fuel cell system

Abstract

This invention provides a fuel cell system capable of easily and efficiently preventing the freezing of cooling water. The fuel cell system of one embodiment includes a fuel cell section and comprises: a cooling water circulation system for circulating cooling water through the fuel cell section; a heat exchange system for performing heat exchange between seawater and the cooling water circulating in the cooling water circulation system; and a control unit for controlling the heat exchange. When the temperature associated with the cooling water circulation system is below a first threshold and the temperature of the seawater used for heat exchange in the heat exchange system is above a second threshold higher than the first threshold, the control unit heats the cooling water through the heat exchange.

Description

Technical Field

[0001] Embodiments of the present invention relate to fuel cell systems. Background Technology

[0002] A fuel cell system comprises a fuel cell stack consisting of multiple stacked fuel cell cells. Each fuel cell cell has an electrolyte membrane sandwiched between a fuel electrode and an air electrode. In each fuel cell cell, a fuel electrode gas containing hydrogen is supplied to the fuel electrode, and air is supplied to the air electrode (oxidant electrode), thereby generating electricity through an electrochemical reaction.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-236734 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] Fuel cell systems are sometimes used as power sources in ships moving at sea. These systems are, for example, installed on the ship's deck. In such cases, when the ambient temperature drops and the fuel cell stops, the cooling water used to cool it may freeze.

[0008] In the past, methods such as heating the cooling water with heaters were used to prevent it from freezing. However, this method consumed a lot of electricity and required a lot of equipment.

[0009] Given the circumstances described above, it has historically been difficult to implement effective and efficient measures to prevent cooling water from freezing.

[0010] Therefore, the technical problem to be solved by the present invention is to provide a fuel cell system that can easily and efficiently prevent the freezing of cooling water.

[0011] Means for solving technical problems

[0012] The fuel cell system of the embodiment includes a fuel cell section and comprises: a cooling water circulation system for circulating cooling water through the fuel cell section; a heat exchange system for performing heat exchange between seawater and the cooling water circulating in the cooling water circulation system; and a control unit for controlling the heat exchange. When the temperature related to the cooling water circulation system is below a first threshold and the temperature of the seawater used in the heat exchange system for heat exchange is above a second threshold higher than the first threshold, the control unit heats the cooling water through heat exchange. Attached Figure Description

[0013] Figure 1This is a schematic diagram showing the overall structure of the fuel cell system according to the first embodiment.

[0014] Figure 2 This is a perspective view schematically showing the overall structure of the fuel cell section in the first embodiment.

[0015] Figure 3 This is a cross-sectional view showing a partial cross-section of the fuel cell section in the first embodiment.

[0016] Figure 4 This is a schematic diagram showing the overall structure of the fuel cell system according to the second embodiment.

[0017] Figure 5 This is a schematic diagram showing the overall structure of the fuel cell system according to the third embodiment.

[0018] Figure 6 This is a schematic diagram showing the overall structure of the fuel cell system according to the fourth embodiment. Detailed Implementation

[0019] <First Implementation>

[0020] [A] Structure

[0021] Figure 1 This is a schematic diagram showing the overall structure of the fuel cell system according to the first embodiment.

[0022] like Figure 1 As shown, the fuel cell system of this embodiment includes a fuel cell unit 1. Additionally, the fuel cell system includes a cooling water circulation system S1, a heat exchange system S2, and a control unit 80.

[0023] The fuel cell system of this embodiment is used, for example, as a power source in a ship moving in the ocean, and is installed on the deck of the ship. The components constituting the fuel cell system will be described in turn.

[0024] [A-1] Fuel Cell Section 1

[0025] First, use Figure 2 and Figure 3 An example of fuel cell section 1 constituting a fuel cell system will be described.

[0026] Figure 2 This is a perspective view schematically showing the overall structure of the fuel cell section in the first embodiment. Figure 3 This is an enlarged cross-sectional view showing a portion of the fuel cell section in the first embodiment. Figure 2 In this diagram, the y-axis is along the vertical direction, the z-axis is along the first horizontal direction, and the x-axis is along a second horizontal direction orthogonal to the first horizontal direction. Figure 3 In, it is shown that... Figure 2 A portion of the cross section corresponding to the horizontal plane (xz plane) in the diagram.

