There are several types of high-precision constant temperature and humidity air conditioners for computer rooms: air-cooled, water-cooled, dual-cold source and free cooling. For the refrigeration of high-precision constant temperature and humidity air conditioners, no matter which of the above, heat is absorbed from the outside or released to the outside through the change of the state of the refrigerant in the high-precision constant temperature and humidity air conditioner. Unless the components or copper tubes of the high-precision constant temperature and humidity air conditioner leak, the refrigerant is in a closed environment, and the refrigerant circulates between the compressor, condenser, pressure expansion valve, fan and copper tube, while changing the state of the refrigerant itself, that is, gas changes to liquid, and liquid changes to gas. This is the so-called internal circulation.
1. Air-cooled high-precision constant temperature and humidity air conditioner for computer rooms
    is air-cooled, that is, the refrigerant of the air conditioner is cooled by wind, and the condenser installed outdoors (precision air conditioner outdoor unit) takes away the heat of the condenser and makes the refrigerant release heat. Air-cooled condensers are mainly composed of several groups of copper tubes and fans. Since the heat transfer performance of air is very poor, fins are usually added to the outside of the copper tubes to increase the heat transfer area on the air side. At the same time, fans are used to accelerate air flow and increase the heat dissipation effect. The speed of the fan can be constant, adjustable, or constant + adjustable.
2. Water-cooled machine room high-precision constant temperature and
    humidity air conditioner The structure of the water-cooled machine room precision air conditioner is not much different from the air-cooled type. The main difference is: the water-cooled machine room precision air conditioner is equipped with a water-cooled plate condenser in the indoor unit (compared with the air-cooled precision air conditioner, the internal circulation of the refrigerant is only in the indoor unit, and the working pressure of the compressor is much smaller). The refrigerant releases heat when passing through the water-cooled plate condenser, and the cold water of the water-cooled plate condenser absorbs heat and is discharged to the building cooling tower through a water pump (generally installed outside the precision air conditioner), and then the cooling tower discharges the heat into the air. Since the cooling tower is a heat and moisture exchange device (air and water are in direct contact), the cooling effect is good.
3. Free cooling
    This type of machine is mainly used in cold areas in the north, and can also be regarded as a water-cooled machine room high-precision constant temperature and humidity air conditioner. Once the outdoor temperature is below 0℃, add ethanol solution to the water (to ensure that the water does not freeze) to ensure that the cooling water does not freeze. Unlike general water-cooled machine room precision air conditioners, free cooling machine room precision air conditioners install dry cooling towers outdoors, which are similar to the air-cooled machine room precision air conditioners, except that the substances in the pipes are different. The former is hot water and the latter is a high-temperature condensing agent.
4. Chilled water refrigeration
    The premise of setting up a chilled water machine room precision air conditioner is to have chilled water. You can use the chilled water of the central air conditioner, or build a new chilled water system. The
    indoor unit of the chilled water machine room high-precision constant temperature and humidity air conditioner is mainly composed of chilled water coils, fans, electric heaters, humidifiers and water valves. Generally, there is no compression refrigeration system. Therefore, the initial investment of this model is relatively small, but it relies on chilled water. If the chilled water cannot be supplied, the system will be paralyzed. Therefore, there is the following dual cold source system.
5. Dual cold source system
    The dual cold source system is to ensure the refrigeration security of the high-precision constant temperature and humidity air conditioning in the computer room, and at the same time make full use of the chilled water of the central air conditioning in the building. The dual cold source computer room high-precision constant temperature and humidity air conditioning can be used. There are two combinations:
1. Air-cooled condensation + chilled water, with the chilled water system as the main use and the air cooling system as the backup.
2. Water-cooled condensation + chilled water, with the chilled water system as the main use and the water cooling system as the backup.