U.S. patent application number 09/313785 was filed with the patent office on 2001-06-14 for heat exchanger.
This patent application is currently assigned to Stephen G. Adrian. Invention is credited to ANDO, TOSHIAKI, AOYAGI, OSAMU, YOKOYAMA, SHOICHI.
Application Number | 20010003309 09/313785 |
Document ID | / |
Family ID | 26452521 |
Filed Date | 2001-06-14 |
United States Patent
Application |
20010003309 |
Kind Code |
A1 |
AOYAGI, OSAMU ; et
al. |
June 14, 2001 |
HEAT EXCHANGER
Abstract
In a heat exchanger of the present invention for exchanging heat
between fluid flowing in a flow passage in a heat exchanger tube
and fluid flowing outside of said heat exchanger tube, a solid
bar-like insertion member or a hollow bar-like insertion member
whose opposite ends are closed is provided in said flow passage in
which a fluid having phase change flows in gas-liquid two phase
state or liquid phase state, a cross section of said insertion
member is formed into a substantially circle shape, a polygonal
shape or a starlike shape, and a cross-sectional area of a flow
passage in which said fluid flows is reduced as a mass flow rate
quality of said fluid is reduced. With this construction, it is
possible to restrain the pressure loss at the time of evaporation,
and the evaporation ability can be enhanced or can be restrained
from being deteriorated.
Inventors: |
AOYAGI, OSAMU; (SHIGA,
JP) ; ANDO, TOSHIAKI; (SHIGA, JP) ; YOKOYAMA,
SHOICHI; (SHIGA, JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN, HATTORI,
MCLELAND & NAUGHTON, LLP
1725 K STREET, NW, SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
Stephen G. Adrian
|
Family ID: |
26452521 |
Appl. No.: |
09/313785 |
Filed: |
May 17, 1999 |
Current U.S.
Class: |
165/109.1 ;
165/146 |
Current CPC
Class: |
F28F 13/12 20130101;
F28D 1/0477 20130101; F28F 1/32 20130101; F28F 13/06 20130101 |
Class at
Publication: |
165/109.1 ;
165/146 |
International
Class: |
F28F 013/12 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 1998 |
DE |
10-134869 |
Apr 21, 1999 |
DE |
11-113577 |
Claims
What is claimed is:
1. A heat exchanger for exchanging heat between fluid flowing in a
flow passage in a heat exchanger tube and fluid flowing outside of
said heat exchanger tube, wherein a solid bar-like insertion member
or a hollow bar-like insertion member whose opposite ends are
closed is provided in said flow passage in which a fluid having
phase change flows in gas-liquid two phase state or liquid phase
state, a cross section of said insertion member is formed into a
substantially circle shape, a polygonal shape or a starlike shape,
and a cross-sectional area of a flow passage in which said fluid
flows is reduced as a mass flow rate quality of said fluid is
reduced.
2. A heat exchanger for exchanging heat between fluid flowing in a
flow passage in a heat exchanger tube and fluid flowing outside of
said heat exchanger tube, wherein a bar-like insertion member is
provided in said flow passage in which a fluid having phase change
flows in gas-liquid two phase state or liquid phase state, and a
cross-sectional area of a flow passage in which said fluid flows is
reduced as a mass flow rate quality of said fluid is reduced.
3. A heat exchanger according to claim 1 or 2, wherein a
cross-sectional area of said insertion member is discontinuously
varied.
4. A heat exchanger according to claim 1 or 2, wherein a
cross-sectional area of said insertion member is continuously
varied.
5. A heat exchanger for exchanging heat between fluid flowing in a
flow passage in a heat exchanger tube and fluid flowing outside of
said heat exchanger tube, wherein a solid bar-like insertion member
or a hollow bar-like insertion member whose opposite ends are
closed is provided in said flow passage in which a fluid having
phase change flows in gas-liquid two phase state or liquid phase
state, and a cross section of said insertion member is formed into
a substantially circle shape, a polygonal shape or a starlike
shape.
6. A heat exchanger according to any one of claims 1, 2 and 5,
wherein said insertion member is provided on its outer surface with
a groove, or a bump and a dip.
7. A heat exchanger according to any one of claims 1, 2 and 5,
wherein said insertion member is made of porous material.
8. A heat exchanger according to any one of claims 1, 2 and 5,
wherein said insertion member is provided in plural into
bundle.
9. A heat exchanger according to any one of claims 1, 2 and 5,
wherein a refrigerant comprising hydro fluorocarbon (HFC) or
hydrocarbon (HC) as main component is used as said fluid flowing in
said flow passage in said heat exchanger tube.
10. A heat exchanger according to claim 3, wherein said insertion
member is provided on its outer surface with a groove, or a bump
and a dip.
11. A heat exchanger according to claim 3, wherein said insertion
member is made of porous material.
12. A heat exchanger according to claim 3, wherein said insertion
member is provided in plural into bundle.
13. A heat exchanger according to claim 3, wherein a refrigerant
comprising hydro fluorocarbon (HFC) or hydrocarbon (HC) as main
component is used as said fluid flowing in said flow passage in
said heat exchanger tube.
14. A heat exchanger according to claim 4, wherein said insertion
member is provided on its outer surface with a groove, or a bump
and a dip.
15. A heat exchanger according to claim 4, wherein said insertion
member is made of porous material.
16. A heat exchanger according to claim 4, wherein said insertion
member is provided in plural into bundle.
17. A heat exchanger according to claim 4, wherein a refrigerant
comprising hydro fluorocarbon (HFC) or hydrocarbon (HC) as main
component is used as said fluid flowing in said flow passage in
said heat exchanger tube.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat exchanger such as a
heat exchanger having fins or a double tube heat exchanger mainly
used in an air conditioner.
BACKGROUND TECHNIQUE
[0002] As shown in FIG. 8, a conventional heat exchanger having
fins comprises fins 201 arranged at a predetermined distance from
one another, and heat exchanger tubes 202 inserted through fin
surfaces of the fins 201 perpendicularly to the latter. A current
203 of air flows in the direction of the arrow between the fins,
and exchanges heat with fluid flowing the passages of the heat
exchanger tubes 202. When such a heat exchanger having fins is
used, it is common that an end portion thereof is bent at a
predetermined radius of curvature R, and the heat exchanger is
accommodated in an outdoor unit of an air conditioner.
[0003] First prior art (Japanese Patent Application Laid-open No.
S61-15089) is shown in FIGS. 9a and 9b.
[0004] FIG. 9a is a vertical sectional view showing a portion of a
heat exchanger tube, and FIG. 9b is an enlarged sectional view of
an essential portion showing an inner wall surface of the heat
exchanger tube.
