Experimental investigation of heat transfer of flowing liquid film with inserted metal foam layer subjected to air jet impingement

Abstract

In this paper, coupling the air jet impingement and the copper metal foam above flowing liquid film were employed to enhance the heat transfer. The thickness of flowing liquid film can be controlled owing to the application of the metal foam above the film, and its solid matrix extends the air-liquid-solid interface of heating surface. The evaporated water can be supplied by the capillary force in the porous layer. The experiments were conducted to investigate the performances of the flowing liquid film with inserted porous layer subjected to impinging jet air. The air jet velocity, the flow rate and thicknesses of the liquid film as well as the porosity of metal foam influence the surface temperature of heated wall and the corresponding local heat transfer coefficient greatly. The change ratios of heat transfer coefficient due to the above factors were presented. More cooling can be obtained on the heated wall in the flowing liquid film with inserted porous layer subjected to impinging jet air while the higher liquid film velocity and air jet velocity, the thinner liquid film and the lower porosity of metal foam occur.