JPH0719613B2 - Fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to cooling of a thermoelectric battery, and more particularly to the structure of a cooling pipe embedded in a cooling plate.

(Prior Art) A thermoelectric battery is a device that directly converts energy contained in a thermoelectric material into electric energy. In a thermoelectric battery, a pair of porous electrodes are usually placed across an electrolyte, and a thermogenic gas such as hydrogen is brought into contact with the back surface of one electrode and an oxidant gas such as oxygen is brought into contact with the back surface of the other electrode. Let By utilizing the electrochemical reaction occurring at this time, electric energy is taken out from between both electrodes.

FIG. 3 shows the structure of an actual cell. The unit cell is composed of a pair of electrodes, which are an anode electrode 2 which is a heat electrode and a cathode electrode 2a which is an oxidant electrode, with the electrolyte layer 1 interposed therebetween, and each of the adjacent unit cells is separated by a separator 4.

Since the voltage generated by the thermoelectric battery is as low as 1 V or less than that of the unit cell, normally 400 to 500 unit cells are stacked as shown in FIG. 4 to obtain a desired high voltage.

When stacking, since the above reaction is an exothermic reaction, a cooling plate 7 is provided between several unit cells 6 in order to prevent temperature rise of the cells.
Is installed and an upper end cooling plate 5 and a lower end cooling plate 8 for the stacked unit cells are installed to take out heat generated from the thermoelectric battery to the outside.

Therefore, as shown in FIG. 5, the cooling plate 7 is usually made of a compression molded graphite resin composition, and a plurality of insulation-treated cooling tubes 9 of about 3 to 6 mmφ are embedded at equal intervals. There is. Water, organic solution, etc. are used as the refrigerant,
It is introduced through the refrigerant inlet pipe 10 and discharged through the refrigerant outlet pipe 14.

(Problems to be solved by the invention) There are two types of cooling, a single-phase flow system and a two-phase flow system, but two-phase cooling is possible because the refrigerant flow rate is small and steam is required in the power plant. Flow cooling method is adopted. In this case, in the laminated battery configured as shown in Fig. 4, the cooling plate 7 (Fig. 5) inserted between the cells has heat input from the upper and lower batteries, but the upper end is cooled. The plate 5 and the lower end cooling plate 8 only have heat input from one side, and the amount of heat input is halved.

Therefore, with these two cooling plates, boiling does not start in the cooling pipe, and a single-phase flow state with less pressure loss than other cooling plates (provided between cells) in a two-phase flow state is obtained. turn into. Such non-uniformity of the flow rate between the cooling plates is not preferable in terms of cooling performance, and there is a problem that the temperature distribution of the battery becomes non-uniform and the life is shortened.

The present invention has been made to solve the above problems, and an object thereof is to provide a cooling medium flowing through a cooling pipe of a cooling plate provided between the upper and lower ends of a thermoelectric battery stack and the unit cells. Is to provide a uniform two-phase flow, and to provide a thermoelectric battery capable of excellent battery cooling.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a plurality of unit cells each having a pair of electrodes of a heating agent electrode and an oxidizing agent electrode arranged with an electrolyte layer sandwiched therebetween are laminated. A thermoelectric battery that constitutes a thermoelectric battery laminate and has a cooling plate between the upper and lower ends of the thermoelectric battery laminate and the unit cells, and performs two-phase flow cooling by latent heat of vaporization of a cooling medium flowing through the cooling plate, It is characterized in that the number of cooling pipes embedded in the cooling plates at the upper and lower ends of the thermoelectric battery laminate is half the number of cooling plates provided between the cells of the thermoelectric battery laminate. .

(Operation) When cells are stacked and cooling plates are provided between both ends of the cells and between the cells, the refrigerant bodies flowing through the cooling plates are non-uniform so that the two-phase flow state is equal in each cooling plate. Lost

(Example) Before describing an example of the present invention, the principle of the thermoelectric battery will be described.

A molten carbonate, an alkaline solution, an acid solution or the like is used as the electrolyte, and the principle of a typical thermoelectric battery using phosphoric acid as the electrolyte will be described.

