| 摘要 |
PURPOSE:To improve a tube evaporation heat transfer rate and a tube condensation heat transfer rate in a low flow rate region of a heat exchange medium by setting the sectional area of the groove part of a rectangular cross section of a heat transfer tube several times the section of adjacent crest part. CONSTITUTION:In the rectangular cross section of a heat transfer tube 1, the sectional area S1 of a groove 2 is set 2-5 times the sectional area S2 of the crest 3, and the outside diameter D of the heat transfer tube 1 is selected to be as small as 8mm or less to increase the tube flow rate of the heat exchange medium in a low flow rate region, to promote a turbulent low to prevent laminar flow. Further, a groove bottom width W1 sufficient for lowering the retention height (f) of the condensate 4 of a heat exchange medium is imparted. By doing so, no remarkable performance lowering is found in the tube condensation transfer rate of the heat transfer tube even in a low speed flow region of the heat exchange medium. With the tube evaporation heat transfer rate, the performance is improved as the flow rate becomes low in the low speed flow region of the heat exchange medium. |
