This work attempts to analyse the ability of high free fatty acid (FFA) crude rice bran oil (CRBO) in replacing diesel partially in a compression ignition (CI) engine. It was observed that the delay period and the maximum rate of pressure rise for CRBO blends are lower than diesel and is almost inversely proportional to FFA content. Maximum heat release rate for CRBO blends are lower and occur earlier than that of diesel. CRBO blends require longer duration to release 90% of heat than diesel and it decreases with increase in FFA content of CRBO. When operating with CRBO blends, all emission parameters were decreased significantly with a marginal increase in CO emission than that of diesel without affecting the brake thermal efficiency of the engine. It is concluded that higher FFA of CRBO blends does not inhibit its ability to be utilised as a fuel in CI engines.
Keywords: crude rice bran oil, CRBO, free fatty acids, FFA, fuel blends, combustion, vegetable oil, diesel, compression ignition engines, brake thermal efficiency, alternative fuels, biodiesel