The effect of aspect ratios and inclination angles on the thermal energy storage of phase change materials in partially filled metal foam

Abstract

This paper conducted a numerical study on the thermal energy storage (TES) of partially filled metal foam composite phase change materials (PCM) in rectangular cavity devices. The melting mechanisms under different aspect ratios (AR) and inclination angle models were analyzed, and a predictive formula for the dimensionless TES rate density z' was established. The results indicate that the TES performance of PCM improves with the increase of AR. When AR = 2, the enhancement efficiency reaches 22.6 %, exhibiting the optimal improvement effect. When AR is greater than 8, heat conduction dominates the entire melting process. The natural convection effect is the best in the 60° inclination angle model. When AR = 1, the energy storage performance at θ = 60° is 5 % higher than that at θ = 90°, but for other ARs, θ = 60° leads to a decrease in performance. This is because the change in inclination angle triggers the Rayleigh - Bénard convection phenomenon, generating counter - rotating vortices that inhibit the energy storage efficiency, and as AR increases, the inhibition becomes more significant. The established predictive formula takes both AR and inclination angle into account, which is more comprehensive.