Effects of engine load and biodiesel content on performance and regulated and unregulated emissions of a diesel engine using contour-plot map.

This experimental study was conducted to explore the favorable and unfavorable conditions which promote or reduce the performance and emissions in a diesel engine, based on six engine loads (5% to 95% load) and five biodiesel contents including B0 (0% waste cooking oil biodiesel and 100% diesel, by volume %), B20, B50, B75 and B100 (pure biodiesel), at a constant engine speed of 1920 rpm. According to the results, the maximum brake specific fuel consumption was recorded at the lowest engine load (5% load) using B100; while the highest brake thermal efficiency was obtained at 80% load for B100. In regard to regulated emissions, the highest engine load (95% load) with diesel fuel was the condition for the formation of maximum CO, smoke opacity, PM mass, total particle number concentration and geometric mean diameter. The 95% load with B100 was the condition for maximum CO and NO. The 60% load with diesel fuel was the condition for maximum THC. For unregulated emissions, low engine load with B100 was the condition for maximum formaldehyde, acetaldehyde, ethene and propene. The maximum 1,3-butadiene was observed for B100 at 80% load. The highest benzene emission was recorded at 40% load for B100. The maximum toluene and xylene emissions were found at 5% load for diesel fuel. In addition, the conditions which lead to produce the minimum emissions are also extensively discussed in the present study.