Study On Near-infrared Absorption Spectrum And Flow Measurement Model Of Gas-liquid Two-phase Flow In Inner And Outer Tubes

Two-phase flow is widely used in many industrial applications,such as chemical reactor,boilers,electronics cooling devices and nuclear reactors.The application of multi-phase flow industrial system involves the wide range and the importance of application make the research work develop rapidly in this field and has become a frontier science with great concern at home and abroad.Differential pressure flowmeter is one of the most widely used flowmeters in two-phase flow measurement,and it is recognized as a kind of flowmeter which can work stably in different flow patterns.Therefore,some domestic and foreign experts set up a series of classical two-phase flow measurement model around the differential pressure flowmeter,but it is found that most of these models depend on the mass air rate which is another important parameter of gas-liquid two-phase flow.Therefore,the differential pressure flowmeter and other phase measurement instruments or technologies are often used to measure the flow rate.In this paper,the differential pressure flowmeter and near infrared spectroscopy technology are combined to establish the differential pressure-infrared measurement device.The slug flow in the vertical direction,bubble flow and the transition flow pattern between them are studied.A phase holdup measurement model and a flow measurement model are established and suitable for three flow pattern.First of all,there are positive and negative flow ways because of the structural characteristics of internal and external for the differential pressure flowmeter.Combined with the CFD simulation and experimental verification,we found that the differential pressure signal got in reverse circulation mode is larger and the pressure loss ratio is smaller,this is more worthy to study.The real flow calibration of differential pressure flowmeter is carried out base on this.Secondly the calculation model of liquid phase volume fraction is established base on the average value of the four channel near infrared signal.The maximum relative error of the model is about 6.03% and the range of application is 0.4~10m3/h for the liquid phase,0.12~0.6m3/h for the gas phase.Finally,two model for calculating the discharge coefficient of liquid phase and Froude number are established base on two differential pressure signal.And calculate the single liquid mass flow,the maximum relative error is 4.89% and 4.96% respectively,the scope of application: Frl:0.08~2.02,XLM-l:0.0002~0.0492,The model involves three kinds of vertical flow patterns which are the bubbly flow,slug flow and the flow pattern between the bubbly and slug flow.