Fuel Cell Systems

Abstract

To provide a fuel cell system which can control the temperature of liquid fuel such that its temperature range may be suitable for an electrode reaction in an electrode structure.SOLUTION: A fuel cell system comprises a heater 50 which heats liquid fuel in a fuel supply passage 11 of an anode-side separator 10. Along the fuel supply passage 11, the heater 50 is divided into a first heater 51 (a first high-temperature heater 51a and a first low-temperature heater 51b), a second heater 52 (a second high-temperature heater 52a and a second low-temperature heater 52b), and a third heater 53. In the first heater 51, the second heater 52, and the third heater 53, the amount of heat input is controlled such that the liquid fuel temperature on a fuel supply port 12 side of the liquid fuel into the fuel supply passage 11 may be suitable for an electrode reaction before the heaters heat the liquid fuel flowing through the fuel supply passage 11.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a fuel cell system. [Background technology]

[0002] Fuel cells, particularly solid polymer electrolyte fuel cells, generally include an electrode structure consisting of an anode electrode formed on one side of an electrolyte membrane and a cathode electrode formed on the other side. In solid polymer electrolyte fuel cells, fuel is supplied to the anode electrode and an oxidant is supplied to the cathode electrode from the outside, causing an electrode reaction in the electrode structure to generate electricity.

[0003] In recent years, direct fuel cells have been developed that directly use liquid fuels such as methanol and formic acid as the fuel supplied to the anode electrode. Liquid fuels are easier to handle and have a higher energy density per volume than hydrogen gas fuels, making them extremely useful.

[0004] In a fuel cell that directly uses liquid fuel, it is necessary to maintain the anode electrode side of the electrode structure in a temperature range suitable for the electrode reaction throughout the power generation operation. For this reason, for example, Patent Document 1 discloses a configuration of a fuel cell system that can appropriately control the temperatures of the fuel cell and the fuel storage unit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-49345 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a direct type fuel cell, in order to promote the electrode reaction in the electrode structure and generate power efficiently, it is preferable to supply liquid fuel to the anode electrode in a temperature range suitable for the electrode reaction. In this case, for example, it is possible to preheat the liquid fuel to a temperature range suitable for the electrode reaction in a supply tank that stores the liquid fuel and supply it. However, when the liquid fuel is heated in the supply tank and supplied to the anode electrode, temperature changes occur during the supply, and a lot of energy is required to heat a large amount of liquid fuel and maintain the temperature.

[0007] In addition, when electricity is generated by an electrode reaction in the electrode structure, Joule heat is generated by the current generated by the power generation, which results in an increase in the temperature of the electrode structure. Therefore, in a fuel cell, in order to maintain a temperature range suitable for the electrode reaction, it is necessary to adjust the temperature of the liquid fuel supplied to the anode electrode in accordance with the generated Joule heat.

[0008] An object of the present invention is to provide a fuel cell system capable of controlling the temperature of liquid fuel so that it falls within a temperature range suitable for the electrode reaction in the electrode structure. [Means for solving the problem]

[0009] One aspect of the present invention is an electrode structure having an electrolyte membrane, an anode electrode, and a cathode electrode; The above an anode-side separator having a fuel supply flow path for supplying a liquid fuel to the anode electrode; The above a cathode-side separator having an oxidant supply flow path for supplying an oxidant to the cathode electrode; The above Anode side separator and The above Between the cathode separator The above forming a single cell in which the electrode structure is disposed; The above a fuel cell that generates electricity through an electrode reaction in the electrode structure; The above Anode side separator The above In the fuel supply passage The aboveA heater for heating the liquid fuel; The above A control device that controls the operation of the heater, The heater is divided and disposed in the fuel supply passage, The above The control device includes: The above For fuel supply passage The above On the liquid fuel supply side The above The temperature of the liquid fuel The above To achieve a temperature range suitable for electrode reactions The above Controlling the heating by the heater, The above The heater The above Flowing through the fuel supply passage The above Heating liquid fuel death, When the liquid fuel on the supply side is heated to a temperature range suitable for the electrode reaction and flows through the fuel supply flow path, The fuel cell system controls operation of the heater so that the amount of heat input per unit area from the heater to the liquid fuel gradually decreases along the liquid fuel discharge side from the supply side of the fuel supply flow path. Another aspect of the present invention is a fuel cell comprising an electrode structure having an electrolyte membrane, an anode electrode, and a cathode electrode, an anode-side separator having a fuel supply flow path for supplying a liquid fuel to the anode; a cathode-side separator having an oxidant supply flow path for supplying an oxidant to the cathode electrode, the electrode structure being disposed between a pair of the anode-side separator and the cathode-side separator to form a single cell, and generating power through an electrode reaction in the electrode structure; a heater that heats the liquid fuel in the fuel supply flow channel of the anode-side separator; A control device that controls the operation of the heater, The heater is divided and disposed in the fuel supply passage, The control device includes: heating the liquid fuel flowing through the fuel supply flow passage by controlling heating by the heater so that a temperature of the liquid fuel on a supply side of the liquid fuel to the fuel supply flow passage is within a temperature range suitable for the electrode reaction; and The fuel cell system controls the operation of each of the divided heaters based on the position of each of the divided heaters relative to the fuel supply flow path and Joule heat corresponding to the amount of current generated in conjunction with power generation by the electrode reaction in the electrode structure.

