An investigation of the engine performance, emissions and combustion characteristics of coconut biodiesel in a high-pressure common-rail diesel engine

An experimental investigation on engine performance, emissions, combustion and vibration characteristics with coconut biodiesel fuels was conducted in a high-pressure common-rail diesel engine under five different load operations (0.17, 0.34, 0.52, 0.69 and 0.86 MPa). The test fuels included a conventional diesel fuel and four different fuel blends of coconut biodiesel (B10, B20, B30 and B50). The results showed that biodiesel blended fuels have significant influences on the BSFC (brake specific fuel consumption) and BSEC (brake specific energy consumption) at all engine loads. In general, the use of coconut biodiesel blends resulted in a reduction of BSCO (brake specific carbon monoxide) and smoke emissions regardless of the load conditions. A large reduction of 52.4% in smoke opacity was found at engine load of 0.86 MPa engine load with B50. For combustion characteristics, a slightly shorter ignition delay and longer combustion duration were found with the use of biodiesel blends under all loading operations. It was found that generally the biodiesel blends produced lower peak heat release rate than baseline diesel. The vibration results showed that the largest reduction of 13.7% in RMS (root mean square) of acceleration was obtained with B50 at engine load of 0.86 MPa with respect to the baseline diesel.