Performance Optimization of Partial Load of Gasoline Engine at Critical Knock Status Using Hot Exhaust Gas Recirculation[J]. 2015, 49(10): 116-122.
DOI:
Performance Optimization of Partial Load of Gasoline Engine at Critical Knock Status Using Hot Exhaust Gas Recirculation[J]. 2015, 49(10): 116-122.DOI: 10.7652/xjtuxb201510019.
Performance Optimization of Partial Load of Gasoline Engine at Critical Knock Status Using Hot Exhaust Gas Recirculation
Effects of hot exhaust gas recirculation(EGR)on partial load performance of a gasoline engine are studied using the software CFD Fire based on a 1.4 L gasoline direct injection(GDI)engine and its calibrated and experimental data. Results show that increasing hot EGR rate increases the knock index when the intake pressure are 68 kPa and 24 kPa within knock limit
but the knock index is significantly below that in same intake temperature conditions without EGR. Both enhancement of combustion and reduction of pumping loss can be acquired by introducing hot EGR. The indicated work increases by
4.6% when the intake pressure is 68 kPa and η
hot
=10%
and it increases by 65.8% when the intake pressure is 24 kPa and η
hot
=17.5%
compared with that in normal intake temperature condition. The flame propagation velocity is almost the same as the one under the normal intake condition when η
hot
is 12.5% and the intake pressure is 24 kPa
and the peak cylinder pressure increases by about 1/4. Moreover
emissions of CO and NO are reduced by 52% and 78.3%
respectively. Great potential for further application of hot EGR exists by coupling heating intake air or cooling EGR
and more significant improvements can be obtained by coupling heating intake air with lower loads.
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references
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