[0010] According to this, the fuel cell system can include a heater that is controlled by the control device and heats the liquid fuel in the fuel supply flow path of the anode-side separator. Therefore, by the control device controlling the heater, the liquid fuel flowing through the fuel supply flow path can be heated and the temperature of the liquid fuel can be maintained in a temperature range suitable for the electrode reaction. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a configuration of a fuel cell system. [Diagram 2] FIG. 1 is a diagram showing the configuration of a fuel cell stack formed by stacking unit cells. [Diagram 3] FIG. 2 is a diagram showing the structure of an anode-side separator. [Figure 4] FIG. 4 is a diagram showing the configuration of the opposing surface of a cathode-side separator. [Diagram 5] 5A and 5B are diagrams illustrating a configuration of a seal member. [Figure 6] FIG. 2 is a diagram showing the configuration of an MEA. [Figure 7] FIG. 7 is a cross-sectional view showing a cross section of the MEA taken along line VII-VII in FIG. [Figure 8] FIG. 4 is a diagram showing the configuration of a heater. [Figure 9] FIG. 4 is a cross-sectional view for explaining the operation of a heater. [Figure 10] 13 is a diagram for explaining a relationship between a generated current amount and a position in a fuel supply flow passage according to a first modified example. FIG. [Figure 11] FIG. 11 is a diagram showing the configuration of a heater according to a second modified example. [Figure 12] 13 is a diagram for explaining a fuel supply flow path according to a third modified example. FIG. [Figure 13] FIG. 13 is a diagram showing the configuration of a heater according to a third modified example. [Figure 14] FIG. 13 is a diagram showing another configuration of the heater according to the third modified example. [Figure 15] FIG. 13 is a diagram showing another configuration of the heater according to the third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (1. Overview of Fuel Cell System) In this embodiment, a solid polymer fuel cell is used as an example of the fuel cell. That is, in the fuel cell of this embodiment, an anode electrode is formed on one side of an electrolyte membrane, and a cathode electrode is formed on the other side of the electrolyte membrane. Here, the electrolyte membrane, the anode electrode, and the cathode electrode form an MEA (Membrane-Electrode-Assembly), which is an electrode structure.

[0013] The fuel cell of this example is provided with an anode-side separator (including a collector (current collecting function)) that supplies fuel to the anode electrode, and a cathode-side separator (including a collector (current collecting function)) that supplies an oxidant (oxidant gas) to the cathode electrode. The fuel cell of this example is formed into one cell (hereinafter referred to as a single cell) that includes an MEA, an anode-side separator, and a cathode-side separator, and a fuel cell stack is formed by stacking a plurality of single cells.

[0014] In this example, the fuel supplied to the anode electrode of the fuel cell can be exemplified by liquid fuels such as formic acid (HCOOH), methanol (CH3OH), and ethanol (C2H5OH). Here, in the fuel cell described below, a case where formic acid is directly used as the liquid fuel supplied is exemplified. That is, the fuel cell in this example is a polymer electrolyte fuel cell, and a direct formic acid fuel cell (DFAFC) is exemplified. In addition, in this example, the oxidant (oxidant gas) supplied to the cathode electrode of the fuel cell can be exemplified by oxygen (O2) gas, air, and the like. Here, in the fuel cell described below, a case where air is used as the oxidant gas, i.e., the oxidant gas, supplied is exemplified.

