Boundary Heat Flux Inversion And Phase Interface Reconstruction Of Phase Change Heat Transfer System

Phase change heat transfer has been widely applied in metallurgy,casting,phase change temperature control,phase change thermal storage and biological freezing engineering technology fields.It is of great significance for the optimization design and operation control of the phase change heat transfer system to study the temperature field in the phase change material and the temporal and spatial evolution of the phase transition interfaceObtaining the boundary conditions of phase change heat transfer is the premise for establishing the temperature field of phase change heat transfer system and grasping the evolution rule of phase change interface.Because the heat flux of the internal boundary of the phase change heat transfer system is difficult to be measured directly,the inverse heat transfer method is used to reverse the boundary heat flow of the phase change heat transfer system and to reconstruct the temperature field of the heat transfer system and the evolution law of the phase transition interface,It is a more effective technical scheme.Based on the phase change heat transfer process of molten material reactors,the inversion of boundary heat flux and the reconstruction of phase boundary for two-dimensional phase change heat transfer are studied.The main work includes:(1)A mathematical model of two-dimensional phase change heat transfer process is established.Enthalpy method is applied to deal with latent heat of phase change in the heat transfer process.The finite volume method is used to discretize the heat conduction differential equations.Through numerical simulation experiments,the influence of thermal boundary conditions on the temporal and spatial evolution of the temperature field and phase interface of the heat transfer system is analyzed and the influence of grid partition on the simulation results is also discussed.(2)Based on the numerical simulation of two-dimensional phase change heat transfer process,the conjugate gradient method(CGM)is applied to establish the two-dimensional heat transfer inversion scheme for phase change heat transfer.Further,based on the inversion results of boundary heat flux,reconstruct the transient temperature field of phase change heat transfer system and study the temporal and spatial evolution rule of phase change interface.Through the numerical simulation test,the inversion results and the reconstruction results of the phase transition interface are obtained,and the feasibility of the inversion scheme is preliminarily verified.(3)On the basis of the above work,the boundary heat flux inversion and phase change interface reconstruction in the phase change process of molten steel reactor were studied.The influence of the initial guess value,the number of temperature measurement points and the temperature measurement error on the inversion results and the reformed temperature field are discussed through the simulation test.The simulation results show that the inversion results of the boundary heat flow have a certain dependence on the initial guess value,but for different initial guess values,the inversion model established in this paper can still obtain better inversion results.Within a certain range of temperature measurement error,the conjugate gradient method can get satisfactory inversion results.The proper increase of the number of measuring points can improve the accuracy of inversion.