The Structure and Working Principle of Automobile Air Conditioning System
Automobile air conditioners are generally mainly composed of compressors, electronically controlled clutches, condensers, evaporators, expansion valves, liquid storage dryers, pipelines, condensing fans, vacuum solenoid valves, idlers and control systems. Automobile air conditioners are divided into high-pressure pipelines and low-pressure pipelines. The high-pressure side includes the compressor output side, high-pressure pipeline, condenser, liquid storage dryer and liquid pipeline; the low-pressure side includes the evaporator, accumulator, return pipeline, and compressor input side.
Compressor
The function of the compressor is to increase the pressure of the refrigerant, causing it to liquefy and release heat in the condenser, and as a power source to promote the circulation of the refrigerant within the system. It is the heart of the air conditioning system.
Refrigerant
Currently, there are two types of refrigerants used in most cars: R-12 refrigerant and R-134a refrigerant. R-12 refrigerant is a common refrigerant that contains Freon, a substance that can destroy the ozone layer, and can produce substances harmful to the human body under open flames; R-134a is a new type of environmentally friendly refrigerant that is non-toxic and non-toxic. Color, non-flammable, non-explosive, and good thermal stability. More importantly, R-134a refrigerant does not damage the ozone layer.
Condenser
The function of the condenser is to cool the high-temperature and high-pressure gas refrigerant into high-temperature and high-pressure liquid refrigerant.
Liquid storage dryer
The function of the liquid storage dryer is to filter the moisture and impurities in the refrigerant, store the refrigerant, and ensure that the refrigerator is continuously delivered to the expansion valve.
Air conditioning ducts
Air conditioning pipes: Since a certain pressure of refrigerant needs to be injected, metal pipes must be used. Especially the section from the compactor to the condenser to the refrigerant bottle to the expansion tube has higher pressure resistance requirements than other pipelines because it is the high-pressure section of the system.
Expansion valve
The function of the expansion valve is to convert high-temperature and high-pressure liquid refrigerant into low-temperature and low-pressure liquid refrigerant through throttling.
Evaporator
The low-temperature and low-pressure liquid refrigerant absorbs heat in the evaporator, undergoes heat exchange, and turns into a low-temperature and low-pressure gaseous refrigerant.
Blower
The blower continuously blows the cooled air into the cabin.
Working principle of automobile air conditioning and refrigeration system
When the compressor is working, the compressor injects the low-temperature and low-pressure gaseous refrigerant from the evaporator. After compression, the temperature and pressure of the refrigerant increase, and it is sent to the condenser. In the condenser, the high-temperature and high-pressure gaseous refrigerant transfers heat to the outside air passing through the condenser and liquefies it, turning it into a liquid. As the liquid refrigerant flows through the throttling device, its temperature and pressure decrease and enters the evaporator. In the evaporator, the low-temperature and low-pressure liquid refrigerant absorbs the heat of the air in the car passing through the evaporator and evaporates, turning into a gas. The gas is sucked into the compressor for the next cycle.
The refrigerant circulates continuously in the system. Each cycle includes four processes: compression process, condensation process, throttling process, and evaporation process.
1. Compression process:
The compressor sucks in the low-temperature and low-pressure refrigerant gas at the outlet of the evaporator, compresses it into high-temperature and high-pressure gas, and discharges it from the compressor
2. Heat release (condensation) process:
The superheated refrigerant gas with high temperature and high pressure enters the condenser. Due to the reduction in pressure and temperature, the refrigerant gas condenses into a liquid and releases a large amount of heat.
3.Throttling process:
The refrigerant liquid with higher temperature and pressure becomes larger in volume after passing through the expansion device, the pressure and temperature drop sharply, and is discharged from the expansion device in the form of mist (fine droplets)
4. Evaporation (endothermic) process:
The mist refrigerant liquid enters the evaporator, so the boiling point of the refrigerant is much lower than the temperature inside the evaporator, so the refrigerant liquid evaporates into gas.
During the evaporation process, a large amount of surrounding heat is absorbed, and then the low-temperature and low-pressure refrigerant vapor enters the compressor. By continuing the above process over and over, the purpose of reducing the air temperature around the evaporator can be achieved.
