| Gas-liquid two-phase flow is widely existed in industrial equipment,and the uniformity of the two-phase flow distribution inside the header is great significance to the safe operation and heat exchange efficiency of heat exchange equipment.Therefore,the research on the geometric structure and flow characteristics of the two-phase flow header is significance for overcoming the uneven flow distribution of parallel channels and improving the operation safety and economy of heat exchange equipment.Aiming at the uneven distribution of gas-liquid two-phase flow in the traditional header,this paper builds a visual experimental platform to study the influence of different experimental conditions and different geometric structures on the two-phase flow distribution in the header.The paper carried out the experimental investigation on the traditional header and the flute-tube header under different working conditions.The results of the investgation found that the flute pipes inside the header will significantly improve the two-phase flow distribution of parallel branch channels in the header.The branch channel flow ratio is near to one.The branch channel standard deviation(STD)is significantly reduced,indicating that the uniformity of flow distribution has been significantly improved.The paper uses ANSYS CFX software to numerically simulate the two-phase flow distribution inside the header.Transient model is used and the same boundary conditions as the experimental process are set.Obtain the state of the two-phase flow in the header,the cloud diagram of the gas-liquid two-phase volume fraction and the vector diagram of the cross-sectional velocity at the key position.It is found by comparison that the gas-liquid two-phase movement in the header is periodic,and there is a vortex in the sleeve area of the flute tube,which can effectively improve the two-phase flow distribution of the parallel branch pipe.In order to verify the reliability of the numerical simulation,high-speed photography is appled to record the process of two-phase flow distribution under reference working conditions.Combined with numerical simulation,it is found that the use of flute-shaped pipe inside header improves the uniformity of the two-phase flow distribution.By comparing the results with high-speed photography and numerical simulation.it is found that the numerical simulation is consistent with the high-speed photography process,reflecting the reliability of the numerical simulation.The study found that the main factor affecting the uneven distribution of liquid flow in the traditional header is the gas flow rate,and the process of gas-liquid two-phase interaction has changed significantly after the installation of the flute pipe inside header.The increase of the contact area solves the problem that some gas-liquid two-phases cannot directly contact and the end of the header return.At the same time,the flow velocity affects the bubble diameter when the gas flows out of the flute pipe.This paper uses a combination of experiment,numerical simulation and high-speed photography to study the flow field and phase separation inside the two-phase flow header.The research results show that three methods can be used to obtain the gas-liquid interaction law inside the two-phase flow header and the flow distribution mechanism of the two-phase flow in the flute pipe.This has a reference guidlines for two-phase flow distribution improvement inside header. |
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