JP2580402B2 - Heat utilization system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is constituted by alternately supplying heat mediums having different temperature levels supplied from a plurality of heat medium supply means to a hydrogen storage alloy to cause the alloy to store and release hydrogen gas. In particular, the present invention relates to a method for supplying heat to a hydrogen storage alloy.

[0002]

2. Description of the Related Art Hydrogen storage alloys are used under certain reaction conditions.
It has the property of repeatedly storing and releasing a large amount of hydrogen, and it is known that considerable heat of reaction accompanies this storage and release. Utilizing this reaction, a heat utilization system such as a heat pump system, a heat transport system, a cold (refrigeration) system, and a hydrogen storage system have been proposed (for example,
JP-A-56-100276, JP-A-58-228
No. 54).

In the heat utilization system using such a hydrogen storage alloy, the alloy is forcibly stored and released of hydrogen in order to utilize the exothermic reaction when storing the hydrogen and the endothermic reaction when releasing the hydrogen. There is a need. for that purpose,
It is necessary to alternately supply a high-temperature heat source and a low-temperature heat source to the hydrogen storage alloy. For example, FIGS. 9 and 10 show an example of a method for supplying both heat sources. 9 and 10, 10
Reference numerals 1a and 101b denote hydrogen storage alloy tanks containing a hydrogen storage alloy MH101, and heat exchangers 102a and 102b are further stored in the tanks 101a and 101b. In the heat exchangers 102a and 102b, heat medium tubes 103
Heat medium is supplied from circulation pumps 111 and 112 through 104. Then, the heat medium pipes 103 and 10 between the circulation pumps 111 and 112 and the heat exchangers 102a and 102b.
4 is provided with switching valves 105 and 106.
The circulation pump P111 circulates the high-temperature heat medium 109 at about 130 to 150 ° C.
Circulates a low-temperature heat medium 110 of about 20 to 25 ° C.

FIG. 9 shows a state in which the high-temperature heat medium 109 is supplied to the hydrogen storage alloy tank 101a.
0 indicates a state where it is supplied to the hydrogen storage alloy tank 101b. On the other hand, FIG. 10 shows a state in which the switching valves 105 and 106 are switched to supply the low-temperature heat medium 110 to the hydrogen storage alloy tank 101a and a state in which the high-temperature heat medium 109 is supplied to the hydrogen storage alloy tank 101b. I have.

[0005]

By the way, conventionally, the switching of the valves described above is performed instantaneously, so that the temperature of the heat medium flowing into the hydrogen storage alloy tanks 101a and 101b changes rapidly. Therefore, when the above system is operated continuously for a long period of time, a rapid temperature change (thermal shock) is given to the heat medium flow passage (particularly, the heat exchangers 102a and 102b in the hydrogen storage alloy tank). Since such a thermal shock is repeatedly applied at a rate of several minutes to several tens of times, the heat exchangers 102a and 102b may be damaged,
There is a problem that the reliability of the heat utilization system is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made in consideration of the present invention. It is intended to be provided.

[0007]

According to the present invention, in order to achieve the above object, a heat storage medium having different temperature levels supplied from a plurality of heat medium supply means is alternately supplied to a hydrogen storage alloy so that the alloy can be used as an alloy. In a heat utilization system for storing and releasing hydrogen gas, a temperature measuring means for measuring a temperature of a heat medium supplied to the hydrogen storage alloy, and a heat medium when the heat medium supply is switched based on a detection result of the temperature measuring means. And a control means for controlling the heat medium supply means so that a temperature change rate of the heat medium given to the hydrogen storage alloy is equal to or less than a set value.

For example, the configuration is as follows.
The flow rate of the heat medium supplied to the hydrogen storage alloy is measured, and the circulation pump is adjusted so that the measured flow rate has a constant rate of change. In a system using two sets of two types of hydrogen storage alloys, when switching between a high-temperature heating medium for driving and a low-temperature heating medium for cooling, both are mixed so that the rate of temperature change of both heating mediums becomes a predetermined value or less. .

