Effects of Waste Cooking Oil Biodiesel on Performance, Combustion and Emission Characteristics of a Compression Ignition Engine

Abstract

With their higher sustainability index, biofuels, environmentally-friendly and renewable nature is a viable alternative energy source in the transportation sector. This study presents the effect of waste cooking oil (WCO) biodiesel on performance, combustion, and emission from a compression ignition engine. The biodiesel was blended with diesel in varying proportions of 5% biodiesel and 95% diesel (designated as B5), 10% biodiesel in diesel (B10), 15% biodiesel in diesel (B15), 20% biodiesel in diesel (B20), 50% biodiesel in diesel (B50), and 85% biodiesel in diesel (B85). Simulation of a 2-cylinder diesel engine fueled with diesel, biodiesel blends and pure biodiesel was carried out using Ricardo Wave software and the results obtained were validated. The engine speed was varied from 1200 rpm to 3200 rpm at full load condition using a positive valve overlap of 32°. Performance results showed that WCO biodiesel blends at 1200 rpm produce brake-specific fuel consumption of, 0.240109 kg/kWhr, 0.241996 kg/kWhr, 0.244331 kg/kWhr, 0.24661 kg/kWhr, 0.26089 kg/kWhr, 0.27947 kg/kWhr and 0.28798 kg/kWhr for B5, B10, B15, B20, B50, B85 and B100 respectively, as compared to 0.239383 kg/kWhr of diesel fuel while the brake power and torque reduced at full load with varying speed. Combustion analysis showed similar trends between diesel and biodiesel blends whereas biodiesel blends produced shorter ignition delay, shorter combustion duration, and lower heat release rate. Emission levels of CO, reduced by 1%, 10%, 15%, 22%, 48%, 68% and 74% with B5, B10, B15, B20, B50, B85 and B100 respectively at 1600 rpm when compared to diesel fuel. HC emission was reduced by 9% with B100. NO<sub>x</sub> levels slightly increased when B5, B10, B15, and B20 at 1200 rpm and B10 and B15 at 1600 rpm were fueled in the engine. The exhaust gas temperature (EGT) of B5, B10 at 1600 rpm was higher than diesel fuel and B5, B10 at 2400 rpm to 3200 rpm EGT was higher than diesel fuel. Generally, biodiesel blends showed better emission levels and other combustion and performance levels are within acceptable limits.