The Development of Engine Prototype Powered by Diesel and LPG as Fuel for Agriculture

Abstract

According to the research entitled “the innovative engine prototype powered by diesel and LPG as fuel for agricultural” in 2019, the problems found while using the engine were as follows: the accumulated heat in the auxiliary combustion chamber reached 300 °C in case of gasoline engine use and a lot of black smoke in the exhaust was found at the speed higher than 1,800 rpm in case of a diesel engine use. In order to extend the research and solve two foresaid problems, the objectives of this study were 1) to develop an auxiliary combustion chamber for cooling, 2) to develop a scalable gas-air mixing device, and 3) to compare diesel and LPG consumption rates, by modifying a small diesel engine, Yanmar version TF120DI to install LPG fuel systems and ignition system. In addition, a gas-air mixing device was modified while an auxiliary combustion chamber was developed to reduce the compression ratio to the same level as the gasoline engine for replacing the position of the original diesel fuel injector. This method could support LPG fueling only whose function was characterized by the function of a gasoline engine. The auxiliary combustion chamber could be removed and then installed a diesel injector to return using diesel fuel. From an experiment to compare the modified engine operating as a gasoline engine, it was found that the temperature of the auxiliary combustion chamber and the temperature of the engine cylinder head of Honda GX160 were measured at the maximum speed of 182 °C and 186 °C respectively. It was found that carbon monoxide content was 0.41 % and 1,315 ppm hydrocarbons. When used as a diesel engine, it was found that the black smoke was exhausted at 1.5 %, which was similar to the diesel engine before the modification. From the experiment of using the power engine for pumping water with an Irrigation propeller pump with the diameter of 8 inch at a constant engine speed of 1,000 rpm, it was found that the average diesel usage was 0.65 kg/hr or about 0.77 L/hr with the cost of 21.00 Baht/hr, and if using LPG as fuel, the average LPG consumption was 0.57 kg/hr with the cost of 13.71 Baht/hr, which could save up to 34.71 % of costs.