JP2002168541A - Heat utilizing system employing hydrogen occlusion material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance heat utilizing efficiency of a heat utilizing system having heat utilizing cycles employing an exothermic reaction and an endothermic reaction occurring at the time when a hydrogen occlusion material occludes and releases hydrogen. SOLUTION: The heat utilizing system has a regenerative heat exchanger provided on at least one site of hydrogen transfer pipes connecting first heat exchanger vessels and second heat exchanger vessels of the heat utilizing cycles, and a hydrogen bypass pipe mutually connecting the first heat exchanger vessels or the second heat exchanger vessels of the respective heat utilizing systems. Preferably, a heat exchanger for effecting heat exchange between a heat medium and hydrogen is further provided on at least either one of the first heat exchanger vessels or the second heat exchanger vessels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat utilization system such as a heat pump or a refrigerating device utilizing a heat generation function and a heat absorption function when a hydrogen storage material stores and releases hydrogen.

[0002]

2. Description of the Related Art A heat utilization system such as a heat pump system using a hydrogen storage material has lower vibration, lower noise, lower power consumption, more effective use of waste energy, and environmental load, as compared with a compression type or an absorption type. From the standpoint of reduction of the amount of water. A conventional general heat pump device using a metal hydride as a hydrogen storage material will be described below. FIG. 4 shows a schematic configuration diagram of the apparatus, and FIG. 5 shows the cycle characteristics of temperature and equilibrium pressure of the system. In FIG. 5, the vertical axis represents the equilibrium pressure, the horizontal axis represents the reciprocal of the temperature, and the lower the temperature, the lower the temperature.

FIG. 4 is a block diagram of a heat pump system including a pair of connected heat utilization cycles. First, the configuration and operation of the first set of heat utilization cycles will be described. This heat utilization cycle is the first heat exchange vessel MH1
(1) and a second heat exchange vessel MH3 (3).
The hydrogen transfer pipe 4 communicates between (1) and MH3 (3). The heat generated when the hydrogen is occluded and released by the hydrogen storage material in the MH1 (1) and the MH3 (3) and the heat generated by the endothermic reaction are generated by the heat medium flowing through the heat medium pipes (5 and 6). Heat is transferred to heat exchangers (7 and 8), where heat exchange with the outside takes place.

In this heat utilization cycle, two types of hydrogen storage materials are used. MH3 (3) has a high equilibrium pressure at the same temperature and MH1 (1) has a high equilibrium pressure at a high temperature. A low-temperature hydrogen storage material higher than the hydrogen storage material is stored. When a high-temperature heat source is input to MH3 (3) and the temperature is raised to Th as shown in FIG. 5, the equilibrium pressure of the high-temperature hydrogen storage material increases from the point D to the equilibrium pressure at the point A. As a result, the equilibrium pressure of the high-temperature hydrogen storage material becomes higher than the pressure in MH1 (1) containing the low-temperature hydrogen storage material having the equilibrium pressure at point B at the temperature Tm, and the pressure difference causes the hydrogen to become MH3. Move from (3) to MH1 (1).
At this time, in MH1 (1), heat can be obtained by an exothermic reaction caused by the hydrogen storage material storing hydrogen.

Next, as shown in FIG. 5, when the temperature of MH3 (3) is lowered to Tm, the pressure in MH3 (3) drops to the equilibrium pressure at point D, and MH3 (3) is supplied from MH1 (1) side. The hydrogen moves to the side. At this time, in MH1 (1), the temperature decreases to Tc due to an endothermic reaction by releasing hydrogen, and in MH1 (1), cold heat can be obtained. At the same time, MH3 (3) generates heat due to an exothermic reaction that absorbs hydrogen. By repeating this series of operations, cooling and heating hot water supply can be performed.