[0009]

With the above arrangement, based on the detection result of the calorie measuring means for measuring the calorie of the heat medium supplied to the hydrogen storage alloy, the heat medium supplied to the hydrogen storage alloy from the heat medium at the time of heat medium supply switching is switched. Since the rate of temperature change is controlled to be equal to or less than the set value, it is possible to reduce a sudden change in temperature of the heat medium flow passage (particularly, the heat exchanger in the hydrogen storage alloy tank). Thereby, the damage of the heat exchanger can be suppressed.

Furthermore, since the safety of the heat exchanger is improved, the constituent materials of the heat exchanger tubes and the like for the heat exchanger can be made thinner, so that the weight of the system can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing a heat utilization system according to an example of the present invention. This heat utilization system is a refrigeration system using two sets of two types of hydrogen storage alloys. For convenience, as shown in the drawing, a system A (II ′ system and II-I system) is used.
The system B (comprising the I 'system) and the system B (comprising the III-III' system and the IV-IV 'system) will be described separately. (Configuration of System A) In FIG. 1, reference numerals 1a and 1b denote hydrogen storage alloy tanks made of a pressure-resistant material (for example, stainless steel). The hydrogen storage alloy tanks 1a and 1b have hydrogen storage alloys MH1A and MH1B, respectively. Is housed. These hydrogen storage alloys MH1A and MH1B include rare earth-N
i system are used those AB ₅ type, the equilibrium characteristics are both represented by 7, and the hydrogen dissociation characteristics shown by the solid line b at a given temperature conditions, the dotted line b ' It has hydrogen storage properties.

Further, heat exchangers 2a and 2b are also accommodated in the hydrogen storage alloy tanks 1a and 1b, and the heat exchangers 2a and 2b are connected to the heat medium 9 via heat medium tubes 3.4. 10 are supplied. The heat exchangers 2a and 2b
In each of the heat medium tubes 3 and 4 located on the more upstream side of the heat medium flow path,
Temperature sensors 70 and 71, valves 5.6 and circulating pump 11.1
2 are provided respectively. On the other hand, heat exchangers 2a and 2b
In each of the heat medium tubes 3 and 4 located further downstream of the heat medium flow path,
Valves 7 and 8 are provided respectively. Hereinafter, of the heat medium pipes 3, the heat medium pipes up to the valve 5 are 3a, and the heat medium pipes from the valve 5 to the heat exchanger 2a.
The heat medium pipe from the heat exchanger 2a to the valve 7 is 3c, and the heat medium pipe after the valve 7 is 3d. Further, among the heat medium pipes 4, the heat medium pipe from the valve 6 to the heat exchanger 2b is 4b, the heat medium pipe from the valve 6 to the heat exchanger 2b is 4a,
The heat medium pipe up to and including the valve 8 is denoted by 4c, and the heat medium pipe after the valve 8 is denoted by 4d.

The circulating pump 11 has a temperature of 130 ° C. to 150 ° C.
Circulating the high-temperature heating medium 9 while the circulation pump 1
2 circulates a low-temperature heat medium 10 (that is, cooling water) of about 20 ° C. to 25 ° C. The branch heating medium tubes 40a, 40b, 41a, 41b are connected to the valves 5 to 8, respectively, and the valves 5 and 6 of the valves 5 to 8 are connected to the branch heating medium tubes 40a, 40a.
A flow control valve that can adjust the flow rate flowing through the heating medium pipes 40b and the heat medium pipes 3b and 4b is provided, and the valves 7.8 flow the heat medium 9 and 10 through one of the heat medium pipes 3d and 4d or the branch heat medium pipes 41a and 41b. It consists of a switching valve.

Further, the temperature sensors 70 and 71 are
Is connected to the control unit 80, and temperature signals from the temperature sensors 70 and 71 are output to the control unit 80. Further, the control unit 80 is connected to driving units (not shown) for the flow control valves 5.6 and the switching valves 7.8. Then, at the time of heat supply switching, corresponding to the temperature signal,
The openings of the flow control valves 5 and 6 are gradually adjusted. Thus, while changing the mixing ratio of the heat medium 9 and the heat medium 10 (that is, while adjusting the temperature of the heat medium sent to the hydrogen storage alloy tanks 1a and 1b), the heat medium 9 2a ・
2b. Further, at the time of heat supply switching, the switching valves 7 and 8 are ON / OFF controlled to switch the flow paths of the heat mediums 9 and 10 after the heat exchange is completed. In Figure 1 (Configuration of System B), 17a · 17b is hydrogen absorbing alloy tank made of stainless steel, the hydrogen storage alloy MH inside thereof consisting of AB ₅ type metal of the rare earth -Ni system
2C and MH2D are accommodated respectively. As shown in FIG. 7, both of the hydrogen storage alloys MH2C and MH2D have a hydrogen dissociation characteristic indicated by a solid line B and a hydrogen storage characteristic indicated by a dotted line B 'under given temperature conditions.
That is, compared to the hydrogen storage alloys MH1A and MH1B,
It has the characteristic that the equilibrium hydrogen pressure increases at the same temperature.

