JP4953194B2 - Hydrogen storage tank - Google Patents

Description

  The present invention relates to a hydrogen storage tank, and more particularly to a hydrogen storage tank suitable for storing and releasing hydrogen using a hydrogen storage alloy.

  Conventionally, for example, when storing hydrogen gas, it has been widely practiced to compress the hydrogen gas and fill it into a cylinder, or store it in a hydrogen storage alloy or a hydrogen adsorbing material capable of storing hydrogen.

  However, the cylinder has a small wall capacity because the wall thickness is large for a large volume. In general, a hydrogen storage alloy or the like does not necessarily have a high hydrogen storage density. For example, when it is mounted on a vehicle, it is difficult to satisfy a required storage density. For this reason, various studies have been made on techniques for increasing the packing density of hydrogen storage alloys and storing a large amount of hydrogen.

On the other hand, a hydrogen storage alloy (MH) generally undergoes an occlusion reaction (exothermic reaction) when cooled and pressurized with hydrogen, and conversely, an exothermic reaction (endothermic reaction) proceeds when the alloy is heated under reduced pressure. It is known that a heat transfer is involved in the absorption and release of water. In a usage mode in which hydrogen is temporarily stored and hydrogen is released as needed, it is important that heat transfer is performed well in order to store or release a large amount of hydrogen.
That is, the hydrogen storage alloy consumes sensible heat when releasing hydrogen and the temperature decreases. When this temperature decrease increases, the hydrogen release rate decreases. Conversely, when hydrogen is stored, heat is generated and this temperature increase As the value increases, the hydrogen storage rate also decreases and the reaction rate decreases.

In relation to the above, as one of the techniques for supplying hydrogen occluded using a hydrogen occlusion alloy to an external device such as a fuel cell, the hydrogen occlusion alloy is made by flowing a heat medium through a circulation pipe in the hydrogen occlusion alloy. Is heated to release hydrogen (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 5-18261

  However, in the path through which the heat medium flows, most of the heat of the heat medium is easily lost to the hydrogen storage alloy near the heat medium inlet, and heat exchange with the hydrogen storage alloy arranged near the heat medium outlet is insufficient. As a result, the hydrogen release amount that can be released by the entire tank is reduced.

  As described above, when the hydrogen storage alloy is charged (occluded) or released with hydrogen, an exothermic reaction and an endothermic reaction are involved, respectively. Therefore, the hydrogen storage alloy that contributes to the storage and release of hydrogen at the time of hydrogen charging and hydrogen discharging. It is important that an efficient heat exchange is performed on the whole. Conventionally, hydrogen storage / release performance has been improved by examining the flow rate of heat exchangers and heating media, etc., but depending on these studies, the complexity and size of heat exchangers, The increase in efficiency is caused.

  The present invention has been made in view of the above, and temperature changes in the flow path of the heat medium that exchanges heat with the hydrogen storage alloy (decrease in heat medium temperature when releasing hydrogen and heat medium temperature during storage) It is an object of the present invention to provide a hydrogen storage tank that prevents a decrease in the hydrogen storage / release rate and the hydrogen storage / release amount accompanying the increase in

In order to achieve the above object, the hydrogen storage tank of the present invention has a plurality of hydrogen storage alloys having different equilibrium pressures and an arrangement interval between the hydrogen storage alloys on the lower equilibrium pressure side of the plurality of hydrogen storage alloys. A heat medium having heat exchange fins arranged on the tube wall so as to be narrower than the arrangement interval in the hydrogen storage alloy on the higher equilibrium pressure side, and capable of exchanging heat with the hydrogen storage alloy through circulation of the heat medium The plurality of hydrogen storage alloys are arranged such that the respective equilibrium pressures are increased from one end side to the other end side of the heat medium tube, and the hydrogen storage alloy is heated. Is configured such that the heat medium flows through the heat medium pipe from a low equilibrium pressure side to a high side.

