JPH0472141B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a heat transfer device using a metal hydride.

[Background of the invention]

It is known that conventional metals or alloys react with hydrogen to form hydrides while generating heat, and conversely, they separate hydrogen by heating this hydride. There is a device that uses two types of such metal hydrides to transfer heat. An example thereof will be briefly described with reference to FIGS. 1 and 2.

FIG. 1 shows the relationship between hydrogen equilibrium pressure and temperature, with the vertical axis representing the logarithm of the hydrogen equilibrium pressure and the horizontal axis representing the reciprocal of absolute temperature. The metal hydride with higher equilibrium hydrogen pressure at the same temperature is indicated by M _A , and the metal hydride with lower equilibrium pressure is indicated by M _B . In Figure 2, 1 is the metal hydride with higher hydrogen equilibrium pressure, 2 is the metal hydride with lower hydrogen equilibrium pressure, 1
a and 2a are containers containing the respective metal hydrides; 1b and 2b are heat exchangers for heat of reaction when the metal hydride combines with hydrogen or decomposes with a heat medium outside the containers 1a and 2a; The exchanger 3 is a hydrogen conduction path for allowing hydrogen to move between the containers 1a and 2a, and 4 is a heating device for heating the metal hydride 2 having a lower hydrogen equilibrium pressure. .

The operation of this conventional example will be described first from the point in time when hydrogen is decomposed from the metal hydride 2. For example, the metal hydride 2 is heated with a heating device 4 such as an electric heater. Then, the temperature of the metal hydride 2 increases, and the hydrogen equilibrium pressure also increases accordingly. Then, when the hydrogen equilibrium pressure becomes higher than the hydrogen equilibrium pressure at the temperature T _MA of the metal hydride 1, the metal hydride 2 separates hydrogen while absorbing heat _QHB from the heating device 4. The separated hydrogen flows through the hydrogen conduit 3 as shown in FIG. 2, flows into the container 1a, and reacts with the metal hydride 1 while generating reaction heat. The heat generated at this time
Q _MA is transported to the place of use using a medium-temperature heat medium and used.
At the end of this process, the hydrogen concentration in metal hydride 2 is low and the hydrogen concentration in metal hydride 1 is high.

Next, a low-temperature heat medium is passed around the heat exchanger 1b for the metal hydride 1, and a medium-temperature heat medium is passed around the heat exchanger 2b for the metal hydride 2. Then, the hydrogen equilibrium pressure of metal hydride 1 at temperature T _LA becomes higher than the hydrogen equilibrium pressure of metal hydride 2 at temperature T _MB . Then, metal hydride 1 absorbs heat Q _LA from the low-temperature heat medium and generates hydrogen as shown in Fig. 2, and the hydrogen reacts with metal hydride 2 to generate heat Q _MB.
React while generating. When this process is completed, the hydrogen concentration of metal hydride 1 becomes low, and the hydrogen concentration of metal hydride 2 becomes high. Then, the cycle of heating the metal hydride 2 with the heating device 4 is repeated again as described above.

By doing this, metal hydride 1,
2 itself, or containers 1a, 2a, heat exchanger 1
If you ignore various losses due to heat capacity and other factors such as b, 2b, etc., the temperature level of T _HB (for example, about 100℃)
With the heat Q _HB , the heat Q _LA can be pumped up from a poor quality heat source (e.g. outside air at around 10°C) at a low temperature T _LA and the effectively usable temperature level T _MA , T _MB (e.g. 40 to 50 ℃), it is possible to obtain approximately twice the heat (Q _MA + Q _MB ) as the heat Q _HB produced by heating at a high temperature.

However, such conventional devices still have the following inadequacies.

(1) Compared to the heat Q _HB heated at high temperature, the heat Q _MA + Q _MB available at medium temperature is about twice as much even in an ideal case ignoring various losses, and this is the heat output of a vapor compression heat pump. This is less and less efficient than compression work.

(2) Heat from inexpensive or free low-temperature heat sources cannot be used continuously. If a continuous operation is forced, two pairs of devices as shown in FIG. 2 will be required, and two sets of heating devices will be required, resulting in high costs.

