Study On Heat Transfer In Plate Channel Enhanced By Metal-foam

Metal foam is a kind of multi-functional new material which has large surface area in finite volume,low density and high strength.The application of metal foam materials in the field of enhanced heat transfer is a branch of many applications.In this paper,the forced convection flow and heat transfer characteristics in plate channel partially filled with metal foam have been studied,there are two kinds of filling geometries: the asymmetrical channel with metal-foam sintered on the single heated wall and the symmetrical channel in which both walls of the channel have been heated and sintered with metal-foam.The Brinkman-extended Darcy momentum model and non-equilibrium heat transfer model were employed for metal-foam region and combined with the momentum and energy conservation equations for foam free region to set up the differential equations for parallel-plate channels partially filled with metallic foams.The equations coupling with the corresponding boundary conditions have been solved analytically to derive the analytical solutions and predict fluid velocity distributions and temperature distributions of two kinds of plate channels.The results show that the effects of the key parameters,such as pore density,porosity,thermal conductivity of metal foam and the height of metal-foam region,on the flow and heat transfer performance were discussed.Comparing to parallel-plate channel fully filled with metallic foams,in which heat transfer performance can be enhanced by high pore density and low porosity,the effect of pore density and porosity on heat transfer in the partially filled plate channel depends on the height of the metal foam region.Because there is an implicit parameter: the metal foam region fluid flow ratio,which is determined by the aforementioned key parameters and means the percentage of fluid flowing through metal-foam filled region.The overall heat transfer performance depends on the balance of enhanced heat transfer and fluid distribution,then calculation for optimization of the heat transfer performance of the partially filled plate channel becomes more complicate.Finally,the analytical results of two kinds of channels are used to analyze the overall heat transfer performance and of plate heat exchangers composed of these two kinds of channels and optimize them.