  In the hydrogen storage tank of the present invention, a plurality of hydrogen storage alloys having different equilibrium pressures (hereinafter sometimes abbreviated as “MH”) are circulated through a heat medium that can exchange heat with MH. When the hydrogen storage alloy is heated, the heat medium is circulated through the heat medium pipe from the low equilibrium pressure side to the high side (that is, in the heat medium flow direction). By increasing the equilibrium pressure of each MH from the upstream side toward the downstream side), at the time of hydrogen release, the temperature of the heat medium gradually decreases with the flow distance as in the conventional case, and the heat medium pipe in which the hydrogen release rate becomes worse (For example, in the middle to downstream side) In order to keep the hydrogen release in the vicinity, the hydrogen release reaction is performed in response to the temperature of the heat medium that has been lowered due to the increased circulation distance. The release reaction of occluded hydrogen proceeds more easily, It is possible to improve the output rate and the amount of desorbed hydrogen.

  The heating medium in the present invention is a fluid for transferring heat by heat exchange with the MH in order to control the hydrogen storage alloy (MH) to a desired temperature. Also called heat medium.

  In the hydrogen storage tank of the present invention, when the hydrogen is released, the heat medium is circulated from the low MH equilibrium pressure side to the high side, and the hydrogen storage alloy is cooled. The heat medium can be circulated in the direction from the higher equilibrium pressure toward the lower side.

  Contrary to the time when hydrogen is released, the equilibrium pressure is increased from the higher MH equilibrium pressure side to the lower side, that is, from the upstream side to the downstream side in the heat medium flow direction of the heat medium pipe through which the heat medium flows. By arranging the MH so as to be small, the hydrogen occlusion reaction at each MH corresponds to the circulation distance of the heat medium that circulates when occluding hydrogen, that is, the heat medium temperature that increases with the circulation distance. As a result, the hydrogen occlusion reaction easily proceeds in the entire hydrogen occlusion alloy accommodated in the tank, and the occlusion speed and occlusion amount of hydrogen can be improved.

  Further, when the equilibrium pressure (plateau pressure) of the hydrogen storage alloy is lower than the intended working pressure, the hydrogen storage alloy is placed in the direction of the MH equilibrium pressure from the higher side to the lower side. It is possible to distribute a heating medium that heats.

  When it is difficult to sufficiently heat the hydrogen storage alloy in a low temperature environment, the hydrogen storage alloy (MH) having a high equilibrium pressure is preferentially heated so that the hydrogen release reaction can be achieved even in a relatively low temperature environment. It is possible to promote the hydrogen release in the MH that is easy to proceed and to secure the amount of hydrogen that can be supplied externally.

In the hydrogen storage tank of the present invention, heat exchange fins are provided on the wall of the heat medium pipe that exchanges heat with the hydrogen storage alloy. In the present invention, by arranging a plurality of MHs based on the equilibrium pressure as described above, the hydrogen storage / release speed and the amount of release can be improved. Since the exchange efficiency is enhanced, the heat absorption / heat dissipation efficiency during hydrogen release / occlusion, and hence the hydrogen release / occlusion speed and the amount of release / occlusion can be further improved.

Arrangement of the heat exchange fins, the arrangement interval in the hydrogen-absorbing alloy having a low equilibrium pressure side is, that has become narrower than the arrangement interval in the hydrogen-absorbing alloy having a high equilibrium pressure side.

  Among the plurality of MHs, the hydrogen storage alloy having a lower equilibrium pressure has a large temperature change due to heat absorption during hydrogen release and heat generation during hydrogen storage. The heat exchange efficiency can be improved by narrowing the heat exchange fin arrangement interval (fin pitch) than the region where the heat sink is relatively high. In the present invention, the heat absorption efficiency at the time of hydrogen release and the heat dissipation efficiency at the time of hydrogen storage, and thus hydrogen The release rate and release amount of hydrogen, and the storage rate and storage amount of hydrogen can be further improved.

  In the present invention, hydrogen storage alloys (MH) having a plurality of different equilibrium pressures are arranged at appropriate positions in the tank, so that the supplied hydrogen can be stored (filled) / released (storage / release speed and storage / release amount). Is drastically improved, and is effective in building a hydrogen usage system.

  According to the present invention, accompanying a temperature change in the flow path of the heat medium that exchanges heat with the hydrogen storage alloy (a decrease in the heat medium temperature when releasing hydrogen and an increase in the heat medium temperature during storage). It is possible to provide a hydrogen storage tank that prevents a decrease in hydrogen storage / release rate and hydrogen storage / release amount.

