U.S. patent application number 09/899101 was filed with the patent office on 2002-01-31 for refrigerant tube for heat exchangers.
Invention is credited to Jang, Dong Yeon, Lee, Wook Yong, Oh, Sai Kee, Oh, Se Yoo.
Application Number | 20020011332 09/899101 |
Document ID | / |
Family ID | 19676520 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020011332 |
Kind Code |
A1 |
Oh, Sai Kee ; et
al. |
January 31, 2002 |
Refrigerant tube for heat exchangers
Abstract
A refrigerant tube for heat exchangers is disclosed. The
refrigerant tube has an outer diameter of not larger than 5.3 mm,
with a plurality of internal spiral fins formed on the inner
surface of the refrigerant tube. The refrigerant tube has a
thickness of 0.16 mm.about.0.2 mm. The internal spiral fins are set
in their number to 40.about.50, and each have a height of 0.15
mm.about.0.18 mm, a projection angle of
38.degree..about.42.degree., and a spiral angle of
6.degree..about.20.degree.. Due to the internal spiral fins in
addition to the reduced outer diameter of the refrigerant tube, the
tube reduces the production cost of heat exchangers and
accomplishes the recent trend of compactness of the heat
exchangers. The tube also has several advantages expected from
small-diameter refrigerant tubes, such as a reduction in air-side
pressure loss, and improves heat transfer efficiency of the heat
exchangers. This refrigerant tube thus enhances the heat exchange
operational performance of the heat exchangers.
Inventors: |
Oh, Sai Kee; (Seoul, KR)
; Jang, Dong Yeon; (Kyungki-do, KR) ; Oh, Se
Yoo; (Seoul, KR) ; Lee, Wook Yong;
(Kwangmyung-si, KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
19676520 |
Appl. No.: |
09/899101 |
Filed: |
July 6, 2001 |
Current U.S.
Class: |
165/184 ;
165/133; 165/179 |
Current CPC
Class: |
F28F 1/40 20130101 |
Class at
Publication: |
165/184 ;
165/133; 165/179 |
International
Class: |
F28F 013/18; F28F
019/02; F28F 001/42; F28F 001/36 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 6, 2000 |
KR |
2000-38501 |
Claims
What is claimed is:
1. A refrigerant tube assembled with a plurality of air guide fins
in a heat exchanger, wherein said refrigerant tube has an outer
diameter of not larger than 5.3 mm, with a plurality of internal
spiral fins formed on an inner surface of said refrigerant
tube.
2. The refrigerant tube according to claim 1, wherein a thickness
of said refrigerant tube is set to 0.16 mm.about.0.2 mm.
3. The refrigerant tube according to claim 1, wherein said internal
spiral fins are set in their number to 40.about.50, and each have a
height of 0.15 mm.about.0.18 mm, a projection angle of
38.degree..about.42.degree., and a spiral angle of
6.degree..about.20.degree..
4. The refrigerant tube according to claim 3, wherein said spiral
angle of the internal spiral fins is set to
6.degree..about.10.degree..
5. The refrigerant tube according to claim 3, wherein said spiral
angle of the internal spiral fins is set to
16.degree..about.20.degree..
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a refrigerant tube for heat
exchangers and, more particularly, to a refrigerant tube for heat
exchangers of air conditioning systems, provided with a plurality
of internal spiral fins on its inner surface for improving its heat
exchange effect.
[0003] 2. Description of the Prior Art
[0004] FIG. 1 is a perspective view of a conventional heat
exchanger for air conditioning systems. As shown in the drawing,
the conventional heat exchanger comprises a refrigerant tube 11 and
a plurality of air guide fins 3. The refrigerant tube 11 is
regularly bent to form a zigzag-shaped tube assembly. This tube 11
forms a refrigerant passage of the heat exchanger. The air guide
fins 3 are vertically arranged at regular intervals, with the
linear parts of the zigzagged refrigerant tube 11 passing through
the fins 3. During an operation of the heat exchanger, refrigerant
flowing in the refrigerant tube 11 absorbs or dissipates heat from
or to air currents flowing around the tube 11.
[0005] As shown in FIGS. 2 and 3, the conventional refrigerant tube
11 for such heat exchangers has an outer diameter of 7 mm or 9 mm,
with a plurality of internal spiral fins 13 regularly formed on the
inner surface of the tube 11 while defining a plurality of grooves
15 between them. The internal fins 13 and grooves 15 enlarge the
heat transferring surface area of the tube 11, in addition to
agitating the thermal boundary layer inside the refrigerant flowing
in the tube 11. Therefore, the fins 13 and grooves 15 promote heat
transfer between the refrigerant inside the tube 11 and air
currents outside the tube 11, thus improving the heat exchange
effect of the heat exchanger.
