Heat transfer from a surface into a confined gap over a saturated porous plate

Experiments were performed to study the heat transfer from a 35 mm wide heated foil into a confined gap over a saturated porous plate, with a nominal pore size of 50 μm, using distilled water as the working fluid. The surface temperature distribution on the central portion of the heated foil was measured using a high speed thermal imaging camera. Experiments were performed for gap sizes of 0-1000 μm and heat fluxes of 11.7-58.3 kW/m2. The gap size was found to have a significant effect on the boiling dynamics beneath the heated surface, with the highest heat flux achieved for a gap size of 600 μm, similar to previous results for a heated surface with a width of 10 mm. The results here indicate that the boiling dynamics within the confined gap were independent of the heater width. The heat transfer performance, however, was not with earlier dry-out for the wider heated surface considered here.