  Hereinafter, embodiments of the hydrogen storage tank of the present invention will be described with reference to FIGS. In the hydrogen storage tank of this embodiment, three types of hydrogen storage alloys (MH) having different equilibrium pressures are arranged so that the equilibrium pressure becomes higher along the flow direction of the heat medium that heats MH, and the equilibrium pressure is higher. Accordingly, the heat exchange fins are provided so that the fin pitch becomes wider.

  In the present embodiment, three kinds of hydrogen storage alloys having different equilibrium pressures of 1 MPa, 4 MPa, and 8 MPa are accommodated in a tank, and LLC (Long Life Coolant) is used as a heat medium that exchanges heat with these hydrogen storage alloys. The case where (Liquid that can be used for a long time)] is used will be mainly described. However, the present invention is not limited to the following embodiment.

As shown in FIGS. 1 and 2, the hydrogen storage tank of the present embodiment includes a hydrogen supply / discharge port for supplying and discharging hydrogen, and has a high-pressure tank 11 having a circular cross section and pressure resistance, and is accommodated in the high-pressure tank 11. Heat exchange can be performed between the hydrogen storage alloys Ti ₂₀ Cr ₄₅ V ₃₅ alloy MH1, Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy MH2, and Ti ₃₀ Cr ₄₅ V ₁₀ Mo ₁₅ alloy MH3. In this way, a heat exchange pipe 12 that is a heat medium pipe embedded in the hydrogen storage alloy is provided.

  As shown in FIG. 1, the high-pressure tank 11 is a hollow body formed of a stainless steel alloy (SUS316L) with a circular cross-section and closed at both ends in the length direction of the cylinder, and has a pressure resistance of 35 MPa. Have. As the wall thickness, cross-sectional shape, size, and the like, any thickness, rectangle, ellipse, and other shapes other than those described above can be selected according to the purpose and the like. As the material of the tank, an aluminum alloy, a structure in which an aluminum alloy hollow liner and a carbon fiber reinforced resin are combined can be selected.

  A hydrogen supply / discharge port 13 is formed at one end in the longitudinal direction of the high-pressure tank 11, and a hydrogen supply / discharge tube (not shown) for supplying and discharging hydrogen is connected to the hydrogen supply / discharge port 13. When hydrogen is supplied into the tank through the hydrogen supply / discharge pipe, the supplied hydrogen is stored in the hydrogen storage alloy (MH1, MH2, and MH3) in the high-pressure tank 11 and stored outside. When there is a request for hydrogen from a provided hydrogen using device (not shown), the stored hydrogen can be supplied to the hydrogen using device through a hydrogen supply / discharge pipe.

  An LLC supply / exhaust port (heat medium supply / exhaust port) is formed at the other end of the high-pressure tank 11, and a heat exchange pipe 12 is attached to the LLC supply / exhaust port. The LLC supplied from the outside of the tank through the heat exchange pipe 12 can exchange heat with each MH while flowing through the pipe embedded in the MH in the hydrogen storage tank.

  The heat exchange tube 12 is a U-shaped aluminum tube having a circular cross section, and an LLC (heat medium) supplied from one end of the aluminum tube (hereinafter also referred to as a heat medium supply end) is connected to the other end (hereinafter referred to as a heat medium). It is configured so that the LLC can be circulated by a circulation system (not shown) constructed by being connected to the heat medium supply end of the aluminum tube and the heat medium discharge end.

  As shown in FIG. 2, aluminum heat exchange fins 15A, 15B, and 15C are attached to the outer wall of the heat exchange pipe 12 at predetermined intervals (fin pitch) as shown in FIG. MH enters between the fins so that heat can be exchanged with MH quickly and efficiently.

The fins 15A are arranged at equal intervals in the fin pitch a in the Ti ₂₀ Cr ₄₅ V ₃₅ alloy MH1, and the fins 15B are arranged at equal intervals in the fin pitch b in the Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy MH2. The fins 15C are arranged at equal intervals with the fin pitch c in the Ti ₃₀ Cr ₄₅ V ₁₀ Mo ₁₅ alloy MH3. Each fin pitch has a relationship of a <b <c, and when the hydrogen is released, the heat absorption amount is large, and when the hydrogen is occluded, the heat generation amount is large. That is, many fins are attached to the heat exchange pipe located in the MH having a low equilibrium pressure. The heat exchange efficiency is further improved.

