JPS63143466A - Heat pump utilizing metallic hydride and control method thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a heat pump using metal hydrides and a control method thereof.

(B) Prior Art A conventional heat pump using a metal hydride is disclosed, for example, in Japanese Patent Publication No. 19955/1983. The air-conditioning system shown in this figure consists of two air-conditioning blocks that are made up of two heat-exchangeable containers each containing two types of metal hydrides with different hydrogen equilibrium pressures, which are connected to each other.
One container in each group is heated and cooled alternately, heat is absorbed and radiated alternately in the other container in each group, and the other container is alternately used as a heating and cooling source to provide continuous cooling or heating. This is how it was done.

In the case of this heating and cooling device, the process of feeding hydrogen gas and the process of sending hydrogen gas out are alternately repeated for one container. In the first step the temperature of the metal hydride increases and in the second step the temperature decreases. Incidentally, in another container, the same process as above is repeated with the phase shifted.

(c) Problems to be solved by the invention In such conventional heat pumps using metal hydrides, immediately after reversing the heating and cooling of one container to reverse the flow direction of hydrogen gas, Since the container on the high temperature side is cooled and the container on the low temperature side is heated, there is a problem that heat loss is extremely large. Further, immediately after the heating/cooling is reversed, a high temperature heat medium is temporarily supplied during cooling, for example, and smooth continuous heating and cooling cannot be performed. The present invention aims to solve these problems.

(d) Means for Solving the Problems The present invention uses five sets of heat exchangers for metal hydrides to store heat remaining in the heat exchangers for metal hydrides after the completion of the hydrogen storage reaction. The above problems are solved by using the heat exchanger for other metal hydrides during the reaction. That is, the heat pump using metal hydride according to the present invention includes three sets of metal hydride heat exchangers (11, 12, and 13) for the first heat medium and two trillion metal hydride heat exchangers for the second heat medium. Hydrogen gas passage switching device (41, 42, 43, 44) capable of switching the movement state of hydrogen gas between the hydride heat exchangers (114 and 115) and the five sets of metal hydride heat exchangers
, 45, 46, 147, 148, 149 and 150) and the heat medium passages of the three sets of metal hydride heat exchangers (
21, 22, and 23), a low temperature side heat exchange unit for the first heat medium (15), and a high temperature side heat exchange unit for the first heat medium (15).
16) first heat medium passage switching device (51, 52, 53) that switches the connection state with the heat medium passage (25 and 26).
,54,55,56,57,58,59,60,61,
62, 63, 64, and 65), first heat medium pumps (17 and 18) that circulate the first heat medium through the first heat medium path switching device, and the two sets of metal hydride heat exchangers. The heat medium passages (124 and 125) of the second heat medium low temperature side heat exchange unit (130) and the heat medium passage (132) of the second heat medium high temperature side heat exchange unit (134)
and 136) for switching the connection state with the second heat medium passage switching device (151, 152, 153, 154, 155).
, 156, 157, and 158), and second heat medium pumps (170 and 172) that circulate the second heat medium through the second heat medium path switching device. Note that the symbols in parentheses indicate corresponding members in the embodiments described later.

