Numerical investigation of natural convection enhancement in latent heat energy storage units with punched-fin and slit-fin

Abstract We study the melting process of phase change materials (PCM) inside a shell-and-tube heat exchanger with punched-fin and slit-fin numerically based on the enthalpy-porosity model in the present paper. The phase change material used is paraffin wax. A comparison of the liquid fraction, the total melting time, and the average temperature was performed to assess the improvement of the melting processes for six fin designs. The numerical results reveal that the usage of punched-fins and slit-fins can improve the melting rate because of the decrease of the blockage effect. For slit-fin cases, the reduction percentage in the total melting time has nearly the same value at different Stephan numbers, and an almost 14.0% improvement is observed compared to the straight fin case, while for punched-fin cases, the reduction percentage varies for different Stephan numbers, and the maximum value of the reduction percentage is 10.1%.