KR20210015158A - Heat-radiation structure using hygroscopic polymer and thermoelectric module having the same - Google Patents

Abstract

Disclosed is a heat dissipation structure, which includes a heat dissipation body and a hygroscopic polymer coupled to the heat dissipation body. Therefore, it is possible to implement a heat dissipation structure having excellent heat dissipation performance which exceeds the limit of the basic heat dissipation structure, by using the latent heat of vaporization of the hygroscopic polymer.

Description

A heat dissipation structure using a hygroscopic polymer and a thermoelectric module including the same {HEAT-RADIATION STRUCTURE USING HYGROSCOPIC POLYMER AND THERMOELECTRIC MODULE HAVING THE SAME}

The present invention relates to a heat radiation structure, and more particularly, to a heat radiation structure using a hygroscopic polymer and a thermoelectric module including the same.

Recently, electronic devices used in electric and electronic fields have a structure that generates a lot of heat due to the trend of being integrated with the miniaturization. Therefore, in order to prevent malfunction of the device due to heat and to secure long-term stability, a heat dissipation technology that rapidly dissipates heat is very necessary. A commonly used method uses a heat sink that allows the heat in the part to be quickly released by using a metal with high thermal conductivity for the heating part of the device. A commonly used heat sink has a form in which a metal having high thermal conductivity, such as aluminum or copper, is processed into a shape with a large surface area such as a fin shape to emit heat into the air. In order to increase cooling efficiency, this type of heat sink has a larger area than the normal heating part. This will increase the weight and volume of the entire product. Therefore, research on a new structure to maximize the heat dissipation performance in the same area is continuously being conducted.

Thermoelectric power generation devices are devices that utilize electromotive force generated when there is a temperature gradient between both ends of a thermoelectric module as a power source. Thermoelectric power generation devices are continuously expanding their application fields, such as power sources for deep space satellites that require long-term durability, power generation systems that recover and convert heat wasted from automobiles and industrial facilities into power, and wearable power generation systems using body temperature. Has become. In general, the power generated by a thermoelectric power generation system is defined as (SΔT) ² /4R _int , where S is the thermoelectric power of the thermoelectric power system (see Baek coefficient; V/K), T is the temperature difference between the low temperature and high temperature parts of the thermoelectric power system, R _int is the internal resistance of the thermoelectric power system.

When a thermoelectric power generation system is constructed using the body's body heat as a heat source, the high temperature part becomes the part where the thermoelectric power system contacts the skin (the lower part), and the low temperature part becomes the part where the atmosphere and the thermoelectric power system contact (the upper part). At this time, the temperature of the lower part depends on the thermal resistance of the skin and the interfacial thermal resistance of the thermoelectric power generation system. The temperature of the upper part depends on the heat resistance of the atmosphere and the upper part of the thermoelectric power generation system, and in order to keep this similar to the temperature of the atmosphere, a heat dissipation system having a structure such as a heat dissipation fin is used. In the case of a wearable thermoelectric power generation system, the heat dissipation system cannot be increased indefinitely because human wearability, etc. must be considered, and maximizing its heat transfer coefficient (Kcal/m ² h℃) in a limited size increases the temperature difference to increase power generation efficiency. It is the key to increasing it.

Researchers at Zhejiang University, China, proposed a heat dissipation structure in the form of a copper foam to improve the efficiency of thermoelectric power generation, but it was confirmed that the heat dissipation ability was lower than that of the existing fin-type heat sink. This is due to the fact that the convection phenomenon is suppressed in the copper porous body compared to the conventional fin type, and the heat exchange performance with the outside air is inferior.

In connection with the above technology, Korean Patent Publication No. 10-2016-0047843 discloses a device that uses a piece of a thermoelectric module and includes a charging unit, and includes an upper heat sink as a heat dissipation unit for improving the temperature difference. In the Korean Patent Publication No. 10-2017-0139366, in a wearable power generation system in which one surface of a thermoelectric module is attached to the skin of the human body, a flexible thermoelectric device that includes a heat-dissipating unit formed of a moisture-absorbing and heat generating material and a heat-dissipating unit that dissipates heat. System.