Further, the method for controlling a heat pump using a metal hydride according to the present invention includes controlling the second heat medium passage switching device and the hydrogen gas passage switching device, thereby controlling the third metal hydride heat exchanger (13). The hydrogen gas is transferred from the other of the fourth and fifth metal hydride heat exchangers (114 and 115), and the first metal hydride heat is transferred from the other of the fourth and lower metal hydride heat exchangers (114 and 115). Exchanger (11
), the movement of hydrogen from the second metal hydride heat exchanger (12) is stopped, and the 71g1 heat medium passage switching device is used to transfer the hydrogen gas from the second metal hydride heat exchanger to the first metal hydride heat exchanger (12). A first heat medium passage is formed in which the first heat medium circulates in the order of hydride heat exchanger → first heat medium high temperature side heat exchange unit → second metal hydride heat exchanger, and A first step of forming a first heat medium passage through which the first heat medium circulates in the order of the three-metal hydride heat exchanger → the first heat medium low-temperature side heat exchange unit → the third metal hydride heat exchanger. , by controlling the second heat medium passage switching device and the hydrogen gas passage switching device, hydrogen is transferred from the second metal hydride heat exchanger to either the fourth or fifth metal hydride heat exchanger. The hydrogen gas is transferred from the other of the fourth and fifth metal hydride heat exchangers to the third metal hydride heat exchanger, and the hydrogen in the first metal hydride heat exchanger is transferred. and by the first heat medium path switching device,
The first heat medium circulates in the order of the first heat exchanger for metal hydride → the third heat exchanger for metal hydride → the high temperature side heat exchange unit for the first heat medium → the first heat exchanger for metal hydride. 1 form a heat medium passage, and a 2nd metal hydride heat exchanger→
A second step of forming a first heat medium passage in which the first heat medium circulates in the order of the first heat medium low-temperature side heat exchange unit → the second metal hydride heat exchanger, and the second heat medium passage switching device and the hydrogen gas passage switching device.
Transferring hydrogen gas from the metal hydride heat exchanger to one of the fourth and fifth metal hydride heat exchangers, and from the other of the fourth and fifth metal hydride heat exchangers to the second metal hydride heat exchanger.
The hydrogen gas is transferred to the heat exchanger for metal hydride, the transfer of hydrogen in the heat exchanger for third metal hydride is stopped, and the first heat exchanger for heat medium is transferred to the heat exchanger for third metal hydride. → second metal hydride heat exchanger → first heat medium high temperature side heat exchange unit → third metal hydride heat exchanger to form a first heat medium passage through which the first heat medium circulates. In addition, a first heat medium passage is formed in which the first heat medium circulates in the order of the first metal hydride heat exchanger → the first heat medium low-temperature side heat exchange unit → the first metal hydride heat exchanger. The gist is to sequentially repeat the above-mentioned 1st to 3rd steps of 'fJ3 step.

(e) Effect Regarding the heat exchanger for the first metal hydride, the temperature rises in the first step, and then in the second step, the temperature rises in the heat exchanger for the third metal hydride. Heat is extracted from the first metal hydride heat exchanger due to the flow of the heat medium. In the third step, heat absorption begins and the temperature of the first metal hydride heat exchanger rapidly decreases. As described above, in the second step, the heat possessed by the first metal hydride heat exchanger is absorbed, increasing the amount of heat acquired. While the heat exchanger for the first metal hydride is absorbing heat in the second step, heat is generated in the heat exchanger for the third metal hydride, so the temperature increase characteristics do not deteriorate. . This kind of effect also occurs in the other two metal hydride heat exchangers.
The phase is shifted by /3. Thereby, the amount of heat acquired can be increased without deteriorating the temperature increase characteristics.

(F) Embodiment FIG. 1 shows an embodiment of the present invention. First metal hydride heat exchanger for first heat medium 11. A second metal hydride heat exchanger 12, a third metal hydride heat exchanger 13, and a second metal hydride heat exchanger 12 and a third metal hydride heat exchanger 13;
Fourth metal hydride heat exchanger 114 and fifth heat exchanger for heat medium
The metal hydride heat exchanger 115 includes valves 41, 42, 43, 44, 45, 46 which are hydrogen gas passage switching devices.
．． 147, 148, 149 and 150 as shown in FIG. 1, and valves 41.42.43.
44.45.46.147.148.149 and 150
Metal hydride heat exchanger 1 by controlling the opening and closing of
1.12.13.Hydrogen gas can be moved between 114 and 115. Heat exchanger for metal hydrides 11.12.
13, 114 and 115 are filled with metal hydride. Heat exchangers for metal hydrides 11, 12 and 13
Each of the heat medium passages 21, 22 and 23 in The heat medium passage 25 of the first heat medium high temperature side heat exchange unit 16 (for example, the indoor heat exchange unit when used as a heating device, or the indoor heat exchange unit when used as a refrigeration device) is connected to the heat medium passage 26 of the heat source side heat exchange unit (heat source side heat exchange unit) as shown in FIG. In addition, in the middle of the piping, valves 51, 52, 53, 54, 55, 56, 57, 58, 5, which are first heat medium passage switching devices, are installed as shown in the figure.
9.60.61.62.63.64 and 65, and the first
Heat medium pumps 17 and 18 are provided. The heat medium passages 124 and 125 in the metal hydride heat exchangers 114 and 115 are respectively the heat medium passage 132 of the second heat medium low temperature side heat exchange unit 30 and the second heat medium high temperature side heat exchange unit 30. It is connected to the heat medium passage 136 of the exchange unit 134 as shown in FIG.

