An Experimental Study On The Heat Transfer Characteristics Of Latent Functional Thermal Fluid In Mini-channels

Energy has been rapidly consumed in China with the economic development.The most energy consumption fields in china are industrial,transportation and buildings.Among them,buildings consume about one-third of the total social energy.Air conditioning systems of the buildings consumes up to 50 percent of the building energy,among them,10%-20% of this energy is cost by their distribution systems.In order to reduce energy consumption of distribution system,a latent functionally thermal fluid is applied to replace the working medium in the chilled water system,which can improve heat storage density and the convective heat transfer capability of working medium.Under the same heat transfer condition,the fluid in unit volume can take away more heat with less transmission energy.However,the specific heat transfer characteristics of latent functionally thermal fluid flows in the air conditioning system is not available.To fill the gap,in this paper,a new experimental system which combines latent functionally thermal fluid and microstructure is built,and studied on the specific heat transfer characteristics of latent functionally thermal fluid.The detailed work of this paper is given as follows:Firstly,experimental study on the heat transfer performance of water with equivalent diameter of 1.6mm and 2.6mm micro pin-fin channel was carried out.The results show that under the condition of constant Reynolds number,the wall surface temperature is increased with the flow direction in the same channel,and the wall surface temperature is increased with the addiction to heating power at a certain position of channel.The average wall temperature of pin-fin #2 is higher than the average wall temperature of pin-fin #1,but the differential between them is decreased with the increase of flux.The Nusselt number of heat transfer is increased with the addiction to Reynolds number.Based on the results,the experience formula of the average Nusselt number is proposed.Secondly,the heat transfer characteristic of latent functionally thermal fluid flows was experimental studied in the micro pin-fin channel with equivalent diameter of 1.6mm.The research shows that under constant Reynolds number,the dimension wall temperature of latent functionally thermal fluid is lower compared with water.The lowest dimension wall temperature was obtained with the suspensions concentration value of 10%.For a constant Reynolds number,the local Nusselt number is increased with the flow length,and the local Nusselt number of latent functionally thermal fluid is larger than water.However,the local Nusselt number of water increased rapidly at the end of the flow,and eventually transcend the latent functionally thermal fluid.The heat transfer characteristics in micro pin-fin channel of latent functionally thermal fluid is related to the concentration of suspensions,the construction of channel and the speed of fluid.Thirdly,the heat transfer characteristic of latent functionally thermal fluid flows was experimental studied in the above two micro rectangle channel with equivalent diameters 1.5mm and 1.6mm.The research shows that under constant Reynolds number and at a certain position of channel,the lager dimension wall temperature increases with the suspensions concentration in channel #1,while decreases in the channel #2.Similar results are obtained for the corresponding Nusselt number.Based on these results,the experience formula of the average Nusselt number is proposed.The heat transfer characteristics of latent functionally thermal fluid is related to the concentration of suspensions and the construction of channel.