Experimental Study On The Effect Of Condensation Heat Transfer Characteristics Of R245fa In Horizontal Tube With Conical Mesh Insert

The condensation heat transfer in the tube is mainly affected by the gas-liquid phase distribution and the working fluid flow field,which is embodied in the mass steam quality x of the gas-liquid mixture and the working fluid mass flow rate G.In this paper,two kinds of conical meshes with different surface lyophilic properties were inserted into the copper tube with diameter of 14.86 mm.The conical mesh divides the copper pipe cross-section into an annular region(the area between the conical wire mesh and the tube wall)And the core region(the inner region of the conical wire mesh),the effect of the conical wire mesh on the macro-flow pattern modulation and the condensing heat transfer enhancement ability was studied by changing the vapor-liquid phase distribution and the flow field control to strengthen the R245 fa condensation heat transfer.The role and mechanism of lyophilic properties of the surface of the wire mesh played.The conical wire mesh can improve the mass steam quality near the wall surface by capturing the droplets in the two-phase flow.The direction and size of the fluid velocity are changed to make the flow field and the temperature field more synergistic,which can strengthen the condensation heat transfer.In the two kinds of wire meshes,he surface lyophilicity of the conical mesh with nano-micron composite structure was constructed on the surface was better,the droplet spreading driving pressure difference was larger,the droplet capture efficiency was higher;Micropore suction effect is stronger,thus strengthening the tube condensation heat transfer effect is better,the maximum strengthening of 2.46 times.The micropore of the wire mesh separates the saturated gas in the annular region and the pipe wall by the surface tension,and continuously collects the condensate in the annulus area to the core area,and the mass void fraction x of the annulus area increases significantly improve the annular region mass flow rate G While reducing the flow cross-sectional area,enhanced heat transfer enhancement effect.The conical wire mesh can effectively improve the macro performance of the condenser through the microstructure and help to reduce the metal consumption of the heat exchanger,reduce the investment cost,promote the utilization of low grade waste heat and new energy development.