ES2921483B2 - Thermoelectric module for the use of residual heat and industrial process monitoring system - Google Patents

Description

DESCRIPTION

Thermoelectric module for the use of residual heat and industrial process monitoring system

Technical sector of the invention

The present invention refers to a thermoelectric module for the use of residual heat, specially adapted to be installed on pipes or industrial surfaces, which act as a heat source. Thus, a new industrial process monitoring system for predictive maintenance is also presented, taking advantage of residual heat through the aforementioned thermoelectric module.

Background of the invention

For many years, fossil fuels have been abused as a means of obtaining energy, giving rise to severe consequences such as global warming of the world we inhabit. Fossil fuels are finite and their obtaining, extraction, transformation or exploitation generate, among other drawbacks, emissions of gases that are harmful to the environment and living beings.

Currently, human beings are becoming more and more aware of the need to protect the environment, researching and developing other energy sources, such as renewable energy sources. In addition to, for example, using energy in a more intelligent and sustainable way, avoiding wasteful consumption, making equipment more efficient to consume less; These types of renewable sources such as solar energy, wind power, geothermal energy and others are beginning to be implemented.

Among this type of development to optimize energy resources, one of the emerging technologies, today, and which is addressed by the present invention is thermoelectricity. As its name indicates, thermoelectricity is a branch of physics in which the direct transformation of thermal energy to electrical energy or vice versa is studied. Although it was discovered years ago, more than 180 years ago, now more interest is regaining its application and exploitation for the optimization of energy resources.

Mainly, the interest of thermoelectricity is due to its ability to convert residual heat into electrical energy that can be a source of energy for other uses. Residual heat is the one that is wasted from some industrial process or not and that is not used later, but is emitted into the environment. It has a lower a priori utility than the original energy source and can be considered low energy level heat and this is where thermoelectricity is considered as a promising technology to recover lost heat and increase performance.

The pioneer of thermoelectricity was the German scientist Thomas Johann Seebeck (1770-1831). In 1822 he summarized the results of his experiments in the article "The Magnetic Polarization of Metal and Ores Produced by Temperature Difference". Seebeck experimented with how a compass needle deviated if it was placed in the vicinity of a closed circuit formed by two conductors when one of its junctions was heated.

He mistakenly concluded that the interaction was due to a magnetic phenomenon, and continuing with this belief, he attempted to relate the earth's magnetism to the difference in temperature between the equator and the poles. Although he failed to define the effect correctly, Seebeck investigated the phenomenon in a large number of materials, including some of what we know today as semiconductors.

Years later, the Peltier effect was discovered in 1834, this is the complementary effect of the Seebeck effect. This effect occurs when a current passes through a circuit with two different conductors; Depending on the direction of the current, the junction of the two conductors can release heat or absorb heat. This effect was discovered by the French physicist Jean Charles Athanase Peltier (1785-1845). Like Seebeck, Peltier misinterpreted the results of his research as he failed to assess the foundations of his observations or to relate the effect to Seebeck's findings. Only in 1838 did Emily Lenz (1804-1865) prove that the Peltier effect was an autonomous physical phenomenon, which consisted of releasing or absorbing additional heat at the junction of the conductors when a current passed through them and demonstrated it by freezing water and returning to melt the ice by reversing the direction of the current.

Twenty years later, William Thomson wrote a comprehensive explanation of the Seebeck and Peltier effects and described the relationship between them. In addition, he predicted the existence of a third thermoelectric effect. the Thomson effect, which he sequenced by observing experimentally.

This effect relates to the heating or cooling of a homogeneous conductor in the presence of a temperature gradient when a current passes through it.

The discoveries triggered the development of a new field of engineering, thermal energy engineering, which studies the processes of conversion of thermal energy into electrical energy (Seebeck Effect) and thermoelectric heating and cooling (Peltier Effect).

In the middle of the 20th century, thermoelectricity reappeared due to the discovery of synthetic semiconductors with high Seebeck coefficients. But semiconductors weren't getting any better than metals, so interest waned. It was not until the 50s, where compound semiconductors were obtained, obtaining thermoelectric improvements and stimulating possible military applications.

In the early 1960s, space exploration, as well as the exploration of terrestrial resources in hostile places, required autonomous electrical power sources. Thermoelectricity is presented as an ideal technology for these cases, since the absence of moving parts, its reliability and its silent operation offset its relatively high cost and low efficiency. Therefore, radioisotope-powered generators were developed for the Apollo space program and for communications with the moon, from which most of the materials used in most current commercial generators would derive. At present there has been a great increase in thermoelectric research due to the search for energy alternatives for scale production. Today thermoelectric generators (known as TEGs for its acronym in English: Thermo Electric Generator) are manufactured with various semiconductor materials and with varied results.