In addition, as shown in the figure, valves 151, 152, 153, 154, .
155, 156, 157 and 158, and second heat medium pumps 170 and 172 are provided. valve 41
．． 42.43.44.45.46.147.148.1
Opening and closing of 49 and 150, valves 51, 52, 53, 54
, 55, 56, 57, 58, 59.60.61.62.
Opening and closing of 63.64 and 65, and valves 151.152
．． 153.154.155.156.157 and 158
The opening and closing are performed by commands from a control device (not shown).

Next, the operation of this embodiment will be explained.

First, in the first step, the valve 45 and the valve 150 are opened so as to send hydrogen gas from the third metal hydride heat exchanger 13 to the fifth metal hydride heat exchanger 115, and the fourth metal hydride heat exchanger 115 is opened. The valve 4 is configured to move hydrogen gas from the heat exchanger 114 to the first metal hydride heat exchanger 11.
2 and valve 147 are opened, and the other valves 41.4
3.44.46.148 and 149 are closed.

Also, valves 60.56.53.64 and 62 are opened and valves 51.52.54.55.57.58.59.6
1.63 and 65 are closed. Additionally, valve 156.1
58.151 and 153 open, valve 155.15
7. Leave 152 and 154 blank. The flow of hydrogen gas and heat medium in this state is shown in FIG. 2 by extracting only the necessary portions. The heat medium is transferred from the first heat medium high temperature side heat exchange unit 16 → second metal hydride heat exchanger 12 → first metal hydride heat exchanger 11 → first heat medium high temperature side heat exchange unit 16. It will be cycled in order. Further, the heat medium flows between the first heat medium low temperature side heat exchange unit 15 and the third metal hydride heat exchanger 13. Furthermore,
Between the fifth metal hydride heat exchanger 115 and the second heat medium low temperature side heat exchange unit 130, and between the fourth metal hydride heat exchanger 114 and the second heat medium high temperature side heat exchange unit 134. A second heat medium flows between the two. In this state, hydrogen gas is released in the third metal hydride heat exchanger 13, and heat is taken away from the first heat medium in the heat medium passage 23. As a result, the first heat medium whose temperature has decreased is supplied to the heat medium passage 25. Further, hydrogen gas is stored in the first metal hydride heat exchanger 11, and the heat medium passage 2
Heat is released to 1. As a result, the heated first heat medium is supplied to the heat medium passage 26. That is, heat is absorbed in the first heat medium low temperature side heat exchange unit 15, and the first
Heat is released in the high temperature side heat exchange unit 16 for heat medium.

When the hydrogen gas pressure in the first metal hydride heat exchanger 11 reaches a predetermined value (or when a predetermined time has elapsed), the first step is switched to the first intermediate step.

i.e. valve 151.152.153.154.1
55.156.157 and 158 are closed and valve 41.42.43.44.45.46.147.14
8.149 and 150 are closed. However, valve 6
0.56.53.64 and 62 open state and valve 51
．． The closed states of 52, 54, 55, 57, 58, 59, 61, 63 and 65 are maintained as in the first step. This state is shown in FIG. Immediately after the first intermediate step is started, the metal hydride in the third metal hydride heat exchanger 13 is in a low temperature state, and the metal hydride in the first metal hydride heat exchanger 11 is in a high temperature state. . Heat is absorbed by the first heat medium flowing through the heat medium passage 21 of the first metal hydride heat exchanger 11, and ? The temperature of the metal hydride in the J1 metal hydride heat exchanger 11 gradually decreases.

After a predetermined period of time has passed in this state, the second step is started.

