How does the engine start?
The exhaust of the diesel engine is basically the same as that of the gasoline engine, but the exhaust temperature is lower than that of the gasoline engine. General Tr=700 to 900K. For a single cylinder engine, its speed is uneven, the engine is not working smoothly, and the vibration is large. This is because there is only one stroke in the four stroke for work, and the other three strokes are the stroke that consumes power to prepare for the work done. To solve this problem, the flywheel must have a large enough moment of inertia, which in turn results in an increase in the overall mass and size of the engine. The use of multi cylinder engines can make up for these deficiencies. Modern cars use four cylinder, six cylinder and eight cylinder engines.
When a stroke is near the end of the compression stroke, in under the action of high pressure oil pump, diesel oil to about 10MPa by high pressure injector into the cylinder combustion chamber, in a very short period of time is mixed with the air immediately after self ignition combustion. The pressure of the gas in the cylinder rises rapidly, up to 5000~9 000kPa, and the maximum temperature is 1800~2 000K. Because the diesel engine is ignited by compression, it is called a compression ignition engine.
Compression stroke due to compressed refrigerant is pure air, so the compression of diesel engine is higher than gasoline engine (usually epsilon =16 to 22). The pressure at the end of compression is 3000~5 000kPa, and the temperature at the end of compression is 750~1 000K, greatly exceeding the autoignition temperature of diesel (about 520K).
Working process: air inlet compression injection combustion expansion work exhaust. Intake stroke, the working fluid into the cylinder is pure air. As the intake system of diesel engine has less resistance, the intake terminal pressure is pa= (0.85 to 0.95) P0, higher than that of gasoline engine. The inlet temperature is Ta=300 to 340K, lower than that of gasoline engine
