The structure of a gas engine is similar to that of a gasoline engine, and it is divided into a diesel gas engine and a spark ignition gas engine according to the ignition mode of the mixture. Diesel gas engine uses coal gas as the main fuel. Gas and air are mixed through the mixing chamber and then enter the cylinder. When the piston approaches the top dead center of the compression stroke, a small amount of diesel is injected as a pilot fuel to ignite the mixture. Therefore it is also a dual-fuel engine. The amount of pilot fuel is calculated by heat, which is equivalent to 5-15% of the total heat consumption when the gas generator is operating at full load. The amount of pilot fuel is generally unchanged when the load changes. The spark-ignition gas generator uses electric sparks to ignite the mixture when the piston is close to the top dead center of the compression stroke. This type of gas generator basically works according to the Otto cycle.
