Composition and working principle of automobile air conditioning and refrigeration system
1. Basic composition of automobile air conditioning and refrigeration system
The vapor shrinkage refrigeration system commonly used in modern automobile air conditioners is usually composed of a compressor, a condenser, a throttling device, a liquid dryer, an evaporator, and corresponding connecting pipes.
(1) The role of the compressor The compressor is the heart of the refrigeration system. It plays the role of pumping and compressing refrigerant and making it circulate continuously.
Suction: The suction when the compressor is working and the throttling effect of the throttling device cooperate to reduce the pressure of the refrigerant in the evaporator tube, complete the process of transforming from liquid to gas, and take away heat through the vaporization of the refrigerant Heat in the cabin.
Compression: When the compressor works, it compresses the low-pressure gaseous refrigerant to increase its pressure and temperature, and completes the process of converting from gaseous state to liquid state in the condenser, releases heat through liquefaction, and discharges the heat to the atmosphere outside the car.
Circulation pump: The compressor is the power source for the refrigerant circulation. The continuous suction and compression of the compressor makes the refrigerant circulate in the refrigeration system pipeline. Through the gas-liquid two-phase conversion during the refrigerant circulation process, the heat in the car is "moved" to the outside of the car. Refrigeration.
(2) The function of the condenser The condenser is a heat exchanger, which cools the high-temperature and high-pressure refrigerant vapor discharged from the compressor to convert it into a liquid refrigerant, and the heat released during the liquefaction process of the refrigerant through heat conduction and heat convection Distributed into the air outside the vehicle.
(3) The function of the throttling device The throttling device lowers the temperature and pressure of the liquid refrigerant output from the condenser through its throttling effect, so that the refrigerant sent to the evaporator can be completely vaporized and absorb more heat.
(4) The role of the liquid storage drier The liquid storage drier is used for filtration, dehumidification, gas-liquid separation and temporary storage of some refrigerants.
Shrinkage process: The compressor compresses the low-pressure, medium-temperature refrigerant vapor sucked from the evaporator into a high-pressure, high-temperature vapor and sends it to the condenser. The compression process makes the refrigerant vapor reach the pressure and temperature required for liquefaction. c Exothermic process: the high-pressure, high-temperature gaseous refrigerant condenses in the condenser, and performs heat exchange (heat release) with the air outside the car, and transforms into a high-temperature, high-temperature refrigerant. This process of high-pressure liquid refrigerant releases the heat in the refrigerant and transfers it to the air outside the car through the condenser.
Throttling process: The high-pressure liquid refrigerant flowing out of the condenser is dehumidified and filtered by the liquid storage drier, and then flows through the expansion valve, and is throttled and depressurized by the expansion valve and sent to the evaporator. The throttling process reduces the pressure and temperature of the refrigerant and produces a partial gaseous state
Refrigerant to ensure that the refrigerant can be completely vaporized in the evaporator.
Endothermic process: The low-pressure, low-temperature liquid refrigerant vaporizes (boils) in the evaporator, and performs heat exchange (endothermic) with the air in the car to become a low-resistance, medium-temperature gaseous refrigerant; absorbs heat in the evaporator The refrigerant vapor is sucked away by the compressor, so that the vaporization and heat absorption process of the refrigerant in the evaporator can continue.
The automotive air-conditioning refrigeration system uses refrigerant as the heat carrier. Through the continuous circulation of the above four processes, the heat inside the car is transferred to the outside of the car to achieve the air conditioning effect of cooling and dehumidification inside the car.
Requirements and types of automotive air-conditioning compressors In the process of understanding the working principle of the air-conditioning and refrigeration system, we have already known the role of the compressor. It is the power source of the refrigerant circulation in the refrigeration process of the refrigeration system and the "heart" of the refrigeration system. . Except for some passenger car air conditioners that use a specially configured auxiliary engine to drive the compressor, most of the air conditioner compressors are driven by the car engine. Compared with indoor air-conditioning compressors and refrigerator refrigeration compressors, the working environment and conditions of automotive air-conditioning compressors are much worse.