RU2310950C1 - Thermoelectric element - Google Patents

Abstract

FIELD: heat-to-electric energy conversion; controlling and measuring temperature of various pieces of equipment.

SUBSTANCE: proposed thermoelectric element has electrodes made in the form of two or more film layers of materials characterized in different Peltier effects. Surface wherefrom heat is transferred to piece of equipment under temperature control is outer surface of film electrodes. Switching contact pads of layers are disposed beyond region under heat control for heat exchange with surrounding medium. Current flow from one film to another will cause absorption (and release) of heat throughout entire contact area of layers. Thermoelectric element can be built of two or more series- or parallel-connected thermal elements. Film electrodes can be made of transparent materials.

EFFECT: facilitated manufacture, reduced width and thermal lag at effective heat transfer.

3 cl, 3 dwg

Description

The invention relates to the field of technical physics and is intended, in particular, for use in electronics and in optical systems for detecting and displaying information.

Known thermoelectric devices based on the Peltier effect (US patent No. 3006979, 4859250, 3409475 and others). They are made of a pair or multiple pairs of electrodes in the form of columns of materials with different Peltier coefficients, which are mounted and connected so that the connections through which the current flows from the electrodes of the first material to the electrodes from the second are in the same plane, and the connections through which the current flowing from the second to the first, were in a different plane parallel to the first. These compounds are in thermal contact with the surface of the plates, the second surface of which is a heat transfer surface. When current flows through these devices in the region of one of the planes, heat is absorbed, and in the region of the other, it is released. Such battery cells can be multi-stage (US patent No. 5040381, 4833889, 5385022).

The disadvantage of these devices is cumbersome, limiting or excluding the possibility of their use, uneven heat transfer on the surface and the complexity of manufacturing.

Also known is a thermal device, consisting of series-connected and in the same plane alternating strips of flat electrodes from materials with different Peltier coefficients. Joints of couples that cool during the passage of current are grouped in the temperature-controlled region, and joints of the opposite type are grouped in the region of heat removal. The electrodes are made of copper foil and constantan foil (US patent No. 3607445).

Its disadvantage is the unevenness of the heat sink due to the small surface area of the heat transfer, which is limited by the area of the junction of the electrodes, as well as the low manufacturability. In addition, the large area of opaque electrodes limits the use of the device in optical devices.

The prototype of the invention is a thermocouple in the form of a thin-film thermocouple deposited directly on a temperature-controlled microchip element (JP 11-015539), which removes heat from this element due to the Peltier effect. The dimensions of the thermoregulated region are comparable with the thickness of the thermocouple.

The disadvantage of the prototype is the location of the switching platforms (contacts to the film layers of the thermocouple) in the temperature-controlled region, which leads to the heating of these contacts (due to the same Peltier effect) and, therefore, to the return of the removed heat to the temperature-controlled region by the mechanism thermal conductivity. With small sizes of objects for which a thermocouple is proposed, the efficiency of the thermal conductivity mechanism is especially large and reduces the work of this thermocouple to nothing. The opacity of the electrodes limits the use of the device in optical instruments.

The technical problem solved by the invention is to increase the efficiency of heat removal, creating the possibility of heat dissipation from individual local zones of a thermally controlled object without additional heating of neighboring areas, as well as expanding the possibilities of using a thermocouple.

The problem is solved in that the thermocouple is made, in one of the options, in the form of a two-layer film, the layers of which are electrodes and are made of materials with different Peltier coefficients. With the passage of current from one film to another, heat will be absorbed (or released) over the entire contact area of the layers. In this case, both layers will be simultaneously cooled (or heated), therefore, both surfaces of a two-layer film can be used as heat exchange surfaces with a temperature-controlled object. The geometry of the film layers is such that the switching pads of the layers (i.e., electrical contacts to the layers) are located outside the temperature-controlled region in order to exclude heat exchange between them and the temperature-stabilized region by the heat conduction mechanism. The heat absorbed (or released) in the field of thermoregulation is released (or absorbed) at the switching sites, and the heat exchange between these sites and the environment is organized by any known method. The distance by which the proposed device removes heat from the temperature-controlled region is equal to the distance from it to the switching platforms and can be made arbitrarily large (the restriction is imposed only by secondary reasons).