In the second step, valves 43.148.149 and 46 are opened, and valves 41.42.44.45.147 and 15 are opened.
0 is considered closed. Also, valve 155.157.152
and 154 are opened, and valves 151.153.156
and 158 are closed. At the same time valve 55.51.6
3.59° and 57 are open, valve 52.53.5
4.56.58.60.61.62%64 and 65 are closed. This state is shown in FIG. Hydrogen is transferred from the metal hydride heat exchanger 12 to the fourth metal hydride heat exchanger 11
4, and 'fp15 metal hydride heat exchanger 1
15 to the third metal hydride heat exchanger 13, heat is absorbed in the metal hydride heat exchanger 12, and heat is generated in the third metal hydride heat exchanger 13. The first heat medium is the first heat medium high temperature side heat exchange unit 16 → the first metal hydride heat exchanger 11 → the third metal hydride heat exchanger 13
→It circulates in the order of the high temperature side heat exchange unit 16 for the first heat medium. Further, a first
The heat medium will flow. Hydrogen is not transferred in the first heat exchanger 11 for metal hydride, but the heat held up to the second step is transferred to the first heat medium before entering the third heat exchanger 13 for metal hydride. Absorbed. The first heat medium is further heated in the third metal hydride heat exchanger 13 .

When a predetermined period of time has elapsed in this state of the second step, the second intermediate step begins.

In the second intermediate process, valve 41.42.43.44.45
and 46 are closed, and valves 151.152.1
53.154.155.156.157 and 158 are closed. However, valves 55.51.63.59 and 57 remain open, and valves 52.53.54.56
．． 58, 60, 61, 62, 64 and 65 remain closed, and the first heat medium passage is maintained in the same state as in the second step. In this state, the temperature of the metal hydride in the third metal hydride heat exchanger 13 gradually decreases, and the temperature of the metal hydride in the second metal hydride heat exchanger 12 gradually increases. During this time as well, the amount of heat remaining in the first metal hydride heat exchanger 11 is absorbed by the first heat medium flowing through the heat medium passage 21 of the first metal hydride heat exchanger 11 . When a predetermined period of time has elapsed, the second intermediate step is switched to the third step.

In the third step, valve 41.150. ．． 147 and valve 44 are opened, and valve 42.43.45.46.14
8 and 149 are set as rl. Valve 156.158.
151 and 153 are open, and valves 152, 154.
155 and 157 are closed. At the same time, valves 65.61.58.54 and 52 are opened, and valves 51.53.55.56.57.59.60.62.
63 and 64 are closed. This state is shown in FIG.

Hydrogen moves from the first metal hydride heat exchanger 11 to the fifth metal hydride heat exchanger 115 and from the fourth metal hydride heat exchanger 114 to the second metal hydride heat exchanger 1.
2, heat is absorbed in the first metal hydride heat exchanger 12, and heat is generated in the second metal hydride heat exchanger 12.

The first heat medium is the first heat medium high temperature side heat exchange unit 16→
Third metal hydride heat exchanger 13 → second metal hydride heat exchanger 12 → first heat medium high temperature side heat exchange unit 16
cycle in this order. Also, the first metal hydride heat exchanger 11
and the first heat medium low temperature side heat exchange unit 15.
The heat medium circulates. The first heat medium that has absorbed the heat remaining in the third metal hydride heat exchanger 13 enters the second metal hydride heat exchanger 12 and is further heated. Then, after a predetermined period of time has elapsed, the process switches to the third intermediate step.

In the third intermediate process, valve 41.42.43.44.45
．． 46.147.148.149 and 150 are closed. Also, valve 151.152.153.154.1
55.156.157 and 158 are closed. However, valves 65.61.58.54 and 52 remain open, and valve 51.53.55.56.57.5 remains open.
9.60.62.63 and 64 were left empty and the third
The same state as the process is maintained. This state is shown in FIG. Even in this state, the first heat medium enters the second metal hydride heat exchanger 12 after absorbing the residual heat of the third metal hydride heat exchanger 13 . When a predetermined time has elapsed in this third intermediate step, the process returns to the first step and the same operation is repeated. However, three metal hydride heat exchangers 11.1
2 and 13 and the two metal hydride heat exchangers 114 and 115 in a predetermined combination, the combination is the same every two cycles, and the steps are the same in adjacent cycles. However, the combinations of metal hydride heat exchangers that exchange hydrogen gas with each other are not the same.

Heat exchanger 11.1 for each metal hydride in each of the above steps
The temperature of the first heat medium at the outlets 2 and 13 is shown in FIG. For example, the temperature change of the first metal hydride heat exchanger 11 is as follows.