[Purpose of the invention]

SUMMARY OF THE INVENTION The object of the present invention is to eliminate the aforementioned drawbacks and provide a highly efficient and low cost heat transfer device.

[Summary of the invention]

The present invention basically has the following configuration.

(1) Use four or more types of metal hydrides.

(2) Store each in a container.

(3) Connect the containers from the container containing the metal hydride with the highest hydrogen equilibrium pressure to the container containing the metal hydride with the lowest hydrogen equilibrium pressure in order of increasing hydrogen equilibrium pressure using a hydrogen conduction path.

(4) Similarly, the container containing the metal hydride with the lowest hydrogen equilibrium pressure and the container containing the highest hydrogen equilibrium pressure are connected via a hydrogen conduction path.

(5) A hydrogen control valve will be installed in these hydrogen channels to allow or block the flow of hydrogen.

(6) These containers are equipped with a heat exchanger to exchange heat of reaction when the metal hydride combines with or dissociates from hydrogen with a heat medium.

(7) Provide a high-temperature heating device to heat the metal hydride with the lowest hydrogen equilibrium pressure.

With the above configuration, by opening every other hydrogen control valve and closing the rest, two adjacent containers in the order of hydrogen equilibrium pressure are brought into communication.
The reaction of hydrogen bonding or dissociation progresses. and,
When the reaction is complete, close the hydrogen control valve that was open and open the valve that was closed. Then, the containers are shifted by one, and two adjacent containers are brought into communication, and the hydrogen reacts again. As a result, hydrogen gradually moves toward the container containing the metal hydride, which has a lower hydrogen equilibrium pressure. The hydrogen bonded to the lowest metal hydride is then heated by a high-temperature heating device, becomes high pressure, and transfers again to the metal hydride having the highest hydrogen equilibrium pressure.

[Embodiments of the invention]

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 3 to 10 for a case where floor heating is performed using underground water.

FIG. 3 is a hydrogen equilibrium pressure-temperature diagram of this example. Letting M _A , M _B , M _C , and M _D in order from the highest hydrogen equilibrium pressure to the lowest hydrogen equilibrium pressure, for example, MmNi ₅ (Mm: Mitsushi Metal), FeTi,
There are combinations of Ti _0.5 , Zr _0.4 , Mn _1.9 , LaCo ₅ , etc.
These hydrogen equilibrium pressures differ somewhat due to hysteresis when hydrogen bonds and when hydrogen dissociates, but to avoid complication, they are unified and shown as a single line for each.

T _MA , T _MB , T _MC , and _MD are the temperatures of the respective metal hydrides when hydrogen bonds, and may be the same temperature or may be slightly different.
T _LA , T _LB , T _LC are heated by low temperature heat medium,
This is the temperature at which each metal hydride dissociates hydrogen, and these may be the same or slightly different. T _HD is the temperature at which the metal hydride with the lowest hydrogen equilibrium pressure is heated by a high temperature heating device (Figure 4) to dissociate hydrogen.

In Figures 4 to 7, 5 is the metal hydride with the highest hydrogen equilibrium pressure, 6 is the next highest metal hydride, 7 is the next highest metal hydride after 6, 8 is the lowest metal hydride, 5a , 6a, 7a, and 8a are containers containing the metal hydrides 5, 6, 7, and 8, respectively, and 5b, 6b, 7b, and 8b are the respective metal hydrides and heat carriers outside the containers 5a, 6a, 7a, and 8a. 9 is a heat exchange device for exchanging heat between the metal hydrides 5 and 7 and the heat medium; 10 is a heat exchanger for exchanging heat between the metal hydrides 6 and 8 and the heat medium; The devices 11 and 12 are heat medium switching valves for transferring a low temperature heat medium and a medium temperature heat medium to the heat exchange devices 9 and 10;
14 is a low temperature heat medium pump for sending the low temperature heat medium to the heat exchange devices 9 and 10; 15 is a bed heat exchanger for utilizing the heat of the heated medium temperature heat medium. , 16 is a well for obtaining groundwater, which is a low-temperature heat medium, 17 is a discharge channel for disposing of used groundwater, and 18 is, for example, an electric heater for heating the metal hydride compound 8 having the lowest hydrogen equilibrium pressure. High temperature heating equipment such as 19, 20, 2
Reference numerals 1 and 22 are hydrogen conduction passages for allowing hydrogen to move between containers 8 and 5, 5 and 6, 6 and 7, and 7 and 8, respectively, and 23, 24, 25, and 26 are hydrogen conduction passages, respectively. The hydrogen control valves installed at 19, 20, 21, and 22 are shown. In order to avoid complication, in FIG.
4, 26, hydrogen conduction paths 19, 2 in FIG.
1 and the hydrogen control valves 23 and 25 are omitted. The connection relationship of these hydrogen conduction paths is shown in FIGS. 5 and 7.

