Fuel cell system

Abstract

Provided is a fuel cell system including: a fuel cell; a tank body in which a hydrogen storage alloy that adsorbs and releases hydrogen is housed, and that supplies hydrogen to the fuel cell; and a holding body that houses the tank body detachably. The fuel cell system is configured to heat the tank body using waste heat of the fuel cell. The tank body is formed of aluminum or an aluminum alloy. A first aluminum anodized layer is formed on an outer surface of the tank body.

Description

Technical Field

[0001] This disclosure relates to fuel cell systems. Background Technology

[0002] Fuel cell systems are known to utilize the waste heat from fuel cells to heat a tank containing a hydrogen storage alloy that supplies hydrogen to the fuel cell. The fuel cell system includes a retainer for detachably storing the tank.

[0003] When the hydrogen storage alloy releases hydrogen, its temperature decreases due to an endothermic reaction. If the temperature of the hydrogen storage alloy decreases, the amount of hydrogen released, i.e., the amount of hydrogen supplied to the fuel cell, will decrease.

[0004] The electric wheelchair described in Japanese Patent Application Publication No. 2007-45301 includes a fuel cell body, a hydrogen cylinder with a built-in hydrogen storage alloy, and a cylinder holding member for detachably storing the hydrogen cylinder. In this electric wheelchair, gas heated by the waste heat of the fuel cell body is guided through a gas guide to the space between the inner surface of the cylinder holding member and the outer surface of the hydrogen cylinder. This heats the hydrogen cylinder, thus suppressing any decrease in the amount of hydrogen supplied to the fuel cell body. Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] When assembling or disassembling the tank relative to the retainer, damage to the tank may occur due to contact between the tank and the retainer. Therefore, it is considered to protect the outer surface of the tank by forming a coating with a resin coating. However, in this case, the thermal conductivity of the outer surface of the tank is reduced due to the coating, which may lead to a decrease in the heating efficiency of heating the tank based on waste heat from the fuel cell. Therefore, it is desirable to balance the protection of the outer surface of the tank with the suppression of the reduction in the thermal conductivity of the tank.

[0007] Solution for solving the problem

[0008] A fuel cell system for solving the above-mentioned problems includes: a fuel cell; a tank containing a hydrogen storage alloy for adsorbing and releasing hydrogen, supplying hydrogen to the fuel cell; and a retainer for detachably storing the tank. The fuel cell system is configured to use waste heat from the fuel cell to heat the tank, wherein the tank is formed of aluminum or an aluminum alloy, and an aluminum anodized layer is formed on the outer surface of the tank. Attached Figure Description

[0009] Figure 1 This is a simplified structural diagram illustrating one embodiment of a fuel cell system.

[0010] Figure 2 It means Figure 1 A cross-sectional view of the internal flow path of the retainer. Detailed Implementation

[0011] The following is for reference Figure 1 and Figure 2 One embodiment of the fuel cell system will be described.

[0012] (Structure of fuel cell system 10)

[0013] like Figure 1 As shown, the fuel cell system 10 includes a fuel cell 20, a tank 30, a retainer 40, a compressor 60, and a pump 61.

[0014] The fuel cell 20 supplies electricity to an external load 70. The external load 70 is, for example, a motor driven by electricity. The tank 30 supplies fuel gas to the fuel cell 20. The tank 30 is detachably housed in a retainer 40. The compressor 60 supplies oxidant gas to the fuel cell 20. The pump 61 supplies coolant C, such as water, to the fuel cell 20. Coolant C is an example of a "heat medium".

[0015] (Structure of fuel cell 20)

[0016] The fuel cell 20 has a fuel gas supply port 21 for supplying fuel gas, a fuel gas outlet 22 for discharging fuel gas, an oxidant gas supply port 23 for supplying oxidant gas, and an oxidant gas outlet 24 for discharging oxidant gas. The fuel gas supply port 21 is connected to the tank 30 via a first gas pipe 11. The oxidant gas supply port 23 is connected to the compressor 60 via a second gas pipe 12.

[0017] The fuel cell 20 is, for example, a solid polymer fuel cell with a power generation section 25, wherein the power generation section 25 includes a membrane electrode assembly (not shown). The power generation section 25 is disposed in the central part of the fuel cell 20. Fuel gas supplied from the fuel gas supply port 21 passes through the power generation section 25 and is discharged to the outside of the fuel cell 20 from the fuel gas outlet 22. Oxidant gas supplied from the oxidant gas supply port 23 passes through the power generation section 25 and is discharged to the outside of the fuel cell 20 from the oxidant gas outlet 24. In the power generation section 25, electricity is generated by an electrochemical reaction between the fuel gas and the oxidant gas. The fuel gas is, for example, hydrogen. The oxidant gas is, for example, air.

