The cooling system is needed for an engine since it helps to keep the engine at optimum temperature for the efficient working of the engine and to protect the engine components from the effect of overheating.
Due to the combustion process in the IC engine, the temperature of the engine reaches above the optimum temperature.
Thus cooling system provided to the IC engine carries away this excessive heat and keeps the engine at optimum temperature.
Why is a cooling system needed for an engine?
Following are some reasons for the necessity of engine cooling:
1) Avoid preignition in SI engine: In the case of the SI engine, the elevated engine temperature increases the temperature of the intake charge which causes preignition in SI engine.
2) Keep the engine components at optimum temperature: The cooling system carries away the un-useful heat and keeps the engine at the optimum temperature.
3) Protects from the failure of engine components: The gases in the combustion chamber reach a very high temperature that is nearer to the melting temperature of the material of the cylinder and cylinder head. Therefore it may result in failure in these components. The cooling provided to the engine helps to carry away this heat from the engine.
4) Prevent distortion in engine components: The temperature stresses arise due to the higher engine temperature causes the deformation in the components like a cylinder, cylinder head, etc. The engine cooling helps to lower these thermal stresses and lowers the distortion.
5) Increases the volumetric efficiency: The elevated temperature of the engine increases the temperature of the intake air and thus decreases the density. Due to the decrease in density, less amount of charge is fed into the engine. Hence the volumetric efficiency of the engine decreases. Therefore to increase the volumetric efficiency, the engine requires cooling.
6) Reduces the piston seizure: Due to the increase in temperature, the oil film present between the piston and cylinder gets oxidized. Therefore due to the lack of lubrication film and the presence of carbon deposition causes the metal to metal contact between piston, piston rings, and cylinder liner and therefore this results in piston seizure.
These are the some reasons that state the importance of the engine cooling system.