[0015] In the case of a direct formic acid fuel cell, when formic acid, a liquid fuel, is directly supplied to the anode electrode of the MEA and air (O2), an oxidant (oxidant gas), is supplied to the cathode electrode of the MEA, an electrode reaction occurs in the MEA to generate electricity. In this case, the electrode reaction in the MEA is promoted by maintaining the temperature of the formic acid, a liquid fuel, supplied to the anode electrode of the MEA in a temperature range suitable for the electrode reaction, resulting in efficient power generation.

[0016] Therefore, in order to heat and maintain the temperature of the formic acid, which is the liquid fuel supplied to the anode electrode, in a temperature range suitable for the electrode reaction, the fuel cell system of this example is provided with a heater that is arranged along the fuel supply flow path formed in the anode-side separator and heats the liquid fuel flowing through the fuel supply flow path.

[0017] The heater in this example is controlled to operate so that the temperature of formic acid on the formic acid supply side of the fuel supply flow path is in a temperature range suitable for the electrode reaction, and heats the formic acid flowing through the fuel supply flow path. The heater in this example is divided and arranged in the fuel supply flow path, and is controlled so that the heat input per unit area to formic acid gradually decreases from the formic acid supply side to the formic acid discharge side of the fuel supply flow path. Therefore, the temperature of formic acid supplied to the anode electrode of the MEA is heated and maintained in a temperature range suitable for the electrode reaction, promoting the electrode reaction in the MEA and enabling efficient power generation.

[0018] (2. Details of the configuration of direct formic acid fuel cell FC) The configuration of a direct formic acid fuel cell FC (hereinafter simply referred to as "fuel cell FC") of this example will be described below with reference to the drawings. As shown in FIG. 1, the fuel cell FC of this example forms a fuel cell stack S. The fuel cell stack S is in a state in which a plurality of unit cells U are stacked, and the stacked unit cells U are held by a holder H and a bolt B. The fuel cell stack S of this example is horizontally disposed, with a plurality of unit cells U arranged vertically stacked along the horizontal direction.

[0019] A fuel pump P1 that pressurizes and supplies formic acid, which is a liquid fuel stored in a supply tank T, is connected to a connection part K1 of the fuel cell stack S via piping (not shown). In addition, a blower P2 (pressurizing pump) that pressurizes and supplies air as an oxidizer (oxidizer gas) is connected to a connection part K2 of the fuel cell stack S via piping (not shown).

[0020] 2, the unit cell U includes an anode side separator 10 and a cathode side separator 20. The unit cell U of this example includes a seal member 30 and an MEA 40 that are disposed between the anode side separator 10 and the cathode side separator 20 and laminated therebetween.

[0021] Moreover, in the unit cell U of this example, a heater 50 for heating formic acid, which is a liquid fuel, is attached to the anode side separator 10. In this example, the heater 50 is disposed between the anode side separator 10 and the holder H (see FIG. 1 ). However, as long as it is possible to heat formic acid to a temperature range suitable for the electrode reaction, the location of the heater 50 is not limited, and for example, the heater 50 can be disposed on the surface of the holder H opposite to the surface facing the anode side separator 10.

[0022] The anode side separator 10 is formed in a plate shape as shown in Fig. 3. The anode side separator 10 in this example has a current collecting function (so-called collector) for collecting electricity generated by the electrode reaction in the MEA 40, and is made of a metal material, for example, a thin plate of stainless steel such as SUS316, which is subjected to a conductive treatment such as gold plating. Note that, although the anode side separator 10 is made of a metal material in this example, it is also possible to form it from a conductive nonmetallic material (for example, carbon or a composite material with carbon).

[0023] A fuel supply flow channel 11 for supplying formic acid, which is a liquid fuel, to the anode electrode layer AE is formed in the central portion of the anode-side separator 10, i.e., in a position facing the MEA 40 (more specifically, the anode electrode layer AE, which is the anode electrode described later). In this example, the fuel supply flow channel 11 has a bent portion 11a and a straight portion 11b, and is formed in a serpentine shape, as shown in Fig. 3. Here, the bent portion 11a changes the flow direction of formic acid, which is the liquid fuel, flowing through the fuel supply flow channel 11 by 90 degrees or more (180 degrees in this example).

