Biodiesel is a viable alternative fuel used in compression ignition (CI) engines because of its non-toxicity, biodegradability and renewability. Raw material and production process are factors that affect the cost of biodiesel. The use of waste cooking oil (WCO) as the fuel feedstock and microwave heating technology is able to reduce the cost of biodiesel. In this study a continuous flow transesterification of WCO by microwave irradiation for biodiesel production using calcium oxide (CaO) from cockle shell as the catalyst has been investigated. The catalyst was packed inside a plastic container that is mounted on a stirrer shaft and inserted inside the reactor.
Response surface methodology (RSM) and Box–Behnken design were employed to study the relationships of power input, stirrer speed and liquid hourly space velocity (LHSV) on waste cooking oil methyl ester (WCOME) conversion. The WCOME produced was tested on a small-unmodified direct injection diesel engine to investigate the performance and exhaust emissions and then compared with the commercial diesel fuel (Petron diesel max, PDM) and commercial biodiesel (palm oil methyl ester, POME). Experimental measurements of engine performances, exhaust emissions, cylinder pressure and heat rate release were performed as a function of engine load at a constant engine speed. The optimum conditions of the transesterification of WCO
have been found to be power input 445 W, stirrer speed 380 rpm and LHSV 71.5 h-1 hand yielded a maximum WCOME conversion of 72.5%. The performance, emission and combustion of a one-cylinder Yanmar Diesel engine L70 using PDM containing 7% methyl ester, two blends of PDM with POME and two blends of PDM with WCOME equivalent to B10 and B20, respectively, were investigated. The performance, emission and combustion test results of five test fuel PDM, BP10, BP20, BW10 and BW20 were then compared with the simulation results by using GT-SUITE V6.0 software. The experimental results indicated that using POME and WCOME blends resulted in increment in break specific fuel consumption (BSFC) up to 5.9% and reduction in brake thermal efficiency (BTE) up to 29.3% compared to PDM. These biodiesel blends also increased NOx emissions and decreased CO2, CO and Uhc emissions for all engine loads at constant speed of 2500 rpm. Both experiment and simulation of the maximum cylinder pressure increase significantly with the increase of engine load for each test fuel. All the simulation graphs show the similar trend compared to experiment.