Effect of injection pressure, exhaust gas recirculation and Swirl Ratio on autoignition, combustion and engine out emissions in a HSDI engine fueled by soybean biodiesel blend (B-20)

To reduce the dependency on fossil fuels, various alternate energy sources have been considered in order to meet our daily energy requirements. Such renewable energy sources that have been the center of attention in the automotive community include Bio-fuels such as Ethanol and Biodiesel.;In the recent past, researchers have reported different emission levels of Oxides of Nitrogen (NOx) from engines fueled with biodiesel blends with diesel fuel, particularly B-20. Some researchers reported that Biodiesel increased NOx emissions when compared with regular diesel fuel. This increase in NOx has been attributed to physical properties such as the higher bulk modules of biodiesel, which would promote an advance in fuel injection timing and produce higher cycle temperatures. The increase in NOx was reported to be more prominent in the pump-line-nozzle and unit injection systems, but would not appear to be relevant in high-pressure common rail injection systems. However, other researchers reported that NOx emissions from biodiesel B-20 are comparable if not lower than engine out emissions from an engine fueled with regular diesel fuel. This has been attributed to the lower volatility of B-20 compared to regular diesel.;The focus of this study is to determine the effect of using B-20 (a blend of 20% soybean methyl ester biodiesel and 80% ultra low sulfur diesel fuel) on the combustion process, performance and exhaust emissions in a High Speed Direct Injection (HSDI) diesel engine equipped with a common rail injection system. The engine was operated under simulated turbocharged conditions with 3-bar indicated mean effective pressure and 1500 rpm engine speed. The experiments covered a wide range of injection pressures, EGR rates and Swirl Ratios. The rate of heat release trace has been analyzed in details to determine the effect of the properties of biodiesel on auto ignition and combustion processes and their impact on engine out emissions. An analyze was made to correlate the ARHR during fuel evaporation and endothermic reactions, premixed and mixing controlled combustion fractions with the properties of the fuel and different operating conditions. The operating conditions that result in an increase or a decrease in NOx emissions have been identified.