U.S. patent application number 10/737083 was filed with the patent office on 2005-06-16 for internally enhanced tube with smaller groove top.
Invention is credited to Bennett, Donald L., Rottmann, Edward G., Tang, Liangyou.
Application Number | 20050126757 10/737083 |
Document ID | / |
Family ID | 34523140 |
Filed Date | 2005-06-16 |
United States Patent
Application |
20050126757 |
Kind Code |
A1 |
Bennett, Donald L. ; et
al. |
June 16, 2005 |
Internally enhanced tube with smaller groove top
Abstract
An internally enhanced heat pipe with a groove opening size that
is smaller than the size of the groove bottom.
Inventors: |
Bennett, Donald L.;
(Franklin, KY) ; Tang, Liangyou; (Hendersonville,
TN) ; Rottmann, Edward G.; (Bowling Green,
KY) |
Correspondence
Address: |
HODGSON RUSS LLP
ONE M & T PLAZA
SUITE 2000
BUFFALO
NY
14203-2391
US
|
Family ID: |
34523140 |
Appl. No.: |
10/737083 |
Filed: |
December 16, 2003 |
Current U.S.
Class: |
165/104.11 |
Current CPC
Class: |
F28F 1/40 20130101; F28D
15/046 20130101 |
Class at
Publication: |
165/104.11 |
International
Class: |
F28D 015/00 |
Claims
What is claimed is:
1. A heat pipe, comprising: a tubular member having an inner
surface defining an inner diameter and having a longitudinal axis;
a plurality of fins having side walls and a top wall, the fins
disposed on the inner surface of the tubular member, the fins
disposed so as to define a groove between adjacent fins, the groove
having an opening at the top and a groove bottom along the inner
surface, the groove having sides defined by the side walls of the
fins; and, wherein the width of the groove at its widest portion is
greater than the width of the groove opening.
2. The heat pipe of claim 1, wherein the cross-sectional area of
the groove is greater than the cross-sectional area of the
fins.
3. The heat pipe of claim 1, wherein the fins have a trapezoidal
shape.
4. The heat pipe of claim 1, wherein the fins are T-shaped.
5. The heat pipe of claim 1, wherein the fins are mushroom
shaped.
6. The heat pipe of claim 1, wherein the fins are Y-shaped.
7. The heat pipe of claim 1, wherein the fins are angled toward
each other to form a triangular shaped groove.
8. The heat pipe of claim 1, wherein the groove bottom is
curved.
9. The heat pipe of claim 1, wherein the groove bottom is
round.
10. The heat pipe of claim 1, wherein the groove height is 0.05 mm
to 5 mm.
11. The heat pipe of claim 1, where the width of the groove opening
is 0.05 mm to 5 mm.
12. The heat pipe of claim 1, where the groove pitch is 0.10 mm to
5 mm.
13. The heat pipe of claim 1, wherein the ratio of groove
cross-sectional area to groove height is 0.02 mm to 1 mm.
14. The heat pipe of claim 1, wherein the ratio of groove
cross-sectional/area to groove wall length is 0.01 mm to 1 mm.
15. The heat pipe of claim 1, wherein the ratio of the groove
opening to the largest width of the groove is 0.01 to 0.99.
16. The heat pipe of claim 1, wherein the height of the groove is
greater than the width of the groove.
17. The heat pipe of claim 1, wherein the width of the groove at
the groove bottom is greater than the width of the groove opening.
Description
FIELD OF INVENTION
[0001] The present invention relates to internally enhanced tubes
for improved heat transfer and specifically to a heat transfer tube
with inner grooves having a groove top opening that is smaller than
the largest opening in the groove.
BACKGROUND OF THE INVENTION
[0002] Heat pipes are typically used in heat exchangers for air
conditioning and refrigeration and for thermal management of
electronics devices such as computer CPU's. A heat pipe is a tube
which is sealed at both ends and provided with a limited quantity
of refrigerant. One end of the tube is exposed to a heat source,
where the liquid inside the tube is heated so that the liquid is
evaporated. The vapor flows to the opposite end of the tube which
is exposed to a heat sink. The vapor releases its heat to the heat
sink and condenses back to liquid form. The liquid will then flow
back to the end where the heat source is located to be evaporated.
