Effect of Compression Ratio on the Performance and Emission Characteristics of CI Engine for a Blend of Soapnut Oil, Cottonseed Oil Methyl Ester and Diesel

In the present work, soap nut oil, cotton seed oil methyl ester and diesel were blended in the proportion of 10:15:75 by volume to form a bio diesel blend of B25. It has been observed that the calorific value is lower and viscosity is higher for B25 as compared to diesel. The performance and emission characteristics were studied using a variable compression ratio diesel engine test rig for three different compression ratios of 17, 17.5 and 18. The results showed that the brake thermal efficiency has increased by 5.2% at a compression ratio of 18 compared to the brake thermal efficiency at a compression ratio of 17. Brake specific fuel consumption has decreased by 4.7% with the increase in compression ratio. However the brake thermal efficiency for B25 is lower than that of diesel. It has been observed that the NO x emissions are higher by 2% and hydrocarbon emissions and smoke opacity are lower by 55.5% and 12.4% respectively for B25 as compared to diesel at full load.