FR2620573A1 - Heat/electricity transducer panel with plural thermocouples in the form of a thin concertinaed film - Google Patents

Abstract

Thermoelectric panel with plural thermocouples whose conductors made alternately of two materials 10 and 11, are arranged as a thin film in long parallel strips perpendicular to the length of the film. The concertinaed film forms a parallelepipedal panel. The heat crosses it through the large faces which carry the junctions 12 and 13. According to a preferred embodiment, the conductors are deposited on an insulating support film 17. Rods passing through the folds provide for the holding of the panel. Bars bearing against the end regions compress the folds and transmit the electrical current to the connections. General uses: manufacturing current from a temperature difference (Seebeck effect), or heat or cold from an electric current (Peltier effect). Particular uses: solar energy pick-up for artificial satellite, heating and cooling of an insulated enclosure by programmed cycle, cylindrical duct for channelling a fluid.

Description

 The present invention relates to a thermoelectric transducer panel structure for the exchange of heat energy into electricity (and vice versa), manufacturing processes and uses thereof.

 The Seebeck effect has been known for more than a century: an electric current appears in a circuit consisting of two conductors (10) and (11) of different compositions and adequate to exhibit a thermoelectric effect when their junctions <12 ) and (13) are set at different temperatures (see Plate 1/3 Figure 1). Conversely, a difference in temperature occurs when a current flows through the circuit (Peltier effect).

 The tensions put into play depend on the two materials put in contact, but they are always very weak. For example, the copper / constantan pair has a characteristic voltage of 40.10 volts per degree of temperature difference between the two junctions. To get closer to commonly used voltages, it is necessary to connect in series a very large number of junctions, several thousand or even tens of thousands (see Figure 2). The conductor is then formed of a succession of elementary conductors alternately of a material and then of the other, such that their junctions are alternately on the side of the hot source and the side of the cold source.

 The methods usually used to perform this Bise in series or achieve heat exchangeelectricity on very small surfaces and can not then transmit significant power, or use complex manufacturing techniques and storytelling because difficult to automate.

 In order to overcome these drawbacks, the present invention makes it possible to produce a transducer panel of large area such that heat and cold are exchanged through the two large opposite faces of this panel, and this according to a sinful disposition permitting to execute the lilliers. junctions of a den little storyteller because fully automatic.

 For this purpose, the panel of the present invention uses a conductor composed me body above a very large number of unitary conductors whose dots are alternating, but whose section is that of a film, that is to say that is, the thickness of the conductor is extremely low and its width very large relative to this thickness. The unit conductors are formed of long parallel strips arranged perpendicularly to the length of the film, each strip having a length equal to the width of the fila since it extends from one side to the other of the film, the material of each strip being alternatively one then the other as previously indicated.

 The film thus formed is folded accordion so that the folds correspond alternately to hot and cold junctions. The general fora of the panel is a rectangular parallelepiped whose large face carries the "hot" junctions and the large opposite face the "cold" junctions.

 The heat is exchanged through these large faces. The current flows following the conductive film zigzag in a general direction parallel these large faces.

 To better understand this structure, reference is made to FIG. 3 which shows in perspective the fora of the conductors of the panel.

 The conductors (10) and (11) have a general section shaped wire nince, that is to say that their thickness is extremely low and their width is very large relative to this thickness. These conductors are drilled long parallel strips of length equal to the width of the rope, these strips being arranged perpendicular to the length of the film from one side to the other of the film. The zateriau of the conductors is alternately one (10) then the other (11) of the two Materials.

 The film thus formed is folded accordion so that the folds alternately correspond to the "hot" junctions (12) and the "cold" junctions (13). The folded assembly has the general appearance of a parallelepipedic panel (14) whose "hot" junctions are located on a large face and the "cold" junctions on the large opposite face.

 The heat is exchanged through these large faces in the direction of the arrow (15), the current flows along the zigzag conductors in a general direction (16) parallel to the large faces.

 For the clarity of the drawing, the thickness of the film has been greatly increased and the other dimensions (widths, length and number of plies) greatly reduced. In fact, the film is thin enough and the pitch of the folds is reduced enough that the stacking of thousands of folds gives the panel a reasonable length relative to its width.