Heat exchangers 18a and 18b are accommodated in the hydrogen storage alloy tanks 17a and 17b, respectively.
The heat medium 27, 30 is supplied via the heat medium 27. Each of the heat medium pipes 19 and 20 located on the upstream side of the heat medium flow path from the heat exchangers 18a and 18b is provided with the switching valve 7.8.
Switching valves 21 and 22 having the same configuration as
26 are provided respectively. On the other hand, heat exchanger 18a
18b, each heat medium pipe 19
Reference numeral 20 denotes a switching valve 2 having the same configuration as the switching valves 7 and 8.
3.24 are provided. Hereinafter, the heat medium pipe 19
Among them, 19a is a heating medium pipe from the switching valve 21 to the heat exchanger 18a, 19b is a heating medium pipe from the switching valve 21 to the heat exchanger 18a, 19c is a heating medium pipe from the heat exchanger 18a to the switching valve 23, and the switching valve 23 and thereafter. Is 19d. Further, among the heat medium tubes 20, a heat medium tube from the switching valve 22 to the heat exchanger 18b is a heat medium tube 20a up to the switching valve 22;
20 heat medium tubes from the heat exchanger 18b to the switching valve 24
c, The heating medium pipe after the switching valve 24 is 20d.

The circulating pump 25 circulates a low-temperature heat medium 27 (ie, cooling water) at about 20 ° C. to 25 ° C., while a circulating pump 26 supplies a heat medium 30 for supplying cold heat to a heat load such as a freezing warehouse. Circulate. In addition, the switching valve 2
1 to 24 are branch heat medium tubes 50a, 50b, 51a, 51
b are connected respectively.

Further, the control unit 80 includes switching valves 21 to 24
(Not shown). When the heat supply is switched, the switching valves 21 to 24 are ON / OFF controlled to switch the flow paths of the heat medium 27 and 30 before and after the heat exchange. (Transmission of hydrogen between system A and system B) The hydrogen storage alloy tanks 1a and 1b and the hydrogen storage alloy tanks 17a and 17b
They are connected by hydrogen pipes 31 and 32, respectively, and allow the exchange of hydrogen between both tanks. In addition, hydrogen piping 31
On / off valves 33 and 34 for controlling the flow of hydrogen are provided on the valve 32. The on / off valves 33 and 34 are controlled by a signal from the control unit 80 as shown in FIG. (Operation) The process of recovering cold from the hydrogen storage alloy tank 17b (FIG. 1)
And FIG. 3) In this process, a regeneration process is performed between the II 'system and the III-III' system, and a cold heat generation process is performed between the II-II 'system and the IV-IV' system. . Specifically, it is as follows.

First, in the II 'system, the control unit 80
The flow control valve 5 and the switching valve 7 are driven by the drive signal from the circulating pump 11, and the high-temperature heat medium 9 (130 to
(150 ° C.) is supplied to the heat exchanger 2a (that is, the high-temperature heat medium 9 flows through the heat medium pipe 3a → the heat medium pipe 3b → the heat exchanger 2a → the heat medium pipe 3c → the heat medium pipe 3d). On the other hand, III-II
In the I ′ system, the switching valve 21 and the switching valve 23 are driven by a drive signal from the control unit 80, and the circulating pump 2
5 from the heat exchanger 27 (20 to 25 ° C.)
8a (that is, the low-temperature heat medium 27 is supplied to the heat medium pipe 19).
a → heat medium pipe 19b → heat exchanger 18a → heat medium pipe 19c → heat medium pipe 19d).

