U.S. patent application number 12/850348 was filed with the patent office on 2011-02-10 for heat exchanger.
This patent application is currently assigned to KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. Invention is credited to Hirokuni AKIYAMA, Naoto MORISAKU.
Application Number | 20110030389 12/850348 |
Document ID | / |
Family ID | 43063497 |
Filed Date | 2011-02-10 |
United States Patent
Application |
20110030389 |
Kind Code |
A1 |
MORISAKU; Naoto ; et
al. |
February 10, 2011 |
HEAT EXCHANGER
Abstract
A heat exchanger includes a thermoelectric module. A first fluid
passage is arranged at a heat dissipation side of the
thermoelectric module and a second fluid passage is arranged at a
heat absorption side of the thermoelectric module. The
thermoelectric module includes P type and N type thermoelectric
semiconductor elements. An electrical insulator couples the P type
and N type thermoelectric semiconductor elements. Heat dissipation
side electrodes are exposed in the first fluid passage and heat
absorption side electrodes are exposed in the second fluid passage.
At least the heat dissipation side of the thermoelectric module
includes valleys and ridges with the heat dissipation side
electrode being free from projections.
Inventors: |
MORISAKU; Naoto;
(Kariya-shi, JP) ; AKIYAMA; Hirokuni; (Kariya-shi,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W., SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
Kariya-shi
JP
|
Family ID: |
43063497 |
Appl. No.: |
12/850348 |
Filed: |
August 4, 2010 |
Current U.S.
Class: |
62/3.7 |
Current CPC
Class: |
H01L 35/30 20130101 |
Class at
Publication: |
62/3.7 |
International
Class: |
F25B 21/02 20060101
F25B021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2009 |
JP |
2009-182502 |
Claims
1. A heat exchanger comprising: a thermoelectric module, in which
heat exchange is performed between a first fluid flowing through a
first fluid passage arranged at a heat dissipation side of the
thermoelectric module and a second fluid flowing through a second
fluid passage arranged at a heat absorption side of the
thermoelectric module, the thermoelectric module including: a
plurality of P type thermoelectric semiconductor elements and a
plurality of N type thermoelectric semiconductor elements that are
thermally arranged in parallel; heat dissipation side electrodes
formed by planar plates and heat absorption side electrodes formed
by planar plates that electrically connect in series the P type
thermoelectric semiconductor elements and the N type thermoelectric
semiconductor elements; an electrical insulator that couples the P
type thermoelectric semiconductor elements and the N type
thermoelectric semiconductor elements so as to impede fluid
movement between the first fluid passage and the second fluid
passage; wherein the heat dissipation side electrodes are exposed
in the first fluid passage and the heat absorption side electrodes
are exposed in the second fluid passage; and at least the heat
dissipation side of the thermoelectric module includes valleys and
ridges with the heat dissipation side electrodes being free from
projections.
2. The heat exchanger according to claim 1, wherein the valleys and
ridges are formed by part of the electrical insulator projected
into the first fluid passage further from the heat dissipation side
electrode.
3. The heat exchanger according to claim 2, the part of the
electrical insulator forms a plurality of flow paths in the first
fluid passage.
4. The heat exchanger according to claim 2, wherein the part of the
electrical insulator projected into the first fluid passage is
formed integrally with part of the electrical insulator that
couples the P type thermoelectric semiconductor elements and the N
type thermoelectric semiconductor elements.
5. The heat exchanger according to claim 2, wherein the part of the
electrical insulator projected into the first fluid passage is
formed discretely from part of the electrical insulator that
couples the P type thermoelectric semiconductor elements and the N
type thermoelectric semiconductor elements and adhered to said
part.
6. The heat exchanger according to claim 1, wherein the valleys and
ridges are formed by coupling the P type thermoelectric
semiconductor elements and the N type thermoelectric semiconductor
elements with the electrical insulator so that end faces of the P
type thermoelectric semiconductor elements and N type
thermoelectric semiconductor elements are located on different
planes.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a heat exchanger, and more
particularly, to a heat exchanger including a thermoelectric module
(Peltier module) in which a plurality of P type thermoelectric
semiconductor elements and a plurality of N type thermoelectric
semiconductor elements are electrically connected in series by
electrodes and thermally arranged in parallel.
[0002] FIG. 11A shows the structure of a typical thermoelectric
module 50 that allows for mutual conversion of heat energy and
electrical energy. The thermoelectric module 50 includes a
plurality of P type thermoelectric semiconductor elements 51 and a
plurality of N type thermoelectric semiconductor elements 52. The P
type thermoelectric semiconductor elements 51 and the N type
thermoelectric semiconductor elements 52 are alternately arranged
on a two dimensional plane and electrically connected in series by
electrodes 53. When the thermoelectric module 50 is supplied with
DC current, heat is absorbed at one of upper and lower heat
exchanging surfaces of the thermoelectric module 50 and dissipated
at the other one of the heat exchanging surfaces. FIG. 11B shows a
heat exchanger 55 including the thermoelectric module 50. The upper
and lower electrodes 53 are coupled to ceramic insulative plates
54. This forms a sandwiching structure in which the P type
thermoelectric semiconductor elements 51, the N type thermoelectric
semiconductor elements 52, and the electrodes 53 are held between
the insulative plates 54. The heat exchanger 55 includes a fluid
passage 57. A temperature-controlled fluid 56 flows through the
fluid passage 57, which is formed at one heat exchanging side of
the thermoelectric module 50. The heat exchanger 55 further
includes a fluid passage 59. A temperature-controlling medium 58
(heating medium or cooling medium) for heating or cooling the
temperature-controlled fluid 56 flows through the fluid passage 59,
which is formed at the other heat exchanging side.
