Study On Two Phase Fluid Distribution And Optimization In The Side Branch Pipe Of T-junction

The adjustment of energy structure around the world has greatly increased the demand for clean energy such as natural gas.Liquefied natural gas has the advantages of small volume and convenient transportation.The plate fin heat exchanger is the core device in the cold box which is the core device for natural gas liquefaction,and the uneven distribution of the flow distribution between the flow channels is an important problem that affects the efficiency of the system and the safety of production in its application.The gas-liquid uniformity of two-phase fluid entering the heat exchanger will directly affect the redistribution of header in heat exchangers,and further affect the flow distribution between the flow channels of the heat exchanger.In this paper,the numerical simulation method is used to study the methane gas and liquid two phases(temperature 135K and pressure 0.49MPa)in the T-junction tube of the heat exchanger.study on the foggy flow gas-liquid flow characteristics and two phase distribution law in branching conduits by numerical simulation.Studying on the influence of inlet velocity and droplet size on the phase distribution in side branch.According to the distribution law of two phases in the right angle T-junction,the optimal structure method of the bending angle T-junction is proposed.Through the simulation,it is proved that the distribution of gas-liquid is superior to the right angle T-junction.By changing the split ratio to simulate the different of gas-liquid distribution in three parallel conduits.Main conclusions are as follows:When the foggy two phases flow flows through the rightangle T-junction structure,the gas and liquid velocity slip will occur during the distribution,mainly in the x and y direction,in the x direction,the velocity of the liquid phase is bigger than the gas velocity,and in the y direction,the gas velocity is greater than the liquid velocity,resulting in the liquid phase mostly concentrated on the right side of the side branch,then the distribution of gas and liquid is uneven.Whirlpool is formed on the left side of the side branch due to fluid inertia,whirlpool will aggravate the uneven distribution of gas and liquid,and increase the pressure loss of side branch pipe,which causes uneven distribution of pressure,which is not conducive to the flow distribution of multi branch pipes in parallel.The degree of gas-liquid separation increases with the increase of gas liquid inlet velocity or droplet size.In view of the uneven distribution of gas and liquid in the rightangle T-junction side branch,the optimal structure of the bending angle T-junction is proposed.The gas-liquid distribution in the optimized T-junction side branch is obviously improved.It is found that the bending branch can obviously reduce the velocity of the fluid,reduce the swirl scale,uniform the pressure of the side branch,improve the carrying capacity of the gas relative liquid phase,and promote the uniform distribution of the gas and liquid in the side tube.When the three branch pipes are parallel,the swirling scale on the left side of the side branch decreases with the decrease of the split ratio,and the area with high liquid concentration gradually moved from the right side to the middle of the side branch pipe.The structure optimization of the T-junction under three kinds of split ratio is carried out.It is found that the optimization effect of the bending tube with the same bend radius is different,and the optimal bending radius should be gradually reduced with the decrease of the split ratio.