Coolant is sucked by the compressor through the suction line under low pressure and temperature (Example: for R22 evaporation temperature 6 ° C the pressure would be 73 psig), being compressed, thus raising the temperature (reaching about 90 ° C), this fluid in the gas phase flows to the condenser through the discharge line which is exposed to the external medium.
With the difference in temperature between the discharged vapor and the air from the external environment, the release of sensible heat occurs, consequently its temperature will decrease until the condensation temperature reaches 10 to 15 ° C above the external ambient temperature. The fluid condenses by the release of latent condensation heat, under constant temperature and pressure, and flows to the expansion device located in the condensing unit.
The expansion device, which may be at the outlet of the condensing unit or at the evaporator unit inlet, causes a pressure drop in the liquid refrigerant fluid to enter the evaporator under low pressure and in the process of changing the liquid phase to the ie with the pressure drop the fluid passes from the liquid phase to the gaseous phase absorbing latent heat of vaporization under constant pressure and temperature, generally 5 ° to 7 ° C.
After the vaporization process the fluid exits the evaporator still with temperature below the external ambient temperature and follows through the suction line absorbing heat, it is said the fluid is overheating.
The superheated fluid is sucked out by the compressor and starts the cycle again.
