US3071932A

US3071932A - Heat exchange system for thermoelectric generators

Info

Publication number: US3071932A
Application number: US102514A
Authority: US
Inventors: Poganski Siegfried; Hoffmann Johannes
Original assignee: Licentia Patent Verwaltungs GmbH
Current assignee: Licentia Patent Verwaltungs GmbH
Priority date: 1960-04-13
Filing date: 1961-04-12
Publication date: 1963-01-08
Anticipated expiration: 1980-01-08

Description

Jan. 8, 1963 s. POGANSKI ETAL 3,071,932

HEAT EXCHANGE SYSTEM FOR THERMO-ELECTRIC GENERATORS Filed April 12, 1961 N I .1 k

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lllllll/l/I/A .7 n v e n10 r5 .S/EGFR/ED POGANSK/ JOHANNES HOFFMAN/V United States Patent Ofifice 3,li7l,932 Patented Jan. 8, 1963 3,071,932 HEAT EXCHANGE SYETEM FOR THERMG- ELEQTREC GENERATORS Siegfried Pogansioi, Langeu, Hesse, and Johannes Holimanu, Frankfurt am Main, Germany, assignors to Lieentia Patent-Verwaltuugs-G.m.h.H., Frankfurt am Main, Germany Filed Apr. 12, 196i, Ser. No. 1i2,51d Iiaims priority, application Germany Apr. i3, 196% 15 Claims, (Cl. 62-3) The present invention relates to a thermo-electric generator; more particularly, this invention relates to an im provement in the heat exchange system of a thermo-electric generator.

The recent development of suitable materials for the members of a thermo-couple, brought about the employment of the Peltier effect as an efficient mode of cooling or heating. The Peltier effect is the known inverse phenomenon of the generation of an electric current by differently heatin" the two soldering spot or junctions between pairs of dissimilar thermo-electric materials.

For economically using the Peltier effect, it is necessary to provide for a good heat exchange between the effective thermo-couple junction and a cooling or heat exchange medium. Known devices for example, employ tubes on which is mounted one or more thermo-couples, and the heat exchange is carried out through the walls of such tube. This is inherently ineificient because the inevitable strong temperature gradient in the tube wall reduces the eifective heating or cooling temperature. According to other solutions, the heat exchanger of the thermo-couple is provided with a bore being passed through by the heat exchange medium. This is also disadvantageous, because a very large expenditure is required with regard to sealing material and construction work.

It is a primary object of the present invention to provide for a new and improved heat exchange system for thermo-electric generators, overcoming the deficiencies of the known devices.

' It is another object of the present invention to provide a novel structure with regard to the heat exchange device employed in Peltier heating-cooling systems.

It is'a feature of the present invention to provide a uniform tubular conduit upon which is mounted one or more thenno-couples, the effective junctions thereof having a member protruding into the conduit, but each member being electrically insulated from the others. These members are thus positioned across the path of the common cooling medium passing through the conduit which may be a rigid pipe or a flexible hose.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and feature of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawing in which:

FIGURE 1 illustrates a cross-sectional view of a heat exchange system employing the principles of the present invention,

FIGURE 2 is a sectional view of the device shown in FIG. 1 taken in the plane marked II-II therein,

FIGURE 3 illustrates in a cross-sectional view another embodiment of the present invention,

FIGURE 4 illustrates a section taken along IV-IV in FIG. 3, and

FIGURE 5 is a cross-sectional view of a simplification of the device shown in FIGS. 3 and 4.

Turning now to the detailed description of the drawings, in FIGS. 1 and 2 there is first shown a chute, pipe or tubular conduit 1 made of an electrically insulating material and being passed through by a cooling medium in a direction positioned in the plane of the drawing in FIG. 1 and perpendicular thereto in FIG. 2.

There is a slot shaped opening in pipe 1 and a metallic tongue 2 passes therethrough so as to be positioned in and across the path of the cooling medium. Tongue 2 is a member of the heat exchanger 3 and preferably is integral therewith. Thus, there is a good heat conductive relationship present as between tongue 2 and the main part of heat exchanger 3. There are provided two thermo-couple members 4 and 5 of diiferent types of thermo-conductivity. Heat exchangers 6 and 7 are secured to elements 4 and 5, respectively. Elements 3 to '7 together form a thermo-couple, as the primary element of a thermo-electric generator.

Heat exchangers 6 and 7 are provided with aligned bores 8 and 9, respectively, used for input or output of heat. Elements 6 and 7 also serve as electrical contact terminals for the electric current fed thereto, and the heat exchanger 3 defines the effective junction of members 4 and 5.

Tongue 2 is provided with an insulating layer, 2' such as a lacquer or the like, electrically insulating tongue 2 completely from the cooling medium passing through pipe 1. This is an important feature if pipe 1 is provided with a plurality of electrically interconnected thermocouple elements as described, each one operating at a different level of electrical potential.

