A study of a GCI engine fueled with gasoline-biodiesel blends under pilot and main injection strategies

A study was conducted to compare gasoline with the addition of 5% by volume of biodiesel (GB05) to 100% neat diesel using the multiple injection strategies in a gasoline compression ignition (GCI) engine. The engine was tested at 1200 rpm using 70 MPa of injection pressure and multiple injections, which consisted of a pilot injection at the 350-degree crank angle before top dead center (°C A BTDC) for approximately 1140 μs, followed by the main injection at 40 °C A BTDC for around 350 μs. The results show that low-temperature combustion can be achieved for GB05 with multiple injections at an in-cylinder temperature of approximately 1800 K. The heat release rates (HRR) for multiple injections of GB05 were lower than that for a single injection of 100% diesel. However, it is higher than those of multiple injections of 100% diesel and a single injection of GB05. Using multiple injections and increasing the temperatures of the intake, oil and engine coolant could result in improved combustion and engine efficiency. Multiple injections of GB05 showed decreased carbon monoxide (CO) emissions, which could be due to the pilot injection of GB05. The biodiesel content and using gasoline as a highly volatile fuel in GB05 showed the significant effect of lowering total hydrocarbon (THC) and CO emissions. However, nitrogen oxide (NOx) emissions from GB05 for both the multiple and single-injection modes seem to be higher than those of multiple injections of 100% diesel and even higher than those of a single injection of 100% diesel, which is due to the oxygen content in the GB05 fuel.