Flow And Heat Transfer Characteristics Of Alkali Metal Liquid In A Pipe Filled With Inscribed Regular Polygon Porous Media

Flow and heat transfer characteristics of alkali metal liquid in a pipe filled with inscribed regular polygon porous media and segmented inscribed square porous media are numerically investigated based on the local thermodynamic equilibrium method.The tube wall is subjected to constant heat flux.Two flow conditions including laminar flow and turbulent flow are considered.The Darcy number varies in the range of10-6?Da?10.It is found that,1 For the case of continuous filling way and the two flow conditions,the Nusselt number increases as the number of sides of regular polygon increases when the Darcy number is not more than 10-4.However,there exists the best continuous regular polygon filling way namely the inscribed square filling way to make the Nusselt number maximum when the Darcy number is higher than 10-4.Meanwhile,for the two flow conditions,there is a critical Darcy number to make the performance evaluation criteria(PEC)first decreases then increases.The continuous filling way owned the best PEC for laminar flow is the inscribed continuous square filling way,while it is the inscribed continuous regular triangle filling way for turbulent flow.2 For the case of segmented inscribed square filling way and the two flow conditions,the average Nusselt number and the resistance coefficient increase as the filled ratio increases while decreases as the unit length increases.The variation trend of PEC is the same as before for the laminar flow.However,the PEC for the turbulent flow is basically the same among different segmented inscribed filling ways.Besides,there is a segmented filling way under which both the Nusselt number and the PEC are greater than the continuous filling way for laminar flow;yet,such a result is not obtained for turbulent flow.3 Comprehensive analysis shows that,both the inscribed continuous filling way and the segmented filling way can effectively enhance the flow and heat transfer characteristics for the case of laminar flow,but it does not work for the case of turbulent flow.