Study On Two-phase Flow Pattern And Flow Resistance In Horizontal Tube With Mesh Wick

In order to explore the influence of inserting mesh wick into horizontal tube on the thermal performance of the tube,in this paper,air and water as the medium,the flow pattern and flow resistance in horizontal tube of common smooth horizontal tube and horizontal tube with different types of mesh wick are studied and compared.In this paper,an experimental platform for flow pattern observation and pressure drop measurement in horizontal tube is designed and built,and conducts experimental research on the flow process of deionized water and air two-phase fluid in the horizontal tube.There are three typical flow patterns,smooth stratified flow,wavy stratified flow and annular flow,as deionized water conversion velocity Jl = 0.017-0.88 m / s and air conversion velocity Js = 0.3-15 m / s in the tube.The flow pattern zoning map of the smooth tube is drawn with the converted gas flow velocity Js as the abscissa and the converted liquid flow velocity Jl as the ordinate.The results are basically consistent with that of the Mandhane flow pattern zoning map.In this paper,the evolution and transformation process between convection patterns are systematically described,and the variation laws of pressure drop of different flow patterns with time,gas-phase conversion velocity Js and liquid-phase conversion velocity Jl are drawn.The relationship between flow patterns and pressure drop is analyzed.The mechanism of action of core on gas-liquid two-phase flow is revealed,and the regulation process of wick on gas-liquid two-phase flow pattern is described.In this paper,the evolution and transformation process between convection patterns are systematically described.The variation laws of pressure drop,gas phase converted velocity Js and liquid phase converted velocity Jl under different flow patterns are given.The relationship between flow patterns and pressure drop is analyzed.The two-phase flow pattern and pressure drop characteristics of the smooth tube and the tube with mesh wick is experimented in a glass tube which inner diameter is 27 mm.The mechanism of action of mesh wick on gas liquid two-phase flow is revealed and the control process of mesh wick on gas liquid two-phase flow pattern is described.In the Operating range of this paper,when the conversion flow velocity of liquid phase Jl increases,the conversion flow velocity of gas phase Js decreases,the diameter of circular mesh wick increases,the mesh wick is suspended in the tube for 2 mm,the brass mesh wick is used to replace the stainless steel mesh wick and the V-shaped mesh wick is used to replace the circular mesh wick,the liquid phase diversion ratio ? will rise up differently.The mesh number and porosity of the mesh wick affects the capillary force and permeability of the mesh wick,and the capillary force and permeability together affect the liquid phase diversion ratio.The liquid phase diversion ratio of V-shaped mesh wick is larger at 90 ° opening angle than at 120 ° opening angle and 60 ° opening angle.The pressure drop in the tube is dominated by gas-phase fluid.The pressure drop in the tube increases nonlinearly with the increase of gas-phase converted velocity Js.The change of pressure drop in the tube is not obvious with the increase of liquid-phase converted velocity Jl.With the decrease of diameter,decrease of mesh number,increase of porosity,increase of V-shaped mesh wick opening angle and the substitution of V-shaped mesh wick for circular mesh wick,the pressure in the tube drop decreases.The different material of the mesh wick will not make the pressure drop change obviously.