Turbulent Heat Transfer Calculation In Fuel Assembly Of Lead Bismuth Eutectic Reactor

Lead bismuth eutectic(LBE)reactors are a special type of reactor.First of all,it can be applied to reducing the harm of nuclear waste,improving the utilization rate of fuel and reducing waste pollution by transmutation technology.At the same time,it meets the requirements of small modular reactor.The flow in the engineering is mainly turbulence,because of the strong mixing of turbulent flow,which can enhance the heat transfer effect.Turbulent flow is an extremely complex flow,and LBE is a very special medium.As a liquid metal,it has a small Prandtl number,a larger specific heat capacity.Meanwhile,a lower melting point.Studying the turbulent heat transfer of LBE has great value and significance to nuclear power safety.According to the physical data and formula of LBE,the formulas and standard number of calculation documents are prepared.The calculation model of liquid metal was selected by comparison and calculation,and the model was optimized by comparison with the experimental data.The grid files of the whole channel,inner channel,edge channel and angle channel are built based on the structure and parameters of the core.First the numerical computation have been done.Import the files into the Fluent for calculation,The velocity and temperature simulation results are obtained.The average temperature in normal conditions is 587K.The heat exchange of different locations and channels is compared.The average temperature of inner channel,edge channel and angle channel is 610K,574K and 568K.The speed and temperature distribution under different working conditions are obtained by changing the boundary conditions.When the velocity increases,the heat exchange decreases.Heat exchange enhanced when inlet temperature rises or power increased.That is consistent with the results of grey theory calculation.The calculation results also show that,in the selected range,the power affects>inlet temperature affects>inlet velocity affects.In natural circulation,the height affects>temperature affects>tube diameter affects.In the analysing of the mechanism,It's obtained the LBE has very low prandtl number,the molecular heat transfer in the whole heat transfer process is large.In the process of heating,the fluid's change of density is small.Compared with conventional fluid,the thermal resistance and heat disturbance are smaller,so the natural circulation capacity is weaker.