KR102383398B1 - Energy harvesting device - Google Patents

Abstract

Energy harvesting device according to an embodiment of the present invention is a heat diffusion comprising a first region in contact with a region having a first thermal resistance and a second region in contact with a region having a second thermal resistance higher than the first thermal resistance a plate, a plurality of thermoelectric modules disposed on the heat spreader plate, a heat insulating material disposed between the plurality of thermoelectric modules, and a heat sink disposed on the thermoelectric modules, wherein the first one of the plurality of thermoelectric modules The number of thermoelectric modules disposed on the region is greater than the number of thermoelectric modules disposed on the second region.

Description

Energy Harvesting Device {ENERGY HARVESTING DEVICE}

The present invention relates to an energy harvesting device, and more particularly, to an energy harvesting device using human body heat.

There are various devices for harvesting energy. One of them is a thermoelectric element. A thermoelectric element is a device used to convert thermal energy into electrical energy or electrical energy into thermal energy. Specifically, the thermoelectric element can convert thermal energy into electrical energy using the Seebeck effect, in which an electromotive force is generated by the temperature difference between both ends, and a temperature difference occurs at both ends of the thermoelectric element by applying an external current. It can be used as a cooling element by using the Peltier effect.

Specifically, when a predetermined temperature difference (ΔT) is given at both ends of the thermoelectric module, a voltage (V) is generated in proportion thereto. In the thermoelectric module, the N legs may be connected in series, and in this case, the voltage Vo may be Vo=N*SΔT. S is the Seebeck coefficient. In order to use the electromotive force generated in this way, when the thermoelectric module is connected to the power consumption device, Po = _{R L} * ₍ N* SΔT) ² /(R _M +R _L ) ² of electrical energy (Po) is transferred. Therefore, the maximum power P _MAX when R _M =R _L = (N*SΔT) ² /4R _M ² is produced.

Among energy harvesting devices, in the case of an energy harvesting device that harvests energy by using human heat, there are difficulties in designing due to non-uniformity of skin thermal resistance for each part, variation for each subject, and fluctuations in daily life. The human body maintains temperature homeostasis through blood circulation, and the skin plays a role in preventing excessive cooling of blood and at the same time dissipating appropriate heat, so that the internal temperature of the human body is maintained at around 36 degrees. Since the normal room temperature is 25 degrees, there is a difference of about 10 degrees from the human body temperature. However, since the skin has thermal resistance, a certain temperature difference also occurs in the skin, so the actual temperature difference applied to the thermoelectric module is less than 10 degrees. Analyzing this with a formula is as follows.

, 열전 모듈의 열저항을

이라하고 인체 내부의 온도를 T_B, 외기온도를 T_A라 할 때 인체에서 외기로 흘러나가는 열량(Q)은

이므로 열전 모듈에는

의 온도차이가 인가된다. 따라서 열전 소자를 통해 획득할 수 있는 최대 전력은

일 수 있다. heat resistance of the skin

, the thermal resistance of the thermoelectric module

Assuming that the internal temperature of the human body is T _B and the external air temperature is T _A , the amount of heat (Q) flowing from the human body to the outside air is

Therefore, the thermoelectric module

temperature difference is applied. Therefore, the maximum power that can be obtained through the thermoelectric element is

can be

이고, 열전소재의 고유물성인

로 나타내면, 최대 전력은

이므로

일 때 발전량이 최대가 된다.If N is the number of thermoelectric legs with cross-sectional area A and height d per module, then

and the intrinsic property of the thermoelectric material

Expressed as , the maximum power is

Because of

When the power generation is at its maximum.

이고, 발전 효율을

라할 때

이므로

이 된다. 즉, 상기 설명한 바와 같은 최적화를 위해서는

인 모듈을 설계하는 것이 중요하다. 그런데

의 값이 남녀노소 및 유전적 차이에 따라 다르며 동일한 사람의 경우에도

값이 시시각각 변화하기 때문에 적정한 목표치를 정하기 어려워 모듈을 설계하는데 어려움이 있다.At this time, the power

and the power generation efficiency

when you say

Because of

becomes this That is, for the optimization as described above,

It is important to design modules that are By the way

The value of is different for all ages and genetic differences, and even in the same person

Since the value changes every moment, it is difficult to set an appropriate target value, making it difficult to design a module.

An object of the present invention relates to an energy harvesting device attached to a human body, and an object of the present invention is to provide an energy harvesting device with improved energy harvesting efficiency.