[0006] In the above-mentioned first set of heat utilization cycles provided with MH3 (3) and MH1 (1), a first heat exchange vessel MH1 '(1') containing a low-temperature hydrogen storage material and a high-temperature high-temperature storage vessel are used. Heat exchange container MH3 '(3') containing hydrogen storage material for use
The heat pump system shown in FIG. 4 is configured by connecting the second set of heat utilization cycles having the following. When the operation of each heat utilization cycle of the heat pump system is performed in the opposite phase, it is possible to continuously obtain cold and warm heat. Heat generated when hydrogen is absorbed and released by the hydrogen storage material in the MH1 ′ (1 ′) and MH3 ′ (3 ′) and heat generated by the endothermic reaction are respectively generated by the heat medium flowing through the pipes (10 and 11). The heat is transferred to external heat exchangers (12 and 13), where heat exchange with the outside takes place. MH1 (1) and MH
1 ′ (1 ′), MH3 (3), and MH3 ′ (3 ′) are configured to be able to exchange heat with the heat medium pipes (14 and 15), respectively.

In the above heat pump system, the sensible heat loss due to the repetition of temperature rise and fall of each hydrogen storage material is large, and the heat utilization efficiency (ratio of output heat to input heat) is particularly low during cooling. was there.
As one method for solving this problem, for example, Japanese Patent Application Laid-Open No. Sho 60-17669 discloses an example of a double effect heat pump system using three types of hydrogen storage materials having different temperature / equilibrium pressure characteristics. ing.

This is because heat exchange containers MH1 and MH3 containing the two types of hydrogen storage materials for high temperature and low temperature use heat exchange container MH2 containing the hydrogen storage material for medium temperature. And a heat utilization cycle composed of a heat exchange container MH1 'containing a low-temperature hydrogen storage material. In this system, as shown in FIG.
A → B → C → D, A ′ → B ′ → C ′ where operation is in opposite phase
→ Heating and cooling water supply is performed in two sets of heat utilization cycles of D '.

In this heat pump system, the temperature T
The heat generated from MH3 at h ′ (point D) is calculated as M at temperature Tm ′.
Since the configuration is such that the heat is supplied to H2 (point A '), heat only needs to be supplied to MH3 in the entire system, so that the heat utilization efficiency during cooling can be particularly improved. With this double effect heat pump system, some improvement in heat utilization efficiency can be expected. However, in recent years, the performance of conventional heat utilization systems, such as compression-type and absorption-type heat pump systems, has been greatly improved.To realize a heat utilization system using a hydrogen storage material that surpasses these performances, Further improvement in heat utilization efficiency is required.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of a heat utilization system using a hydrogen storage material and to further improve the heat utilization efficiency.

[0011]

The heat utilization system of the present invention utilizes at least one heat utilization cycle utilizing heat generation and endothermic reaction when hydrogen is absorbed and released by the hydrogen storage material. The system, wherein the heat utilization cycle includes: a first heat exchange container containing a first hydrogen storage material;
A second heat exchange container accommodating a second hydrogen storage material, and a hydrogen transfer pipe connecting the first heat exchange container and the second heat exchange container. At least one heat storage type heat exchanger.

Further, the heat utilization system of the present invention is a heat utilization system provided with a plurality of heat utilization cycles utilizing heat generation and an endothermic reaction when hydrogen is occluded and released in the hydrogen storage material. The heat utilization cycle of each set includes a first heat exchange container containing a first hydrogen storage material, a second heat exchange container containing a second hydrogen storage material, and the first heat exchange container. And a hydrogen transfer pipe connecting the second heat exchange container, and between the first heat exchange containers in the plurality of heat utilization cycles, the plurality of heat utilization cycles in the heat utilization cycle. A bypass pipe for hydrogen transfer is provided between at least one of the second heat exchange vessels and at least one of the pipes for hydrogen transfer in the plurality of heat utilization cycles. , At least one Those having a regenerative heat exchanger.

Further, the heat utilization system of the present invention is a heat utilization system provided with at least one heat utilization cycle utilizing heat generation and endothermic reaction when hydrogen is absorbed and released in the hydrogen storage material, The heat utilization cycle includes a first heat exchange container containing a first hydrogen storage material, a second heat exchange container containing a second hydrogen storage material, and the first heat exchange container and the second heat exchange container. A hydrogen transfer pipe that connects the heat exchange container to the heat exchange container, and a heat medium that transfers heat to the heat exchange container to at least one of the first and second heat exchange containers in the heat utilization cycle. And a heat exchanger for exchanging heat with hydrogen flowing into and out of the heat exchange container.