  In this embodiment, three kinds of MH regions having different equilibrium pressures are provided along the heat exchange tube in the order of the equilibrium pressures, so that the hydrogen occlusion, release speed, and hydrogen occlusion / release amount can be improved. However, by narrowing the fin pitch in accordance with the MH equilibrium pressure as described above, it is possible to further improve the hydrogen storage / release speed and the hydrogen storage / release amount.

As shown in FIG. 2, as shown in FIG. 2, the high pressure tank 11 has an equilibrium pressure along the LLC flow path from the heat medium supply end of the heat exchange pipe 12 toward the heat medium discharge end as a hydrogen storage alloy (MH). Ti ₂₀ Cr ₄₅ V ₃₅ alloy MH1 with an equilibrium pressure of 1 MPa, Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy MH2 with an equilibrium pressure of 4 MPa, and an arrangement order that increases with P ^MH1 <P ^MH2 <P ^MH3 (under the same temperature), and A Ti ₃₀ Cr ₄₅ V ₁₀ Mo ₁₅ alloy MH3 having an equilibrium pressure of 8 MPa is accommodated.

  Three types of MH, MH1, MH2 and MH3 can store and store hydrogen when hydrogen is supplied from the outside through a hydrogen supply / exhaust port, and can be heated or reduced in tank pressure as necessary. Sometimes, the hydrogen stored in MH dissociates, and the stored hydrogen can be released to the outside and supplied to a hydrogen-using device such as a fuel cell. Specifically, hydrogen is occluded and discharged as follows.

In this embodiment, by arranging three types of MH so that the equilibrium pressure of each MH increases in the order of MH1 <MH2 <MH3 (under the same temperature) along the LLC flow direction as a heat medium, when released to the outside, LLC temperature T ¹ is as heating medium is supplied to the heat exchange tubes 12, the supplied LLC first exchanging heat between the MH1, heat is applied to the lowest equilibrium pressure MH1 When released, hydrogen is released from MH1. After that, the LLC at the temperature T ² (<T ¹ ), which has decreased in temperature due to heat exchange with MH1, reaches the MH2 through the heat exchange pipe 12, and exchanges heat with the MH2 to equilibrate next to the MH1. When heat is applied to the low-pressure MH2, hydrogen is released from the MH2. MH2 temperature ^T 3 which further temperature drop in the heat exchanger ^{(<T 2)} of the LLC reached MH3, MH3 is hydrogen it is relatively heat cold temperature ^{T 3} is provided for the equilibrium pressure is the highest Release is possible.

  In general, hydrogen storage alloys tend to release hydrogen when the equilibrium pressure is high. Therefore, reducing the equilibrium pressure increases the amount of hydrogen that can be stored (stored) relatively stably, but releases the stored hydrogen. Although it becomes difficult, by selecting MH with different equilibrium pressure according to the temperature change of the heating medium responsible for MH temperature control as in this embodiment, the hydrogen occlusion / release property and the amount of hydrogen occluded / released can be reduced. It is possible to increase.

That is, in the conventional configuration using one type of MH, the temperature drops from the temperature _TH to the temperature _TL in the process in which the LLC flows from the heat medium supply end to the heat medium discharge end of the heat exchange pipe 12. However, since the MH equilibrium pressure also decreases with this temperature decrease, the pressure difference between the equilibrium pressure and the lower limit pressure (for example, the fuel cell operating lower limit pressure) required for a hydrogen-using device such as a fuel cell. Cannot be maintained sufficiently. In the present embodiment, MH2 having a higher equilibrium pressure even if the LLC temperature gradually decreases with circulation by arranging MH in the order of the equilibrium pressure along the heat exchange pipe for performing heat exchange as described above, MH3 can maintain a pressure difference. That is, as shown in FIG. 3, when the LLC temperature is T _H , MH1 satisfies the desired equilibrium pressure (that is, hydrogen releasing property; the same applies hereinafter), but when the LLC temperature subsequently decreases, T _M (<T _H ) The desired equilibrium pressure that cannot be obtained by lowering the equilibrium pressure of MH1 is mainly maintained by MH2, and the desired equilibrium pressure that cannot be obtained by lowering the equilibrium pressure of MH1 and MH2 by MH3 mainly at T _L (<T _M ). keep.
As described above, the hydrogen release rate, and hence the hydrogen release amount, can be improved.