A thermoelectric generator is made up of one or several thermoelectric modules. Thermoelectric modules or Peltier cells (trade name) directly convert heat into electricity. Heat induces the circulation of an electrical current by flowing from a heat source through the thermoelectric generator (thermogenerator).

To generate electricity through the thermoelectric effect, a Peltier cell and a temperature differential between both sides of it are needed. Since the flow of current it also generates heat, the hot and cold sources have to continually add and dissipate heat to maintain that difference.

A Peltier cell is made up of two ceramic plates that serve as the base of the P-type and N-type thermocouples or thermocouples made of semiconductor materials, it also provides mechanical stability and serves as an electrical insulator.

A conventional module is made up of several thermoelectric pairs (semiconductor elements with P and N doping), electrically connected in series and thermally in parallel where there are free holes, both semiconductors being connected through metal junctions of high electrical conductivity. A Peltier cell is made up of 100 and 600 thermoelements.

These modules are silent, have no moving parts and do not require maintenance. In addition, its size and weight are low and it can be used for a wide range of temperatures. However, they have an important disadvantage, their low efficiency.

This efficiency is linked to the semiconductor materials that form the thermoelectric couples and is currently being investigated for its improvement, but the process is slow. Therefore, in order to increase performance, the heat exchange systems that are located on both sides of the cell must be optimized to increase the electrical power generated. This is achieved in part as the temperature of the cold or heat source is similar to the temperatures of the sources of origin.

Taking into account the current state of the art, the objective of the present invention is to achieve a thermoelectric module that is capable of generating enough energy to power electronic devices or industrial sensors, taking advantage of the residual heat of the machine or process itself that is to be monitored.

Another objective of the present invention is to offer a new system for monitoring industrial processes for predictive maintenance, taking advantage of residual heat through the thermoelectric module described in the present invention.

Explanation of the invention

In order to provide a technical solution for the use of industrial heat, especially for industrial pipes, and the growing need to monitor various parameters of the operation of machines and processes in the industry; A thermoelectric module for the use of residual heat is disclosed, specially adapted to be installed on pipes, conduits and industrial surfaces, which comprises at least one heat capture means, one power generation means and one heat dissipation means. heat. That with the associated electronics that will be presented later allows this monitoring without the need for wiring or batteries.

In essence, the thermoelectric module is characterized in that the capture means comprise at least one heat collector essentially formed by a prismatic piece of a thermal conductive material adapted to make contact on one of its faces with the surface of a heat source external to the module. thermoelectric, such as an industrial pipe, the power generation means, adapted for the transformation of heat into electrical energy, comprise at least one thermoelectric generator whose lower base is in contact with the heat collector, the heat dissipation means comprise at least one heatsink with a plurality of fins to absorb the maximum possible heat that comes from the thermoelectric generator to which it is coupled, and is characterized in that it is also provided with structural and thermal insulation means. Said structural and thermal insulation means comprise a structural base of an essentially plastic material that provides the assembly with mechanical rigidity to act as pressure to the thermoelectric generator together with the heatsink and which has at least one opening through which the heat collector is susceptible to contact with the surface of the heat source; and at least one thermal joint between the heatsink and the structural base provided with at least one hole through which the thermoelectric generator is inserted through it to contact the heat collector.

Advantageously, by placing said thermoelectric module on a pipe or surface, it is possible to take advantage of its residual heat for the generation of electrical energy that can be used in other devices. Through this configuration, it is achieved that, although the heat collection surface is small compared to the surface of the heat source, such as an industrial pipe, having the structural base protects the heat sink from the radiant heat of the source of heat. heat and in turn works as a structural element that fixes all the components of the thermoelectric generation process, all of which increases the energy efficiency of the whole.

Likewise, by means of this thermal joint, a secure tightness is achieved once the thermoelectric generator has been assembled. In addition to working as a sealing element, it has two more functions. On the one hand, it must prevent the heat coming from the structural base from reaching the heatsink and contaminating it, worsening its operation; and, on the other hand, it has the objective of framing the assembly of said thermoelectric generator and fixing its position with the sensor.

