ENHANCEMENT OF POOL BOILING HEAT-TRANSFER IN A HORIZONTAL WATER LAYERTHROUGH SURFACE-ROUGHNESS AND SCREEN COVERAGE

An experimental investigation was carried out to study the augmentatio n of heat transfer in saturated pool boiling of a liquid water layer o n a heated horizontal stainless steel plate by roughing the surface an d/or covering it with a single layer of stainless steel screen. The re sults were presented in terms of the boiling curves. Effects of variou s parameters - the surface roughness, liquid level and size of the sta inless steel mesh on the boiling heat transfer were examined in detail . The measured data clearly indicated that a lowering of the liquid le vel from 60 to 5 mm in water depth causes heat transfer reduction. Rou ghing the surface was found to significantly enhance the heat transfer . Use a layer of metal screen to cover the heated surface was shown to substantially augment the heat transfer especially for a shallow wate r layer if the mesh size is comparable with the bubble departure diame ter. Covering the rough surface with the metal mesh, however, reduced the heat transfer.