Study on the performance enhancement of ice storage and melting processes in an ice-on-coil thermal energy storage system

Air conditioners equipped with an ice storage system store a large amount of latent heat during the off-peak period at night, and use the stored cold energy for the air conditioner during the peak period of the day, thereby greatly reducing peak power consumption. In this study, an experimental analysis was conducted to evaluate the cold storage and cooling characteristics of an ice-on-coil storage system. Firstly, the influence of the inlet brine temperature, flowrate, and concentration on the discharge rate was studied. It was observed that all parameters were directly proportional to the discharge rate, and the effect of brine inlet temperature was more pronounced. Secondly, the alumina nanofluid as a phase change material was employed in the system for enhancing the thermal performance. The experimental results showed that using nanofluid shortened the freezing time, while it had a negative impact on the thermal behavior during the ice melting. Thirdly, the ice storage coils with spiral fins were used. It was concluded that the employment of finned coils reduced the melting time by 24.0 %, increased the average discharge rate by 74.4 %, and raised the cumulative discharge capacity by 63.5 % compared with original bare coil design.