High temperature refrigeration in high and low temperature test chamber

High temperature refrigeration of high and low temperature test chamber mainly depends on refrigeration cycle and binary cascade refrigeration system. The refrigeration cycle adopts the inverse Carro cycle, which consists of two isothermal processes and two adiabatic processes. The specific process includes:
The refrigerant is adiabatic compressed to a higher pressure by the compressor, and the work consumed increases the exhaust temperature, and then the refrigerant is thermally exchanged with the surrounding medium through the condenser to transfer heat to the surrounding medium.
Then the refrigerant expands adiabatically through the closure valve to do work, and the temperature of the refrigerant decreases. Finally, the refrigerant absorbs heat from the higher temperature object isothermal through the evaporator, so that the temperature of the cooled object is reduced. This cycle is repeated to achieve the purpose of cooling.

In order to meet the requirements of the temperature reduction rate and very low temperature of the high and low temperature test chamber, a cascade refrigeration unit composed of imported refrigeration compressors is generally used. The refrigeration unit has the advantages of effective pairing, high reliability, convenient application and maintenance. At the same time, the design scheme of the high and low temperature test box refrigeration unit uses the kinetic energy adjustment technology, and can reasonably adjust the energy consumption and air conditioning cooling capacity of the refrigeration unit under the normal operation of the refrigeration unit, so that the operation cost of the refrigeration unit can be reduced to a more economic development situation.
In addition, R404A can also be used as a refrigerant. R404A is a low-temperature refrigerant for cascade refrigeration system with a standard boiling point of 46.6℃. R125(standard boiling point of -49℃), R143a(standard boiling point of -47.2℃) and R134a(standard boiling point of -26.1℃) are mixed according to the mass fraction of 44:52:4, and the thermal physical properties are similar to R22. But R404A is non-toxic and does not damage the ozone layer.