ES2610507B1 - THERMOELECTRIC GENERATOR AND HEATING EQUIPMENT THAT INCLUDES SUCH THERMOELECTRIC GENERATOR - Google Patents

Abstract

Thermoelectric generator and heating apparatus comprising said thermoelectric generator. # The present invention relates to a thermoelectric generator that allows reducing the temperature reached by a thermoelectric module of the electric generator itself given that the heat transfer by conduction between a heating apparatus where It is arranged and the thermoelectric module itself is canceled and the layer of air that is created between the two elements acts as an insulator. The invention also relates to the heating apparatus comprising the thermoelectric generator.

Description

THERMOELECTRIC GENERATOR AND HEATING EQUIPMENT THAT INCLUDES SUCH THERMOELECTRIC GENERATOR

DESCRIPTION

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OBJECT OF THE INVENTION

The present invention relates to a thermoelectric generator that allows to reduce the temperature reached by a thermoelectric module of the electric generator itself since the heat transfer by conduction between a heating apparatus where it is arranged and the thermoelectric module itself is canceled or minimized and the layer of air that is created between the two elements acts as an insulator.

The invention also relates to the heating apparatus comprising the thermoelectric generator.

BACKGROUND OF THE INVENTION

20 Wood, pellet and coal stoves or homes that are widely used as heating equipment, especially in remote locations, are known in the prior art.

Encouraged by the new regulations that impose greater efficiencies in 25 heating equipment, the manufacturers of stoves or homes have been incorporating improvements that go along this line. These devices currently include a heat exchanger that receives heat from combustion to heat the ambient air. A circulation fan forces the ambient air through the heat exchanger. A significant disadvantage of the majority of these equipments is that they require mains power to operate the circulation fan. Therefore, they are inoperable during the

power outages, when they are most necessary. Second, the energy

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They consume is increasingly expensive.

Known thermoelectric devices are also used in reverse mode to convert heat from the stove into electrical energy that can be used to power external loads. Heat passes through a hot side plate of the generator to a cold side plate, where a thermoelectric module uses the temperature difference between the hot side plate and the cold side plate to convert heat into electrical energy. Therefore, the greater the temperature difference between the hot side plate and the cold side plate 10, the more electrical power is generated.

Among these systems, the patent application US20080245352 is known relative to a thermoelectric generator for use with a stove, which has a thermoelectric module attached to one of the walls of the hearth that forms the enclosure of the combustion zone. The energy generated is used to drive fans that keep the back side of the module cold and at the same time allow more power to be generated to power other accessories.

Of this same type, the US6588419 patent relating to a stove for the generation of electricity and the operation of a fan and the CA2470739 patent relating to a system for generating electricity in a home using a thermoelectric module are also known.

25 The thermoelectric modules have a maximum operating temperature, so that when this temperature is exceeded, the welds of the joints between material n and p melt and the thermoelectric module ceases to function. This maximum operating temperature is usually around 200 ° C. Although there are thermoelectric modules that withstand higher temperatures, however, efficiency is related to the maximum working temperature. This means that a module that

withstand 200 ° C will generate more energy at 200 ° C than another that can withstand

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350 ° C having the 200 ° C working temperature, that is, the higher the working temperature it supports, the more expensive the modules are.

In this sense, a technology that can guarantee that the working temperature of the thermoelectric modules will never be exceeded will make the equipment more efficient and economical.

That said, one of the most important points is how the thermoelectric module is protected against excessive temperature, since in a wooden home 10 it is not possible to control it.

US20080245352 includes a bimetallic sheet that acts as a radiation reducer, that is, fire radiation dilates the sheet that stops making contact with the wall where the thermoelectric modules adhere. This embodiment has the disadvantage that the limit temperature cannot be controlled exactly so that it is likely that at some point the maximum allowed will be exceeded causing the system to fail.

In US6588419 and CA2470739 there is no system of overheating protection.

On the other hand, the most suitable area for heat capture is the area closest to the fire, preferably below it. The aforementioned inventions prevent its placement at this point due to the risk of generator 25 failure due to excess temperature if the hottest part of the combustion is directly below the generator.

The thermoelectric module of the present invention solves the above drawbacks by protecting the thermoelectric module from excessive temperatures that can destroy it.

