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US4044797A
Expired / Lapsed
US
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Heat transfer pipe
Assignee: Hitachi Ltd
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Filing: 1975-11-14
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Granted: 1977-08-30
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Expires: 1995-11-14
Abstract
Abstract A heat transfer pipe for use in a heat exchanger such as air conditioner, freezer and boiler, wherein grooves are formed in the inner wall surface of the pipe, which are by far finer in size than the grooves that have been provided for the purpose of increasing the heat transfer area in general, and slanting relative to the axis of pipe, to thereby improve the heat transfer rate without increasing the pressure loss caused to the fluid flowing through the pipe.
Inventors
- 👤 Kunio Fujie
- 👤 Masaaki Itoh
- 👤 Tamio Innami
- 👤 Hideyuki Kimura
- 👤 Wataru Nakayama
- 👤 Takehiko Yanagida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:59
CPC Classifications
F; F28; F28F; F28F13/00; F28F13/18; F28F13/185; F28F13/187; F28F1/00; F28F1/10; F28F1/40
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
83 words
In a heat transfer pipe for forced convection boiling or condensing the improvement comprising said heat transfer pipe being formed on its inner wall surface with grooves having a depth from the wall surface to their bottoms in the range between 0.02 and 0.2 millimeters, a pitch between the adjacent grooves in the range between 0.1 and 0.5 millimeters, and an angle of inclination with respect to the axis of the heat transfer pipe arranged between 4° and 15° or 165° and 176°.
Claim 2
Dependent Claim
83 words
In a heat transfer pipe for forced convection boiling or condensing the improvement comprising said heat transfer pipe being formed on its inner wall surface with grooves having a depth from the wall surface to their bottoms in the range between 0.02 and 0.2 millimeters, a pitch between the adjacent grooves in the range between 0.1 and 0.5 millimeters, and an angle of inclination with respect to the axis of the heat transfer pipe arranged between 4° and 15° or 165° and 176°.
Claim 3
Dependent Claim
29 words
A heat transfer pipe as claimed in claim 1, wherein the angle of inclination of said grooves with respect to the axis of the heat transfer pipe is 7°.
Claim 4
Dependent Claim
21 words
A heat transfer pipe as defined in claim 1, wherein the grooves narrow from the inner wall surface to their bottoms.
Claim 5
Dependent Claim
16 words
A heat transfer pipe as defined in claim 3, wherein the grooves are V-shaped in section.
Claim 6
Dependent Claim
20 words
A heat transfer pipe as defined in claim 4, wherein the apex angle of groove is no more than 90°.
Claim 7
Dependent Claim
20 words
A heat transfer pipe as defined in claim 4, wherein the apex angle of groove ranges from 30° to 60°.
Claim 8
Dependent Claim
16 words
A heat transfer pipe as defined in claim 1, wherein the grooves are U-shaped in section.
Claim 9
Dependent Claim
24 words
A heat transfer pipe as defined in claim 7, wherein the ratio between the depth and the width of groove is 0.4 at minimum.
Claim 10
Dependent Claim
24 words
A heat transfer pipe as defined in claim 7, wherein the ratio between the depth and the width of groove is 4.0 at maximum.
Claim 11
Dependent Claim
121 words
A heat transfer pipe adapted for use in a heat exchanger of an air conditioner, freezer, air separator, etc., which heat transfer pipe has an inner diameter in the range between 5 and 20 millimeters and is adapted to permit a boiling liquid or a condensing liquid to flow therethrough, said heat transfer pipe being formed on its inner wall surface with grooves having a depth from the wall surface to their bottoms in the range between 0.02 and 0.2 millimeters, a pitch between the adjacent grooves in the range between 0.1 and 0.5 millimeters, and an angle of inclination with respect to the axis of the heat transfer pipe in the range between 4° and 15° or 165° and 176°.
Claim 12
Dependent Claim
121 words
A heat transfer pipe adapted for use in a heat exchanger of an air conditioner, freezer, air separator, etc., which heat transfer pipe has an inner diameter in the range between 5 and 20 millimeters and is adapted to permit a boiling liquid or a condensing liquid to flow therethrough, said heat transfer pipe being formed on its inner wall surface with grooves having a depth from the wall surface to their bottoms in the range between 0.02 and 0.2 millimeters, a pitch between the adjacent grooves in the range between 0.1 and 0.5 millimeters, and an angle of inclination with respect to the axis of the heat transfer pipe in the range between 4° and 15° or 165° and 176°.
Claim 13
Dependent Claim
29 words
A heat transfer pipe as claimed in claim 9, wherein the angle of inclination of said grooves with respect to the axis of the heat transfer pipe is 7°.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-29 | 1981-02-28 | 1981-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-29 | 1985-02-28 | 1985-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-29 | 1989-02-28 | 1989-08-30 | $7700.00 | Window Closed / Lapsed |