What is the reason why diesel engines emit white smoke?

Diesel engine exhaust emits diesel vapor (white) and water vapor (light white), which are collectively called white smoke. The reasons and elimination methods are as follows:

1, light white smoke: there is water in diesel oil.

Removal method: Drain the water from the bottom of fuel tank, diesel filter, fuel injection pump and other parts of diesel supply system.

Note: Diesel oil can only be used after it has settled for more than 24 hours. Do not insert the oil pump into the bottom of the diesel bucket when refueling. If the fuel tank cover is damaged or lost, it should be equipped in time. Cooling water leaks into the cylinder. Poor sealing of cylinder gasket or cracks at the bottom of cylinder head, cooling water in water jacket leaks into cylinder, which will also lead to white smoke of water vapor. Need to find the leaked parts and repair or replace the related parts.

2. White smoke: The temperature is low in winter. Due to the low temperature, some diesel oil failed to catch fire and emitted white smoke. This white smoke disappears automatically with the increase of engine temperature, which is a normal phenomenon and does not need to be eliminated. Poor atomization of diesel oil. The reasons are as follows: the fuel injection pressure is too low, the fuel injector drips seriously, or the fuel injector pressure adjustment is too low, which causes some diesel oil mist to fail to ignite in the combustion chamber and emit white smoke. Depending on the situation, either replace the plunger coupling of the oil pump, or adjust the injection pressure to a normal value, or remove the injector to grind and repair the needle valve coupling, or replace it if it cannot be repaired.

Extended data:

The advantages of diesel engine are high power and good economic performance. The working process of diesel engine has many similarities with that of gasoline engine, and each working cycle has to go through four strokes: intake, compression, work and exhaust. However, because the fuel used by diesel engine is diesel, its viscosity is higher than that of gasoline and it is not easy to evaporate, but its spontaneous combustion temperature is lower than that of gasoline, so the formation and ignition mode of combustible mixture are different from that of gasoline engine. The main difference is that the mixture in the cylinder of diesel engine is compression ignition, not ignition.

When the diesel engine is working, air enters the cylinder. When the air in the cylinder is compressed to the end, the temperature can reach 500-700℃ and the pressure can reach 40-50 atmospheres. When the piston approaches the top dead center, the high-pressure pump on the engine injects diesel into the cylinder at high pressure, and the diesel forms fine oil particles, which are mixed with high-pressure and high-temperature air. The diesel mixture burns itself and expands violently, generating explosive force and pushing the piston to do work downward. At this time, the temperature can reach 65,438+0,900-2,000℃ and the pressure can reach 60-65,438+0,000 atmospheric pressure, which generates a lot of power.

The advantages of diesel engine in energy saving and carbon dioxide emission are irreplaceable by all heat engines, including gasoline engines. Therefore, the emission of the advanced small high-speed diesel engine has reached the Euro III standard, and it has become a "green engine", which has now become the power device of many new cars in Europe and America.