기계식 디젤엔진의 디젤-천연가스 혼소화를 통한 디젤 대체율 향상 연구

An experimental study was performed to provide the effect of PM reduction and the improvement of diesel alternative ratio utilizing diesel-natural gas dual-fuel combustion mode in a retrofit 3.4-liter diesel engine. In order to achieve the same power as the original diesel engine, engine control unit (ECU) of the dual-fuel engine was calibrated. During this calibration, the amount of diesel fuel injection was fixed same as the amount in the idle state for all engine load conditions and liquefied natural gas (LNG) fuel injection was adjusted to increase power based on the power in idling state. LNG fuel was injected by a single point injection at the inlet of intake air manifold. As a result, diesel alternative ratio was improved in overall through making up the characteristic of lower diesel fuel consumption in comparison with mechanical diesel engine. Diesel alternative ratio was calculated from the experimental data acquired from full load test. It was found that the maximum value of diesel alternative ratio was about 96%. Finally PM emission experiment was performed in C1-8 mode cycle and it was shown PM emission was extremely reduced down to 7.42*10 -7 g/kWh comparing with mechanical diesel engine. From these results we believe our dual-fuel engine could meet Tier-4 regulations.