[0027] like Figure 2 As shown, the fuel cell unit 1 includes a fuel cell stack 10. The fuel cell stack 10 includes a plurality of fuel cell cells 11 and a plurality of membranes 12, which are alternately stacked in the stacking direction. The fuel cell stack 10 is sandwiched between a pair of fastening plates 15 (end plates) in the stacking direction, and the pair of fastening plates 15 are fastened together by fastening components such as pull rods and belts (not shown).

[0028] [A-1-1] Fuel Cell Single Cell 11

[0029] In fuel cell stack 10, the fuel cell 11 is a polymer electrolyte type, such as... Figure 3 As shown, it includes a polymer electrolyte membrane 110, a fuel electrode 111, and an air electrode 112. The fuel cell 11 is a membrane / electrode assembly in which the polymer electrolyte membrane 110 is sandwiched between the fuel electrode 111 and the air electrode 112.

[0030] The polymeric electrolyte membrane 110 is, for example, made of a fluorine-based polymer material with sulfonic acid groups. The fuel electrode 111 and the air electrode 112 are, for example, constructed by supporting a platinum catalyst on a carbon black support.

[0031] [A-1-2] Diaphragm 12

[0032] In the fuel cell stack 10, the membrane 12 is composed of a porous body formed of a conductive material. A fuel electrode gas flow path F121 and an air electrode gas flow path F122 are formed in the membrane 12.

[0033] A fuel electrode gas flow path F121 is formed on the surface of the diaphragm 12 on the side of the fuel electrode 111. The fuel electrode gas flow path F121 is formed along the vertical direction (y-axis direction) to supply fuel electrode gas to the fuel electrode 111 of the fuel cell 11. There are multiple fuel electrode gas flow paths F121, which are spaced apart in the second horizontal direction (x-axis direction).

[0034] An air electrode gas flow path F122 is formed on the surface of the diaphragm 12 on the side of the air electrode 112. The air electrode gas flow path F122 is formed along a second horizontal direction (x-axis direction) orthogonal to a first horizontal direction (z-axis direction) along the stacking direction, and supplies air electrode gas to the air electrode 112 of the fuel cell single cell 11. Although not shown in the figure, there are multiple air electrode gas flow paths F122, which are spaced apart in the first horizontal direction (y-axis direction).

[0035] [A-2] Cooling water circulation system S1

[0036] like Figure 1 As shown, the cooling water circulation system S1 is configured such that cooling water CW circulates through the fuel cell unit 1.

[0037] Here, the cooling water circulation system S1 includes a cooling water pump P1. The cooling water pump P1 is provided for supplying cooling water CW to the fuel cell unit 1.

[0038] The cooling water CW, for example, is pure water, which is supplied from above in the vertical direction (y-axis direction) and discharged downwards in the fuel cell section 1. Specifically, the cooling water CW flows into the interior of the micropores of the membrane 12, which is composed of a porous material. The cooling water CW is supplied at a pressure lower than that of the fuel electrode gas and the air electrode gas. As a result, the generated water produced in the power generation reaction of the fuel cell section 1 and the condensate condensed inside the fuel cell section 1 can be removed to the outside of the fuel cell section 1, and the polymer electrolyte membrane 110 can be humidified and cooled due to the latent heat of vaporization.

[0039] [A-3] Heat exchange system S2

[0040] like Figure 1 As shown, the heat exchange system S2 is set up for heat exchange between seawater SW and cooling water CW circulating in the cooling water circulation system S1.

[0041] Here, the heat exchange system S2 includes a seawater heat exchanger 2 and a seawater pump P2. The seawater heat exchanger 2 is provided for heat exchange between seawater SW and cooling water CW circulating in the cooling water circulation system S1. The seawater pump P2 is provided for supplying seawater SW to the seawater heat exchanger 2. The heat exchange system S2 is a seawater circulation system, configured such that seawater SW drawn from the ocean (not shown) using the seawater pump P2 returns to the ocean after passing through the seawater heat exchanger 2.

