| 摘要 |
PROBLEM TO BE SOLVED: To improve the heat transfer performance by engraving the groove disposed relatively lower deeply and the groove disposed above shallowly in the case of passing refrigerant by engraving the plurality of grooves on the inner surface and installing them in the lateral direction. SOLUTION: The grooves 2 provided on the inner surface of a heat transfer tube 1 are low in the height of the same section at the upper part and high at the lower part. That is, when the angle from the lowermost point A of the gravity isθand the height of the groove 2 is h, the height of the groove 2 is lowered from the lowermost point A of the gravity as separating in the direction of the opposite gravity. Accordingly, the thickness of the liquid film of the refrigerant in the groove 2 of the direction for operating the gravity in the refrigerant condensing step is lowered to improve the heat transfer rate, and the contact area of the refrigerant liquid with the inner surface of the tube 1 in the direction of operating the gravity in the refrigerant evaporating step is increased, and hence the heat transfer performance can be improved.
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