JPH05231242A - Hydrogen storage alloy having compound thermoelectric element - Google Patents

Abstract

PURPOSE:To provide a hydrogen storage alloy having a compound thermoelectric element which consistently performs starting and operation of various kinds of devices, and supplement of hydrogen thereto without necessitating a large scale heating/pressure reducing device or cooling/pressurizing device. CONSTITUTION:A hydrogen storage alloy M stores hydrogen (H2) by cooling and pressurizing, and discharges hydrogen (H2) by heating and pressure reducing. A thermoelectric element 4 which is composed of a p-type semiconductor 4a and an n-type semiconductor 4b is fixed to the hydrogen storage alloy M through an insulator 2. A specified voltage 6 is applied to the thermoelectric element 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen storage alloy having a composite thermoelectric element, and more particularly to a hydrogen having a composite thermoelectric element applicable to an engine, a heat storage device, a compressor, a cooling / refrigerating device, a hydrogen isotope separation device and the like. Regarding storage alloys.

[0002]

2. Description of the Related Art In recent years, attention has been paid to the application of hydrogen storage alloys to various devices. Many metals produce hydrides, but since they stabilize in the hydride state, they do not dissociate and do not release hydrogen even when heated or the pressure is lowered. However, some alloys relatively easily form hydrides and occlude a large amount of hydrogen, and the hydrides are dissociated and a large amount of hydrogen is released by slight heating or reduced pressure. This type of alloy is called a hydrogen storage alloy. For example, rare earth alloys (La
Ni ₅ ), titanium-based alloys (FeTi, etc.), and magnesium-based alloys (Mg ₂ Ni, etc.) have been put to practical use.

That is, the hydrogen storage alloy stores and releases hydrogen by the mechanism shown in FIG. As shown in the figure, when the hydrogen storage alloy M is cooled, hydrogen H ₂ is stored, the reaction proceeds in a direction in which the hydrogen storage alloy M generates heat, and the hydrogen storage alloy MH ₂ stores hydrogen. vice versa,
When the hydrogen storage alloy MH ₂ that has stored hydrogen is heated, the reaction proceeds in a direction in which the hydrogen storage alloy M absorbs heat, and hydrogen H ₂ is released.

As described above, the hydrogen storage alloy does not release hydrogen unless it is heated, so that it can be safely transferred in a metal state in which hydrogen is stored. In addition, even if hydrogen is burned, only water is produced, so no carbon dioxide is generated and it is a fuel that is friendly to the global environment. Focusing on these points, in addition to fuel tanks for hydrogen engines for vehicles,
Development of various devices utilizing the hydrogen storage / release mechanism of hydrogen storage alloys is underway.

For example, a relatively lightweight magnesium alloy is used in the fuel tank of the hydrogen engine for vehicles, and the hydrogen storage alloy is heated by the exhaust heat of the engine cooling water to store the hydrogen stored in the alloy. It is designed to be released. When the piston and rotor of the hydrogen engine are driven by the pressure generated by the combustion of hydrogen released from the hydrogen storage alloy, the power equivalent to that of a gasoline engine is generated.

[0006]

The various techniques to which the conventional hydrogen storage and storage is applied have the following problems.

When hydrogen storage / storage is applied to the fuel tank of the vehicle hydrogen engine as described above, hydrogen is consumed in the hydrogen engine, so it is necessary to supply hydrogen from the hydrogen station to the hydrogen storage / storage as the fuel tank. However, at that time, it is necessary to provide a cooling facility such as water cooling for cooling the hydrogen storage and storing hydrogen therein. But,
The conventional fuel tank has a problem that such a cooling facility is not provided.

Further, since the hydrogen storage alloy is heated by the exhaust heat of the engine cooling water to release the absorbed hydrogen in the alloy, this exhaust heat cannot be utilized at the time of starting the engine. Therefore, there is a problem that a hydrogen storage alloy that releases hydrogen at room temperature must be provided as a sub-fuel tank separately from a magnesium-based alloy that releases hydrogen at about 250 ° C.

Further, when it is applied to various other devices, there is a problem that the hydrogen storage alloy requires a large-scale heating / decompression device or cooling / pressurization device.

