Based on the principle of physical quantity synergy in the field of laminar heat transfer,and according to the models of zero equation and k-ε two equations for the turbulent flow,the synergy equations for both energ...Based on the principle of physical quantity synergy in the field of laminar heat transfer,and according to the models of zero equation and k-ε two equations for the turbulent flow,the synergy equations for both energy and momentum conservation in the turbulent heat transfer are established.The synergy regulation among heat flux,mass flow and fluid driving force,and the mechanism of heat transfer enhancement it reflects are revealed.The synergy principle of physical quantity in the thermal flow field is extended from laminar flow to turbulent flow.The principle is verified to be universal by the calculation of heat transfer enhancement in a tube with an insert of helical twisted tape.Thus,corresponding to the synergy relation among physical quantities in the turbulent flow field,the performance of convective heat transfer and flow resistance for the tubes with different heat transfer components and surface can be compared through theoretical and computational analysis,which thereby provides a guidance for designing heat transfer units and heat exchangers.展开更多
For laminar and turbulent convective heat transfer, the synergy among vectorial physical quantities of a fluid particle is analyzed to reveal the relation between the multi-field synergy mechanism and heat transfer en...For laminar and turbulent convective heat transfer, the synergy among vectorial physical quantities of a fluid particle is analyzed to reveal the relation between the multi-field synergy mechanism and heat transfer enhancement. Additionally, the efficiency evaluation criterion (EEC) is proposed to evaluate the overall performance of heat transfer enhancement. Meanwhile, using synergy angles α,β,,γ and η, a unified evaluation system and corresponding evaluation indexes for heat transfer enhancement are suggested. A model of a heat-transfer-enhanced tube inserted with poles in a triangular configuration is built, and a corresponding numerical simulation is conducted to verify the proposed evaluation system and criterion. The calculation results show that there is correlation between synergy angles reflecting the direction of heat transfer enhancement and evaluation criterion reflecting the effect of heat transfer enhancement. In the Re number range of 300-1800, the performance evaluation criterion PEC lies in the range of 1.2-2.3, but the efficiency evaluation criterion EEC lies in the range of 0.33-0.45.展开更多
基金supported by the National Basic Research Program of China (2007CB206903)the National Natural Science Foundation of China (50721005)
文摘Based on the principle of physical quantity synergy in the field of laminar heat transfer,and according to the models of zero equation and k-ε two equations for the turbulent flow,the synergy equations for both energy and momentum conservation in the turbulent heat transfer are established.The synergy regulation among heat flux,mass flow and fluid driving force,and the mechanism of heat transfer enhancement it reflects are revealed.The synergy principle of physical quantity in the thermal flow field is extended from laminar flow to turbulent flow.The principle is verified to be universal by the calculation of heat transfer enhancement in a tube with an insert of helical twisted tape.Thus,corresponding to the synergy relation among physical quantities in the turbulent flow field,the performance of convective heat transfer and flow resistance for the tubes with different heat transfer components and surface can be compared through theoretical and computational analysis,which thereby provides a guidance for designing heat transfer units and heat exchangers.
基金supported by the National Natural Science Foundation of China (51036003, 51021065)the National Basic Research Program of China (2007CB206903)
文摘For laminar and turbulent convective heat transfer, the synergy among vectorial physical quantities of a fluid particle is analyzed to reveal the relation between the multi-field synergy mechanism and heat transfer enhancement. Additionally, the efficiency evaluation criterion (EEC) is proposed to evaluate the overall performance of heat transfer enhancement. Meanwhile, using synergy angles α,β,,γ and η, a unified evaluation system and corresponding evaluation indexes for heat transfer enhancement are suggested. A model of a heat-transfer-enhanced tube inserted with poles in a triangular configuration is built, and a corresponding numerical simulation is conducted to verify the proposed evaluation system and criterion. The calculation results show that there is correlation between synergy angles reflecting the direction of heat transfer enhancement and evaluation criterion reflecting the effect of heat transfer enhancement. In the Re number range of 300-1800, the performance evaluation criterion PEC lies in the range of 1.2-2.3, but the efficiency evaluation criterion EEC lies in the range of 0.33-0.45.
