Steel industry is high energy-consuming industry, and its waste?heat recovery is critically?important for energy utilization. In this study, pipeline bundle is used to enhance heat transfer in?waste?heat recovery devi...Steel industry is high energy-consuming industry, and its waste?heat recovery is critically?important for energy utilization. In this study, pipeline bundle is used to enhance heat transfer in?waste?heat recovery device,?and?associated gas-solid heat transfer and energy utilization performance with different pipeline arrangement, pipe diameter and shape of internal component are further analyzed. The temperatures of gas and particle in device with pipeline bundle periodically fluctuate in horizontal direction, and those in staggered system distribute more uniformly than those in paralleled system. Compared with paralleled device, exergy and waste heat utilization efficiency of staggered device have been improved, and they are both higher than?those without pipeline. As pipe diameter increases, exergy and waste heat utilization efficiency first increases and then decreases, and they reach the maxima with optimal pipe diameter.?As the width of internal component keeps constant, influence of its shape on heat transfer is very little.展开更多
In this paper, the control volume method is used to establish the general expression of entropy generation due to combined convective heat and mass transfer in internal and external fluid streams. Theexpression accoun...In this paper, the control volume method is used to establish the general expression of entropy generation due to combined convective heat and mass transfer in internal and external fluid streams. Theexpression accounts for irreversibilities due to the presence of heat transfer across a finite temperaturedifference, mass transfer across a finite difference in the chemical potential of a species, and due toflow friction. Based on the assumption of local thermodynamic equilibrium, the generalized form ofthe Gibbs equation is used in this analysis. The results are applied to two fundamental problems offorced convection heat and mass transfer in internal and external flows. After minimizing the entropygeneration, useful conclusions are derived that are typical of the second law viewpoint for the definitionof the optimum operation conditions for the specified applications, which is a' valuable criterion foroptimum design of heat and fluid flow devices.展开更多
A numerical study of fluid flow and convective heat transfer in a plate channel filled with solid (metallic)particles is presented in this paper.The study uses the thermal equilibrium model and a newly developed numer...A numerical study of fluid flow and convective heat transfer in a plate channel filled with solid (metallic)particles is presented in this paper.The study uses the thermal equilibrium model and a newly developed numerical model which does not assume idealized local thermal equilibrium between the solid particles and the fluid.The numerical simulation results are compared with the experimental data in reference[2].The paper investigates the effects of the assumption of local thermal equilibrium versus non-thermal equilibrium,the thermal conductivity of the solid particles and the particle diameter on convective heat transfer.For the conditions studied,the convective heat transfer and the temperature field assuming local thermal equilibrium are much different from that for the non-thermal equilibrium assumption when the difference between the solid and fluid thermal conductivities is large. The relative values of the thermal conductivities of the solid particles and the fluid also have a profound effect on the temperature distribution in the channel.The pressure drop decreases as the particle diameter increases and the convective heat transfer coefficient may decrease or increase as the particle diameter increases depending on the values of ε,λs,λf,λd,αv, ρu.展开更多
In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium...In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium model. The numerical simulation results are compared with experimental data. The difference between convection heat transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of convection heat transfer of air or water in packed beds using the local thermal non equilibrium model and the variable porosity model agrees well with the experimental data. The convection heat transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of convection heat transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.展开更多
文摘Steel industry is high energy-consuming industry, and its waste?heat recovery is critically?important for energy utilization. In this study, pipeline bundle is used to enhance heat transfer in?waste?heat recovery device,?and?associated gas-solid heat transfer and energy utilization performance with different pipeline arrangement, pipe diameter and shape of internal component are further analyzed. The temperatures of gas and particle in device with pipeline bundle periodically fluctuate in horizontal direction, and those in staggered system distribute more uniformly than those in paralleled system. Compared with paralleled device, exergy and waste heat utilization efficiency of staggered device have been improved, and they are both higher than?those without pipeline. As pipe diameter increases, exergy and waste heat utilization efficiency first increases and then decreases, and they reach the maxima with optimal pipe diameter.?As the width of internal component keeps constant, influence of its shape on heat transfer is very little.
文摘In this paper, the control volume method is used to establish the general expression of entropy generation due to combined convective heat and mass transfer in internal and external fluid streams. Theexpression accounts for irreversibilities due to the presence of heat transfer across a finite temperaturedifference, mass transfer across a finite difference in the chemical potential of a species, and due toflow friction. Based on the assumption of local thermodynamic equilibrium, the generalized form ofthe Gibbs equation is used in this analysis. The results are applied to two fundamental problems offorced convection heat and mass transfer in internal and external flows. After minimizing the entropygeneration, useful conclusions are derived that are typical of the second law viewpoint for the definitionof the optimum operation conditions for the specified applications, which is a' valuable criterion foroptimum design of heat and fluid flow devices.
文摘A numerical study of fluid flow and convective heat transfer in a plate channel filled with solid (metallic)particles is presented in this paper.The study uses the thermal equilibrium model and a newly developed numerical model which does not assume idealized local thermal equilibrium between the solid particles and the fluid.The numerical simulation results are compared with the experimental data in reference[2].The paper investigates the effects of the assumption of local thermal equilibrium versus non-thermal equilibrium,the thermal conductivity of the solid particles and the particle diameter on convective heat transfer.For the conditions studied,the convective heat transfer and the temperature field assuming local thermal equilibrium are much different from that for the non-thermal equilibrium assumption when the difference between the solid and fluid thermal conductivities is large. The relative values of the thermal conductivities of the solid particles and the fluid also have a profound effect on the temperature distribution in the channel.The pressure drop decreases as the particle diameter increases and the convective heat transfer coefficient may decrease or increase as the particle diameter increases depending on the values of ε,λs,λf,λd,αv, ρu.
基金Supported by the National Outstanding Youth Fundfrom the National Natural Science Foundation of China( No.5 0 0 2 5 617) and the Major State Basic ResearchDevelopment Program( No.G19990 3 3 10 6)
文摘In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium model. The numerical simulation results are compared with experimental data. The difference between convection heat transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of convection heat transfer of air or water in packed beds using the local thermal non equilibrium model and the variable porosity model agrees well with the experimental data. The convection heat transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of convection heat transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.
