The Development History of Computer Room Refrigeration-Chemical Instrument Network

1、 Change in refrigerant state
1. Water is also a type of refrigerant, and the refrigeration cycle utilizes the enormous amount of heat that needs to be absorbed or released during the phase transition of substances. This is because under normal pressure, the saturation temperature is higher and cannot absorb the indoor heat at normal temperatures, so it is not commonly used.
2. R22, at normal pressure (70PSIG), has an evaporation temperature of (4.5 ℃) and strong refrigeration capacity per unit solvent, making it an ideal cooling source for the ideal comfortable temperature range of 21-27 ℃ for humans.
3. Similar in nature, for R22, at a pressure of (70PSIG), the saturation temperature is (4.5 ℃). Therefore, the refrigerant temperature during the evaporation process at this pressure remains constant at (4.5 ℃), and the evaporation process is first in a saturated liquid state. At a pressure of (70PSIG), if the temperature of R22 is below 4.5 ℃, it must be at a temperature below the saturation point, and we call it a supercooled liquid. If the temperature of R22 is higher than 4.5 ℃, it must be in a gaseous state and the temperature is higher than the saturation point, which we call superheated gas.
4. To achieve condensation and heat dissipation of refrigerant on the relatively high temperature side of the condenser, the only way is to increase the pressure of the refrigerant to raise its saturation temperature, making it higher than the outdoor ambient temperature, thus achieving the process of heat dissipation and condensation.
2、 Cooling capacity andrefrigeration cycle
1. Cooling cannot be produced, its essence is the transfer of heat. The refrigeration cycle is the process of transferring heat from an air-conditioned room to another space that can accommodate and dilute this portion of heat. To achieve this part of the cycle, a certain amount of work is required, and this heat transfer process is periodically repeated within a closed system.
The endothermic and exothermic processes utilize the endothermic and exothermic characteristics corresponding to the phase change of a fluid at different saturation temperatures under different pressures (the enthalpy of the fluid changes, and the heat transfer during the phase change process is significant compared to just temperature changes).
2. The refrigeration cycle (saturated vapor compression refrigeration cycle) is based on the basic principle of the reverse Carnot cycle, which utilizes a compressor and halogen derived refrigerants (saturated vapor state) or organic/inorganic compounds. The use of a compressor to increase the pressure of gaseous refrigerant is called vapor compression refrigeration.
The range of refrigerants that can be used in this refrigeration cycle is very wide, and intermediate refrigeration can be achieved based on the combined electrical characteristics. The compression technology currently used in the market is achieved through this cycle, which is also the refrigeration cycle currently used worldwide, using the vast majority of models from different manufacturers.
3、 A Brief History of Refrigeration Development
In 1800, people discovered that the mixture of ice/snow and salt had a cooling effect, which could significantly reduce water temperature and cause water to freeze.
In 1834, the British man Perkins made the first compression refrigeration machine that used ether as a refrigerant.
In 1873, German inventor Lin Jie invented the ammonia refrigeration machine.
In 1876, methyl ether was used as a refrigerant for transporting meat from Argentina to France.
At the end of the 19th century, with the continuous maturity of mechanical refrigeration technology, a large number of applicable refrigerants such as ammonia, carbon dioxide, sulfur dioxide, chloromethane, and hydrocarbons were produced.
At the beginning of the 20th century, Start refrigeration technology began to enter industrial applications, and at that time, most of the developed refrigerants had high working pressures and were toxic and flammable.
In 1928, a new type of refrigerant (dichlorodifluoromethane) was successfully synthesized in the United States. It is non flammable, has low toxicity, and has low working pressure, making it an ideal refrigerant that people expect.
In 1931, DuPont began large-scale industrial production of this newly synthesized refrigerant, giving birth to the Freon family.
From 1930 to 1950, the refrigerant family and large commercial air conditioners experienced rapid development.
In 1988, the Montreal Protocol reached an agreement among the contracting parties to restrict the use of refrigerants that have a destructive effect on the atmospheric ozone layer and set a specific timetable for action.