[0003] In the structure of the heat exchanger 55 shown in FIG. 11B,
the insulative plates 54 and the inner wall surfaces of the fluid
passages 57 and 59 are arranged between the electrodes 53 and the
temperature-controlled fluid 56 or between the electrodes 53 and
the temperature-controlling medium 58. This structure produces
thermal resistance that lowers the efficiency of heat transfer.
Further, the difference in the coefficient of thermal expansion
between the insulative plates 54 and the P type thermoelectric
semiconductor elements 51 and the difference in the coefficient of
thermal expansion between the insulative plate 54 and the N type
thermoelectric semiconductor elements 52 produces thermal stress
applied to the coupled portions and the semiconductor elements.
This lowers the durability of the coupled portions and the
semiconductor elements.
[0004] A heat exchanger using a thermoelectric module that has
satisfactory heat transfer efficiency and transfers heat with small
heat variations has been proposed. This structure does not use the
insulative plates 54, and the electrodes 53 on at least one of the
heat exchanging surfaces of the thermoelectric module 50 are in
direct contact with the fluid in the fluid passages 57 and 59 (for
example, refer to Japanese Laid-Open Patent Publication No.
11-68173). In the thermoelectric module 50 of this heat exchanger,
as shown in FIG. 12, an electrical insulator 60 is filled and
solidified in gaps formed between the P type thermoelectric
semiconductor elements 51 and the N type thermoelectric
semiconductor elements 52. The electrical insulator 60 provides for
insulation and increases the structural strength of the
thermoelectric module 50. There is no passage wall between the
lower fluid passage 59 and the thermoelectric module 50. The
thermoelectric module 50 itself forms the passage wall of the fluid
passage 59. Thus, the temperature-controlling medium 58 is in
direct contact with the electrical insulator 60 and the electrodes
53. The publication describes another structure in which there is
also no passage wall between the upper fluid passage 57 and the
thermoelectric module 50.
[0005] To improve the heat dissipation efficiency, a thermoelectric
conversion unit (heat exchanger) including heat dissipation side
electrodes having heat dissipation portions exposed in a
refrigerant passage has been proposed (Japanese Laid-Open Patent
Publication No. 2000-286459). As shown in FIG. 13, the heat
exchanger includes a refrigerant jacket 61 and a thermoelectric
module 62 (thermoelectric conversion unit). A refrigerant passage
63 is formed in the refrigerant jacket 61. In the thermoelectric
module 62, a heat absorption side electrode 64, an N type
thermoelectric semiconductor element 65, a heat dissipation side
electrode 66, and a P type thermoelectric semiconductor element 67
are electrically connected in this order to form a single unit. A
plurality of such units (three units in the drawing) are connected
in series.
[0006] The heat absorption side electrodes 64 are formed to be
planar and coupled to an insulative substrate 68. End faces of an N
type thermoelectric semiconductor element 65 and a P type
thermoelectric semiconductor element 67 are each electrically
coupled to each heat absorption side electrode 64. The heat
dissipation side electrodes 66 each have an extension 66a formed on
the surface opposite to the surface coupled to the corresponding N
type thermoelectric semiconductor element 65 and P type
thermoelectric semiconductor element 67. The extensions 66a, which
are coated by insulative layers, are inserted into holes formed at
predetermined intervals in the refrigerant jacket 61. This exposes
the extensions 66a in the refrigerant passage 63. In addition to
the heat dissipation side electrodes 66, the heat absorption side
electrodes 64 may also have extensions, which are inserted into
holes formed at predetermined intervals in the refrigerant jacket
61 and exposed in a refrigerant passage.
[0007] In the heat exchanger of Japanese Laid-Open Patent
Publication No. 11-68173, at least one of the heat transfer sides
of the thermoelectric module 50 does not have the insulative plate
54. Further, the electrodes 53 are in contact with the fluids
(temperature-controlled fluid 56 or temperature-controlling medium
58) in the fluid passages 57 and 59. This increases the heat
transfer efficiency in comparison to a structure including the
insulative plate 54. However, the heat exchange surface (heat
transfer surface) that comes into contact with fluid is
substantially planar and only includes shallow recesses between the
electrodes 53. This forms a boundary layer when fluid flows in
parallel with the heat exchange surface and greatly affects the
heat exchange capacity.
