Experimental Study On Heat Transfer Resistance And Equivalent Thermal Conductivity Of Porous Medium Metal Foam

With the development of mankind and the progress of science and technology,the demand for energy is increasing,and the problem of energy shortage has been paid more and more attention.Improve energy efficiency can be green and economical to reduce energy consumption,is the first choice for energy conservation.Porous media metal foam as a new type of material has been widely concerned in the aerospace,electronics and other fields.It has the characteristics of enhanced heat transfer due to the porosity and metal rigidity.In recent years,the study of heat transfer in porous media has become a hotspot,and the description of heat transfer model has become more and more mature.However,in the energy equation description,the choice of thermal conductivity for porous media is still controversial.In this paper,the equivalent thermal conductivity is proposed for the definition of the thermal conductivity in the two energy models,and the equivalent thermal conductivity is calculated by using the foam copper as an example.In this paper,the heat transfer thermal resistance measurement device of porous metal foam was established,and the total thermal resistance,skeleton thermal resistance and surface contact thermal resistance were measured.The influence of different factors such as thickness,structural parameters,heating power and compression force on the experiment was analyzed.The experimental results show that the total thermal resistance decreases with the increase of the compression force,and the maximum reduction is up to 50%.The skeleton thermal resistance was obtained by the deduction of the data of different thickness specimens.When the porosity is similar,the larger the pore density(PPI)is,the smaller the thermal resistance is.If the porosity density(PPI)is the same,the thermal resistance increases with increasing porosity.The surface contact thermal resistance has a great influence on the heat transfer and the surface contact thermal resistance value of the specimen was calculated.An equivalent thermal conductivity which is more consistent with the heat transfer mechanism of porous media is proposed.Based on the principle of thermal resistance consistency,the effective thermal conductivity area of cube filament model and tetrakaidecahedron model is calculated according to the definition of equivalent thermal conductivity.The equivalent thermal conductivity of the model is obtained by combining the experimental data of skeleton thermal resistance with the model parameters.