[0042] [A-4] Control Unit 80

[0043] like Figure 1 As shown, the control unit 80 is provided for controlling the heat exchange between seawater SW and cooling water CW. Although not shown in the figure, the control unit 80 is configured to include an arithmetic unit (not shown) and a memory device (not shown). The arithmetic unit uses the program stored in the memory device to perform calculations. The control unit 80 takes temperature data detected by temperature sensors T11, T12a, T12b, and T21a as input signals, and outputs control signals obtained by processing these input signals to each unit, thereby controlling the operation of each unit.

[0044] Here, the control unit 80 controls the heat exchange between seawater SW and cooling water CW in a way that makes the temperature of the fuel cell unit 1 a predetermined temperature. For example, when the fuel cell unit 1 is operating normally, if the temperature of the cooling water CW used to cool the fuel cell unit 1 is above a predetermined value, the heat exchange between the seawater SW and cooling water CW is controlled in a way that the seawater SW cools the cooling water CW.

[0045] Furthermore, in this embodiment, the control unit 80 is configured to heat the cooling water CW using the heat of seawater SW when performing freeze prevention operation to prevent the cooling water CW from freezing. Specifically, when the temperature related to the cooling water circulation system S1 is below a first threshold TH1, and the temperature of the seawater SW used for heat exchange in the heat exchange system S2 is above a second threshold TH2, which is higher than the first threshold TH1 (TH1 < TH2), the control unit 80 increases the amount of heat exchange based on heat exchange, thereby heating the cooling water CW.

[0046] The first threshold TH1 is, for example, 3 to 4°C. The control unit 80 determines whether the temperature is below the first threshold TH1 based on the temperature data measured by the temperature sensor T11, which detects the temperature of the fuel cell unit 1. The second threshold TH2 is, for example, 5 to 10°C. The control unit 80 determines whether the temperature is above the second threshold TH2 based on the temperature data measured by the temperature sensor T21a, which detects the temperature of the seawater SW drawn by the seawater pump P2.

[0047] The control unit 80 increases the amount of heat exchange caused by heat exchange by driving at least one of the cooling water pump P1 and the seawater pump P2. That is, by increasing the discharge rate of at least one of the cooling water pump P1 and the seawater pump P2, the amount of heat exchange caused by heat exchange between the cooling water CW and the seawater SW is increased.

[0048] At this time, the control unit 80 controls the operation of at least one of the cooling water pump P1 and the seawater pump P2 in such a way that the temperature difference between the cooling water inflow temperature (related to the cooling water CW flowing into the seawater heat exchanger 2) and the cooling water outflow temperature (related to the cooling water CW flowing out of the seawater heat exchanger 2) is a preset set temperature difference. The cooling water inflow temperature is measured by temperature sensor T12a, and the cooling water outflow temperature is measured by temperature sensor T12b. The control unit 80 controls the operation such that the greater the difference between the cooling water inflow temperature and the cooling water outflow temperature and the preset set temperature difference, the greater the amount of heat exchange caused by the heat exchange between the cooling water CW and the seawater SW.

[0049] [B]Summary

[0050] As described above, in the fuel cell system of this embodiment, in the event that the cooling water CW may freeze, the heat from seawater SW, which has a higher temperature than the cooling water CW, is used to heat the cooling water CW. Therefore, this embodiment can easily and efficiently prevent the cooling water CW from freezing.

[0051] In the fuel cell system of this embodiment, the fuel cell 11 is a polymer electrolyte type (internal humidification type). Therefore, in order to improve power generation performance, it is necessary to reduce the proton resistance of the polymer electrolyte membrane 110 by increasing the water content of the polymer electrolyte membrane 110. Therefore, the cooling water CW is supplied not only for cooling but also for humidifying the polymer electrolyte membrane 110. Therefore, the cooling water CW is preferably pure water that will not adversely affect the fuel cell 11, and the use of antifreeze that will adversely affect the fuel cell 11 is not preferred. Therefore, when the fuel cell 11 is a polymer electrolyte type, it is preferable, as in this embodiment, to heat the cooling water CW using seawater SW, which has a higher temperature than the cooling water CW, thereby preventing the cooling water CW from freezing.