[0005] According to the first prior art of the heat exchanger, a
coil 204 comprising spirally wound metal fine wire is inserted into
a heat exchanger tube 202, an outer periphery of this coil 204 is
tightly fixed to an inner surface of the heat exchanger tube 202,
and a large number of powdery members 205 are jointed to the inner
surface of the heat exchanger tube 202 to form a porous material
layer.
[0006] According to this structure, heat transfer area of the inner
surface of the heat exchanger tube 202 is increased, a turbulent
flow effect, a capillary action effect and a nucleate boiling
effect are exhibited to enhance the heat transfer performance.
[0007] Second prior art (Japanese Utility Model Registration
Application Laid-open No. S58-52491) is shown in FIG. 10.
[0008] FIG. 10 is a sectional view of a heat exchanger having fins
taken along the surface passing through the center of a heat
exchanger tube thereof.
[0009] According to the second prior art, a spacer 206 which can be
deformed by heat is inserted into a heat exchanger tube 202, and
after the insertion, the spacer 206 is heated so that the spacer
206 is tightly adhered to an inner wall of the tube. A fin group
201 is jointed to an outer peripheral surface of the heat exchanger
tube 202.
[0010] With this structure, the heat transfer area of the inner
surface of the heat exchanger tube 202 is increased, and a
turbulent flow effect is exhibited to enhance the heat transfer
performance.
[0011] Third prior art (Japanese Patent Application No. H10-2638)
is shown in FIG. 11.
[0012] FIG. 11 is a perspective view showing a structure of a heat
exchanger having fins.
[0013] According to the third prior art, in the heat exchanger
having fins functioning as a condenser, the number of paths of an
outlet tube 207 for refrigerant is reduced, the outlet tube 207 is
disposed in the windward side with respect to the direction 203 of
air flow, and a fin 201 between the adjacent tubes 202 at the
downwind side is provided with a slit 208 in the longitudinal
direction of the fin 201.
[0014] With this structure, it is regarded that when the heat
exchanger is used as a condenser, since it is possible to increase
the speed in the tube mainly by the outlet tube 207 which is
excessively cooled region, the heat transfer performance is
enhanced, and by disposing the excessively cooled region having low
temperature in the windward side, it is possible to increase the
temperature difference between the air and the excessively cooled
region, and the condense performance can be enhanced.
[0015] Forth prior art (Japanese Patent Application No. S57-127732)
is shown in FIG. 12.
[0016] FIG. 12 is a perspective view showing a structure of a heat
exchanger having fins.
[0017] According to the fourth prior art, in the heat exchanger
having fins functioning as a condenser, the diameter of an outlet
tube 209 of refrigerant is made thinner than those of other
portions.
[0018] According to this structure, it is regarded that when the
heat exchanger is used as a condenser, since it is possible to
increase the speed in the tube by the outlet tube 209 which is
excessively cooled region, the heat transfer performance is
enhanced, and by disposing the excessively cooled region having low
temperature in the windward side, it is possible to increase the
temperature difference between the air and the excessively cooled
region, and the condense performance can be enhanced.
[0019] Fifth prior art (Japanese Patent Application No. H2-103355)
is shown in FIGS. 13a and 13b.
[0020] FIG. 13a is a perspective view showing a structure of a heat
exchanger having fins, and FIG. 13b is a sectional view of a heat
exchanger tube constituting the heat exchanger.
[0021] According to the fifth prior art, in the heat exchanger
having fins functioning as a condenser, inner rods 211 are inserted
in the heat exchanger tube 210 in the vicinity of the refrigerant
outlet.
[0022] With this structure, it is regarded that the heat exchanger
having fins used as the condenser can reduce the amount of
refrigerant charged by the inner rods 211 inserted in the excessive
cooled regions.
[0023] However, according to the structure of the first prior art,
since a wire of very small diameter is used as the coil, the volume
of the tube can not be remarkably reduced by inserting the coil.
Further, when the heat exchanger is used as a condenser, the inner
surface of the tube which is the heat transfer surface is liable to
be covered with a thick condensed liquid film and there is a
problem that the heat exchanging performance is lowered.
[0024] According to the structure of the second prior art, since
this prior art mainly aims at increasing the heat transfer area of
the inner surface of the heat transfer tube and at the turbulent
flow effect, and the thickness of the spacer is not specified, it
is judged that the thickness of the spacer is equal to that of the
heat exchanger tube, and the volume of the tube can not be
remarkably reduced by inserting the coil. Further, when the heat
exchanger is used as a condenser, the inner surface of the tube
which is the heat transfer surface is liable to be covered with a
thick condensed liquid film and there is a problem that the heat
exchanging performance is lowered.
[0025] According to the structure of the third prior art, the
current speed can be increased by minimizing the number of paths,
but the current speed of the minimum paths is the highest, and it
is not possible to further enhance the speed. Further, the speed
can only be changed at least for one heat exchanger tube by on heat
exchanger tube. It is not possible to reduce the volume in the
tube. Further, when the heat exchanger is used as a condenser, the
inner surface of the tube which is the heat transfer surface is
liable to be covered with a thick condensed liquid film and there
is a problem that the heat exchanging performance is lowered.
[0026] According to the structure of the fourth prior art, the
current speed in the thin tube can be increased, and the current
speed can be arbitrarily determined by selecting the diameter of
the thin tube, but in order to change the diameter of the thin
tube, it is necessary to change the molding dies of the fin having
a hole in which the thin tube is inserted. Therefore, it is
necessary to make a significant investment in the molding dies, and
it is not easy to change the diameter. It is not possible to reduce
the volume in the tube. Further, when the heat exchanger is used as
a condenser, the inner surface of the tube which is the heat
transfer surface is liable to be covered with a thick condensed
liquid film and there is a problem that the heat exchanging
performance is lowered.
[0027] According to the structure of the fifth prior art, this is
only effective to reduce the amount of refrigerant when the heat
exchanger is used as a condenser. When the heat exchanger is used
as an evaporator, since it is described that a member which
satisfies the pressure of 4 kg/cm.sup.2 is inserted to the outlet
of the condenser, this will bring about a remarkable increase in
pressure loss, and there is a problem that the evaporation ability
is remarkably lowered.
[0028] The present invention has been accomplished to solve the
problems of the prior art, and it is an object of the invention to
enhance the evaporation ability or to restrain the evaporation
ability from lowering while restraining the pressure loss at the
time of evaporation by inserting, into a heat exchanger tube, a
member which reduces the refrigerant flow passage as the mass flow
rate quality (dryness fraction) is increased.