 At a temperature gradient between the two large faces of the panel corresponds an electrical potential difference between the ends of the conductor formed by the thermoelectric materials (and vice versa). A heat flow corresponds to an electric current (and vice versa).

 The panel can be used as a current generator from a temperature difference (Seebeck effect), or reverse as a generator of heat or cold from an electric current (Peltier effect).

 The thermoelectric qualities of the materials vary according to the temperature and it would be interesting to make each junction work at the temperature for which its characteristics are the best. Unfortunately, this can not be attained both by the temperature of the hot spring and the temperature of the cold source.

 When the difference in temperature between the two faces of the panel justifies it, it is possible to insert between the "hot" (12) and "cold" junctions (13) one or more interpositional junctions such that each junction works in a zone of the temperature for which its characteristics are the best. This is obtained as illustrated in the sectional view 4 by splitting the strips (10) and (11) into several partial bands (10 '), (10' '), (10' ''), ... and (11). ), (11 '), (11' ''), ..., the composition of each strip being adapted to the temperature corresponding to its position in the panel.

 According to a preferred embodiment of the panel which is the subject of the invention, a continuous thin insulating support film is used on which the unit conductors are deposited under foras of alternating parallel strips of the names of two materials as indicated above. covering slightly over one another for electrical continuity.

 An insulating film covers the conductors to provide insulation between folds when the film thus composed will be folded accordion.

 The whole will then form a conpact parallelepipedal panel.

 The board 2/3 presents in perspective the structure of the transducer panel made according to this embodiment.

 For the clarity of the illustrations, the thickness of the films here has also been greatly exaggerated with regard to its length and width, and the number of folds greatly reduced.

 In Figure 5, the film is shown flat. The insulating film (1) supports the individual conductors (10) and (11), which are deposited in long alternating parallel strips with a slight overlap to ensure electrical continuity.The section of the conductor is a thin wire.

 In Figure 6, the assembly was covered with an insulating film (18) prohibiting any electrical contact between adjacent conductive surfaces, and was folded accordion. The folds correspond alternately to the "hot" junctions (12) and the "cold" junctions (13).

 Figure 7 shows that the outer fora of the transducer is a rectangular parallelepipedal panel (14).

 The "hot" (12) and "cold" faces (13) carry the junctions. It is applied (or appears) the temperature difference and the heat flow flows between the large faces of the panel in the direction of the fl ow (15). The potential difference appears (or is applied) on the zones (19) and (20) and the current flows along the arrow (16).

 The ends (19) and (20) corresponding to the first and last deposited strip serve for the electrical connections of the apparatus and are not covered by the insulator (18).

 Rods (21) passing through the folds by perforations in nie tenps the mechanical strength of the panel and the bars (22) and <22 '). These bars rest on the end zones (19) and (20)> They hold the compressed folds and transmit the electric current to the connections <23) and <23 ').

 If, as indicated above, the proportions have been distorted for the clarity of the drawings, the method allows the production of very large panels: the current technique provides, for example, polyester filas 12 microns thick, 2 , 2 meters wide and can reach a length of 20 000 m.

 The panel can thus have a width of 2.2 D and its length will be the thickness of the film (a few hundredths of a millimeter) multiplied by the number of folds (several thousand if necessary).

 with the use of materials of low thernoelectric power, the series setting of these very numerous elements generates acceptable voltages without any problem.

 The dimensions of the panels are easily de-chained to achieve the exchange of any power under any voltages.

 The deposition / folding process is simple and economical to repeat autosaturally at infinity.

 The invention is independent of the materials used: the support wire (17) and the insulating film (18) can be any electrical and thermal insulating material in the form of rinsed wire and the materials (10) and (11) any couple of conductors having a thernoelectric effect: nétaux, seDi-drivers, etc ...

 The film (18) can consist of a separate film, or deposited by spraying, or made by chemical action from the materials (10) and / or (il) (for example oxidation-reduction) or obtained by any other method .

 The alternating strips <10) and (11) can be deposited by means of paints or coatings inks of fine particles of materials having the thersoelectric effect, for example P and N-doped semiconductors, the particles being embedded in a binder to facilitate application.

 In a variant, these strips can also be produced by pressure, chemical deposition, electrolytic deportation, spraying, spraying, cathodic sputtering, vacuum metallization, plasma metallization, etc.

