Natural convection in water-saturated copper foam is measured for 2.5 × 10-4 < Da < 1.2 × 10-5, 10 < Ram < 210, and 7.5 × 105 < Raf < 2.5 × 108. Experiments are reported for foam with 92% porosity and 10 and 20 pores per inch. The primary finding is that the Nusselt numbers do not follow the published heat transfer correlations with Rayleigh number for a packed bed of spheres and are 27-42% less than that predicted by these correlations at the maximum Rayleigh numbers encountered for Da ∼ 10-5. A single heat transfer correlation of Nusselt number is obtained in terms of Rayleigh and a modified Prandtl number equal to Prm Da- 1 / 2 Cf - 1. In comparison to natural convection in a water layer, enhancement of heat transfer is primarily via conduction. Enhancement of the advective component of heat transfer is obtained only for Raf ∼ 108 and 1.2 × 10-5 ≤ Da ≤ 2.4 × 10-5.
|Original language||English (US)|
|Number of pages||9|
|Journal||International Journal of Heat and Mass Transfer|
|State||Published - Jul 15 2008|
- Metal foam
- Natural convection
- Porous media