The efficiency of round channels fitted with porous, highly heat-conducting insert in a laminar fluid coolant flow at boundary conditions of the third kind

摘要

An important problem of the development of thermal power engineering today is the development of compact, highly efficient heat exchangers that are made of porous materials with high heat conductivity. Along with obvious advantage - high efficiency of heat transfer due to high heat conductivity of porous material, there is also a disadvantage - high hydraulic resistance of porous structures. The purpose of this work was to discover the area of parameters of porous heat exchangers, where gain in heat transfer would exceed losses in hydraulics. Computation of comparative efficiency was carried out for porous materials made from metal-felt with a laminar flow of an incompressible fluid - water and boundary condition of the third kind. Smooth-wall pipe was taken as a standard surface for comparison.rnThe accounts showed that the increase in the efficiency of porous channels occurs with decrease in the diameter of the channel, in the difference of temperatures of the environment and coolant at the beginning of the pipe, decrease in the Biot number, increase in the porosity, increase in the Reynolds numbers in the compared channel with a smooth wall and decrease in the relative length of compared channels with a smooth wall.