On the performance of a latent heat thermal storage unit integrated with a helically coiled copper tube and organic phase change materials: A lab-scale experimental study

In this study, the performance of a latent heat thermal storage (LHTS) unit integrated with a helically coiled copper tube and organic phase change materials is investigated using a lab-scale experimental setup. The effects of various operating conditions such as the coil thickness, testing fluid temperature/flow rate, PCM type, turbulator, and stirrer rotational speed on phase change behavior are investigated. The evaluation is based on PCM temperature variations, total heat transfer coefficient, and thermal effectiveness. The effects of testing fluid temperature, PCM type, turbulator, and stirring speed on phase change behavior are found to be more pronounced compared to those of the coil thickness and the fluid volume flow rate. Considering the melting process, it is found that the average temperature of the PCM in the LHTS unit with a turbulator is higher than that of the case without turbulator by nearly 10 °C which indicates an improvement in the heat transfer between water-PCM. The average PCM temperature is found to increase by 2 °C and 3.5 °C when a stirrer with a rotational speed of 200 and 400 rpm is employed, respectively. The total heat transfer coefficient for the LHTS unit at a stirring speed of 400 rpm (200 rpm) shows a significant increase of 39.6% (27%) compared to the scenario without a stirrer.