Further, at the time of hydrogen filling, the arrangement structure of MH1 / MH2 / MH3 is maintained, and the direction opposite to the flow direction of the LLC (heat medium) at the temperature T ¹ (from the heat medium discharge end of the heat exchange pipe 12 to the heat medium supply end). In the direction of) to supply and circulate LLC at a temperature t ¹ as a cooling heat medium. At this time, the equilibrium pressure of MH decreases along the flow path of the heat medium (LLC) in the heat exchange pipe 12 (MH3>MH2>MH1; under the same temperature).

That is, in the configuration using one type of MH as in the prior art, the temperature rises from the temperature t _L to the temperature t _H while the LLC flows from the heat medium discharge end of the heat exchange pipe 12 toward the heat medium supply end. As the temperature rises, the equilibrium pressure of MH also rises. Therefore, as the LLC approaches the heat medium supply end from which the LLC is discharged, the pressure difference between the filling pressure and the equilibrium pressure decreases, and the filling speed decreases. In the present embodiment, the MH2 having a higher equilibrium pressure even when the LLC temperature gradually increases with the flow by arranging the MH in the order of the equilibrium pressure of the MH along the heat exchange pipe for performing heat exchange as described above. , MH3 can keep the pressure difference. That is, as shown in FIG. 4, when the LLC temperature is _TL , MH3 shows a desired filling capacity (that is, hydrogen storage ability; the same applies hereinafter), but when the LLC temperature rises thereafter, T _M (> T _L ) Mainly due to MH2, the desired filling capacity that cannot be obtained by increasing the equilibrium pressure of MH3 is maintained, and at T _H (> T _M ), the desired filling capacity that cannot be obtained by mainly increasing the equilibrium pressure of MH3 and MH2 by MH1. keep.
As described above, it is possible to improve the hydrogen storage speed, and hence the hydrogen storage amount.

In the hydrogen storage tank of this embodiment, when hydrogen is to be externally supplied in a low temperature environment, the equilibrium pressure (plateau pressure) of the hydrogen storage alloy is lower than the pressure P when the tank is used, which is the intended use pressure. When the temperature range is reached, the arrangement structure of MH1 / MH2 / MH3 is maintained, and the direction opposite to the flow direction of the LLC (heat medium) at the temperature T ¹ (the heat medium supply from the heat medium discharge end of the heat exchange pipe 12) In the direction toward the end), LLC of temperature Ta is supplied as ^a heating medium for heating and distributed. At this time, the equilibrium pressure of MH decreases from the higher equilibrium pressure toward the lower side along the flow path of the heat transfer medium (LLC) of the heat exchange pipe 12 (MH3) as in the case of hydrogen filling (occlusion). >MH2>MH1; under the same temperature).

For example, when starting a fuel cell (FC) in a low-temperature environment, an LLC that heats MH from the high MH side of the equilibrium pressure toward the low MH side flows until the FC is warmed up. By applying heat from the MH3 side so that hydrogen is preferentially released from the highest MH3, it is possible to ensure the hydrogen release rate and amount in a low temperature environment.
When the FC is warmed up to such an extent that hot water can be supplied into the tank, the flow direction of the LLC is further reversed in order to perform steady hydrogen release, and the heating medium supply of the heat exchange tube 12 is performed in the same manner as in the above hydrogen release. The LLC is circulated from the end toward the heat medium discharge end.

  Here, the temperature range in which the equilibrium pressure (plateau pressure) of the hydrogen storage alloy is lower than the pressure P when the tank is used is the use pressure in the operating state where the equilibrium pressure of MH stores or releases hydrogen due to a decrease in the environmental temperature. Is a temperature range in which the occlusion and release of hydrogen are reduced or become impossible when the pressure P falls below a predetermined pressure P set in advance.

