Thermo-economic study of cold thermal energy storage with various storage scenarios in a supermarket located in tropical climates

In this study, ten different cold thermal energy storage (CTES) scenarios were investigated using thermodynamic and economic analyses and compared to the direct cooling system in a supermarket. The energy analysis of CTES system was carried out to predict its behavior during the charging and discharging phases. The coefficient of performance (COP) of the chiller was determined for all CTES designs on an hourly basis, considering the ambient temperature profiles of the local climate. A daily energy analysis, and an annual savings analysis were conducted for the whole system. The daily electricity tariffs of CTES scenarios decreased compared to the direct cooling system as storage capacity increased, leading to higher annual profits and a reduction in the payback period. It was found that eliminating chiller operation during peak hours in all CTES designs increases system capacity and CTES volume, which in turn raises net energy consumption and initial capital costs. However, this approach results in significant annual savings, despite a rise in service costs, and remains more beneficial compared to running the chiller 24 h a day. Overall, the leveling storage off-peak mode proved to be the optimal CTES design, offering substantial annual savings and the shortest payback period of six years, without requiring significant modifications to the existing chiller plant.