An experimental study on low temperature combustion in a light duty engine fueled with diesel/CNG and biodiesel/CNG

摘要

Low temperature combustion potentially can improve engine efficiency coupled with the benefits of low nitrogen oxides, and particulate matter emissions, and vice versa high unburned hydrocarbon and carbon oxide emissions through in-cylinder fuel reactions. In this survey, the experiments were carried out using a modified one-cylinder reactivity controlled compression ignition engine, dual-fueled diesel/compressed natural gas and biodiesel/CNG, to investigate the effects of direct injection strategies on the engine combustion efficiency and emission characteristics. Different ratios of biodiesel blends at different premixed ratios were applied to the dual-fuel engine. The results showed that the start of liquid fuel direct injection timing has a crucial role in the performance and emission characteristic of dual-fuel RCCI combustion. Advancing liquid fuel direct injection timing increased thermal efficiency and NOx emission while UHC and CO emission decreased due to stratification of premixed fuel and increasing temperature and in-cylinder pressure rise rate. Using biodiesel with low lower heating value indirect injection of liquid fuel reduced the maximum pressure rise rate resulting in reduction of NOx emission while increasing UHC and CO. Besides, increasing premixed ratio decreased thermal efficiency but increased UHC emission due to over premixed rich charge.