The numerical and experimental study was carried out for the discrete double-inclined ribs (DDIR) tube developed on the basis of the convective heat transfer field-coordination theory. The experimentally fitted relati...The numerical and experimental study was carried out for the discrete double-inclined ribs (DDIR) tube developed on the basis of the convective heat transfer field-coordination theory. The experimentally fitted relationships of heat transfer and resistance coefficients were given. The periodical change of the original surface specially designed in the DDIR tube induced multi-longitudinal vortex flow and enhanced heat transfer remarkably with less extra flow resistance.When Re=500—2300,heat transfer enhancement of the DDIR tube would be increased by 2.5—6.5 times with a resistance increase of 120%—300% compared to the laminar heat transfer of a circular tube (L/D=300) considering inlet effect. When Re=2300—104,heat transfer enhancement would be increased by 130%—240% with a resistance increase of 130%—220%.When Re=104—5×104,heat transfer enhancement would be increased by 110%—130% with a resistance increase of 220%—240% compared to the circular tube.There was no flow dead zone in the DDIR tube so fouling could be prevented in the tube.Its manufacture could be more efficient and low-cost, therefore it is a kind of heat transfer enhancement tube with excellent overall performance.展开更多
The uniformity principle of temperature difference field is a phenomenological principle,which has not been theoretically proved.For one-dimensional two-and three-stream heat exchangers,the extremum principle of entra...The uniformity principle of temperature difference field is a phenomenological principle,which has not been theoretically proved.For one-dimensional two-and three-stream heat exchangers,the extremum principle of entransy dissipation was used to optimize the heat transfer process by variational calculus.It was indicated that the temperature difference field between the hot and cold fluids should be completely uniform if the entransy dissipation reached a minimum for a given heat duty,or if the heat duty reached a maximum for a given entransy dissipation.So,the uniformity principle of temperature difference field of heat exchangers was primarily proved.展开更多
文摘The numerical and experimental study was carried out for the discrete double-inclined ribs (DDIR) tube developed on the basis of the convective heat transfer field-coordination theory. The experimentally fitted relationships of heat transfer and resistance coefficients were given. The periodical change of the original surface specially designed in the DDIR tube induced multi-longitudinal vortex flow and enhanced heat transfer remarkably with less extra flow resistance.When Re=500—2300,heat transfer enhancement of the DDIR tube would be increased by 2.5—6.5 times with a resistance increase of 120%—300% compared to the laminar heat transfer of a circular tube (L/D=300) considering inlet effect. When Re=2300—104,heat transfer enhancement would be increased by 130%—240% with a resistance increase of 130%—220%.When Re=104—5×104,heat transfer enhancement would be increased by 110%—130% with a resistance increase of 220%—240% compared to the circular tube.There was no flow dead zone in the DDIR tube so fouling could be prevented in the tube.Its manufacture could be more efficient and low-cost, therefore it is a kind of heat transfer enhancement tube with excellent overall performance.
文摘The uniformity principle of temperature difference field is a phenomenological principle,which has not been theoretically proved.For one-dimensional two-and three-stream heat exchangers,the extremum principle of entransy dissipation was used to optimize the heat transfer process by variational calculus.It was indicated that the temperature difference field between the hot and cold fluids should be completely uniform if the entransy dissipation reached a minimum for a given heat duty,or if the heat duty reached a maximum for a given entransy dissipation.So,the uniformity principle of temperature difference field of heat exchangers was primarily proved.