That is, since the equilibrium pressure of MH also decreases in a low-temperature environment, the pressure difference between the equilibrium pressure (filling pressure) and the lower limit pressure becomes smaller in the configuration using one type of MH as in the past, and the hydrogen release rate and Although the discharge amount is also reduced, in this embodiment, by using three types of MH having different equilibrium pressures as described above, the pressure difference can be maintained between MH3 and MH2 having higher equilibrium pressures. Three kinds of MH are arranged in the order of the equilibrium pressure along the heat exchange pipe, and the MH equilibrium pressure is circulated through the LLC that heats the MH from the MH3 side having the highest equilibrium pressure, so that the MH equilibrium pressure is in the intended use state. Even under a low temperature environment where the pressure P is lower than the hydrogen pressure P, the hydrogen release rate and amount can be secured. That is, as shown in FIG. 5, when the MH temperature is high (> T _M ), a certain amount of equilibrium pressure (that is, hydrogen storage ability; the same applies hereinafter) can be obtained only with MH1, but as the MH temperature decreases (< T _M ) MH1 alone does not maintain a pressure difference, and therefore, particularly in a low temperature environment, mainly MH3 and MH2 maintain a desired equilibrium pressure (filling pressure) that cannot be obtained because the equilibrium pressure of MH1 decreases.
As described above, it is possible to improve the hydrogen release rate in a low temperature environment, and hence the hydrogen release amount.

  Examples of the hydrogen storage alloy (MH) include binary alloys, ternary alloys, quaternary alloys, and the like, for example, TiCrV alloys, TiCrMn alloys, LaNi alloys, TiFe alloys, TiVMo alloys. , TiCrVNi alloy, TiCrMoV alloy, etc., can be appropriately selected in consideration of the equilibrium pressure.

Specific examples of the _{MH, LaNi 5, Ti 25 Cr} 50 V 25, Ti 25 Cr 25 V 50, Ti 36 Cr 32 Mn 32, Ti 30 Cr 35 Mn 35, Ti 20 Cr 45 V 35, Ti 30 Cr 45 V _{10 Mo 15, Ti 25 Cr 50} V 20 Mo 5, Ti 25 Cr 44 V 25 Fe 6, Ti 25 Cr 50 V 20 Ni 5, such as _{Ti 11 Cr 12 V 71 Mo 5} Ni 1 can be mentioned.

As a combination of a plurality of hydrogen storage alloys, for example, (1) a hydrogen storage alloy having an equilibrium pressure of 1 × 10 ^{−1 to} 7 × 10 ⁻¹ MPa at 50 to 80 ° C. (for example, Ti ₂₀ Cr ₄₅ V ₃₅ alloy) ), (2) a hydrogen storage alloy (for example, Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy) having an equilibrium pressure at 10 to 30 ° C. of 0.8 × 10 ^{−1 to} 7 × 10 ⁻¹ MPa, and (3) — 30-10 equilibrium pressure at ℃ is ^{0.2 × 10 -1 ~4 × 10 -1} MPa hydrogen storage alloy _{(e.g., Ti 30 Cr 45 V 10 Mo} 15 alloy) is selected from, different equilibrium pressure Two or three or more combinations are preferred.
As a specific example, in addition to the three combinations of the present embodiment, for example, a combination of Ti ₂₀ Cr ₄₅ V ₃₅ and Ti ₃₀ Cr ₄₅ V ₁₀ Mo ₁₅ , Ti ₂₀ Cr ₄₅ V ₃₅ and Ti ₂₅ Cr _{50 are used.} A combination with V ₂₅ and a combination of Ti ₂₀ Cr ₄₅ V ₃₅ , Ti ₃₀ Cr ₃₅ Mn ₃₅ and Ti ₂₅ Cr ₅₀ V ₂₅ can be preferably exemplified.

The form of the hydrogen storage alloy (MH) may be any shape and size such as powder, granule, and pellet.
For the hydrogen storage alloy, for example, the metal powder is arc-melted so as to have a desired composition and composition ratio to obtain a crude alloy (preferably further annealed), and this is pulverized using a pulverizer such as a ball mill. The hydrogen storage tank of the present invention can be produced by filling the tank with MH such as the obtained powdery substance (preferably at a high density).

