Experimental investigation on the behavior of a DI diesel engine fueled with raw biogas-diesel dual fuel at different injection timing

This study is aimed to investigate the combustion, performance and emission characteristics of a direct injection (DI) diesel engine, modified to operate with raw biogas-diesel dual fuel. The injection timing of diesel was varied from 23 °CA bTDC to 27.5 °CA bTDC in steps of 1.5 °CA, in the dual fuel operation. The results indicated that, dual fuel operation with the injection timing of 26 °CA bTDC gave an overall better result, than other injection timings. The brake specific carbon monoxide (BSCO) and brake specific hydrocarbon (BSHC) emissions were higher by about 2% and 10% respectively, than diesel operation, at full load. At full load, the smoke emission was lower by about 39% than that of diesel. The cylinder peak pressure was higher by about 14 bar and the brake specific fuel consumption (BSFC) was higher by about 25%, than those of diesel operation, at full load. At part load, the engine performance in the dual fuel operation was improved with advanced injection timing, with significant reduction in the exhaust emissions. The brake specific nitric oxide (BSNO) emission was higher with advanced pilot injections, than that of original injection timing but, it was about 16% lower than diesel, at full load.