In FIG. 2, the electrolyte layer 1 is a fibrous sheet or a mineral powder impregnated with phosphoric acid. An anode electrode 2 and a cathode electrode 2a are arranged on both sides of the electrolyte layer 1.
Both electrodes 2 and 2a are formed of a porous member made of a carbonaceous member. A platinum catalyst is usually applied to the side of the electrolyte layer 1 of each of the electrodes 2 and 2a. The anode electrode 2 and the cathode electrode 2a are respectively provided with a heat source gas chamber 3 in which a heat source gas flows and an oxidant gas chamber 3a in which an oxidant gas flows, on opposite sides of the electrolyte layer 1. Generally, in a phosphoric acid type thermal battery, the thermal gas is hydrogen and the oxidizing gas is oxygen in the air.

In the phosphoric acid type thermal battery having the above structure, the hydrogen gas in the gas flowing into the thermal gas chamber 3 diffuses into the void of the porous anode electrode 2 and reaches the catalyst. The hydrogen gas is dissociated into hydrogen ions and electrons by the action of the catalyst. That is, the reaction formula is as follows.

H ₂ → H ⁺ + 2e Next, hydrogen ions H ⁺ enter the electrolyte layer 1 and migrate toward the cathode electrode 2a due to concentration diffusion. On the other hand, the electrons e flow into the anode electrode 2. At the cathode electrode 2a, hydrogen ions H ⁺ that have migrated from the anode electrode 2 and oxygen O ₂ in the air that has flowed into the oxidant gas chamber 3a diffuse into the voids of the porous cathode electrode 2a. The diffused oxygen O ₂ and the electron e and hydrogen ion H ⁺ returning from the anode electrode 2 to the battery through the external electric load R cause the following reaction on the catalyst surface.

4H ⁺ ＋ 4e ＋ O ₂ → 2H ⁺ ₂ O In this way, chemical energy can be extracted as electric energy in the form of electrons flowing through an external electric load.

FIG. 1 shows an example of the structure of a cooling plate used for the upper and lower ends of the laminated battery according to the present invention.

That is, in the cooling plates 5 and 8 of the embodiment of the present invention, the number of cooling pipes of the cooling plate 7 inserted between the unit cells is halved, and the connection of the inlet and outlet of the refrigerant is configured in the same manner.

In the laminated battery configured as above, the flow rate to the cooling plates at the upper and lower ends is approximately 1/2 and the heat inflow amount is also 1/2. Therefore, the flow rate per cooling pipe, flow condition, outlet steam amount, etc. It is almost the same as that inserted between the cell stacks. As a result, a uniform cell cooling effect can be obtained.

Thus, according to one embodiment of the present invention, the upper end of the laminated battery,
By making the number of the cooling tubes of the lower end cooling plate about half of that of the cooling plates between the stacked layers, it is possible to eliminate the unevenness of the refrigerant flow rate in the cooling tubes and obtain a good battery cooling effect.

〔The invention's effect〕

As described above, according to the present invention, the number of cooling pipes embedded in the cooling plates at the upper and lower ends of the thermal battery stack is half the number of cooling plates provided between the unit cells of the fuel cell stack. Since the fuel cell stack is configured as described above, not only can the fuel cell stack be uniformly cooled, but each cooling medium is in the two-phase flow state equally, so that the steam required for the power plant can be stably obtained. That is, the temperature distribution can be made uniform, and a long-life and highly reliable fuel cell can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of the upper and lower cooling plates according to the present invention, FIGS. 2 and 3 are diagrams for explaining the principle of a heat-charged battery and the structure of a single battery, and FIG. FIG. 5 is a diagram showing an example of a laminated structure of a fuel cell, and FIG. 5 is a diagram showing a cooling plate provided between the laminated cells. 1 ... Electrolyte layer, 2 ... Anode electrode 2a ... Cathode electrode, 3 ... Heat agent gas chamber 3a ... Oxidant gas chamber, 4 ... Separator 5 ... Upper end cooling plate, 6 ... Single cell 7 ...... Cooling plate inserted into laminated battery, 8 ...... Cooling plate at lower end 9 ...... Cooling pipe, 10 ...... Refrigerant inlet pipe 11 ...... Refrigerant outlet pipe

Claims (1)

[Claims] 1. A fuel cell stack is constructed by stacking a plurality of unit cells each having an integrated electrode of a fuel electrode and an oxidizer electrode with an electrolyte layer sandwiched between them. In a thermochemical battery having a cooling plate between unit cells and performing two-phase flow cooling by the latent heat of vaporization of a cooling medium flowing through the cooling plate, a cooling pipe embedded in the cooling plate at the upper and lower ends of the thermoelectric battery stack. Is half the number of the cooling plates provided between the unit cells of the thermoelectric battery laminate, the thermoelectric battery.