| 摘要 |
PROBLEM TO BE SOLVED: To improve a heat transfer performance at the time when a mixed refrigerant is used and an in-pipe heat transfer rate at the time of evaporation, in particular, by a method wherein the ratio between a helix angle of a groove to the axis of a pipe and a sectional area of a refrigerant passage is made a specific value. SOLUTION: A sectional area Sr of a refrigerant passage is obtained by adding the total amount of sectional areas 7 of grooves to the area of a circle obtained from the inside diameter 2 of a pipe and expressed as an envelope circle of crests, and it is the area of a cross section to the pipe axis inside the pipe through which a refrigerant can flow. In a heat transfer pipe with internal grooves which is used for air conditioning equipment for cooling and heating wherein a mixed refrigerant is used as a working fluid, the ratioθ/Sr between a helix angleθdeg. of the groove to the pipe axis and the sectional area Sr mm of the refrigerant passage is made 0.5 or above. A crest angleαof a fin in the cross section to the pipe axis is made 30 deg. or below. According to this constitution, lowering of a heat transfer performance due to the use of the mixed refrigerant can be prevented and the heat transfer performance standing comparison with that in the use of a single refrigerant can be obtained.
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