JPS5975684A - Thermo-electric generating element - Google Patents

Abstract

PURPOSE:To enable a high performance thermo-electric generating element to be constructed by a method wherein heat-pipe or the like is employed to cool the lower-temperature end of the main body of the titled element. CONSTITUTION:A P type semiconductor 10A and N type semiconductor 10B are combined constructing the main body of a thermo-electric generating element 10 with a P- N junction 10C located at the higher temperature junction side. A multiplicity of the main bodies 10 are electrically, serially combined. The end of a lower temperature side is thermally connected to a heat-pipe 20 with the intermediary of a layer of heat-resisting, insulating, adhesive agent. Enclosed in the heat-pipe 20 made of metal is a liquid to vaporize at a certain temperature. Thermal radiation is effected due to heat of evaporation. When heat is applied to the PN junction 10C on the higher temperature junction side, due to the difference in temperatures between the higher temperature junction and lower temperature junction, electricity is thermally generated in the multiplicity of main bodies 10, and the total power is lead out. The heat-pipe 20 is capable of keeping the temperature drop to virtual zero when transporting heat in the vicinity of 50W. This means that it is possible to lower the temperature at the lower-temperature side of the main body 10 as low as the temperature of the cooling side, provided with a radiating fin 21 of the heat-pipe 20, thereby thermally generating an adequate quantity of electric power.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermoelectric generating element whose low temperature side end is cooled by a heat pipe.

A thermoelectric power generation element is a thermoelectric direct conversion element that generates electricity using the Seebeck effect (thermoelectric effect) of a substance due to the temperature difference between a high temperature junction and a low temperature junction. In this case, if the semiconductor of iron silicide chopsticks is used for that period of time, a large thermoelectric conversion voltage coefficient (Seebeck coefficient 2 units μV/K) can be obtained, and its moderate electrical conductivity and thermal conductivity result in an extraordinary thermoelectric conversion. It is known that electricity can be consumed.

Generally, the shape of such a thermoelectric generating element is as shown in Fig. 1, with a P-type semiconductor 1 and an N-type semiconductor 2 as legs, one end of which is connected by a conductor 3, and the other end is a lead. 4 as an output terminal. In general, the connected end of both legs is called high-temperature bonding, and the open end is called low-temperature bonding.

In the configuration shown in FIG. 1, the voltage generated between the leads 4, that is, between both output terminals, is determined by the temperature difference (ΔT = Tbi − The value obtained by multiplying Tc) by the Seebeck coefficient α1) which is a constant of ir4 is expressed as the following equation.

Vl)=Qp・ΔT... (1) Similarly, when studying the Seebe-Nck coefficient for N-type semiconductor 2, the following relationship holds true.

v, = Tsutomu・HachiT...(2) P-type semiconductor 1 and N-type semiconductor 2 are connected by conductor 3, so the output voltage is the same as if two batteries were connected in series. V
. =Vp+VH. The power is 2 of Haboko's output voltage.
Since it is proportional to the power of the output voltage V. It turns out that it is extremely important to maximize the temperature, and this can be achieved by increasing the temperature T. In other words, it can be said that a thermoelectric generating element extracts electrical energy according to a thermoelectric conversion coefficient from an energy flow as a heat flow.

Note that in the first M, the P-type semiconductor 1 and the N-type semiconductor 2 are connected to a conductor 3.
Although a configuration in which the conductor 3 is connected is shown, it is also possible to omit the conductor 3 and adopt a structure in which the P-type semiconductor 1 and the N-type 21' guide tree 2 are directly connected.

Considering the characteristics of the thermoelectric generating element described in - above, in order to make the thermoelectric generating element work at maximum efficiency, it becomes a matter of how effectively heat flow can be generated within the thermoelectric generating element. In order to maximize the heat flow Q within the element, it is effective to maximize Δi'(=i', ~T2) from the following equation (3). However, K is the thermal conductivity of the element as shown in Figure 2, S is the cross-sectional area, l is the length,
T , , i” 2 is the temperature at both ends, ΔT +, t T
, and T2. How high the temperature 1' b i of the high-temperature side end, which is a high-temperature bond, is determined depends on (1) the temperature of the heat source, (2) the heat resistance of the thermoelectric material, and (3) the heat collection effect of the thermoelectric material. On the other hand, the temperature T of the low-temperature side end where low-temperature bonding occurs
How to replace c is determined by 1) increasing the amount of heat transport from the low-temperature side end to the surface of the radiator normally provided at the low-temperature side end; and 2)
Heat dissipation is to maximize heat conduction from the book surface to the air or water. 2 is determined by the design of the heat radiator because it is a heat conduction cooling of the heat radiator, and is determined by its effective area and effective heat f large conductivity. What is important is the maximum amount of heat (heat transport) from the low-temperature side end of 1 to the surface of the heat dissipation book. Regarding this point, conventional heat dissipation bodies with heat dissipation fins made of metal such as aluminum It was common to have a structure using

