Patent US3847212A successfully refreshed from Google Patents.
US3847212A
Expired / Lapsed
US
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Heat transfer tube having multiple internal ridges
Assignee: Bank of Nova Scotia
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Filing: 1973-07-05
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Granted: 1974-11-12
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Expires: 1993-07-05
Abstract
Abstract Improved externally finned metal heat transfer tube has multiple-start helical ridging on its inner surface which conforms to a range of values of a disclosed equation relating the size and shape of the ridging to its pitch and to the inner diameter of the tube. The inside tube wall profile, in axial section, is defined by a straight line interrupted by the internal ridges. The ridge tips are connected to the straight line segments of the profile by convex and concave portions which meet at a point of common tangency. The improved tube provides especially good results in systems, such as submerged-tube, refrigerated coolers, wherein the film resistance of the intube fluid would represent a substantial portion of the total thermal resistance if the improved internal surface were not provided. A method of designing a tube for a particular coefficient of internal heat transfer is also disclosed.
Inventors
- 👤 J Withers
- 👤 K Rieger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:26
CPC Classifications
F; F28; F28F; F28F1/00; F28F1/10; F28F1/42; F28F1/422; Y; Y10; Y10S; Y10S165/00; Y10S165/51; Y10S165/515; Y10T; Y10T29/00; Y10T29/49; Y10T29/4935; Y10T29/49377; Y10T29/49378; Y10T29/49382; Y10T29/49384
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
224 words
A metal tube having an improved heat transfer rate to or from an internally flowing fluid, characterized in that said tube has at least one integral external helical fin of a predetermined pitch distance and lead angle and a plurality of integral multiple start internal helical ridges extending radially inwardly from the inner wall of the tube, said plurality of internal helical ridges having a lead angle of less than 60* (as measured from a perpendicular to the tube axis) and a pitch distance which is greater than the pitch distance of said at least one external fin but wherein the respective lead angles of said at least one external fin and said plurality of internal ridges are different from each other in magnitude and/or sense, said inner wall of said tube being so shaped as to define, in a longitudinal sectioned profile, an intermediate flat portion between adjacent internal ridges, with said ridges having a ridge cross-sectional profile which includes a pair of side boundaries connecting the flat inner wall portions of the tube intermediate adjacent pairs of ridges and the tips of the ridges, said side boundaries being comprised of concave and convex portions which connect at a point of inflection radially outward from the tip and at a distance from the tip which is less than the height of the ridge.
Claim 2
Dependent Claim
224 words
A metal tube having an improved heat transfer rate to or from an internally flowing fluid, characterized in that said tube has at least one integral external helical fin of a predetermined pitch distance and lead angle and a plurality of integral multiple start internal helical ridges extending radially inwardly from the inner wall of the tube, said plurality of internal helical ridges having a lead angle of less than 60* (as measured from a perpendicular to the tube axis) and a pitch distance which is greater than the pitch distance of said at least one external fin but wherein the respective lead angles of said at least one external fin and said plurality of internal ridges are different from each other in magnitude and/or sense, said inner wall of said tube being so shaped as to define, in a longitudinal sectioned profile, an intermediate flat portion between adjacent internal ridges, with said ridges having a ridge cross-sectional profile which includes a pair of side boundaries connecting the flat inner wall portions of the tube intermediate adjacent pairs of ridges and the tips of the ridges, said side boundaries being comprised of concave and convex portions which connect at a point of inflection radially outward from the tip and at a distance from the tip which is less than the height of the ridge.
Claim 3
Dependent Claim
87 words
A metal tube in accordance with claim 1 wherein the ratio of the width, b, of a ridge, as measured in an axial direction, to it pitch, p, is between 0.10 and 0.20; the ratio of the height, e, of a ridge to the height from its tip to the point of inflection, y, is between 1.50 and 5.0; and the value of a severity factor, phi , is less than 0.0025, where phi e2/pdi, and where di is the maximum projected internal diameter of the tube.
Claim 4
Dependent Claim
77 words
A metal tube in accordance with claim 2 characterized in that the inside heat transfer coefficient constant, Ci, is approximately equal to 0.0264 + (22.1)( phi )(1-b/p)(e/y)1/3, and wherein: phi is within the range 0.00057 - 0.0025; e is within the range 0.0125 - 0.075; p is within the range 0.25 - 0.70; di is within the range 0.20 - 3.00; b is within the range 0.02 -0.15; and, y is within the range 0.0065 - 0.05.