Next, the operation of this device will be described. First, the process of transferring hydrogen from metal hydrides 8 and 6 to 5 and 7, respectively, will be explained.

The heat medium switching valves 11 and 12 are switched as shown in FIG. 4 so that the low temperature heat medium pumped up from the well 16 by the low temperature heat medium pump 14 passes through the heat exchange device 10 and is disposed of into the discharge channel 17. . Then, the hydrogen control valves 24 and 26 are closed, and the hydrogen control valves 23 and 25 are opened, and the metal hydride 8 is heated by the heating device 18, and the metal hydride 6 is heated by the low-temperature heat medium through the heat exchanger 6b. Then, metallic hydrogen 8 and 6 decompose hydrogen at temperatures T _HD and T _LB , respectively. The generated hydrogen gas passes through the hydrogen conduction paths 19 and 21, combines with the metal hydrides 5 and 7, and generates reaction heat. The generated reaction heat heats the medium temperature heat medium being circulated by the medium temperature heat medium pump 13 via the heat exchangers 5b and 7b, and is radiated and effectively used in the bed heat exchanger 15. . If this process continues for a while, the hydrogen concentration of the metal hydrides 8, 6 decreases, and the ability to generate hydrogen disappears, and conversely, the hydrogen concentration of the metal hydrides 5, 7 increases, and the ability to react with hydrogen decreases.

When this stage is reached, the heat medium switching valves 11 and 12 are switched in the opposite direction from that shown in Fig. 4, and as shown in Fig. 6,
As shown in FIG. 7, the hydrogen control valves 23 and 25, which have been open until now, are closed and 24 and 26 are opened. Then, the metal hydrides 5 and 7 heated by the low-temperature heat medium via the heat exchangers 5b and 7b decompose hydrogen at temperatures T _LA and T _LC , respectively. The generated hydrogen passes through the hydrogen conduction paths 20 and 22, combines with the metal hydrides 6 and 8, and generates reaction heat. The generated reaction heat is effectively used by heating the intermediate temperature heat medium and dissipating the heat in the bed heat exchanger 15.

According to the embodiment of the present invention described above, as is clear from FIG. 3, when various losses are ignored,
Approximately four times the amount of heat heated by the high-temperature heating device 18 can be obtained, and the efficiency can be significantly improved to approximately twice that of the conventional method. Furthermore, since the low-temperature heat medium can be used almost continuously, operating costs for heat output can also be reduced. Furthermore, since a high temperature heating device with the same heating capacity can provide about twice the heat output as a conventional device, the cost of the device can also be reduced.

In addition, by using four or more even-numbered metal hydrides, every other metal hydride can be combined in the same heat exchange device in order of hydrogen equilibrium pressure.
Even if the number of types of metal hydrides increases, the overall system requires only two heat exchangers 9 and 10, which is advantageous in terms of heat medium control and cost.

In order to increase the efficiency of the high temperature heating device 18 in the heat transfer device shown in FIGS. 4 and 6, the metal with the lowest hydrogen equilibrium pressure is provided with the high temperature heating device 18 as shown in FIGS. 8 and 9. By providing the heat exchanger 8b for the hydride 8 with a partition wall 27 and a valve 28,
While heating with the high temperature heating device 18, it is possible to improve the heat exchanger 8b to prevent heat exchange with the low temperature heat medium as much as possible. Valve 28 is the eighth
It is also possible to use a check valve with a simple structure that closes when a low-temperature heat medium is flowing as shown in the figure and opens when a medium-temperature heat medium flows as shown in FIG.