[0029] Further, when the heat exchanger is used as a condenser, it
is another object of the invention to provide a heat exchanger
capable of reducing the thickness of the liquid film of an inner
surface of a tube by adhering the condensed liquid to an outer
surface of a member inserted into two-phase region, reducing the
cross-sectional area of the flow passage in the heat exchanger tube
by the insertion member, enhancing the current flow of the
refrigerant flowing in the heat exchanger tube, and enhancing the
heat exchanging performance.
[0030] Furthermore, it is another object of the invention to
provide a heat exchanger capable of reducing the amount of
refrigerant to be charged by reducing the volume in the heat
exchanger tube.
DISCLOSURE OF THE INVENTION
[0031] According to a first aspect, there is provided a heat
exchanger for exchanging heat between fluid flowing in a flow
passage in a heat exchanger tube and fluid flowing outside of the
heat exchanger tube, wherein a solid bar-like insertion member or a
hollow bar-like insertion member whose opposite ends are closed is
provided in the flow passage in which a fluid having phase change
flows in gas-liquid two phase state or liquid phase state, a cross
section of the insertion member is formed into a substantially
circle shape, a polygonal shape or a starlike shape, and a
cross-sectional area of a flow passage in which the fluid flows is
reduced as a mass flow rate quality of the fluid is reduced.
[0032] According to this construction, since the influence of the
pressure loss is increased as the mass flow rate quality is
increased, the pressure loss can effectively be reduced by widening
the flow passage having great mass flow rate quality, and the
evaporation ability can be enhanced or restrained from lowering.
When the heat exchanger is used as a condenser, if the current
speed of the refrigerant flowing the in heat exchanger tube in a
flow passage having small mass flow rate quality is increased, it
is possible to reduce the thickness of the liquid film of the inner
surface of the tube due to the condensed liquid, and it is possible
to obtain a heat exchanger having high heat exchanging performance
in the tube. Further, since the area of the outer surface of the
insertion member is increased by forming the cross section of the
insertion member into polygonal shape or starlike shape, the amount
of condensed liquid adhered to the insertion member is increased,
and it is possible to further reduce the thickness of the condensed
liquid film on the inner peripheral surface of the heat exchanger
tube, and to enhance the heat transfer coefficient. Further, since
the volume in the heat exchanger tube can be reduced, the amount of
refrigerant to be charged can be reduced.
[0033] According to a second aspect, there is provided a heat
exchanger for exchanging heat between fluid flowing in a flow
passage in a heat exchanger tube and fluid flowing outside of the
heat exchanger tube, wherein a bar-like insertion member is
provided in the flow passage in which a fluid having phase change
flows in gas-liquid two phase state or liquid phase state, and a
cross-sectional area of a flow passage in which the fluid flows is
reduced as a mass flow rate quality of the fluid is reduced.
[0034] According to this construction, since the influence of the
pressure loss is increased as the mass flow rate quality is
increased, the pressure loss can effectively be reduced by widening
the flow passage having great mass flow rate quality, and the
evaporation ability can be enhanced or restrained from lowering.
When the heat exchanger is used as a condenser, if the current
speed of the refrigerant flowing the in heat exchanger tube in a
flow passage having small mass flow rate quality is increased, it
is possible to reduce the thickness of the liquid film of the inner
surface of the tube due to the condensed liquid, and it is possible
to obtain a heat exchanger having high heat exchanging performance
in the tube. Further, since the volume in the heat exchanger tube
can be reduced, the amount of refrigerant to be charged can be
reduced.
[0035] According to a third aspect, in the first or second aspect,
a cross-sectional area of the insertion member is discontinuously
varied.
[0036] According to this construction, it is possible to reduce the
cross-sectional area of the flow passage in which the fluid flows
can be reduced as the mass flow rate quality of the fluid is
reduced by varying the cross-sectional area of the insertion
member. Further, it is possible to easily change the
cross-sectional area of the flow passage by combining insertion
members having different diameters.
[0037] According to a fourth aspect, in the first or second aspect,
a cross-sectional area of the insertion member is continuously
varied.
[0038] According to this construction, it is possible to reduce the
cross-sectional area of the flow passage in which the fluid flows
can be reduced as the mass flow rate quality of the fluid is
reduced by varying the cross-sectional area of the insertion
member. Further, it is possible to optimally reduce the pressure
loss and to exploit the full heat exchanging performance by
continuously changing the cross-sectional area of the insertion
member.
[0039] According to a fifth aspect, there is provided a heat
exchanger for exchanging heat between fluid flowing in a flow
passage in a heat exchanger tube and fluid flowing outside of the
heat exchanger tube, wherein a solid bar-like insertion member or a
hollow bar- like insertion member whose opposite ends are closed is
provided in the flow passage in which a fluid having phase change
flows in gas-liquid two phase state or liquid phase state, and a
cross section of the insertion member is formed into a
substantially circle shape, a polygonal shape or a starlike
shape.
[0040] According to this construction, when the heat exchanger is
used as a condenser, the thickness of the liquid film of the inner
surface of the tube by the condensed liquid in the two-phase region
or liquid phase can be reduced, and the current speed of the
refrigerant flowing in the heat exchanger tube can be enhanced so
that a heat exchanger having high heat exchanging performance in
the tube can be obtained. Further, since the area of the outer
surface of the insertion member is increased by forming the cross
section of the insertion member into polygonal shape or starlike
shape, the amount of condensed liquid adhered to the insertion
member is increased, and it is possible to further reduce the
thickness of the condensed liquid film on the inner peripheral
surface of the heat exchanger tube, and to enhance the heat
transfer coefficient. Further, since the volume in the heat
exchanger tube can be reduced, the amount of refrigerant to be
charged can be reduced.
[0041] According to a sixth aspect, in any one of the first, second
and fifth aspects, the insertion member is provided on its outer
surface with a groove, or a bump and a dip.
[0042] According to this construction, since the area of the outer
surface of the insertion member is increased, the amount of
condensed liquid adhered to the insertion member is increased, and
it is possible to further reduce the thickness of the condensed
liquid film on the inner peripheral surface of the heat exchanger
tube, and to enhance the heat transfer coefficient.
[0043] According to a seventh aspect, in any one of the first,
second and fifth aspects, the insertion member is made of porous
material.
[0044] According to this construction, since the area of the outer
surface of the insertion member is increased by the porous
material, the amount of condensed liquid adhered to the insertion
member is increased, and it is possible to further reduce the
thickness of the condensed liquid film on the inner peripheral
surface of the heat exchanger tube, and to enhance the heat
transfer coefficient.
[0045] According to an eighth aspect, in any one of the first,
second and fifth aspects, the insertion member is provided in
plural into bundle.
[0046] According to this construction, since the plurality of
insertion members are provided, the area of the outer surfaces of
the insertion members is increased, the amount of condensed liquid
adhered to the insertion member is increased, and it is possible to
further reduce the thickness of the condensed liquid film on the
inner peripheral surface of the heat exchanger tube, and to enhance
the heat transfer coefficient.