According to another characteristic of the invention, the thermoelectric module is characterized in that the heat collector is provided with at least one perimeter rim to rest on the structural base. Thanks to this perimeter rim, when pressure is applied to the thermoelectric generator through the structural base and the dissipator, it is prevented from being expelled by the applied force; that is, it works as well as support as a stop. According to a preferred embodiment of the invention, the thermoelectric module is characterized in that the thermoelectric generator has at least one Peltier cell. Said Peltier cell achieves from a temperature differential that is generated between its opposite surfaces, the one that contacts the collector and the one that contacts the heatsink, a thermal energy that can be converted into electrical energy.

According to another feature of the invention, the structural base is provided with multiple ribs. As previously mentioned, an important component of the invention is the structural base, since its objective is to provide mechanical rigidity to act as a pressure system for the electric generator together with the heatsink. But on the other hand, it not only acts as a structural element, but also has the mission of acting as thermal insulation as also indicated above, which is why a design with ribs is made, on the one hand, to support the efforts both of pressure to the thermoelectric generator as well as the pressure at the time of assembly in the heat source and on the other, to create hollow areas with the presence of air to use these spaces as thermal insulation against radiation and convection.

In a preferred embodiment of the invention, the thermoelectric module is characterized in that it also comprises at least two screws inserted through the lower part of the structural base and that have stops and Belleville-type washers that allow the depth to be controlled, acting as a spring and applying the force required so that the thermoelectric generator remains attached and in contact with the heatsink at the pressure torque suitable for its correct operation. Advantageously, by means of this pressure screw it is possible to It manages to reduce the surface roughness between the faces of the thermoelectric generator and the collector and heatsink, respectively, improving the heat transfer of the module.

According to another feature of the invention, the thermoelectric module is characterized in that it comprises an electronic box capable of housing inside the electronics responsible for managing the electrical energy from the thermoelectric generator.

According to another aspect of the invention, with the aim of providing a solution for monitoring industrial processes for predictive maintenance taking advantage of residual heat, a system characterized in that it comprises at least one thermoelectric module such as the one presented in this same section with previously, which generates enough energy to power electronic devices or industrial sensors of the machine itself that is to be monitored.

Advantageously, with this system of the invention it is possible to monitor any machine without input of energy by using the residual heat from the machine itself or other residual sources in the environment where said system is applied.

According to another characteristic of the invention, the system is characterized in that it also comprises an IoT node to communicate and transmit the data obtained from the thermoelectric module, electronic device or industrial sensor of the machine itself that is being monitored.

In addition, according to a preferred embodiment, it is provided that the system comprises an analog power supply control of the SoC (The acronym SoC refers throughout this report to the Anglo-Saxon term 'System on a Chip', that is, a chip integrated by multiple components that, together, make up a complete system), connecting or disconnecting the system voltage to charge a super capacity even though the generated energy is very low, such as less than the consumption of low consumption operation. Advantageously, a very interesting solution for predictive maintenance in industrial environments is achieved through this system, without specifying additional energy consumption.

Brief description of the drawings

In order to complete the description that is being made and in order to facilitate the understanding of the characteristics of the invention, a set of drawings is attached to the present specification in which, by way of example and non-limitation, a mode of realization of the thermoelectric module and the system of the invention. Specifically, the following is represented: Fig. 1 is a schematic exploded view of the thermoelectric module according to the invention; Fig. 2 is a schematic and perspective view of the thermoelectric module according to the invention;

Fig. 3 is a schematic and perspective view according to a bottom view of the thermoelectric module of Fig. 2;

Fig. 4 is a schematic side view of the thermoelectric module of Fig. 2;

Fig. 5 is a schematic and perspective view of the thermoelectric module of Fig. 2 with the loT module of the system according to the invention;

Fig. 6 is a schematic view of the system according to the invention;

Fig. 7 is both schematic views in perspective and in section of the heat collector of the thermoelectric module according to the invention;

Fig. 8 are two perspective views from above, below and in section of the structural base of the thermoelectric module according to the invention;

Fig. 9 is a partial schematic view of the structural base of Fig. 8;

Fig. 10 is a partial schematic view of the structural base of Fig. 8;

Fig. 11 are respective schematic views of the thermal joint of the thermoelectric module according to the invention;

Fig. 12 are respective schematic views of the Peltier cell that make up the thermoelectric generator of the thermoelectric module according to the invention;

Fig. 13 are respective schematic perspective and partial views installed in the structural base of the thermal joint of the electronic box of the thermoelectric module according to the invention;

Fig. 14 are respective schematic views in perspective according to two points of view of the electronic box of the thermoelectric module according to the invention;

the Figs. 15 and 16 are, respectively, perspective schematic views of a screw according to the invention and the three screws installed in the thermoelectric module of the exemplary embodiment according to the invention;

the Figs. 17a, 17b, 17c, 17d, 17e and 17f are respective schematic views that facilitate the understanding of how the capture means and the generation means of the thermoelectric module according to the invention are mounted on the structural base;

the Figs. 18a, 18b and 18c are schematic views of the sensors, the sensors with the Peltier cells and the assembly with the heat sink, respectively; and

the Figs. 19a and 19b are respective views of the electrical operation and block diagram of the control system.

