ENHANCEMENT OF HEAT-TRANSFER BY INSERTING A METAL-MATRIX INTO A PHASE-CHANGE MATERIAL

Increase in the heat transfer rate during melting and freezing of a ph ase change material (PCM) with a low thermal conductivity is demonstra ted by inserting a high-porosity metal matrix into the PCM. A vertical annulus space (r(i) less than or equal to r less than or equal to r(0 ), 0 less than or equal to z less than or equal to h), homogeneously f illed with water and an aluminum matrix, is selected for this study. T he Navier-Stokes equations are modified to account for Darcy's effect. For both the melting and freezing cases, the density inversion phenom enon of wafer is considered. The irregularity and time-varying nature of the solid and the liquid regions are accounted for by a geometric c oordinate transformation. The numerical results are presented in the f orm of solid-liquid interface movements, isotherms, streamlines, and h eat transfer rates for some representative cases. The heat transfer ra tes for enhanced cases show an order-of-magnitude increase over the ba se case, there no metal matrix is inserted.