Claim 5
Dependent Claim
194 words
A metal tube having an improved heat transfer rate to or from an internally flowing fluid, characterized in that said tube has annular integral external fins of a predetermined pitch distance and a plurality of integral multiple start internal helical ridges extending radially inwardly from the inner wall of the tube, said plurality of internal helical ridges having a pitch distance which is greater than the pitch distance of said external fins but wherein the lead angle of said plurality of internal ridges is less than 60* (as measured from a perpendicular to the tube axis), said inner wall of said tube being so shaped as to define, in a longitudinal sectioned profile, an intermediate flat portion between adjacent internal ridges, with said ridges having a ridge cross-sectional profile which includes a pair of side boundaries connecting the flat inner wall portions of the tube intermediate adjacent pairs of ridges and the tips of the ridges, said side boundaries being comprised of concave and convex portions which connect at a point of inflection radially outward from the tip and at a distance from the tip which is less than the height of the ridge.
Claim 6
Dependent Claim
194 words
A metal tube having an improved heat transfer rate to or from an internally flowing fluid, characterized in that said tube has annular integral external fins of a predetermined pitch distance and a plurality of integral multiple start internal helical ridges extending radially inwardly from the inner wall of the tube, said plurality of internal helical ridges having a pitch distance which is greater than the pitch distance of said external fins but wherein the lead angle of said plurality of internal ridges is less than 60* (as measured from a perpendicular to the tube axis), said inner wall of said tube being so shaped as to define, in a longitudinal sectioned profile, an intermediate flat portion between adjacent internal ridges, with said ridges having a ridge cross-sectional profile which includes a pair of side boundaries connecting the flat inner wall portions of the tube intermediate adjacent pairs of ridges and the tips of the ridges, said side boundaries being comprised of concave and convex portions which connect at a point of inflection radially outward from the tip and at a distance from the tip which is less than the height of the ridge.
Claim 7
Dependent Claim
199 words
A metal tube having an improved heat transfer rate to Or from an internally flowing fluid, characterized in that said tube has a plurality of integral radial external fins and a plurality of integral multiple start internal helical ridges extending radially inwardly from the inner wall of the tube, and wherein the lead angle of said plurality of internal ridges is less than 60*, as measured from a perpendicular to the tube axis, but wherein the respective lead angle of said plurality of radial external fins and said plurality of internal ridges are different from each other in magnitude and/or sense, said inner wall of said tube being so shaped as to define, in a longitudinal sectioned profile, an intermediate flat portion between adjacent internal ridges, with said ridges having a ridge cross-sectional profile which includes a pair of said boundaries connecting the flat inner wall portions of the tube intermediate adjacent pairs of ridges and the tips of the ridges, said side boundaries being comprised of concave and convex portions which connect at a point of inflection radially outward from the tip and at a distance from the tip which is less than the height of the ridge.
Claim 8
Dependent Claim
199 words
A metal tube having an improved heat transfer rate to Or from an internally flowing fluid, characterized in that said tube has a plurality of integral radial external fins and a plurality of integral multiple start internal helical ridges extending radially inwardly from the inner wall of the tube, and wherein the lead angle of said plurality of internal ridges is less than 60*, as measured from a perpendicular to the tube axis, but wherein the respective lead angle of said plurality of radial external fins and said plurality of internal ridges are different from each other in magnitude and/or sense, said inner wall of said tube being so shaped as to define, in a longitudinal sectioned profile, an intermediate flat portion between adjacent internal ridges, with said ridges having a ridge cross-sectional profile which includes a pair of said boundaries connecting the flat inner wall portions of the tube intermediate adjacent pairs of ridges and the tips of the ridges, said side boundaries being comprised of concave and convex portions which connect at a point of inflection radially outward from the tip and at a distance from the tip which is less than the height of the ridge.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-11 | 1978-05-13 | 1978-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-11 | 1982-05-13 | 1982-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-11 | 1986-05-13 | 1986-11-12 | $7700.00 | Window Closed / Lapsed |