Numerical Simulation Of Heat Transfer Of Gas-Liquid Tow-Phase Taylor Flow In Microchannel

In recent years,microchannel reactors have been widely used in aerospace engineering,biological engineering,chemical engineering,and microelectronics engineering.With the further development of technology,various fields have put forward higher requirements for heat exchangers.Microchannel heat exchange is a new type of efficient heat exchange technology.Its advantages such as safe and reliable operation,high heat exchange efficiency,small footprint,and compact structure make it a research hotspot at home and abroad.With the widespread use of micro heat exchange equipment in heat exchange,microelectronics,microcomputer systems,and chip experiments,the problem of micro-scale heat transfer has also become the focus of research on micro heat exchangers.The basic flow pattern of the gas-liquid two-phase flow in the circular microchannel,the apparent velocity range of the gas and liquid inlets forming Taylor flow,and the heat transfer of Taylor flow in microchannel are studied by the method of computational fluid dynamics.In this paper,a two-dimensional model of a circular microchannel with a diameter of 1.0mm is carried out.The model uses a standard quadrilateral meshing method,and the mesh is refined at the gas-liquid interface.The computational fluid dynamics simulation software is used for simulation calculations.Four basic flow patterns of gas-liquid two-phase flow formed by water and nitrogen are calculated by simulation.The velocity of the inlet gas and liquid phases forming the Taylor flow when the gas and liquid phases are methanol-nitrogen,water-nitrogen,and ethylene glycol-nitrogen are simulated,and the obtained data are compared with the previous empirical data.Establishing an appropriate gas-liquid two-phase Taylor flow calculation model,fix the inlet velocities of the gas and liquid phases.Methanol,water,and ethylene glycol are used as the liquid phase fluids in the Taylor flow,respectively.The simulation results are used to analyze the influence of liquid-phase fluids with different physical parameters on bubble morphology,bubble generation frequency and flow field distribution in Taylor flow.The Nusselt number is used to characterize the heat transfer in the microchannel.In the case of the inlet velocity of the gas and liquid phases is fixed,the wall heat flux is constant.When methanol-nitrogen and water-nitrogen are Taylor flow,the average Nusselt number is 2.2 and 2.4 times of its single-phase flow,respectively.The average Nusselt number when ethylene glycol-nitrogen is Taylor flow is 0.74 times that of ethylene glycol single-phase flow.Not all liquid phase fluids have much better heat transfer performance than single phase flow when forming Taylor flow in microchannel.