FIG. 3 shows an example of a conventional thermoelectric generator. In this case, the thermoelectric power generation element body 10 has its low-temperature side end fixed onto a heat sink 11 having extruded aluminum fins, which is generally used for heat dissipation in transistors, etc., via a heat-resistant insulating adhesive. . Here, an iron silicide sintered body composed of a P-type semiconductor and an N-type semiconductor is used as the thermoelectric power generation element body 10, and the high-temperature bonding temperature Tbi is heated to 730° C., and the low-temperature bonding temperature In order to cool Tc to 50° C., it is necessary to dissipate approximately 5 W of heat from the low-temperature side end, which is the low-temperature bonding side. Under these conditions, the thermoelectric generator main body 10 generates approximately 50 mW of power, so if 10 mW of power is generated,
When considering a unit of thermoelectric power generation elements with elements connected in series and an output voltage of 3.5 mm and a maximum extractable power of 500 mW, a total of 50 W of heat must be dissipated. At this time, the effective volume of the heat sink 11 in FIG. 3 is (height D) x (width W
) x (length L) = 6 (1+n+nX 1. i l
)++uoX 50u+m, thermal resistance is 2.38
°C/W, and 5 (in the case of IW heat dissipation, the temperature of the thermoelectric power generating element is about 120'C on the surface).

It can be seen that the structure using the conventional metal heat sink as shown in FIG. 3 has the following drawbacks.

(]) The temperature of the low temperature side end of the thermothermal power generation element is the temperature of the heat sink!
, iI4, and the amount of heat transport is small. Therefore, the low temperature end portion is not easily cooled.

(2) Since heat transport is poor, the heat radiator inevitably has a large area. As a result, the overall size becomes larger and the cost becomes higher.
Furthermore, the middle of the heat radiator becomes more likely to be heated by heat radiation.

(3) Since the shape of the heat dissipation book is unusual, it becomes a constraint on device design.

In view of the above points, the present invention uses a heat pipe to cool the low-temperature side end of the thermoelectric power generation element body, thereby effectively lowering the temperature of the low-temperature side end, and achieving a small size and high performance with large thermoelectromotive force. The present invention aims to provide a thermoelectric power generating element.

Embodiments of the thermoelectric generating element according to the present invention will be described below with reference to the drawings.

FIG. 4 shows a first embodiment of the thermoelectric generating element of the present invention. In this figure, the heat pipe 20 is a one-side cooling type 1), and a large number of heat radiation fins 21 are provided on the outer periphery of one end. In addition, at the opposite end, there is a thermoelectric generator main tree 1.
07!1tJ A plurality of heat pipes are fixed to the outer periphery of the heat pipe 20 with a heat insulating adhesive.

Here, the thermoelectric power generating element main body 10 is, for example, a P-type semiconductor 1. The OA and the N-type semiconductor 10B are bonded, and the F'N junction 10C is on the high temperature bonding side.
A lead wire (not shown) made of copper or the like is connected to the open end, which is the low-temperature bonding side, and each thermoelectric power generation element body 10 is electrically connected in series. Further, the low-temperature side end portion of each thermoelectric generating element main body 10 that is to be joined at a low temperature is thermally coupled to the heat pipe 20 via a layer of heat-resistant insulating adhesive. heat pipe 20
A liquid that vaporizes at a predetermined temperature is sealed in a sealed metal pipe, and heat is radiated (heat transported) by the action of the heat of vaporization of the liquid inside.

In the configuration of the first embodiment, 1-) on the high-temperature bonding side.
When the N-junction 10C is heated by the heat source of a gas burner chopstick, a thermoelectromotive force is generated in each element body 10 due to the temperature difference between the high temperature junction temperature T I + i and the low temperature junction temperature '1゛c, and the sum of these is the external It is taken out. At this time, the heat pipe 20 can make the temperature drop substantially zero in heat transport of about 50 W, and the low temperature side end of the element body 10 is substantially connected to the radiation fins 21 of the heat pipe 20.
It becomes possible to cool down to the temperature of the cooling side provided with.

Therefore, sufficient thermoelectromotive force can be obtained.

According to the first embodiment, the following effects can be achieved.

(1) Since the heat pipe 20 is used, heat transport is effective and the temperature at the low temperature side end of the thermoelectric generating element 10 can be easily lowered. Therefore, thermoelectromotive force can be increased.

(2) By using the heat pipe 20, the heat transport path can be localized in a pipe shape. Therefore, it is possible to reduce the size and is advantageous in terms of workability and ease of removal.