[0024] Further, on the peripheral portion of the anode side separator 10, a fuel supply port 12 for supplying formic acid to the fuel supply channel 11 and a fuel discharge port 13 for discharging formic acid that has passed through the fuel supply channel 11 are provided.

[0025] The fuel supply port 12 corresponds to the supply side of formic acid, which is a liquid fuel, to the fuel supply flow path 11, and pressurized formic acid is supplied by a fuel pump P1 (see FIG. 1) provided outside the fuel cell stack S. The fuel pump P1 pressurizes and supplies formic acid stored in a supply tank T (see FIG. 1). The fuel discharge port 13 corresponds to the discharge side of formic acid, which is a liquid fuel, in the fuel supply flow path 11, and is connected to a recovery tank (not shown) provided outside the fuel cell stack S, and discharges discharged formic acid to the recovery tank. Note that the anode-side separator of this example illustrates a case in which the fuel supply port 12 is provided on the upper side in the vertical direction and the fuel discharge port 13 is provided on the lower side in the vertical direction when the fuel cell stack S is installed. However, if necessary, the fuel supply port 12 may be provided on the lower side in the vertical direction and the fuel discharge port 13 may be provided on the upper side in the vertical direction.

[0026] As a result, in the unit cell U of this example, formic acid pressurized by the fuel pump P1 from the supply tank T is supplied from the fuel supply port 12 to the fuel supply flow path 11, and the formic acid flowing through the fuel supply flow path 11 reaches the fuel outlet 13 while contacting the anode electrode layer AE. That is, in this example, the formic acid supplied from the fuel supply port 12 flows vertically from the upper side to the lower side in the fuel supply flow path 11 and reaches the fuel outlet 13. Then, the formic acid that has reached the fuel outlet 13, i.e., the unreacted formic acid, is recovered in the recovery tank.

[0027] The peripheral portion of the anode-side separator 10 is provided with through-holes 14 and 15 for supplying air to the cathode-side separator 20 constituting the unit cell U and discharging unreacted air. The through-holes 14 and 15 are provided, for example, at positions shifted by 90 degrees from the fuel supply port 12 and the fuel discharge port 13. The peripheral portion of the anode-side separator 10 is further provided with a plurality of large-diameter insertion holes 16 (eight in FIG. 3) for inserting the bolts B of the holder H, and an electrode portion 17 for extracting electricity to the outside. The electrode portion 17 may be provided, for example, only in the anode-side separator 10 constituting the unit cell U located at the end when the fuel cell stack S is formed.

[0028] The cathode-side separator 20 is formed in a plate shape as shown in Fig. 4. The cathode-side separator 20 in this example also has a current collecting function (so-called collector) for collecting electricity generated by the electrode reaction in the MEA 40, and is made of a metal material, for example, a thin plate of stainless steel such as SUS316, which is subjected to a conductive treatment such as gold plating. In this example, the cathode-side separator 20 is also made of a metal material like the anode-side separator 10, but it is also possible to form it from a conductive nonmetallic material (for example, carbon or a composite material with carbon).

[0029] An oxidant supply channel 21 for supplying air, which is an oxidant (oxidant gas), to the cathode electrode layer CE is formed in the central portion of the cathode-side separator 20. The oxidant supply channel 21 in this example is formed in a serpentine shape, as shown in FIG.

[0030] Further, an oxidant supply port 22 for supplying air, i.e., oxygen (O2), to the oxidant supply flow path 21, and an oxidant discharge port 23 for discharging the air that has passed through the oxidant supply flow path 21 are provided at the peripheral portion of the cathode side separator 20. The oxidant supply port 22 is supplied with air pressurized by a blower P2 (see FIG. 1) provided outside the fuel cell stack S. In this example, the fuel cell FC is provided with the blower P2, and the air is pressurized and supplied by the blower P2. However, the blower P2 may be omitted if necessary.

