Investigation On Heat Transfer And Entropy Production In Tube Filled With Layered Or Partially Filled Porous Media Under Local Non-thermal Equilibrium Condition

The forced convection heat transfer in a tube filled with double-layer porous medium and in a tube partially filled with porous media is analytically investigated.Hydrodynamically and thermally fully developed conditions are assumed in the tube.The wall of the tube is exposed to constant heat flux.The Darcy-Brinkman model is utilized to describe the fluid flow,and the local thermal non-equilibrium condition is employed to establish the energy equations.In the study of the tube filled with double-layer porous medium,the analytically solutions for velocity and temperature fields are derived and validated in extreme situation.In order to study the heat transfer enhancement performance and irreversibility of the tube filled with double-layer porous medium,the analytical solutions of the Nusselt number,the local entropy generation rates and the total entropy generation rate of the tube are also deduced.On these foundations,the influences of Darcy number,Biot number,dimensionless filling ratio and other relevant parameters on the heat transfer enhancement performance and irreversibility of the tube filled with double-layer porous medium are analyzed.The results indicate that selecting an appropriate layered filling method,the heat transfer enhancement performance of the tube filled with double-layer porous medium is significantly better than that of the tube filled with corresponding single-layer porous media,and the entropy generation is smaller than that of the tube filled with corresponding single-layer porous media.In the study of the tube partially filled with porous media,the analytical solutions of velocity field,temperature distribution,friction factor,Nusselt number and entropy generation are obtained by using stress jumping interface condition.The analytical solution of entropy generation in a tube partially filled with porous media is given,which fills the blank of previous research.The influence of the stress jumping coefficient and other related parameters on the performance evaluation criterion(PEC)and irreversibility in the tube is discussed.The results show that the proper partial filling method can effectively increase the heat transfer of the tube without causing too much flow resistance.In addition,as the dimensionless filling ratio changes,the Nusselt number and the total entropy generation have maximum and minimum values,respectively,and the value of the filling ratio that maximizes the Nusselt number and the value of the filling ratio that minimizes the entropy production varies with different parameters such as the Darcy number.