In view of the above problems, an object of the present invention is to eliminate the need for a large-scale heating / decompression device or cooling / pressurization device,
It is an object of the present invention to provide a hydrogen storage alloy which is a composite of thermoelectric elements capable of consistently starting, operating, and supplying hydrogen to various devices.

[0011]

According to the hydrogen storage alloy compounding the thermoelectric element according to the present invention, the above-mentioned object is to achieve cooling and
In a hydrogen storage alloy that absorbs hydrogen by pressurization and releases hydrogen by heating / decompression, a thermoelectric element formed of a p-type semiconductor and an n-type semiconductor is fixed to the hydrogen storage alloy via an insulator, The thermoelectric element is characterized by being loaded with a predetermined voltage.

Further, in the above structure, a predetermined voltage is applied to the thermoelectric element so that the forward and reverse electrodes can be freely converted.

Further, the hydrogen storage alloy is characterized in that a pipe is provided for allowing a fluid to pass therethrough.

[0014]

According to the above structure, the thermoelectric element formed of the p-type semiconductor and the n-type semiconductor is fixed to the hydrogen storage alloy via the insulator. A predetermined voltage is applied to this thermoelectric element. Therefore, the thermoelectric element heats or cools the hydrogen storage alloy.

In particular, when a predetermined voltage is applied to the thermoelectric element so that the forward and reverse electrodes can be freely converted, the following heating / cooling operation becomes possible.

First, when it is desired to occlude hydrogen H ₂ in the hydrogen occluding alloy, when the predetermined voltage is electrode-adjusted and a current is passed in one direction of the thermoelectric element, for example, electrons and holes are converted into the hydrogen. Heat is taken from the storage alloy and carried to the thermoelectric element side. As a result, the temperature of the hydrogen storage alloy becomes lower than the temperature of the thermoelectric element. Therefore, the hydrogen storage alloy is cooled and becomes a hydrogen storage alloy that has stored hydrogen. this is,
It is applied as a hydrogen supply technology for various devices.

On the other hand, when it is desired to release hydrogen H ₂ from this hydrogen storage alloy, if the predetermined voltage is electrode-adjusted and a current is passed in the other direction of the thermoelectric element, for example, electrons and holes will become Heat is taken from the thermoelectric element side and carried to the hydrogen storage alloy. As a result, the temperature of the hydrogen storage alloy becomes higher than the temperature of the thermoelectric element. Therefore, the hydrogen storage alloy is cooled and hydrogen H ₂ is released therefrom. This is applied as a power starting technique for various devices.

Further, since the hydrogen storage alloy is provided with a pipe for allowing a fluid to pass therethrough, cooling water or the like heated by engine exhaust heat or the like can be passed therethrough, and the exhaust gas during power operation can be passed. It is possible to actively utilize heat.

That is, since the hydrogen storage alloy is provided with the thermoelectric element, a large-scale heating / decompression device or cooling / pressurization device is not required. Moreover, in addition to this, by positively utilizing the exhaust heat, it is possible to consistently perform the start-up / operation / hydrogen supply of various devices.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a hydrogen storage alloy compounding a thermoelectric element according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 (a) is a schematic view showing a first embodiment of a hydrogen storage alloy in which a thermoelectric element according to the present invention is combined. As shown in the figure, the hydrogen storage alloy M constituting the hydrogen storage alloy 1 in which the thermoelectric elements of this embodiment are combined has, for example, a rectangular parallelepiped outer shape. The hydrogen storage alloy M is formed by adjusting a metal that easily forms a hydride and a metal that hardly forms a hydride at an appropriate composition ratio.
As a metal that easily forms this hydride, for example,
Lanthanum (La), titanium (Ti), zirconium (Z
In the case of a simple metal such as v), there is a metal that absorbs a large amount of hydrogen and forms a stable hydride. On the other hand, as a metal that hardly forms a hydride, iron (Fe), nickel (Ni),
There is a metal that hardly absorbs hydrogen under normal conditions when it is a simple metal such as cobalt (Co). The hydrogen storage alloy M is prepared by adjusting these elemental metals at an appropriate composition ratio,
The crushed alloy is degassed in vacuum, and then gradually cooled in hydrogen at several tens of atmospheric pressure to absorb hydrogen to produce the alloy. Specifically, the material of the hydrogen storage alloy M is, for example, a rare earth alloy (L
aNi _5, etc.), titanium-based alloys (FeTi, etc.), magnesium-based alloys (Mg ₂ Ni, etc.), etc. are adopted. still,
In the present embodiment, the hydrogen storage alloy M is molded so as to have a rectangular parallelepiped outer shape, but the shape is not limited to this, and the hydrogen storage alloy M is molded into an appropriate shape according to the applied device.