The overall electrical resistance of the thermo-couples used as Poitier-coolers or heaters is very low indeed, even including all additional electrical conductors employed. Thus, a leakage path through the cooling medium might not be a serious deficiency. Nevertheless, in case the number of thermo-elements employed is large, such leakage of current might reduce the efiiciency of the cooling system to an extent which cannot be neglected. The insulating layer 2 is to prevent this leakage current, and it covers completely the surface of member 2 protruding into pipe 1.

It was said above that there is a voltage present between neighborhoring thermo-couple junctions influenced by the cooling medium; but this voltage is a small one. Thus, the layer 2 needs to be only very thin, but of course, thick enough to prevent any break-through. This feature, in turn, is of advantage because layer 2' must not impede the heat exchange between tongue 2 and the cooling medium in pipe 1. In addition, of course, one will select the layer 2' of a material of good heat conductivity.

The device as shown can operate as a Peltier cooler as well as a heater; the respective mode of operation depends upon the direction of the electric current through the thermo-couple, and whether junction 3 is a hot junction or a cold junction. The flow of heat between the medium and the various tongues such as 2 will then have a direction accordingly.

It is not essential, that the pipe 1 be completely made of an electrically insulating material. It can be made of a conductive material, but then a layer of insulating material must be interposed between such pipe and elements 2 and 3.

The invention is susceptible of embodiments in which the heatexchange member protruding into the pipe serves also as a securing frame or as a supporting structure of the pipe and the heat exchanger as a whole. It is possible to provide structure so that the heat exchanger together with the thermo-couple or couples supports the pipe or vice versa. The following figures illustrate such features.

In FIGS. 3 and 4 there is shown a rubber or a tombac hose 10 having a pair of openings 11 and 11', the opening of each pair being aligned and having a common axis disposed transversely to the center axis of' the hose; the pairs of openings are disposed along the latter axis.

o Each-pair receives a cylindircal heat exchanger 30, thus extending also transversely with respect to the axis of hose 10. Each heat exchanger has a threaded bore receiving a screw 13 fastening the heat exchanger to the hose whereby a washer 14 is disposed between the head of screw 13 and hose 1! for sealing the interior thereof from the outside. A ring 15 receives heat exchanger 30 and serves as a spacer between opposing walls of hose 10 so as to prevent any squeezing thereof. There are provided circumferentially disposed and radially directed bores in ring 15 permitting passage of a cooling medium as close as feasible to heat exchanger 30.

A heat exchanger and conductor plate 12 connects heat and an electrically conductive member 12' to member 30. Each thermo-couple is completed by thermo

active members

16 and 17 as well as

outer heat exchangers

13 and 19 having bores for passage of an outer heat exchange or cooling medium. Plate member 12' defines the effective junction being in heat exchange with the medium passing through hose 10. There may be provided another washer, disposed between hose 10 and plate 12.

As stated above, the several therrno-elements such as the two shown in FIG. 3 are disposed so as to be positioned in parallel to the axis of hose it). This is not an essential feature and other configurations are possible. For example, the thermo-elements can be disposed along a helical line around hose 19. In this instance FIG. 3 is to be understood to illustrate a section where the section plane illustrated at left hand portion and the section plane of the right hand portion do not coincide but are azimuthally displaced with respect to the axis of hose It). The device shown in FIG. 3 and FIG. 4 can be understood that the hose llt) rests on the plates 12, or that the thermo-cOuples are supported thereon.

A simplification of the mutual supporting structure of hose and heat exchanger as shown in FIGS. 3 and 4, is shown in FIG. 5.

A hose 24 is assumed to have sufiicient rigidity so as to provide sufiicient sealing and supporting structure without washers and spacers such as shown in the preceding figures.

A heat exchanger 21 is provided with an extension identified as member 2%} having two

grooves

22 and 23 receiving the walls of aligned bores in hose 24. This combines sealing and spacing. The thermo-couple members 23 are connected to plate 21 so as to form a thermocouple similar to the one shown in FIGS. 1 and 2. In this embodiment, the hose 24 will retain its circular cross-section.

It will be observed, that the heat exchange between the elements protruding into the pipe or hose as shown in the various examples can be improved, if such elements are provided with additional tongues, fins, etc. increasing the active or available surface for interaction with the cooling medium. This is also shown by way of example in FIG 5, illustrating disks 25 and 26 mounted on member 24 and offering extended heat exchange surfaces in the direction of fiow of the cooling medium (arrow 27). The invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departments from the spirit and scope of the invention are intended to be covered by the following claims.

We claim:

1. Thermo-electric device operating with the Peltier effect comprising: a tubular element for a heat exchange medium passing therethrough and having at least one aperture the walls of which are electrically insulating; at least one thermo-couple disposed outside of said tubular element and including means defining a thermo-couple junction being disposed also outside of said tubular element; and a heat exchange member electrically and heat conductively connected to said means defining said junction and protruding through said aperture into the interior of said tubular element while extending substantially across the axis thereof.

2. Thermo-electric device operating with the Peltier effect comprising: a tubular element made of electrically insulating material for passage of a heat exchange medium passing therethrough; thermo-couple members of dissimilar thermo-electric conductivity disposed outside of said tubular element; connecting means secured to said members so as to form a thermo-couple junction disposed also outside of said tubular element; and a heat exchange member electrically and heat conductively connected to said connecting means and protruding into the interior of said tubular element and extending substantially across the center axis thereof.