Furthermore, since metal hydrides generally have low thermal conductivity, their heat exchange performance with a heat medium tends to deteriorate. In order to improve this point, it is possible to use a heat pipe as a heat exchanger. FIG. 10 shows an embodiment using this heat pipe corresponding to FIG. 8.
In the same figure, 5c, 6c, 7c, and 8c are heat exchangers using heat pipes in which one heat exchange part is installed in a metal hydride and the other heat exchange part is installed in a heat exchange device through which a heat medium flows. It is a vessel. By doing so, the degree of freedom in arranging the heat exchangers 5c, 6c, 7c, and 8c in the heat exchangers 9 and 10 increases, and the flow resistance of the heat medium can be reduced.

In the embodiments shown in Figs. 3 to 10 above, heat transfer devices for floor heating have been described, but by lowering the operating temperature level of these embodiments and using a low-temperature heat medium as shown in Fig. 11. It can also be used as a heat transfer device that efficiently generates low temperature by circulating the heat of the medium-temperature heat medium through the cooler 29 of the refrigerator and radiating the heat into the air through the heat exchanger 30.

〔Effect of the invention〕

According to the present invention, since every other heat exchanger can be combined in the same heat exchanger in the order of hydrogen equilibrium pressure, even if the number of types of metal hydrides increases, the overall system requires only two heat exchangers 9 and 10. This is advantageous in terms of heat medium control and cost. In addition, by heating the metal hydride with the lowest hydrogen equilibrium pressure in the heat transfer device once in one cycle using the high-temperature heating device, it absorbs heat from the low-temperature heat medium three or more times and transfers it to the medium-temperature heat medium four or more times. Since heat can be radiated, heat can be transferred extremely efficiently.

Further, since heat can be continuously absorbed from the low-temperature heat medium with one high-temperature heating device, the cost of the device can be reduced.

[Brief explanation of the drawing]

Figure 1 is a hydrogen equilibrium pressure-temperature diagram of a metal hydride in a conventional apparatus, Figures 2a and b are schematic diagrams of the conventional apparatus, and Figure 3 shows the operation of an embodiment of the apparatus of the present invention. Hydrogen equilibrium pressure-temperature diagrams, FIGS. 4 to 11 are schematic diagrams showing embodiments of the apparatus of the present invention. 5,6,7,8...metal hydride, 5a,6
a, 7a, 8a...container, 5b, 6b, 7b, 8
b... Heat exchanger, 19, 20, 21, 22... Hydrogen introduction path, 23, 24, 25, 26... Hydrogen control valve.

Claims (1)

[Claims] 1 In a heat transfer device using metal hydride,
At least four or more even types of metal hydrides, containers for storing these metal hydrides, and containers containing the metal hydride with the highest hydrogen equilibrium pressure to store the metal hydride with the lowest hydrogen equilibrium pressure. A hydrogen conduction path connects two containers in order of their hydrogen equilibrium pressure to the container containing the metal hydride with the lowest hydrogen equilibrium pressure, and a metal hydride with the highest hydrogen equilibrium pressure to the container containing the metal hydride with the highest hydrogen equilibrium pressure. Hydrogen conduction paths connecting the metal hydride to the container in which the metal hydride is stored, hydrogen control valves installed in these hydrogen conduction paths, and heat exchanger for exchanging heat between the metal hydride and the low-temperature heat medium or medium-temperature heat medium outside the container. and a high-temperature heating device that heats the metal hydride with the lowest hydrogen equilibrium pressure, and every other metal hydride container with the highest hydrogen equilibrium pressure exchanges heat with a low-temperature heat medium or a medium-temperature heat medium outside the container. The metal hydride container is stored in the first heat exchanger for the purpose of heating, and every other metal hydride container with the second highest hydrogen equilibrium pressure is exchanged with a low-temperature heat medium or a medium-temperature heat medium outside the container. 1. A heat transfer device, characterized in that a second heat exchanger for storage is housed in a metal hydride container.