Performance and emission analysis of CME-based mixed biodiesel blends in a compression-ignition engine

The global shift toward sustainable energy has heightened interest in biodiesel as an alternative to conventional diesel. In the Philippines, biodiesel production is primarily dependent on coconut methyl ester (CME), but concerns over copra supply have driven the need to explore alternative feedstocks. This study investigates the performance and emission characteristics of mixed biodiesel blends in a compression-ignition engine using locally available feedstocks, including Jatropha, Moringa, and waste cooking oil. Biodiesel blends were prepared by mixing CME with lower percentages of these alternative biodiesels and were tested alongside commercial diesel (B2) and the standard B5 blend. Engine performance was evaluated in a single-cylinder, four-stroke diesel engine using a hydraulic dynamometer, measuring key parameters such as torque, brake power, specific fuel consumption, and brake thermal efficiency. Emission analysis was conducted using an exhaust gas analyzer to assess carbon monoxide (CO), carbon dioxide (CO₂), hydrocarbons (HC), nitrogen oxides (NOₓ), and smoke density. Results indicate that biodiesel blends exhibited minor reductions in torque and power compared to conventional diesel, with MC5 (Moringa-CME blend) and WC5 (Waste Cooking Oil-CME blend) displaying the closest performance to commercial diesel. While biodiesel blends showed slightly higher fuel consumption, their emission characteristics demonstrated significant environmental benefits, particularly in CO and HC reduction. The study affirms the viability of mixed biodiesel blends as a sustainable alternative fuel in the Philippines, supporting the country’s biofuel initiatives while addressing challenges related to feedstock supply and energy security.