Patent Document 1: Korean Patent Application Publication No. 10-2016-0047843 Patent Document 2: Korean Patent Application Publication No. 10-2017-0139366

IShi, Yaoguang, et al. "Wearable Thermoelectric Generator With Copper Foam as the Heat Sink for Body Heat Harvesting." IEEE Access 6 (2018): 43602-43611.

The technical problem of the present invention is to provide a heat dissipation structure having improved heat dissipation performance.

Another object of the present invention is to provide a thermoelectric module including the heat dissipation structure.

The heat dissipation structure according to an embodiment for realizing the object of the present invention includes a heat dissipation body and a hygroscopic polymer combined with the heat dissipation body.

According to an embodiment, the heat dissipation body includes a fin array, and the hygroscopic polymer is disposed between adjacent fins.

According to an embodiment, the heat dissipation body has a metal porous structure.

According to an embodiment, the hygroscopic polymer is sodium polyacrylate, polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxyme?K cellulose ( cross-linked carboxymethylcellulose), polyvinyl alcohol copolymers, and cross-linked polyethylene oxide.

According to an embodiment, the cover member is coupled to the heat dissipation body to cover the hygroscopic polymer, and further includes a cover member having a ventilation portion connecting an inner space and an outer space in which the hygroscopic polymer is disposed.

According to one embodiment, the cover member comprises a fiber assembly.

According to an embodiment, the hygroscopic polymer has a powder form, a moisture absorption amount of 30 g/g or more, and a diameter of the powder of 150 μm to 850 μm.

The thermoelectric module according to an embodiment of the present invention includes a first substrate, a second substrate, a thermoelectric material portion disposed between the first substrate and the second substrate, and a thermoelectric material portion disposed between the first substrate and the thermoelectric material portion. A thermoelectric element including a first electrode and a second electrode disposed between the thermoelectric material portion and the second substrate; And a heat dissipation structure coupled to the first substrate of the thermoelectric element.

The wearable device according to an embodiment of the present invention includes the thermoelectric module, and the second substrate of the thermoelectric module is attached to the body or clothing.

According to embodiments of the present invention, a heat dissipation structure having excellent heat dissipation performance over the limit of the basic heat dissipation structure may be implemented by using the latent heat of vaporization (moisture absorption and vaporization in the air) of the hygroscopic polymer.

In addition, by adjusting the vaporization rate of the heat dissipation structure, it is possible to increase the heat dissipation holding time and adjust the heat dissipation performance according to the heat dissipation condition and target performance.

1 is a cross-sectional view illustrating a thermoelectric module according to an embodiment of the present invention.
2 is an enlarged cross-sectional view of a thermoelectric element unit of a thermoelectric module according to an embodiment of the present invention.
3 to 5 are cross-sectional views illustrating thermoelectric modules according to embodiments of the present invention.
6 is a digital photograph of the thermoelectric module of Example 1.
7 is a digital photograph of the thermoelectric module of Example 2.
8A and 8B are graphs showing a temperature difference between a lower substrate and an upper substrate of the thermoelectric module (Al Heat sink + SAP, Cu foam + SAP) of Examples 1 and 2;
9A and 9B are graphs showing the magnitudes of power and voltage output from the thermoelectric modules of Examples 1 and 2 measured.
10 is a graph showing a temperature difference of a thermoelectric module according to an embodiment of the present invention measured according to a pore size of a copper porous body.
11 is a graph showing the cooling performance of a thermoelectric module (metal heat sink + polymer absorbent resin) and a conventional metal heat sink according to an embodiment of the present invention according to humidity.

In the present application, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

The terms used in the present application are used only to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of being added.

1 is a cross-sectional view illustrating a thermoelectric module according to an embodiment of the present invention.

Referring to FIG. 1, the thermoelectric module includes a thermoelectric unit 200 and a heat dissipation unit 110. The thermoelectric part 200 includes a thermoelectric element. The thermoelectric unit 200 may generate power by a temperature difference between both ends of the thermoelectric element.