[0006] In a detailed description, the fins 13 and grooves 15
enlarge the internal surface area of the tube 11, at which the tube
11 comes into contact with liquid or gas refrigerant. The fins 13
and grooves 15 also produce capillary effect and shear flow in
refrigerant flowing in the tube 11 at a low flow rate, thus
increasing the turbulent intensity of the liquid layer in the tube
11. In such a case, the internal surface area of the tube 11, and
the turbulent intensity and thickness of the liquid layer in the
tube 11 vary in accordance with the number and shape of the fins
13.
[0007] While designing such refrigerant tubes 11 for heat
exchangers, it is necessary to predetermine the optimal design
factors of the internal fins 13, such as the number, height,
projecting angle and spiral angle of the fins 13.
[0008] In the prior art, a standard method of predetermining the
design factors of such internal fins of refrigerant tubes has not
been proposed, but the internal fins have been designed in
accordance with an optimal combination of design factors obtained
from repeated tests.
[0009] That is, the tests are performed while changing the design
factors of the internal fins under a variety of expected
conditions, such as the quantity and kind of refrigerant and
environmental conditions, so as to produce an optimal combination
of the design factors.
[0010] The conventional refrigerant tube 11 for heat exchangers
designed through the above-mentioned process has an outer diameter
of 7 mm or 9 mm and a thickness (t.sub.1) of 0.27 mm, with sixty
internal fins 13 each having a height (H.sub.1) of 0.15 mm, a
projection angle (.beta..sub.1) of 56.degree., and a spiral angle
(.alpha..sub.1) of 18.degree..
[0011] In recent years, it is desired to reduce the outer diameter
of the refrigerant tube 11 in an effort to reduce the production
cost and air-side pressure loss of the tube 11.
[0012] When the above-mentioned design factors of the fins 13 are
applied to a refrigerant tube 11, having such a reduced outer
diameter, without changing the design factors of the fins 13, the
refrigerant-side pressure loss of the tube 11 is undesirably
increased, thus reducing the heat exchange efficiency of the tube
11. In addition, the above-mentioned design factors of the internal
fins 13 exceed design limits of fins that can be practically formed
on the tube 11 having such a reduced outer diameter, and so it is
almost impossible to produce a desired refrigerant tube, having
such a reduced outer diameter and provided with fins 13 having such
design factors.
[0013] The conventional refrigerant tube 11 is designed without
considering the use of newly proposed alternative refrigerant in
place of typical refrigerant, and so the tube 11 used with such
alternative refrigerant cannot perform its designed operational
function due to pressure loss and heat transfer coefficient of the
alternative refrigerant which are different from those of the
typical refrigerant.
[0014] Therefore, it is necessary to propose a refrigerant tube,
which has a reduced outer diameter and internal fins having
optimally designed number and shape, thus reducing the pressure
loss of refrigerant and improving the heat transfer characteristics
of the refrigerant, such as heat transfer coefficient.
SUMMARY OF THE INVENTION
[0015] Accordingly, the present invention has been made keeping in
mind the above problems occurring in the prior art, and an object
of the present invention is to provide a refrigerant tube for heat
exchangers, which has a desirably reduced outer diameter, in
addition to internal fins having optimal design factors preferably
compatible with the reduced outer diameter of the tube, and which
thus reduces the production cost of the heat exchangers and
accomplishes the recent trend of compactness of the heat
exchangers, and which has several advantages expected from
small-diameter refrigerant tubes, such as a reduction in air-side
pressure loss, and which improves heat transfer efficiency of the
heat exchangers, and enhances the heat exchange operational
performance of the heat exchangers.
[0016] In order to accomplish the above object, the present
invention provides a refrigerant tube assembled with a plurality of
air guide fins in a heat exchanger, wherein the refrigerant tube
has an outer diameter of not larger than 5.3 mm, with a plurality
of internal spiral fins formed on the inner surface of the
refrigerant tube.
[0017] The refrigerant tube has a thickness of 0.16 mm.about.0.2
mm.