[0052] <Second Implementation>

[0053] [A] Structure

[0054] Figure 4 This is a schematic diagram showing the overall structure of the fuel cell system according to the second embodiment.

[0055] like Figure 4 As shown, in the fuel cell system of this embodiment, the structure of the heat exchange system S2 is the same as that of the first embodiment (refer to...). Figure 1 The differences are minor. Aside from this point and related points, this embodiment is identical to the first embodiment. Therefore, repetitive details are appropriately omitted.

[0056] In this embodiment, the heat exchange system S2 includes a heat exchange medium circulation system S21 and a seawater circulation system S22.

[0057] In the heat exchange system S2, the heat exchange medium circulation system S21 is configured to circulate the heat exchange medium PW used for heat exchange with the cooling water CW. The heat exchange medium circulation system S21 includes a primary heat exchanger 3 and a heat exchange medium pump P3. The primary heat exchanger 3 is provided for heat exchange between the heat exchange medium PW and the cooling water CW. The heat exchange medium pump P3 is provided for supplying the heat exchange medium PW to the primary heat exchanger 3. The heat exchange medium PW is, for example, water.

[0058] In the heat exchange system S2, the seawater circulation system S22 includes a seawater heat exchanger 2 and a seawater pump P2. The seawater heat exchanger 2 is provided for heat exchange between seawater SW and cooling water CW circulating in the cooling water circulation system S1. The seawater pump P2 is provided for supplying seawater SW to the seawater heat exchanger 2. The seawater circulation system S22 is configured such that seawater SW drawn from the ocean (not shown) using the seawater pump P2 returns to the ocean after passing through the seawater heat exchanger 2.

[0059] Similar to the first embodiment, the control unit 80 uses the heat of seawater SW to heat the cooling water CW in order to prevent the cooling water CW from freezing. That is, similar to the first embodiment, when the temperature related to the cooling water circulation system S1 is below a first threshold TH1 and the temperature of the seawater SW used for heat exchange in the heat exchange system S2 is above a second threshold TH2 (TH1 < TH2), the control unit 80 increases the amount of heat exchange caused by heat exchange, thereby heating the cooling water CW.

[0060] In this embodiment, the control unit 80 increases the amount of heat exchange caused by heat exchange by driving at least one of the cooling water pump P1, the seawater pump P2, and the heat exchange medium pump P3. Specifically, by increasing the discharge rate of at least one of the seawater pump P2 and the heat exchange medium pump P3, the amount of heat exchange caused by the heat exchange medium PW and the seawater SW is increased. Furthermore, by increasing the discharge rate of at least one of the cooling water pump P1 and the heat exchange medium pump P3, the amount of heat exchange caused by the heat exchange between the cooling water CW and the heat exchange medium PW is increased. Thus, in this embodiment, heat exchange between the cooling water CW and the seawater SW occurs via the heat exchange medium PW, thereby preventing the cooling water CW from freezing.

[0061] At this time, the control unit 80 controls the operation of at least one of the cooling water pump P1, seawater pump P2, and heat exchange medium pump P3 in a manner that makes the temperature difference between the heat exchange medium inflow temperature (related to the heat exchange medium PW flowing into the seawater heat exchanger 2) and the heat exchange medium outflow temperature (related to the heat exchange medium PW flowing out of the seawater heat exchanger 2) a preset set temperature difference. The heat exchange medium inflow temperature is measured by temperature sensor T12a, and the heat exchange medium outflow temperature is measured by temperature sensor T12b. The control unit 80 controls the operation such that the greater the difference between the heat exchange medium inflow temperature and the heat exchange medium outflow temperature and the preset set temperature difference, the greater the amount of heat exchange caused by the heat exchange between the heat exchange medium PW and the seawater SW.