The radiating part 110 may be coupled to one surface of the thermoelectric part 200. The other surface of the thermoelectric part 200 may be adjacent to a heat source. For example, the thermoelectric module according to an embodiment of the present invention may be employed as a power source of a wearable device. Accordingly, the other surface of the thermoelectric part 200 may be adjacent to the body.

The heat dissipation unit 110 is connected to the thermoelectric unit 200 to emit heat from the thermoelectric unit 200, whereby the temperature of the end of the thermoelectric unit 200 adjacent to the heat dissipation unit 110 Can lower. In the thermoelectric element, since electromotive force is generated by the Seebeck effect of generating electricity according to a temperature difference between both ends of the device, power generation efficiency increases as the temperature difference between both ends increases.

According to an embodiment, the radiating part 110 may include a radiating body 112 and a hygroscopic polymer 114.

The heat dissipation body 112 may include a material having high thermal conductivity, such as a metal, and may have various known shapes in order to increase a heat dissipation effect. For example, the heat dissipation body 112 may include a metal such as copper, aluminum, nickel, or the like, a carbon-based material such as graphene, a carbon nanotube, or a ceramic. The radiating body 112 may include an array of a plurality of protrusions having a fin shape.

The hygroscopic polymer 114 absorbs moisture in the atmosphere. When the absorbed moisture is vaporized, heat from the radiating body 112 is taken away by latent heat. Therefore, it can exhibit a greater heat dissipation effect than simple convection or radiation.

For example, the hygroscopic polymer (114, super absorbent polymer), sodium polyacrylate (sodium polyacrylate), polyacrylamide copolymer (polyacrylamide copolymer), ethylene maleic anhydride copolymer (ethylene maleic anhydride copolymer), crosslinked carboxy Me?K cellulose (cross-linked carboxymethylcellulose), polyvinyl alcohol copolymers (polyvinyl alcohol copolymers), cross-linked polyethylene oxide (cross-linked polyethylene oxide), or a combination thereof.

According to an embodiment, the hygroscopic polymer 114 may be disposed between pins of the heat dissipating body 112. In FIG. 1, the hygroscopic polymer 114 is shown to have a particle shape, but embodiments of the present invention are not limited thereto, and the hygroscopic polymer 114 is a continuous covering the surface of the heat dissipating body 112 It may have a layered shape.

According to an embodiment, the hygroscopic polymer 114 may be adhered to the heat dissipating body 112. For example, the hygroscopic polymer 114 may be bonded to the heat dissipating body 112 by an appropriate adhesive such as glue. For example, after applying the adhesive to the heat dissipating body 112 entirely or partially through spraying, etc., by spraying a hygroscopic polymer in powder form, the heat dissipating body 112 combined with the hygroscopic polymer 114 can be formed. I can. When the hygroscopic polymer 114 absorbs moisture, its volume expands, so that it may adhere to the heat dissipating body 112.

For example, the moisture absorption amount of the hygroscopic polymer may be 30 g/g or more, and the diameter of the powder may be 150 μm to 850 μm.

The thermoelectric part 200 may include an array of thermoelectric elements.

2 is an enlarged cross-sectional view of a thermoelectric element unit of a thermoelectric module according to an embodiment of the present invention.

Referring to FIG. 2, the thermoelectric element unit 10 includes a first substrate 210, a second substrate 220 spaced apart from the first substrate, the first substrate 210 and the second substrate 220. It includes a first electrode 12 and a second electrode 14 disposed between and spaced apart from each other, and a thermoelectric material unit 16 disposed between the first electrode 12 and the second electrode 14. I can.

According to an embodiment, a first barrier layer 18a may be disposed between the first electrode 12 and the thermoelectric material unit 16. In addition, a second barrier layer 18b may be disposed between the second electrode 14 and the thermoelectric material unit 16. The barrier layers may protect the thermoelectric material part 16.

Each of the first substrate 210 and the second substrate 220 may include an electrically insulating material. For example, the first substrate 210 and the second substrate 220 may include alumina, sapphire, silicon, silicon nitride, silicon carbide, silicon aluminum carbide, quartz, polymer, and the like. The polymer may include polyimide, polyamide, polycarbonate, polystyrene, polyethylene terephthalate, polyacrylic resin, and the like.

