, an experimental study has been conducted on a turbocharged PFI gasoline engine. The engine was equipped with a high pressure cooled EGR system, in which different EGR temperatures were realized by using different EGR coolants. The engine ran at 2000 r/min and 3000 r/min, and the BMEP varied from 0.2MPa to 1.0MPa with the step of 0.2MPa. At each case, there were three conditions: 0% EGR, 10% LT-EGR, 10% HT-EGR. The results indicated that LT-EGR had a longer combustion duration compared with HT-EGR. When BMEP was 1.0 MPa, CA50 of HT-EGR advanced about 5oCA. However, CA50 of LT-EGR could still keep steady and in appropriate range, which guaranteed good combustion efficiency. Besides, LT-EGR had lower exhaust gas temperature, which could help to suppress knock. And its lower exhaust gas temperature could reduce heat loss. These contributed to fuel consumption reduction. For HT-EGR and LT-EGR, IMEP was similar at every operating point, but LT-EGR had lower pumping loss than HT-EGR, which also helped to reduce fuel consumption. Based on the above-mentioned factors, it was found that LT-EGR could help to reduce fuel consumption by 1%~ 2%, and the fuel efficiency improvement was better at high loads. Engine emissions were also discussed.
Effect of EGR Temperature on PFI Gasoline Engine Combustion and Emissions
Sae Technical Papers
International Powertrains, Fuels & Lubricants Meeting ; 2017
2017-10-08
Conference paper
English
Effect of EGR Temperature on PFI Gasoline Engine Combustion and Emissions
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