How diesel engine works

How diesel engine works ? 

1. Diesel engine brief  description.
   

   Liquid or gaseous fuel is mixed with air and fed directly into the machine to generate heat by burning inside, converting heat energy into mechanical energy.

   2. Diesel engine Features.

     Small volume, light weight, easy to move, high thermal efficiency, good starting performance, stable work, etc.

   3.Diesel engine working principle

    The work of the internal combustion engine is completed by the four processes of intake, compression, work and exhaust,           which constitute a work cycle. The piston goes through four processes to complete a work cycle. Called four-stroke

    1) Intake air 

    The air entering the cylinder is pure air (natural gas).The intake system has open intake valves and low intake resistance

     The residual exhaust gas temperature is low, so with the gasoline engine.Than, the cylinder pressure at the end of the intake is       slightly higher, about 0.08~0.095MPa.

 

    2)Compression process

     Diesel engine compression is relatively large, the compression ratio is very high, single-cylinder air-cooled diesel engine       between 19 to 21Compression end of the cylinder gas pressure is about 3 to 5MPa, the temperature is about 750K ~ 950K.   (1K = -272 ℃)

    3)Work process

     Diesel fuel is injected into the combustion chamber by the injector under the high pressure of 10-20MPa and mixed rapidly      with the air compressed by the moving piston to form a combustible mixture.

The temperature inside the cylinder is higher than the self-ignition temperature of diesel fuel, and the diesel fuel ignites and burns on its own.The highest combustion pressure of gas can reach 6~9MPa, and the highest combustion temperature reaches 1800~2200K.

      4) Exhaust process

      The gas pressure at the end of operation is about 0.3MPa, the temperature is about 1000 ~ 1200K.At the end of exhaust, the           residual exhaust gas pressure in the cylinder is about 0.105～0.12MPa, and the temperature is about 700～900K.

4. Diesel  engine advantages. 

(1) diesel engine than gasoline engines to save fuel, better economy of use. As the diesel engine compression is larger than the gasoline engine, so the gas expansion is more adequate, high thermal efficiency.

(2) diesel engine without ignition system, reliable work, easy maintenance, gasoline engine auxiliary electrical components, maintenance complex.

(3) diesel engine and the same power compared to the gasoline engine, its volume is larger, the mass is also large, and the operation of the noise is also greater. Because of the higher pressure in the cylinder of diesel engines, the body is under great stress, high rigidity strength requirements.

(4) diesel engine is more difficult to start. Because of the temperature of the air at the end of the compression to make the diesel fuel self ignition combustion.

(5) because the gasoline is more flammable and explosive, so the diesel engine is more widely used.

 5.  Diesel engine  structure

 6.Diesel engine widely using area.