First, in the first step, hydrogen is fed, and the temperature rises due to the hydrogen absorption reaction, reaching the 84 point from the ao point. Then, when the first intermediate step begins, the hydrogen storage reaction slows down or stops, and the temperature gradually decreases to a temperature of 82 points. Then, during the second step and the second intermediate step, the temperature further decreases (a2→a3→a4) and becomes approximately equal to the population temperature of the high temperature side heat medium. When the third step begins, the temperature further decreases to 35 points due to the hydrogen release reaction. Then the third
When the intermediate step is started, the hydrogen release reaction slows down or stops, and the temperature gradually increases to the temperature of 86 points.

Regarding the first metal hydride heat exchanger 11, the above temperature changes are repeated. Heat exchanger 1 for second metal hydride
The second and third metal hydride heat exchangers 13 show similar changes with a phase shift of 1/3. Due to the above operation, for example, the high temperature side heat medium enters the heat exchanger 11 for the first metal hydride, which was at a high temperature in the first intermediate step, in the 'ffJ2 step and the second intermediate step, and Since the heat remaining in the heat exchanger 11 is recovered and then enters the third metal hydride heat exchanger 13, the first metal hydride heat exchanger 11 is recovered without lowering the high temperature side heat medium population temperature.
The remaining heat can be recovered. That is,
The amount of heat acquired can be increased without reducing the temperature increase characteristics.

In the described embodiment, the first intermediate step, the second intermediate step, and the second intermediate step are performed after the first step, second step, and third step, respectively.
Although a third intermediate step and a third intermediate step are provided, the same effect can be obtained even if these steps are omitted and the steps are repeated in the order of the first step → second step → third step → first step. However, it is more advantageous to provide an intermediate step in terms of the efficiency of the amount of heat obtained. In addition, although the terms "first heat medium" and "second heat medium" are used to indicate that the systems of the heat medium are different, these are the same thing,
It goes without saying that water may be used, for example.

(G) As described in detail, according to the present invention, one set of metal hydride heat exchangers is operated while two sets of metal hydride heat exchangers are respectively discharging and absorbing heat. Since the heat remaining in the vessel is recovered, the amount of heat acquired can be increased without reducing the temperature raising ability, and thermal efficiency is significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a heat pump according to the present invention, Fig. 2 is a diagram showing the 7jfJ1 process of the heat pump, Fig. 3 is a diagram showing the first intermediate process of the heat pump, and Fig. 4 is a diagram showing the second process of the beat pump. Figure 5 is a diagram showing the second intermediate process of the heat pump, Figure 6 is a diagram showing the third intermediate process of the heat pump, Figure 7 is a diagram showing the third intermediate process of the heat pump,
FIG. 8 is a diagram showing temperature changes in the metal hydride heat exchanger according to the present invention. 11... Heat exchanger for first metal hydride, 12... Heat exchanger for second metal hydride, 13... Heat exchanger for fJ3 metal hydride, 114... Fourth metal hydrogen Heat exchanger for compounds, 115... Heat exchanger for fifth metal hydrides, 1
5...low temperature side heat exchange unit for first heat medium, 16...
- High temperature side heat exchange unit for the first heat medium, 130... Low temperature side heat exchange unit for the second heat medium, 134... High temperature side heat exchange unit for the second heat medium, 21, 22, 23...
Heat medium passage, 25.26 Heat medium passage, 132
, 136... Heat medium passage, 41.42, 43, 44
,45,46,147°148.149,150...
Valve, 51° 52.53, 54, 55, 56, 57,
58゜59.60, 61, 62, 63, 64.65...
・Valve, 151, 152, 153, 154° 155.
156,157,158...Valve, 17.18...
- First heat medium pump, 170°172... second heat medium pump.

Claims (1)