[0018] The fuel cell 20 has a coolant supply port 26 for supplying coolant C and a coolant outlet 27 for discharging coolant C. The coolant C flows inside the fuel cell 20, thereby cooling the fuel cell 20 which generates heat during power generation by the power generation unit 25.

[0019] (Structure of tank 30)

[0020] The tank body 30 is a cylindrical container with an internal space. The tank body 30 is made of aluminum or an aluminum alloy.

[0021] A hydrogen storage alloy for adsorbing and releasing hydrogen is built into the tank 30. A hydrogen outlet 31 is provided at one end of the tank 30 along its length. A first gas pipe 11 is connected to the outlet 31. The hydrogen released from the hydrogen storage alloy by the tank 30 is supplied to the fuel cell 20 through the first gas pipe 11.

[0022] When the hydrogen storage alloy releases hydrogen, its temperature decreases due to an endothermic reaction. If the temperature of the hydrogen storage alloy decreases, the pressure inside the tank 30 decreases, thereby reducing the amount of hydrogen released. In this embodiment, the temperature decrease of the hydrogen storage alloy is suppressed by circulating the coolant C in the circulation path between the fuel cell 20 and the holder 40.

[0023] like Figure 2 As shown, a first aluminum anodized layer 30a is formed all over the outer surface, more specifically, the outer circumference of the tank body 30. The first aluminum anodized layer 30a is an anodized coating formed on the outer surface of the tank body 30 by anodizing aluminum. The thermal conductivity of the first aluminum anodized layer 30a is lower than that of the substrate of the tank body 30, which is made of aluminum or aluminum alloy.

[0024] (Maintain the structure of body 40)

[0025] The retainer 40 is a cylindrical shape with its upper end closed. The canister 30 is housed in the retainer 40 such that the nozzle 31 points downward. The retainer 40 has a cylindrical peripheral wall 41 that holds the outer peripheral surface of the canister 30.

[0026] The retainer 40 comprises a cylindrical inner cylinder 42, a cylindrical outer cylinder 43, and a lid 45. The inner cylinder 42 houses the can 30. The outer cylinder 43 houses the inner cylinder 42. The lid 45 covers the upper end of the can 30 and is installed on the upper end of the outer cylinder 43. The peripheral wall 41 of the retainer 40 is composed of the separable inner cylinder 42 and outer cylinder 43. The inner cylinder 42, outer cylinder 43, and lid 45 are made of aluminum or an aluminum alloy.

[0027] The inner circumferential surface of the inner cylinder 42 is in contact with the outer circumferential surface of the tank body 30 all around its circumference. The upper end of the tank body 30 protrudes from the upper opening of the inner cylinder 42.

[0028] A male thread is formed all around the circumference of the upper end of the outer cylinder 43 (illustration omitted). A first gas pipe 11 for connection to the nozzle 31 is provided at the lower end of the outer cylinder 43 (see figure). Figure 1 The outlet 44 is led out. The outlet 44 is connected to the lower opening of the inner cylinder 42.

[0029] The cover 45 is domed. A female thread (not shown) is formed on the inner circumferential surface of the cover 45, which engages with the male thread of the outer cylinder 43. The cover 45 is installed on the outer cylinder 43 in a detachable manner by engaging the female thread of the cover 45 with the male thread of the outer cylinder 43.

[0030] A substrate made of aluminum or aluminum alloy is exposed on the inner surface of the retainer 40, more specifically the inner surface of the inner cylinder 42 and the inner surface of the cover 45. The substrate includes an aluminum or aluminum alloy base and an oxide coating that naturally forms on the surface of the base by combining with oxygen in the air. The inner circumference of the inner cylinder 42, where the substrate is exposed, is in contact with the first aluminum anodized layer 30a all around its circumference.

[0031] (Structure of internal flow path 46)

[0032] The peripheral wall 41 has an internal flow path 46 extending along the axial direction of the peripheral wall 41. The internal flow path 46 includes a cylindrical space disposed throughout the entire circumference of the interior of the peripheral wall 41. By housing the inner cylinder 42 within the outer cylinder 43, the internal flow path 46 is formed between the outer circumferential surface of the inner cylinder 42 and the inner circumferential surface of the outer cylinder 43. The upper end of the internal flow path 46 is sealed by a first sealing ring 51 disposed between the outer circumferential surface of the inner cylinder 42 and the inner circumferential surface of the outer cylinder 43. The lower end of the internal flow path 46 is sealed by a second sealing ring 52 disposed between the outer circumferential surface of the inner cylinder 42 and the inner circumferential surface of the outer cylinder 43.

