Experimental Study On Boiling Heat Transfer Of Different Structural Parameter Copper Foams Under Different Pressures

A large number of experiments and studies have shown that the copper foam can enhance the heat transfer performance of the heat pipe,but the heat transfer performance of heat pipe is influenced by many factors,the explanation of the copper foam for strengthening heat transfer is macroscopic.This paper aims to study the boiling heat transfer of the different structure parameters of copper foam under different pressures.And the boiling heat transfer mechanism of copper foam is explained by the bubble,which can provide guidance for the application of foam copper in heat exchangersFirstly,we have designed and successfully built a experimental bench which can test the boiling heat transfer performance of different kinds of heating surfaces.And then we process the smooth surface,the different pore density of the copper foams,the different thickness of the copper foams and the gradient pore copper foams.And we also characterized the heat surface by a magnifier in this paper.On the test,this paper first explores the boiling heat transfer test of the smooth surface and a kind of copper foam surface.The test results show that the superheat of copper foam is about 3 degrees Celsius lower than the smooth surface at ONB.And the highest CHF of the porous surface was 136.7W/cm2,which is 20% higher than that of the plain surface.Secondly,the the boiling heat transfer performance of the different structure parameters copper foam was studied in this paper.The data indicated:(1)With the increase of foam metal PPI,the heat transfer capacity of foam copper increases firstly and then decrease.(2)the heat transfer capacity of copper foam decreased firstly and then increased with the increase of the thickness of the metal foam.(3)The heat transfer capacity of high PPI copper foam is better than the smooth surface significantly under low heat flux range,but the advantage is weakening under high heat flux range.Compared with the low heat flow region,the boiling heat transfer performance of the low PPI foam copper is better in the high heat flux region,but the whole boiling heat transfer performance is only slightly better than that of the smooth surface.However,the gradient porous copper foam has the advantages of high porous density and low porous density copper foam,the boiling heat transfer performance is significantly better than the smooth surface under the whole heat flux range.Finaly,this paper also study on boiling heat transfer of different structure parameters copper foams under different pressures.The experimental results show:(1)The boiling heat transfer performance of both smooth surface and low PPI copper foam improves with the increase of pressure,but the boiling heat transfer performance of high PPI foam copper decreases with the increase of pressure under high heat flux region.(2)The boiling heat transfer coefficient curves of copper foam are similar to those of smooth surface under different pressures.(3)Compared with single PPI copper foam,the boiling heat transfer performance of gradient pore copper foam is stable under different pressure.