[0047] According to a ninth aspect, in any one of the first, second
and fifth aspects, a refrigerant comprising hydro fluorocarbon
(HFC) or hydrocarbon (HC) as main component is used as the fluid
flowing in the flow passage in the heat exchanger tube.
[0048] According to this construction, the refrigerant comprising
hydro fluorocarbon (HFC) or hydrocarbon (HC) as main component has
higher refrigerant density at the same cycle point than
conventional R22 and thus has lower current speed, and the pressure
loss is lowered to about 70% when the refrigerant has the same
ability as the conventional R22. For this reason, the heat transfer
coefficient is enhanced and the heat exchanging coefficient is also
enhanced especially by using R410A, propane (R290) or the like as
refrigerant. Further, if the hydro fluorocarbon (HFC) or
hydrocarbon (HC) is used, the value of the ozone destroy potential
(ODP) is 0. Although the value of the global warming potential
(GWP) of the hydro fluorocarbon (HFC) is high, the global warming
potential (GWP) of the hydrocarbon (HC) is extremely closer to 0.
Therefore, the environmental problem can be overcome.
[0049] According to a tenth aspect, in the third aspect, the
insertion member is provided on its outer surface with a groove, or
a bump and a dip.
[0050] According to this construction, since the area of the outer
surface of the insertion member is increased, the amount of
condensed liquid adhered to the insertion member is increased, and
it is possible to further reduce the thickness of the condensed
liquid film on the inner peripheral surface of the heat exchanger
tube, and to enhance the heat transfer coefficient.
[0051] According to a eleventh aspect, in the third aspect, the
insertion member is made of porous material.
[0052] According to this construction, since the area of the outer
surface of the insertion member is increased by the porous
material, the amount of condensed liquid adhered to the insertion
member is increased, and it is possible to further reduce the
thickness of the condensed liquid film on the inner peripheral
surface of the heat exchanger tube, and to enhance the heat
transfer coefficient.
[0053] According to an twelfth aspect, in the third aspect, the
insertion member is provided in plural into bundle.
[0054] According to this construction, since the plurality of
insertion members are provided, the area of the outer surfaces of
the insertion members is increased, the amount of condensed liquid
adhered to the insertion member is increased, and it is possible to
further reduce the thickness of the condensed liquid film on the
inner peripheral surface of the heat exchanger tube, and to enhance
the heat transfer coefficient.
[0055] According to a thirteenth aspect, in the third aspect, a
refrigerant comprising hydro fluorocarbon (HFC) or hydrocarbon (HC)
as main component is used as the fluid flowing in the flow passage
in the heat exchanger tube.
[0056] According to this construction, the refrigerant comprising
hydro fluorocarbon (HFC) or hydrocarbon (HC) as main component has
higher refrigerant density at the same cycle point than
conventional R22 and thus has lower current speed, and the pressure
loss is lowered to about 70% when the refrigerant has the same
ability as the conventional R22. For this reason, the heat transfer
coefficient is enhanced and the heat exchanging coefficient is also
enhanced especially by using R410A, propane (R290) or the like as
refrigerant. Further, if the hydro fluorocarbon (HFC) or
hydrocarbon (HC) is used, the value of the ozone destroy potential
(ODP) is 0. Although the value of the global warming potential
(GWP) of the hydro fluorocarbon (HFC) is high, the global warming
potential (GWP) of the hydrocarbon (HC) is extremely closer to 0.
Therefore, the environmental problem can be overcome.
[0057] According to a fourteenth aspect, in the fourth aspect, the
insertion member is provided on its outer surface with a groove, or
a bump and a dip.
[0058] According to this construction, since the area of the outer
surface of the insertion member is increased, the amount of
condensed liquid adhered to the insertion member is increased, and
it is possible to further reduce the thickness of the condensed
liquid film on the inner peripheral surface of the heat exchanger
tube, and to enhance the heat transfer coefficient.
[0059] According to a fifteenth aspect, in the fourth aspect, the
insertion member is made of porous material.
[0060] According to this construction, since the area of the outer
surface of the insertion member is increased by the porous
material, the amount of condensed liquid adhered to the insertion
member is increased, and it is possible to further reduce the
thickness of the condensed liquid film on the inner peripheral
surface of the heat exchanger tube, and to enhance the heat
transfer coefficient.
[0061] According to an sixteenth aspect, in the fourth aspect, the
insertion member is provided in plural into bundle.
[0062] According to this construction, since the plurality of
insertion members are provided, the area of the outer surfaces of
the insertion members is increased, the amount of condensed liquid
adhered to the insertion member is increased, and it is possible to
further reduce the thickness of the condensed liquid film on the
inner peripheral surface of the heat exchanger tube, and to enhance
the heat transfer coefficient.
[0063] According to a seventeenth aspect, in the fourth aspect, a
refrigerant comprising hydro fluorocarbon (HFC) or hydrocarbon (HC)
as main component is used as the fluid flowing in the flow passage
in the heat exchanger tube.
[0064] According to this construction, the refrigerant comprising
hydro fluorocarbon (HFC) or hydrocarbon (HC) as main component has
higher refrigerant density at the same cycle point than
conventional R22 and thus has lower current speed, and the pressure
loss is lowered to about 70% when the refrigerant has the same
ability as the conventional R22. For this reason, the heat transfer
coefficient is enhanced and the heat exchanging coefficient is also
enhanced especially by using R410A, propane (R290) or the like as
refrigerant. Further, if the hydro fluorocarbon (HFC) or
hydrocarbon (HC) is used, the value of the ozone destroy potential
(ODP) is 0. Although the value of the global warming potential
(GWP) of the hydro fluorocarbon (HFC) is high, the global warming
potential (GWP) of the hydrocarbon (HC) is extremely closer to 0.
Therefore, the environmental problem can be overcome.
BRIEF DESCRIPTION OF DRAWINGS
[0065] FIG. 1a is a sectional view of a heat exchanger having fins
according to an embodiment of the present invention taken along the
center line of a heat exchanger tube;
[0066] FIG. 1b is a sectional view taken along the line A-A in FIG.
1a;
[0067] FIG. 2a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube;
[0068] FIG. 2b is a sectional view taken along the line A-A in FIG.
2a;
[0069] FIG. 3a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube;
[0070] FIG. 3b is a sectional view taken along the line A-A in FIG.
3a;
[0071] FIG. 4a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube;
[0072] FIG. 4b is a sectional view taken along the line A-A in FIG.
4a;
[0073] FIG. 5a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube;
[0074] FIG. 5b is a sectional view taken along the line A-A in FIG.