[0008] In the thermoelectric conversion unit of Japanese Laid-Open
Patent Publication No. 2000-286459, the extensions 66a of the heat
dissipation side electrodes 66 are exposed in the refrigerant
passage 63. Thus, the extensions 66a agitate the refrigerant
flowing through the refrigerant passage 63. The effect of the
turbulent flow increases the heat dissipating efficiency in
comparison with the structure of Japanese Laid-Open Patent
Publication No. 11-68173 of which the electrodes do not include
such extensions. However, in the structure of Japanese Laid-Open
Patent Publication No. 2000-286459, the number of holes formed in
the refrigerant jacket 61 must be the same as the number of the
heat dissipation side electrodes 66, and the holes receiving the
extensions 66a must be sealed. This increases the burden on
manufacturing and raises the manufacturing cost. Further, depending
on the state of the seal, the force of the refrigerant applied to
the extensions 66a may act on the coupled portions between the heat
dissipation side electrodes 66 and the N type thermoelectric
semiconductor elements 65 and on the coupled portions between the
heat dissipation side electrodes 66 and the P type thermoelectric
semiconductor elements 67. This lowers durability.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide a heat
exchanger that performs heat exchange efficiently and includes a
plurality of P type thermoelectric semiconductor elements and a
plurality of N type thermoelectric semiconductor elements that are
electrically connected in series and thermally arranged in
parallel.
[0010] One aspect of the present invention is a heat exchanger
including a thermoelectric module. Heat exchange is performed
between a first fluid flowing through a first fluid passage
arranged at a heat dissipation side of the thermoelectric module
and a second fluid flowing through a second fluid passage arranged
at a heat absorption side of the thermoelectric module. The
thermoelectric module includes a plurality of P type thermoelectric
semiconductor elements and a plurality of N type thermoelectric
semiconductor elements that are thermally arranged in parallel.
Heat dissipation side electrodes formed by planar plates and heat
absorption side electrodes formed by planar plates electrically
connect in series the P type thermoelectric semiconductor elements
and the N type thermoelectric semiconductor elements. An electrical
insulator couples the P type thermoelectric semiconductor elements
and the N type thermoelectric semiconductor elements so as to
impede fluid movement between the first fluid passage and the
second fluid passage. The heat dissipation side electrodes are
exposed in the first fluid passage and the heat absorption side
electrodes are exposed in the second fluid passage. At least the
heat dissipation side of the thermoelectric module includes valleys
and ridges with the heat dissipation side electrodes being free
from projections.
[0011] Other aspects and advantages of the present invention will
become apparent from the following description, taken in
conjunction with the accompanying drawings, illustrating by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention, together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings in which:
[0013] FIG. 1 is a schematic cross-sectional view showing a heat
exchanger according to a first embodiment of the present
invention;
[0014] FIG. 2 is a schematic perspective view showing a
thermoelectric module of FIG. 1 in a state in which an electrical
insulator is partially removed from the thermoelectric module;
[0015] FIG. 3A is a plan view showing a thermoelectric module of
FIG. 1 in a state in which electrodes are removed from the
thermoelectric module;
[0016] FIG. 3B is a cross-sectional diagram taken along line 3B-3B
in FIG. 3A;
[0017] FIG. 4 is a schematic cross-sectional view showing a state
in which thermoelectric semiconductor elements are arranged in a
lower mold;
[0018] FIG. 5 is a schematic cross-sectional diagram showing a
state in which resin is filled in a mold to form the electrical
insulator;
[0019] FIG. 6 is a schematic cross-sectional view showing a heat
exchanger according to a second embodiment of the present
invention;
[0020] FIG. 7 is a schematic perspective view showing a
thermoelectric module of FIG. 6 in a state in which an electrical
insulator is partially removed from the thermoelectric module;
[0021] FIG. 8A is a schematic cross-sectional view showing a heat
exchanger according to a third embodiment of the present
invention;
[0022] FIG. 8B is a schematic perspective view showing a
thermoelectric module of FIG. 8A in a state in which an electrical
insulator is partially removed from the thermoelectric module;
[0023] FIG. 9A is a schematic cross-sectional view showing a heat
exchanger according to a fourth embodiment of the present
invention;
[0024] FIG. 9B is an enlarged cross-sectional view showing part of
the thermoelectric module of FIG. 9A;
[0025] FIG. 9C is a plan view showing the thermoelectric module of
FIG. 9A;
[0026] FIGS. 10A and 10B are schematic perspective views showing
projections in a further embodiment;
[0027] FIG. 11A is a schematic diagram showing a prior art
thermoelectric module;
[0028] FIG. 11B is a schematic cross-sectional diagram showing a
heat exchanger using the thermoelectric module of FIG. 11A;
[0029] FIG. 12 is a schematic cross-sectional diagram showing
another prior art heat exchanger; and
[0030] FIG. 13 is a schematic cross-sectional diagram showing a
further prior art heat exchanger.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] A first embodiment of the present invention will now be
discussed with reference to FIGS. 1 to 5.