  In this embodiment, the case where LLC is used as the heat medium that exchanges heat with MH has been described. However, various substances other than LLC can be used, and (1) the pressure that can be used is appropriate. Yes, (2) Large heat capacity or latent heat per unit volume, large heat transfer coefficient, (3) Does not corrode equipment, (4) Non-flammable, inexpensive, non-toxic, etc. It can be selected according to the purpose from the features such as. Other than LLC, for example, a liquid such as oil or water can be used.

In the above embodiment, the distance (tube length) of the heat exchange pipe located in the MH1 having the lowest equilibrium pressure is increased, and the length of the pipe in the MH1 is increased so that hydrogen is absorbed and released in the MH1. And increasing the storage / release performance in the region where the temperature is likely to be low in the middle to downstream of the heat exchange pipe (the MH1 tends to decrease the storage / release performance), and the hydrogen storage / release speed, The amount of occlusion / release of hydrogen can be further improved.
In addition to the MH configuration of the present embodiment, the shape and size of the MH in which a plurality of types are arranged may be selected according to the equilibrium pressure, the internal structure, the use environment, and the like.

In the above description, the case where three types of MH having different equilibrium pressures are used as the plurality of MHs has been described. However, two types of MH having different equilibrium pressures are used to move from the heat medium supply end side toward the heat medium discharge end side. A configuration may be adopted in which MH is arranged so that the equilibrium pressure is increased, or a configuration using four or more MHs having different equilibrium pressures may be employed.
Further, the MH of the equilibrium pressure P ^{α and} the MH of the equilibrium pressure P ^β (P ^α <P ^β ), and the MH (P ^α <P ^γ <P ^β ) of the equilibrium pressure P ^γ composed of a mixture of these two types of MH, You may make it comprise using.

It is a perspective view of the hydrogen storage tank concerning the embodiment of the present invention. It is a schematic sectional drawing which shows the internal structure of the hydrogen storage tank which concerns on embodiment of this invention. It is a relationship figure which shows the relationship between the temperature of MH and the equilibrium pressure at the time of hydrogen discharge | release. It is a relationship figure which shows the relationship between the temperature of MH at the time of hydrogen occlusion, and an equilibrium pressure. It is a relationship figure which shows the relationship between the temperature of MH in a low temperature environment, and an equilibrium pressure.

Explanation of symbols

12 ... heat exchange tubes 15A, 15B, 15C ... fins _MH1 ... Ti _{20 Cr} 45 _{V 35} alloy _MH2 ... _{Ti 36} Cr _{32 Mn} 32 alloy _{MH3 ... Ti 30 Cr 45 V 10} Mo 15 alloy

Claims (4)

A plurality of hydrogen storage alloys having different equilibrium pressures;
Heat exchange fins arranged such that the arrangement interval in the hydrogen storage alloy on the lower equilibrium pressure side among the plurality of hydrogen storage alloys is narrower than the arrangement interval in the hydrogen storage alloy on the higher equilibrium pressure side It has a wall, comprising a hydrogen absorbing alloy heat exchangeable heat transfer tube heat medium to flow, and
The plurality of hydrogen storage alloys are arranged such that the respective equilibrium pressures increase from one end side to the other end side of the heat medium pipe, and when the hydrogen storage alloy is heated, The hydrogen storage tank which distribute | circulates to the said heat-medium pipe | tube from the side where the said equilibrium pressure is low to the high side.   2. The hydrogen storage tank according to claim 1, wherein, when the hydrogen storage alloy is cooled, the heat medium pipe circulates the heat medium from a high equilibrium pressure side to a low side.   The heat medium pipe circulates the heat medium from a higher side of the equilibrium pressure to a lower side when the equilibrium pressure of the hydrogen storage alloy is lower than an intended working pressure. Item 3. The hydrogen storage tank according to Item 1 or 2. The plurality of hydrogen storage alloys have an equilibrium pressure at 50 to 80 ° C. of 1 × 10 ^{−1 to} 7 × 10 ⁻¹ MPa, and an equilibrium pressure at 10 to 30 ° C. of 0.8 × 10 ^−1. different ~7 × ¹⁰ -1 MPa of hydrogen-absorbing alloy, and the equilibrium pressure at -30 to-10 ° C. is the equilibrium pressure is selected from ^{0.2 × 10 -1 ~4 × 10 -1} MPa of hydrogen storage alloy The hydrogen storage tank of any one of Claims 1-3 containing 2 or more types .

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