In this case, the hydrogen storage alloy MH1A in the hydrogen storage alloy tank 1a has the hydrogen dissociation characteristic A shown in FIG. 7, and the temperature is raised to 130 to 150 ° C. by the high-temperature heat medium 9. The state shown by point A in 7 is obtained.
On the other hand, the hydrogen storage alloy MH2C in the hydrogen storage alloy tank 17a
Has a hydrogen absorption characteristic b 'shown in FIG. 7 and its temperature is lowered to 20 to 25 ° C. by the low-temperature heat medium 27, so that a state shown by a point C in FIG. 7 is obtained. In this case, since the pressure at point C <the pressure at point A, the hydrogen storage alloy MH
1A is in a state capable of generating hydrogen at point A, while the hydrogen storage alloy MH2C is in a state capable of storing hydrogen at point C. As a result, when the on-off valve 33 of the hydrogen pipe 31 is opened, the hydrogen generated in the hydrogen storage alloy MH1A moves from the hydrogen storage alloy tank 1a to the hydrogen storage alloy tank 17a via the hydrogen pipe 31 and is transferred to the hydrogen storage alloy MH2C. It is occluded and reaches a renewable state. In this case, heat is generated from the hydrogen storage alloy MH2C. However, since this heat is removed by the cooling water 27, the temperature of the hydrogen storage alloy MH2C does not rise much.

On the other hand, in the II-II 'system, the flow control valve 6 and the switching valve 8 are driven by the drive signal from the control unit 80, and the low-temperature heat medium 10 from the circulation pump 12 is sent to the heat exchanger 2b. Supply (that is, the low-temperature heat medium 10 flows in the order of the heat medium pipe 4a → the heat medium pipe 4b → the heat exchanger 2b → the heat medium pipe 4c → the heat medium pipe 4d). On the other hand, in the IV-IV 'system, the switching valve 22 and the switching valve 24 are driven by the drive signal from the control unit 80, and the return heat medium 30 from the heat load such as the freezing warehouse is heat-exchanged by the circulation pump 26. Vessel 18b
(That is, the return heat medium 30 is connected to the heat medium pipe 20a →
The heat medium pipe 20b → the heat exchanger 18b → the heat medium pipe 20c → the heat medium pipe 20d).

In this case, the hydrogen storage alloy MH1B in the hydrogen storage alloy tank 1b has the hydrogen storage characteristics a 'shown in FIG. 7 and the temperature is lowered to 20 to 25 ° C. by the low-temperature heat medium 10. The state shown by the point B in FIG. 7 is obtained.
On the other hand, the hydrogen storage alloy MH2D in the hydrogen storage alloy tank 17b
Has a hydrogen dissociation characteristic b shown in FIG. 7 and is brought to a temperature of about −20 ° C. by the return heat medium 30.
The state shown by point D in FIG. 7 is obtained. In this case, since the pressure at point B <the pressure at point D, the hydrogen storage alloy MH1B
Is in a state capable of storing hydrogen at point B, while the hydrogen storage alloy MH2D is in a state capable of releasing hydrogen at point D. As a result,
When the on-off valve 33 of the hydrogen pipe 31 is opened, the hydrogen generated in the hydrogen storage alloy MH2D moves from the hydrogen storage alloy tank 17b to the hydrogen storage alloy tank 1b via the hydrogen pipe 31, and is stored in the hydrogen storage alloy MH1B. . Thus, when hydrogen is released from the hydrogen storage alloy MH2D, the hydrogen storage alloy MH2D is released.
Due to the 2D endothermic reaction, the temperature of the heat medium 30 is lowered in the heat exchanger 18b, and cold heat is extracted. Then, refrigeration is performed by supplying the cold heat to a heat load in a freezing warehouse or the like. In the above case, heat is generated from the hydrogen storage alloy MH1B, but since this heat is removed by the cooling water 10, the temperature of the hydrogen storage alloy MH1B does not rise so much. Step of recovering cold from the hydrogen storage alloy tank 17a (FIG. 1)
And FIG. 6) When the hydrogen transfer in both processes is completed, the on-off valve 33
After closing the block 34 to prevent the movement of hydrogen, the following control is performed to perform continuous operation.

