Energy performance of a CO 2 transcritical refrigerating plant with a thermoelectric subcooler system.

The subcooling technique is a well-known method that improves the energy performance of CO2 transcritical refrigeration cycles, being the suction-to-liquid heat exchanger a widely used example of this technique. Among all methods which provide subcooling, thermoelectric subcooling has been highlighted as one of the most incipient methods for standalone systems due to its robustness, compacity, durability and low-cost implementation. Taking into account the promising results from a previous computational analysis, the aim of this work is to experimentally analyse the results of including a thermoelectric subcooler in a small-capacity CO2 refrigerating plant. Tests were conducted at two ambient temperatures of 25 and 30oC, maintaining a constant evaporating temperature of -10oC. Varying the voltage supply to the thermoelectric modules and the heat rejection pressure, the experimental results provided a maximum increment of COP and cooling capacity of 9.9% and 16.0%, respectively, at the optimum voltage supply of 2 VDC.