Experimental Emissions and Fuel Economy Analysis of a Diesel Engine Operating on Vegetable Oil

Plant based oils or vegetable oils (VO) may be an alternate fuel to diesel for heavy duty diesel applications. The object of this study was to compare the emissions and fuel economy of a diesel engine operated on both diesel fuel and VO. This was achieved by experimentally comparing the soot and gaseous exhaust emissions from a diesel engine that was operated on both VO and diesel fuel. A 1.9L GM/Vauxhall diesel engine was mounted on an Eaton 225 HP AC Engine Dynamometer. The engine's soot production output was measured using an AVL 483 Micro Soot Sensor and the gaseous exhaust emissions were analyzed using a HORIBA Mexa 7200-D. Tests were conducted at six steady state test modes of different engine speeds and loads. It was determined that the engine exhaust emissions was similar for both VO and diesel fuel. However, the soot production for VO was higher under maximum load and high speed testing conditions. This study suggests that VO is an effective substitute for diesel fuel. However, it must be noted that these tests were conducted using a warm engine. The high viscosity of VO at low temperatures offers engine design challenges. These challenges may be overcome by using aftermarket conversion kits.