Experimental and numerical study of the melting process of phase change materials with novel finned heat storage tank under non-steady state conditions

The efficient utilization of sustainable energy is one of the important studies in the world. Latent heat thermal energy storage (LHTES) technology can effectively utilize sustainable energy. However, sustainable energy such as solar energy has the challenge of supply-demand imbalance. To address this challenge, this paper performs a study on the effect of unsteady inlet temperature on the thermal storage characteristics of LHTES. The study uses a combination of experimental and simulation approaches. Four different inlet temperature modes are selected, respectively steady state, sinusoidal unsteady state, cosine unsteady state, and segmented. The segmented temperature mode has two different cases. The results of the study show that the sinusoidal unsteady inlet temperature has the advantage of energy storage. The melting time of the sinusoidal unsteady state is optimized by 5.3 % compared to the steady state inlet temperature and by 10.0 % compared to the cosine unsteady state. Segmented inlet temperature modes do not have a significant optimization effect. Also, the sinusoidal unsteady inlet temperature has the largest average Nusselt number, with a number of 8.2, and the convective heat transfer inside it is more intensive. The results of the study can provide guidance for the efficient utilization of sustainable energy and can give a reference value for the enhancement of phase change heat storage technology.