JPH078155B2 - Power generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power generation device of a direct power generation system that directly converts thermal energy into electrical energy.

(Prior Art) A power generation system targeted by the present invention is called an alkali metal thermoelectric conversion system or a sodium heat engine, and the power generation principle was proposed by JT Cummer et al. In 1969 (US Pat. No. 3,458,356). This power generation method has a large output per electrode area of the power generation device, a large output per unit weight, can achieve a relatively high energy conversion efficiency, can freely select the power generation scale, and can support any heat source, It has many advantages such as no operating part for direct power generation, no vibration and noise, and high reliability.

Some power generation devices using this power generation principle have been reported so far. FIG. 4 shows a conventional power generator. A solid electrolyte 1 such as β-alumina or β ″ -alumina is provided in the device, a positive electrode film 2 is provided on the + side of the solid electrolyte 1, and a positive electrode film 2 is opposed thereto. Then, a high temperature side heat source 3 is provided respectively, a condenser 4 and a circulation pump 5 are provided below the high temperature side heat source 3, and an external circuit 6 connecting the positive electrode film 2 and the solid electrolyte 1 on the opposite side is provided. There is.

The working medium such as sodium is brought into a liquid phase state by the capacitor 4, and then is supplied as it is to the solid electrolyte 1 on the side opposite to the positive electrode film 2 in the liquid phase state. As another method, as previously proposed by the present inventors, the working medium in the liquid phase is evaporated and supplied to the solid electrolyte 1 on the side opposite to the positive electrode film 2 in the gas phase (Japanese Patent Laid-Open No. Hei 10 (1999) -135242). 1-97182).

The working medium such as sodium supplied to the left side of the solid electrolyte 1 (on the side opposite to the electrode film 2) releases electrons at the electrolyte interface and is ionized, and moves to the positive electrode film 2 side. At the same time as it is received and reduced, it is evaporated by the heat from the high temperature side heat source 3. Further, the working medium in the vapor phase is supplied to the condenser 4 through the space between the positive electrode film 2 and the heat source 3 on the high temperature side, is condensed there, and the working medium in the liquid phase is in the initial state by the circulation pump 5. Is supplied to the solid electrolyte 1 on the side opposite to the positive electrode film 2. By configuring such a closed cycle, it is possible to generate DC power in the external circuit 6.

(Problems to be Solved by the Invention) One of the major problems of the alkali metal thermoelectric conversion method lies in the method of supplying thermal energy to the electrode film portion, and in the conventional device as described above, the high temperature side heat source 3 is used. The method of supplying radiant heat to the electrode film 2 employs radiant heating. However, since a gas-phase working medium passage is provided between the electrode film 2 and the high temperature side heat source 3, it is necessary to provide a gap between the electrode film 2 and the high temperature side heat source 3, and therefore the heat source 3 The temperature difference between the temperature and the electrode film 2 becomes large. For example, in order to set the surface of the electrode film 2 to 800 ° C., it is necessary to set the temperature of the high temperature side heating surface to 1100 ° C. or higher. Therefore, it is necessary to use an expensive material that has a large loss of thermal energy and is durable at high temperature, and to consider the positional relationship between the electrode film and the heat source on the high temperature side, which is a constraint in designing the system. There are problems such as many conditions.

When the electrode film 2 is heated by radiant heating from the high temperature side heat source 3, the heating of the surface of the electrode film 2 becomes non-uniform, which may cause damage to the solid electrolyte 1 as well as the electrode film. Since the heating of the two surfaces is non-uniform, there is a problem in that there is a difference in evaporation of the working medium on the two surfaces of the electrode film, making it difficult to operate under optimum operating conditions.

(Means for Solving Problems) In order to solve the above problems, in the present invention, an electrode part is provided on the + side of the solid electrolyte, a high temperature part is provided facing the electrode part, and the working medium is the solid electrolyte. Ionize the inside and let it pass,
In a power generator that receives and reduces electrons at the electrode part and at the same time evaporates by the heat from the high temperature part and circulates and uses the power generator, a porous heat transfer body is interposed between the electrode part and the high temperature part. It is a proposal.