Detailed description of the drawings

Fig. 1 presents a thermoelectric module 1 according to the invention for the use of residual heat, specially adapted to be installed on industrial pipes. To facilitate the understanding and identification of the different parts that make up this new thermoelectric module 1, each part has been drawn schematically and separated. As can be seen, the thermoelectric module 1 comprises means for collecting heat 2, means for generating energy 4 and means for dissipating heat 5.

Specifically, in this thermoelectric module 1, it can be seen that the heat collection means 2 comprise two heat collectors 21 essentially each one formed by a prismatic piece of a thermal conductive material, such as a metallic material, adapted to contact on one of its faces, the lower flat surface 24, with the surface 35 of a heat source 3 (in Figs. 4, 6 and 18c this heat source 3 is represented).

In addition, the power generation means 4 of the aforementioned thermoelectric module 1 and which are adapted for the transformation of heat into electrical energy, comprise two thermoelectric generators 41 whose lower base 42 is in contact with the collector 21 (Figs. 16, 18b and 18c).

It can also be seen in the thermoelectric module 1 represented in Fig. 1 that the heat dissipation means 5 comprise a heatsink 51 with a plurality of fins 52 to absorb the maximum possible heat coming from the thermoelectric generator 41 to which it is coupled.

In addition to said heat collection means 2, power generation means 4 and heat dissipation means 5, the thermoelectric module 1 is also provided with structural and thermal insulation means (60) that comprise a structural base 6 made of an essentially plastic material that provides the set (of components of the mentioned module) with mechanical rigidity to act as pressure to the thermoelectric generator 41 together with the heatsink 51 and which has two openings 61 through which the heat collector 21 is susceptible contacting the surface 35 of the heat source 3.

The component called heat collector 21 of the heat capture means 2 has the objective of capturing the maximum heat flux that occurs in contact with the heat source 3. This component allows heat transfer by conduction from the heat source 3 up to the upper flat surface 23 on which the lower base 42 of the thermoelectric generator 41 rests. In this example, the thermoelectric module 1 is configured with two heat collectors 21 and two thermoelectric generators 41. Each heat collector 21 consists of a piece of metallic material, such as an aluminum-based alloy, because a high conduction heat transfer coefficient is needed and metallic materials have this highest value. In addition, this piece that forms the heat collector 21 has two wings 25 which are used to fix the piece to the structural base 6 through two screws 26 for plastic. On the other hand, as can also be seen in other figures such as Figs. 7, 16, 17c, 18a, 18b and 18c, the heat collector 21 has a perimeter rim 22 that serves to rest on and function as a stop on the structural base 6 and prevent it from applying pressure to the thermoelectric generators 41 through the aforementioned structural base 6 and the dissipator 51, these are expelled by the applied force. This piece that forms the heat collector 21 has a flat surface on both faces 23, 24 and this is to facilitate assembly and heat transmission on flat surfaces. In any case, it is foreseen that in the case of heat sources 3 with round tubular surfaces, there will be two holes 27 (Figs. 3, 7 and 16) for the coupling of adapters, not represented, to this type of surfaces. In addition, and in order to guarantee tightness once the sensors 21 have been assembled, they have an O-ring 28 of the high-temperature type, made, for example, of an inorganic polymer such as silicone. Said gasket 28 is attached to the lower part of the perimeter rim 22 as can be seen in Fig. 7. The O-ring acts as a static seal for the triangular groove where it rests.

The component called thermoelectric generator 41 of the power generation means 4, which is provided with two Peltier cells 41', has the objective of converting thermal energy into electrical energy from the temperature differential that occurs between both surfaces of said cells. Peltier 41'. In other words, the Peltier effect will absorb heat from the hot side that is in contact with the heat collector 21 and will dissipate it through the cold side that is in contact with the heat sink 51. This heat flow will depend on the type of cell chosen.

