Experimental and theoretical analysis of an aluminum foam enhanced phase change thermal storage unit

This paper investigates heat transfer enhancement of a shell-and-tube latent heat thermal storage unit, using water as the phase change material, by addition of open-cell aluminum foam. The experimental results indicated that the foam significantly increased the heat transfer during both solidification and melting, as characterized by the overall heat transfer coefficient. The relative enhancement was greater for melting than solidification due to the lower thermal conductivity of liquid water relative to ice. The value obtained in this work for melting is significantly lower than predictions from existing effective thermal conductivity models for foam composites, and as is shown, the impact of this discrepancy on the overall thermal performance of the thermal storage unit is significant. This finding is further demonstrated by numerical investigation of phase change in a representative composite material containing a foam-like structure modeled on the well-known Kelvin cell.