Further, on one surface of the hydrogen storage alloy M, a flat plate of the insulator 2 formed of, for example, a heat resistant synthetic resin or ceramics is polymerized in a clad shape. This insulator 2 does not necessarily have to be a plate material,
For example, an insulating paint may be applied to one surface of the hydrogen storage alloy M.

Further, on the side of the insulator 2 of the hydrogen storage alloy M, another plate-like insulator 3 is provided at an appropriate interval from the insulator 2.

A plurality of thermoelectric elements 4 are provided between the insulators 2 and 3. Specifically, in these thermoelectric elements 4, the same number of p-type semiconductors 4a and n-type semiconductors 4b are alternately provided along the surfaces of the insulators 2 and 3. Adjacent p-type semiconductor 4a and n-type semiconductor 4b
Are joined so as to form a U-shaped thermoelectric element 4 by an adhesive 5 having heat resistance and conductivity such as a brazing material. Further, the bonding between the p-type semiconductor 4a and the n-type semiconductor 4b by the adhesive 5 is alternated between the surface of the insulator 2 and the surface of the insulator 3, so that the thermoelectric element 4 as a whole has a wavy shape. Are connected in series. Where p
For example, FeSi ₂ or the like is used as the type semiconductor 4a, and CoSi or the like is used as the n-type semiconductor 4b.

A constant voltage power source 6 having a predetermined voltage is applied to the p-type semiconductor 4a and the n-type semiconductor 4b located at both ends of the thermoelectric element 4 via the adhesive 5, respectively.
Are connected and loaded by the electric wiring 7. The constant voltage power source 6 is composed of a first power source 6a and a second power source 6b having different electrode directions. Then, these first power source 6
a and the second power source 6b are connected via switches 8a and 8b provided on the electric wiring 7, and by switching the switches 8a and 8b, a load applied to the thermoelectric element 4 is converted into a forward and reverse electrode. I'm free. The above switch 8
If a and 8b are configured as shown in FIG. 1 (b), the load applied to the thermoelectric element 4 can be converted into the positive and negative electrodes by one constant voltage power source 6.

Specifically, when the hydrogen storage alloy 1 in which the thermoelectric elements of this embodiment are combined is applied to a vehicle, the following two examples can be considered. First, as shown in FIG. 2, while the hydrogen storage alloy M is being cooled, hydrogen H ₂ is replenished from the hydrogen stand 9 to obtain hydrogen storage alloy MH ₂ that has stored hydrogen, and this is heated to release hydrogen H ₂ . Let Then, it is conceivable that the released hydrogen H ₂ is burned to operate a piston (not shown) or the like. Also, as shown in FIG.
It is conceivable to supply hydrogen H ₂ surplus from the operation of the piston or the like to the fuel cell 10 mounted on the vehicle.

Next, the operation of the hydrogen storage alloy 1 in which the thermoelectric elements of the first embodiment are combined will be described by taking as an example the case of using it as a fuel tank of a hydrogen engine for a vehicle.

First, the hydrogen storage alloy 1 as a fuel tank
When it is desired to store hydrogen H ₂ in the fuel cell, that is, when replenishing hydrogen H ₂ from the hydrogen stand, as shown in FIG. 1, the first power source 6 is operated by the switches 8a and 8b.
When a is connected and a current flows in the a direction, electrons and holes take heat from the hydrogen storage alloy M and carry it to the thermoelectric element 4 side. As a result, the temperature T of the hydrogen storage alloy M is
₁ (° C.) and the temperature T ₂ (° C.) of the thermoelectric element 4 are T
The relationship is ₁ <T ₂ . Therefore, the hydrogen storage alloy M is cooled and becomes hydrogen storage alloy MH ₂ which has stored hydrogen H ₂ .