In a manner known per se, and as briefly described in the background of the present invention, this heat flow produces a Joule effect and combined with the effect Thomson, the Seebeck effect originates, appearing an electromotive force that generates an electrical current and therefore the electrical energy that is intended from the residual heat of this heat source 3. For the example represented here, a Peltier cell 41' has been selected equipped with of two Al203 ceramic plates, BiTe3 material pellets, aluminum conductor, two black and red Teflon cables, and perimeter silicone as a sealing gasket. The total number of thermocouples present in this thermoelectric generator 41 is a quantity of 199 thermocouples (398 pellets).

The component called heat sink 51 of the heat dissipation means 5 has the objective of absorbing the maximum possible heat that comes from the source with the highest temperature, which in this case is the hot surface of the thermoelectric generator 41, that is, the upper surface of the Peltier cells 41', and transfer this heat to the environment, which in this case is the air or industrial atmosphere 34. To make this process possible, it is necessary for the material of the heatsink 51 to have good thermal conduction and the existence of a plurality of fins 52, in this case straight, although they could be corrugated to increase the contact surface with the environment, allowing faster removal of excess heat by means of natural convection. The heatsink 51 used in the example described here is designed to have a horizontal orientation or with the fins vertically considering that the fins must have the same direction as that of the air flow. This heatsink 51 is provided to have three threaded holes to exert pressure on the Peltier cells 41'. It is contemplated that it can be manufactured from an aluminum alloy and be naturally anodized for surface protection against adverse conditions.

All these components are supported by the structural base 6 which, as previously mentioned, provides the assembly with mechanical rigidity to act as pressure to the Peltier cells 41' together with the heatsink 51. On the other hand, it not only acts as a structural element, it also has the mission of acting as thermal insulation. This is because the heat source 3 emits heat in the form of radiation and convection and could contaminate the heatsink 51, increasing its temperature and causing thermal collapse if nothing is done. That is why this component is installed, to act as a screen avoiding heat by radiation and convection as this structural base 6 is made of a plastic material. Although this does not prevent the component from heating up, in fact, it increases its temperature, on the one hand, due to the heat emitted by the source and, on the other, due to the heat transfer by conduction that comes from the heat collectors 21. All These situations cause its temperature to increase, but not considerably since a thermal joint 7 is installed on top of the structural base 6, which also acts as an insulator. Therefore, the greatest thermal flux by conduction is produced by the heat collector 21, the thermoelectric generators 41 or Peltier cells 41' and the heatsink 51, as can be seen in Fig. 18c. If you look at Fig. 8, you can see the lower part of the structural base 6. Being a plastic, this component can be manufactured by means of injection, so the part should not have very thick areas. It is for this reason that a design with ribs 62 is made, on the one hand, to support both the pressure stresses of the thermoelectric generators 41 or Peltier cells 41' and the pressure at the time of assembly in the heat source 3 and on the other, create hollow areas with the presence of air to use these spaces as thermal insulation against radiation and convection. Air, as is well known, is one of the best insulators in the world and this helps ensure that the thermal path is only through the collector and the cells, and does not increase the energy that the heatsink has to dissipate, making the temperature that reaches the component has a greater descent. The plastic material that has been used in the example has three holes for the insertion of three screws 8 that exert pressure on the thermoelectric generators 41 or Peltier cells 41'. It is further provided, as can be seen in Figs. 8, 9 and 10, which has a hole for fixing an electronic box 9 with two plastic screws, not shown, and two holes for each heat collector 21. On the sides, the aforementioned structural base 6 has a geometry to easily insert warning labels with a square hole and a slot with two holes for the insertion of two screws in case the installation is carried out on a flat surface or the flat groove for the assembly of a metallic clamp for circular duct.

The thermal joint 7, represented in Fig. 11, has the purpose of fulfilling three objectives, the first and most important is to act as a sealing joint between the heat sink 51 and the structural base 6 in order to prevent it from water, humidity or dust can leak into the interior of the equipment and damage all electrical components such as the thermoelectric generator 41 or Peltier cell 41' or the same electronics that are housed inside the electronic box 9. If the sealing is not produces, there is a very high probability that there are failures due to short circuit and oxidation in the union of electrical components. That is why this gasket is made of an elastomeric material with the ability to deform when a pressure force is applied to it and its own deformation adapts to the surface in contact, resulting in no element being able to leak through it. The second objective that this piece must fulfill is to act as thermal insulation. Being in contact with the structural base 6 and in the same way said structural base 6 receives the heat from the heat source 3, it causes heat transfer by conduction. Consequently, a material of the plastic-elastomeric type is chosen, and it also has a low thermal transfer coefficient by conduction, withstanding up to 200°C continuously and 250°C in short periods of operation. Therefore, the union of two insulating components, such as the structural base 6 and the thermal joint 7, are sufficient to prevent residual heat from reaching the heat sink 51 and causing a decrease in its thermal performance. And, as a third objective, it has the purpose of acting as a framing element when mounting the thermoelectric generators 41 (Peltier cells 41') on the heat collector 21. This means that the Peltier cells 41' (in the represented example of the figures) are mounted on the square geometry present in the piece in the form of a hole, preventing it from moving when exerting pressure through the tightening screws 8. In addition, it has a groove through which their respective cables are directed towards a hole that leads to the electronic box 9.

