Effects of animal fat based biodiesel on a TDI diesel engine performance, combustion characteristics and particle number and size distribution emissions

The aim of the study is to evaluate the influence of the animal fat based biodiesel/diesel fuel blends in comparison with pure diesel and soybean biodiesel blends over the engine performance, the specific fuel consumption and emissions, especially on particle emissions in size (5.6–560 nm) and number distribution of a diesel engine. Tests were conducted in engine test bench with 6 animals fat based blends of animal fat based biodiesel/diesel and soybean biodiesel/diesel in different proportions B10 (10% biodiesel and 90% pure diesel fuel), B20, B25, B30, B40, B50 and D100 (pure diesel). Tests were performed on a Euro 4 diesel engine, following an Urban Driving Cycle and 5 stationary operating conditions (15, 30, 50, 70 and 100 km/h). Experimental results show that the ratio of the blend biodiesel/diesel, followed by the saturation level of biodiesel, is the parameter that most influence has on the emission of pollutants. The nitrogen oxides emission increases compared to pure diesel and particle number emission decreases significantly, especially when the concentration of biodiesel is greater than 25%. The geometric mean diameter of the particles from biodiesel presents trends consistent with the load and speed variation and has no dependence on the type of biofuel used and is always less than those measured for mineral diesels. In all engine operating conditions, it was observed that particle emissions from the combustion of animal fat based biodiesel with a percentage higher than 40%, are emitted in smaller quantities than with the same proportions of soybeans.