[0032] Referring to FIG. 1, a heat exchanger includes a
thermoelectric module 11. A first fluid 12 flows through a first
fluid passage 13, which is located at a heat dissipation side
(upper side as viewed in FIG. 1) of the thermoelectric module 11. A
second fluid 14 flows through a second fluid passage 15, which is
located at a heat absorption side (lower side as viewed in FIG. 1)
of the thermoelectric module 11.
[0033] The thermoelectric module 11 includes a plurality of P type
thermoelectric semiconductor elements 16 and a plurality of N type
thermoelectric semiconductor elements 17. The P type thermoelectric
semiconductor elements 16 and the N type thermoelectric
semiconductor elements 17 are electrically connected in series by
electrodes and thermally arranged in parallel. The phrase
"thermally arranged in parallel" refers to a state in which the P
type thermoelectric semiconductor elements 16 and N type
thermoelectric semiconductor elements 17 have heat dissipation side
surfaces that are all arranged on one side of the thermoelectric
module 11 and heat absorption side surfaces that are all arranged
on the other side of the thermoelectric module 11.
[0034] The first fluid passage 13 and the second fluid passage 15
are formed to be flat at least at portions that receive the
thermoelectric module 11. Openings 13a and 15a, which face toward
each other, are respectively formed in the first fluid passage 13
and the second fluid passage 15 to receive the thermoelectric
module 11. The thermoelectric module 11 includes heat dissipation
side electrodes 18 and heat absorption side electrodes 19. In a
state in which the heat dissipation side electrodes 18 are exposed
in the first fluid passage 13 and the heat absorption side
electrodes 19 are exposed in the second fluid passage 15, the
thermoelectric module 11 is arranged between the first fluid
passage 13 and second fluid passage 15, which are spaced from each
other by spacers 20. In the thermoelectric module 11, an electrical
insulator 21, which is formed from a polymeric material, couples
the P type thermoelectric semiconductor elements 16 and the N type
thermoelectric semiconductor elements 17. This impedes the movement
of fluid between the first fluid passage 13 and the second fluid
passage 15. A thermosetting resin, a thermoplastic resin, or rubber
may be used as the polymeric material. However, the preferable
material for the electrical insulator 21 is thermosetting resin
since thermosetting resin functions to increase the structural
strength of the thermoelectric module 11 in addition to insulating
the P type thermoelectric semiconductor elements 16 from the N type
thermoelectric semiconductor elements 17.
[0035] As shown in FIG. 3A, the P type thermoelectric semiconductor
elements 16 and the N type thermoelectric semiconductor elements 17
are arranged in a plurality of lines so as to form a matrix array
in which the P type thermoelectric semiconductor elements 16 are
arranged adjacent to the N type thermoelectric semiconductor
elements 17. The P type thermoelectric semiconductor elements 16
and N type thermoelectric semiconductor elements 17 are each formed
to have the shape of a square pillar and each have metalized
surfaces that are coupled to the electrodes 18 and 19. For example,
the P type thermoelectric semiconductor elements 16 and N type
thermoelectric semiconductor elements 17 may be soldered and
electrically coupled to the electrodes 18 and 19. The electrodes 18
and 19 are each formed by a metal planar plate having a length
allowing for the coupling of one set of a P type thermoelectric
semiconductor element 16 and an N type thermoelectric semiconductor
element 17. Further, the electrodes 18 and 19 each have an
electrode surface, which is free from projections and which forms a
main heat exchange surface of the thermoelectric module 11.
[0036] The electrical insulator 21 includes a plurality of
projections 21a, which are formed in parts of the heat dissipation
side and heat absorption side of the thermoelectric module 11. The
projections 21a each project further from the electrodes 18 and 19
into the first fluid passage 13 or second fluid passage 15. In
other words, the heat dissipation side and heat absorption side of
the thermoelectric module 11 include valleys and ridges with the
electrodes 18 and 19 being free from projections. As shown in FIGS.
2 and 3(a), the projections 21a formed at the heat dissipation side
have the shape of a parallelepiped, which extends in a direction
perpendicular to the direction the first fluid 12 flows in the
first fluid passage 13. The projections 21a are arranged in a
zigzagged manner. The projections 21a formed at the heat absorption
side are arranged in the same manner.
[0037] The electrodes 18 arranged at the heat dissipation side are
all connected to the P type thermoelectric semiconductor elements
16 and N type thermoelectric semiconductor elements 17, which
extend parallel to the direction the projections 21a extend. Thus,
the electrodes 18 do not interfere with the projections 21a
regardless of the locations of the projections 21a. The phrase "the
direction the projections 21a extend" refer to the widthwise
direction of the fluid passage 15, that is, the direction
perpendicular to the direction fluid flows. Among the electrodes 19
arranged at the heat absorption side, the electrodes 19 at the two
sides of the thermoelectric module 11 with respect to the direction
the projections 21a extend are arranged in a direction
perpendicular to the direction the projections 21a extend, that is,
in the flow direction of the fluid 14. Thus, the projections 21a
are formed at positions that do not interfere with the electrodes
19.
