Abstract:
Experimental studies have been carried out to investigate effects of biodiesel fuels on diesel engine performance and emissions characteristics. Biodiesel fuels are prepared from cotton seed oil, palm oil and flax oil to use as an alternative fuel for diesel engine. Biodiesel emissions and performance parameters are compared with the base diesel fuel using single cylinder air cooled direct injection diesel engine with and without exhaust gas recirculation (EGR) for different engine speeds. Viscosity and density of different fuels are measured at different temperatures to determine the temperature at which the viscosity has minimum difference between biodiesel and diesel fuels to decrease viscosity effects on the results. The results indicate that biodiesel fuels give slightly less brake power, brake thermal efficiency and slightly higher brake specific fuel consumption and higher fuel mass flow rate per cycle. Diesel fuel gives lower CO and CO2 concentrations than biodiesel fuels due to lower carbon/hydrogen ratio and higher heating value. Biodiesel fuels give higher NOX concentrations than diesel fuels due to higher oxygen concentrations in biodiesel molecules and higher cetane number. The main parameters affecting biodiesel fuels combustion are viscosity, density, oxygen content, centane number, heating value and fuel compositions which are the basic parameters for analysis the results. Using EGR increases CO concentrations and decreases NOX concentrations due to decrease flame temperature. Also, exhaust gas temperature (TExhaust), oil temperature (TOil), wall temperature (TWall), cylinder pressure are measured with/without EGR. TExhaust and TOil for biodiesel fuels are higher than that for diesel fuel. TWall for diesel fuel is higher than all biodiesel fuels. Fluctuation in TExhaust is higher than fluctuation in TOil and TWall respectively. Biodiesel fuels give maximum cylinder pressure higher than diesel fuel. The present work contributes in using biodiesel fuels as alternative fuel for diesel engine and decreasing diesel engine emissions. The position of maximum cylinder pressure are arrangement as 11 crank angle (CA) degree after top dead center (ATDC) for flax, 12 CA degree ATDC for cotton, 14 CA degree ATDC for palm and 20 CA degree ATDC for diesel fuel respectively