5a;
[0075] FIG. 6a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube;
[0076] FIG. 6b is a sectional view taken along the line A-A in FIG.
6a;
[0077] FIG. 7a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube;
[0078] FIG. 7b is a sectional view taken along the line A-A in FIG.
7a;
[0079] FIG. 8 is a perspective view of the heat exchanger having
fins;
[0080] FIG. 9a is a vertical sectional view showing a portion of a
heat exchanger tube according to a first prior art;
[0081] FIG. 9b is an enlarged sectional view of an essential
portion showing an inner wall surface of the heat exchanger
tube;
[0082] FIG. 10 is a sectional view of a heat exchanger having fins
according to a second prior art taken along the surface passing
through the center line of a heat exchanger tube;
[0083] FIG. 11 is a perspective view showing a construction of a
heat exchanger having fins according to a third prior art;
[0084] FIG. 12 is a perspective view showing a construction of a
heat exchanger having fins according to a fourth prior art;
[0085] FIG. 13a is a perspective view showing a construction of a
heat exchanger having fins according to a fifth prior art;
[0086] FIG. 13b is a sectional view of a heat exchanger tube
constituting the heat exchanger; and
[0087] FIG. 14 is an image view in which operation points of
refrigerating cycle are added to Mollier chart.
BEST MODE FOR CARRYING OUT THE INVENTION
[0088] Embodiments of the present invention will be explained with
reference to the drawings. Although heat exchangers having fins
will be explained in the following description of the embodiments,
effect of the present invention is obtained in a flow passage in
which refrigerant having phase change characteristics flows, and
the same effect can be obtained even in inside or outside of inner
tube of a heat exchanger comprising only a heat exchanger tube such
as double tube heat exchanger if the fluid has phase change
characteristic flows.
First Embodiment
[0089] FIG. 1a is a sectional view of a heat exchanger having fins
taken along the center line of a heat exchanger tube and FIG. 1b is
a sectional view taken along the line A-A in FIG. 1a. FIG. 14 is an
image view in which operation points of refrigerating cycle are
added to Mollier chart.
[0090] In FIGS. 1a and 1b, the reference number 11 represents fins,
12 represents a heat exchanger tube, 13A represents an insertion
member having constant cross-sectional area, and 13B represents an
insertion member having cross-sectional area which is changed
continuously depending on position of a flow passage. The heat
exchanger tube 12 comprises three tubes 12A, 12B and 12C formed
into U-shape, a U-bent tube 12D connecting one ends of the tube 12A
and the tube 12B, and a U-bent tube 12E connecting the other end of
the tube 12B and one end of the tube 12C. Although the heat
exchanger tube 12 comprises three tubes 12A, 12B and 12C in this
embodiment, the number of tubes maybe changed in accordance with
ability of the heat exchanger. An insertion member 13A is provided
in a flow passage 14A at the side of a heat exchanger tube end C of
the tube 12A, and an insertion member 13B is provided in a flow
passage 14B at the side of the U-bent tube 12D. The insertion
member 13B is disposed such that its end having small
cross-sectional area is located at the opening side of the tube
12A.
[0091] When this heat exchanger having fins is used as a condenser,
a heat exchanger end B is an inlet of fluid flowing in the flow
passage, and a heat exchanger tube end C is an outlet of fluid
flowing in the flow passage. When the heat exchanger having fins is
used as the condenser, gaseous fluid flows in from the heat
exchanger tube end B, and liquid fluid flows out from the heat
exchanger tube end C. Therefore, as the fluid flows from the heat
exchanger tube end B to the heat exchanger tube end C, the mass
flow rate quality of the fluid becomes smaller. The arrow indicated
the direction of fluid flowing in the flow passage.
[0092] In FIG. 14, a line 212 indicates a saturated liquid line, a
line 213 indicates a saturated gas line, a solid line 225 indicates
an operation line when the insertion member is inserted, a broken
line 226 indicates an operation line at the time of normal time
when the member is not inserted, a point 214 indicates a suction
point of a compressor, a point 215 indicates an inlet point of a
condenser, a point 217 indicates an outlet point of the condenser
at the time of normal time when the member is not inserted, a point
219 indicates an inlet point of an evaporator when the member is
inserted, a point 220 indicates an inlet point of the evaporator at
the time of normal time when the member is not inserted, a point
222 indicates an outlet point of the evaporator, a point 216
indicates an average condensation temperature, a point 221
indicates an average evaporation temperature, an area 223 indicates
an area in the vicinity of the condenser outlet, and an area 224
indicates an area in the vicinity of the evaporator inlet.
[0093] When the heat exchanger is used as a condenser, in FIG. 1a,
fluid flowing in the heat exchanger tube flows in from the side of
the heat exchanger end B and flows out toward the heat exchanger
end C. During that time, the heat exchange is carried out between
the fluid and air current flowing in the gap between the fins
provided around the outer periphery of the heat exchanger tube 12.
The flow passage 14B is gradually narrowed by the insertion member
13B, and the flow passage 14A is narrowed by the insertion member
13A. Therefore, the speed the fluid flowing in the tube 12A
gradually becomes faster in the flow passage 14B and the fluid
flows in the flow passage 14A at the highest speed and thus, the
heat transfer coefficient in the tube is enhanced.
[0094] In the present embodiment, since the insertion members 13A
and 13B are inserted in the vicinity 223 of the condenser outlet,
the pressure loss is increased only in the vicinity of the
condenser outlet 223 as shown in FIG. 14, and the average
condensation temperature 216 is restrained from being lowered. In a
gas-liquid two-phase region, since the condensed liquid is also
adhered to the outer peripheral surfaces of the insertion members
13A and 13B, the thickness of the condensed liquid film of the
inner peripheral surface of the tube 12A can be reduced, and the
heat transfer coefficient in the tube can be enhanced. Further, by
providing the insertion members 13A and 13B, the volume in the tube
12A can be reduced, and the amount of refrigerant to be charged can
be reduced.
[0095] When the heat exchanger is used as the evaporator, in FIG.
1a, the fluid flowing in the heat exchanger tube flows in the
opposite direction from that when the heat exchanger is used as the
condenser, the fluid flowing in the heat exchanger tube flows in
from the side of the heat exchanger end C and flows out toward the
heat exchanger end B. During that time, the heat exchange is
carried out between the fluid and air current flowing in the gap
between the fins provided around the outer periphery of the heat
exchanger tube 12. The flow passage 14A is gradually narrowed by
the insertion member 13A, and the flow passage 14B is gradually
narrowed by the insertion member 13B. Therefore, the speed the
fluid flowing in the tube 12A becomes faster and thus, the heat
transfer coefficient in the tube is enhanced.
