| Title |
Falling Film Heat Transfer on a Horizontal Single Tube |
| Keywords |
Falling - film heat transfer ; 유하액막 열전달 ; Lithium bromide solution ; 리튬브로마이드 수용액 ; Smooth tube ; 평활관 ; Knurled tube ; 널링관 |
| Abstract |
Falling film heat transfer analyses with aqueous lithium bromide solution were performed to investigate the transfer characteristics of the copper tubes.Finned(knurled) tube and a smooth tube were selected as test specimens.Averaged generation fluxes of water and the heat transfer performances(heat flux, heat transfer coefficient) were obtained.The results of this work were compared with the data reported previously.
As the film flow rate of the solution increased, the generation fluxes of water decreased for both tubes.The reason is estimated by the fact that the heat transfer resistance with the film thickness increased as the film flow rate increased.The effect of the enlarged surface area at the knurled tube was supposed to be dominant at a small flow rate.The generation fluxes of water increased with the increasing degree of tube wall superheat.Nucleate boiling is supposed to occur at a wall superheat of 20 K for a smooth tube, and at 10 K for a knurled tube. The heat transfer performance of the falling film was superior to pool boiling at a low wall superheat below 10 K for both tubes tested.The knurled tube geometry showed good performance than the smooth tube, and the increased performance was mainly came from the effect of the increased heating surface area. |