Fog Flow Distribution And Optimization Study In Parallel Branch Tube

The parallel branch tube is a device that connects multiple plate-fin heat exchangers.It is widely used in industrial equipment such as natural gas liquefied cooling boxes.The internal gas-liquid two-phase flow is difficult to match due to large differences in physical properties.It will affect the safety and economy of the equipment..In order to study the flow characteristics of fog flow in parallel branch pipe,the parallel branch pipe in natural gas liquefied cooler is used as the physical model,and methane in the fog flow state is used as the working material for numerical simulation.The influence of fluid properties and flow conditions on fluid flow characteristics in parallel branch pipelines is analyzed,and the optimized structure is proposed,which has certain guiding significance for optimizing fluid flow characteristics in parallel branch tubes.The influence of fluid temperature of the flow characteristics of fog flow in parallel branch tube is analyzed by using the Mixture model which is suitable for fog flow.It is found that with increasing temperature,the flow characteristics of the fog flow in single branch pipe and the whole system show the same change law.The separation of gas and liquid in the horizontal flow direction and vertical flow direction is reduced,and the turbulent dissipation rate increases.The distribution of liquid phase flow between single and multiple branch tubes is more uniform.Using the single factor analysis method to compare the influence of the main physical parameters of methane atoms fluid on the liquid phase distribution in the parallel branch tube,it is found that the liquid phase viscosity decreases with the increase of the fluid temperature in the single root branch tube,and the energy required for the gas and liquid phase to generate slippage is reduced.The liquid phase is easier to separate from the gas phase,and the increase of the vapor phase viscosity will weaken the slip,and the decrease of the liquid phase density and the increase of the gas phase density will reduce the inertial force between the two phases to facilitate the flow rate.With the increase of the fluid temperature,the liquid phase viscosity has little effect on the liquid phase flow distribution,and the liquid phase density,gas phase viscosity and gas phase density changes are all conducive to the liquid phase flow ratio,and the influence effect increases in turn.The effects of the operating conditions of the inlet fluid on the flow characteristics of the fog flow in the parallel branch pipe are studied.The inlet velocity of the supervisor increases,the difference between the two phases is increased by the inertial force,and the single branch tube and the entire system of the parallel branch pipe are studied.The separation of gas and liquid in the horizontal flow direction and the vertical flow direction is aggravated,and the turbulence dissipation rate is increased.The distribution of liquid phase flow between single branch and multiple branch tubes is more uneven.The particle size of the droplet increases,the smaller the contact surface of the gas and liquid phase,the reduced viscous force,and the separation of gas and liquid in the direction of horizontal flow and vertical flow in the single branch of the parallel branch pipe and in the entire system.The turbulent dissipation rate decreases.The distribution of liquid phase flow between single branch and multiple branch tubes is more uneven.The liquid volume fraction increases,the difference between the two phases is increased by the inertial force,and the gas and liquid separation of the fog flow in the horizontal flow direction and the vertical flow direction is slightly aggravated in the single branch tube and the entire system.Turbulence dissipation rate decreases.However,due to the increase of the liquid-phase adhesion force,the liquid-phase flow distribution in the single root branch pipe has almost no change,and the liquid-phase flow distribution between the entire system branch tubes is more uniform.It is found that the variation of fluid inlet velocity and droplet particle size has a great influence on the flow characteristics of fog flow in parallel branch tubes.Recognizing the mechanism of uneven distribution of fluids in parallel branch tubes,changing the junction between branch tubes and side branch tubes to a circular arc structure,and the smaller the curvature of the arc curvature,the farther away from the entrance,and establishing a new type of parallel branch tube structure for numerical calculation,To observe the optimization of the flow characteristics of fog flow in parallel branch pipe system,it is found that after the optimization of parallel branch pipe,The gas and liquid separation,the distribution of liquid flow between single branch and multiple branch pipe and the turbulent dissipation rate of the fog flow in the horizontal and vertical flow direction were obviously optimized.At the same time,it is found that the optimization of the flow characteristics of the fog flow in the branch pipe farthest from the entrance is minimal,which points out the direction for further optimizing the structure of the parallel branch pipe.By analyzing the optimal degree of the arc transition connection structure of parallel branch pipe to the liquid phase flow distribution under different operating parameters,it is found that it is more necessary to choose the parallel branch pipe structure of Arc transition connection when the entrance speed and droplet size are large from the general economic point of view.