[0018] In addition, the internal spiral fins are set in their
number to 40.about.50, and each have a height of 0.15 mm.about.0.18
mm, a projection angle of 38.degree..about.42.degree., and a spiral
angle of 6.degree..about.20.degree..
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The above and other objects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0020] FIG. 1 is a perspective view of a conventional heat
exchanger;
[0021] FIG. 2 is a broken view of a conventional refrigerant tube
for heat exchangers, showing the interior of the tube;
[0022] FIG. 3 is a sectional view of a part of the conventional
refrigerant tube for heat exchangers;
[0023] FIG. 4 is a broken view of a refrigerant tube for heat
exchangers in accordance with the preferred embodiment of the
present invention, showing the interior of the tube; and
[0024] FIG. 5 is a sectional view of a part of the refrigerant tube
of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Reference now should be made to the drawings, in which the
same reference numerals are used throughout the different drawings
to designate the same or similar components.
[0026] FIG. 4 is a broken view of a refrigerant tube for heat
exchangers in accordance with the preferred embodiment of the
present invention, showing the interior of the tube. FIG. 5 is a
sectional view of a part of the refrigerant tube.
[0027] As shown in the drawings, the refrigerant tube 51 according
to the present invention is used in a heat exchanger for air
conditioning systems, which consists of a plurality of air guide
fins (not shown) vertically arranged at regular intervals, with the
linear parts of the refrigerant tube 51 passing through the air
guide fins. The refrigerant tube 51 of this invention has an outer
diameter of not larger than 5.3 mm, with a plurality of internal
spiral fins 53 formed on the inner surface of the tube 51 while
defining a plurality of grooves 55 between them.
[0028] The tube 51 has a thickness (t) of 0.16 mm.about.0.2 mm,
while the number of the internal fins 53 is set to 40.about.50. In
addition, the internal fins 53 each have a spiral angle (.alpha.)
of 6.degree..about.20.degree., a height (H) of 0.15 mm.about.0.18
mm, and a projection angle (.beta.) of 38.degree.42.degree..
[0029] In the present invention, the spiral angle (.alpha.) of the
internal fins 53 is preferably set to 6.degree..about.10.degree. or
16.degree..about.20.degree..
[0030] In comparison with a heat exchanger using a conventional
refrigerant tube 11 having an outer diameter of 7 mm or 9 mm, a
heat exchanger using the refrigerant tube 51 of this invention
having a reduced outer diameter of 5.3 mm is increased in its
refrigerant-side pressure loss at the same flow rate of
refrigerant, but is reduced in the thickness (t) of its refrigerant
tube 51. The internal fins 53 of the tube 51 according to this
invention are designed such that they are optimally compatible with
the reduced outer diameter of the tube 51, while considering both
the increased refrigerant-side pressure loss and the reduced tube
thickness (t). It is noted that the refrigerant-side pressure loss
of the refrigerant tube 51 according to this invention is
preferably reduced to improve the heat exchange operational
performance of the heat exchanger. In addition, it is possible for
manufacturers of such heat exchangers to easily manage the
allowance of the internal fins 53 during a process of producing the
refrigerant tubes 51.
[0031] In addition, the refrigerant tube 51 having the internal
fins 53 of this invention can easily use alternative refrigerant in
place of typical refrigerant without changing the dimension of the
tube 51 or the internal fins 53 since the fins 53 are designed in
consideration of a change in the pressure loss and heat transfer
coefficient in the case of replacing typical refrigerant with
alternative refrigerant.
[0032] As described above, the present invention provides a
refrigerant tube for heat exchangers. The tube of this invention
has a desirably reduced outer diameter, in addition to internal
fins having optimal design factors preferably compatible with the
reduced outer diameter of the tube. This tube thus reduces the
production cost of heat exchangers and accomplishes the recent
trend of compactness of the heat exchangers, in addition to having
several advantages expected from small-diameter refrigerant tubes,
such as a reduction in air-side pressure loss. The refrigerant tube
of this invention also improves heat transfer efficiency of the
heat exchangers, and enhances the heat exchange operational
performance of the heat exchangers.
[0033] In addition, since the internal fins of this invention are
designed such that they are compatible with a small-diameter
refrigerant tube, the tube optimally reduces refrigerant-side
pressure loss. It is also possible for manufacturers of the heat
exchangers for air conditioning systems to easily manage the
allowance of the internal fins during a process of producing the
refrigerant tubes.
[0034] Although a preferred embodiment of the present invention has
been described for illustrative purposes, those skilled in the art
will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
* * * * *