JPH0448150Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a heat source for direct power generation by effectively utilizing industrial waste heat (heat retained in exhaust gas from industrial furnaces, incinerators, engines, etc., exhaust steam, exhaust temperature). This relates to a thermoelectric power generation device that recovers and uses the energy as electricity.

[Prior Art] In the device shown in Fig. 6, P-type and N-type semiconductors 1 and 2 are alternately connected by metal pieces 3 and 4, and are arranged electrically in series and in parallel with a heat source. This is a thermoelectric element assembly 5. A conventional thermoelectric power generation device that uses this thermoelectric element assembly 5 and aims to be small and compact is as shown in FIG.
It is stacked in a sandwiched manner, and is mainly applied to low-temperature differences and small-capacity products that are less affected by thermal deformation and thermal stress.

In this case, the contact surfaces between the thermoelectric element assembly 5 and the high- and low-temperature side ducts 7 and 6 are bonded with an adhesive (electrical insulation, good thermal conductivity), or are considered to be in close contact with each other via grease or the like. ing. The tightening spring 8 is for pressing to improve the contact between the thermoelectric element assembly 5 and the high/low temperature side ducts 7, 6, and is used when no adhesive is used or when there is a risk of the adhesive part peeling off. is required.

[Problem that the invention attempts to solve]

However, in the above configuration, during operation, the high and low temperature side ducts 7 and 6 themselves, the thermoelectric element assembly 5 itself, and the mutual relationship between the high and low temperature side ducts 7 and 6 and the thermoelectric element assembly 5 in the stacking direction and the direction perpendicular to the stacking. In addition, since the high and low temperature side ducts 7 and 6 and the thermoelectric element assembly 5 are made of different materials, a difference in free thermal expansion occurs, but this thermal expansion cannot be absorbed much due to the structure.

Therefore, during use, cracks may occur in various parts due to deformation or thermal fatigue, and gaps may occur between the thermoelectric element assembly 5 and the high/low temperature side ducts 7, 6, resulting in a decrease in heat transfer performance and the like. Instability has also led to a decline in power generation capacity and instability.

The present invention was developed in view of the above circumstances, and maintains small size and compactness while preventing the generation of thermal stress and damage to thermoelectric elements, as well as preventing increases and fluctuations in heat transfer resistance and improving power generation efficiency. The object of the present invention is to provide a thermoelectric power generation device capable of improving the power generation voltage and stabilizing the generated voltage.

[Means and effects for solving the problem] The present invention incorporates passage ducts 14 and 46 through which the internal fluid B flows inside the external fluid ducts 10 and 10' through which the external fluid A flows. Duct 1
A thermoelectric element assembly 5 having an electric terminal 28 for taking out the generated power is fixed to the outer surfaces of the thermoelectric elements 4 and 46 so that the inner surfaces thereof are closely joined, and the outer surfaces are exposed to the external fluid. The temperature difference between the external fluid A and the internal fluid B acts on the thermoelectric element assembly 5, and the electromotive force generated at this time is used to generate electricity. At this time, the external fluid A is brought into direct contact with one side of the thermoelectric element assembly 5.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5.

In FIGS. 1 and 2, 10 is an external fluid duct, and 11 is an internal fluid duct installed in the external fluid duct 10 in a direction perpendicular to the fluid flow direction of the external fluid duct 10. It's a duct.

The external fluid duct 10 is composed of an inner wall member 12, a side wall member 17 that supports both ends of the internal fluid duct 11, and a heat insulating material 13 that covers the outer surfaces of these wall members 12 and 17.

Further, the internal fluid duct 11 has a fitting hole 1 provided on both side walls 17, 17 of the external fluid duct 10.
Holding portions 16, 16 on both sides fitted and supported by 8
and a passage duct 14 formed in a flat tubular shape and arranged parallel to the fluid flow direction of the external fluid duct 10, and a large number of fins 15 are provided within this passage duct 14. Reference numeral 19 denotes an O-ring for maintaining airtightness between the holding portions 16, 16 and the fitting hole portion 18. Note that this part may have an airtight welded structure.