In another embodiment, at least one of the first substrate 210 and the second substrate 220 may include a metal. For example, at least one of the first substrate 210 and the second substrate 220 may include copper, aluminum, nickel, or an alloy thereof. When the first substrate 210 or the second substrate 220 includes a metal, the first substrate 210 or the second substrate 220 and the first electrode 12 or the second electrode (14) A dielectric layer may be disposed between.

The first substrate 210 and the second substrate 220 may be made of the same material or may be made of different materials.

According to an embodiment, the thermoelectric element unit 10 may include a pair of thermoelectric material units 16. The thermoelectric material portions 16 may be doped in different types. For example, the thermoelectric element unit 10 may include a first thermoelectric material portion N doped with an n-type and a second thermoelectric material portion P doped with a p-type. One end of the first thermoelectric material portion N and the second thermoelectric material portion P may be electrically connected to the first electrode 12 in common. The other ends of the first thermoelectric material portion N and the second thermoelectric material portion P may be electrically connected to the second electrodes 14 spaced apart from each other, respectively.

For example, the thermoelectric material unit 16 may have a cylindrical shape or a polygonal column shape.

For example, the first electrode 12 may include a metal such as nickel (Ni), titanium (Ti), copper (Cu), platinum (Pt), gold (Au), silver (Ag), and the like. . In addition, the first electrode 12 may further include a metal compound such as NiP, TiN, ZnO, or the like. Each of these may be used alone or in combination. The second electrode 14 may include the same material or a different material as the first electrode.

The barrier layers may include a material different from that of the first electrode 12 or the second electrode 14. For example, the barrier layers are nickel (Ni), titanium (Ti), copper (Cu), platinum (Pt), gold (Au), silver (Ag), molybdenum (Mo), tin (Sn), zirconium Metals such as (Zr), niobium (Nb), tungsten (W), and the like, alloys thereof, or metal compounds thereof may be included. The metal compound may further include a metal compound such as NiP, TiN, or ZnO. According to an embodiment, the barrier layers may include a material having a lower coefficient of thermal expansion than a material constituting the first electrode 12. For example, when the first electrode 12 or the second electrode 14 includes copper, the barrier layers may include a material other than copper, and specifically, nickel, titanium, tin, Zirconium, alloys thereof, or metal compounds thereof.

According to an embodiment, the thermoelectric material unit 16 includes a thermoelectric material. For example, the thermoelectric material unit 16 may be a Bi (bismuth)-Te (tellurium) system, a Sb (antimony)-Te system, a Bi-Te-Se (selenium) system, a Bi-Te-Sb system, It may contain at least one of a two-element, three-element, and four-element material such as Bi-Sb-Te-Se. The thermoelectric material may be doped with an appropriate material. For example, selenium (Se) is added to Bi-Te to become N-type, or antimony (Sb) is added to become P-type. In addition to the above elements, SbI _3, Cu, Ag, CuCl N/P type implanted with impurities such as ₂ is also possible.

For example, the thermoelectric material may be represented by a formula of (Bi _1-x Sb _x ) ₂ (Te _1-y Se _y ) ₃ (0≤x≤1, 0≤y≤1). For example, the thermoelectric material may have a composition such as Bi ₂ Te ₃ , Sb ₂ Te ₃ , Bi _0.4 Sb _1.6 Te ₃ , Bi ₂ Te _2.7 Se _0.3 . However, embodiments of the present invention are not limited thereto, and various materials known in the field to which the present invention pertains may be used in the embodiments of the present invention.

3 to 5 are cross-sectional views illustrating thermoelectric modules according to embodiments of the present invention.

Referring to FIG. 3, the thermoelectric module includes a thermoelectric part 200 and a heat dissipating part 120. The heat dissipation part 120 may include a heat dissipation body 122 and a hygroscopic polymer 124.

According to an embodiment, the radiating body 122 may have a metal porous structure. For example, the porous heat radiation body 122 may be a metal foam. For example, the pore size of the porous structure may be 0.1mm to 0.5mm, preferably 0.2mm to 0.4mm.

