The numerical investigation of the finned double-pipe phase change material heat storage system equipped with internal vortex generator

Abstract

Energy storage is among the factors that could reduce the use of fossil fuels. Having a large heat storage capacity, phase change materials found their wide applications in energy storage applications. The present study investigates the effect of using phase change materials on the performance of a double pipe heat storage system. The three-dimensional simulation was developed to model the transient flow and heat transfer via the finite volume method. To enhance the heat transfer, fins with the varying cross-sectional area are employed over the surface of the inner tube. Furthermore, to enhance the water side heat transfer, the vortex generator is employed there. The sensitivity analysis was performed to unveil the effect of inlet hot water temperature on the change and discharge processes. The results show that the fins inside the phase change material reduce the melting time up to 100 min and increase the outlet hot water temperature. Also, using the vortex generator in the water path had the reverse effect on the charging process and increases the charging time. For hot water temperature of 75 °C, the temperature of phase change material archives to its maximum value after 189 min. In the case of 70 °C hot water temperature, the phase change process begins 41 min later than in the case of temperature 75 °C and reaches its maximum temperature within 229 min.