CFD approach for the enhancement of thermal energy storage in phase change material charged heat exchanger

Abstract

The objective of this research work is to evaluate thermal performance capabilities of a heat exchanger having multiple circular tubes incorporated with three and six fins and a phase change material (PCM) charged in the shell region of the heat exchanger. Present study has been performed using two-dimensional computational fluid dynamics (CFD) model. To study the phase transition of the solid PCM and optimize the design of the cylindrical tubes based on the operating circumstances, a two-dimensional CFD simulation with a physical enthalpy-porosity approach is utilized. The effects of incorporating a number of fins on the tubes on heat transmission have been investigated in terms of liquid percentage and PCM mean temperature at two applied temperatures of 50°C and 60°C. While using a fixed temperature of 50°C, it was discovered that cylindrical tubes with three and six fins improved heat transmission in the PCM and reduced melting time from 780 s for a design having no fin to 650 s for a design having three fins and 580 s for a design having six fins. Results shows, when PCM melting begins, conduction is predominant and around the tubes, the melt zones are similar. However, convection heat transmission in PCM begins after 100 s in a configuration without fins, 80 s in a configuration with three fins, and 60 s in a configuration with six fins at 50oC. After 60 s, 24.6% of PCM is transformed into liquid in a setup without fins, 35% in a configuration with three fins, and 43.3% in a configuration with six fins. After 180 s, liquid percentage is 57.4% in the design without fins, 71.3% with 3 fins, and 79.6% with 6 fins. Results shows that adding 6 fins on tubes perimeter increases heat transmission. Results have been validated with literature results.