Passage duct 14 of the internal fluid duct 11
The thermoelectric element assembly 5 is attached to the outer surface of the thermoelectric element assembly 5 via an adhesive layer 25.
is glued. This thermoelectric element assembly 5 has the same structure as the conventional one, in which P-type semiconductor 1 and N-type semiconductor 2, which are thermoelectric elements, are connected alternately with metal pieces 3 and 4, and one of the metal pieces As described above, the passage duct 1 is connected to the third side through the adhesive layer 25.
It is glued to the outer surface of 4.

The thermoelectric element assembly 5 is surrounded by a heat insulating mold 26, and between the elements is an inter-element mold 2.
7, and one metal piece 4 is exposed to the external fluid duct 10 side. Reference numeral 28 denotes an electric terminal for taking out the electromotive force between the two metal pieces 3 and 4 of the thermoelectric element 5.

Each of the molds 26 and 27 is made of a heat insulating resin, which insulates areas other than the thermoelectric element and between the thermoelectric elements to efficiently transfer heat within the thermoelectric element. It may depend on

In the above configuration, when, for example, high-temperature fluid A is flowed into the external fluid duct 10 and low-temperature fluid B is flowed into the passage duct 14 of the internal fluid duct 11, each thermoelectric element of the thermoelectric element assembly 5 at this time An electromotive force is generated due to the temperature difference acting on the electrodes, and electric power is obtained by extracting this electromotive force from the electric terminal 28.

At this time, one metal piece 4 connecting the thermoelectric elements 1 and 2 of the thermoelectric element assembly 5 is exposed in the external fluid duct 10, so that the fluid flowing in the external fluid duct 10 is Heat is efficiently applied to each thermoelectric element.

In addition, each thermoelectric element 1, 2 of the thermoelectric element assembly 5
One metal piece 3 of both metal pieces 3 and 4 connecting
is fixed to the passage duct 14 of the internal fluid duct 11, but since the other metal piece 4 is in a free state, each thermoelectric element including the thermoelectric element is small. The structural parts can be almost freely deformed. Therefore, almost no thermal stress is generated, and the bond between the thermoelectric element assembly 5 and the passage duct 14 of the internal fluid duct 11 is maintained stably without peeling, thereby improving power generation efficiency and stabilizing the output. Further, in this case, the surface of the passage duct 14 of the internal fluid duct 11 is almost covered with the thermoelectric element assembly 5, so that the thermoelectric power generation device can be kept small and compact.

What is shown in FIG. 3 is another embodiment of the present invention, in which internal and external fluid ducts 11 and 10 are arranged concentrically to form a cylindrical passage duct 14 around the outer periphery of the internal fluid duct 11. A cylindrical thermoelectric element assembly 5 is provided.

In the thermoelectric element assembly 5 in each of the above embodiments, if the temperature difference between the internal and external fluids B and A is large, the amount of power generation increases, which is convenient, but if this temperature difference is very large, the thermal expansion difference between the metal pieces 3 and 4 A large thermal stress is generated inside the thermoelectric element and at the adhesive part between the thermoelectric element assembly 5 and the passage duct 14 of the internal fluid duct 11, causing separation of the adhesive part between the thermoelectric element assembly 5 and the passage duct 14. There is a risk that the thermoelectric element assembly 4 may be damaged.

In such a case, as shown in FIG. 4, a bending buffer section 30 for absorbing thermal expansion is provided on the metal piece 4' that comes into contact with the high temperature fluid. That is, metal piece 4'
A bending buffer section 30 is provided in the center between the P and N type semiconductors 1 and 2 in a direction perpendicular to the longitudinal direction of the metal piece.

Therefore, when the temperature difference between the two metal pieces 3 and 4 is very different, the bending buffer 30 absorbs the difference in thermal expansion and prevents the thermoelectric element assembly 5 from being damaged. passage duct 1
It can prevent peeling from 4.

The bending buffer portion 30 also has the efficiency as a fin that increases the heat transfer area of the metal piece 4', and the larger the size, the greater the fin effect.

