Investigation of DI-CI four-stroke VCR engine at different static injection timings using biofuel derived from non-edible oil source as a fuel

This paper presents the effect of static fuel injection timings and blends of biodiesel with conventional diesel on the performance and emission characteristics of a DI-CI VCR engine. Blends of Honne oil methyl ester (HnOME) and diesel was used as fuel. The default value of static injection timing of the engine was 23 degrees bTDC (before top dead centre). Injection timing was retarded and advanced from default value by 4 degrees bTDC. Experiments were conducted at three levels of timings using the blends B20, B40, B60, B80 and B100 (pure HnOME). Conventional diesel was used as a reference fuel. The decrease in brake thermal efficiency for B20, B40, B60, B80 and HnOME compared to diesel at 19 degrees bTDC were 5.4, 15.7, 13, 10 and 2.9% respectively. Brake thermal efficiency decreased by 4.2, 15.7, 13.5, 10.15 and 2.96% for B20, B40, B60, B80 and HnOME respectively compared to diesel at 27 degrees bTDC. Nitric oxide emissions reduced for both advanced and retarded timings, but the reduction was more for retarded timing. Smoke intensity increased for retarded timing. Blend B60 to B80 can be successfully used by retarded timing combined with higher compression ratio and fuel injection pressure.