The wide application of refrigeration and air-conditioning technology in daily life, industry, and commerce, as well as medical, agricultural, fishing, mining, and other industries, are numerous and occupy an important weight.
Due to the continuous economic growth, the increasingly prosperous society, the improvement of people's living standards, and the narrowing of the gap between the rich and the poor. Not only do households have refrigerators, but most factories, offices, and homes are equipped with air conditioners, and various refrigeration and air-conditioning equipment and continue to introduce new ones to promote the rise of the refrigeration and air-conditioning industry.
Definition of refrigeration and air conditioning:
Refrigeration: It is an industry that manufactures items lower than the outside temperature to keep items for a long time, including freezing, refrigeration, freezing, rapid freezing, and ultra-low temperature engineering.
Air Conditioning: It is to deal with the temperature, humidity, clean air distribution, and noise of the air, and creates a comfortable environment suitable for human life and work.
Basic principles:
The basic principle of refrigeration and air conditioning: refrigeration and air conditioning system includes a refrigerant compressor, condenser, expansion valve, and evaporator, any mechanical refrigeration system must have these four elements.
Scope of work:
The scope of work of a refrigeration and air-conditioning technician includes:
- Manufacture, install, and maintenance of household refrigeration and air conditioners such as refrigerators, freezers, freezers, and window air conditioners.
- Manufacturing, installation, repair, and maintenance of commercial refrigeration and air-conditioning projects such as box-type air conditioners, refrigerators, freezers, heating, dehumidification, and humidification.
- Manufacturing, installation, repair, and maintenance of industrial central refrigeration and air-conditioning systems and other related machines.
Basic Theory of Air Conditioning Equipment - Refrigeration Cycle System
The main medium: Refrigerant
Refrigerant characteristics: It is easy to dissipate heat and cool to a liquid state when it is in a high-pressure gas state, and it is easy to absorb heat and evaporate into a gas state when it is in a low-pressure liquid state.
It is gaseous at room temperature and becomes liquid due to the pressure in the tube, and cold coal changes from gaseous to liquid, which is called liquefaction. It will emit a large amount of latent heat of liquefaction, resulting in a warming effect. The change from liquid to gas, called evaporation, will absorb a large amount of latent heat of evaporation, resulting in a freezing effect.
The cycle process and four components of the mechanical refrigeration system:
- Compressor: Compress the gaseous refrigerant to promote the circulation of the refrigerant in the system, so that the low-pressure and low-temperature gaseous refrigerant becomes a high-pressure and high-temperature gaseous state after being compressed. The main reason why the refrigerant compressor compresses the refrigerant into high pressure is to promote the circulation of the refrigerant and the two purposes of heat dissipation and liquefaction under high pressure. When the volume is constant, the temperature rises and the pressure rises. After compressing the refrigerant, the density increases, and the high temperature and high-pressure change will cause the airflow to move naturally to the low temperature and low pressure. When the compressor is abnormal, the speed will drop, the exhaust volume will become smaller, and the refrigeration capacity will decrease.
- Condenser: Also known as a condenser or a radiator, the high-pressure high-temperature refrigerant after compression is used for cooling by the heat dissipation of water and air, and the liquid refrigerant at high pressure and room temperature is cooled, and the window-type air conditioner is placed outside the house. Window-type air conditioners use fans to force air and use air for heat exchange. Water-cooled air conditioners use cooling water for heat exchange, while refrigerators use natural wind for heat exchange. If the condenser is in poor condition, it will cause poor heat dissipation and cause excessive pressure.
- Refrigerant controller: Including capillary or expansion valves (refrigerator system), many kinds. The main function is to reduce the pressure and adjust the flow. The diameter becomes smaller, the flow rate becomes larger, but the pressure is still the same, and there will be wear and tear. After this process, the refrigerant will be a liquid-gas refrigerant with low temperature and low pressure.
- After the capillary or expansion valve is connected back to the original pipeline, it will achieve the function of complete depressurization.
- If the distance of this device is extended, more refrigerant must be added, the burden on the compressor will be heavier, and the service life will be shorter.
- The expansion valve will be opened and closed according to the size of the cooling air load. The cooling room load is large, the refrigerant moves quickly, the amount of refrigerant passing through is large, and the expansion valve needs to be opened. When the amount of refrigerant used is small, too much refrigerant will be temporarily stored in the receiver.
- The evaporator sprays the low-temperature and low-pressure mist refrigerant after capillary pressure reduction and throttling into the evaporator to absorb the latent heat of evaporation. It cools the refrigerant at the same time. Cools and dehumidifies the air circulating through the evaporator. This part is the air outlet of the indoor unit.
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