That is, a regeneration process is performed between the II 'system and the III-III' system, and a cold heat generation process is performed between the II-II 'system and the IV-IV' system. Specifically, I
In the -I 'system and the II-II' system, the high-temperature heat medium 9 is supplied to the heat exchanger 2b while the low-temperature heat medium 10 is heated by switching the flow control valves 5.6 and the switching valves 7.8. Exchanger 2a
(Ie, the high-temperature heat medium 9 is supplied from the heat medium pipe 3a → the branch heat medium pipe 40a → the heat medium pipe 4b → the heat exchanger 2b → the heat medium pipe 4c).
→ Branch heat medium pipe 41b → Flow through heat medium pipe 3d, low-temperature heat medium 1
0 indicates the heat medium pipe 4a → the branch heat medium pipe 40b → the heat medium pipe 3b → the heat exchanger 2a → the heat medium pipe 3c → the branch heat medium pipe 41a → the heat medium pipe 4
d). On the other hand, III-III 'system and IV-I
In the V 'system, the switching valves 21 and 22 and the switching valves 23.2
4 to supply the low-temperature heat medium 27 to the heat exchanger 18b, while supplying the return heat medium 30 to the heat exchanger 18a (that is, the low-temperature heat medium 27 is supplied from the heat medium pipe 19a to the branch heat medium pipe). 50a → heat medium pipe 20b → heat exchanger 18b → heat medium pipe 2
0c → branch heat medium pipe 51b → heat medium pipe 19d, return heat medium 30 is heat medium pipe 20a → branch heat medium pipe 50b → heat medium pipe 19b → heat exchanger 18a → heat medium pipe 19c → branch heat medium. Tube 5
1a → flows through the heat medium pipe 20d). Thereby, cold heat is collected from the hydrogen storage alloy tank 17a. Switching between the above-mentioned steps and the above-described steps When switching between the above-mentioned steps and the above-mentioned steps (that is, FIG. 3)
When the process shifts from the process of FIG. 6 to the process of FIG. 6, the degree of opening and closing of the heat switching valves 5 and 6 is controlled as shown in FIGS.
Specifically, as shown in FIG. 4, the high-temperature heat medium 9 is branched into the branch flows 60 and 61. At the beginning of the switching, the amount of the branch flow 60 is increased and the amount of the branch flow 61 is reduced.
In addition, the low-temperature heat medium 10 is branched into the branched flows 62 and 63. At the beginning of the switching, the amount of the branched flow 63 is increased and the amount of the branched flow 62 is reduced. Then, the branch flow 60
And the branch stream 62 are mixed, but the amount of the branch stream 60 is large, so that the temperature of the heat medium supplied to the heat exchanger 2a does not change much. On the other hand, the branch stream 61 and the branch stream 63 are also mixed, but since the amount of the branch stream 63 is large, the temperature of the heat medium supplied to the heat exchanger 2b does not change much. As the heat exchangers 2a and 2b warm (or are cooled), as shown in FIG. 5, the amount of the branch flow 60 is reduced, the amount of the branch flow 61 is increased, and the amount of the branch flow 63 is increased. And the amount of the branch stream 62 is increased. If you do this,
Since the temperature of the heat exchangers 2a and 2b can be prevented from increasing or decreasing rapidly, thermal shock is reduced. The ratio of the branched flows 60 to 63 is controlled by measuring the temperatures of the heat medium flowing into the heat exchangers 2a and 2b by the temperature sensors 70 and 71, respectively, so that the rate of change does not exceed a predetermined value. The control is performed by the unit 80.

By the way, in order to examine the reliability of the cooling and heating system, the following prototype was prepared and subjected to a reliability test. [Invention] The hydrogen storage alloy tank 1a, 1b, 17a, 1
7b each 2kg of hydrogen storage alloy MH1A ・ MH1B ・ M
H2C / MH2D and the heat exchanger 2a
A system was prototyped using copper tubes with outer diameter of 6.35 mm and thickness of 0.3 mm for 2b, 17a and 17b. The control of the temperature of the heat medium flowing into the heat exchangers 2a and 2b was performed by the above method.

Hereinafter, this system is referred to as a system I. COMPARATIVE EXAMPLE A system similar to the system I of the present invention described above was prototyped, except that the heat medium flowing into the heat exchangers 2a and 2b was switched by the conventional method (see FIGS. 8 and 9). Hereinafter, this system is referred to as system II.

