Optimization of shell fin-tube heat exchanger for phase change thermal energy storage

Abstract

The study of waste heat recovery of Phase Change Materials in Thermal Energy Storage unit have been popular over recent years. With the utilization of fins, studies showed that it can enhance the heat transfer rate in the system. In this study, an experimental test is conducted to investigate the optimization of shell-fin tube heat exchanger for phase change thermal storage. A full experimental set-up and experimental procedure is designed and implemented. The shell-fin tube heat exchanger contained fins of four different configurations and is tested in the horizontal and vertical orientation. It is subjected to testing at three different volumetric flowrates of 0.25 L/min. 0.40 L/min and 0.55 L/min with input temperature of the Heat Transfer Fluid kept constant at 70°C. In addition, in the vertical orientation, input temperature was varied between (50-70) °C while keeping the volumetric flowrate constant at 0.40 L/min. From the experimental results of the horizontal and vertical orientation, following comparisons were made 1) melting behavior of PCM at four different fin configurations, 2) effectiveness of fins at the three different flowrates and 3) heat transfer rate at each fins. It was found that in the horizontal orientation, Fin 3 should be utilized at 0.25 L/min which yielded a heat transfer rate of 100 mW. Whereas in the vertical orientation, Fin 1 and Fin 3 should be utilized at 0.25 L/min which yielded a heat transfer rate of 125 mW for both fins. In addition, at the vertical orientation, a comparison was made between the input temperatures and found that as the input temperature increases, the time taken for phase change process decreases with Fin 1 showing optimal heat transfer rate of 250 mW at 60°C. In all cases, the role of the flow rates and input temperature plays a crucial role in determining the effectiveness of a shell-fin tube heat exchanger. The various effects and phenomena surrounding the fin effectiveness is also discussed in the paper. Future recommendations is discussed at the end of the study, to help further improve the study in the future and future areas of study is also suggested.