Experimental investigation and optimization study of combustion chamber geometry on performance and emission parameters using Rice bran biodiesel

An experimental investigation and optimization study of various piston geometries was conducted on Greaves single cylinder direct injection compression ignition engine using straight diesel and blends of rice bran biodiesel. The three combustion chamber geometries used in this study were Standard toroidal piston (STP), hemispherical bowl piston (HBP) and Shallow toroidal re-entrant piston (STRP) at compression ratios of 18:1, 19.04:1 and 16.4:1 respectively. Rice bran biodiesel was derived by two step trans-esterification process with an optimum yield of 86% with molar ratio 1:6, 06% of catalyst (KOH), 90 min reaction time and 65 o C reaction temperature. The performance parameters like brake specific energy consumption, brake thermal efficiency and the emission parameters like carbon monoxide, unburned hydrocarbons and oxides of nitrogen were analysed in detail. It was noticed that the BSEC of STRP was 12.1% with diesel and 14.02% with B100 biodiesel blend. The brake thermal efficiency was also found to be improved with biodiesel blend with STRP on comparison with STP and HBP. The carbon monoxide and hydrocarbon emission was found to decrease with STRP geometry were as HBP exhibited negative improvement. NOx emission was also found to increase with STRP.