Here, a medium having a high ionic conductivity of the solid electrolyte is selected as the working medium. For example, β-alumina or β ″
When using a solid electrolyte such as alumina, it is possible to use alkali metals such as sodium, potassium and cesium, or mercury, and it is also possible to use other working media by selecting a solid electrolyte. Is.

As the material for the porous heat transfer material, either an insulating material or a conductive material can be used, but nickel, nickel, in consideration of being capable of withstanding high temperatures and not corroding the working medium, Refractory metals such as molybdenum, tungsten, niobium, rhenium, and tantalum are used, but it is also possible to use a composite material of a porous material made of an insulating material. Further, as the shape of the porous heat transfer body, a shape having a high porosity that does not interfere with the evaporation of the working medium from the electrode film can be adopted.

(Operation) As described above, in the present invention, since the porous heat transfer body is interposed between the electrode part and the high temperature part, the heat of the high temperature part is transferred to the electrode part through the heat transfer body. The working medium evaporated in the electrode portion by this heat is sent to the condenser through the porous passage of the heat transfer body.

As described above, in the present invention, the heat of the high temperature portion is transferred to the electrode portion by heat conduction, so that the temperature difference between the high temperature side and the electrode portion or the portion of the solid electrolyte can be made small, and therefore the power generation efficiency can be improved. Becomes Further, according to the present invention, it is possible to suppress the heat loss by lowering the temperature on the high temperature side, and it is possible to use an inexpensive material. Furthermore, the positional relationship between the heating surface on the high temperature side, the electrode portion, and the solid electrolyte is compared. It can be set freely and is very advantageous in system design.

Further, when the porous heat transfer body is made of a conductive material such as nickel, the heat transfer body itself becomes a part of the electrode part,
An external circuit lead wire can be connected to this. That is, in the conventional device shown in FIG.
However, since the thickness of the electrode film 2 is on the order of micron, it is difficult to connect the lead wire for taking out the current generated from the entire surface of the electrode film with a small resistance, and the connection is once made. Even though there is a problem such as disconnection during operation, the thickness of the heat transfer body used in the present invention is of the order of centimeters, and the lead wire can be connected easily and surely.

(Example) Hereinafter, the present invention will be described in detail based on an illustrated example.

FIG. 1 shows an embodiment of the present invention. As in FIG. 4, 1 is a solid electrolyte such as β-alumina or β ″ -alumina, and 2 is a positive electrode provided on the + side of the solid electrolyte 1. Electrode film,
3 is a high temperature side heat source provided facing the positive electrode film 2;
Is a condenser, 5 is a circulation pump, and 6 is an external circuit.

A heat transfer body 7 made of porous nickel or the like is interposed between the electrode film 2 and the high temperature side heat source 3, and one lead wire of the external circuit 6 is connected to the heat transfer body 7.

Sodium is used as the working medium. Therefore, as described in FIG. 4, when the solid electrolyte 1 ionizes sodium, it moves toward the electrode film 2 and electrons are given to the electrode film 2 to become sodium again. At the same time, the heat transmitted from the high temperature side heat source 3 through the heat transfer body 7 evaporates, and this vapor is sent to the condenser 4 below through the porous passage of the heat transfer body 7.

In this way, a direct current can be generated in the external circuit 6 in the same manner as described with reference to FIG. 4, but in the present invention, the heat from the high temperature side heat source 3 is transferred to the electrode film 2 by the heat transfer body 7. Therefore, the heating surface on the high temperature side, the electrode film 2, the solid electrolyte 1
It is possible to reduce the temperature difference in the portion of, and to improve the power generation efficiency.