[0038] The manufacturing of the thermoelectric module 11 will now
be described. Insert molding is performed to form a thermoelectric
element unit that couples the P type thermoelectric semiconductor
elements 16 and N type thermoelectric semiconductor elements 17 to
the electrical insulator 21. Then, the end faces of the P type
thermoelectric semiconductor elements 16 and N type thermoelectric
semiconductor elements 17 are soldered to the electrodes 18 and 19
to manufacture the thermoelectric module 11. When performing insert
molding, as shown in FIG. 4, the P type thermoelectric
semiconductor elements 16 and the N type thermoelectric
semiconductor elements 17 are positioned and arranged in a lower
mold 22a. Then, as shown in FIG. 5, after an upper mold 22b closes
the lower mold 22a, an unhardened thermosetting resin is charged
into the lower and upper molds 22a and 22b and heated for
hardening. This forms the thermoelectric element unit. The
positioning of the P type thermoelectric semiconductor elements 16
and the N type thermoelectric semiconductor elements 17 is
performed by arranging one end of each of the P type thermoelectric
semiconductor elements 16 and the N type thermoelectric
semiconductor elements 17 in shallow recesses formed in the lower
mold 22a.
[0039] The operation of the heat exchanger will now be described.
The heat exchanger is used by applying DC voltage to the electrodes
18 and 19 so that the side of the thermoelectric module 11 facing
toward the first fluid passage 13 serves as the heat dissipation
side and the side facing toward the second fluid passage 15 serves
as the heat absorption side. Further, the first fluid 12 and the
second fluid 14 flow in the same direction in the first fluid
passage 13 and the second fluid passage 15, for example, from the
left toward the right as viewed in FIG. 1. The first fluid 12
circulates through a path that includes a cooling fan (not
shown).
[0040] When the thermoelectric module 11 is activated, the heat
absorption side electrodes 19 absorb heat from the second fluid 14,
and the heat dissipation side electrodes 18 dissipate heat to the
first fluid 12. That is, direct heat transfer is performed between
the electrodes 19 and the second fluid 14, and direct heat transfer
is performed between the electrodes 18 and the first fluid 12. When
fluid travels in a laminar flow, laminar flow boundary layers are
produced at the surfaces of the heat dissipation side electrode 18
and the heat absorption side electrodes 19 that serve as heat
exchange surfaces. An increase in the influence of the boundary
layer would decrease the heat exchange capacity. However, the
thermoelectric module 11 includes the projections 21a at the heat
dissipation side and heat absorption side so as to form valleys and
ridges. Thus, turbulent flows are produced in the first fluid 12
flowing through the first fluid passage 13 and the second fluid 14
flowing through the second fluid passage 15 at portions
corresponding to the thermoelectric module 11. The turbulent flows
function to reduce the influence of the boundary layer at the heat
exchange surface so that heat exchange is efficiently performed at
the heat dissipation side and heat absorption side.
[0041] The first embodiment has the advantages described below.
[0042] (1) The heat dissipation side electrodes 18 and the heat
absorption side electrodes 19 are respectively exposed in the first
fluid passage 13 and the second fluid passage 15. Thus, the
electrodes 18 and 19 are in direct contact with fluid (i.e., the
first fluid 12 or the second fluid 14), and heat exchange is
performed efficiently.
[0043] (2) The electrical insulator 21, which is formed from a
polymeric material, couples the P type thermoelectric semiconductor
elements 16 and the N type thermoelectric semiconductor elements
17. This impedes the movement of fluid between the first fluid
passage 13 and the second fluid passage 15. The electrodes 18 and
19 are formed by planar plates, and the heat dissipation side and
heat absorption side of the thermoelectric module 11 include
valleys and ridges. Accordingly, the turbulent flow produced by the
flow of fluid functions to reduce the influence of a boundary layer
at the heat exchange surface so that heat exchange is efficiently
performed at the heat dissipation side and heat absorption side.
Thus, the heat exchanger efficiently performs heat exchange.
[0044] (3) The valleys and ridges at the heat dissipation side of
the thermoelectric module 11 are formed by the projections 21a,
which project from parts of the electrical insulator 21. The
projections 21a project further from the electrodes 18 into the
first fluid passage 13. The valleys and ridges at the heat
absorption side of the thermoelectric module 11 are formed by the
projections 21a, which project from parts of the electrical
insulator 21. The projections 21a project further from the
electrodes 19 into the second fluid passage 15. In this manner,
valleys and ridges are formed in the heat dissipation side and heat
absorption side without forming projections (extensions) on the
electrodes 18 and 19. This simplifies the structure of the
electrodes 18 and 19, which, in turn, simplifies the structure of
the heat exchanger. Further, unlike when forming projections on the
electrodes 18 and 19, the portions at which the electrodes 18 and
19 are coupled to the P type thermoelectric semiconductor elements
16 and the N type thermoelectric semiconductor elements 17 are free
from the force of fluid that is applied to the projections. This
prevents the durability of such coupled portions from being
lowered, which, in turn, prevents the durability of the heat
exchanger from being lowered. Moreover, in comparison with a
structure that forms projections on electrodes, the manufacturing
costs may be reduced.