Further, hydrogen H is obtained from this hydrogen storage alloy MH _{2.
When 2 is} to be released, that is, when the hydrogen engine is started, when the second power source 6b is connected by the switches 8a and 8b and a current in the b direction is passed, electrons and holes are generated in the thermoelectric element. Heat is taken from the 4 side and carried to the above hydrogen storage alloy M. As a result, the temperature T of the hydrogen storage alloy M is
₁ (° C.) and the temperature T ₂ (° C.) of the thermoelectric element 4 are T
The relationship is ₁ > T ₂ . Therefore, the hydrogen storage alloy MH ₂ is heated, and hydrogen H ₂ is released from this, and this hydrogen H
_The hydrogen engine can be started by driving the piston or the like with the pressure generated by burning the ₂ . in this case,
When the hydrogen engine is started and the temperature rises to the level at which engine exhaust heat can be used, the exhaust heat can heat the hydrogen storage alloy MH ₂ , and at that time, the load on the thermoelectric element 4 is released by the switches 8a and 8b. To do.

Further, FIGS. 4 and 5 are explanatory views showing the driving operation states at the time of hydrogen replenishment and at the time of engine start described above. First, when replenishing hydrogen, as shown in FIG. 4, the first power source 6a is turned on by the switches 8a and 8b.
After starting 11 of the energization, the temperature of the hydrogen storage alloy MH ₂ which has stored hydrogen is measured 12. This hydrogen storage alloy M
When the temperature of H ₂ is not cooled to the predetermined temperature, the energization is continued 11a. On the other hand, the above hydrogen storage alloy M
If the temperature of H ₂ has been cooled to the specified temperature,
The injection of hydrogen H ₂ is started 13 from the hydrogen station.
Then, after confirming 14 that the predetermined injection amount has been reached by the gas meter of the hydrogen station, the energization of the first power source 6a is turned off 15 by the switches 8a and 8b.

On the other hand, when the engine is started, as shown in FIG. 5, after the energization 16 of the second power source 6b is started 16 by the switches 8a and 8b, the temperature of the hydrogen storage alloy MH ₂ which has stored hydrogen is And measure the pressure of hydrogen H ₂ . When the temperature of the hydrogen storage alloy MH ₂ is not heated to a predetermined temperature, or when the pressure of the hydrogen H ₂ is not a predetermined value, energization is continued 16a. On the other hand, when the temperature of the hydrogen storage alloy MH ₂ is heated to a predetermined temperature and the pressure of the hydrogen H ₂ has a predetermined value, the hydrogen engine is started 18. After starting this engine, the temperature of the hydrogen storage alloy MH ₂ which has stored hydrogen and the pressure of hydrogen H ₂ are measured 19. When the temperature of the hydrogen storage alloy MH ₂ is not heated to a predetermined temperature or when the pressure of the hydrogen H ₂ is not a predetermined value, the second power source 6b is turned on by the switches 8a and 8b. It is the state of. On the other hand, when the temperature of the hydrogen storage alloy MH ₂ is heated to a predetermined temperature and the pressure of the hydrogen H ₂ is a predetermined value, the second power source 6b is turned off by the switches 8a and 8b 20b. To do. After starting the engine 18, the measurement 19 of the temperature of the hydrogen storage alloy MH ₂ which has stored hydrogen and the pressure of the hydrogen H ₂ is continued, and the energization ON / OFF 20a, 20b of the switches 8a, 8b is controlled. Repeated.

FIG. 6 is a schematic view showing a second embodiment of the hydrogen storage alloy compounding the thermoelectric element according to the present invention. As shown in the drawing, the hydrogen storage alloy 21 in which the thermoelectric element of this example is composited is provided in each space located between the p-type semiconductor 4a and the n-type semiconductor 4b constituting the thermoelectric element 4, Pipes 22 for passing a fluid are respectively provided. Each of the pipes 22 is covered with an insulating coating layer 23 such as synthetic resin. The pipes 22 covered with the insulating coating layer 23 are provided so as to be in contact with the insulators 2, respectively.

