Experimental Study on Heat Transfer Performance of Vacuum Tube Heat Collector with Thermal Storage

This experimental study is intended to explore the heat performance of a novel vacuum tube heat collector with thermal storage. In order to enhance the heat transfer performance, we add radial metal fins to the U-tube which is used as the heat transfer channel of water. Meanwhile, in order to increase the thermal capacity of the heat collector, the heat collector model is designed to be larger than the general collector and is filled with the phase change materials (PCMs). In the U-tube, paraffin is chosen as the PCM. Then, during the experiment, to study the energy absorption and desorption characteristics of the heat collector, we chose to test during the day and night in the summer and the transition season. The experimental results show that, at night, the outlet water temperature of the vacuum tube heat collector has been enhanced by using PCM. The outlet water temperature decreases with the increase of flow rate.