[0045] (4) When using a mold to form the thermoelectric element
unit by coupling the P type thermoelectric semiconductor elements
16 and the N type thermoelectric semiconductor elements 17 with the
electrical insulator 21 while ensuring electric insulation, the
portions that become the projections 21a are elongated from the
other portions of the electrical insulator 21. This facilitates
manufacturing in comparison to a structure that couples the
projections 21a, or extensions, in a subsequent process.
[0046] (5) The electrodes 18 and 19 are formed by metal planar
plates. Further, the connection positions of the electrodes 18 and
19 and the formation positions of the projections 21a are set so
that interference does not occur between the electrodes 18 and 19
and the projections 21a. This simplifies the structures and
formation of the electrodes 18 and 19.
[0047] A second embodiment will now be discussed with reference to
FIGS. 6 and 7. This embodiment differs from the first embodiment in
the shape of the projections 21a, which form the valleys and ridges
in the heat dissipation side and heat absorption side of the
thermoelectric module 11. To avoid redundancy, like or same
reference numerals are given to those components that are basically
the same as the corresponding components of the first embodiment.
Such components will now be described in detail.
[0048] As shown in FIG. 6, the projections 21a are formed to be in
contact with the inner wall surface of the first fluid passage 13
and the second fluid passage 15. As shown in FIG. 7, the heat
dissipation side projections 21a are projected to form a plurality
of (three in this embodiment) flow paths 13b in the first fluid
passage 13. The arrangement of the heat dissipation side electrodes
18 and the heat absorption side electrodes 19 is the same as the
first embodiment. Thus, the heat absorption side projections 21a
are projected to form a plurality of (two in this embodiment) flow
paths 15b in the second fluid passage 15 so that the projections
21a do not interfere with the electrodes 19. Each flow path 15b is
1.5 times longer than each flow path 13b.
[0049] In the heat exchanger of this embodiment, as the first fluid
12 that flows through the first fluid passage 13 passes through the
portion corresponding to the thermoelectric module 11, the first
fluid 12 is divided into three when entering the three flow paths
13b. Each flow path 13b is formed to meander and does not extend
straight. Thus, the first fluid 12 produces a turbulent flow in
each flow path 13b. Further, the second fluid 14 that flows through
the second fluid passage 15 is divided into two when entering the
two flow paths 15b. The second fluid 14 produces a turbulent flow
in each flow path 15b. Further, whenever the second fluid 14
meanders back and forth in the flow path 15b, the second fluid 14
travels over a distance that is 1.5 times longer than the
meandering distance of the flow paths 13b. As a result, the
turbulent flow functions to reduce the influence of a boundary
layer at the heat exchange surface, and heat exchange is
efficiently performed at the heat dissipation side and heat
absorption side.
[0050] Accordingly, in addition to advantages (1) to (5) of the
first embodiment, the second embodiment has the advantages
described below.
[0051] (6) The first fluid 12 in the first fluid passage 13 and the
second fluid 14 in the second fluid passage 15 flow along the flow
paths 13b and 15b, which are formed by part of the electrical
insulator 21. This facilitates calculation of the heat exchange
efficiency for each of the electrodes 18 and 19.
[0052] (7) The thermoelectric module 11 is supported between the
first fluid passage 13 and the second fluid passage 15 in a state
in which the projections 21a are in contact with the inner wall
surfaces of the first and second fluid passages 13 and 15. Thus,
the projections 21a have distal ends that abut against the inner
wall surface of the first fluid passage 13 and the inner wall
surface of the second fluid passage 15. This allows for elimination
of the spacer 20.
[0053] A third embodiment will now be discussed with reference to
FIGS. 8A and 8B. This embodiment differs from the first embodiment
in that the P type thermoelectric semiconductor elements 16 and the
N type thermoelectric semiconductor elements 17 have end faces that
are not arranged along the same plane. To avoid redundancy, like or
same reference numerals are given to those components that are
basically the same as the corresponding components of the first
embodiment. Such components will now be described in detail.
[0054] As shown in FIGS. 8A and 8B, the P type thermoelectric
semiconductor elements 16 and the N type thermoelectric
semiconductor elements 17 are all formed to have the same size.
However, the P type thermoelectric semiconductor elements 16 and
the N type thermoelectric semiconductor elements 17 have end faces
arranged in rows, the locations of which are alternately varied. In
this state, the electrical insulator 21 couples the P type
thermoelectric semiconductor elements 16 and the N type
thermoelectric semiconductor elements 17. Accordingly, the
thermoelectric module 11 in its entirety has valleys and ridges
formed in both of the heat dissipation and heat absorption sides.