[Experiment] The temperature of the heat medium flowing into the heat exchanger of the system I of the present invention and the system II of the comparative example and the state of metal fatigue of the heat exchanger were examined. The experimental conditions were
The condition is that a medium having a temperature of 150 ° C. is used as a high-temperature heat medium and a medium having a temperature of 20 ° C. is used as a low-temperature heat medium, and that both heat mediums are switched every 20 minutes.

In the system II, the temperature of the heat medium flowing into the heat exchanger was abrupt as shown in FIG. 11, and the maximum temperature change rate was 100 ° C./sec or more. This rate of change is very large, and the metal fatigue due to thermal shock seems to be considerable. In fact, in this operation, 100 to 200
After the continuous operation for a long time, it was confirmed that cracks occurred in the heat exchanger.

On the other hand, in the system I, the temperature of the heat medium flowing into the heat exchanger is slower than that in the system II as shown in FIG. 8 (the temperature change rate is controlled so as not to exceed 10 ° C./sec). Therefore, impact heat is greatly reduced.
In this operation, no crack was generated in the heat exchanger even after the long-term continuous operation for 500 hours. In the above case,
Since the switching of the heat medium in the system I is completed in about 10 to 30 seconds, the influence on the heat output and the heat efficiency is negligibly small.

[Other Matters] In the above embodiment, the temperature of the heat medium flowing into the heat exchanger is adjusted by changing the open / close ratio of the switching valve. However, the present invention is not limited to such a method. It is also possible to provide a flow rate sensor instead of the sensor and to reduce the thermal shock by changing the flow rate of the circulation pump and adjusting the amount of the heat medium flowing into the heat exchanger. Further, by controlling in this way, it is possible to apply to a refrigeration system using only one set of two types of hydrogen storage alloys.

[0029]

As described above, according to the present invention, the thermal shock to the heat exchanger is reduced and the heat exchanger can be prevented from being broken due to metal fatigue. As a result, there is an effect that the reliability of the heat utilization system can be dramatically improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cooling and heating system using two sets of two types of hydrogen storage alloys.

FIG. 2 is a block diagram showing a temperature control mechanism of a heat medium.

FIG. 3 is an explanatory view showing a process of generating cold heat in the II ′ system and the II-II ′ system.

FIG. 4 is an explanatory diagram when heat supply is switched in the II ′ system and the II-II ′ system.

FIG. 5 is an explanatory diagram at the time of heat supply switching in the II ′ system and the II-II ′ system.

FIG. 6 is an explanatory diagram showing a regeneration process in the II ′ and II-II ′ systems.

FIG. 7 is a thermal cycle diagram shown on an equilibrium characteristic diagram of van't Hoff.

FIG. 8 is a graph showing a temperature change of a supply heat medium in the heat utilization system of the present invention.

FIG. 9 is an explanatory diagram showing a cold heat generation process in a conventional heat utilization system.

FIG. 10 is an explanatory diagram showing a regeneration process in a conventional heat utilization system.

FIG. 11 is a graph showing a temperature change of a supply heat medium in a conventional heat utilization system.

[Explanation of symbols]

 1a hydrogen storage alloy tank 1b hydrogen storage alloy tank 2a heat exchanger 2b heat exchanger 5 flow control valve 6 flow control valve 9 high temperature heat medium 10 low temperature heat medium 70 temperature sensor 71 temperature sensor 80 control unit MH1A hydrogen storage alloy MH1B hydrogen storage alloy

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Furukawa 2-18 Keihanhondori, Moriguchi City Sanyo Electric Co., Ltd. (56) References JP-A-2-110263 (JP, A) JP-A-4 −151471 (JP, A)

Claims (1)

(57) [Claims] 1. A heat utilization system for storing and releasing hydrogen gas in a hydrogen storage alloy by alternately supplying heat mediums having different temperature levels supplied from a plurality of heat medium supply means to the hydrogen storage alloy. Temperature measuring means for measuring the temperature of the heat medium supplied to the alloy; and a rate of change in temperature of the heat medium supplied from the heat medium to the hydrogen storage alloy when the heat medium supply is switched based on the detection result of the temperature measurement means. Control means for controlling the heat medium supply means so as to be less than or equal to a value.