Cooling and heating modes of direct-expansion air conditioning units.
The direct-expansion air conditioning unit system is an all-air system. The entire air conditioning system is only composed of outdoor units and indoor units. It does not need water pumps, cooling towers, fan coils and other supporting equipment, nor does it need condensate drainage pipes. It is extremely convenient to install and use. There is no movement machinery and water pipe in the system room, so users need not worry about noise and water leakage, and maintenance is convenient. The unit is placed on the roof or outdoor open space, without machine room, saving initial investment. The unit does not need secondary refrigerant, and the system efficiency is high. The direct-expansion air conditioning unit has full functions, which can easily realize air purification, dehumidification, humidification, cooling, heating, fresh air volume adjustment and other functions. The direct-expansion air conditioning unit is applicable not only to shopping malls, restaurants, entertainment, office buildings, guilds and general industrial workshops, but also to clean places in industrial workshops such as medicine, food, electronics, chemicals, scientific research and machinery.
Operating principle of direct-expansion air conditioning unit:
Cooling mode:
The outdoor side finned heat exchanger is used as the condenser, and the indoor side finned heat exchanger is used as the evaporator. The refrigerant high temperature gas discharged by the compressor is condensed into liquid in the outdoor side finned heat exchanger, then throttled and depressurized by the expansion valve to form a low-temperature gas-liquid mixture, and then flows into the indoor side finned heat exchanger, absorbs the heat and evaporates, and then returns to the compressor to complete a refrigeration cycle; At the same time, the return air (or fresh air) from the room is cooled after passing through the indoor side fin heat exchanger (now evaporator), and the treated cold air is sent into the room by the indoor side fan.
Heating mode:
The outdoor finned heat exchanger is used as the evaporator, and the indoor finned heat exchanger is used as the condenser. The refrigerant high temperature gas discharged by the compressor is condensed into liquid in the indoor finned heat exchanger, then throttled and depressurized by the expansion valve to become a mixture of low temperature gas, and then flows into the outdoor finned heat exchanger to absorb heat and evaporate, and then returns to the compressor. The direct-expansion air conditioning unit completes a refrigeration cycle; At the same time, the return air (or fresh air) from the room is heated up after passing through the indoor side fin heat exchanger (now the condenser), and the treated hot air is sent into the room by the indoor side fan.
Six units with 16000 air volume direct-expansion, cooling capacity 300KW, heating capacity 320KW, fan frequency conversion, PLC control. The service is installed in Dalian, Liaoning Province.
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