3. Thermo-electric device operating with the Peltier effect comprising: a tubular element for a heat exchange medium passing therethrough and having at least one aperture the walls of which are electrically insulating; at least one therrno-couple disposed outside of said tubular element and including means defining a thermo couple junction being also outside of said tubular element; and a heat exchange member electrically and heat conductively connected to said means defining said junction and protruding through said aperture into the interior of said tubular element substantially across the axis thereof, said member being covered with a layer of electrically insulating but thermally conductive material.

4. Thermo-electric device operating with the Peltier effect comprising: a flexible hose made of electrically insulating material for passage of a heat exchange medium therethrough; a thermo-couple disposed outside of said flexible hose and including a therrno-couple junction being also disposed outside of said flexible hose; and a heat exchange member electrically and heat conductively connected to said junction and protruding into the interior of said flexible hose substantially across the axis thereof.

5. Thermo-electric device operating with the Peltier effect comprising: a rubber hose for passage of a heat exchange medium therethrough; a thermo-couple disposed outside of said rubber hose; and a heat exchange member electrically and heat conductively connected to said junction and protruding into the interior of said rubber hose substantially across the axis thereof.

6. Thermo-electric device operating with the Peltier efiect comprising: a tubular element for a heat exchange medium passing therethrough and having at least one aperture the walls of which are electrically insulating; at least one thermo-couple being disposed outside of said tubular element and having a thermo-couple junction being disposed also outside of said tubular element; and a heat exchange member electrically and heat conductively connected to said junction and protruding through said aperture into the interior of said tubular element substantially across the axis thereof, said heat exchange member providing securing structure of mutual support of said tubular element and said thermo-couples.

7. Thermo-electric device operating with the Peltier effect comprising: a tubular element for a heat exchange medium passing therethrough and including electrically insulating means defining two openings aligned transversely with respect to its center axis; a thermo-couple having a junction disposed outside of said tubular element adjacent one of said openings; and a heat exchange member electrically and heat conductively connected to said junction and having two grooves snugly receiving the electrically insulating Walls of said openings, respectively.

8. Thermo-electric device operating with the Peltier effect comprising: a tubular element for a heat exchange medium passing therethrough and including electrically insulating means defining two openings aligned transversely to the axis of the tubular element; a thermocouple having a junction being disposed outside of said tubular element adjacent one of said openings; a heat exchange member passing through said opening and being electrically and heat conductively connected on one end with said junction; and a screw for tightening the other end of said member to the adjacent portion of said tubular element.

9. Device as set forth in claim 8, including at least one Washer for sealing at least one of said openings With respect to the portion of said member passing through.

10. Therrno-electric device operating with the Peltier eifect comprising: a tubular element for a heat exchange medium passing therethrough; a plurality of thermocouples disposed outside of and along said tubular element, each thermo-couple having a therrno-couple junction; and heat exchange members electrically and heat conductively connected to said junctions of the same type of the several thermo-couples said tubular element including protruding into the interior of said tubular element; and insulating means for electrically insulating said members from each other.

11. Device as set forth in claim said plurality of thermo-couples being disposed along said tubular element in axis-parallel relationship therewith.

12. Device as set forth in claim 10 said plurality of thermo-couples being disposed along a helical line on said tubular element.

13. Device as set forth in claim 1, said member including means for enlarging its surface in the direction of flow of said medium.

14. Device as set forth in claim 4, said hose being made of tombac.

l5. Therrno-electric device operating With the Peltier effect comprising: a flexible electrically insulating hose being passed through by a heat exchange medium and having tWo openings aligned transversely with respect to the outer axis of the hose; a thermo-couple having a junction disposed outside of said hose including a supporting plate being disposed directly secured in electrical and heat conductive relationship to said plate and passing through said tWo openings secured to said plate and passing through said two openings so as to extend transversely to the flow of said medium; and means for sealing said openings.

References (hired in the file of this patent UNITED STATES PATENTS

Claims

1. THERMO-ELECTRIC DEVICE OPERATING WITH THE PELTIER EFFECT COMPRISING: A TUBULAR ELEMENT FOR A HEAT EXCHANGE MEDIUM PASSING THEREGTHROUGH AND HAVING AT LEAST ONE APERTURE THE WALLS OF WHICH ARE ELECTRICALLY INSULATING; AT LEAST ONE THERMO-COUPLE DISPOSED OUTSIDE OF SAID TUBULAR ELEMENT AND INCLUDING MEANS DEFINING A THERMO-COUPLE JUNCTION BEING DISPOSED ALSO OUTSIDE OF SAID TUBULAR ELEMENT; AND A HEAT EXCHANGE MEMBER ELECTRICALLY AND HEAT CONDUCTIVELY CONNECTED TO SAID MEANS DEFINING SAID JUNCTION AND PROTRUDING THROUGH SAID APERTURE INTO THE INTERIOR OF SAID TUBULAR ELEMENT WHILE EXTENDING SUBSTANTIALLY ACROSS THE AXIS THEREOF.