Further, as shown in FIG. 8A, the thermoelectric module 11 is
arranged between the first fluid passage 13 and the second fluid
passage 15 in a state in which projections 23 extend in a direction
perpendicular to the direction the first fluid 12 and second fluid
14 flow (from the left toward the right in FIG. 8A). The electrodes
18 connected to the P type thermoelectric semiconductor elements 16
and the N type thermoelectric semiconductor elements 17 at the heat
dissipation side of the thermoelectric module 11 all extend
parallel to the extending direction the projections 23. Thus, the
electrodes 18 are formed to be planar. However, among the
electrodes 19 coupled to the P type thermoelectric semiconductor
elements 16 and the N type thermoelectric semiconductor elements 17
at the heat absorption side, the electrodes 19 located at the two
sides of the thermoelectric module 11 with respect to the direction
the projections 23 extend are each connected to a P type
thermoelectric semiconductor element 16 that serves as a projection
23 and an N type thermoelectric semiconductor element 17 that does
not serve as one. Thus, such an electrode 19 is bent into the shape
of a crank to allow for the connection of the electrode 19.
[0055] In this embodiment, valleys and ridges are also formed at
portions in the heat dissipation side and heat absorption side of
the thermoelectric module 11. Thus, turbulent flows are produced in
the first fluid 12, which flows through the first fluid passage 13,
and the second fluid 14, which flows through the second fluid
passage 15, at portions corresponding to the thermoelectric module
11. The electrical insulator 21 couples the P type thermoelectric
semiconductor elements 16 and the N type thermoelectric
semiconductor elements 17 by performing insert molding with a mold
having a cavity shaped differently from that of the first
embodiment. Further, the electrodes 19 that are bent into the shape
of a crank are easily manufactured by pressing a metal plate.
[0056] Accordingly, in addition to advantages (1) and (2) of the
first embodiment, this embodiment has the advantages described
below.
[0057] (8) The valleys and ridges at the heat dissipation side of
the thermoelectric module 11 are formed by coupling the P type
thermoelectric semiconductor elements 16 and the N type
thermoelectric semiconductor elements 17 with the electrical
insulator 21 so that their end faces are arranged on different
planes. Accordingly, the thermoelectric module 11 is easily
manufactured by varying the locations of the P type thermoelectric
semiconductor elements 16 and N type thermoelectric semiconductor
elements 17 that have the same size and using the electrodes 19
that are formed by bending planar plates into a crank shape.
[0058] (9) The projections 23 are formed to extend entirely in the
widthwise direction of the first fluid passage 13 and the second
fluid passage 15 (i.e., the direction perpendicular to the
direction in which fluid flows). Thus, there is a tendency for a
turbulent flow to be easily produced along the entire heat exchange
surface.
[0059] A fourth embodiment will now be discussed with reference to
FIGS. 9A to 9C. This embodiment differs from each of the
embodiments discussed above in that there are a plurality of
thermoelectric modules. To avoid redundancy, like or same reference
numerals are given to those components that are basically the same
as the corresponding components of the first embodiment. Such
components will now be described in detail.
[0060] As shown in FIG. 9A, a heat exchanger includes a plurality
of (four in this embodiment) thermoelectric modules 11 arranged
between the first fluid passage 13 and the second fluid passage 15.
In the embodiments discussed above, each thermoelectric module 11
includes a total of thirty-six P type thermoelectric semiconductor
elements 16 and N type thermoelectric semiconductor elements 17. In
this embodiment, each thermoelectric module 11 includes a total of
sixteen P type thermoelectric semiconductor elements 16 and N type
thermoelectric semiconductor elements 17. Thus, each thermoelectric
module 11 includes less semiconductor elements than that of the
first embodiment. However, the total number of the P type
thermoelectric semiconductor elements 16 and N type thermoelectric
semiconductor elements 17 in the four thermoelectric modules 11 is
sixty-four. Thus, the total number of the semiconductor elements is
greater than that of the first embodiment.
[0061] As shown in FIGS. 9B and 9C, a packing 24 is formed
integrally with the periphery of each thermoelectric module 11.
Further, as shown in FIG. 9B, the packing 24 holds the
corresponding thermoelectric module 11 between the first fluid
passage 13 and the second fluid passage 15. Projections 21a
projecting into the first fluid passage 13 and the second fluid
passage 15 are formed at the heat dissipation side and heat
absorption side of each thermoelectric module 11. The
thermoelectric modules 11 are connected in series by electrode
terminals (not shown). Further, the thermoelectric modules 11 are
all simultaneously supplied with the same current.
[0062] In addition to advantages (1) to (5) of the first
embodiment, this embodiment has the advantages described below.
[0063] (10) Each thermoelectric module 11 is independently attached
by the corresponding packing 24 to the first fluid passage 13 and
the second fluid passage 15 to form the entire heat exchanger. When
the heat exchanger requires a large number of the P type
thermoelectric semiconductor elements 16 and the N type
thermoelectric semiconductor elements 17, the heat exchanger may
increase the number of thermoelectric modules 11 accordingly, with
each thermoelectric module 11 having a relatively small number of
the P type thermoelectric semiconductor elements 16 and the N type
thermoelectric semiconductor elements 17. This lowers the
manufacturing cost of the thermoelectric module 11, which, in turn,
lowers the manufacturing cost of the heat exchanger. Further, when
one of the thermoelectric modules 11 becomes defective, only the
defective thermoelectric module 11 needs to be replaced. This
facilitates maintenance. When the heat exchanger fails to function
normally, the defective thermoelectric module 11 may be located by
detecting the voltage or current between the terminals of each
thermoelectric module 11.