Further, the heat utilization system of the present invention is a heat utilization system having two sets of the heat utilization cycles,
The equilibrium pressures of the second hydrogen storage materials in the two sets of heat utilization cycles are different from each other at the same temperature, and these equilibrium pressures are the respective first hydrogens in the two sets of heat utilization cycles. It is lower than the equilibrium pressure of the storage material at the same temperature.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a heat utilization system using a hydrogen storage material according to the present invention will be described with reference to specific examples. The heat utilization system exemplified in each embodiment includes a first heat exchange container MH1 containing a first low-temperature hydrogen storage material and a second heat exchange container MH3 containing a high-temperature hydrogen storage material. One set of heat utilization cycle, and a second set including a first heat exchange container MH1 'containing a second low-temperature hydrogen storage material and a second heat exchange container MH2 containing a medium-temperature hydrogen storage material. This is a dual-effect heat utilization system composed of a heat utilization cycle. Each heat exchange container of this heat utilization system contains hydrogen storage materials having different temperature and equilibrium pressure characteristics, and the equilibrium pressure is the same, and the high-temperature hydrogen storage material <medium-temperature hydrogen storage material < There is a relationship between the first and second low-temperature hydrogen storage materials. However, the first and second low-temperature hydrogen storage materials may have slightly different equilibrium pressures or the same equilibrium pressure at the same temperature.

The configuration of each embodiment of the heat utilization system of the present invention described below is the same as that of the conventional heat pump system described with reference to FIG. Therefore,
The same parts as those in the conventional example will be described with the same reference numerals.

Embodiment 1 The configuration of a heat utilization system according to Embodiment 1 will be described with reference to the block diagram of FIG. FIG.
As shown in FIG. 5, the first set of heat utilization cycles includes heat exchange vessels MH1 (1) and MH3 (3), and MH1 (1) and M
H3 (3) is connected by a hydrogen transfer pipe (4) provided with a regenerative heat exchanger (17). However, hydrogen is M
The heat generated by the heat absorption and endothermic reaction when occluded and released by the hydrogen storage material in H1 (1) and MH3 (3) is exchanged by the heat medium flowing through the heat medium pipes (5 and 6) for external heat exchange. (7 and 8) where heat exchange with the outside takes place.

Further, the second set of heat utilization cycles is the above-mentioned M cycle.
A low-temperature heat exchange vessel MH1 '(1') and MH2 (2) are provided separately from H1 (1), and MH1 '(1') and MH2 (2) are provided with a regenerative heat exchanger (18). It is connected by the provided hydrogen transfer pipe (9). However, hydrogen is MH1 '
The heat generated by the heat absorption and endothermic reaction when occluded and released by (1 ′) and the hydrogen occlusion material in MH2 (2) is exchanged by the heat medium flowing through the heat medium pipes (10 and 11). (12 and 13) where heat exchange with the outside takes place. Note that MH1 (1) and MH1 ′ (1 ′),
MH2 (2) and MH3 (3) are each connected to a heat medium pipe (1
4 and 15) can be used for heat exchange.

Next, the operation of the heat utilization system will be described with reference to FIG. First, in operation mode 1,
In the first set of heat utilization cycles, high-temperature heat from the external heat exchanger (7) is input to MH3 (3), and MH3
The temperature of (3) is raised to Th. Then, MH3
The pressure of (3) also rises and becomes higher than the pressure of MH1 (1), and due to this pressure difference, hydrogen is stored in the regenerative heat exchanger (17).
Through the hydrogen transfer pipe (4), and from MH3 (3) to M
Move to H1 (1). At this time, in MH1 (1), heat can be obtained by an exothermic reaction caused by the hydrogen storage material storing hydrogen. This heat is transferred to the external heat exchanger (8) by the heat medium through the heat medium pipe (6) and used for heating and hot water supply. High temperature (T
By passing the hydrogen of h) through the regenerative heat exchanger (17), heat from the high-temperature hydrogen is temporarily stored therein.