[0096] In the present embodiment, since the insertion members 13A
and 13B are inserted in the vicinity 224 of the evaporator, as
shown with the solid line 225 in FIG. 14, the pressure loss is
increased in the vicinity 224 of the evaporator inlet, and as the
mass flow rate quality is increased, the cross-sectional area of
the flow passage is increased and thus, the pressure loss is
reduced. Therefore, even if the pressure loss is increased, the
pressure loss is increased only in the vicinity 224 of the
evaporator, the heat transfer coefficient is enhanced due to the
increase in flowing speed of the fluid, and the evaporation ability
can be enhanced. Therefore, it is possible to restrain at least the
evaporation ability from being lowered.
[0097] It is preferable that the shape of the cross section of each
of the insertion members 13A and 13B is polygonal shape or starlike
shape, in addition to substantially circular shape. Each of the
insertion members 13A and 13B comprises a solid bar-member or a
hollow bar-like member whose opposite ends are closed. The material
of the each of the insertion members 13A and 13B is metal such as
iron or aluminum or resin having corrosion resistance with respect
to the refrigerant.
Second Embodiment
[0098] FIG. 2a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube, and FIG. 2b is a sectional
view taken along the line A-A in FIG. 2a. The same members as those
in the above embodiment are designated with the same reference
numbers, and detailed explanation thereof will be omitted.
[0099] In the second embodiment, as shown in FIGS. 2a and 2b,
insertion members 23A, 23B and 23C are provided in the flow passage
14A of the tube 12A. Here, the cross-sectional area of each of the
insertion members 23A, 23B and 23C is constant, the cross-sectional
area of the insertion member 23A is greater than that of the
insertion member 23B, and the cross-sectional area of the insertion
member 23B is greater than that of the insertion member 23C. The
insertion members 23A, 23B and 23C are connected in this order. The
insertion member 23A having the greatest cross-sectional area is
disposed at the side of the heat exchanger tube end C.
[0100] Since the insertion members comprise the insertion members
23A, 23B and 23C, and the insertion ember 23A is disposed at the
side of the heat exchanger tube end C in this manner, the flow
passage 14 in which the fluid can flow is gradually narrowed as the
mass flow rate quality becomes smaller, the current speed of the
fluid flowing in the flow passage 14 is enhanced, and the heat
transfer coefficient in the tube is enhanced.
[0101] When the heat exchanger is used as the condenser, in the
present embodiment also, since the insertion members 23A, 23B and
23C are inserted in the vicinity 223 of the condenser outlet, the
pressure loss is increased only in the vicinity of the condenser
outlet 223, and the average condensation temperature 216 is
restrained from being lowered. In a gas-liquid two-phase region,
since the condensed liquid is also adhered to the outer peripheral
surfaces of the insertion members 23A, 23B and 23C, the thickness
of the condensed liquid film of the inner peripheral surface of the
tube 12A can be reduced, and the heat transfer coefficient in the
tube can be enhanced. Further, by providing the insertion members
23A, 23B and 23C, the volume in the tube 12A can be reduced, and
the amount of refrigerant to be charged can be reduced.
[0102] When the heat exchanger is used as the evaporator, in the
present embodiment also, since the insertion members 23A, 23B and
23C are inserted in the vicinity 224 of the evaporator, as shown
with the solid line 225 in FIG. 14, the pressure loss is increased
in the vicinity 224 of the evaporator inlet, and as the mass flow
rate quality is increased, the cross-sectional area of the flow
passage is increased and thus, the pressure loss is reduced.
Therefore, even if the pressure loss is increased, the pressure
loss is increased only in the vicinity 224 of the evaporator, the
heat transfer coefficient is enhanced due to the increase in
flowing speed of the fluid, and the evaporation ability can be
enhanced. Therefore, it is possible to restrain at least the
evaporation ability from being lowered.
[0103] Further, as in the present embodiment, it is possible to
easily vary the cross-sectional area of the flow passage by
combining insertion members having different diameters.
[0104] Although the description has been made in the present
embodiment while taking, as an example, the case in which only the
flow passage 14A is provided with the insertion members, the flow
passage 14B may be provided with the insertion member 24B, and the
tube 12B may be provided at its lower flow passage with the
insertion member 24C, and insertion members having different
cross-sectional areas may be provided in steps (in front and behind
the bent portion of the heat exchanger tubes) of the tubes.
Third Embodiment
[0105] FIG. 3a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube, and FIG. 3b is a sectional
view taken along the line A-A in FIG. 3a. The same members as those
in the above embodiment are designated with the same reference
numbers, and detailed explanation thereof will be omitted.
[0106] In the third embodiment, as shown in FIGS. 3a and 3b, an
insertion member 33 whose cross-sectional area is continuously
varied is provided in the flow passage 14A of the tube 12A. The
insertion member 33 is disposed such that its end having greater
cross-sectional area is located at the side of the heat exchanger
tube end C.
[0107] Since the insertion member comprises the insertion member 33
whose cross-sectional area is continuously varied, and the
insertion member 33 is disposed such that its end having greater
cross-sectional area is located at the side of the heat exchanger
tube end C in this manner, the flow passage 14 in which the fluid
can flow is gradually narrowed as the mass flow rate quality
becomes smaller, the current speed of the fluid flowing in the flow
passage 14 is enhanced, and the heat transfer coefficient in the
tube is enhanced.
[0108] When the heat exchanger is used as the condenser, in the
present embodiment also, since the insertion member 33 is inserted
in the vicinity 223 of the condenser outlet, the pressure loss is
increased only in the vicinity of the condenser outlet 223, and the
average condensation temperature 216 is restrained from being
lowered. In a gas-liquid two-phase region, since the condensed
liquid is also adhered to the outer peripheral surface of the
insertion member 33, the thickness of the condensed liquid film of
the inner peripheral surface of the tube 12A can be reduced, and
the heat transfer coefficient in the tube can be enhanced. Further,
by providing the insertion member 33, the volume in the tube 12A
can be reduced, and the amount of refrigerant to be charged can be
reduced.
[0109] Further, it is possible to optimally reduce the pressure
loss and to exploit the full heat exchanging performance by
continuously changing the cross-sectional area of the insertion
member.
[0110] When the heat exchanger is used as the evaporator, in the
present embodiment also, since the insertion member 33 is inserted
in the vicinity 224 of the evaporator, as shown with the solid line
225 in FIG. 14, the pressure loss is increased in the vicinity 224
of the evaporator inlet, and as the mass flow rate quality is
increased, the cross-sectional area of the flow passage is
increased and thus, the pressure loss is reduced. Therefore, even
if the pressure loss is increased, the pressure loss is increased
only in the vicinity 224 of the evaporator, the heat transfer
coefficient is enhanced due to the increase in flowing speed of the
fluid, and the evaporation ability can be enhanced. Therefore, it
is possible to restrain at least the evaporation ability from being
lowered.
