Experimental investigation of a new CO2 refrigeration system arrangement for supermarket applications

A new position of an internal heat exchanger within the thermodynamic cycle is proposed to improve the performance of CO 2 refrigeration systems in warm climates, specifically in supermarket applications. The proposed configuration uses the saturated vapor from the liquid receiver to recover the heat that is rejected by a subcooler positioned after the gas cooler. This system results in a reduced evaporator superheat. This configuration is compared with a reference system. The experimental study is conducted on a CO 2 laboratory cooling system reproducing a commercial plant. The cooling capacity of the system is 30 kW. The water inlet temperature in the gas cooler (hot source) varies from 15 degrees C to 35 degrees C, while the mono -ethylene glycol outlet temperature of the evaporator (cold source) is fixed at -8 degrees C. The setup is validated through an energy balance. Using a subcooler in this new position improves the coefficient of performance by 10.2 % under transcritical conditions and 6.3 % under subcritical conditions when compared with the reference system.