[0031] The oxidant discharge port 23 discharges the discharged air to the outside of the fuel cell stack S. As a result, in the single cell U of this example, air pressurized by the blower P2, i.e., oxygen (O2), is supplied from the oxidant supply port 22 to the oxidant supply flow path 21, and the air, i.e., oxygen (O2), flowing through the oxidant supply flow path 21 reaches the oxidant discharge port 23 while contacting the cathode electrode layer CE. Then, the air (oxygen (O2)) that has reached the oxidant discharge port 23, i.e., the unreacted air, is discharged to the outside of the fuel cell stack S.

[0032] Further, a through hole 24 and a through hole 25 are provided in the peripheral portion of the cathode side separator 20 for supplying formic acid to the anode side separator 10 constituting the single cell U and discharging unreacted formic acid. The through holes 24, 25 are provided at positions shifted by, for example, 90 degrees from the oxidant supply port 22 and the oxidant discharge port 23.

[0033] Furthermore, a plurality of large-diameter insertion holes 26 (eight in Figs. 4 and 5) for inserting the bolts B of the holder H are provided in the peripheral portion of the cathode-side separator 20, and an electrode portion 27 for extracting electricity to the outside is also provided. Note that when the fuel cell stack S is formed, the electrode portion 27 can be provided, for example, only in the cathode-side separator 20 constituting the unit cell U located at the end.

[0034] Here, the fuel supply port 12 of the anode side separator 10 can be communicated with the through hole 24 of the cathode side separator 20, and the fuel discharge port 13 of the anode side separator 10 can be communicated with the through hole 25 of the cathode side separator 20. Also, the oxidant supply port 22 of the cathode side separator 20 can be communicated with the through hole 14 of the anode side separator 10, and the oxidant discharge port 23 of the cathode side separator 20 can be communicated with the through hole 15 of the anode side separator 10. That is, the through holes 14, 15 of the anode side separator 10 are formed corresponding to the oxidant supply port 22 and the oxidant discharge port 23 of the cathode side separator 20, and the through holes 24, 25 of the cathode side separator 20 are formed corresponding to the fuel supply port 12 and the fuel discharge port 13 of the anode side separator 10.

[0035] The seal member 30 is formed in a plate shape as shown in Fig. 5. Here, the seal member 30 is formed from an elastic material, for example, a rubber material such as EPDM, an elastomer material, etc. Two seal members 30 are used as a pair, and each seal member 30 holds an MEA 40 and is also held between the anode side separator 10 and the cathode side separator 20.

[0036] The sealing member 30 has a receiving portion 31 that penetrates in the center so as to receive the anode electrode layer AE and cathode electrode layer CE of the MEA 40. With this, when the sealing member 30 holds the MEA 40, formic acid supplied via the fuel supply flow passage 11 of the anode-side separator 10 flows inside the receiving portion 31, and is supplied to the anode electrode layer AE. Furthermore, with the sealing member 30 holding the MEA 40, air supplied via the oxidant supply flow passage 21 of the cathode-side separator 20 flows inside the receiving portion 31, and is supplied to the cathode electrode layer CE.

[0037] Furthermore, in the peripheral portion of the seal member 30, through holes 32, 33 are formed at positions corresponding to the fuel supply port 12 (corresponding to the through hole 24 of the cathode side separator 20) and the fuel discharge port 13 (corresponding to the through hole 25 of the cathode side separator 20) provided in the anode side separator 10 when the unit cell U is formed. As a result, when the unit cell U is formed, the fuel supply port 12 (through hole 24) communicates with the through hole 32, and the fuel discharge port 13 (through hole 25) communicates with the through hole 33.

[0038] Furthermore, in the peripheral portion of the seal member 30, through holes 34, 35 are formed at positions corresponding to the oxidant supply port 22 (corresponding to the through hole 14 of the anode side separator 10) and the oxidant discharge port 23 (corresponding to the through hole 15 of the anode side separator 10) provided in the cathode side separator 20 when the unit cell U is formed. As a result, in the state where the unit cell U is formed, the oxidant supply port 22 (through hole 14) communicates with the through hole 34, and the oxidant discharge port 23 (through hole 15) communicates with the through hole 35. Furthermore, in the peripheral portion of the seal member 30, an insertion hole 36 is formed so that the bolt B of the holder H can be inserted therethrough.

