They work differently, and that's what differentiates them.
1. The working principle of fuel engine
Let's take a single-cylinder gasoline engine as an example to explain the working principle of a fuel engine.
The cylinder is equipped with a piston, which is connected to the crankshaft by piston pins and connecting rods. The piston reciprocates in the cylinder and rotates the crankshaft through the connecting rod. In order to draw in fresh gases and exhaust gases, intake and exhaust valves are provided.
The farthest point of the piston top from the center of the crankshaft, that is, the highest position of the piston, is called the top dead center. The closest point to the center of the crankshaft at the top of the piston, the lowest position of the piston, is called the bottom dead center.
The distance between the top and bottom dead centers is called the piston stroke, and the distance from the center of connection between the crankshaft and the lower end of the connecting rod to the center of the crankshaft is called the crankshaft radius. Each stroke of the piston corresponds to a crankshaft angle of 180°.
For engines with the cylinder centerline passing through the crankshaft centerline, the piston stroke is equal to twice the crank radius.
The volume swept by the piston from top dead center to bottom dead center is called the working volume of the engine or engine displacement, and is represented by the symbol VL.
The duty cycle of a four-stroke engine consists of four piston strokes, namely the intake stroke, the compression stroke, the expansion stroke (work stroke) and the exhaust stroke.
2. The working principle of the gas engine:
LNG enters the vaporizer from the gas cylinder through the pipeline for heating and vaporization, and after the pressure stabilization tank is stabilized, it is filtered by the gas regulator and then by the gas filter, and then it can be controlled by the solenoid shut-off valve to enter the regulator for stabilization, and the stabilized gas enters the heat exchanger.
The CNG enters the pressure reducer from the compressed gas cylinder through the pipeline to 8 bar and then enters the heat exchanger through the filter.
After being heated by a heat exchanger, the gas enters the FMV through the thermostat, and is injected into the mixer controlled by the FMV to mix with the pressurized air. The electronic throttle controls the mixture to enter the engine cylinder to do the work.
The LPG comes out of the gas cylinder and passes through the high-pressure solenoid valve to the evaporation pressure regulator to become gaseous LPG. The LPG is fully mixed with air in the mixer through FTV and enters the engine cylinder for mixed combustion.
The most fundamental difference is that the engine is different, and its working principle is very different, the diesel engine is compression-ignition type with an ignition point of 220 °C, the gasoline engine is ignited type with an ignition point of 427 °C, and the natural gas engine is ignited type with an ignition point of 650 °C.
Fuel engines (such as automobiles) are piston-driven, cylinder-driven. A gas engine (thermal power generation) is a gas injection onto a turbine that drives the rotation.
The biggest advantage of gas engines is that they have low emission pollution, natural gas engines will not cause lubricating oil dilution, can prolong engine life, and can also reduce car noise.
However, there are still some problems in the use of gas-engine vehicles, the most prominent of which are the problem of engine power decline, engine corrosion and early wear.
The decrease in the power of natural gas vehicles is due to the decrease in the inflation coefficient and the low compression ratio of the engine, and the early wear of the engine is due to the presence of trace sulfides in the natural gas.