(1) The temperature of the exhaust gas from the engine is very high, and the temperature of the intake air will be increased through the heat conduction of the supercharger. In addition, the density of air will increase in the process of being compressed, which will also lead to the increase of air temperature discharged from the supercharger. With the increase of air pressure, the oxygen density will decrease, thus affecting the effective charging efficiency of the engine. If we want to improve the inflation efficiency further, we need to reduce the intake temperature. Data show that under the same air-fuel ratio, the engine power can be increased by 3% ~ 5% for every 10 ℃ decrease in the temperature of pressurized air.
(2) If the uncooled pressurized air enters the combustion chamber, it will not only affect the aeration efficiency of the engine, but also easily lead to excessive combustion temperature of the engine, causing detonation and other faults, and increase the content of NOx in the exhaust gas of the engine, causing air pollution.
In order to solve the adverse effects caused by the air heating after pressurization, it is necessary to add an intercooler to reduce the intake temperature.
(3) Reduce engine fuel consumption.
(4) Improve the adaptability to altitude. In the high altitude area, adopting the medium cooling can use the compressor with higher pressure ratio, which makes the engine get more power and improves the adaptability of the car.
(5) Improve the matching and adaptability of supercharger.