DESCRIPTION OF THE INVENTION

The present invention relates to a thermoelectric generator that feeds one or several auxiliary devices of a heating apparatus, where the electric generator allows to reduce the temperature reached by a thermoelectric module 5 of the electric generator itself since the heat transfer by conduction between a heating apparatus where it is arranged and the thermoelectric module itself is canceled or minimized and the layer of air that is created between the two elements acts as an insulator.

The thermoelectric generator comprises at least one thermoelectric module arranged in direct or indirect contact with a collection wall of a heating apparatus, where the at least one thermoelectric module is movable with respect to the collection wall of the heating apparatus by means of a displacement device that carries out the separation of at least one thermoelectric module from the collection wall of the heating apparatus when a hot face of the at least one thermoelectric module is above a first predetermined temperature.

Optionally, the thermoelectric generator comprises an inertial block that is in contact with the at least one thermoelectric module and that acts as a thermal reservoir that accumulates thermal energy when the separation of the at least one thermoelectric module from the collection wall is carried out of the heating device. Preferably, the at least one thermoelectric module is arranged in indirect contact with the pick-up wall of the heating apparatus through the inertial block

In this way, the inertial block maintains the temperature for a while while the at least one thermoelectric module is separated from the collection wall of the heating apparatus.

Once the at least one thermoelectric module, or failing that the block

inertial has cooled down, this or that folds back making contact again

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With the catchment wall. The heating and separation cycle is restarted as long as the first predetermined temperature is exceeded. With this, it is possible to keep the electricity generation relatively constant and prevents the auxiliary devices of the heating apparatus from ceasing to function.

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It is important to note that the electric generator can be coupled to any heating device, be it a stove / home, or for example a blast furnace where the walls of the fume hoods can reach temperatures above 500 ° C.

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Optionally, the electric generator further comprises at least one heat sink that maintains the temperature of a cold face of the at least one thermoelectric module below a second predetermined temperature.

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The invention also relates to a heating apparatus comprising at least one thermoelectric generator as described above.

The heating apparatus further comprises at least one auxiliary device 20 that is powered by the thermoelectric generator, the auxiliary device preferably being a fan.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a perspective view of the thermoelectric generator of the present invention according to a first preferred embodiment.

Figure 2 shows a bottom view of Figure 1.

30 Figure 3 shows an elevation view of Figure 1.

Figure 4 shows a sectional view AA of Figure 2.

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Figure 5 shows a front perspective view of the heating apparatus of the present invention comprising the thermoelectric generator of the first preferred embodiment.

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Figure 6 shows a rear perspective view of the heating apparatus of the present invention comprising the thermoelectric generator of the first preferred embodiment.

10 Figure 7 shows a perspective view of the thermoelectric generator of the present invention according to a second preferred embodiment.

Figure 8 shows a bottom view of Figure 7.

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Figure 9 shows an elevation view of Figure 7.

Figure 10 shows a view of Figure 9 when the hot face of the at least one thermoelectric module is above the first predetermined temperature.

PREFERRED EMBODIMENT OF THE INVENTION

Next, the thermoelectric generator 25 of the present invention will be described in detail.

The thermoelectric generator comprises at least one thermoelectric module (4, 54) arranged in indirect contact with a collection wall (17) of a heating apparatus (1), where the at least one thermoelectric module (4, 54) 30 is movable with respect to the collection wall (17, 67) of the heating apparatus (1) by means of a displacement device (9, 59) that carries

the separation of the at least one thermoelectric module (4, 54) from the wall

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of collecting (17, 67) of the heating apparatus (1) when a hot face (2, 52) of the at least one thermoelectric module (4, 54) is above a first predetermined temperature, which is preferably 200 ° C .

