Experimental and Theoretical Analysis for the Performance of Evacuated Tube Collector Integrated with Helical Finned Heat Pipes using PCM Energy Storage

Evacuated Tube Solar Collector is a promising type of solar heaters. As an energy storage media, paraffin wax found to has a low thermal conductivity in both charging and discharging processes. In this paper, an Evacuated Tube Solar Collector with a helically finned heat pipe experimentally studied. Two collectors used during the tests. The first was the control system, including the conventional fins type. While the second one was the helical fins type. The experiments carried out considering flow rates of 0.165, 0.335, 0.5, and 0.665 L/min. Tap water was used as a heat transfer fluid. The results showed that the helical fins archive better temperature homogeneity in Paraffin along the tube axis than the conventional fins. Under the same flow rate, the maximum temperature difference was found to be 4 degrees C and 12.25 degrees C for the helical and the conventional fins systems, respectively. The helical fins found to achieve a daily efficiency enhancement over the conventional one by 15% and 13.6% for the flow rates of 0.5 and 0.665 L/min, respectively. Moreover, the solid to liquid phase change started in the helical fin system after the conventional one by 30-60 min. (C) 2020 Elsevier Ltd. All rights reserved.