Experimental investigations on the performance and emissions characteristics of dual biodiesel blends on a varying compression ratio diesel engine

The present work discusses the performance and emissions characterization of dual biodiesel sample blends on a varying compression ratio diesel engine. The dual biodiesel blends were obtained by blending two biodiesels (Mahua and Jatropha) in equal proportions volume (1:1, v/v) with mineral diesel. The sample blends were obtained on a ‘percentage by volume’ basis and named B10, B20, B30, and B40 (B10 was a blend of 5% each biodiesel with 90% mineral diesel and similarly for all other sample blends). All the experiments were performed at a constant engine speed of 1500 rpm, 50% loading conditions (2.6 kW), and varying compression ratios of 13.5:1, 14.5:1, 15.5:1, and 16.5:1. The results revealed that the sample blends had slightly higher brake power and mechanical efficiency with sample blends B10 to B40 had (0.15–1.58%) higher brake power and (1.07–12.42%) higher mechanical efficiency as compared to mineral diesel at a compression ratio of 16.5:1. The In-cylinder peak pressure and exhaust gas temperature were observed to be lower than mineral diesel for the sample blends B10 to B40 by 0.15–0.36 bar and 11.1–69.8 ℃, respectively. Also, the emissions of carbon monoxide and hydrocarbons were lower by 33–62%, respectively, for the sample with the highest blend percentage. However, the carbon dioxide emissions were found to be higher by 42.85% than mineral diesel. From the overall performance and characterization, it is concluded that B20 had optimum properties and blend percentage to be a better substitute fuel for mineral diesel among all the tested samples.