The thermoelectric generator comprises an inertial block (8, 58) that is in contact with the at least one thermoelectric module (4, 54) and that acts as a thermal reservoir that accumulates thermal energy when the separation of the at least one is carried out. a thermoelectric module (4, 54) of the collection wall (17, 67) of the heating apparatus (1), where the at least one thermoelectric module (54) is arranged in indirect contact with the collection wall (17 , 67) of the heating apparatus (1) through the inertial block (58)

The displacement device (9, 59) may have several

15 configurations, preferably being a thermo-mechanical linear actuator or an electric linear actuator. If the displacement device (9) is a thermo-mechanical actuator, it does not need an energy supply to operate, but it is less accurate and can only be calibrated to act at the first predetermined temperature. In case the displacement device (9, 59) is an electric linear actuator, it is configured to reprogram according to the temperature and is very precise. In the event that the thermoelectric modules (4, 54) were replaced and their working temperature varied, only a control electronics that drives the electric linear actuator would have to be reprogrammed.

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The inertial block (8, 58) and everything that is attached to it when the first predetermined temperature is reached is separated by the displacement device (9, 59). With this it is checked that the temperature never exceeds the maximum value bearable by the thermoelectric modules (4, 54) and at the same time 30 that the electric generator always works at its most optimal and efficient point, which is precisely at the first predetermined temperature .

If the displacement device (9, 59) is the electric linear actuator, it has the additional advantage that the separation of the inertial block from the collection wall (17, 67) of the heating apparatus can be adjusted very precisely (one). Another advantage is that it does not consume energy when it is stopped, it only consumes when it moves, that is, when it folds-folds. In this case the generator further comprises a temperature sensor (not shown) arranged in the inertial block (8, 58) so that the control electronics can give the actuation setpoint to the electric linear actuator.

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If the displacement device (9) is a passive actuation system, such as the thermo-mechanical linear actuator, this sensor is not necessary since the same actuator moves, that is to say folds-folds, depending on the temperature.

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The inertial block (8, 58) acts as a thermal reservoir. When the at least one thermoelectric module (4, 54) is retracted, the inertial block (8) accumulates thermal energy. The measurements of this block and the characteristics of thermal conductivity and density allow you to define how much time you can

20 store energy in the form of heat. The larger the inertial block (8, 58), the longer it will store energy. On the contrary, the larger the inertial block (8, 58), the longer it takes for the block to heat up, which leads to the activation of auxiliary devices (5), e.g. fans, later.

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This aspect is important because when the inertial block (8, 58) is separated by action of the displacement device (9, 59), if the inertial block (8, 58) did not have stored energy, the temperature would fall rapidly causing the auxiliary devices (5), eg fans other equipment connected to

30 electric generator will stop working for a while.

The inertial block (8, 58) is preferably of a material with a

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high thermal conductivity, such as aluminum or copper, preferably, so that the minimum temperature between their faces is lost. It also has to be a material with a high thermal diffusivity factor, that is, it has to have a high density, such as aluminum or copper, preferably. It also has to have a low coefficient of thermal expansion and withstand high temperatures well, above 400 ° C.

The electric generator further comprises at least one heat sink (6, 56) that maintains the temperature of a cold face (3, 53) of the at least one thermoelectric module (4, 54) below a second predetermined temperature, being preferably this second predetermined temperature 50 ° C and dissipates heat to the environment through first fins (7, 57). When fans are activated, forced air circulates through them to increase heat transfer. This improves the performance of the at least one heat sink (6, 56), preferably of the heatpipe type, and allows more air to be heated out of the heating apparatus, that is, the heating capacity is increased.

To ensure that the at least one thermoelectric module (4, 54) experiences 20 the greatest temperature differential between its faces (2, 52, 3, 53), it is important to avoid thermal bridges in the method of securing at least one module thermoelectric (4, 54). For this, the thermoelectric generator comprises some fastening screws (11, 61). The thermoelectric modules (4, 54) must work at compression of about 200psi, so that the fastening screws (11, 25 61) have to be tightened by a torque wrench to adjust the torque

of tightening at the appropriate pressure. The fastening screws (11) comprise a thermal insulator (12, 62) that reduces the thermal bridge between said fastening screws (11.61) and the at least one thermoelectric modules (4, 54).

The thermoelectric generator comprises a thermal paste (not shown) arranged on both sides of the thermoelectric modules (4, 54). This pasta

reduces the thermal resistance of contact with the inertial block (8, 58) and the

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heat sink (6, 56) allowing the circulation of a higher heat flow and consequently greater power generation.

