9th International IFS and Contemporary Mathematics and Engineering

Abstract

PCM-based thermal energy storage systems provide an effective means of capturing, storing, and releasing thermal energy. Their high energy storage density, temperature control capabilities, and contribution to sustainable energy practices make them a promising solution for optimizing energy utilization and reducing environmental impact. However, their low thermal conductivity values significantly limit their usability. Integration of PCMs with graphite matrix can significantly improve thermal conductivity, thereby enhancing energy storage efficiency. The main focus here is to ensure the effective maintenance of thermal energy and minimize energy losses by contributing to the development of more sustainable energy storage solutions. In this work, a numerical study has been conducted to predict the effect of environmental conditions on the thermal energy storage performance of graphite matrix saturated with PCM (paraffin) for solar thermal energy and waste heat recovery, including different convection heat transfer coefficient values of 0, 5, 10, and 50 W/m2K, which refer to adiabatic, natural convection/still air, forced convection with fans (air conditioning), and windy weather, respectively. The effect of the convection heat transfer coefficient is evaluated for different bulk density values of 100 kg/m3 and 143 kg/m3. Results indicated that uniform melting behavior was observed in the PCM/graphite matrix composite due to the high porosity of graphite, which allowed a dominant conduction heat transfer mechanism, and energy storage rates climbed with the increase in bulk density. Higher heat transfer coefficient values cause a higher total melting time and lower thermal energy storage rates. The effect of the convection heat transfer coefficient on total melting time is appreciable for 50 W/m2K compared to lower h values for each bulk density. The effect of the convection heat transfer coefficient is lower for a higher bulk density of 143 kg/m3. On the other hand, the effect of bulk density on the energy storage rate is maximum 9% for lower convection heat transfer coefficients (<50 W/m2K), while the impact level of bulk density increases to 15% at 50 W/m2K.