Energy harvesting device according to an embodiment of the present invention is a heat diffusion comprising a first region in contact with a region having a first thermal resistance and a second region in contact with a region having a second thermal resistance higher than the first thermal resistance a plate, a plurality of thermoelectric modules disposed on the heat spreader plate, a heat insulating material disposed between the plurality of thermoelectric modules, and a heat sink disposed on the thermoelectric modules, wherein the first one of the plurality of thermoelectric modules The number of thermoelectric modules disposed on the region is greater than the number of thermoelectric modules disposed on the second region.

According to an embodiment of the present invention, the arrangement interval or the number of arrangement per area of the thermoelectric module included in the energy harvesting device may be differently arranged according to thermal resistance. Therefore, it is possible to minimize the increase in investment cost and manufacturing cost caused by designing and manufacturing modules of various thermal resistances using thermoelectric modules having the same thermal resistance.

1A and 1B are perspective views illustrating a state of use of an energy harvesting device according to an embodiment of the present invention.
FIG. 2A is a schematic cross-sectional view taken along II′ of the energy harvesting device of FIG. 1A .
Figure 2b is a schematic cross-sectional view taken along II-II' of the energy harvesting device of Figure 1b.
3A is a schematic cross-sectional view of an energy harvesting device according to another embodiment of the present invention corresponding to a portion taken along II′ of the energy harvesting device of FIG. 1A .
3B is a schematic cross-sectional view of an energy harvesting device according to another embodiment of the present invention corresponding to a portion taken along II - II′ of the energy harvesting device of FIG. 1B .

Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In this specification, when a component (or region, layer, part, etc.) is referred to as being “on”, “connected to” or “coupled to” another component, it is directly connected/connected on the other component. It means that they may be coupled or that a third component may be disposed between them.

Like reference numerals refer to like elements. In addition, in the drawings, thicknesses, ratios, and dimensions of components are exaggerated for effective description of technical content. “and/or” includes any combination of one or more that the associated configurations may define.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In addition, terms such as "below", "below", "above", and "upper side" are used to describe the relationship of the components shown in the drawings. The above terms are relative concepts, and are described based on directions indicated in the drawings.

Terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification is present, and includes one or more other features, number, or step. , it should be understood that it does not preclude the possibility of the existence or addition of an operation, a component, a part, or a combination thereof.

1A and 1B are perspective views illustrating a state of use of an energy harvesting device according to an embodiment of the present invention.

1A and 1B , the energy harvesting device 100 may be attached to a human body. The energy harvesting apparatus 100 may convert thermal energy generated by the human body into electrical energy. The energy harvesting device 100 may specifically include a thermoelectric module. The thermoelectric module may include various materials.

The performance of the thermoelectric material used in the thermoelectric module depends on the figure of merit expressed as ZT, and its value is expressed by Equation 1 below.

[Equation 1]

는 전기 전도도,

는 열전도도, Z는 열전 재료의 고유 물성값, T는 절대 온도이다. 일반적으로 열전 재료는 상온에서 ZT 값이 약 1인 Bi2Te3계 물질일 수 있다. 이 외에도 동작 온도에 따라, ZT값이 1 내외의 값을 갖는 PbTe, SiGe, Zn4Sb3, Yb14MnSb11, Mg2Si 계 물질들이 사용될 수 도 있다. 다만, 이는 예시적인 것으로, 에너지 수확 장치(100)가 포함하는 열전 재료가 상기 예시한 물질에 한정되는 것은 아니다. where S is the Seebeck coefficient,

is the electrical conductivity,

is the thermal conductivity, Z is the intrinsic property value of the thermoelectric material, and T is the absolute temperature. In general, the thermoelectric material may be a Bi2Te3-based material having a ZT value of about 1 at room temperature. In addition, PbTe, SiGe, Zn4Sb3, Yb14MnSb11, or Mg2Si-based materials having a ZT value of about 1 may be used depending on the operating temperature. However, this is an example, and the thermoelectric material included in the energy harvesting device 100 is not limited to the above-described material.

1A and 1B, the energy harvesting device 100 is exemplarily shown in a form worn on the wrist. In this case, the energy harvesting apparatus 100 may be a smart watch combined with a display and the like to display time information, message information, and the like. In addition, the energy harvesting device 100 may be an electronic device attached to the skin to detect a biosignal.

1A exemplarily illustrates the inner wrist 200a having relatively low skin thermal resistance, and FIG. 1B exemplarily illustrates the outer wrist 200b having relatively high skin thermal resistance. Specifically, the inner wrist 200a may be a portion of the wrist seen when the palm is viewed, and the outer wrist 200b may be a portion of the wrist visible when the back of the hand is viewed.