[0062] [B]Summary

[0063] As described above, in the fuel cell system of this embodiment, heat exchange between cooling water CW and seawater SW is performed via heat exchange medium PW, thereby preventing the cooling water CW from freezing. Therefore, this embodiment can easily and efficiently prevent the cooling water CW from freezing. Furthermore, in this embodiment, when the heat exchange medium PW is pure water, even if the primary heat exchanger 3 breaks and the heat exchange medium PW mixes with the cooling water CW, the fuel cell section 1 will not break. In the case of the first embodiment, if the seawater heat exchanger 2 breaks, the seawater SW mixes with the cooling water CW, and the fuel cell section 1 may break. In this embodiment, the possibility of such a breakage is reduced.

[0064] <Third Implementation Method>

[0065] [A] Structure

[0066] Figure 5 This is a schematic diagram showing the overall structure of the fuel cell system according to the third embodiment.

[0067] like Figure 5 As shown, in the fuel cell system of this embodiment, the heat exchange system S2 is the same as in the second embodiment (refer to...). Figure 4 Similarly, it includes a heat exchange medium circulation system S21 and a seawater circulation system S22. However, in this embodiment, a portion of the structure of the heat exchange medium circulation system S21 and the seawater circulation system S22 differs from that of the second embodiment (see [reference]). Figure 4 The differences are minor. Aside from this point and related points, this embodiment is identical to the second embodiment. Therefore, repetitive details are appropriately omitted.

[0068] In this embodiment, the heat exchange medium circulation system S21 is as follows: Figure 5 As shown, it also includes a heat source 50 (first heat source), a seawater heat exchanger bypass flow path BP1 (first seawater heat exchanger bypass flow path), a seawater heat exchanger bypass valve BV1 (first seawater heat exchanger bypass valve), and a seawater heat exchanger inlet valve V1.

[0069] The heat exchange medium PW discharged from the primary heat exchanger 3 flows through the heat source 50. The heat source 50 is, for example, a battery that stores electricity generated by the fuel cell unit 1. Alternatively, the heat source 50 may be an inverter, a refrigeration cycle condenser, a heat exchanger containing a cooling medium (cooling device), or other similar equipment.

[0070] The bypass flow path BP1 of the seawater heat exchanger is configured such that the heat exchange medium PW flowing out from the heat source 50 bypasses the seawater heat exchanger 2 and flows to the primary heat exchanger 3.

[0071] The bypass valve BV1 of the seawater heat exchanger is installed in the bypass flow path BP1 of the seawater heat exchanger.

[0072] The seawater heat exchanger inlet valve V1 is located in the flow path of the heat exchange medium PW flowing from the heat source 50 to the seawater heat exchanger 2, at a position that is downstream of the inlet of the seawater heat exchanger bypass flow path BP1 and upstream of the seawater heat exchanger 2.

[0073] In this embodiment, the temperature sensor T12a, used to measure the inflow temperature of the heat exchange medium, is positioned upstream of the inlet of the bypass flow path BP1 of the seawater heat exchanger during the flow of the heat exchange medium PW.

[0074] In addition, in this embodiment, a temperature sensor T21b for measuring the seawater inflow temperature related to the seawater SW flowing into the seawater heat exchanger 2 is provided between the seawater heat exchanger 2 and the seawater pump P2.

[0075] Furthermore, in this embodiment, the control unit 80 adjusts the heat exchange between the cooling water CW and the seawater SW via the heat exchange medium PW by further controlling the operation of the seawater heat exchanger bypass valve BV1 and the seawater heat exchanger inlet valve V1.

[0076] Specifically, when starting up the fuel cell unit 1, the control unit 80 opens the seawater heat exchanger bypass valve BV1 and completely closes the seawater heat exchanger inlet valve V1 when starting the heat exchange medium pump P3. Then, when the temperature measured by the temperature sensor T11, which detects the temperature of the fuel cell unit 1, rises to the operating temperature of the fuel cell unit 1 (e.g., 60°C to 80°C), the control unit 80 completely closes the seawater heat exchanger bypass valve BV1 and opens the seawater heat exchanger inlet valve V1. This allows the start-up and operation of the fuel cell unit 1 to be completed earlier.

