| 摘要 |
PURPOSE:To strengthen surface tension on the inner face of a tube, and to remarkably improve heat transfer performance as compared with a conventional heat transfer tube with inner grooves by increases in heat transfer area and turbulent flow by continuously or intermittently forming crests of height of 3/5 or less of the height of fins between grooves at partial or all grooves. CONSTITUTION:Grooves 11 each having 18 degrees of lead angle with respect to a tubular axis and fins 12 between the grooves 11 are alternately formed in large quantities on the inner face of a heat transfer tube 1, and crests 13 lower than the height of the fin 12 are continuously formed at the center of the bottom of each groove 11. The height of the crest 13 is set to 3/5 or less of the height of the fin 12, and desirably to 1/5 - 1/2. Since the heat transfer tube 1 has the crests 13 in the bottom of the groove 11, surface tension is strengthened in the groove 11 to prevent refrigerant liquid held in the groove 11 from flying out from the inner wall by the vapor of the refrigerant flowing in the tube 1. Accordingly, a dryout point is delayed to a high dryness to improve evaporating performance and to also improve condensing performance by increasing heat transfer area and turbulent flow effect. |