 The panel made according to the invention can, among other things, be used as a high-efficiency solar energy sensor aboard an artificial satellite: the "hot" face is exposed to the solar radiation which carries it at high temperatures, and the "cold" face radiates directly on the interstellar space which keeps it at a low temperature.

 Another particular use of the panel according to the invention is to make a tubular conduit in which a fluid circulates (if at least one of the hot or cold sources is a fluid).

 For this, the panel may for example be bent to form a circular cylindrical conduit. The duct could equally well have been formed by several panels, for example 4 panels arranged in a square, which would then drill a square section duct.

 Figure 8 of the board 3/3 gives an example of this type of panel <14 ') curved as indicated above. It surrounds a tube <13 ') fins to facillit the heat exchange and is in turn covered with a plate (12') fins also cylindrical.

 If the tube (13 ') is for example traversed by a hot gas (heated by a braleurf or engine exhaust gas, etc ...), and the outside cooled by air, this assembly constitutes a simple, economical and efficient electric generator.

 According to another use, a panel heats or cools by reversing the current inside a same enclosure either to maintain it at a constant temperature, or on the contrary for the sun to cycles of heat then cold, cycles can be piloted by a programmer.

 FIG. 9 illustrates such a device: a panel (14) heats or cools (by inversion of current) inside an isolated enclosure, the heat cycles being pilot by a programmer <24>. An appliance of this type can, for example, store food by keeping it low and then heat it up to make it fit for food.

 It goes without saying, and as it follows moreover from the foregoing, the invention does not in any way abolish those of its modes of application and of realization which have been more particularly contemplated; on the contrary, it includes all the variants.

Claims (7)

REVEKDICATIONS  1) thermoelectric transducer panel with numerous thermocouples electrically connected in series and thermally in parallel, each formed of at least two materials (10) and (11) alternating and having a thermoelectric effect between them, in order to obtain by the Seebeck effect a high electrical power under high voltage from a "hot" source and a "cold" source, or conversely by Peltier effect of obtaining heat or cold from an electric current, characterized by the use of conductors whose general section is that of a thin rope (that is to say that the thickness of the conductor is extremely small and its width very large compared to this thickness), these conductors being formed of long strips parallel films of equal length to the width of the film arranged perpen dicularly to the length of the film (from one bank to another), the film thus constitutes being folded accordion so that the folds correspond alternativenent to the "hot" junctions (12) and the "cold" junctions (13), the general fora obtained being a rectangular parallelepipedic panel (14), a large face of which bears the "hot" junctions (12) and the opposite large face the "cold" junctions (13), the heat exchange (15) being made through these two large faces and the current flowing in a general direction (16) parallel to these faces.  2) thermoelectric transducer panel according to claim 1, characterized in that the conductors are deposited on a thin insulating film and continuous continuous (17), the film thus formed being, before folding accordion, coated with another insulating film (18). ) except on the first and the last strip which provides the electrical connections (19) and (20).  3) thermoelectric transducer panel according to claims 1 or 2 characterized by rods (21) and bars (22) and (22 '), the rods passing through the folds by perforations to ensure the mechanical strength of the panel and support the bars ( 22) and (22 '), these bars in turn resting on the end zones (19) and (20) in order to maintain the folds confined and transmit the electric current to the connections (23) and (23') .  4) Thermoelectric transducer panel according to any one of the preceding claims characterized by its use as a solar energy sensor aboard an artificial satellite, the "hot" face being exposed to solar radiation and the "cold" face radiating in the interstellar space .  5) Thermoelectric transducer panel according to any one of the preceding claims for carrying out heat / electricity exchange in the noyen of at least one fluid, characterized in that the panel (14 ') (or a set of panels has been arranged in foras of cylindrical tubular duct such that the fluid can circulate inside this duct.  6) thernoelectric transducer panel according to any one of the preceding claims for heating or cooling the interior of a pregnant e, either to maintain a constant temperature, or on the contrary to submit it to cycles of heat and then cold, characterized in that the reheating and cooling are performed by current reversal.  7) Thermoelectric transducer panel according to the preceding claim characterized in that the heat and cold cycles are controlled by a programmer.