US3191391A

US3191391A - Thermoelectric cooling apparatus

Info

Publication number: US3191391A
Application number: US164079A
Authority: US
Inventors: Muller Heinz
Original assignee: Siemens Elektrogaerate GmbH
Current assignee: SEG Hausgeraete GmbH
Priority date: 1961-01-06
Filing date: 1962-01-03
Publication date: 1965-06-29
Anticipated expiration: 1982-06-29
Also published as: DE1193072B; GB949123A; FR1310228A

Description

June 29, 1965 H. MULLER 3,191,391

THERMOELECTRIC COOLING APPARATUS Filed Jan. 5, 1962 2 Sheets-Sheet'l Fig. 1

IlIIIIIII/II/ Jnvenfor:

June 29, 1965 H. MULLER v 3,191,391

THERMOELECTRIC COOLING APPARATUS Filed Jan. 3, 1962 2 Sheets-Sheet 2 Fig. 3

Jnvgnfor:

United States Patent 3,191,391 THERMOELECTRIC COOLING APPARATUS Heinz Miiller, Berlin-Charlottenburg, Germany, assignor to Siemeus-Electrogerate Aktiengesellschaft, Berlin, Germany, a corporation of Germany Fiied Jan. 3, 1962, Ser. No. 164,079 Claims priority, appligatliorsglermany, Jan. 6, 1961, 1

8 Claims. (or. 62-3) My invention relates to cooling apparatus, such as refrigerator cabinets, in which the cold-producing devices consist of batteries or blocks of thermocouples traversed, when in operation, by electric current to lower in each couple the temperature of one junction (cold junction) relative to the temperature of the other junction (hot junction).

The efiiciency of such Peltier blocks is effected by detrimental heat losses due to direct heat exchange between the cold-junction side and the hot-junction side of the block. In order to minimize such heat losses it has been proposed to mount the Peltier blocks, each comprising a multiplicity of thermocouples and interconnecting metal conductors or bridge pieces, into a vacuum container. Devices of this type, however, encounter difficulties if the vacuum jacket of the vessel extends close to the Peltier block because then the cold-junction may be subjected to heating from the hot-junction side particularly since the distances between hot side and cold side in most cases are relatively short.

It is an object of my invention, therefore, to provide a Peltier cooling apparatus, employing a vacuum container, in which the detrimental heat flow is greatly reduced.

To this end, and in accordance with a feature of my invention, the heat exchange on the hot side and on the cold side of the Peltier block is elfected by means of respective circulation systems which contain a flowing heattransfer medium, preferably a liquid subjected to evaporation and condensation during its course of circulatory travel. The arrangement is such that the heat exchangers of both systems, which are in direct heat exchange with the Peltier block, are located completely within the vacuum container together with the Peltier block, and only the circulation lines of the heat exchanging systems are in thermal contact with the wall of the vacuum container at those localities where they pass through the wall.

As a result, and in accordance with another feature of my invention, the Peltier block can be built into a large area vacuum vessel, so that the heat flow from the hot to the cold side of the Peltier block can be greatly minimized. In the novel apparatus such a heat flow takes place only from the pipes of the heat exchanger system inserted into the vacuum container on the hot side of the Peltier block, to the corresponding pipes appertaining to the heat exchanger system located in the vacuum space on the cold side of the block, It is particularly favorable that the path between these two localities where the pipes pass through the sheet metal of the vacuum housing is relatively long. It is, therefore, readily feasible and not detri mental, to directly weld the pipes of the circulatory exchange, or lines at the wall intersection points, directly to the metal of the vacuum container. The vacuum container is preferably made of stainless steel, for example chrome-nickel steel. In this case the heat flow can be fur' ther reduced by using extremely thin sheets of steel since the. heat conductance of this material is small.

If it is desired to obtain a particularly effective reduction in heat flow between the pipe-entering localities of the vacuum housing, the pipes of the circulation lines can be inserted into the metallic wall of the vacuum vessel with the aid of an insulating intermediate layer, for example a molten glass plug or sleeve. Another way of greatly reducing the heat flow is to construct the wall of the vacuum container from a non-metallic material, particularly a synthetic plastic particularly suitable for such purposes.

When employing the invention in conjunction with cabinets, containers or other cooling chambers surrounded by heat-insulating walls, the dimensions of the vacuum container can be adapted to the thickness of the insulating wall and a mounting opening left vacant in that insulating wall so that the vacuum container constitutes a closure and cover for the mounting opening and the walls of the vacuum container form on both sides a continuation of the outer and inner surfaces on the insulating wall and preferably substantially flush with the latter surfaces. In this manner a good utilization of the available space is obtained because only the heat receiving and heat dissipating parts proper of the circulatory heatexchanger systems protrude out of the insulating wall into the cooling chamber on the one hand and into the ambient air on the other hand. The nipple for the connection of a pump, and the in-leads for the electric conductors to be connected to the Peltier block, in devices of the latter type, are preferably arranged on the external wall of the vacuum container facing the hot side of the apparatus.

