ANALYSIS OF NEAR WALL HEAT TRANSFER IN POROUS MEDIA USING A TWO EQUATION MODEL
Forced convection heat transfer from an isothermal surface submerged in a saturated porous medium is studied using a two energy equation model. Systems having the thermophysical properties of water and glass beads, water and steel shot, and air and glass beads are examined. The computed heat transfer is shown to depend very strongly on the model of the near wall porosity used in the calculations and the assumed contact conductance between the solid phase and the surface. The predicted heat transfer decreases with increased contact conductance. Results are also dependent on particle size since the near wall velocity depends on particle size. For smaller particles the heat transfer is higher for the same value of the contact conductance. The solution is not strongly dependent on the fluid to solid convective heat transfer coefficient. Even though the model predicts temperature differences between the solid and fluid phases that are small, these differences are shown to have a significant effect on the resulting heat transfer. Predicted results for water and glass beads are in reasonable agreement with available experimental results and the volume averaged theory. However, results for the other two systems are significantly below predictions made using the volume averaged theory.