The thermoelectric generator comprises springs (10, 60) that press the inertial block (8, 58) against the collection wall (17, 67) so that the heat flows to the thermoelectric modules (4, 54). When the first predetermined is exceeded, the displacement device (9, 59) is stretched by separating the inertial block (8, 58) from the collection wall (17, 67) and the compression force of the springs (10, 60) is overcome ). Once the temperature has dropped by 10 below the first predetermined temperature, the device

displacement (9, 59) is retracted and the springs (10, 60) press the inertial block (8, 58) again with the pickup wall (17, 67) and the cycle is repeated (in case it is returned to exceed the first predetermined temperature).

In a first preferred embodiment shown in Figures 1 to 4, in addition to the elements described above, the displacement device (9) comprises a thermal insulator (14) which has the function of reducing the contact temperature, avoiding that the device of

displacement (9) burns when it is working.

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In a second preferred embodiment shown in Figures 7 to 10, in addition to the elements described above, with the exception of the thermal insulator, the displacement device (59) is a thermoelectric actuator that regulates the distance between the collection wall ( 67) of the heating apparatus and the at least one thermoelectric module when the temperature on the hot face (52) of the at least one thermoelectric module (54) is equal to or greater than the first predetermined temperature.

In this case, and preferably, the thermoelectric generator comprises a control electronics of the PID type (differential integral proportional) that drives and regulates the electric linear actuator (59) by adjusting the distance between the

collection wall (67) of the heating apparatus and the at least one module

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thermoelectric (54) to maintain the hot face temperature (52) of at least one thermoelectric module (54) equal to the first predetermined temperature.

5 Thus, the thermoelectric generator is more efficient since the at least one thermoelectric module (54) works for a longer time at its optimum operating point and the electric linear actuator (59) works for less time, consuming less energy.

The first fins (57), in this second embodiment, are attached laterally to the heat sink (56), the electric linear actuator (59) being also attached to the first fins (57), so that when it leads to the separation of the at least one thermoelectric module (54) from the collection wall (67) of the heating apparatus, the force that has

15 that exercising the electric linear actuator (59) is minimized by taking advantage of the lever arm due to its lateral arrangement with respect to the heat sink (56) and consequently with respect to the at least one thermoelectric module (54) and the inertial block (58), so that although the inertial block (58) continues to make contact with one of the ends of the collection wall (67)

20 of the heating apparatus, the contact surface between the two (58, 67) is so small that it does not allow heat transfer by conduction to continue heating the inertial block (58). Thus, the energy consumed by the electric linear actuator (59) is also reduced.

The invention also relates to a heating apparatus (1) as shown in Figures 5 and 6 comprising at least one thermoelectric generator as described above for the first or second examples of preferred embodiment.

The heating apparatus (1) further comprises at least one auxiliary device (5) that is powered by the thermoelectric generator, being

preferably the auxiliary device (5) a fan.

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The control electronics convert the electricity generated in the thermoelectric generator to a suitable voltage of 12V or 5V to power the fans and other auxiliary devices (5) such as lighting, 5 sensors, charging of mobile devices ...

The thermoelectric generator comprises fastening screws (15, 65) with the collection wall (17, 67) that hold the electric generator to the heating apparatus where combustion takes place.

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The collection wall (67) of the heating apparatus comprises second fins (68) in the wall inside the heating apparatus, which makes it possible to increase the heat transfer from the heating apparatus to the collection wall ( 67) and consequently towards at least 15 a thermoelectric module (54). This allows the electric generator to always work at its most optimal and efficient point, which is precisely at the first predetermined temperature

Claims (14)