In a similar way to the thermal joint 7, it is foreseen that the thermoelectric module 1 has a second thermal joint, the thermal joint 77 of the electronic box 9, whose objective is to act as a sealing element against atmospheric agents and as a sealing element. thermal insulation to avoid failures due to short circuits and/or oxidation of the electrical components that make up the electronic box 9.

The electronic box 9, whose mission is to house inside the electronics responsible for managing the electrical energy from the thermoelectric generator 41. The power electronics are made up of a DC/DC converter with a Start-up voltage of 0.225V, and an MPPC so that the input voltage does not drop below 0.4V. And an output voltage of 5V. Converters with higher and lower start-up voltages, with MPPT, and with adjustable upper and lower outputs have been used in other variants also included in the present invention. Given that the system requires or may require higher energies for its operation than those generated by the thermoelectric generator 41, the energy accumulates in a super capacity (usually 5F). The accumulated energy depends on the voltage and capacity, more voltage implies being able to use a lower capacity. Given that at low temperatures the energy generated is very low, in the order of 1mW, it is interesting that the system is turned off until it has enough energy to carry out a complete work cycle (from acquisition to sending the data). The power control part is in charge of ensuring that until enough energy has been accumulated, the monitoring part does not consume anything (it has no voltage), cutting off the power. This has two advantages: the first is that since there is no consumption by the electronics, all the energy generated accumulates in the capacity. The second is that it prevents erroneous operations due to a slow rise in voltage, or unstable operation due to which consumption increases, wrongly using the Accumulated energy. The system generates two programmable limits, the one on (normally 4.5V), and the one off, which depends on the function of the device (normally 3.7V). These minimum turn-on voltages are represented in Fig. 19a and in Fig. 19b the operation according to stages X3, X1, X2 that feed the SoC. The programming of these voltages depends on two resistors. These on and off values will depend on the operating voltage of the system, typically 3.3V, 2.5V or 1.8V. Being a system that generates its own energy and does not depend on a battery, it allows use with Edge-Computing algorithms without affecting the life of the device. What allows certain analyzes without the need to send a lot of data with the saving of communications, and avoiding a saturation of the radioelectric spectrum.

As has been shown, the pressure that exists between all the components is vital for proper functioning and maximum optimization of the energy performance of the thermoelectric module 1. Thus, the pressure system of the thermoelectric generator 41 is described below, in concrete for the 41' Peltier cells, which in this example consists of three special 8 screws that facilitate installation and reduce assembly time. This system is made up of machine screws 8 and two washers 82 as can be seen in Fig. 16. Each screw 8 in the example is made of steel and has a pin diameter of 6mm and a thread of M5. This makes it possible to create a stop 81 at the end of the pin that prevents further threading.

In the case of the system, the stop 81 prevents further screwing into the heatsink 51 and applying more force than is due. Peltier 41' cells need a pressure torque to reduce surface roughness, so it is recommended to use a pressure force of 1MPa to 1.2Mpa per Peltier 41' cell, in this case. From the dimensions of the Peltier cells 41' and the pressure, the force that must be applied to the screws 8 can be determined. In order to ensure said force, special washers 82 called Belleville are used that exert constant pressure on the surface support. Said washers 82, Belleville type, have a concave shape that allows applying a deformation and obtaining a residual elastic force. Depending on the force required, more than one washer 82 can be combined in the same direction to add forces.

By means of this thermoelectric module 1, according to the invention, an industrial process monitoring system for predictive maintenance is configured, taking advantage of residual heat as can be seen in the example represented in Fig 5. This system comprises the thermoelectric module 1, an IoT node 10 and the sensor (vibration and/or temperature). That is to say, the system by means of the aforementioned thermoelectric module 1 is capable of generating enough energy to power electronic devices 11, such as industrial sensors of the machine itself that is to be monitored (see Fig. 6).

