Combustion and emission characteristics investigation of diesel-ethanol-biodiesel blended fuels in a compression-ignition engine and benefit analysis

This study has investigated feasibility to use ethanol in a compression ignition engine by blending it with diesel fuel, called diesohol. Additionally, biodiesel, acting as a co-solvent, is mixed into diesohol to prevent phase separation. Three blended ratios including B3E5, B7E5 and B10E10 were selected to conduct fuel property analysis and the engine test. In addition, commercial diesel in Thailand (B7) was used as a referent fuel. A commercial diesel engine with common rail fuel system was used to measure engine performance, fuel consumption, exhaust gas emissions including aldehydes as well as combustion characteristics. Benefits of using the diesohol fuel in pickup truck were also investigated. The results showed that with increasing ethanol fraction, the biodiesel fraction needed to be increased to prevent phase separation. When ambient temperature was decreased the phase separation could easily occur. Engine torque and power decreased when percentage of ethanol increased. In-cylinder pressure analysis showed that pilot combustion was moderated and retarded due to higher heat of vaporization of ethanol. With ethanol fraction increasing, the blended fuels required more time to evaporate, induced to higher heat release rate due to long ignition delay. Hydrocarbon emission was increased with longer period of fuel vaporization and mixing processes while the nitrogen oxide increased with increasing of maximum heat release rate. However, the diesohol can help facilitate biofuel market management by increasing biofuel (both ethanol and biodiesel) from diesel sector. In addition, fossil fuel will be suppressed and global warming impacts will be mitigated with diesohol supported measures.