[0111] Although the description has been made in the present
embodiment while taking, as an example, the case in which only the
flow passage 14A is provided with the insertion member, the flow
passage 14B may also be provided with an insertion member, and the
tube 12B may also be provided at its lower flow passage with an
insertion member. When the insertion members are provided in a
plurality of tubes, it is preferable that the cross-sectional area
of each of the insertion members is continuously varied.
Fourth Embodiment
[0112] FIG. 4a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube, and FIG. 4b is a sectional
view taken along the line A-A in FIG. 4a. The same members as those
in the above embodiment are designated with the same reference
numbers, and detailed explanation thereof will be omitted.
[0113] As shown in FIGS. 4a and 4b, insertion members 43 each
having a constant cross-sectional area are provided in flow
passages 14A and 14B of the tube 12A as well as in flow passages
14C and 14D of the tube 12B. No insertion members is provided in
each of the flow passages 14E and 14F of the tube 12C.
[0114] Since the flow passages 14A, 14B, 14C and 14D having small
mass flow rate qualities are narrower than the flow passages 14E
and 14F having great mass flow rate qualities, the current speed of
the fluid flowing in the flow passages 14A, 14B, 14C and 14D is
enhanced, and the heat transfer coefficient in the tube is
enhanced.
[0115] When the heat exchanger is used as the condenser, in the
present embodiment also, since the insertion member 43 is inserted
at the side of the condenser outlet, the average condensation
temperature 216 is restrained from being lowered. In a gas-liquid
two-phase region, since the condensed liquid is also adhered to the
outer peripheral surface of the insertion member 43, the thickness
of the condensed liquid film of the inner peripheral surfaces of
the tubes 12A and 12B can be reduced, and the heat transfer
coefficient in the tube can be enhanced. Further, by providing the
insertion member 43, the volume in each of the tubes 12A and 12B
can be reduced, and the amount of refrigerant to be charged can be
reduced.
[0116] When the heat exchanger is used as the evaporator, in the
present embodiment also, since the insertion member 43 is inserted
at the side of the evaporator inlet, the pressure loss is great at
the side of the evaporator inlet, and in a place where the mass
flow rate quality is great, the cross-sectional area of the flow
passage is great and thus, the pressure loss is reduced. Therefore,
even if the pressure loss is increased, the pressure loss is
increased only at the side of the evaporator inlet, the heat
transfer coefficient is enhanced due to the increase in flowing
speed of the fluid, and the evaporation ability can be enhanced.
Therefore, it is possible to restrain at least the evaporation
ability from being lowered.
[0117] Further, by using the insertion members 43 each having the
constant cross-sectional area, since a large number of the same
members, it is possible to reduce the costs of the insertion
members to the minimum.
Fifth Embodiment
[0118] FIG. 5a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube, and FIG. 5b is a sectional
view taken along the line A-A in FIG. 5a. The same members as those
in the above embodiment are designated with the same reference
numbers, and detailed explanation thereof will be omitted.
[0119] As shown in FIGS. 5a and 5b, in a flow passage 14A of the
tube 12A, an insertion member 53 whose cross-sectional area is
continuously varied and formed with a plurality of grooves 53A in a
longitudinal direction of an outer surface thereof is provided. The
insertion member 53 is disposed such that its one end having
greater cross-sectional area is located at the side of the heat
exchanger tube end C.
[0120] Since the insertion member comprises the insertion member 53
whose cross-sectional area is continuously varied, and the
insertion member 33 is disposed such that its end having greater
cross-sectional area is located at the side of the heat exchanger
tube end C in this manner, the flow passage 14 in which the fluid
can flow is gradually narrowed as the mass flow rate quality
becomes smaller, the current speed of the fluid flowing in the flow
passage 14 is enhanced, and the heat transfer coefficient in the
tube is enhanced.
[0121] When the heat exchanger is used as the condenser, in the
present embodiment also, since the insertion member 53 is inserted
in the vicinity 223 of the condenser outlet, the pressure loss is
increased only in the vicinity of the condenser outlet 223, and the
average condensation temperature 216 is restrained from being
lowered. The condensed liquid is adhered to the outer peripheral
surface of the insertion member 53, but since the amount of the
condensed liquid adhered to the insertion member 53 is increased
because the outer area of the insertion member 53 is increased due
to the grooves 53A, the thickness of the condensed liquid film of
the inner peripheral surface of the tube 12A can further be
reduced, and the heat transfer coefficient in the tube is enhanced.
Further, the volume in the heat exchanger tube can be reduced by
the insertion member, and the amount of refrigerant to be charged
can be reduced.
[0122] Further, since the diameter of the insertion member is
continuously varied, it is possible to optimally reduce the
pressure and to exploit the full ability.
[0123] When the heat exchanger is used as the evaporator, in the
present embodiment also, since the insertion member 53 is inserted
in the vicinity 224 of the evaporator, as shown with the solid line
225 in FIG. 14, the pressure loss is increased in the vicinity 224
of the evaporator inlet, and as the mass flow rate quality is
increased, the cross-sectional area of the flow passage is
increased and thus, the pressure loss is reduced. Therefore, even
if the pressure loss is increased, the pressure loss is increased
only in the vicinity 224 of the evaporator, the heat transfer
coefficient is enhanced due to the increase in flowing speed of the
fluid, and the evaporation ability can be enhanced. Therefore, it
is possible to restrain at least the evaporation ability from being
lowered.
[0124] Although FIG. 5a shows straight grooves, if helical grooves
are provided, turbulent flow is promoted, which enhances the heat
transfer coefficient and thus, the ability is enhanced.
[0125] Further, the cross-sectional area of the insertion member 53
may be varied in front and behind the bent portion of the heat
exchanger tube. The same effect can be obtained even if the groove
is formed with bumps and dips by dimple processing.
Sixth Embodiment
[0126] FIG. 6a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube, and FIG. 6b is a sectional
view taken along the line A-A in FIG. 6a. The same members as those
in the above embodiment are designated with the same reference
numbers, and detailed explanation thereof will be omitted.
[0127] In the sixth embodiment, as shown in FIGS. 6a and 6b, an
insertion member 63 made of porous material and whose
cross-sectional area is continuously varied is provided in the flow
passage 14A of the tube 12A. The insertion member 63 is disposed
such that its one end having greater cross-sectional area is
located at the side of the heat exchanger tube end C.
[0128] Since the insertion member comprises the insertion member 63
whose cross-sectional area is continuously varied, and the
insertion member 63 is disposed such that its end having greater
cross-sectional area is located at the side of the heat exchanger
tube end C in this manner, the flow passage 14A in which the fluid
can flow is gradually narrowed as the mass flow rate quality
becomes smaller, the current speed of the fluid flowing in the flow
passage 14A is enhanced, and the heat transfer coefficient in the
tube is enhanced.