At a functional level, the system of the represented example has two 41' Peltier cells per generation unit, which means that the larger the surface area, the energy generation that can be used will be. The thermoelectric module 1 follows the operating process of this type of energy transformation: collection, generation and dissipation. As has been presented previously, the components that will be located in each of them have been studied and calculated to obtain the best possible performance.

In the collection process, the thermoelectric module 1 will capture the greatest residual heat flux by contact with the surface emitted by a heat source 3 through the heat collection means 2. In the thermoelectric module 1 of this example there are two collectors 21 for two Peltier 41' cells that are located on the surface with the geometry of the Peltier 41' cell of 40x4Omm. The collected heat that passes through the collector 21 reaches one of the Peltier cells 41' (Thot, hot temperature) and then, by causing a thermal differential on the rear face (Tcold, cold temperature), it begins to generate electrical energy. . This cell, such as the TGM-199-1.4-3.2 from the manufacturer Kryotherm, is capable of generating 5.9W of electrical power with a temperature differential between faces of 170°C with a maximum working temperature of 200°C. The thermal differential on the Tcold face of the Peltier cell 41' is caused by a heat exchanger or heat sink 51 with straight fins 52 of the passive type. This component extracts the heat that passes through the Peltier cell 41' and dissipates it through its fins 52 in the form of radiation or is absorbed by the surrounding fluid through convection (this fluid in this case is the air of the atmosphere).

industry where said system is installed). This dissipated heat causes the surface Tcold of the Peltier cell 41', which is in contact with the heatsink 51, to cool down, causing a temperature differential between the surfaces of said Peltier cell 41'. Therefore, the Peltier cell 41' remains as a 'sandwich' between the contact sensor 21 and the finned heatsink 51 52 as can be seen in Figs. 1,2 and 3.

The collection surface by the collectors 21 is small compared to the surface of the heat source 3, this causes the heat emitted by the source to be absorbed by the thermoelectric module 1 and causes a decrease in both thermal and electrical performance. . That is why, to avoid this situation, an insulating component is installed to protect the heat sink from the radiant heat of the heat source and, in turn, works as a structural element that fixes all the components of the thermoelectric generation process, that is, the aforementioned structural base 6 described above.

With this configuration, a durable product is achieved that is resistant to temporary wear in the work environment, specially intended for industrial environments. This resistance includes resistance to corrosion greater than 5 years of operating life, resistance to ultraviolet radiation greater than 5 years of operating life, resistance to chemical attacks greater than 5 years of operating life and watertightness against to humidity, water and dust with a 1P67 protection.

Through the combination of the structural base 6 and the different fixing elements, such as the screws 8, the thermoelectric module 1 of the invention is robust enough to resist blows without deforming or breaking, its fracture toughness is greater than 25Mpa mA0.5.

The idea of the inventors has always been to achieve a solution that is easy and quick to install in terms of time without complicated operating assemblies, and this has been achieved, as can be seen in this example in which the entire thermoelectric module 1 is solidly joined and so It only has to be fixed to the surface 35 of the heat source 3 and connected to the rest of the elements that make up the system, such as the sensors of the machine that is to be monitored. The product must remain fixed and static for its correct operation and for this reason it is anchored and/or fixed by means of tightening components in a manner known per se.

It has not been the purpose of this report to invest time in mentioning the exact measures of the thermoelectric module 1 or the system of the invention, but as can be deduced its dimensions are discrete and do not interrupt internal processes due to size or functionality of the rest of the industrial installation. where the invention is installed. As a guide, the thermoelectric module 1 in the example has the following dimensions 220x100x100 mm.

To respect and not affect the rest of the regulations on occupational risk prevention of the industrial facility where it is installed, it is expected that both the thermoelectric module 1 and the elements that intervene with the system of the invention are correctly marked to avoid the interruption by third parties without authorization and cause unforeseen damage to both the equipment and the operator who could intervene, especially the hot surface will be clearly marked.

The shape of the thermoelectric module 1 assembly, as seen in the drawings, is approximately a prism. An attempt has been made to achieve an aesthetic that defines its shape through its functionality, taking into account that its aesthetics should not interrupt its performance.

At the electrical level, the generated energy does not affect the operation of the associated electronics, but it has an effect on the lack of energy accumulation, which will limit how often data acquisition can be done, and its pertinent analysis before sending them.

It can be deduced that, being mainly in industrial environments, temperature is a relevant aspect to take into account, thus the thermoelectric module 1 of the invention has been designed to be able to withstand working temperatures between -10°C and 50°C and temperatures operating between 50°C and 180°C.