Further, exhaust gas from industrial furnaces, incinerators, engines, etc. is used as the fluid on the high temperature side, and this exhaust gas generally contains large amounts of sulfuric acid, soot, and dust. When this exhaust gas is used as a high-temperature fluid, sulfuric acid vapor enters through the gap between the thermoelectric element and the mold 27 between the elements, condenses inside and becomes sulfuric acid, which corrodes the expensive thermoelectric element and makes it unusable.In addition, soot and dust are released on the surface of the thermoelectric element. etc., which significantly reduces heat transfer from the external fluid and power generation capacity, and also electrically shorts adjacent thermoelectric elements, greatly reducing the amount of electrical output extracted to the outside. Removal of this soot, dust, etc. must be carried out frequently, but it is very labor-intensive because the thermoelectric element is small and fragile.

In order to solve this problem, as shown in FIG. 5, a water tank 3 is installed below the external fluid duct 10' which houses the internal fluid duct 11 and is sealed.
2 is provided, and an evaporation pipe 33 is passed through this water tank 32.
Exhaust gas may be caused to flow through the evaporation tube 33, and pure water may be evaporated with this heat to operate the steam as the high-temperature fluid A.

That is, the steam condenses on the surface of the metal piece 4 on the surface of the thermoelectric element, radiates heat, becomes water droplets, and falls into the water tank, completing the cycle. Then repeat this cycle.

For this reason, the thermoelectric element assembly 5 is always kept clean from sulfuric acid, soot, and the like.

In addition, the external fluid duct 10' and the water tank 3
2 is provided with a heat insulating layer 34, so almost no heat is radiated to the outside, and since everything except the thermoelectric element assembly 5 is covered with a heat insulating material 26, most of the heat passes through the thermoelectric element assembly 5 and is transferred to the low-temperature fluid. Flows to B. Therefore, the heat of evaporation is effectively utilized by the thermoelectric element assembly 5.

In addition, the heat transfer from the exhaust gas to the thermoelectric element assembly 5 involves both boiling and condensation heat transfer of water, which is the same principle as a heat pipe, and both heat transfers are extremely slow compared to the heat transfer of fluids. Since the heat transfer performance is high, the temperature drop resulting in loss when passing through pure water is so small as to be ignored. Note that other heat media that boil and condense may be used instead of water.For example, if a high boiling point medium such as a mixture of diphenyl oxide and diphenyl oxide is used, a sealed external fluid duct can be used even when used at high temperatures. It is possible to keep the pressure inside 10' low and maintain safety.

Furthermore, when water vapor is used as the external fluid in the conventional thermoelectric generator shown in FIG. 7, the temperature of this water vapor is high, so the high-temperature side passage 7 and the part of the thermoelectric element assembly 5 in contact with it are extremely exposed when the operation is stopped. It will be subject to large temperature changes.

The free thermal expansion of each part accompanying this temperature change can hardly be absorbed by the configuration of a conventional thermoelectric generator. body 5
A gap was generated between the high-temperature side passage 7 and the high-temperature side passage 7 due to thermal deformation, resulting in a decrease in heat transfer performance and instability.

In order to solve this problem, as shown in FIG.
The thermoelectric element assembly 5 is attached to the steam chamber 4.
The configuration is such that it is accommodated within 0.

That is, in FIG. 8, 40 is a steam chamber as a duct for external fluid, and this steam chamber 40 is formed by closing both sides of a body 41 with a cover 42, and the body 41 and cover 42 are covered with a heat insulating material 43. ing. The steam chamber 40 has an inlet 44 for water vapor, which is an external fluid (high temperature), and an outlet 45 for condensed water.
is provided.

In addition, the internal fluid duct 11 is a passage duct 46.
A large number of fins 47 are provided inside the passage duct 46. This passage duct 46
The holding portion 48 is inserted into the insertion hole 4 of the cover 42.
8' via an O-ring seal 49.

The thermoelectric element assembly 5 has adhesive layers 5 on both outer surfaces of the flat tube portion of the passage duct 46 of the internal fluid duct 11.
It is attached by 0.

Also, the passage duct 46 of the internal fluid duct 11
The surface of the thermoelectric element assembly 5 other than the thermoelectric element assembly 5 and between the thermoelectric elements are covered with a heat insulating material 51 such as silicone resin.

Therefore, most of the water vapor flowing from the inlet 44 of the steam chamber 40 is condensed on the metal piece 4 which is the surface electrode of the thermoelectric element assembly 5, and most of the condensed heat passes through the thermoelectric elements 1 and 2 and flows into the cooling water. This will result in more efficient power generation.

