| OPTIMIZE COMBUSTION OF COMPRESSED NATURAL GAS ENGINE BY IMPROVING IN-CYLINDER FLOWS |
| X. YU |
| Jilin University |
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| ABSTRACT |
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In order to solve the problem of slow flame propagation in a spark-ignition engine fueled with compressed natural gas (CNG), the influence of in-cylinder flows on combustion process was investigated in CA6SE3-21E4N CNGengine by means of numerical simulation and experiment. The status of in-cylinder flows from intake to expansion stroke was described by computational fluid dynamic tool, which revealed that the in-cylinder flows were one of the main reasons of slow burning rate. Therefore, a special-shaped combustion chamber called Cross was used to improve the in-cylinder flows. The results showed that peak turbulent kinetic energy of Cross was 43.9% higher than that of original combustion chamber called Cylinder during the late compression period at 1450 rpm 100% load. The combustion parameters, brake specific fuel consumption (BSFC) and regulated emissions were obtained by means of experiment. At 1450rpm 25%, 50%, 75% and 100% load conditions, the ignition delay of Cross was longer than that of Cylinder, moreover, the Cross produced averagely 5.75oCA shorter combustion duration. The BSFC of Cross was on an average of 4.3% reduction at 1450 rpm as well as the HC and CO emissions were reduced whereas the NOx emissions were significantly increased. |
| Key Words:
CNG engine, In-cylinder flows, Combustion chamber, Combustion, Emissions |
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