Microchannel Gas Liquid Two Phase Flow And Mass Transfer

This thesis researched mainly flow pattern, pressure drop and mass transfer of gas-liquid two phase flow in microchannel, microchannels are horizontal.and their cross-section is circular.Firstly, nitrogen-water two phase flow flow pattern experiments in microchannels with respectively2.66mm,3.49mm,3.97mm inner diameter were taken, in order to investigate flow patterns of nitrogen-water two phase flow, meanwhile, investigate effects of microchannel inner diameter on gas-liquid two phase flow flow patterns and flow pattern maps; nitrogen-ethanol and nitrogen-0.2%PAM solution two phase flow experiments in microchannel with2.66mm inner diameter were taken and compared experimental result with corresponding nitrogen-water two phase flow experiment’s, in order to investigate effects of liquid phase surface tension and viscosity on gas-liquid two phase flow flow pattern and flow pattern maps; and flow pattern map acquired from experiment was compared with those in literature and Akbar et al’s flow pattern transition model, in order to check experimental results. Bubbly flow, slug flow, annular flow and dispersed flow are got in the experiment, channel inner diameter, liquid phase surface tension and viscosity affect markedly gas-liquid two phase flow flow patterns and flow pattern maps.Secondly, nitrogen-water two phase flow pressure drop experiments in microchannels with respectively2.66mm,3.49mm inner diameter were taken,in order to investigate effects of gas and liquid superficial velocities and channel diameters on gas-liquid two phase frictional pressure drop, the results show gas-liquid two phase frictional pressure drops in microchannels increase with the increase of gas and liquid superficial velocities and the decrease of channel diameters; The experimental results were compared with predicted values of homogeneous flow model and separated-phase model, and the results show L-M correlation of separated-phase model could predict better gas-liquid two phase frictional pressure drops in microchannels than homogeneous flow model.Finally, the volumetric mass transfer coefficient KGa between gas and liquid in slug and dispersed flow with2.66mm channel diameter was measured by having carbon dioxide of low concentration absorbed by sodium hydroxide solution,and the interfacial area was forecasted and compared with that in macroscopic system according to the pseudo-first-order reaction in the experiment and KGα got. The result shows that KGα increases and the increase rate slows down with the increase of superficial gas velocity, while KGα increases and the increase rate does not slow down with the increase of superficial liquid velocity; interfacial area in the experiment is as high as2436m2/m3; interfacial area in microchannel is larger1-2orders of magnitude than traditional gas-liquid contact equipments,and mass transfer effect is better than that in macroscopic system.