[0039] 6 and 7, the MEA 40 as an electrode structure has as its main components an electrolyte membrane EF, an anode electrode layer AE as an anode electrode to which formic acid is supplied, and a cathode electrode layer CE as a cathode electrode to which air is supplied, which are formed by stacking layers of a predetermined catalyst on the electrolyte membrane EF. Note that the electrode reactions of the electrolyte membrane EF, anode electrode layer AE, and cathode electrode layer CE are widely known, and therefore detailed description thereof will be omitted in the following description.

[0040] The electrolyte membrane EF of this embodiment is a cation (more specifically, a hydrogen ion (H + )) selectively permeable to the electrolyte membrane EF (e.g., "Nafion (registered trademark)" manufactured by DuPont, "Flemion (registered trademark)" and "Aciplex (registered trademark)" manufactured by Asahi Glass Co., Ltd., and "Gore Select (registered trademark)" manufactured by Gore). In addition, as shown in FIG. 6, in the peripheral portion of the electrolyte membrane EF, in a state in which the unit cell U is formed, through holes 41 and 42 are formed at positions corresponding to the fuel supply port 12 (corresponding to the through hole 24 of the cathode side separator 20), the fuel discharge port 13 (corresponding to the through hole 25 of the cathode side separator 20) provided in the anode side separator 10, and the through holes 32 and 33 of the seal member 30. As a result, in a state in which the unit cell U is formed, the fuel supply port 12 (through holes 24 and 32) communicates with the through hole 41, and the fuel discharge port 13 (through holes 25 and 33) communicates with the through hole 42.

[0041] Furthermore, in a state where the unit cell U is formed, the peripheral portion of the electrolyte membrane EF is provided with through holes 43, 44 at positions corresponding to the oxidant supply port 22 (corresponding to the through hole 14 of the anode side separator 10), the oxidant discharge port 23 (corresponding to the through hole 15 of the anode side separator 10) provided in the cathode side separator 20, and the through holes 34, 35 of the seal member 30. As a result, in a state where the unit cell U is formed, the oxidant supply port 22 (through holes 14, 34) communicates with the through hole 43, and the oxidant discharge port 23 (through holes 15, 35) communicates with the through hole 44. Furthermore, in a state where the unit cell U is formed, the electrolyte membrane EF is provided with an insertion hole 45 formed to insert the bolt B of the holder H.

[0042] The anode electrode layer AE and the cathode electrode layer CE as electrode layers are mainly composed of carbon carrying catalyst particles (carried carbon), and are formed in layers on the surface of the central portion of the electrolyte membrane EF, as shown in Fig. 7. Examples of the catalyst particles include platinum (Pt), platinum alloys, and non-platinum-based metal compounds. Examples of the platinum alloy include alloys of platinum and at least one metal selected from the group consisting of ruthenium (Ru), palladium (Pd), nickel (Ni), molybdenum (Mo), iridium (Ir), iron (Fe), and the like.

[0043] Here, the anode electrode layer AE and the cathode electrode layer CE formed in layers are formed so as to have a thickness slightly larger than the thickness of the seal member 30. In addition, the anode electrode layer AE and the cathode electrode layer CE formed in layers have outer dimensions slightly smaller than the size of the accommodation portion 31 of the seal member 30.

[0044] 7, the surface side of each of the anode electrode layer AE and the cathode electrode layer CE is covered with carbon cloth (or carbon paper) CC as a diffusion layer formed from conductive fibers. The carbon cloth CC diffuses the formic acid supplied to the anode electrode layer AE and the air supplied to the cathode electrode layer CE, and efficiently supplies electricity generated by the electrode reaction to the anode-side separator 10 and the cathode-side separator 20.

[0045] That is, since the carbon cloth CC is fibrous, the fibers are electrically conductive, so that the supplied formic acid and air are uniformly diffused. Also, since the carbon cloth CC is electrically conductive, the generated electricity can be efficiently passed through the anode-side separator 10 and the cathode-side separator 20.

[0046] 2, the heater 50 is attached to the surface of the anode-side separator 10 opposite to the surface on which the fuel supply flow path 11 is formed, and its operation is controlled by the control device 100 to heat formic acid, which is a liquid fuel, flowing through the fuel supply flow path 11 of the anode-side separator 10. As shown in FIG. 8, the heaters 50 in this example are disposed in the upstream, midstream, and downstream portions of the serpentine fuel supply flow path 11, and heat the formic acid flowing from the fuel supply port 12 to the fuel discharge port 13. As a result, when formic acid is supplied to the anode electrode layer AE of the MEA 40, the temperature of the formic acid flowing through the fuel supply flow path 11 is heated to and maintained in a temperature range suitable for the electrode reaction, and the electrode reaction in the MEA 40 is promoted, in other words, the power generation efficiency can be improved.