[0077] During freeze prevention operation, if the temperature measured by temperature sensor T12a is higher than the temperature measured by temperature sensor T21b (t21a≥t21b), the control unit 80 opens the seawater heat exchanger bypass valve BV1 and completely closes the seawater heat exchanger inlet valve V1. As a result, the heat exchange medium PW flows through the heat exchange medium pump P3, bypassing the seawater heat exchanger 2, to the primary heat exchanger 3 via the seawater heat exchanger bypass path BP1.

[0078] On the other hand, during freeze prevention operation, if the temperature measured by temperature sensor T12a is less than the temperature measured by temperature sensor T21b (t21a < t21b), the control unit 80 completely closes the seawater heat exchanger bypass valve BV1 and opens the seawater heat exchanger inlet valve V1. As a result, the heat exchange medium PW flows through the heat exchange medium pump P3, bypassing the seawater heat exchanger bypass path BP1, and through the seawater heat exchanger 2 to the primary heat exchanger 3.

[0079] [B]Summary

[0080] As described above, in the fuel cell system of this embodiment, similarly to the second embodiment, heat exchange between the cooling water CW and the seawater SW is performed via the heat exchange medium PW, thereby preventing the cooling water CW from freezing. Therefore, this embodiment can easily and efficiently prevent the cooling water CW from freezing.

[0081] In addition, in this embodiment, when the fuel cell unit 1 is started up, the operation of the seawater heat exchanger bypass valve BV1 and the operation of the seawater heat exchanger inlet valve V1 are controlled as described above, so the start-up operation can be completed earlier.

[0082] Furthermore, in this embodiment, when performing freeze prevention operation, the heat source 50 is used appropriately as described above, thus effectively performing freeze prevention.

[0083] <Fourth Implementation>

[0084] [A] Structure

[0085] Figure 6 This is a schematic diagram showing the overall structure of the fuel cell system according to the fourth embodiment.

[0086] like Figure 6 As shown, in the fuel cell system of this embodiment, the heat exchange system S2 is the same as that in the third embodiment (see...). Figure 5 Similarly, it includes a heat exchange medium circulation system S21 and a seawater circulation system S22. However, in this embodiment, a portion of the structure of the seawater circulation system S22 is similar to that of the third embodiment (see [reference]). Figure 4 The differences are minor. Aside from this point and related points, this embodiment is identical to the third embodiment. Therefore, repetitive details are appropriately omitted.

[0087] In this embodiment, the seawater circulation system S22 is as follows: Figure 6As shown, it also includes a heat source 60 (second heat source), a seawater heat exchanger bypass flow path BP2 (second seawater heat exchanger bypass flow path), and a seawater heat exchanger bypass valve BV2 (second seawater heat exchanger bypass valve).

[0088] Heat source 60 supplies the flow of seawater SW discharged from seawater pump P2. Heat source 60 is a refrigeration cycle condenser, a heat exchanger for the cooling medium (cooling device), and other equipment.

[0089] The seawater heat exchanger bypass flow path BP2 is configured such that the seawater SW flowing out of the heat source 60 flows around the seawater heat exchanger 2.

[0090] The bypass valve BV2 of the seawater heat exchanger is installed in the bypass flow path BP2 of the seawater heat exchanger.

[0091] In addition, in this embodiment, a temperature sensor T21b for measuring the seawater inflow temperature related to the seawater SW flowing into the seawater heat exchanger 2 is provided between the inlet of the seawater heat exchanger bypass path BP2 and the seawater heat exchanger 2.

[0092] Furthermore, in this embodiment, the control unit 80 further controls the operation of the seawater heat exchanger bypass valve BV2, thereby adjusting the heat exchange between the cooling water CW and the seawater SW via the heat exchange medium PW.

[0093] Specifically, during normal operation of the fuel cell unit 1, when the temperature t21b measured by the temperature sensor T21b is higher than a predetermined set temperature (e.g., 20°C to 40°C), the control unit 80 increases the discharge rate of the seawater pump P2 and opens the seawater heat exchanger bypass valve BV2. Therefore, even if the temperature of the seawater SW flowing from the heat source 60 is higher than the set temperature due to heat exchange in the heat source 60, the heat exchange rate in the seawater heat exchanger 2 can be appropriately maintained. This prevents an increase in pump load due to excessive flow in the seawater heat exchanger 2 and ensures an appropriate heat exchange rate.

