Annual energy analysis of a water-loop self-contained refrigeration plant and comparison with multiplex systems in supermarkets

• The layout of a real water-loop self-contained supermarket is presented.
• The seasonal supermarket performance is analyzed.
• A comparison with two traditional multiplex systems is presented.
• The best energy performance is obtained by the water-loop self-contained solution.
• The water-loop self-contained supermarket allows a reduction of CO2 emissions.

Supermarkets are probably the largest energy users in the commercial sector and are responsible for considerable CO2 emissions. In most cases, refrigeration systems employ direct expansion air refrigerant coils as evaporators in display cases and coolers. Compressors and condensers are kept in a remote machine room located in the back or on the roof of the store. As a consequence, a large amount of refrigerant is needed to charge the refrigeration system. Nowadays advanced supermarket systems can reduce both annual energy consumption and total equivalent warming impact (TEWI). One of these advanced solutions is the water-loop self-contained refrigeration system with modulating compressors (WLSC). In this paper a real WLSC supermarket located in Italy is considered and its annual performances are compared with those of both a simulated multiplex benchmark solution with thermostatic expansion valve (TEV) and fixed evaporation pressure and with those of a simulated multiplex solution with electronic expansion valve (EEV) and floating evaporation pressure.