(3) The shape of the heat pipe is not only linear, but also has flexibility in bending and bending, which is advantageous in terms of design and makes it easy to channelize heat.

Figure ff15 shows a second embodiment of the present invention. In this case, the heat pipe 30 is of a both-end cooling type, and the heat radiation fins 21 are provided at both ends, and the thermoelectric power generation element main body 10 is provided in the middle part. In this case, the effect is substantially the same as that shown in FIG. 4 except that both ends of the heat pipe 3 +, ) are cooled.6 FIG. 6 shows an application example using the thermoelectric generating element of the invention, This shows a case where a thermoelectric generator is attached to a kerosene stove. In this figure, a hemispherical reflecting plate 41 is provided on the front side of a main body frame 40 of the oil stove, and a lamp wick 42 is disposed in the center of the reflecting plate 41. Also, the reflective plate 41
An oil tank 43 is arranged behind. Thermoelectric power generation element 5
0 has radiation fins 2 at both ends of the M-shaped heat pipe 30A.
1, and a plurality of thermoelectric power generating element bodies 10 are arranged in the middle part of the M-shaped heat pipe 30A. and,
The high-temperature end portion of each thermoelectric power generating element main body 1o, which is a high-temperature joint, is heated by the flame generated in the lamp wick portion 42. Further, a blower fan 44 is arranged to cool the radiation fins 21 of the heat pipe 3 ( ), and this blower fan 44 is operated by the thermoelectromotive force of the thermoelectric generator 50 .

In the configuration of the kerosene stove shown in FIG.
The blower fan 44 is actuated by the thermoelectromotive force in parentheses, cooling each radiation fin 21 as shown by arrow X, and sending the warmed air forward of the main body frame 4o, and the blower fan 44 cools the heat pipe 30A. It can perform both the functions of blowing out hot air and blowing out hot air.

FIG. 7 shows an example of the application of the pond of the present invention, in which a bath pot is constructed. In this case, the thermoelectric generating element 60 is
A fourth heat generating element is provided with heat dissipation fins 21 on the heat pipe 20, and a plurality of thermoelectric power generation element bodies 10 are provided on the end of the heat pipe 2o.
As shown in the figure, the side of the heat pipe 2o provided with the radiation fins 21 protrudes into the bathtub 61, and the other end, the high temperature side end of the thermoelectric power generation element body 10, is heated by the burner 62. It looks like this.

In the bathtub shown in FIG. 7, the heat from the burner 62 is transported to the liquid in the bathtub 61 through the high-temperature end, the low-temperature end, the heat pipe 20, and the radiation fins 21 of the thermoelectric generating element main body 1o. The inside of the bathtub 61 will be heated. In addition, since one end of the heat pipe 2o is always inside the bathtub 61, it is maintained at the temperature of the hot water in the bathtub (around 4()°C), and as a result, the low-temperature side end of each thermoelectric generating element 10 is The temperature will be kept at around °C. As a result, by making the overall thermoelectromotive force of the thermoelectric generating element 60 sufficiently large, this thermoelectromotive force can be used to operate the stirring device 63 or to detect the temperature of hot water in the bathtub. Activate the detector 64,
The process ends by activating a timer 65 that defines the heating time of the burner 62.

In addition to the application example described in 1., various other applications are possible for gas and petroleum solid fuel combustion appliances.

As explained above, according to the present invention, by cooling the low-temperature side end of the thermoelectric power generation element body using a heat pipe, it is possible to obtain sufficient thermoelectromotive force with a small size, and it is possible to achieve high performance thermoelectric power generation. It is possible to construct an element, and its practical effects are extremely large.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an example of the structure of a thermoelectric power generating element, Fig. 2 is an explanatory diagram for explaining heat transport of the element, Fig. 3 is a perspective view showing a conventional thermoelectric generating element, and Fig. 4 is a front view showing an example of the structure of a thermoelectric generating element. The figure is a front view showing the first embodiment of the thermoelectric generating element according to the present invention, FIG. 5 is a front view showing the second embodiment of the present invention, and FIG. FIG. 7 is a schematic plan view of the constructed bathtub, and FIG. 7 is a schematic side view of the bathtub, which is another application example of the present invention. 1()...thermal power generation element body, 2.1), 30,
30 A... Heat pipe, 21... Radiation fin. Special II applicant Tokyo Denki Kagaku Kogyo Co., Ltd. Representative Patent attorney Takashi Murai Figure 5

Claims (2)

[Claims] (1) A thermoelectric power generation element characterized in that the low temperature side end of the thermoelectric power generation element main body is thermally coupled to a heat pipe. (2) The thermoelectric power generating element according to claim 1, wherein the heat pipe has cooling fins on its outer periphery.