| CPC F28F 1/40 (2013.01) | 2 Claims |
|
1. An inner spiral grooved tube, comprising:
a tube body; and
a plurality of grooves and a plurality of fins aligned in an inner circumferential direction of the tube body, wherein
the grooves and the fins are formed in a spiral along a longitudinal direction of the tube body,
an outer diameter of the tube body is 3 mm or more and 10 mm or less,
a number of the fins formed on an inner peripheral surface of the tube body is 30 to 60,
the inner spiral grooved tube is made of a metal,
a cross sectional shape of each of the fins in a cross section of the tube body has an isopod trapezoidal shape, an apex angle formed by sidewalls of the isopod trapezoidal shape being −2.5° or more and 2.5° or less,
a ratio h/f is 1.750 or more and 3.161 or less, h being a fin height and f being fin width,
a ratio c/f is 1.547 or more and 2.965 or less, c being a fin spacing between adjacent fins in the inner circumferential direction of the tube body,
an average obtained by summing the ratio h/f and the ratio c/f and dividing a sum in half is 2.4 or more and 2.6 or less,
the fins are arranged with an equal spacing in the inner circumferential direction of the tube body,
the tube body is made of aluminum or an aluminum alloy,
an average of the upper width and the lower width of the fin is 0.091 mm or more and 0.138 or less, and
the fin height is 0.227 mm or more and 0.392 mm or less.
|