1. - Thermoelectric generator comprising at least one thermoelectric module (4, 54) arranged in direct or indirect contact with a wall 5 for collecting (17, 67) of a heating apparatus (1), characterized in that the at least one thermoelectric module (4, 54) is movable with respect to the collection wall (17, 67) of the heating apparatus (1 ) by means of a displacement device (9, 59) which carries out the separation of the at least one thermoelectric module (4, 54) from the collection wall (17, 67) of the heating apparatus (1) when a hot face (2, 52) of the at least one thermoelectric module (4, 54) is above a first predetermined temperature. 2. - Thermoelectric generator according to claim 1 characterized in that it comprises an inertial block (8, 58) that is in contact with the at minus a thermoelectric module (4, 54) and which acts as a thermal reservoir that accumulates thermal energy when the separation of the at least one thermoelectric module (4, 54) from the collection wall (17, 67) of the apparatus of heating (1), so that the at least one thermoelectric module 20 (4, 54) is arranged in indirect contact with the collection wall (17, 67) of the heating apparatus (1) through the inertial block (8 , 58). 3. - Thermoelectric generator according to any of the claims 25 above characterized in that it also comprises at least one heat sink heat (6, 56) that maintains the temperature of a cold face (3, 53) of the at least one thermoelectric module (4, 54) below a second predetermined temperature. 30 4. Thermoelectric generator according to any of the claims anterior characterized in that it comprises first fins (7, 57) attached to the heatsink. 5. - Thermoelectric generator according to any of the preceding claims characterized in that the thermoelectric generator comprises fastening screws (11, 61) of the at least one thermoelectric modules (4, 54). 5 6. - Thermoelectric generator according to claim 5 characterized in that the clamping screws (11, 61) work under compression, preferably 200psi. 10. Thermoelectric generator according to any of claims 5 or 6 characterized in that the fastening screws (11, 61) comprise a thermal insulator (12, 62) that reduces the thermal bridge between said fastening screws (11.61) and the at least one thermoelectric modules (4, 54). 15. Thermoelectric generator according to claims 2 and 3 characterized by comprising a thermal paste disposed on both sides of the thermoelectric modules to reduce the thermal resistance of contact with the inertial block (8, 58) and the heat sink (6, 56). 20. Thermoelectric generator according to claim 2 characterized in that It comprises springs (10, 60) that press the inertial block (8, 58) against the collection wall (17, 67) so that heat flows to at least one thermoelectric module (4, 54). 10. Thermoelectric generator according to any of claims 5 or 6 characterized in that it comprises fastening screws (15, 65) with the collection wall (17, 67) that hold the electric generator to the heating apparatus (1) where combustion is carried out. 30 11. Thermoelectric generator according to claim 2 characterized in that The inertial block (8, 58) is made of aluminum or copper. 12. Thermoelectric generator according to any of the claims above characterized in that the displacement device (9) is a thermo-mechanical linear actuator. 13. 13. Thermoelectric generator according to any of claims 1 to 11 characterized in that the displacement device (9, 59) is an electric linear actuator. 14. - Thermoelectric generator according to claim 13 characterized in that it comprises a temperature sensor arranged in the thermoelectric module (4, 54) for a control electronics to give an actuation setpoint to the electric linear actuator. 15. - Thermoelectric generator according to any of the claims Previous 15 characterized in that the displacement device (9) It comprises a thermal insulator (14). 16. - Thermoelectric generator according to claim 14 characterized in that the displacement device (59) is a thermoelectric actuator which 20 regulates the distance between the collection wall (67) of the heating apparatus and the at least one thermoelectric module when the temperature on the hot face (52) of the at least one thermoelectric module (54) is equal to or greater than the first temperature default 17. Thermoelectric generator according to claim 16 characterized in that The control electronics are of the integral integral proportional type, PID, that drives and regulates the electric linear actuator by adjusting the distance between the collection wall (67) of the heating apparatus and the at least one thermoelectric module (54) to maintain the temperature on the hot face (52) of at least 30 a thermoelectric module (54) equal to the first predetermined temperature. 18. - Thermoelectric generator according to claim 17 characterized in that the first fins (57) are laterally connected to the heat sink (56), the electric linear actuator (59) also being connected to the first fins (57), so that when you carry out the separation of the at least one 5 thermoelectric module (54) of the collection wall (67) of the heating apparatus, the inertial block (58) continues to make contact with one of the ends of the collection wall (67) of the heating apparatus. 19. - Heating apparatus (1) comprising at least one generator of any one of the preceding claims. 20. - Heating apparatus (1) according to claim 19 characterized in that it further comprises at least one auxiliary device (5) that is powered by the thermoelectric generator. fifteen 21. - Heating apparatus (1) according to claim 20 characterized in that the auxiliary device (5) is a fan. 22. - Heating apparatus (1) according to any of claims 19 to 20 21 characterized in that the collection wall (67) of the heating apparatus It comprises second fins (68) in the wall inside the heating apparatus.