The Conjugated Heat Transfer Characteristics In The Channel Of Rectangular Plate-fin Heat Exchanger

With rapid developing of economic, a production mode which has higher efficiency, more energy saving in heat exchange link of production department is more and more appealed. As a compact, efficient recuperative heat exchanger, plate-fin heat exchanger has been massively applied in actual production process. In recent years, lots of plate-fin heat exchanger of various materials and new type fins are using in practical application. Plate-fin heat exchangers are more used in cooling elements of electrical equipments. There are two boundary conditions in the numerical study of plat-fin heat exchanger, one is uniform wall temperature boundary, and the other is uniform wall heat flux boundary. But in actual heat exchangers, thermal boundary is not same as these boundaries. It is regarded as mixed thermal boundary because heat needs to pass zones of plates and fins, and temperature and heat flux of walls are not uniform distributed. If numerical method are used to capture the heat transfer characteristics of the mixed thermal boundary condition, conjugated heat transfer should be considered.In this paper the numerical study of heat transfer characteristics of the rectangular plate-fin heat exchanger channel under mixed thermal boundary are performed, its characteristics are compared to the corresponding results under uniform wall temperature boundary and uniform wall heat flux boundary. The studies include developing the heat transfer model of the rectangular plate-fin heat exchanger channel, the discretization of the governing equations, the code making, the solving of the discretization equations, and then obtaining its heat transfer characteristics.The results show that under mixed thermal boundary condition axial mean Nusselt is3%～4%larger than local Nusslet under uniform wall temperature condition and is26%～27%smaller than local Nusslet under uniform wall heat flux condition.