[0033] A second aluminum anodized layer 40a is formed on the inner surface of the internal flow path 46. The second aluminum anodized layer 40a is an anodized coating formed on the inner surface of the internal flow path 46 by aluminum anodizing treatment. The second aluminum anodized layer 40a is formed on the entire outer surface of the inner cylinder 42 constituting the internal flow path 46 and on the entire inner surface of the outer cylinder 43 constituting the internal flow path 46.

[0034] The internal flow path 46 has an inlet 47 and an outlet 48. The inlet 47 and the outlet 48 extend through the outer cylinder 43 along the thickness direction. The inlet 47 is located in the peripheral wall 41 at a position above the outlet 48.

[0035] like Figure 1 As shown, inlet 47 is connected to coolant outlet 27 via first cooling pipe 13. Inlet 47 introduces coolant C discharged from coolant outlet 27 into internal flow path 46. Outlet 48 is connected to coolant supply port 26 via second cooling pipe 14. Outlet 48 discharges coolant C from internal flow path 46 to coolant supply port 26. Pump 61 is installed midway through second cooling pipe 14 to direct coolant C toward coolant supply port 26.

[0036] Coolant C circulates in the circulation path. The circulation path includes: the interior of the fuel cell 20, including the coolant supply port 26 and the coolant outlet 27; a first cooling pipe 13; an internal flow path 46 of the retainer 40; and a second cooling pipe 14.

[0037] Coolant C flows inside fuel cell 20, thereby cooling the fuel cell 20 which generates heat during power generation. During this time, the temperature of coolant C rises due to heat exchange between coolant C and fuel cell 20. The cooled coolant C, after being discharged from coolant outlet 27, is introduced into internal flow path 46 of holder 40 via inlet 47. The flow of coolant C through internal flow path 46 heats the tank 30, which cools as hydrogen is released from the hydrogen storage alloy, via holder 40. During this time, the temperature of coolant C decreases due to heat exchange between coolant C and holder 40. The cooled coolant C is then discharged into coolant supply port 26 of fuel cell 20 via outlet 48. Thus, fuel cell 20 is cooled.

[0038] In the fuel cell system 10, coolant C flows through the internal flow path 46, thereby heating the tank 30 by exchanging heat with the waste heat of the fuel cell 20. This suppresses the temperature drop of the tank 30, and consequently suppresses the temperature drop of the hydrogen storage alloy. Consequently, it suppresses the reduction in the amount of hydrogen released from the hydrogen storage alloy, i.e., the reduction in the amount of hydrogen supplied to the fuel cell 20.

[0039] <The function of this implementation method>

[0040] In the fuel cell system 10, a first aluminum anodic oxide layer 30a is formed on the outer surface of the tank 30. This improves the strength of the outer surface of the tank 30. Consequently, damage to the outer surface of the tank 30 can be prevented when the tank 30 is being installed or removed from the retainer 40, such as during tank replacement. Furthermore, compared to forming a coating on the outer surface of the tank 30 using a resin coating, this method helps prevent a decrease in the thermal conductivity of the outer surface of the tank 30 due to surface protection.

[0041] <Effects of this implementation method>

[0042] (1) The fuel cell system 10 includes a fuel cell 20, a tank 30 for supplying hydrogen to the fuel cell 20, and a retainer 40 for detachably storing the tank 30. The fuel cell system 10 uses the waste heat from the fuel cell 20 to heat the tank 30. The tank 30 is made of aluminum or an aluminum alloy. A first aluminum anodic oxide layer 30a is formed on the outer surface of the tank 30.

[0043] Based on the above structure, and especially in fulfilling the above-mentioned functions, it is possible to both protect the outer surface of the tank 30 and suppress the reduction of the thermal conductivity of the tank 30.

[0044] (2) The peripheral wall 41 in contact with the first aluminum anodic oxide layer 30a has an internal flow path 46 for the flow of coolant C for heat exchange with the waste heat of fuel cell 20.

[0045] According to the above structure, since the peripheral wall 41 is in contact with the tank 30 via the first aluminum anodized layer 30a, the coolant C flowing in the internal flow path 46 exchanges heat with the tank 30 via the peripheral wall 41. Therefore, the heat exchange efficiency between the fuel cell 20 and the tank 30 can be improved.

[0046] (3) The aluminum or aluminum alloy substrate is exposed on the inner surface of the peripheral wall 41 that is in contact with the first aluminum anodized layer 30a.

[0047] According to the above structure, compared with the case where a protective layer such as an aluminum anodized layer is formed on the inner surface of the peripheral wall 41, the decrease in the thermal conductivity of the inner surface of the peripheral wall 41 can be suppressed.

[0048] (4) A second aluminum anodic oxide layer 40a is formed on the inner surface of the internal flow path 46.