For example, the porous heat dissipation body 122 may be manufactured by selective etching or anodizing.

In order to attach the porous radiating body 122 to the thermoelectric part 200, an adhesive having high thermal conductivity may be used. For example, silver paste, thermally conductive grease, reactive compound, adhesive film, etc. may be used.

A hygroscopic polymer 124 may be coupled to the porous radiating body 122. For example, after spraying glue with good adhesion on the porous heat dissipation body 122, a hygroscopic polymer 124 in powder form is sprayed to form a heat dissipation part 120 coupled to the thermoelectric part 200 can do.

Referring to FIG. 4, the heat dissipating body 122 having a porous structure combined with the hygroscopic polymer 124 may be disposed in the receiving portion 126.

For example, the receiving part 126 may have a box shape with an open surface.

In order to promote the convection phenomenon in the heat dissipating part 120, the receiving part 126 may have an opening 128 connecting the external space and the internal space. According to an embodiment, the opening 128 may be formed to penetrate the sidewall of the receiving portion.

Referring to FIG. 5, the heat dissipation body 112 including the fin array may be coupled to the cover member 116. The cover member 116 may cover the upper portion of the fin array and the hygroscopic polymer 114 disposed between the fin arrays.

According to an embodiment, the cover member 116 has a ventilation portion 118. Accordingly, compared to the structure in which the heat dissipation body 112 is opened, the vaporization rate of moisture adsorbed on the hygroscopic polymer 114 can be reduced. Therefore, it is possible to increase the heat dissipation holding time due to vaporization of moisture. In addition, by adjusting the number and size of the vents 118, the heat dissipation performance may be adjusted according to the heat dissipation condition and target performance. The ventilation part 118 may have various shapes such as holes and slits.

The shape of the cover member 116 is not limited to the illustrated one, and may have a form of a fiber aggregate such as a nonwoven fabric or a knitted fabric.

According to embodiments of the present invention, a heat dissipation structure having excellent heat dissipation performance over the limit of the basic heat dissipation structure may be implemented by using the latent heat of vaporization (moisture absorption and vaporization in the air) of the hygroscopic polymer.

In addition, by adjusting the vaporization rate of the heat dissipation structure, it is possible to increase the heat dissipation holding time and adjust the heat dissipation performance according to the heat dissipation condition and target performance.

In addition, the heat dissipation structure may be combined with a thermoelectric element and used as a power generation device, a cooling device, or a heating device.

For example, the thermoelectric module including the heat dissipation structure may include an optical communication module, a sensor, a medical device, a measuring device, aerospace industry, a refrigerator, a chiller, a ventilation sheet for a vehicle, a cup holder, a washing machine, a dryer, a wine cellar, It can be used for water purifiers, power supply devices for sensors, thermopiles, wearable devices, and the like.

In particular, since the thermoelectric module according to the embodiments of the present invention may have high heat dissipation performance in a convective environment, it may be suitably used for a wearable device attached to a body or clothing by using a convection phenomenon occurring during walking.

Hereinafter, the heat dissipation structure and the performance of the thermoelectric module according to the present invention will be described in more detail through specific embodiments.

Example 1

Partially spraying the glue on the aluminum radiating fins and spraying a hygroscopic polymer (sodium polyacrylate) in powder form to prepare a heat dissipation structure with a hygroscopic polymer attached thereto, and the heat dissipation structure, a thermoelectric module including a thermoelectric element array and Combined. 6 is a digital photograph of the thermoelectric module of Example 1.

Example 2

The glue is partially sprayed on the copper foam produced by selective etching, and a hygroscopic polymer (sodium polyacrylate) in powder form is sprayed to prepare a heat dissipation structure with a hygroscopic polymer attached thereto, and the heat dissipation structure is thermoelectric. It was combined with a thermoelectric module including an element array. 7 is a digital photograph of the thermoelectric module of Example 2.

In a state where the temperature of the lower substrate of the thermoelectric module (Al Heat sink + SAP, Cu foam + SAP) of Examples 1 and 2 was maintained at 27°C to 40°C, in a 1.5 m/s convection environment of 23°C, the lower part The temperature difference between the substrate and the upper substrate was measured and shown in the graphs of FIGS. 8A and 8B.

