An Effect of Bio Diesel Fuel for Low Compression Ratio Diesel Engine

The purpose of this study is to explore an effect of the coconut oil methyl ester (CME) and vegetable oil methyl ester (VME) on a low compression ratio diesel engine performance. CME and VME were produced from coconut oil and vegetable oil with methanol, respectively. Vegetable oil was assumed to contain 60 wt.% of soybean oil and 40 wt.% rapeseed oil. The engine performance was measured in the steady operating condition at 3600 rpm of engine speed. The ignition timings of CME and VME were advanced and the maximum cylinder pressures of CME and VME were higher as compared with the diesel fuel at low compression ratio, because CME and VME consisted of medium chain fatty acid methyl esters. The ignitability of CME was superior to VME, because CME consisted of saturated fatty acid. The brake thermal efficiency of diesel fuel was slightly higher than CME and VME at any compression ratios. THC and CO concentrations of CME and VME were lower than diesel fuel at low compression ratio, because CME and VME were oxygenate fuel. THC and CO concentrations of CME were lower than VME, because CME had more oxygen than VME. NOx concentration of CME was lower than diesel fuel and VME for any compression ratios in the high load operation, because the maximum rate of heat release of CME was lower than diesel fuel and VME. Therefore, CME and VME could be adaptable as alternative fuel for a low compression ratio diesel engine.