Performance, combustion and emission tests of a metro-bus running on biodiesel-ULSD blended (B20) fuel

摘要

A diesel engine driven metro bus was tested in a chassis dynamometer with 20% biodiesel mixed with 80% ultra-low sulfur diesel (ULSD), termed B20, to find out its performance, combustion characteristics and emissions. In this study, B20 was chosen instead of 100% biodiesel (B100) due to the fact that, with lower calorific value of B100, the engine could potentially lose power and torque which would make the bus unsuitable to climb hills with full load during peak hours. The performance of the bus such as torque and power with B20 were found to be very similar to ULSD. Therefore, there was no drivability issue with B20. The combustion characteristics of B20 and ULSD were also found to be very similar with B20 having 4.8° more combustion duration than ULSD due to low volatility and presence of heavier molecules in biodiesel. In terms of emissions, CO and HC were reduced but NO_x was increased by an average of 4.4% mainly due to inherent presence of oxygen in biodiesel. It was also found that with B20 the emission of PM_(10) particulates were 19% and 47% lower at lower and higher speeds, respectively. Based on the findings, it can be concluded that B20 is a suitable choice of alternative renewable fuel for existing diesel engine that needs little or no modifications to improve the sustainability of fuel and reduce environmental emissions.