Numerical Simulation Of The Flow Characteristics And Evaporative Heat Transfer Of Water Film In The Large Plate

In the third generation of advanced pressurized water reactor,the Nonactive containment cooling system has a key role in protecting the safety of nuclear power plants.Therefore,it is of great significance to study the flow characteristics and the heat transfer phenomenon of the water film in the annular channel formed by the outer wall surface of the safe shell and the air baffle.On the basis of the test bench for the flow of water film and evaporation heat transfer in the existing rectangular channel,which has the characteristics of large size and wide range of operation parameters,the flow distribution law of the water discharge film on the large plate under the condition of cold condition and the heat transfer of water film under different inlet water conditions and inlet air conditions was studied is studied by experiment,accumulated experiment data.Based on the experimental conditions,this paper established a CFD simulation scheme using Eulerian Wall Film model to conduct numerical study on the flow characteristics of water Film and evaporation heat transfer of water Film in large plate(5m and width 1.2m).In the simulation of water film flow characteristics,the comparison between the experiment and the numerical simulation through the water film coverage width and the average film thickness,the error is less than 15%,verifying the accuracy of the EWF numerical simulation scheme established in this paper.In addition,this scheme is used to simulate other test stands in the literature,and compared with the results of simulation scheme using VOF model,the proposed scheme has higher computational accuracy.On the basis of the test data,compared with numerical simulation results in different parameter Settings to determine the key parameters in the Eulerian Wall Film model in the numerical simulation scheme.Again through the result of experiment and numerical simulation error of the rate of evaporation,heat transfer and the comparison of Sherwood number is less than 20%,the numerical simulation program using EWF model is verified of accuracy to apply for water film evaporation heat transfer phenomenon.On this basis,the influence of various factors on the total heat transfer of water film evaporative heat transfer in large plate is analyzed.(1)The influence of the inlet water flow,the inlet wind temperature and the flat angle on the total heat exchange of the water film on the large plate is very small and negligible.(2)Inlet wind speed and inlet water temperature are the important factors that affect the total heat transfer of the water film evaporative heat transfer.(3)There is a turning point in the influence of inlet wind speed on total heat exchange,before the turning point,the greater the inlet wind speed,the greater the total heat exchange,and the lower the total heat exchange rate after the turning point.To sum up,in this paper,on the basis of experimental study,we set up and verified the CFD simulation scheme using Eulerian Wall Film model to simulate water film flow characteristics and water film evaporation heat transfer phenomena,the scheme has a small amount of computing grid,wide applicability,high calculation precision,can be used for all size of containment in the inland waters Film flow characteristics and heat transfer analysis,and for the optimization suggestions.