[0049] To improve the heat exchange efficiency between the coolant C and the tank 30 via the peripheral wall 41, it is preferable that the aluminum or aluminum alloy substrate is exposed on the inner surface of the internal flow path 46. However, in this case, the inner surface of the internal flow path 46 may be corroded due to the coolant C flowing in the internal flow path 46.

[0050] In this respect, according to the above structure, a second aluminum anodized layer 40a is formed on the inner surface of the internal flow path 46. This suppresses corrosion of the inner surface of the internal flow path 46. Furthermore, compared to the case where the aluminum or aluminum alloy substrate is exposed on the inner surface of the internal flow path 46, the thermal conductivity of the inner surface of the internal flow path 46 decreases when the second aluminum anodized layer 40a is formed. However, compared to the case where a coating is formed on the inner surface of the internal flow path 46 using a resin coating, the decrease in the thermal conductivity of the inner surface of the internal flow path 46 due to protection of the inner surface can be suppressed.

[0051] (5) An internal flow path 46 is formed between the outer surface of the inner cylinder 42 and the inner surface of the outer cylinder 43.

[0052] Based on the above structure, by separating the inner cylinder 42 from the outer cylinder 43, the condition of the inner surface of the internal flow path 46 where the second aluminum anodized layer 40a is formed can be easily confirmed. Therefore, the deterioration state of the second aluminum anodized layer 40a can be easily confirmed.

[0053] <Example of Change>

[0054] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other within the scope of technical inconsistency.

[0055] The retainer 40 may also replace the peripheral wall 41 and have piping capable of holding the tank 30 and supplying coolant C. Such piping can be, for example, a spiral piping surrounding the outer peripheral surface of the tank 30.

[0056] The internal flow path 46 does not necessarily have to be cylindrical. The internal flow path 46 also does not necessarily have to be continuous in the circumferential direction of the peripheral wall 41. For example, the cross-sectional shape of the internal flow path 46, which is orthogonal to the axial direction of the peripheral wall 41, can also be C-shaped.

[0057] The second aluminum anodized layer 40a may also be formed only on either the outer surface of the inner cylinder 42 or the inner surface of the outer cylinder 43.

[0058] Alternatively, the second aluminum anodized layer 40a may not be formed on the inner surface of the internal flow path 46.

[0059] The retainer 40 may also not have an internal flow path 46. In this case, the heat medium can simply be supplied directly from inside the retainer 40 to the outer surface of the tank 30.

[0060] Alternatively, an aluminum anodizing layer identical to the first aluminum anodizing layer 30a may be formed on the inner surface of the retainer 40 in the portion that contacts the first aluminum anodizing layer 30a.

[0061] A gap may also be provided between the inner surface of the inner cylinder 42 and the first aluminum anodized layer 30a.

[0062] The heat transfer medium can simply supply waste heat from fuel cell 20 to tank 30, or it can be supplied from tank 30 to fuel cell 20. That is, the heat transfer medium can also be exempted from circulating between fuel cell 20 and tank 30.

[0063] The heat transfer medium can be a liquid different from water, or it can be a gas such as air.

[0064] Alternatively, a first aluminum anodized layer 30a can be formed on the bottom surface of the tank 30, which is part of the outer surface. In this case, the bottom surface of the tank 30 can also contact the inner surface of the cover 45.

[0065] The first aluminum anodic oxide layer 30a can also be formed on the outer surface of the nozzle 31.

[0066] The second aluminum anodized layer 40a can also be formed on the inner circumferential surface of the inlet 47 and the inner circumferential surface of the outlet 48.

Claims

1. A fuel cell system comprising: Fuel cells; The tank body is configured to contain a hydrogen storage alloy for adsorbing and releasing hydrogen, supplying hydrogen to the fuel cell; and A retaining element allows the canister to be detachably stored. The fuel cell system is configured to use the waste heat from the fuel cell to heat the tank, wherein... The tank body is made of aluminum or aluminum alloy. An aluminum anodized layer is formed on the outer surface of the tank.

2. The fuel cell system according to claim 1, wherein, The retainer has a peripheral wall that contacts the aluminum anodized layer. The peripheral wall has an internal flow path, which is configured to allow the flow of a heat medium for heat exchange with the waste heat of the fuel cell.

3. The fuel cell system according to claim 2, wherein, Aluminum or aluminum alloy is exposed on the inner surface of the peripheral wall.

4. The fuel cell system according to claim 2 or 3, wherein, The aluminum anodic oxide layer is the first aluminum anodic oxide layer. The peripheral wall is formed of aluminum or an aluminum alloy. A second aluminum anodic oxide layer is formed on the inner surface of the internal flow path.

5. The fuel cell system according to claim 4, wherein, The peripheral wall has an inner cylinder and an outer cylinder for housing the inner cylinder. The internal flow path is formed between the outer surface of the inner cylinder and the inner surface of the outer cylinder.

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