A Computational Fluid Dynamic Study Of A Rectangular Micro-channel For Multiphase Flow (Vapor-liquid)

In recent years,microchemical technology has become a new development direction and research hotspot in chemical engineering.The main components of micro-chemical equipment are micro-channels with characteristic scales ranging from nanometer to micron,which are of great significance to the study of fluid heat and mass transfer in micro-channels.Water vapour evaporation and condensation are important in many engineering applications,such as thermal power plants,cooling systems,boiling water reactors,etc.In this paper,the influence of flow change on heat transfer characteristics of vertical rectangular microchannel heat exchanger was studied by using CFD(Computational Fluid Dynamics)software for numerical simulation.As an interface tracking method,The VOF method is suitable for flows with gas-liquid interface and can be resolved completely on the scale of discrete grid.Based on the computational fluid dynamics(CFD)method,creating geometry modeler,and meshing three-dimensional geometry,using VOF method within the rectangular microchannel heat exchanger on the behavior of fluid flow and heat transfer numerical simulation,and studied the transient response of the model,the heat transfer under changing flow rate,temperature,velocity and pressure distribution,etc.The calculation results,analyses the change flow channel size and inlet velocity will influence the performance of the system.The results show that decreasing the width and height of the channel or decreasing the inlet velocity can increase the condensation amount and thus increase the total heat exchange.However,a possible disadvantage is that the microchannels can be blocked by condensate,which will lead to a decrease in the overall heat transfer rate.In the simulation of this paper,the optimal heat transfer rate is obtained when the channel width is 200 microns,height is 100 microns and length is 1 cm.