RESPONSE SURFACE METHOD TO OPTIMISE INJECTION TIMING, PERCENTAGE BLEND AND POWER OUTPUT OF A SEMI ADIABATIC ENGINE RUNNING ON BIODIESEL BLENDS

Experiments are conducted on Kirloskar Air cooled diesel engine using 10, 20 and 30% biodiesel blends of Simarouba and Rubber seed oils to study the performance of the engine. Conventional engine is convened into the semi adiabatic engine by coating piston crown with 300 microns of partially stabilized zirconia without altering compression ratio. Exhaustive experiments are conducted on the semi adiabatic diesel engine at rated and varying injection timings (20o - Retarded, 23o - Rated and 26o – Advanced timing, before top dead centre). Performance parameters such as Brake Thermal Efficiency (BTE), Brake Specific Fuel Consumption (BSFC) are computed, emissions like CO, NOx, un-burnt hydrocarbons etc., were recorded for both engines and are analysed. Response Surface Method is used to obtain models of the responses such as Brake Thermal Efficiency (BTE), Brake Specific Fuel Consumption (BSFC), CO and NOX. The results showed that BTE and BSFC of engine were improved for all blends tested at advanced injection timing. For all blends tested CO emission was decreasing and NOX emission was increasing at advanced timing. Optimisation of Injection Timing (IT), power output and percentage biodiesel blend was performed using desirability approach of Response Surface Method (RSM) for better performance and lower emissions. Amongst two biodiesels tested Simarouba biodiesel shown better performance. An injection timing of 25.5obtdc, power output of 3.608 kW and 19.5% of fuel blend could be considered as the optimum parameters for the test engine.