Numerical Simulation And Experimental Study On Gas-liquid Two-phase Flow Distribution Inside Header

The phenomenon of gas-liquid two-phase flow distribution is widespread in industrial heat exchanger.The characteristics of two-phase flow distribution not only affect the safe operation of the heat exchanger,but also have an important influence on the heat transfer efficiency and economic.Therefore,it is important to deeply study the characteristics of the two-phase distribution in the heat exchanger and get a more optimized geometry structure.The object of this paper is the intermediate header of a 10MW tower solar heat absorber.The header was modeled according to the design parameters,and a gas-liquid two-phase flow distribution experiment table is built to study the distribution characteristics of two-phase flow in four types of headers under different import conditions.Firstly,the two-phase flow distribution characteristics of the traditional header was studied.It was found that the two-phase flow distribution of the traditional headers is extremely uneven under the two flow patterns.For this purpose,the header with a flute tube structure was used to improve the two-phase flow distribution characteristics.Through experiments,it was found that under different flow patterns,the two-phase distribution in the new header is better than the traditional header,especially in the wavy flow pattern;The pressure drop in the inlet and outlet of header does not change much between the traditional headers and the new header;Changing the flute hole internal diameter of the flute tube has a great influence on the distribution characteristics of the header.The commercial software ANSYS CFX was used to explore the reason for the improvement of the two-phase flow distribution by adding a flute tube in header,The transient and inhomogeneous free surface model was selected to simulate the experimental process.The simulation results shows great agreement with the experimental data.Through the dynamic analysis of the volume fraction of water and the air/water velocity in each header,the reason for the difference in the distribution characteristics of the different structural headers are obtained.This study provides an idea for the optimization of the internal structure of the distribution header.