[0047] The heater 50 is, for example, a planar heater, and is divided along the fuel supply flow path 11. Specifically, the heater 50 is divided for each bent portion 11a of the fuel supply flow path 11, that is, for each bent portion 11a that changes the flow direction of formic acid by 90 degrees or more (180 degrees in this example) with respect to the straight portion 11b in the fuel supply flow path 11.

[0048] The heater 50 is divided into a first heater 51 arranged corresponding to the upstream portion of the fuel supply flow path 11, a second heater 52 arranged corresponding to the midstream portion of the fuel supply flow path 11, and a third heater 53 arranged corresponding to the downstream portion of the fuel supply flow path 11. The first heater 51, the second heater 52, and the third heater 53 forming the heater 50 are arranged from the fuel supply port 12 side of the fuel supply flow path 11 along the fuel discharge port 13 so that the amount of heat input per unit area to formic acid gradually decreases.

[0049] For this reason, the operation of the first heater 51 is controlled by the control device 100 so that the amount of heat input per unit area to formic acid is the largest among the heaters 50. The operation of the second heater 52 is controlled by the control device 100 so that the amount of heat input is smaller than that of the first heater 51. The operation of the third heater 53 is controlled by the control device 100 so that the amount of heat input is the smallest among the heaters 50.

[0050] As a result, in this example, the first heater 51 heats the low-temperature formic acid supplied from the supply tank T with the largest heat input in the upstream portion of the fuel supply flow path 11. The second heater 52 heats the formic acid heated and increased in temperature by the first heater 51 with a medium heat input in the midstream portion of the fuel supply flow path 11. The third heater 53 heats the formic acid heated and further increased in temperature by the first heater 51 and the second heater 52 with the smallest heat input in the downstream portion of the fuel supply flow path 11.

[0051] Here, since the formic acid supplied to the upstream portion is supplied from the supply tank T as described above, its temperature is lower than the temperature range suitable for the electrode reaction. The temperature of the formic acid supplied increases in the order of the midstream portion and the downstream portion. For this reason, in order to promote the electrode reaction early in the MEA 40 facing the upstream portion of the fuel supply flow path 11, it is necessary to heat the formic acid and increase the temperature early so that the formic acid is brought into the temperature range suitable for the electrode reaction early.

[0052] 8, the first heater 51 in this example has a first high-temperature heater 51a arranged at the most upstream position and a first low-temperature heater 51b arranged downstream of the most upstream position. The first high-temperature heater 51a is arranged at a position closest to the fuel supply port 12, and is controlled by the control device 100 to maximize the heat input in order to quickly heat the low-temperature formic acid supplied from the supply tank T. In addition, the heat input of the first low-temperature heater 51b is controlled by the control device 100 to be smaller than the heat input of the first high-temperature heater 51a and larger than the heat input of the second heater 52.

[0053] In the midstream section, the formic acid heated by the first heater 51 in the upstream section passes through the bent section 11a (the bent section 11a on the upstream side) connecting the upstream section and the midstream section, and passes through the bent section 11a (the bent section 11a on the downstream side) connecting the midstream section and the downstream section via the straight section 11b in the midstream section. That is, the formic acid flowing in the midstream section is affected by the pressure loss generated in the bent section 11a on the upstream side and the bent section 11a on the downstream side. For this reason, the flow rate of the formic acid flowing in the midstream section tends to decrease relatively.

[0054] For this reason, in the formic acid flowing through the midstream portion, heat transfer is likely to occur, for example, toward the anode-side separator 10. Therefore, in order to maintain the temperature of the formic acid flowing through the midstream portion in a temperature range suitable for the electrode reaction, the amount of heat input can be made different between the upstream and downstream of the midstream portion.

