Experimental Study On Enhanced Convective Heat Transfer In Tube With Metal Foam

With the rapid development of society,the excessive exploitation of energy and the increasingly serious environmental problems,we have to solve the problem of energy shortage,improve the efficiency of energy utilization.And heat energy as the main form of the energy utilization,mainly through the heat exchanger of energy conversion,metal foam has them has larger specific surface area,large porosity special properties,such as its structure at the surface of heat transfer enhancement exactly the passive technology extension method,and because of its unique porous structure can effectively broken laminar bottom,increase the degree of turbulence and improved thermal effect,and has a metal frame,so the heat conduction ability is higher,so makes it has very good heat transfer performance on reducing heat exchanger volume,improve heat exchanger performance has a great help.However,according to the literature,when the Reynolds number is the same,the Nusselt number of heat exchanger with metal foam is increased obviously,but the pressure drop is also increased.Therefore,this paper compared two kinds of foam metal heat exchange tubes under the condition of pump work,and analyzed the pressure drop and Nusselt number of each heat exchange tube by controlling the different variables of the two kinds of foam metal heat exchange tubes.In this paper,inspired by grooves for the ring metal foam filling of convective heat exchange tube research,using 3 D printing technology,printing spiral flow channel,recycled foam metal heat exchange tube processed grooves,Yin line analogy foam metal groove,Yin diameter as pipe diameter,diameter Yin and Yang of the difference of the diameter as the thickness of the foam metal filler,Firstly,the performance of ring-type foam-filled metal heat exchanger tube is studied.Secondly,according to the existing literature know the location of the metal foam filler has significant effect to exchange heat and flow characteristics,design the spiral belt type metal foam filler again so,ring type filling by calculation of heat exchange tube of metal foam filling quantity,determines the spiral belt type foam metal filling quantity,control of the two kinds of filling amount of foam metal fill the same way,At the same time,the Reynolds number of the two heat transfer tubes is controlled.Finally,two kinds of materials with porosity and void density were selected to compare the two filling methods.Finally,the flow,heat transfer and PEC of the two kinds of heat exchange tubes are evaluated comprehensively.According to the experimental results,when the spiral Angle is 120°,the spiral belt type metal foam heat exchange tube has the highest comprehensive evaluation index,and under the same conditions,the spiral belt type metal foam heat exchange tube has better comprehensive performance than the spiral belt type metal foam heat exchange tube.The analysis of the twist Angle of spiral band foam metal shows that the pressure drop gradually decreases as the twist Angle increases from 0° to 280°,but when the twist Angle increases from 280° to 360°,the pressure drop suddenly increases,and the comprehensive evaluation index of the spiral band heat exchange tube of 280° is also the highest,but the change of Nussel number is not obvious.