抄録
The heat transfer from a high-temperature solid surface to a porous plate containing water and separated by a narrow gap and the resulting water evaporation from the plate are investigated experimentally. The pressure field established in the clearance due to the induced vapor flow enables the high-temperature solid to hover without contacting the plate. This hovering phenomenon is expected to be applied to high-temperature material processes such as plate glass formation. The surface temperature of the solid, the magnitude of the clearance and the temperature of the water supplied to the plate are varied widely as the experimental parameters. The heat transfer and evaporation rates increase with the increase in the solid surface temperature up to 1273 K and with the decrease in the clearance from 1.0 mm to 0.25 mm, while the temperature near the upper surface in the plate remains close to the saturation temperature over the parameter ranges implying that the water is sufficiently distributed over the entire thickness of the plate. The heat transferred from the high-temperature solid is mainly consumed as latent and sensible heats of the vapor and sensible heat of liquid taken up for evaporation from the lower surface. After a significant delay following the sudden cessation of water supply, the plate temperature begins to increase rapidly due to the increased dry area. This delay is shorter than the evaporation period estimated by assuming steady-state evaporation up to the critical moisture content under mild heating conditions.