On the other hand, in the second set of heat utilization cycles,
When MH2 (2) is cooled by the external heat exchanger (12) and the temperature of MH2 (2) is reduced, the pressure of MH2 (2) also decreases and becomes lower than the pressure of MH1 '(1'). Due to this pressure difference, hydrogen moves from MH1 ′ (1 ′) to MH2 (2) through the hydrogen transfer pipe (9). At this time, in the MH1 ′ (1 ′), cold heat can be obtained by an endothermic reaction caused by the hydrogen storage material releasing hydrogen. This cold heat is carried by the heat medium to the external heat exchanger (13) through the heat medium pipe (11) and used for cooling and freezing. Further, in MH2 (2), heat can be obtained by an exothermic reaction caused by the hydrogen storage material storing hydrogen. This heat is transferred to an external heat exchanger (12) through a pipe (10) by a heat medium, and can be used for heating or hot water supply. Further, hydrogen is warmed by the heat stored in the regenerative heat exchanger (18) in the operation mode 3 described later,
For this reason, in MH2 (2), a large amount of heat can be obtained.

Next, in the operation mode 2, the temperature of each heat exchange vessel is changed in order to move hydrogen in the operation mode 3 in the opposite direction to the operation mode 1. At this time, in order to increase the heat utilization efficiency, the sensible heat of each heat exchange container is recovered using the temperature difference of each heat exchange container. At this time, the hydrogen transfer pipes (4 and 9) and the heat medium pipes (5, 10, 6 and 11) are closed. The MH3 (3) and the MH2 (2) are communicated with each other through the heat medium pipe (14), and heat is transferred from the higher temperature MH3 (3) side to the lower temperature MH2 (2) side by the heat medium to recover heat. I do. Thereby, the temperature and the pressure on the MH3 (3) side decrease, and the temperature and the pressure on the MH2 (2) side increase. Similarly, M
H1 (1) and MH1 ′ (1 ′) are communicated by a heat medium pipe (15), and heat is transferred from the high temperature MH1 (1) side to the low temperature MH1 ′ (1 ′) side by the heat medium. To recover heat. Thereby, the temperature and the pressure on the MH1 (1) side decrease, and the temperature and the pressure on the MH1 ′ (1 ′) increase.

Further, in operation mode 3, the first set of heat utilization cycles and the second set of heat utilization cycles correspond to operation mode 1
Moves in the opposite direction of the time. In other words, due to the pressure difference generated in the operation mode 2, the MH3 (3) passes through the hydrogen transfer pipe (4) and the regenerative heat exchanger (17) from the MH1 (1) side.
Hydrogen from the MH2 (2) side through the regenerative heat exchanger (18) and the hydrogen transfer pipe (9).
Hydrogen moves to the 1 ′ (1 ′) side. At this time, the pipes (5 and 10) are closed, but due to the movement of hydrogen as described above, heat of occlusion is continuously generated in the MH3 (3), and the heat is transferred to the heat medium pipe (14). ) To the MH2 (2) side to cope with endothermic due to hydrogen release on the MH2 (2) side. In addition, since the heat stored in the regenerative heat exchanger (17) in the operation mode 1 can also be used, the amount of heat transferred to the MH2 (2) can be increased. Further, the temperature T out of MH2 (2)
The heat of the hydrogen of m 'is temporarily stored in the regenerative heat exchanger (18). At this time, the generated exothermic reaction and endothermic reaction
MH1 (1) performs cooling, and MH1 ′ (1 ′) performs heating and hot water supply.

Next, in operation mode 4, sensible heat recovery is performed as in operation mode 2. The heat medium pipes (6 and 11) are closed, MH1 (1) and MH1 ′ (1 ′) are communicated with each other through the heat medium pipe (15), and the MH1 ′ having a higher temperature is heated by the heat medium.
The heat is transferred from the (1 ′) side to the lower temperature MH1 (19) side to recover the heat. Thus, the temperature and pressure on the MH1 '(1') side decrease, and the temperature and pressure on the MH1 (1) side increase. On the other hand, since the temperature of MH3 (3) is higher than the temperature of MH2 (2), heat is transferred from MH2 (2) to MH3 (3) to increase the temperature of MH3 (3), and to reduce the temperature of MH2 (2). I can't lower it. Therefore, the heating medium pipes (5 and 10) are communicated to perform preheating and precooling, respectively, to raise the temperature and pressure on the MH3 (3) side, and to make the MH2 (2)
Lower side temperature and pressure. Note that, in the heat utilization system having a configuration in which the system shown in FIG.
3 (3) and MH2 (2) are each two, and each MH
Sensible heat recovery can be performed between 3 and between each MH2.