[0064] It should be apparent to those skilled in the art that the
present invention may be embodied in many other specific forms
without departing from the spirit or scope of the invention.
Particularly, it should be understood that the present invention
may be embodied in the following forms.
[0065] The shape of the projections 21a is not limited to a
parallelepiped and may be a triangular solid as shown in FIG. 10A
or saw-toothed as shown in FIG. 10B. Further, the length of the
projections 21a may be varied. Alternatively, projections 21a of
different shapes and lengths may be used in combination. The
shapes, lengths, and the like of the projections 21a that allow for
efficient heat exchange vary in accordance with the physical
properties (e.g., viscosity) or flow velocity of the first fluid 12
and second fluid 14. It is thus preferable that experiments be
conducted to obtain the shape, length, and the like that allows for
a suitable turbulent flow to be easily produced when setting the
shape, length, and location of the projections 21a.
[0066] The shape and length of the first fluid passage 13 and the
second fluid passage 15 varies in accordance with the amount of
heat generated by the thermoelectric module 11 and the physical
properties (e.g., viscosity) and flow velocity of the refrigerant.
It is thus preferable that experiments be conducted to obtain the
shape, length, and the like that allows for a suitable turbulent
flow to be easily produced when setting the shape, length, and
location of the first and second fluid passages 13 and 15.
[0067] The thermoelectric module 11 is not limited to a structure
in which the valleys and ridges are arranged on both of the heat
dissipation side and the heat absorption side. It is only required
that the valleys and ridges be arranged on at least the heat
dissipation side. The amount of heat generated at the heat
dissipation side is approximately four times greater than the heat
absorbed at the heat absorption side. This allows for the
requirements of the heat exchanger to be easily fulfilled by
efficiently exchanging heat at the heat dissipation side.
[0068] The first fluid 12 and the second fluid 14 are not limited
to an insulative liquid and may be an insulative gas (e.g., air) or
a conductive liquid. When using a conductive liquid, an insulative
coating must be applied to the surfaces of the electrodes 18 and 19
that contact the first fluid 12 and the second fluid 14.
[0069] The projections 21a do not have to be formed by extending
parts of the electrical insulators 21 and may be formed by adhering
discrete components to the electrical insulator 21. In this case,
after connecting the electrodes 18 and 19 to the P type
thermoelectric semiconductor elements 16 and the N type
thermoelectric semiconductor elements 17, the projections 21a may
be coupled to the electrical insulator 21 so as to intersect the
electrodes 18 and 19. This allows for the arrangement of the
projections 21a and the electrodes 18 and 19 in an intersecting
state without any problems and thereby increases the degree of
freedom for the locations of the projections 21a.
[0070] In the first fluid passage 13 and the second fluid passage
15, the first fluid 12 and the second fluid 14 do not have to flow
in the same direction. The first fluid 12 in the first fluid
passage 13 and the second fluid 14 in the second fluid passage 15
may flow in opposite directions (opposed flow).
[0071] In the third embodiment, the valleys and ridges on the heat
dissipation side and heat absorption side of the thermoelectric
module 11 are provided without arranging the end faces of the P
type thermoelectric semiconductor elements 16 and N type
thermoelectric semiconductor elements 17 on the same plane.
Further, the end faces of the P type thermoelectric semiconductor
elements 16 and N type thermoelectric semiconductor elements 17 are
arranged in rows, the locations of which are alternately varied.
However, the present invention is not limited to such a structure.
For example, the locations of just one half of the end faces in
each row may be alternately varied. Alternatively, the locations of
every single end face or every two end faces may be alternately
varied.
[0072] In the third embodiment, the electrical insulator 21 that
couples the P type thermoelectric semiconductor elements 16 and the
N type thermoelectric semiconductor elements 17 do not necessarily
have to be formed at locations corresponding to the projections
23.
[0073] When arranging the valleys and ridges on the heat
dissipation side and heat absorption side of the thermoelectric
module 11 without arranging the end faces of the P type
thermoelectric semiconductor elements 16 and N type thermoelectric
semiconductor elements 17 on the same plane, P type thermoelectric
semiconductor elements 16 of two different lengths and N type
thermoelectric semiconductor elements 17 of two different lengths
may be used.
[0074] The matrix array of the P type thermoelectric semiconductor
elements 16 and the N type thermoelectric semiconductor elements 17
that form the thermoelectric module 11 do not have to include the
same number of rows and columns.
[0075] The P type thermoelectric semiconductor elements 16 and the
N type thermoelectric semiconductor elements 17 do not have to have
the shape of a square pillar and may have the shape of another type
of a polygonal pillar or a cylindrical pillar.
[0076] In addition to the fourth embodiment, the other embodiments
may also include the packing 24 that is formed around the
thermoelectric module 11 and attaches the thermoelectric module 11
between the first fluid passage 13 and the second fluid passage
15.
[0077] The present examples and embodiments are to be considered as
illustrative and not restrictive, and the invention is not to be
limited to the details given herein, but may be modified within the
scope and equivalence of the appended claims.
* * * * *