The second embodiment basically has the same operation and effect as the first embodiment, but in the second embodiment in particular, the provision of the pipe 22 makes it possible to The engine cooling water can be positively passed. After the hydrogen engine is started, the hydrogen storage alloy MH ₂ can be heated by the exhaust heat of the engine cooling water to release the stored hydrogen H ₂ in the alloy MH ₂ .

Further, the hydrogen storage alloys 1 and 21 in which the thermoelectric elements of the first and second embodiments are combined can be applied to various devices other than vehicles, but the simple concept thereof will be described with reference to known documents. ..

First, as shown in FIG. 7, the hydrogen storage alloy M
Hydrogen H ₂ released from H ₂ can be converted into electric energy and mechanical energy. These energy conversions can be applied to the following various devices.

FIG. 8 shows an example of application to a heat storage device. As shown, in the heat storage device 30,
During the daytime, the hydrogen storage alloy MH ₂ is heated by solar heat, and the hydrogen H ₂ released therefrom is stored in the cylinder 31. On the other hand, at night, hydrogen H ₂ is returned from the cylinder 31 to the hydrogen storage alloy MH _{2 so} as to store it and generate heat. It is configured to make hot water by using this heat dissipation and use it in a bath or the like.

An example of application to a compressor is low temperature /
It is configured to store hydrogen H ₂ in the hydrogen storage alloy MH ₂ at low pressure, and release hydrogen H ₂ from the hydrogen storage alloy MH ₂ at high temperature and high pressure. Use hydrogen H ₂ instead of air in the air compressor. can do.

Further, FIG. 9 shows an application example to a chemical engine. As shown, the chemical engine 41 heats the hydrogen storage alloy MH ₂ with hot water to release hydrogen H ₂ and actuate the piston 42. After that, the hydrogen storage alloy MH ₂ is cooled with cold water and hydrogen H ₂ is stored therein. The unit of a plurality of hydrogen storage alloys MH ₂ is alternately cycled to interlock the operation of the piston 42.

FIG. 10 shows an example of application to a cooling / refrigerating device. As shown, cooling
The refrigerating apparatus 51 uses CaNi ₅ as the hydrogen storage alloy MH _2.
The alloy 51a and the LaNi ₅ alloy 51b are provided. At the same temperature, LaNi _{5 is} better than CaNi ₅ alloy 51a.
The release pressure of hydrogen H ₂ is higher in the alloy 51b. First, C
Only the aNi ₅ alloy 51a is heated by solar heat to obtain the LaNi ₅ alloy.
Higher release pressure of hydrogen H ₂ than alloy 51b, hydrogen H ₂ moves all towards the LaNi ₅ alloy 51b. After that, the temperature of the CaNi ₅ alloy 51a is changed to the LaNi ₅ alloy 51a.
When the temperature is lower than the temperature of b, release of hydrogen H ₂ from the LaNi ₅ alloy 51b starts. Since this is an endothermic reaction, the inside of the room is configured to be cooled through the heat exchanger 52. The heat generated when hydrogen H ₂ is transferred to and stored in the LaNi ₅ alloy 51b is discarded outdoors.

Finally, an application example to a hydrogen isotope separation device will be described. Hydrogen isotope separation is a technique for separating hydrogen and hydrogen isotopes, deuterium, and tritium by utilizing the fact that the pressures released by the host metal or alloy differ at each temperature. For example, after the mixed gas of hydrogen and deuterium is stored in the hydrogen storage alloy MH ₂ , the pressure is not released for deuterium, but if the pressure is reduced to the pressure for releasing hydrogen H ₂ , only hydrogen is separated as a gas. However, deuterium remains in the hydrogen storage alloy MH ₂ .

If the hydrogen storage alloys MH ₂ in the above-mentioned various devices are hydrogen storage alloys 1 and 21 in which the thermoelectric elements of the first and second embodiments are combined, the structure can be changed as appropriate. It can be expected to make the device more compact.

