US 12,111,117 B2
Double pipe for heat exchanger
Shiro Katahira, Tokyo (JP); Tetsuro Hata, Tokyo (JP); and Takuro Nakamura, Tokyo (JP)
Assigned to UACJ CORPORATION, Tokyo (JP)
Appl. No. 17/757,109
Filed by UACJ Corporation, Tokyo (JP)
PCT Filed Dec. 8, 2020, PCT No. PCT/JP2020/045693
§ 371(c)(1), (2) Date Jun. 9, 2022,
PCT Pub. No. WO2021/117725, PCT Pub. Date Jun. 17, 2021.
Claims priority of application No. 2019-225888 (JP), filed on Dec. 13, 2019.
Prior Publication US 2023/0003456 A1, Jan. 5, 2023
Int. Cl. F28D 7/10 (2006.01); F28F 1/06 (2006.01); F28F 1/08 (2006.01); F28F 1/42 (2006.01); F16L 9/18 (2006.01)
CPC F28D 7/106 (2013.01) [F28F 1/426 (2013.01); F16L 9/18 (2013.01); F28F 1/06 (2013.01); F28F 1/08 (2013.01); F28F 2210/06 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A double pipe for a heat exchanger having a double-pipe structure, in which an inner pipe is disposed in an interior of an outer pipe, to effect heat exchange between a fluid that flows in an interior of the inner pipe and a fluid that flows between the inner pipe and the outer pipe, wherein:
in a straight-pipe part of the double pipe, the inner pipe comprises a plurality of protruding parts extending in a longitudinal direction and curved to protrude toward an outer-circumference side and a plurality of helical recessed parts respectively provided between the protruding parts and curved so as to protrude toward an inner-circumference side;
the protruding parts are helically offset in the longitudinal direction;
the helical recessed parts are helically offset in the longitudinal direction;
boundary parts are respectively formed in an angular shape between the protruding parts and the helical recessed parts;
in a cross section of the straight-pipe part orthogonal to the longitudinal direction, an inner-circumferential surface of the outer pipe is circular;
in the straight-pipe part, the inner-circumferential surface of the outer pipe contacts the protruding parts of the inner pipe, and outer-side channels, which are partitioned at a plurality of locations in a circumferential direction of the double pipe, are formed between the outer pipe and the inner pipe; and
in the cross section of the straight-pipe part orthogonal to the longitudinal direction, D is defined as a maximum depth of each of the outer-side channels in millimeters, L is defined as an arc length of each of the outer-side channels in the circumferential direction in millimeters, and an average value of D/L values of all the outer-side channels is greater than 0.09 and less than 0.20.