Exergy-method analysis of a two-stage vapour-compression refrigeration-plants performance

The behaviour of two-stage compound compression-cycle, with flash intercooling, using refrigerant R22, has been investigated by the exergy method. The condenserʹs saturation-temperature was varied from 298 to 308 K and the evaporatorʹs saturation-temperature from 238 to 228 K. The effects of temperature changes in the condenser and evaporator on the plantʹs irreversibility rate were determined. The greater the temperature difference between either (i) the condenser and the environment, or (ii) the evaporator and the cold room, the higher the irreversibility rate. Any reduction in the irreversibility rate of the condenser gives approximately 2.40 times greater reduction in the irreversibility rate for the whole plant, and any reduction in the evaporatorʹs irreversibility rate gives a 2.87 times greater mean reduction in the irreversibility rate of the whole plant. Because the changes in the temperatures in the condenser and the evaporator contribute so significantly to the plantʹs overall irreversibility, there is considerable scope for optimising the conditions imposed upon the condenser and evaporator.