FIG. 2 shows another embodiment. In this case, a cylindrical solid electrolyte 1 is used, an electrode film 2 is provided on the periphery of the cylindrical solid electrolyte 1, and the outer periphery thereof is further provided. A porous heat transfer body 7 made of nickel and a high temperature side heat source 3 are respectively provided, and the tip of the passage of the working medium from the circulation pump 5 is made to face the inside of the cylindrical solid electrolyte 1. There is.

Other parts are the same as those in FIG. 1 and the same reference numerals are used and the description thereof is omitted. However, in this embodiment, unlike FIG. 1, the electrode film provided on the periphery of the cylindrical solid electrolyte 1 is different. Two
Is heated from the high temperature side heat source 3 provided on the outer periphery thereof via the heat transfer body 7, so that the electrode film 2 can be effectively heated with relatively small heat energy. Therefore, the temperature difference between the high temperature side heating surface and the electrode surface can be reduced.
For example, in the case of the conventional radiant heating method for this shape,
To make the electrode surface 800 ° C, the heating surface on the high temperature side is 1100
Although it was necessary to set the temperature above ℃, in the embodiment shown in FIG. 2, it is sufficient that the high temperature side heating surface temperature is about 860 ℃.

FIG. 3 shows an embodiment in which FIG. 2 is further improved. In this case, the heat transfer body 7 is brought into contact with the inner wall of the cylindrical high temperature side heat source 3
A cylindrical solid electrolyte 1 is arranged, and a circulation pump 5 is provided.
The working medium is supplied to the inside of each cylindrical solid electrolyte 1. The other operations are the same as those in the above-mentioned embodiment, so the description thereof is omitted here.

In FIG. 3, the electrode surface can be heated more efficiently and uniformly than in FIG. 2, so that damage to the solid electrolyte due to nonuniform heating of the conventional electrode surface can be prevented. Since the electrode surface is heated uniformly, the device can be operated under optimum operating conditions.

(Effects of the Invention) In summary, according to the present invention, by interposing a porous heat transfer body between the electrode part and the high temperature part, the high temperature side heating surface and the electrode surface can be compared with the conventional radiant heating method. The temperature difference between the two can be significantly reduced, and the thermal energy can be effectively used. Moreover, since it is possible to efficiently generate electricity with relatively small heat energy, it is possible to widen the range of application of the alkali metal thermoelectric conversion method which is the object of the present invention.

Further, according to the present invention, it is possible to reduce the heat loss by lowering the temperature on the high temperature side, it becomes possible to use an inexpensive material, and there is also a cost reduction effect.

Further, according to the present invention, since the electrode surface can be heated uniformly, the device can be operated under optimum operating conditions without causing damage to the solid electrolyte.

Further, according to the present invention, there are few restrictions on the positional relationship between the heating surface on the high temperature side, the electrode, and the solid electrolyte, as compared with the conventional radiant heating method, and therefore the degree of freedom in system design can be increased.

[Brief description of drawings]

FIG. 1 is a schematic side view of a power generator showing an embodiment of the invention, FIG. 2 is a schematic side view of a power generator showing another embodiment of the invention, and FIG. 3 is a further side view of the invention. FIG. 4 is a schematic plan view of a power generator showing another embodiment, and FIG. 4 is a schematic side view of a conventional power generator. In the figure, 1 is a solid electrolyte, 2 is an electrode film, 3 is a high temperature side heat source,
7 is a porous heat transfer body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Honda 1-4-1, Umezono, Tsukuba-shi, Ibaraki Electronic Technology Research Institute (56) Reference JP-A-60-249879 (JP, A)

Claims (2)

[Claims] 1. An electrode part is provided on the + side of the solid electrolyte, and a high temperature part is provided opposite to the electrode part. The working medium is ionized in the solid electrolyte to pass therethrough, and electrons are received and reduced at the electrode part. At the same time, in a power generation device that is circulated for use by being evaporated by heat from a high temperature part, a power generation device characterized in that a porous heat transfer body is interposed between the electrode part and the high temperature part. 2. The power generator according to claim 1, wherein the porous heat transfer body is made of a conductive material.