Combustion Performance of Jatropha and UCO Biodiesel Blends Under Varying Equivalence Ratios

Abstract

This study investigates the combustion characteristics of biodiesel blends derived from Jatropha Methyl Ester (JME) and Used Cooking Oil Methyl Ester (UCOME) under various equivalence ratios (Φ = 0.8, 1.0, 1.1, and 1.2). The biodiesels were produced through a two-step transesterification process, yielding 94.3% for JME and 92.0% for UCOME. Combustion experiments were conducted in a horizontal combustion chamber using a data logger and K-type thermocouples to record wall temperatures. Blends with conventional diesel fuel (CDF) were prepared at 5%, 15%, and 25% biodiesel concentrations. Results showed that wall temperature decreases as the percentage of biodiesel in the blend increases. At stoichiometric conditions (Φ = 1.0), the highest wall temperature was recorded for CDF at 847.03°C, while B25 JME and B25 UCOME recorded the lowest at 782.43°C and 791.09°C, respectively. The percentage reduction in maximum temperature relative to diesel was 7.6% for B25 JME and 6.5% for B25 UCOME. Increasing equivalence ratios led to a rise in wall temperatures across all blends. From Φ = 0.8 to 1.0, temperature increased by up to 10.6% for B15 JME, while from Φ = 1.0 to 1.2, B25 JME saw an increase of 6.6%. The findings confirm that biodiesel blends produce lower combustion temperatures due to reduced energy content and heating values. Nonetheless, all tested biodiesel blends successfully sustained combustion under varying air-fuel ratios, indicating their potential as alternative fuels for low-emission combustion systems.