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US4040479A Expired / Lapsed US ⏱️ 0.0 years remaining

Finned tubing having enhanced nucleate boiling surface

Assignee: Bank of Nova Scotia
•
Filing: 1975-09-03
•
Granted: 1977-08-09
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Expires: 1995-09-03
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Abstract

Abstract An improved nucleate boiling surface can be obtained on a finned metal heat transfer tube by providing very narrow transverse gaps in its fins. The narrow gaps can be attained by knurling or otherwise deforming a smooth surfaced tube member to notch and partially work harden its surface and then subjecting the knurled portion to a finning operation. The resulting tube has fissure like gaps having a tapered width in the range of 0-0.006 inches in the tip area of the fins which become nucleation sites for boiling enhancement. In a metal working apparatus, by mounting the knurling rolls on the same arbors as the finning disks, a tube can be progressively knurled and then finned in a single pass through the apparatus. If desired, the tube can also be internally ridged as it is being externally finned.

Inventors

  • 👤 Bonnie J. Campbell
  • 👤 Klaus R. Rieger

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-24 09:47
CPC Classifications
F; F28; F28F; F28F13/00; F28F13/18; F28F13/185; F28F13/187

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 64 words
A heat exchanger tube comprising a tube wall having integral, radially extending fins formed in its outer surface, the tips of the fins including a plurality of fissure like transverse gaps around their peripheries, at least the majority of said gaps having a depth less than the height of the fin and a tapered width in the range from 0 to about 0.006 inches.
Claim 2
Dependent Claim 64 words
A heat exchanger tube comprising a tube wall having integral, radially extending fins formed in its outer surface, the tips of the fins including a plurality of fissure like transverse gaps around their peripheries, at least the majority of said gaps having a depth less than the height of the fin and a tapered width in the range from 0 to about 0.006 inches.
Claim 3
Dependent Claim 31 words
The heat exchange tube of claim 1 wherein the side surfaces of said fins are substantially smooth and free of outward projections at the base portions of said fissure like gaps.
Claim 4
Dependent Claim 23 words
The heat exchanger tube of claim 1 wherein said tube has between 26 and 35 fins per inch formed in its outer surface.
Claim 5
Dependent Claim 23 words
The heat exchanger tube of claim 1 wherein said tube has between 11 and 50 fins per inch formed in its outer surface.
Claim 6
Dependent Claim 28 words
The heat exchange tube of claim 4 wherein said tube has between 10 and 80 fissure like gaps per inch formed in the tip edges of its fins.
Claim 7
Dependent Claim 28 words
The heat exchange tube of claim 4 wherein said tube has between 20 and 70 fissure like gaps per inch formed in the tip edges of its fins.
Claim 8
Dependent Claim 28 words
The heat exchange tube of claim 6 wherein said fissure like gaps extend less than about 25% of the distance between the fin tips and the fin roots.
Claim 9
Dependent Claim 22 words
The heat exchange tube of claim 7 wherein said fissure like gaps are at an angle to the axis of the tube.
Claim 10
Dependent Claim 43 words
The heat exchange tube of claim 8 wherein about half the fissure like gaps are at a first positive angle to a line parallel to the axis of the tube and the other half are at a second negative angle to said line.
Claim 11
Dependent Claim 21 words
The heat exchange tube of claim 9 wherein said first and second angles are equal in magnitude and are about 30°.

References Cited (Backward Citations)

US3326283A Cited
US3566514A Cited
US3454081A Cited
US3789915A Cited
US3906604A Cited
US3893322A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1980-08-08 1981-02-07 1981-08-09 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1984-08-08 1985-02-07 1985-08-09 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1988-08-08 1989-02-07 1989-08-09 $7700.00 Window Closed / Lapsed

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