Next, in order to clarify the present invention, publicly known documents relating to the present invention will be cited, and differences from these will be briefly described.

First, Japanese Patent Laid-Open No. 63-246458 proposes "a method for warming up a fuel tank in an engine utilizing metal hydride". This proposal is a technique that only heats the hydrogen storage alloy MH ₂ by utilizing engine exhaust heat, and does not touch on the problem at the time of engine start, which is solved by the present invention.

Further, Japanese Patent Application Laid-Open No. 62-113859 proposes "a preheating device for a hydrogen vehicle". Even in this proposal, the problem of starting the engine is not mentioned.

Further, Japanese Patent Application Laid-Open No. 63-36659 proposes an "automotive fuel system cooling device". This proposal is a technique for cooling a general fuel such as gasoline by using a thermoelectric element in order to prevent evaporation (gasification), and heats or cools the hydrogen storage alloy MH ₂ as in the present invention. Therefore, it is different from the technique of controlling the storage / release of hydrogen H _{2 in} the purpose and the effect.

In Japanese Patent Laid-Open No. 63-111269, there is proposed an "engine exhaust heat utilization device".
In this proposal, a thermoelectric element is used to heat the combustion chamber (Peltier effect), and waste heat is used to generate electricity (Seebeck effect).
On the other hand, in the present invention, the use of exhaust heat is secondary, and one thermoelectric element 4 performs heating and cooling by the Peltier effect. Moreover, it is a technology that starts the engine only by the Peltier effect.

As described above, the present invention has an unpredictable and superior effect over the known techniques, and is a technique having a completely different configuration from those techniques.

[0048]

As described above, according to the hydrogen storage alloy in which the thermoelectric element according to the present invention is combined, a large-scale heating / heating
It does not require a decompression device or a cooling / pressurizing device, and has the excellent effect that it is possible to consistently perform start-up / operation / hydrogen supply of various devices.

[Brief description of drawings]

FIG. 1 is a schematic view showing a first embodiment of a hydrogen storage alloy compounding a thermoelectric element according to the present invention.

FIG. 2 is an explanatory diagram showing application of a hydrogen storage alloy, which is a composite of the thermoelectric elements of the first embodiment, to a vehicle.

FIG. 3 is an explanatory diagram showing application of a hydrogen storage alloy compounding the thermoelectric elements of the first embodiment to an on-vehicle fuel cell.

FIG. 4 is an explanatory diagram showing a driving operation situation at the time of hydrogen supply.

FIG. 5 is an explanatory diagram showing a driving operation situation at the time of starting the engine.

FIG. 6 is a schematic view showing a second embodiment of the hydrogen storage alloy in which the thermoelectric element according to the present invention is combined.

FIG. 7 is an explanatory diagram showing energy conversion of hydrogen released from a hydrogen storage alloy.

FIG. 8 is a schematic diagram showing an application example to a heat storage device.

FIG. 9 is a schematic diagram showing an application example to a chemical engine.

FIG. 10 is a schematic diagram showing an application example to a cooling / refrigerating apparatus.

FIG. 11 is an explanatory diagram showing a mechanism of hydrogen storage / release of a hydrogen storage alloy.

[Explanation of symbols]

 M hydrogen storage alloy 2 insulator 4 thermoelectric element 4a p-type semiconductor 4b n-type semiconductor 6 constant voltage power supply

Claims (3)

[Claims] 1. A hydrogen storage alloy that occludes hydrogen by cooling and pressurization and releases hydrogen by heating and decompression, and insulates a thermoelectric element formed of a p-type semiconductor and an n-type semiconductor in the hydrogen storage alloy. A hydrogen storage alloy having a composite thermoelectric element, wherein the thermoelectric element is fixed through a body and a predetermined voltage is applied to the thermoelectric element. 2. The hydrogen storage alloy according to claim 1, wherein a predetermined voltage is applied to the thermoelectric element so that the forward and reverse electrodes can be freely converted. 3. The hydrogen storage alloy in which the thermoelectric element according to claim 1 is combined with a pipe for allowing a fluid to pass through the hydrogen storage alloy.