The location of the switching pads outside the temperature-controlled region leads to the fact that the heat released or absorbed at these contacts during the flow of current is transferred not to the temperature-controlled object, but to the environment. In this case, the heat from the heated zone is transferred not through the areas adjacent to this zone with their associated heating, but to the zone located outside the thermoregulated area, for example, directly to the external heat transfer radiator (the same for supplying heat).

To increase thermal efficiency, one or both film electrodes are made of a semiconductor material. In this case, to optimize the properties of the thermocouple (for example, to increase the reverse current of the resulting pn junction), the adjacent surfaces of the semiconductor films can be modified or separated by a film of a third material (for example, to create an ohmic contact).

The area of thermal stabilization of the proposed device is evenly distributed over the entire contact area of the layers. In this case, the contact region of the layers is separated from the temperature-controlled surface by only a thin layer of the film electrode, which creates good conditions for heat transfer.

A thermocouple, consisting of many of the elements described above, switched in series, parallel or otherwise, expands the possibilities of application.

The proposed design of the thermocouple allows you to create a large concentration of single thermocouples on a thermoregulated surface, which is essential for the use of thermocouples as part of various sensors and converters (for example, alternating current to direct current or radiation intensity to direct current), as well as to reduce the power supply current of Peltier batteries while maintaining the discharge (input) thermal power.

A battery composed of several layers (cascades) of such thermocouples further increases the thermal effect. Electrical connections between individual thermocouples and layers can be different (serial, parallel, etc.) and are carried out at the switching sites.

In the multi-stage version, the proposed device does not work in the same way as in multi-stage analogs, where the heat is transferred from the cascade to the cascade and the power taken is equal to the power of the weakest link: here all the cascades remove heat from the temperature-controlled object to the switching platforms without transferring it to each other, and the heat is removed power sums up. In addition, the proposed device has a low thermal inertia due to the low mass of the electrodes.

To expand the possibilities of use, for example, in optical devices, film electrodes in the proposed device can be made of transparent materials.

In all embodiments, the proposed device can be used as a cooler, heater, temperature sensor or converter.

The drawings depict variations of the invention.

The numbers denote: 1 - a device with a temperature-controlled element; 2 - work area (temperature control area); 3 - p-type film; 4 - n-type film; 5 - area of switching platforms; the signs “+” and “-” indicate the polarity of the voltage during cooling and heating (in brackets) of the object.

Figure 1 - a single thermocouple with electrodes of semiconductor materials in the context.

Figure 2 - a single thermocouple with electrodes of semiconductor materials in plan.

Figure 3 - option with a serial connection of thermocouples.

An example of a specific embodiment of the invention as a cooler is a single thermoelement, the electrodes of which are made in the form of n- and p-type zinc oxide films with a specific resistance of 0.0001 ohm · cm on a glass surface with a temperature-controlled (working) square area of 10 cm 10 cm with extensions of each of the films (in one layer) 1 cm wide and 5 cm long to the switching platforms located on the radiator. The thickness of the films deposited by chemical transport is 0.01 mm. This thermocouple allows you to remove 10 watts of heat from the working area.

Claims (3)

1. A thermoelectric element comprising electrodes made of materials with different Peltier coefficients and having a heat exchange surface, characterized in that the electrodes are made in the form of two or more film layers of materials with different Peltier coefficients, the heat exchange surface with a thermally controlled object is their outer surface, and switching the layer pads are located outside the temperature-controlled region for the implementation of heat exchange with the environment. 2. The thermocouple according to claim 1, characterized in that it consists of two or more electrically connected in series and / or parallel connected thermocouples. 3. The thermocouple according to claim 1 or 2, characterized in that the film electrodes are made of transparent materials.

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