Numerical and Experimental Investigation on Heat Transfer Performance of a Solar Single Storage Tank

Abstract

The single-tank latent heat thermal energy storage (LHTES) of solar energy mainly consists of two modules: the first one is the phase change material (PCM) module heated by solar energy; the second is a module of heat transfer between melted PCM and the user’s low-temperature water. This paper mainly focuses on the former one. To investigate the heat transfer performance of the paraffin-based solar single storage tank and find a more suitable experimental configuration, as basic research work, we established a single-tank thermal storage platform and then conducted a numerical simulation on the heat transfer process with Fluent. The result of numerical simulation shows that the test situation was basically reflected and the data agreed well with the experiment results. The numerical simulation analysis is accurate and the method is reliable. To obtain the heat transfer performance of paraffin in a single tank and strengthen heat transfer, the aspect ratio, the melting temperature of paraffin, and the heating power of the electric heater were analyzed based on simulation. The results show that the heat transfer gets more uniform when the aspect ratio is lower. This results in an increase in the liquid fraction of 61.83% to 76.47% one hour after heating when the aspect ratio of the tank reduced from 2.8 to 1.1. The higher the melting temperature of paraffin, the longer it takes for PCM to reach a stable state. And the curvature of liquid heating is greater than that of solid heating at the bottom layer. Under the constant total work, the heating power has little effect on the heat transfer performance of the paraffin. This study will provide some reference value for the optimization design of single-tank LHTES systems in the future.