The foregoing and more specific features of the invention will be apparent from, and will be described in, the

following with reference to the drawing showing, by way of example, an embodiment of Peltier cooling apparatus.

according to the invention.

FIG. 1 shows schematically and in section a Peltier apparatus together with part of an insulating wall structure in which the system is mounted;

FIG. 2 shows in perspective the Peltier block of the same apparatus; and

FIG. 3 shows a modified part of the Peltier apparatus of FIG. 1.

Like parts are identified by the same reference numerals in the figures.

Denoted by 1 and 1a are the thermoelectrically different legs of a Peltier thermocouple which are interconnected by electrically and thermally conducting bridge pieces 2 consisting, for example of copper. Each leg is further connected with the leg of an adjacent couple by another bridge piece 2. In this manner a large number of thermocouples are combined into a single Peltier block which will be more fully described hereinafter.

The hot-junction side of the block is in contact with the pressure pot 3 serving as an evaporator. The coldjunction side of the block is analogously in contact with the planar wall of another pressure pot 4 designed as a condenser. Both pressure pots may consist of stainless steel or any other suitable material of sufiicient strength. This is so because both are inserted into a vacuum container and the heat exchange between the Peltier couples and the environment is effected by the evaporating and recondensing liquids contained in the two heat exchanging systems of which the evaporator 3 and the condenser 4 form parts. The pressure pot 3 operating as evaporator is a component of the heat transfer system whose external air-cooled condenser is denoted by 5. The appertaining circulatory linesof this system, consisting of material well suitable for welding or hard-soldering, for example steel or copper, are denoted by 6 and 7. The pressure pot 3 on the cold side of the Peltier block, operating as condenser, forms a component of a second heat transfer system which comprises an evaporator 8 located in the internal evaporator of the refrigerator cabinet or other cooling chamber that is to be cooled by means of the thermoelectric apparatus. Both heat transfer systems operate on the principle of evaporating and condensing a liquid coolant or refrigerant. By means of tensioning bolts 12 the two

pressure pots

3 and 4 are firmly stressed against each other and against the Peltier block to form a good heat conducting contact therewith.

The entire apparatus unit, constituted by the two

pressure pots

3, 4 and the intermediately located Peltier block is completely inserted into a vacuum chamber 13 which is enclosed by the

walls

14, 15 and 16 of a vacuum container. A direct heat contact between the Peltier block and the walls of the vacuum container in this embodiment exists only at the welding locations 17 where the circulating

pipes

6 and 7 are welded into the upper wall 14, and at the corresponding welds 18 where the circulating

pipes

10, 11 enter through the lower wall 16 of the vacuum container. Denoted by 19 is the external sheet-metal structure, and by 20 the internal sheet-metal wall of a refrigerator cabinet. The space between these two sheet-metal skins is filled with heat insulation 21 consisting for example of glass wool. As mentioned, the cooler refrigerating chamber within the cabinet is located beneath the wall 20 to be cooled by the evaporator 8. The dimensions of the vacuum container are adapted to the thickness of the cabinet wall structure and to the size of a mounting recess 22 so that the vacuum container forms a closure for the mounting recess 22 and its

outer walls

14 and 16 are substantially flush with the outer and

inner sheets

19 and 20 of the cabinet wall structure. The pump nipple 23 and an in-lead 24 for the electric cable is located in the outer vacuum-container wall 14 facing the hot-junction side of the Peltier block.

In the modification of FIG. 3, the circulating

pipes

6, 7 and 10, 11 instead of being welded to the

vacuum containing walls

14 and 16, respectively, are inserted through insulating plugs or sleeves 25 of glass, for example, that are mounted in openings in the walls.

' While the Peltier block is shown only schematically in FIGS. 1 and 3, details of its design are apparent from FIG. 2. The respectively

different legs

1 and 1a of each couple consist of semiconductor bodies of p-type and H- type material. Suitable, for example, as p-type material is a solid solution of bismuth telluride and antimony telluride. Suitable as n-type material is a solid solution of bismuth telluride and bismuth selenide. The top and bottom sides of each

leg

1 and 1a are made solderable by electroplating with copper or nickel or by vapor deposition of such metals, with or without simultaneous application of ultrasonics. The n-type and p-type semiconductor bodies are all serially connected by the currentconducting bridge pieces 2 so that all hot junctions face upwardly in the illustrated embodiment of FIG. 1, and all cold junctions face downwardly. Connected to the first and last semiconductor body of the entire block are

terminal pieces

25 and 26 to which respective electric leads are attached in order to pass current through the entire block.

It will be understood, however, that the particular choice of the materials for the legs of the Peltier couples as well as the manufacture of the Peltier block as such, are not essential to the inventionproper and may be modified in various respects. For example, such other materials and manufacturing methods may be used as are described in US. Patent No. 2,978,570 and in the copending application Serial No. 150,701, of W. Hanlein for Thermoelectric Battery and Method of Its Production, filed November 7, 1961.