These evaporation and condensation processes continue such that
heat is transferred from the heat source to the heat sink in a
continuous manner. The heat pipe described above has a much higher
heat transfer rate than solid heat conductors made of highly
conductive materials such as copper.
[0003] In order to draw liquid from the heat sink end back to the
heat source end, a wick structure is required, which has a
capillary effect. The capillary effect functions as a pump to move
liquid from the heat sink end to the heat source end. In current
heat pipes, the inner groove structure has been used as the wick of
a heat pipe. However, the current inner groove structures expose
the liquid flow to the vapor flow in the center of the heat pipe
and in the opposite flow direction to the liquid flow. The vapor
flow entrains liquid droplets and carries these droplets away from
the liquid stream. This entrainment of the liquid droplets into the
vapor flow has a detrimental effect on the performance of the heat
pipe.
[0004] The current designs have an inner groove wick structure with
a trapezoidal groove shape with the groove top being larger than
the groove bottom. This structure enhances the entrainment effect
discussed above so that the resulting heat pipe is less efficient
with regard to heat transfer. Accordingly, there is a need for a
heat pipe design that provides increased heat transfer performance
by reducing the entrainment effect described above.
SUMMARY OF THE INVENTION
[0005] The present invention meets the above-described need by
providing an internally enhanced tube with a groove opening size
that is smaller than the size of the largest opening in the
groove.
[0006] The present invention reduces the entrainment effect
described above by shielding the liquid flow from the vapor flow.
Due to the narrower groove opening at the top, the vapor flow in
the center of the tube is partially separated from the liquid flow
inside the groove. Accordingly, the liquid droplets are more
difficult to be carried away by the vapor flow traveling in the
opposite direction. Due to this shielding effect, the entrainment
effect is reduced so that more liquid can reach the heat source end
of the heat pipe and therefore the total heat transfer can be
increased.
[0007] In a first embodiment, the groove geometry is defined by a
plurality of trapezoidal-shaped fins.
[0008] In a second embodiment, the groove geometry is defined by a
plurality of T-shaped fins.
[0009] In a third embodiment, the groove geometry is defined by a
plurality of mushroom-shaped fins.
[0010] Common characteristics of the embodiments include, but are
not limited to, the following aspects. The groove opening is
smaller than the groove bottom. The groove cross-sectional area is
equal to or larger than the cross-sectional area of the fins that
form the grooves. And the height of the grooves are equal or larger
than the width of the grooves.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention is illustrated in the drawings in which like
reference characters designate the same or similar parts throughout
the figures of which:
[0012] FIG. 1 is a side elevation view of a first embodiment of the
present invention;
[0013] FIG. 2 is a side elevation view of a second embodiment of
the present invention;
[0014] FIG. 3 is a side elevation view of a third embodiment of the
present invention;
[0015] FIG. 4 is a side elevational view of a fourth embodiment of
the present invention;
[0016] FIG. 5 is a side elevational view of a fifth embodiment of
the present invention; and,
[0017] FIG. 6 is a side elevational view of a sixth embodiment of
the present invention.
DETAILED DESCRIPTION
[0018] In FIG. 1, a section 10 of heat pipe 13 is shown. The pipe
13 may be constructed of copper, copper alloy, or other heat
conductive materials. The pipe 13 is shown in a partial view that
does not show the overall profile of the pipe. As will be evident
to those of ordinary skill in the art, the enhancement of the
present invention may be provided for pipe having many
cross-sectional shapes including, but not limited to, round, oval,
square, rectangular, etc. The longitudinal axis of the pipe 13 is
oriented normal to the page. The heat pipe 13 has an outer wall 16
and an internally enhanced inner wall 19. The heat pipe 13 has a
wall thickness 22 measured from the bottom surface 24 of the groove
25 to the outer wall 16. The groove 25 has an opening 29 at the top
with respect to the orientation of FIG. 1. As shown, grooves 25 are
formed by trapezoidal shaped fins 26 that result in grooves 25
having bottom surface 24 and opposed angled walls 31 and 34. The
walls 31 and 34 angle inward toward each other. As a result, the
width 39 at the bottom of the groove 25 is larger than the width 42
of opening 29 at the top of groove 25. By reversing the groove
opening size to be smaller than the groove bottom, the liquid flow
from the heat sink end to the heat source end is better shielded
from the vapor flow. The cross-sectional area of the groove 25 is
equal to or larger than the cross-sectional area of the fins 26
that form the grooves 25. Also, the height 70 of the grooves 25 is
equal to or larger than the width 39 of the grooves 25. As a result
of the shielding effect of the groove shape, the entrainment of
liquid into the vapor stream is reduced so that more liquid can
reach the heat source end of the heat pipe, and the total heat
transferred can be increased.
