A new approach for cold thermal energy storages in supermarket refrigeration systems.

Supermarket refrigeration systems have a significant energy demand to preserve the quality of valuable food products. Thus, several approaches to reduce the energy demand, and to solve other challenges a supermarket refrigeration system faces have been considered in the past years. Some of the main challenges that have been addressed are the temperature instability of the food products in the display cabinets/freezers during defrost period. Other issues that have been considered are the high electricity network costs due to the grid dependency and peak power demand. One of the solutions proposed is the implementation of cold thermal storages (CTES) in combination with the widely applied CO2 refrigeration system of supermarkets. This paper proposes a new approach by implementing the cold storage on top of the display cabinet, and apply the thermosiphon principle for the heat exchange between the evaporator and the cold storage, when the cabinet is disconnected from the central CO2 refrigeration system. One of the advantages for this concept is the utilisation of currently unapplied space. Locating the CTES on top, it will not limit the size of the display cabinet, since normally, the space on top is not used for any other purposes and space in supermarkets is limited. Simulations at different boundary conditions will be conducted in order to assess the performance of this new concept.