Combustion and Emission Characteristics of Jatropha and UCO Biodiesel Blends in Burner System

Abstract

This study investigates the combustion performance and emission characteristics of biodiesel blends derived from Jatropha Methyl Ester (JME) and Used Cooking Oil Methyl Ester (UCOME) in comparison to Conventional Diesel Fuel (CDF). Biodiesel was produced using a two-step transesterification process, producing high yields of 94.3% for JME and 92.0% for UCOME. Fuel blends were prepared at B5, B15, and B25 concentrations and tested in a lab-scale combustion chamber equipped with thermocouples and a gas analyzer. Key fuel properties such as specific gravity and calorific value were evaluated, showing that particular gravity increased with higher biodiesel content while calorific value decreased. For instance, CDF had the highest calorific value at 45.29 MJ/kg, whereas B100 biodiesels recorded lower values. Emissions analysis revealed that increasing biodiesel content significantly reduced NOx and CO emissions. At stoichiometric conditions (equivalence ratio 1.0), NOx emissions dropped from 61 ppm (CDF) to 51 ppm (B25 JME) and 52 ppm (B25 UCOME). CO emissions under the same conditions showed a reduction of up to 95.2% for B25 JME compared to CDF. The highest CO reduction occurred under stoichiometric combustion, while the most significant NOx reduction was observed at lean conditions, with B25 UCOME achieving a 40.5% decrease. These findings demonstrate the environmental advantage of biodiesel blends, particularly B25, which significantly reduces harmful emissions without compromising fuel performance.