The outer wrist 200b is farther from the main blood vessels than the inner wrist 200a, and the skeleton is also located between the main blood vessels and the outer wrist 200b, so it has a higher thermal resistance than the inner wrist 200b. . According to an embodiment of the present invention, the arrangement interval or the number of arrangement per area of the thermoelectric module included in the energy harvesting apparatus 100 may be differently arranged according to thermal resistance. Therefore, it is possible to minimize the increase in investment cost and manufacturing cost caused by designing and manufacturing modules of various thermal resistances using thermoelectric modules having the same thermal resistance.

Figure 2a is a schematic cross-sectional view taken along II' of the energy harvesting device of Figure 1a, Figure 2b is a schematic cross-sectional view taken along II-II' of the energy harvesting device of Figure 1b.

2A and 2B , the energy harvesting apparatus 100 may include a heat spreader 110 , a thermoelectric module 120 , a heat insulator 130 , and a heat sink 140 .

The heat spreader 110 may be attached to the human body. The heat diffusion plate 110 may include a material having excellent thermal conductivity. For example, the heat diffusion plate 110 may include a metallic material.

The heat spreader 110 has a flexible property, so that it can be in close contact with the human body 200 (refer to FIG. 1 ). However, the present invention is not limited thereto, and the heat diffusion plate 110 itself has a curvature and may have a structure in close contact with the human body.

The thermoelectric module 120 may be disposed on the heat spreader 110 . A plurality of thermoelectric modules 120 may be provided, and the arrangement interval of the thermoelectric modules 120 or the number of arrangement per area may be differently arranged according to the thermal resistance of the human body.

)은 열전도도(

)와

의 관계에 있으며 여기서 d는 온도 차가 고려되는 경로의 길이이고, A는 단위 면적이다. 온도 차가 고려되는 경로상에 서로 다른 열전도도

를 갖는 물체로 연결되어 있다면

로 계산된다. 즉, 피부 열 저항은 단순히 피부의 열 물성뿐만 아니라 인체 내부의 온도 최고점으로부터의 경로의 영향도 받는다. 손목 바깥쪽(200b, 도 1b 참조)은 손목 안쪽(200a, 도 1a 참조)에 비해 주요 혈관과의 거리가 멀뿐더러 인체 내부의 온도 최고점으로부터의 경로 상에 골격도 위치하고 있어 결과적으로 손목 안쪽(200a, 도 1a 참조)에 비해 높은 열저항을 갖는다. thermal resistance (

) is the thermal conductivity (

)Wow

where d is the length of the path for which the temperature difference is considered, and A is the unit area. Different thermal conductivities along the path where the temperature difference is considered

If connected by an object with

is calculated as That is, the skin thermal resistance is affected not only by the thermal properties of the skin, but also by the path from the temperature peak inside the human body. The outside of the wrist (200b, see Fig. 1b) is farther from the main blood vessels than the inside of the wrist (200a, see Fig. 1a), and the skeleton is also located on the path from the highest temperature inside the human body, resulting in the inside of the wrist (200a) , see Figure 1a) has a higher thermal resistance.

According to the present invention, more thermoelectric modules 120 may be disposed on the inner side of the wrist 200a (see FIG. 1A ) having low thermal resistance than on the outside of the wrist 200b (see FIG. 1B ). In particular, more thermoelectric modules 120 may be disposed in the central portion through which the artery passes even on the inner side of the wrist 200a (refer to FIG. 1A ).

The thermoelectric modules 120 disposed on the inner side of the wrist 200a (refer to FIG. 1A ) and the outer side of the wrist 200b (refer to FIG. 1B ) may be identically designed thermoelectric modules. Thermal matching can be performed by adjusting the arrangement density of the thermoelectric modules 120 all equally designed to have a thermal resistance smaller than the thermal resistance of the skin on the thermal diffusion plate 110 .

