Temperature control performance and cooling releasing characteristics of PCM in large space: case study of cold storage

In order to achieve carbon neutrality and carbon peaking, phase change material (PCM) is widely used in small space scenarios such as refrigerated trucks and cold storage containers due to their high energy storage density and controllability. But there is few research on the applications of PCM in large spaces. With the rapid growth of the cold storage scale, PCM-based cold energy storage system (CESS) can effectively utilize the peak and valley power resources and reduce the excessive dependence on the power grid. In this study, a PCM-based CESS was designed for a large-scale cold storage. Based on a two-dimensional simplified model of cold storage, the optimal and economical utilization number of the PCM plates was determined through the numerical simulation to meet the requirements of the cold storage temperature and temperature control time. Meanwhile, the air temperature field, the flow field and the dynamic cooling releasing characteristics of the PCM plates in the process of cooling releasing were analyzed further. According to the results, it can be found out that with the PCM-based CESS, the time for the temperature of the cold storage maintaining below required value was prolonged when the refrigeration system was turned off. The temperature field in the cold storage appeared to be stratified and the flow filed was turbulent around the PCM plates and gaps during the cooling releasing. In addition, the melting time and the melting degree of the PCM plates were not uniform at different positions with a large internal temperature difference.