In addition, in an environment where the temperature difference is 4°C, the magnitudes of power and voltage output from the thermoelectric modules of Examples 1 and 2 are measured and shown in graphs of FIGS. 9A and 9B.

As a comparative example, the same experiment was performed for a thermoelectric module (Comparative Example 1, Al Heat sink) combined with an aluminum heat sink without a hygroscopic polymer and a thermoelectric module (Comparative Example 2, Cu foam) combined with a copper porous body without a hygroscopic polymer.

Referring to FIGS. 8A and 8B, it can be seen that the thermoelectric module according to the embodiment of the present invention can increase the temperature difference between both ends of the thermoelectric module compared to the thermoelectric module of the comparative example not using a hygroscopic polymer. Accordingly, it can be expected that the thermoelectric module according to the embodiment of the present invention can improve power generation efficiency.

Referring to FIGS. 9A and 9B, the effect of increasing the output voltage and output power of the thermoelectric module according to an embodiment of the present invention can be confirmed. In particular, in the case of a copper porous body, it can be seen that the effect of increasing performance is greater.

10 is a graph showing a temperature difference of a thermoelectric module according to an embodiment of the present invention measured according to a pore size of a copper porous body.

Referring to FIG. 10, it can be seen that the thermoelectric module according to an embodiment of the present invention can exhibit high heat dissipation characteristics in various pore sizes, and through this, it can be expected that it can be applied to heat dissipation structures of various structures and sizes.

11 is a graph showing the cooling performance of a thermoelectric module (metal heat sink + polymer absorbent resin) and a conventional metal heat sink according to an embodiment of the present invention according to humidity.

Typical metal heat sinks have an effect of cooling by transferring heat to the air layer around the metal fins. In the heat dissipation structure of the present invention, since the polymer absorbs moisture in the air and additionally utilizes the heat of vaporization of moisture, the heat dissipation performance can be greatly increased in an environment with high humidity.

Although the above has been described with reference to embodiments, it is understood that those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention described in the following claims. You can understand.

The present invention can be used to manufacture a thermoelectric module for small-scale power generation, cooling and temperature control of various devices, and the like.

Claims (9)

Heat dissipation body; And
A heat radiation structure comprising a hygroscopic polymer combined with the heat radiation body. The heat dissipation structure of claim 1, wherein the heat dissipation body comprises a fin array, and the hygroscopic polymer is disposed between adjacent fins. The heat dissipation structure of claim 1, wherein the heat dissipation body has a metal porous structure. According to claim 1, The hygroscopic polymer is sodium polyacrylate (sodium polyacrylate), polyacrylamide copolymer (polyacrylamide copolymer), ethylene maleic anhydride copolymer (ethylene maleic anhydride copolymer), cross-linked carboxyme?K cellulose ( Cross-linked carboxymethylcellulose), polyvinyl alcohol copolymers (polyvinyl alcohol copolymers) and cross-linked polyethylene oxide (cross-linked polyethylene oxide), characterized in that it comprises at least one selected from the group consisting of a heat radiation structure. The heat dissipation structure of claim 1, further comprising a cover member coupled to the heat dissipation body to cover the hygroscopic polymer, and having a ventilation part connecting an inner space and an outer space in which the hygroscopic polymer is disposed. The heat dissipation structure according to claim 5, wherein the cover member includes a fiber assembly. The heat dissipation structure according to claim 1, wherein the hygroscopic polymer has a powder form, a moisture absorption amount is 30 g/g or more, and a diameter of the powder is 150 μm to 850 μm. A first substrate, a second substrate, a thermoelectric material portion disposed between the first substrate and the second substrate, a first electrode disposed between the first substrate and the thermoelectric material portion, and the thermoelectric material portion and the second A thermoelectric element including a second electrode disposed between the substrates; And
A thermoelectric module including a heat dissipation structure of any one of claims 1 to claim 1 coupled to the first substrate of the thermoelectric element. A wearable device comprising the thermoelectric module of claim 8, wherein the second substrate of the thermoelectric module is attached to a body or clothing.

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