Experimental study of the performance and emission characteristics of diesel engine using direct and indirect injection systems and different fuels

An experimental study of the performance and emission characteristics of diesel engine using direct and indirect injection combustion systems are carried out on a same model of two diesel engines fuelled with diesel and the blend of diesel and Chinese pistache biodiesel. The results show that the NOx emissions from the indirect injection combustion system (ICS) fuelled with diesel are reduced by around two thirds, compared to that from direct injection combustion system (DCS). Smoke emissions from the engine using ICS are all significantly lower than that of DCS, reduced by 70% for diesel; by 50–60% for the blend. The brake thermal efficiencies (BTEs) reduced by 8–10%, compared to that of DCS; the fuel consumptions increased by around 7–9%. It is also found that carbon monoxide (CO) emissions are reduced when the engine run at engine high power outputs, so are the hydrocarbon (HC) emissions from ICS at the peak power outputs. It is found that, when fuelled with the blend, the effects of ICS to the performance and emissions of diesel engine are very similar to that of running with diesel. For ICS engine fuelled with diesel and the blend fuel, the BSFCs for the blend are around 5% higher; the BTEs are around 2–4% lower; the reductions of NOx from the blend fuel are 5.1–8.4% on average for the ICS; the reductions of smoke from the blend fuel are 26.8–31.7% on average for the ICS. CO emissions are around a half lower; and HC emissions are around one fifth lower, compared to that of fuelling with diesel. Comparing to that of DCS fuelled with diesel, using ICS fuelled with the blended fuel has much lower emissions. NOx emissions decreased by 65.6% and 66.1%; smoke emissions decreased by 75.7% and 80.2%; CO emissions decreased by 55.8% and 46.0%; HC emissions decreased by 24.9% and 18.9%; with the BSFCs around 14.6–14.9% higher and the BTEs around 9.7–10.0% lower.