이라고 한다. 이 경우, 열 확산판(110)과 인체와의 평균 열저항은

로 나타낼 수 있다. 따라서

이 되도록 모듈 하나당 확산판 면적이 A가 되도록 설계하면 고정된 모듈 열저항(

)의 모듈을 가지고도 다양한 부위에 적용할 수 있다. 따라서, 본 발명에 따르면 열전 모듈의 열저항을 피부 각 부위의 열저항에 맞추어 개별적으로 설계할 필요가 없을 뿐 아니라 온도나 습도와 같은 환경의 변화나 식사, 운동, 작업, 취침과 같은 일상 생활에 의한 신체적인 변화로 인한 피부 열저항의 변화에도 영향을 덜 받게 되어 높은 효율로 에너지를 수확할 수 있다. Assuming that the temperature on the heat spreader plate 110 is the same, the thermal resistance of each position of the skin in contact with the heat spreader plate 110 having an overall area of A

It is said In this case, the average thermal resistance between the heat spreader 110 and the human body is

can be expressed as thus

If the diffuser plate area per module is designed to be A, the fixed module thermal resistance (

) can be applied to various areas even with the module. Therefore, according to the present invention, it is not necessary to individually design the thermal resistance of the thermoelectric module according to the thermal resistance of each part of the skin, and it is not only necessary to change the environment such as temperature or humidity, or to change the environment such as meal, exercise, work, and sleep. Energy can be harvested with high efficiency as it is less affected by changes in skin thermal resistance caused by physical changes.

The insulator 130 may be disposed in a space between the thermoelectric modules 120 . By disposing the heat insulating material 130 in the space between which the thermoelectric module 120 is not disposed, it is possible to minimize heat dissipation to the outside through the space in which the thermoelectric module 120 is not disposed.

The heat sink 140 may be coupled to the thermoelectric module 120 to facilitate heat dissipation of the side from which heat is emitted. A planar area of the heat sink 140 may be larger than a planar area of the thermoelectric module 120 .

Figure 3a is a schematic cross-sectional view of the energy harvesting device according to another embodiment of the present invention corresponding to a section taken along I-I' of the energy harvesting device of Figure 1a, Figure 3b is II - II of the energy harvesting device of Figure 1b It is a schematic cross-sectional view of an energy harvesting device according to another embodiment of the present invention corresponding to a section cut along '.

3A and 3B , the energy harvesting device 100a may further include an electronic circuit EC and a display DD when compared to the energy harvesting device 100 previously described in FIGS. 2A and 2B . can

The electronic circuit EC may be a circuit for controlling the driving of the display DD. The electronic circuit EC may generate heat when operating. Heat generated in the electronic circuit EC may be transferred to the thermoelectric module 120 through the heat spreader 110 . That is, in addition to the body temperature, a heat source may be additionally provided.

Since the thermal resistance is high, the display DD may be disposed in a portion where the thermoelectric module 120 is small. That is, in order to secure an area in which the display DD is disposed, a space between the thermoelectric modules 120 may be used without a large loss of energy.

Although the above has been described with reference to the preferred embodiment of the present invention, those skilled in the art or those having ordinary knowledge in the technical field will not depart from the spirit and technical scope of the present invention described in the claims to be described later. It will be understood that various modifications and variations of the present invention can be made without departing from the scope of the present invention. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: energy harvesting device 110: heat spreader plate
120: thermoelectric module 130: insulation material
140: heat sink

Claims (10)

a heat spreader comprising a first region in contact with a region having a first thermal resistance and a second region in contact with a region having a second thermal resistance higher than the first thermal resistance;
a plurality of thermoelectric modules disposed on the heat spreader;
an insulator disposed between the plurality of thermoelectric modules;
a heat sink disposed on the thermoelectric modules;
a display disposed on the second area of the heat spreader; and
an electronic circuit disposed on the first region of the heat spreader for controlling driving of the display;
Among the plurality of thermoelectric modules, the number of thermoelectric modules disposed on the first region is greater than the number of thermoelectric modules disposed on the second region;
An energy harvesting device in which heat generated in the electronic circuit is transferred to the thermoelectric module through the heat spreader.
According to claim 1,
An energy harvesting device in which an area on a plane of the heat sink is greater than an area on a plane of the thermoelectric module.
According to claim 1,
The thermoelectric module comprises at least one of Bi ₂ Te ₃ , PbTe, SiGe, Zn ₄ Sb ₃ , Yb ₁₄ MnSb ₁₁ , and Mg ₂ Si.
According to claim 1,
The heat diffusion plate is an energy harvesting device having a flexible property or a structure having a curvature.
According to claim 1,
The heat diffusion plate is an energy harvesting device comprising a metallic material.
According to claim 1,
The heat insulator and the heat sink are energy harvesting device spaced apart from each other.
According to claim 1,
The display is an energy harvesting device disposed between the thermoelectric modules.
According to claim 1,
The heat insulator is an energy harvesting device exposing an upper portion of each of the thermoelectric modules.
According to claim 1,
The heat spreader is an energy harvesting device that is attached to the human body.
According to claim 1,
The energy harvesting device is an energy harvesting device that is a smart watch or an electronic device that detects a biosignal.

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