Abstract
In regions with a continental climate, refrigerators with air-cooled condensers operate at high condensation pressures during the summer season which reduces their efficiency and accelerates the wear of compressors. To reduce condensation pressure, it was proposed to use radiative cooling which is a way of heat removal through the planet's atmosphere to outer space in a form of infrared radiation. A refrigerating machine with an assembly of condensation heat removal including air and liquid cooling condensers connected in series has been developed. To reduce the condensation temperature, a pre-cooled heat-transfer agent is fed to the liquid cooling condenser during the day hours at high atmospheric temperatures. At night, the heat-transfer agent is cooled by radiative cooling. An experimental study of the operation of a 600 W refrigerating machine including a sealed piston compressor was conducted. R134a refrigerant was used. Supply of pre-cooled heat-transfer agent at +33.1 °С has provided a reduction of condensation temperature from +47.0 to +39.1 °С. The study was conducted at an atmospheric air temperature of +38.0 °С. The degree of pressure growth was decreased by 30 %. The refrigeration coefficient was increased by 11 %. In comparison with the conventional scheme with an air-cooled condenser, energy consumption by the system did not change in the daytime. The offered scheme of condensation heat removal reduces the pressure of condensation and provides stability for refrigerating machine operation. It can be used in stationary refrigerating machines at high daytime temperatures.
Highlights
In vapor-compression refrigerating machines (VCRM), heat from the cooled object is removed to the environment through a condenser
If the heat of condensation is removed to atmospheric air, the refrigerant condensation temperature rises to +50...+60 °С
In the case of using air-cooled condensers (ACC), the condensation pressure of refrigerants increases with an increase in the temperature of atmospheric air since the condensation temperature in them must be 10 to 20 K higher than ambient temperature
Summary
In vapor-compression refrigerating machines (VCRM), heat from the cooled object is removed to the environment through a condenser. If the heat of condensation is removed to atmospheric air, the refrigerant condensation temperature rises to +50...+60 °С. In the case of using ACC, the condensation pressure of refrigerants increases with an increase in the temperature of atmospheric air since the condensation temperature in them must be 10 to 20 K higher than ambient temperature. This limits their use in regions where there is a shortage of freshwater. The use of such condensers is not always possible in regions where water resources are limited To solve these problems, it is proposed to consider the possibility of removing condensation heat through radiative cooling (RC). Studies aimed at using radiative cooling to remove condensation heat can be considered relevant
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