[Claims] 1. Three sets of metal hydride heat exchangers for a first heat medium;
two sets of metal hydride heat exchangers for the second heat medium; a hydrogen gas path switching device capable of switching the movement state of hydrogen gas between the five sets of metal hydride heat exchangers; and the three sets described above. A first heat medium that switches the connection state between the heat medium passage of the metal hydride heat exchanger and the heat medium passage of the first heat medium low temperature side heat exchange unit and the first heat medium high temperature side heat exchange unit. through the first heat transfer path switching device and the first heat transfer path switching device.
A first heat medium pump that circulates a heat medium, heat medium passages of the two metal hydride heat exchangers, a second heat medium low temperature side heat exchange unit, and a second heat medium high temperature side heat exchange unit. Metal hydrogen having a second heat medium passage switching device that switches the connection state with the heat medium passage of the unit, and a second heat medium pump that circulates the second heat medium through the second heat medium passage switching device. A heat pump that uses chemical substances. 2. first, second and third metal hydride heat exchangers for the first heat medium; fourth and fifth metal hydride heat exchangers for the second heat medium; a hydrogen gas passage switching device capable of switching the movement state of hydrogen gas between the second, third, fourth, and fifth metal hydride heat exchangers; and the first, second, and third metal hydride heat exchangers. first heat medium passage switching for switching the connection state between the heat medium passage of the chemical heat exchanger and the heat medium passages of the first heat medium low temperature side heat exchange unit and the first heat medium high temperature side heat exchange unit; a first heat medium pump that circulates the first heat medium through the first heat medium passage switching device; a heat medium passage and a second heat medium of the fourth and fifth metal hydride heat exchangers; A second heat medium passage switching device that switches the connection state of the medium low temperature side heat exchange unit and the second heat medium high temperature side heat exchange unit with the heat medium passage; In the method for controlling a heat pump using a metal hydride, the method includes: a second heat medium pump for circulating a heat medium; The hydrogen gas is transferred from the metal hydride heat exchanger to one of the fourth and fifth metal hydride heat exchangers, and the first metal hydrogen is transferred from the other of the fourth and fifth metal hydride heat exchangers. Transfer hydrogen gas to a chemical heat exchanger,
Hydrogen transfer in the second metal hydride heat exchanger is stopped;
The first heat medium passage switching device causes the second metal hydride heat exchanger→first metal hydride heat exchanger→first heat medium high temperature side heat exchange unit→second metal hydride heat exchanger A first heat medium passage is formed in which the first heat medium circulates in this order, and the third metal hydride heat exchanger → the first heat medium low-temperature side heat exchange unit → the third metal hydride heat exchanger A first heat medium path forming a first heat medium passage through which the first heat medium circulates in the order of
Step, by controlling the second heat medium passage switching device and the hydrogen gas passage switching device, from the second metal hydride heat exchanger to either the fourth or fifth metal hydride heat exchanger. Transferring hydrogen gas and transferring hydrogen gas from the other of the fourth and fifth metal hydride heat exchangers to the third metal hydride heat exchanger, and transferring hydrogen from the first metal hydride heat exchanger. is stopped, and the first heat medium passage switching device switches the first metal hydride heat exchanger → the third metal hydride heat exchanger → the first heat medium high-temperature side heat exchange unit → the first
A first heat medium passage is formed in which the first heat medium circulates in the order of the metal hydride heat exchanger, and the second metal hydride heat exchanger → the first heat medium low-temperature side heat exchange unit → the second A second step of forming a first heat medium passage through which the first heat medium circulates in the order of the metal hydride heat exchanger, by controlling the second heat medium passage switching device and the hydrogen gas passage switching device, Hydrogen gas is transferred from the first metal hydride heat exchanger to one of the fourth and fifth metal hydride heat exchangers, and from the other of the fourth and fifth metal hydride heat exchangers to the second metal hydride heat exchanger. The hydrogen gas is transferred to the metal hydride heat exchanger, the hydrogen transfer to the third metal hydride heat exchanger is stopped, and the first heat medium passage switching device is used to transfer the hydrogen gas to the third metal hydride heat exchanger→ The first heat medium circulates in the order of the second heat exchanger for metal hydride → the high temperature side heat exchange unit for the first heat medium → the third heat exchanger for metal hydride.
A first heat medium that forms a heat medium passage, and in which the first heat medium circulates in the order of the first metal hydride heat exchanger → the first heat medium low-temperature side heat exchange unit → the first metal hydride heat exchanger. A method for controlling a heat pump using a metal hydride, characterized by sequentially repeating the above first to third steps, a third step of forming a heat medium passage. 3. Between each of the first, second, and third steps, stop the movement of hydrogen gas between each metal hydride heat exchanger, and stop the movement of hydrogen gas between the first heat medium passages in the previous step. A method for controlling a heat pump using a metal hydride according to claim 2, further comprising an intermediate step of holding the metal hydride as it is.