It will also be obvious to those skilled in the art, upon studying this disclosure, that various modifications are applicable with respect to design and arrangement of the components, and hence that the invention can be given embodiments other than particularly illustrated and described herein, without departing from the essential features of my invention and within the scope of the claims annexed hereto.

I claim:

1. Apparatus for thermoelectric cooling comprising a multiplicity of electrically interconnected thermocouples jointly forming a block having a cold-junction side and a hot-junction side, two heat transferring circulation systems each having a fluid-containing vessel joined in direct heat contact with said block at one of said respective sides for heat exchange with said block, a relatively thinwalled vacuum container in which said block and said two vessels are mounted in spaced relation to the container walls, each of said two circulation systems having fluid lines extending from one of said respective vessels through the container wall to the outside thereof, whereby any heat contact with said container is limited to the passages of said lines through said walls.

2. Apparatus for thermoelectric cooling comprising a multiplicity of electrically interconnected thermocouples jointly forming a block having a cold-junction side and a hot-junction side, two fluid circulation systems containing an evaporable and condensable coolant and each having an evaporator and a condenser and interconnecting fluid lines, the evaporator of one of said systems and the condenser of the other system being joined with said block in direct heat-conductive contact therewith on said two respective sides thereof for heat exchange with said block, a relatively thin-walled vacuum container, said block joined with said latter evaporator and said latter condenser being mounted in said vacuum container in spaced relation to the container walls, said other evaporator and said other condenser being disposed outside of said container, and said lines extending from within to without said container through said walls, whereby any heat contact with said container is limited to the passages of said lines through said walls.

v 3. Apparatus for thermoelectric cooling comprising a multiplicity of electrically interconnected thermocouples jointly forming a block having a cold-junction side and a hot-junction side, two heat transferring circulation systems each having a fluid-containing vessel joined in direct heat contact with said block at one of said respective sides for heat exchange with said block, a vacuum container having relatively thin metal walls, said block and said two vessels being disposed in said vacuum container in spaced relation to said walls, each of said two circulation systems having fluid lines extending from one of said respective vessels through the container wall to the outside thereof, and said lines being fusion-joined with said walls at the locality where the lines pass through the walls.

4. In thermoelectric cooling apparatus according to claim 1, said vacuum container comprising insulating inserts mounted in said walls and traversed by said lines.

5. In thermoelectric cooling apparatus according to claim 1, said vacuum container consisting of stainless chrome-nickel steel.

6. Apparatus for thermoelectric cooling comprising a cooling-chamber structure having a heat-insulated wall and having an opening in and through said wall, a relatively thin-walled vacuum container substantially matching said opening and being inserted therein, said container forming a closure for said opening, a Peltier block comprising a multiplicity of electrically interconnected thermocouples and having a cold-junction side and a hot-junction side, two heat transferring circulation systems each having a fluid-containing vessel joined in direct-heat contact with said block at one of said respective sides for heat exchange with said block, said block and said two vessels being disposed in said vacuum container in spaced relation from the container walls, and each of said two systems having fluid lines extending from one of said respective vessels through the container wall to the outside thereof.

7. In thermoelectric cooling apparatus according to claim 6, said cold and hot sides of said block being paral- 5 6 lel to the surfaces of said heat-insulated wall, and'said References Cited by the Examiner vacuum container having its outer and inner surfaces UNITED STATES PATENTS substantially flush with the outer and inner surfaces respectively of said heat-insulated wall. 2,109,002 2/38 Warren 62.26? 8. In thermoelectric cooling apparatus according to 5 2,947,150 8/60 Roefler claim 6, said vacuum container having a pump-connection 3,054,840 9/62 Alsmg 62 '3 nipple and an electric-cable in-lead both located in the container wall that faces said hot-junction side of said WILLIAM Primary Exammer block. ROBERT A. OLEARY, Examiner.

Claims

1. APPARATUS FOR THEREMOELECTRIC COOLING COMPRISING A MULTIPLICITY OF ELECTRICALLY INTERCONNECED THEREMOCOUPLES JOINTLY FORMING A BLOCK HAVING A COLD-JUNCTION SIDE AND A HOT-JUNCTION SIDE, TWO HEAT TRANSFERRING CIRCULATION SYSTEMS EACH HAVING A FLUID-CONTAINING VESSEL JOINED IN DIRECT HEAT CONTACT WITH SAID BLOCK AT ONE OF SAID RESPECTIVE SIDES FOR HEAT EXCHANGE WITH SAID BLOCK, A RELATIVELY THINWALLED VACUUM CONTAINER IN WHICH SAID BLOCK AND SAID TWO VESSELS ARE MOUNTED IN SPACED RELATION TO THE CON-