[0129] When the heat exchanger is used as the condenser, in the
present embodiment also, since the insertion member 63 is inserted
in the vicinity 223 of the condenser outlet, the pressure loss is
increased only in the vicinity of the condenser outlet 223, and the
average condensation temperature 216 is restrained from being
lowered. The condensed liquid is adhered to the outer peripheral
surface of the insertion member 63, but since the insertion member
63 is formed into porous shape, the outer area of the insertion
member 63 can be increased, the thickness of the condensed liquid
film of the inner peripheral surface of the tube 12A can further be
reduced, and the heat transfer coefficient in the tube is enhanced.
Further, the volume in the heat exchanger tube can be reduced by
the insertion member, and the amount of refrigerant to be charged
can be reduced.
[0130] Further, since the diameter of the insertion member 63 is
continuously varied, it is possible to optimally reduce the
pressure and to exploit the full ability.
[0131] When the heat exchanger is used as the evaporator, in the
present embodiment also, since the insertion member 63 is inserted
in the vicinity 224 of the evaporator, as shown with the solid line
225 in FIG. 14, the pressure loss is increased in the vicinity 224
of the evaporator inlet, and as the mass flow rate quality is
increased, the cross-sectional area of the flow passage is
increased and thus, the pressure loss is reduced. Therefore, even
if the pressure loss is increased, the pressure loss is increased
only in the vicinity 224 of the evaporator, the heat transfer
coefficient is enhanced due to the increase in flowing speed of the
fluid, and the evaporation ability can be enhanced. Therefore, it
is possible to restrain at least the evaporation ability from being
lowered.
[0132] Although FIG. 6a shows the member formed by hardening fine
particles, the same effect can be obtained even if the porous
member is formed by adhering the particles onto a smooth outer
surface in view of strength. Further, even if particles having
different particle diameter are mixed, the same effect can be
obtained. The cross-sectional area of the insertion member 63 may
be varied in front of and behind the bent portion of the heat
exchanger tube.
Seventh Embodiment
[0133] FIG. 7a is a sectional view of a heat exchanger having fins
according to another embodiment of the invention taken along the
center line of a heat exchanger tube, and FIG. 7b is a sectional
view taken along the line A-A in FIG. 7a. The same members as those
in the above embodiment are designated with the same reference
numbers, and detailed explanation thereof will be omitted.
[0134] According to the present embodiment, as shown in FIGS. 7a
and 7b, a plurality of insertion members 73A, 73B and 73C are tied
in a bundle and provided in the flow passage 14A of the tube 12A.
The cross-sectional area of each of the insertion members 73 is
continuously varied. The insertion member 73 is disposed such that
its one end having greater cross-sectional area is located at the
side of the heat exchanger tube end C.
[0135] Since the insertion member comprises the insertion member 73
whose cross-sectional area is continuously varied, and the
insertion member 73 is disposed such that its end having greater
cross-sectional area is located at the side of the heat exchanger
tube end C in this manner, the flow passage 14A in which the fluid
can flow is gradually narrowed as the mass flow rate quality
becomes smaller, the current speed of the fluid flowing in the flow
passage 14A is enhanced, and the heat transfer coefficient in the
tube is enhanced.
[0136] When the heat exchanger is used as the condenser, in the
present embodiment also, since the insertion member 73 is inserted
in the vicinity 223 of the condenser outlet, the pressure loss is
increased only in the vicinity of the condenser outlet 223, and the
average condensation temperature 216 is restrained from being
lowered. The condensed liquid is adhered to the outer peripheral
surface of the insertion member 73, but since the plurality of
insertion members 73A, 73B and 73C are tied into bundle, the outer
area of the insertion member 73 can be increased, the thickness of
the condensed liquid film of the inner peripheral surface of the
tube 12A can further be reduced, and the heat transfer coefficient
in the tube is enhanced. Further, the volume in the heat exchanger
tube can be reduced by the insertion member, and the amount of
refrigerant to be charged can be reduced.
[0137] Further, since the diameter of the insertion member 73 is
continuously varied, it is possible to optimally reduce the
pressure and to exploit the full ability.
[0138] When the heat exchanger is used as the evaporator, in the
present embodiment also, since the insertion member 73 is inserted
in the vicinity 224 of the evaporator, as shown with the solid line
225 in FIG. 14, the pressure loss is increased in the vicinity 224
of the evaporator inlet, and as the mass flow rate quality is
increased, the cross-sectional area of the flow passage is
increased and thus, the pressure loss is reduced. Therefore, even
if the pressure loss is increased, the pressure loss is increased
only in the vicinity 224 of the evaporator, the heat transfer
coefficient is enhanced due to the increase in flowing speed of the
fluid, and the evaporation ability can be enhanced. Therefore, it
is possible to restrain at least the evaporation ability from being
lowered.
[0139] Further, as shown in FIG. 8, when the heat exchanger tube is
bent to form a heat exchanger, it is possible to restrain the
deformation of the member at the bent portion and thus, the
processing is easy.
[0140] Although FIG. 7a shows straight bars, if helically twisted
bars are combined, turbulent flow is promoted, which enhances the
heat transfer coefficient and thus, the ability is enhanced.
[0141] Although the fluid is not specifically described in the
above embodiments, the following refrigerant can be used.
[0142] Although a single refrigerant (R22) is conventionally used
as a refrigerant used for an air conditioner, single refrigerant or
azeotropic refrigerant having small temperature gradient of air
temperature in a refrigeration cycle, such as R32/R125 (50/50 wt %)
(which will be referred to as R410A hereinafter) in hydro
fluorocarbon (HFC), or propane (R290) in hydrocarbon (HC) may be
used as a substitutable refrigerant. Each of these refrigerants has
greater refrigerant density at the same cycle point as compared
with the conventional R22 in the refrigeration cycle and thus, has
characteristic that the current speed is reduced.
[0143] That is, when the same ability is required, the pressure
loss of the R410 in a heat exchanger or a tube is about 70% of that
of the R22.
[0144] For this reason, if refrigerant such as R410A, propane
(R290) or the like is used, the heat transfer coefficient is
enhanced, and the efficient of the heat exchanger is enhanced.
Further, if the hydro fluorocarbon (HFC) or hydrocarbon (HC) is
used, the value of the ozone destroy potential (ODP) is 0. Although
the value of the global warming potential (GWP) of the hydro
fluorocarbon (HFC) is high, the global warming potential (GWP) of
the hydrocarbon (HC) is extremely closer to 0. Therefore, the
environmental problem can be overcome.
* * * * *