E211 EVAPORATION OF WATER IN AN AQUEOUS LITHIUM BROMIDE SOLUTION FLOWING OVER A HORIZONTAL TUBE(Evaporation-2 and others)

概要

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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 a test specimens. Averaged generation fluxes of water and the heat flux 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 due to the fact that the heat transfer resistance with the film thickness 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. The increased performance of the knurled tube was supposed to mainly came from the effect of the increased heating surface area.
一般社団法人日本機械学会の論文
2000-10-01