| 摘要 |
PURPOSE:To enable to prevent the heat-transmitting performance of heat exchanger from being lowered, by a method wherein a plurality of annular grooves inclined downwardly in the direction from the upstream side to the downstream side in respect of the flow of an external fluid are provided at appropriate intervals in the inside walls of heat-transmitting pipes placed in the vertical direction. CONSTITUTION:A condensed liquid 10 flowing downwards through descending heat-transmitting pipes 4a, 4b is cut by the annular grooves 8 having a triangular cross-section before the film thickness thereof is enlarged. Since the grooves 8 are inclined downwardly in the direction of from the upstream side B to the downstream side C in respect of the flow of the exteral fluid, the condensed liquid 10 in the grooves 8 on the upstream side B is washed away into a vertical groove 9 provided on the downstream side C, the film of the condensed liquid on the heat-transmitting wall on the upstream side B where local heat- transmitting rate is high becomes thinner, the heat-transmitting wall on the downward side C which does not contribute to the heat-transmitting efficiency can be utilized as a flowing-down passage, and the heat-transmitting performance of the heat exchanger is prevented from being lowered. |
