Study On Phase Volume Fraction Of Gas-liquid Two-phase Flow Detection Technology Based On Four Groups Of Near-infrared Detection Device

Gas-liquid two-phase flow widely exists in the power plant,nuclear reactors,petrochemical industry,aerospace,waste heat utilization,energy-saving equipment,refrigeration and other fields.Section phase holdup is the most important parameters of two-phase flow,a lot of research has been conducted so far.In the four types of two-phase pipe flow(gas-liquid,gas-solid,liquid-liquid and liquid-solid),the gas-liquid two-phase flow is the most complex.This is due to the presence of gas-liquid two-phase flow in a deformable interface,which is highly compressible gas phase.Different phase holdup ratio can be transformed into different flow patterns,so the gas-liquid two-phase flow in the phase holdup has become an important research.The traditional detection method is based on the principle of electrical phase using transformation of dielectric constant,which is low price and cannot satisfy the needs of online measurement yet,so,this paper detection phase holdups,by using near infrared spectral absorption technology.Near-infrared light is a kind of between the visible(VIS)and infrared(IR)between the electromagnetic wave,in the gas-liquid two phase flow,gas and water has its own characteristic absorption peak.Under different flow patterns,under the specific wavelength,can be very good to distinguish the gas liquid two phase.The main task is to design a monitoring systems using near infrared spectroscopy and detection phase volume fraction.Design of the experiment conduit holes 8 with an opaque four transmissions and reception.The system choice 980 nm emission sources and the corresponding infrared absorption detectors,they are located on both sides of the pipeline,the signal of near-infrared light through the pipe of gas-liquid two-phase flow.The signal be received by the near-infrared receives,from the near-infrared receiver the received signal is extracted near-infrared light intensity signal and the intensity signal is extracted after converting the induced voltage signal output.High-frequency data acquisition card for data acquisition,simultaneous measurement of four different locations probes under different flow patterns,and in the process of doing the experiment by adding high-speed video cameras,the flow pattern can be dynamically displayed clear and intuitive,help better understand the gas-liquid two-phase flow patterns under different gas-liquid distribution.The dynamics experiments of bubbly flow,stratified flow and annular flow were made on the horizontal pipe.The dynamic output voltage were obtained at different flow patterns,different operating point and different locations.And to do the voltage value and the steady state initial value ratio,according to the characteristics of the different ratio,can distinguish the flow pattern.The phase holdup of three flow patterns were fitted,The maximum error in the bubbly flow is ±0.25%,The maximum error in the stratified flow is ±18%,The maximum error in the annular flow is ±6%.