Combustion and Emission Characteristics of Straight Vegetable Oils and Diesel Fuel Blends

An experimental investigation was carried out to evaluate the performance and emission characteristics of vegetable oils blends with diesel oil as an alternative fuel. Virgin and waste frying vegetable oils of sunflower, corn, soybean and palm oils were collected and characterized with GC-FID. Nine blends of various vegetable oils and diesel were prepared. The important chemical and physical properties of the blends (including kinematic viscosity, heat of combustion, exhaust emissions (SOx and NOx), flash point, pour point, cloud point, sulfur content, density and specific gravity) were compared to those of diesel oil. Generally, there is no significant difference between the use of waste or virgin vegetable oils blends with diesel oil. Among the various blends, those containing up to 30% vegetable oils have viscosity, pour point, cloud point and density values close to those of diesel oil. These blends have approximately 95% of the heat of combustion, but have the advantages of higher flash point and lower emissions compared to those of diesel oil. Blends of 30% vegetable oils have comparable performance and emissions characteristics to those of diesel oil fuel and found to be good substitute for diesel.