Numerical study on heat transfer enhancement of shell-and-tube thermal energy storage unit using metal foams with non-uniform porosity

Abstract

ABSTRACT Using metal foams mitigates the low thermal conductivity of phase change materials (PCMs) in latent heat thermal energy storage (LHTES). However, the heat transfer within PCMs is not uniform due to natural convection. In the present study, the effect of the porosity distribution on the heat transfer performance of shell-and-tube thermal energy storage (TES) was analyzed. The results demonstrated that the melting rate and average heat transfer rate both were improved as the porosity gradient increased along positive y-direction. Compared with the uniform porosity (ε = 0.94), the average heat transfer rate was enhanced by 21.6% for ε = 0.94 + 0.267y during the melting process. For the porosity gradient increasing along outer radius direction, the heat transfer rate near the heating wall was improved, while the phase change process of PCM near the outer wall slowed down. The maximum of average heat transfer rate existed for ε = 0.88 + 0.6r.