Experimental tests on a dual fuel compression-ignition engine powered by biogas with a varying chemical composition

Biogas is among the fuels whose significance in the general energy balance will increase. These results from the fact that it may be produced from various kinds of waste materials, and it is therefore considered a renewable fuel of the second generation. Because of its properties, biogas may be used directly to power spark-ignition engines. Nonetheless, numerous tests are underway involving the possibility of using biogas to power compression-ignition engines. In order to use biogas, whose main combustible component is methane, in compression-ignition engines, it is necessary to use a dual fuel power supply system. With such a system supplying power to the engine, the gas and air mixture in the cylinder is ignited by a small dose of liquid fuel. This paper presents a fragment of the research on the use of biogas with a varying chemical composition for powering compression-ignition engines. The described tests were conducted using a one-cylinder compressionignition engine mounted on an engine test stand. The fuel gas consisted of a mixture of natural gas and carbon dioxide; the share of each individual component was regulated from the station, which controlled the operation of the whole test stand. The developed control system also enabled the adjustment of the operating parameters of the engine test stand and the parameters of the injection of liquid fuel, such as the injection pressure, the timing angle of injection and the size of the dose. The results presented in the paper show the impact of the individual control parameters of the engine on the value of the engine’s torque and the amount of toxic compounds in the exhaust fumes.