[0094] When performing freeze prevention operation, the control unit 80 generally keeps all bypass valves BV2 of the seawater heat exchanger closed. Furthermore, if the measured temperature t12a of temperature sensor T12a is below the measured temperature t21b of temperature sensor T21b (t12a≤t21b), the control unit 80 continues to drive the seawater pump P2 until the measured temperature t11 of temperature sensor T11 reaches or exceeds the set temperature (e.g., 10°C) for the cooling water CW to not freeze.

[0095] When the temperature measured by temperature sensor T12a is higher than the temperature measured by temperature sensor T21b (t12a > t21b), the control unit 80 drives the seawater pump P2, but opens the seawater heat exchanger bypass valve BV1 and closes the seawater heat exchanger inlet valve V1. That is, heat exchange between the heat exchange medium PW and the seawater SW does not occur in the seawater heat exchanger 2.

[0096] If the measured temperature t21b (the temperature of the heat exchange medium PW flowing out from the heat source 60) measured by the temperature sensor T21b is higher than the preset set temperature, the control unit 80 increases the flow rate of the seawater pump P2 in such a way as to achieve the set temperature, and controls the operation of the seawater heat exchanger bypass valve BV2.

[0097] [B]Summary

[0098] As described above, in the fuel cell system of this embodiment, similarly to the third embodiment, heat exchange between the cooling water CW and the seawater SW is performed via the heat exchange medium PW, thereby preventing the cooling water CW from freezing. Therefore, this embodiment can easily and efficiently prevent the cooling water CW from freezing.

[0099] Furthermore, in this embodiment, during normal operation of the fuel cell unit 1, the operation of the seawater pump P2 and the operation of the seawater heat exchanger bypass valve BV2 are controlled as described above. Therefore, as described above, the heat exchange rate in the seawater heat exchanger 2 can be appropriately maintained.

[0100] Furthermore, in this embodiment, when performing freeze prevention operation, the heat from the heat source 60 is appropriately used as described above, thus effectively performing freeze prevention.

[0101] [C] Variation Example

[0102] In this embodiment, the situation is the same as in the third embodiment (see...). Figure 5 Similarly, the heat exchange medium circulation system S21 is shown with a heat source 50, a seawater heat exchanger bypass flow path BP1, a seawater heat exchanger bypass valve BV1, and a seawater heat exchanger inlet valve V1, but it is not limited to this. The heat source 50, the seawater heat exchanger bypass flow path BP1, the seawater heat exchanger bypass valve BV1, and the seawater heat exchanger inlet valve V1 may not be included in the heat exchange medium circulation system S21.

[0103] <Other>

[0104] Several embodiments of the present invention have been described, but these embodiments are provided by way of example and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope or spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

[0105] [Explanation of reference numerals in the attached figures]

[0106] 1: Fuel cell section, 2: Seawater heat exchanger, 3: Primary heat exchanger, 10: Fuel cell stack, 11: Fuel cell, 12: Separator, 15: Fastening plate, 50: Heat source (first heat source), 60: Heat source (second heat source), 80: Control unit, 110: Polymer electrolyte membrane, 111: Fuel electrode, 112: Air electrode, BP1: Seawater heat exchanger bypass path (first seawater heat exchanger bypass path), BP2: Seawater heat exchanger bypass path (second seawater heat exchanger bypass path), BV1: Seawater heat exchanger bypass valve (first seawater heat exchanger bypass valve), BV2: Seawater heat exchanger bypass valve (second seawater heat exchanger bypass valve), CW: cooling water, F121: fuel electrode gas flow path, F122: air electrode gas flow path, P1: cooling water pump, P2: seawater pump, P3: heat exchange medium pump, PW: heat exchange medium, S1: cooling water circulation system, S2: heat exchange system, S21: heat exchange medium circulation system, S22: seawater circulation system, SW: seawater, T11: temperature sensor, T12a: temperature sensor, T12b: temperature sensor, T21a: temperature sensor, T21b: temperature sensor, V1: seawater heat exchanger inlet valve.