By operating the heat utilization system having such a configuration by repeating the above operation modes 1 to 4,
The heat stored in the regenerative heat exchanger is effectively used, the heat loss due to hydrogen gas can be reduced, and the heat utilization efficiency can be improved.

Embodiment 2 The configuration of a heat utilization system according to Embodiment 2 will be described with reference to the block diagram of FIG. In this heat utilization system, hydrogen transfer pipes (4 and 9) of MH3 (3) and MH2 (2) are connected by a bypass pipe (16), and a regenerative heat exchanger (19) is connected to a hydrogen transfer pipe ( The configuration is the same as that of the first embodiment, except that it is incorporated in the bypass pipe (16) instead of 4 and 9). The operation of this heat utilization system is the same as that of the first embodiment except that the operation mode of the sensible heat recovery is different. Therefore, only the operation modes 2 and 4 will be described below.

In operation modes 2 and 4, MH3 (3)
And the MH2 (2) hydrogen transfer pipes (4 and 9) are closed by valves, and the MH3
(3) and MH2 (2) are connected. At this time, hydrogen is MH
3 (3) and move only between MH2 (2). In the operation mode 2, since the pressure on the MH3 (3) side is higher than that on the MH2 (2) side, hydrogen flows from the MH3 (3) to the MH2 (2) side. Is higher than the MH3 (3) side, hydrogen flows from the MH2 (2) to the MH3 (3) side. In operation mode 2, MH3
The heat of the high-temperature hydrogen moving from (3) to MH2 (2) is stored in the regenerative heat exchanger (19), and in the operation mode (4), the stored heat is transferred from MH2 (2) to MH3 (3).
The hydrogen flowing into the side receives.

After the transfer of the hydrogen, if necessary, the bypass pipe (16) is closed, and the heat medium pipe (15) is communicated.
Sensible heat recovery is further performed between MH1 (1) and MH1 ′ (1). Since the temperature of MH3 (3) is higher than that of MH2 (2), the MH2 (3) is simply
Although sensible heat recovery from (2) to MH3 (3) is not possible, by adopting the above configuration, by opening the bypass pipe (16) and moving hydrogen from MH2 (2) to MH3 (3), The temperature of MH3 (3) can be increased.
Further, in the present embodiment, since the sensible heat in the hydrogen gas is used effectively, the sensible heat can be recovered quickly, and the heat utilization efficiency of the system is improved.

Embodiment 3 The configuration of a heat utilization system according to Embodiment 3 will be described with reference to the block diagram of FIG. This heat utilization system uses MH1 without a regenerative heat exchanger.
(1) A heat exchanger (20 and 2) for exchanging heat between the heat medium in the heat medium pipe and hydrogen at the inlet / outlet of hydrogen of MH1 ′ (1 ′).
The configuration is the same as that of the first embodiment except that 1) is provided.
In the operation mode of the heat utilization system, in operation modes 1 and 3, for example, when hydrogen is released from MH1 (1) and MH1 ′ (1 ′), MH1 (1) and MH1 ′
At the same time as the temperature of (1 ′) decreases, the temperature of the hydrogen gas also decreases. The cold heat of the hydrogen gas is recovered to the heat medium side by the heat exchangers (20 and 21). In this way, the sensible heat in the hydrogen gas can be used effectively, and the heat utilization efficiency of the system can be improved.

In the heat utilization system of each of the above embodiments, two types of hydrogen storage materials used for each set of heat utilization cycles,
The hydrogen storage materials in the first heat exchange container of the different sets of heat utilization cycles and the hydrogen storage materials in the second heat exchange container of the different sets use different equilibrium pressures at the same temperature. However, the relationship between the equilibrium pressures of these hydrogen storage materials at the same temperature does not necessarily have to be based on the above relationship. Further, the heat utilization system according to the present invention is not limited to one having two sets of heat utilization cycles, and may be one set, or three or more sets of heat utilization cycles.
For example, if the heat utilization system has three heat utilization cycles, the hydrogen storage material in the first heat exchange vessel in the first heat utilization cycle and the first heat utilization cycle in the second heat utilization cycle. The equilibrium pressure with the hydrogen storage material in the heat exchange container may be the same at the same temperature, and the hydrogen storage material in the first heat exchange container in the third heat utilization cycle may be different. Note that the regenerative heat exchanger used in each of the above embodiments is also called a regenerator, and for example, a heat exchanger in which fine wires, small balls, tubes, and the like are filled can be used.

