Double pipe for heat exchanger

Patent metadata

Field	Value
Publication number	US-2023003456-A1
Application number	US-202017757109-A
Country	US
Kind code	A1
Filing date	Dec 8, 2020
Priority date	Dec 13, 2019
Publication date	Jan 5, 2023
Grant date	—

Abstract

A double pipe for a heat exchanger includes an inner pipe disposed in an outer pipe. In a straight-pipe portion of the double pipe, the inner pipe has a plurality of protruding parts extending in a helically offset manner along a longitudinal direction, an inner-circumferential surface of the outer pipe directly contacts the protruding parts, and outer-side channels are partitioned at a plurality of locations in a circumferential direction of the double pipe. The protruding parts are curved to protrude radially outward. In a cross section of the straight-pipe portion orthogonal to the longitudinal direction, the inner-circumferential surface of the outer pipe is circular, and an average value of D/L values of all the outer-side channels is 0.09-0.20, wherein D is defined as a maximum depth of each of the outer-side channels and L is defined as an arc length of each of the outer-side channels in the circumferential direction.

First claim

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; the protruding parts are helically offset in the longitudinal direction; 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 [mm] is defined as a maximum depth of each of the outer-side channels, L [mm] is defined as an arc length of each of the outer-side channels in the circumferential direction, and an average value of D/L values of all the outer-side channels is greater than 0.09 and less than 0.20.

2 . The double pipe according to claim 1 , wherein the outer pipe contacts the protruding parts owing to the outer pipe being swaged toward the inner pipe.

3 . The double pipe according to claim 1 , wherein, in the cross section of the straight-pipe part orthogonal to the longitudinal direction, a total of the arc lengths L of the outer-side channels has a length of 60% or more of a circumferential length C of a virtual circumscribed circle of the inner pipe.

4 . The double pipe according to claim 1 , wherein, in the straight-pipe part, the number of the protruding parts provided on the inner pipe is four or more and six or fewer.

5 . The double pipe according to claim 1 , wherein, in the straight-pipe part, a spiral angle of each of the protruding parts is 20° or more and 60° or less.

6 . The double pipe according to claim 1 , wherein, in the cross section of the straight-pipe part orthogonal to the longitudinal direction, a total of the arc lengths L of the outer-side channels has a length of 90% or less of a circumferential length C of a virtual circumscribed circle of the inner pipe.

7 . The double pipe according to claim 1 , wherein, in the cross section of the straight-pipe part orthogonal to the longitudinal direction, a total of channel cross-sectional areas of the outer-side channels is 5% or more and 30% or less of a channel cross-sectional area of the inner pipe.

8 . The double pipe according to claim 1 , wherein:
the inner pipe further comprises a plurality of helical recessed parts respectively provided between the protruding parts and curved so as to protrude toward an inner-circumference side; the helical recessed parts are helically offset in the longitudinal direction; and boundary parts are respectively formed in an angular shape between the protruding parts and the helical recessed parts.

9 . The double pipe according to claim 2 , wherein, in the cross section of the straight-pipe part orthogonal to the longitudinal direction, a total length of the arc lengths L of the outer-side channels is 60% or more of circumferential length C of a virtual circumscribed circle of the inner pipe.

10 . The double pipe according to claim 9 , wherein, in the straight-pipe part, four to six of the protruding parts are provided on the inner pipe.

11 . The double pipe according to claim 10 , wherein, in the straight-pipe part, a spiral angle of each of the protruding parts is 20°-60°.

12 . The double pipe according to claim 11 , wherein, in the cross section of the straight-pipe part orthogonal to the longitudinal direction, the total length of the arc lengths L of the outer-side channels is 90% or less of the circumferential length C of the virtual circumscribed circle of the inner pipe.

13 . The double pipe according to claim 12 , wherein, in the cross section of the straight-pipe part orthogonal to the longitudinal direction, a total of channel cross-sectional areas of the outer-side channels is 5%-30% of a channel cross-sectional area of the inner pipe.

14 . The double pipe according to claim 13 , wherein:
the inner pipe further comprises helical recessed parts respectively provided between the protruding parts and curved so as to protrude toward an inner-circumference side; the helical recessed parts are helically offset in the longitudinal direction; and boundary parts are respectively formed in an angular shape between the protruding parts and the helical recessed parts.

15 . A double pipe for a heat exchanger, comprising:
a double-pipe structure having an inner pipe disposed in an interior of an outer pipe, the double-pipe structure being configured to effect heat exchange between a fluid that flows in an interior of the inner pipe and a fluid that flows in outer-side channels defined between the inner pipe and the outer pipe, wherein: in a straight-pipe portion of the double pipe, the inner pipe comprises a plurality of protruding parts extending in a helically offset manner along a longitudinal direction, an inner-circumferential surface of the outer pipe directly contacts the protruding parts, and the outer-side channels are partitioned at a plurality of locations in a circumferential direction of the double pipe; the protruding parts are curved to protrude radially outward; and in a cross section of the straight-pipe portion orthogonal to the longitudinal direction, the inner-circumferential surface of the outer pipe is circular, and an average value of D/L values of all the outer-side channels is greater than 0.09 and less than 0.20, wherein D is defined as a maximum depth of each of the outer-side channels and L is defined as an arc length of each of the outer-side channels in the circumferential direction.

16 . The double pipe according to claim 15 , wherein, in the cross section of the straight-pipe portion orthogonal to the longitudinal direction, a total length of the arc lengths L of the outer-side channels is 60%-90% of circumferential length C of a virtual circumscribed circle of the inner pipe.

17 . The double pipe according to claim 16 , wherein, in the straight-pipe portion, four to six of the protruding parts are provided on the inner pipe.

18 . The double pipe according to claim 17 , wherein, in the straight-pipe portion, a spiral angle of each of the protruding parts is 20°-60°.

19 . The double pipe according to claim 18 , wherein, in the cross section of the straight-pipe portion orthogonal to the longitudinal direction, a total of channel cross-sectional areas of the outer-side channels is 5%-30% of a channel cross-sectional area of the inner pipe.

20 . The double pipe according to claim 19 , wherein:
the inner pipe further comprises helical recessed parts respectively provided between the protruding parts and curved so as to protrude radially inward; the helical recessed parts are helically offset in the longitudinal direction; and boundary parts are respectively formed in an angular shape between the protruding parts and the helical recessed parts.

Assignees

• Uacj Corp

Inventors

• Katahira Shiro
• Hata Tetsuro
• Nakamura Takuro

Classifications

• F28D7/106 Primary

  consisting of two coaxial conduits or modules of two coaxial conduits · CPC title

• F28F1/426

  the outside portions and the inside portions forming parts of complementary shape, e.g. concave and convex · CPC title

• F28F2210/06

  having walls comprising obliquely extending corrugations, e.g. in the form of threads · CPC title

• F16L9/18

  Double-walled pipes; Multi-channel pipes or pipe assemblies · CPC title

• F28F1/06

  crimped or corrugated in cross-section · CPC title