In the same way that it was desired to offer a solution that was easy to install, it was also desired to achieve a solution that minimized the manufacturing process and the parts or components that make up the equipment. Although it is schematically in the drawings, combined with the present description, it can be noted that this objective has been achieved with a solution that has less than 20 pieces. In addition, the assembly and assembly of all the elements is reduced in complexity and time as all the details have been adjusted very well in this regard. At the level of direct manufacturing costs, it has been planned to use materials and elements available in the market without investing money in the creation of new materials or elements, but more time has been invested in a correct selection and triage of the most suitable materials. for these uses. Even so, some of the pieces are custom-made pieces, such as the structural base 6 and the collectors 21.

The thermoelectric module 1 of the example is part of a new system for monitoring industrial processes for predictive maintenance, taking advantage of residual heat, specifically the residual heat of the pipes 33 schematically represented in Figs.

4, 6 and 18c. This thermoelectric module 1 of this system obtains sufficient energy to power the electronic device 11 or industrial sensor of the machine itself that is to be monitored.

The system also comprises an IoT node 10 to communicate and transmit the data obtained from the thermoelectric module 1, electronic device 11 or industrial sensor of the machine itself that is being monitored.

Thus, a system for predictive maintenance is achieved that does not require additional energy for its operation. Sufficient energy is supplied only with the residual heat of the installation itself, such as that obtained from the surface of the pipes.

Finally, the inventors consider that the reader of the present description will be able to conclude that although an example has been described for an industrial environment and in fact it is basically the use that is considered to be more generalized, it is not ruled out that it can be used for non-industrial environments. industrial, in which essentially the same technical characteristics described here could be maintained.

Claims (9)

1. Thermoelectric module (1) for the use of residual heat, specially adapted to be installed on industrial pipes, comprising at least some heat capture means (2), energy generation means (4) and heat dissipation means (5), characterized in that - The heat collection means (2) comprise at least one heat collector (21) formed essentially by a prismatic piece of a thermal conductive material adapted to make contact on one of its faces with the surface of a heat source (3). external to the thermoelectric module (1); - the energy generation means (4), adapted for the transformation of heat into electrical energy, comprise at least one thermoelectric generator (41) whose lower base (42) is in contact with the heat collector (2); - The heat dissipation means (5) comprise at least one heatsink (51) with a plurality of fins (52) to absorb the maximum possible heat coming from the thermoelectric generator (41) to which it is coupled; and - because it is also provided with structural and thermal insulation means (60) that comprise: or a structural base (6) of an essentially plastic material that provides the set (of components of said module) with mechanical rigidity to act as pressure to the thermoelectric generator (41) together with the heatsink (51) and which has at least an opening (61) through which the heat collector (21) is capable of contacting the surface of the heat source (3); and or at least one thermal joint (7) between the heat sink (51) and the structural base (6), provided with at least one hole (71) through which the thermoelectric generator (41) is inserted through it to contact the heat collector (21) 2. Thermoelectric module (1) according to the preceding claim, characterized in that the heat collector (21) is provided with at least one perimeter rim (22) to rest on the structural base (6). Thermoelectric module (1) according to any one of the preceding claims, characterized in that the thermoelectric generator (41) is at least one Peltier cell (41'). Thermoelectric module (1) according to any one of the preceding claims, characterized in that the structural base (6) is provided with multiple ribs (62). 5. Thermoelectric module (1) according to any one of the preceding claims, characterized in that it further comprises at least two screws (8) inserted through the lower part of the structural base (6) and that have stops (81) and washers. (82) Belleville type that allow the depth to be controlled, acting as a spring and applying the force required so that the thermoelectric generator (41) remains attached and in contact with the heatsink (51) to the pressure torque suitable for its correct thermal operation . 6. Thermoelectric module (1) according to any one of the preceding claims, characterized in that it comprises an electronic box (9) capable of housing inside the electronics responsible for managing the electrical energy from the thermoelectric generator (41). 7. Industrial process monitoring system for predictive maintenance using residual heat, characterized in that it comprises at least one thermoelectric module (1) according to any one of claims 1 to 6 that generates enough energy to power electronic devices (11) or industrial sensors of the machine itself to be monitored. 8. Monitoring system according to the preceding claim, characterized in that it further comprises an IoT node (10) to communicate and transmit the data obtained from the thermoelectric module (1), electronic device (11) or industrial sensor of the machine itself being monitored. 9. Monitoring system according to the preceding claim, characterized in that it comprises an analog control of the SoC power supply, connecting or disconnecting the system voltage to load a supercapacitor even though the energy generated is very low, such as less than the consumption of low-frequency operation. consumption.