[0019] The heat pipe 13 of the present invention also has the
following properties. The groove height 70 is between 0.05 mm to 5
mm. The groove opening 29 is 0.05 mm to 5 mm in length, and the
groove pitch is 0.10 to 5 mm. The ratio of groove cross-sectional
area to groove height is 0.02 mm to 1 mm. The ratio of groove
cross-sectional area to groove wall length is 0.01 mm to 1 mm. And
the ratio of groove opening to the largest width of the groove is
0.01 to 0.99.
[0020] Turning to FIG. 2, an alternate embodiment for a heat pipe
99 of the present invention includes a set of grooves 100 formed
between T-shaped fins 103. The heat pipe 99 has an outer surface
106. The longitudinal axis of the pipe is oriented normal to the
page with respect to FIG. 2. The pipe 99 has a wall thickness 109
measured between the bottom surface 112 of the groove 100 and the
outer surface 106. The groove 100 is formed in part by opposed
walls 115, 118. The outer end 113 of the T-shaped fins 103 defines
an opening 121. The opening 121 has a width 124. The width 124 is
smaller than the width 127 along the bottom surface 112. The
cross-sectional area of the groove 100 is equal to or larger than
the cross-sectional area of the fins 103. Also, the height 150 of
the groove 100 is equal to or larger than the width 127.
[0021] In FIG. 3, another alternate embodiment of the present
invention is shown. Heat pipe 200 has a plurality of fins 203
having a mushroom-shaped profile. A plurality of grooves 201 are
formed between the fins 203. Heat pipe 200 has an outer surface
206. The longitudinal axis of the pipe is oriented normal to the
page with respect to FIG. 2. The pipe 200 has a wall thickness 209
measured between the bottom surface 212 of the groove 201 and the
outer surface 206. The groove 201 is formed in part by opposed
walls 215, 218. The ends 213 of adjacent fins 203 define an opening
221. The opening 221 has a width 224 that is smaller than the width
227 along bottom surface 212. The cross-sectional area of the
groove 201 is equal to or larger than the cross-sectional area of
the fins 203. Also, the height 250 of the groove 201 is equal to or
larger than the width 127.
[0022] Turning to FIG. 4, another embodiment of the present
invention is shown. Heat pipe 300 has a plurality of fins 303
forming grooves 306 between adjacent fins 303. As shown, the bottom
of groove 306 is round. Other shapes for the bottom wall may also
be suitable including flat and other non-round shapes.
[0023] The longitudinal axis of the pipe is oriented perpendicular
to the page. The opening 309 at the top of the groove 306 is
smaller than the largest width 312 of the groove 306. The largest
width 312 is located in a midportion of groove 306.
[0024] In FIG. 5, angled fins 400 provide triangular shaped grooves
403. The top of the grooves 403 have an opening 406 with a width
409 that is smaller than the largest width of the grooves 403. The
largest width for the groove 403 is located at the bottom wall
412.
[0025] In FIG. 6, Y-shaped fins 500 provide grooves 503 located
therebetween. The width of the opening 506 at the top of the groove
503 is smaller than the widest opening 512 of the groove 503.
[0026] While the invention has been described in connection with
certain embodiments, it is not intended to limit the scope of the
invention to the particular forms set forth, but, on the contrary,
it is intended to cover such alternatives, modifications, and
equivalents as may be included within the spirit and scope of the
invention as defined by the appended claims.
* * * * *