ESTIMATION OF THE LOCAL HEAT TRANSFER COEFFICIENT IN FORCED CONVECTION OF MOIST AIR IN PRESENCE OF WATER VAPOUR SURFACE CONDENSATION

An estimation technique which enables to determine the local heat transfer coefficient, has been here successfully applied to the forced convection of a moist air stream in presence of water vapour surface condensation. The surface temperature distribution on a locally cooled metallic plate, fitted on a wind-tunnel’s wall where a humid air stream flows, has been acquired by an infrared camera. The thermal maps have been used as the input data of the estimation procedure, based on the solution of the Inverse Heat Conduction Problem in the wall. The procedure, which develops iteratively, is based on the forced matching between the numerical solution of the corresponding direct problem and the experimentally acquired data. This approach enables to find a boundary condition for the problem, that is a heat transfer coefficient distribution, coherent with the experimental temperature data. This procedure, well established in single-phase convection problems, has proved to be robust and to give reliable results also in the more critical condition represented by the convection problems which occur in presence of surface vapour condensation.