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Effect of Reduced Valve Overlap on Emission Characteristics of Hydrogen-Compressed Natural Gas Engine

수소-천연가스엔진에서 밸브오버랩 감소가 배기특성에 미치는 영향

  • Received : 2014.04.28
  • Accepted : 2014.09.22
  • Published : 2015.01.01

Abstract

In order to meet the current emission regulations (EURO-6), it is necessary to significantly reduce $CH_4$ and $NO_X$ emissions. This study investigated the effect of a reduction in the valve overlap on the combustion and emission characteristics of a hydrogen-compressed natural gas engine under a part-load operating condition. The combustion and emission characteristics were analyzed for each fuel using the original camshaft and an altered camshaft with reduced valve overlap. The results showed that the thermal efficiency was decreased and the fuel flow was increased when using the altered camshaft. The $CO_2$ and $CH_4$ emissions were increased as a result of the reduced thermal efficiency. Under lean operating conditions, the $NO_X$ emission was decreased compared with one of the conventional camshaft. Thus, under the same fuels and operating conditions, it had a harmful influence on the emission characteristics and thermal efficiency.

현행 배기가스규제인 유로6을 대응하기 위해선 질소산화물과 메탄의 배출량을 크게 저감시켜야 하는 실정이다. 본 연구에서는 부분부하운전조건에서 밸브오버랩 감소가 수소-천연가스엔진의 연소 및 배기특성에 미치는 영향을 살펴보았다. 각 연료와 기존캠 및 밸브오버랩이 감소된 변경캠에 대하여 연소 및 배기특성을 분석하였다. 실험결과 변경캠을 사용하였을 때 열효율이 감소하고 연료유량이 증가하였다. 열효율 감소로 인하여 메탄과 이산화탄소의 배출량은 증가하였다. 희박한 운전조건에서 질소산화물 배출량은 기존캠 대비 감소하였다. 동일한 연료 및 운전조건에서는 효율과 배기특성에 악영향을 미치는 것을 알 수 있었다.

Keywords

References

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