Experimental probe into an automative engine run on waste cooking oil biodiesel blend at varying engine speeds

Abstract

The present work attempts to evaluate the performance of an automotive diesel engine run on waste cooking oil biodiesel (WCO) blend at variable engine speeds. The composition of the blend (B40) used in the study is 40% WCO and 60% diesel by volume and the engine used for the experimentation is a naturally aspirated, watercooled and direct injection type having a compression ratio of 18:1. The engine settings used in the study are an injection timing (IT) of 150 bTDC and a fuel injection pressure (IP) of 500 bar. The performance and emissions characteristics of the automotive engine are studied at various loads of 20%, 40%, 60%, 80% and 100% and at different engine speeds of 1500, 1800 and 2400 rpm. The first two rotational speeds are chosen to study the stationary power generation capabilities of the blend, while the feasibility of blend for automotive applications has been evaluated at 2400 rpm. Experiments have also been conducted on the engine run on mineral diesel fuel in order to make a comparative analysis. At full load, the maximum brake thermal efficiency (BTE) is found to be 21.51%, 25.48% and 23.56% for the blend at 1500, 1800 and 2400 rpm, respectively. At 2400 rpm and at 20% and 40% loads, the blend shows an absolute improvement in BTE of 0.17% and 0.03%, respectively over diesel fuel. On an average, there is a decrease of carbon monoxide (CO) emissions by 87.5%, 22.22% and 14.28% at 1500, 1800 and 2400 rpm as compared to diesel fuel. At 1500 and 2400 rpm, there is an average absolute increase in hydrocarbon (HC) emissions by 1.6 ppm and 9.6 ppm, respectively; while at 1800 rpm, an average decrease in HC emissions by 4 ppm is observed vis-a-vis diesel fuel. While emissions of oxides of nitrogen (NOx) as compared to diesel fuel increased on an average by 19.43%, 26.09% and 1.01% at 1500, 1800 and 2400 rpm, respectively.