FIG. 1 for explaining each of the above embodiments.
Although the valves and pumps are not shown in the block diagrams of FIGS. 1 to 3, they may be installed as needed. Also, a configuration may be adopted in which a switching valve is provided and shared, instead of separately providing a heating medium pipe for sensible heat recovery and heat utilization. Furthermore, various heat utilization systems according to the present invention can be configured by combining the first to third embodiments.

[0031]

According to the heat utilization system of the present invention, the sensible heat in the hydrogen gas can be efficiently recovered, so that the heat utilization efficiency of the system can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a heat utilization system according to an embodiment of the present invention.

FIG. 2 is a block diagram of a heat utilization system according to another embodiment of the present invention.

FIG. 3 is a block diagram of a heat utilization system according to still another embodiment of the present invention.

FIG. 4 is a block diagram of a conventional heat utilization system.

FIG. 5 is a diagram showing cycle characteristics of temperature and equilibrium pressure in a heat utilization cycle.

FIG. 6 is a diagram showing cycle characteristics of a heat utilization system including two sets of heat utilization cycles.

[Description of Signs] 1 Heat exchange vessel (MH1) 1 'Heat exchange vessel (MH1') 2 Heat exchange vessel (MH2) 3 Heat exchange vessel (MH3) 3 'Heat exchange vessel (MH3') 4, 9 For hydrogen transfer Pipes 5, 6, 10, 11, 14, 15 Heat medium pipes 7, 8, 12, 13 External heat exchangers 16 Bypass pipes 17, 18, 19 Heat storage heat exchangers 20, 21 Heat exchangers

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiaki Yamamoto 1006 Kadoma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F term (reference) 3L093 NN05 PP03

Claims (4)

[Claims] 1. A heat utilization system comprising at least one heat utilization cycle utilizing heat generation and an endothermic reaction when hydrogen is stored and released in a hydrogen storage material, wherein the heat utilization cycle comprises: A first heat exchange container containing one hydrogen storage material, a second heat exchange container containing a second hydrogen storage material,
And a hydrogen transfer pipe that connects the first heat exchange container and the second heat exchange container, and the hydrogen transfer pipe includes at least one regenerative heat exchanger. 2. A heat utilization system having a plurality of sets of heat utilization cycles utilizing heat generation and endothermic reactions when hydrogen is stored and released in a hydrogen storage material, wherein each set of heat utilization cycles is A first heat exchange container containing a first hydrogen storage material, a second heat exchange container containing a second hydrogen storage material, and the first heat exchange container and the second heat exchange container Each of which has a hydrogen transfer pipe connecting the first heat exchange vessels in the heat utilization cycle of each set, the second heat exchange vessels, and the hydrogen transfer pipe. A heat utilization system comprising a bypass pipe for hydrogen transfer provided in at least one location between the pipes, and including at least one regenerative heat exchanger in the bypass pipe. 3. A heat utilization system having at least one heat utilization cycle utilizing heat generation and an endothermic reaction when hydrogen is stored and released in a hydrogen storage material, wherein the heat utilization cycle includes a first heat utilization cycle. A first heat exchange container containing one hydrogen storage material, a second heat exchange container containing a second hydrogen storage material,
And a hydrogen transfer pipe for transferring hydrogen between the first heat exchange container and the second heat exchange container, wherein the first heat exchange container and the second heat in the heat utilization cycle are provided. A heat utilization system comprising, on at least one of the exchange vessels, a heat exchanger for exchanging heat between a heat medium for transferring heat to the heat exchange vessel and hydrogen flowing into and out of the heat exchange vessel. 4. The heat utilization system having two heat utilization cycles, wherein equilibrium pressures of the second hydrogen storage materials in the two heat utilization cycles are different from each other at the same temperature, The heat utilization system according to any one of claims 1 to 3, wherein the equilibrium pressure is lower than the equilibrium pressure of each of the first hydrogen storage materials in each of the two sets of heat utilization cycles at the same temperature.