Since water vapor is an electrically insulating part and is chemically stable, heat can be transferred through direct contact with the thermoelectric element assembly 5, making the conventional high temperature side passage 7 unnecessary.

For this reason, there is no heat transfer resistance for heat exchange for steam, so the temperature difference in the thermoelectric element assembly 5 increases by that temperature, and the power generation efficiency increases.

Since the high-temperature side passage 7 is unknown, there is no restriction caused by temperature changes in the high-temperature side passage 7 to the thermoelectric element assembly 5, so damage to the thermoelectric element assembly 5 due to thermal stress and heat transfer to the thermoelectric element assembly 5 are prevented. This eliminates defects and enables stable and efficient power generation.

In addition, most of the heat of the water vapor passes through the thermoelectric elements 1 and 2 due to the heat insulating material 51, so that efficient power generation can be performed. They are arranged almost vertically, which allows the condensed water to fall quickly and condense new steam, promoting heat transfer and increasing the efficiency of power generation.

What is shown in FIG. 9 is an embodiment of the above-mentioned steam-water type thermoelectric power generation device, in which an inlet 44 is provided in the upper part of the steam chamber 40 and an outlet 45 is provided in the lower part. Six internal fluid ducts 11 with aggregates 5 attached on both sides are arranged, and an electric terminal 52 for taking out the generated power is provided at the upper part of the steam chamber 40.

[Effect of idea]

Since the present invention is as described above, for example, by flowing a high temperature fluid through the external fluid ducts 10, 10' and flowing a low temperature fluid through the passage ducts 14, 46 of the internal fluid passage 11, the thermoelectric element assembly can be assembled. Electric power is generated by the temperature difference acting on the thermoelectric element assembly 5. At this time, since the outer surface of the thermoelectric element assembly 5 is exposed to the external fluid duct 10, 10' side,
The outer part of the thermoelectric element assembly 5 is no longer restrained in any way, and this part becomes free from thermal deformation, thereby preventing damage to the thermoelectric elements 1, 2, etc. due to thermal stress caused by temperature differences. At the same time, it is possible to prevent a decrease in heat transfer performance due to this damage and a decrease in power generation capacity due to instability.

Further, according to the present invention, since the outer surface of the thermoelectric element assembly 5 is exposed to the external fluid duct 10 side, the outer surface of the thermoelectric element assembly 5 is directly exposed to the external fluid A, and the inner and outer surfaces of the thermoelectric element assembly 5 are exposed to the external fluid A. It is possible to efficiently incorporate the temperature difference between the outside fluids and improve power generation efficiency.

[Brief explanation of the drawing]

FIG. 1 is a partially cut-away plan view of one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the same, FIG. 3 is a structural explanatory diagram of another embodiment of the present invention, FIG. 4 is a structural explanatory diagram of another embodiment of a thermoelectric element assembly, FIG. 5 is a structural explanatory diagram of another embodiment of the present invention, FIG. 6 is a perspective view of a thermoelectric element assembly, FIG. 7 is a structural explanatory diagram of a conventional thermoelectric power generation device, and FIG. 8 is a longitudinal sectional view of another embodiment of the present invention.
FIG. 9 is a perspective view of the same. 1 is a P-type semiconductor, 2 is an N-type semiconductor, 3, 4,
4' is a metal piece, 5 is a thermoelectric element assembly, 10, 1
0' is an external fluid duct, 11 is an internal fluid duct, 14 and 46 are passage ducts, 15 and 47 are fins, 26 and 27 are molds, 30 is a buffer section, 3
2 is a water tank, 33 is an evaporation tube, and 40 is a steam chamber.

Claims (1)

[Scope of utility model registration request] External fluid duct 10, 1 through which external fluid A flows
0', a passage duct 14 through which internal fluid B flows,
A thermoelectric element assembly 5 having an electric terminal 28 for taking out the generated power is fixed to the outer surface of the passage ducts 14 and 46 so that the inner surfaces thereof are closely joined, and the outer surface is A thermoelectric generator characterized in that it is exposed in an external fluid.