The compression ignition engine is a diesel engine used in heavy vehicles, machinery, railways, ships, trucks, and equipment. In the combustion process, unlike the SI engine, only air enters the cylinder during the suction stroke, which allows both air and fuel to enter. It ignites diesel fuel with compressed hot air. CI engine is also internal combustion engines that use diesel fuel to run on a diesel cycle.
In the system, the spark plug is terminated because the spark does not require combustion. The combustion is accomplished by compressing the air purified in the cylinder, which is then compressed to a warm temperature to ignite when the fuel is injected. This system has a high compression ratio due to the high ignition temperature of diesel fuel.
Higher compression ratios produce more power. Incomplete combustion produces more hydrocarbons, causing air pollution from the exhaust. The first phase (intake) begins by opening the suction valve. The clip moves from TDC to BDC, causing the pressure in the cylinder to rise as the volume increases above the piston so that the actual cylinder pressure is 0.7 - 0.85 bar during the suction time. In the case of the turbocharged engine, it is up to 2 times.
The second stroke (compressions) begins by closing the suction valve & ends at TDC. The capacity of the injected working medium in the compression chamber is reduced by 14 to 24 times. The air pressure at the end of compression is 30 - 60 bar, and its temperature is 600 - 9000C. After compression of air, expansion begins, and fuel is injected into the cylinder with pressures of 90 - 2000 bar, depending on injection devices.
The fuel is dispersed, heated, mixed with air, & ignites. During combustion, the temperatures rise to 2000 - 25000C & the pressure to 60 - 120 bar. In this trick, the piston mechanism has maximum mechanical and thermal stresses. During expansion, the clip is changed from BDC to TDC, thus the clearance of the cylinder through the exhaust valve. The pressure at which exhaust gases pass is 1.05 to 1.20 bar. The temperature of the gases is 500 - 6000C.