Prediction of Cetane Number for Biodiesel Fuels: Karanja, Jatropha, Sunflower, Palm and Waste Cooking Oil Methyl Esters

Cetane number of diesel fuels is an important parameter because of its direct impact on the performance, emission and combustion-generated noise in diesel engines. Conventional method of determining the cetane number requires CFR engine with primary reference fuels. This process is well established for diesel fuel even though it is a costlier and time-consuming process. In this work, an attempt was made to develop correlations to predict cetane number for selected bio fuels. The biofuels considered were Karanja methyl esters (KME), Jatropha oil methyl esters (JTME),Sunflower methyl esters (SFOME), Palm oil methyl esters (POME) and Waste cooking oil methyl esters (WCOME). Chennai Petroleum Corporation Limited, Chennai, India supplied fuels with known cetane numbers of 25, 51 and 63. These reference fuels were tested in a 4.4 kW naturally aspirated stationary, air-cooled, four-stroke, direct injection engine coupled with an electrical dynamometer. This engine was instrumented with AVL piezo-electric pressure transducer and angle encoder. The transducer and the angle encoder were interfaced with personal computer to store the pressure versus crank angle data. The AVL Indimeter software was used to analyze the collected data. Initially, experiments were conducted with fuels of known cetane number at various loads. From these results ignition delay was determined and tabulated for the above conditions. The correlations were developed based on ignition delay for the known cetane number of fuels at all loads. The same experimental procedure was followed for all the bio-fuels. The correlations were used to find the cetane number of bio-fuels. It was found that cetane number predicted by the correlations matched with available data for the bio-fuels.