Cold thermal energy storage for air conditioning in a supermarket CO2 booster refrigeration system

Integrated supermarket refrigeration systems are based on transcritical CO2 booster systems, supplying cooling and freezing of the products in the store and air conditioning (AC) of the shop area by cooling a glycol circuit supplied to the air handling unit (AHU). The design capacity of the refrigeration system must handle all the refrigeration load and the AC load during the warmest summer day, which results in overcapacity and part load operation for most of the year. In this paper, it is proposed to replace the glycol circuit to the AHU with a combination of a CO2 circuit and a cold thermal energy storage (CTES). The CTES is using water/ice as the storage medium and can be used to store cold energy during the night and supply AC during the peak hours of the day. Numerical simulations of the proposed system demonstrate peak power reductions of 13-19% in four Norwegian locations.