Claims

1. A fuel cell system including a fuel cell section, the fuel cell system comprising: a cooling water circulation system for circulating cooling water via the fuel cell section; a heat exchange system for performing heat exchange between seawater and the cooling water circulating in the cooling water circulation system; and a control section for controlling the heat exchange, wherein in a case where a temperature related to the cooling water circulation system is below a first threshold value and a temperature of the seawater used for performing the heat exchange in the heat exchange system is above a second threshold value higher than the first threshold value, the control section heats the cooling water by the heat exchange.

2. The fuel cell system according to claim 1, wherein the cooling water circulation system has a cooling water pump for supplying the cooling water to the fuel cell section, wherein the heat exchange system has: a seawater heat exchanger for performing heat exchange between the seawater and the cooling water circulating in the cooling water circulation system; and a seawater pump for supplying the seawater to the seawater heat exchanger, and wherein the control section increases an amount of heat exchange caused by the heat exchange by driving at least one of the cooling water pump and the seawater pump.

3. The fuel cell system according to claim 2, wherein the control section controls an action of at least one of the cooling water pump and the seawater pump in such a manner that a temperature difference between a cooling water inflow temperature at which the cooling water flows into the seawater heat exchanger and a cooling water outflow temperature at which the cooling water flows out from the seawater heat exchanger becomes a set temperature difference that is set in advance.

4. The fuel cell system according to claim 1, wherein the cooling water circulation system has a cooling water pump for supplying the cooling water to the fuel cell section, wherein the heat exchange system has: a heat exchange medium circulation system for circulating a heat exchange medium for performing heat exchange therebetween; a seawater heat exchanger for performing heat exchange between the heat exchange medium and the seawater; and a seawater pump for supplying the seawater to the seawater heat exchanger, and wherein the heat exchange medium circulation system has: a primary heat exchanger for performing heat exchange between the heat exchange medium and the cooling water; and a heat exchange medium pump for supplying the heat exchange medium to the primary heat exchanger, and wherein the control section increases an amount of heat exchange caused by the heat exchange by driving at least one of the cooling water pump, the seawater pump, and the heat exchange medium pump.

5. The fuel cell system according to claim 4, wherein the control section controls an action of at least one of the cooling water pump, the seawater pump, and the heat exchange medium pump in such a manner that a temperature difference between a heat exchange medium inflow temperature at which the heat exchange medium flows into the seawater heat exchanger and a heat exchange medium outflow temperature at which the heat exchange medium flows out from the seawater heat exchanger becomes a set temperature difference that is set in advance.

6. The fuel cell system according to claim 4 or 5, wherein the heat exchange medium circulation system comprises: a first heat source for flowing the heat exchange medium discharged from the primary heat exchanger; and a second heat source for flowing the heat exchange medium discharged from the seawater heat exchanger. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ a first seawater heat exchanger bypass passage for the heat exchange medium flowing from the first heat source to flow to the primary heat exchanger while bypassing the seawater heat exchanger; a first seawater heat exchanger bypass valve provided in the first seawater heat exchanger bypass passage; and a seawater heat exchanger inlet valve provided in the flow path of the heat exchange medium flowing from the first heat source to the seawater heat exchanger at a position downstream of an inlet of the first seawater heat exchanger bypass passage and upstream of the seawater heat exchanger, the control section adjusts the heat exchange by further controlling the operation of the first seawater heat exchanger bypass valve and the operation of the seawater heat exchanger inlet valve.

7. The fuel cell system according to any one of claims 4 to 6, the heat exchange system is provided with: a second heat source for the seawater discharged from the seawater pump to flow; a second seawater heat exchanger bypass passage for the seawater flowing from the second heat source to flow while bypassing the seawater heat exchanger; and a second seawater heat exchanger bypass valve provided in the second seawater heat exchanger bypass passage, the control section adjusts the heat exchange by further controlling the operation of the second seawater heat exchanger bypass valve.

Images