[0055] Specifically, the second heater 52 in this example has a second high-temperature heater 52a arranged upstream of the midstream section and a second low-temperature heater 52b arranged downstream, as shown in Fig. 8. The second high-temperature heater 52a is arranged at a position close to the upstream bent section 11a, and is controlled by the control device 100 to increase the heat input in order to heat the formic acid supplied from the upstream section through the upstream bent section 11a. The second low-temperature heater 52b is arranged at a position close to the downstream bent section 11a. The heat input of the second low-temperature heater 52b is controlled by the control device 100 to be smaller than the heat input of the second high-temperature heater 52a and larger than the heat input of the third heater 53.

[0056] The control device 100 is a microcomputer whose main components include a CPU, a ROM, a RAM, an interface, etc. The control device 100 mainly controls the operation of the heaters 50, that is, the first heater 51, the second heater 52, and the third heater 53. Specifically, the control device 100 controls the operating current I supplied to each of the first heater 51, the second heater 52, and the third heater 53 (see FIG. 1).

[0057] 2, the unit cell U of this example is formed by sequentially stacking in the horizontal direction an anode-side separator 10 to which a heater 50 is attached, a sealing member 30, an MEA 40, another sealing member 30, and a cathode-side separator 20. Here, when forming the unit cell U, it is possible to hermetically bond each member to each other, as necessary, using, for example, a conductive adhesive.

[0058] A plurality of the formed unit cells U are stacked according to the required output to constitute a fuel cell stack S. In the fuel cell stack S configured in this manner, the fuel supply port 12 and the fuel discharge port 13 of each anode side separator 10 are in communication with each other between the stacked unit cells U via the through holes 24, 25, etc. of the cathode side separator 20. In the fuel cell stack S, the oxidant supply port 22 and the oxidant discharge port 23 of each cathode side separator 20 are in communication with each other between the stacked unit cells U via the through holes 14, 15, etc. of the anode side separator 10.

[0059] In the following description, the communication passage formed by the fuel supply port 12 of the anode side separator 10 and the through hole 24 of the cathode side separator 20, through which formic acid flows, is referred to as the "fuel side manifold." Also, the communication passage formed by the oxidant supply port 22 of the cathode side separator 20 and the through hole 14 of the anode side separator 10, through which air flows, is referred to as the "oxidant side manifold."

[0060] (3. Operation of fuel cell system 1) Next, we will explain the operation of the above-mentioned fuel cell system 1. In the fuel cell system 1, formic acid pressurized by the fuel pump P1 from the supply tank T is supplied to the anode electrode layer AE of each unit cell U via the fuel-side manifold. In the fuel cell FC, air from the blower P2 is supplied to the cathode electrode layer CE of each unit cell U via the oxidant-side manifold.

[0061] That is, in each unit cell U, formic acid supplied via the fuel supply port 12 of the anode side separator 10 flows through the fuel supply flow path 11 toward the fuel discharge port 13. As a result, formic acid, which is a liquid fuel, is supplied to the anode electrode layer AE of the MEA 40. Also, in each unit cell U, air supplied via the oxidant supply port 22 of the cathode side separator 20 flows through the oxidant supply flow path 21 toward the oxidant discharge port 23. As a result, air, which is an oxidant (oxidant gas) flowing through the oxidant supply flow path 21, is supplied to the cathode electrode layer CE of the MEA 40.

[0062] As is well known, the MEA 40 of each unit cell U generates electricity by an electrode reaction between formic acid (HCOOH) and air (oxygen (O2)). Specifically, in this example, the electrolyte membrane EF of the MEA 40 is formed of an ion exchange membrane that selectively allows cations to pass through. Therefore, in the MEA 40, electrode reactions occur according to the following chemical reaction formulas 1 and 2. Anode electrode layer AE: HCOOH → 2H + +2e - +CO2…Chemical reaction formula 1 Cathode electrode layer CE: 2H + +2e - +(1 / 2)O2→H2O … Chemical reaction equation 2

[0063] In the fuel cell system 1 of this embodiment, the control device 100 controls the heat input of each of the heaters 50 assembled to the anode-side separator 10, that is, the first heater 51 arranged corresponding to the upstream portion of the fuel supply flow passage 11 of the anode-side separator 10, the second heater 52 arranged corresponding to the midstream portion, and the third heater 53 arranged corresponding to the downstream portion. More specifically, as shown in Fig. 9, the control device 100 controls the heat input of each of the heaters 50 so that the heat input gradually decreases in the order of the first high-temperature heater 51a forming the first heater 51, the first low-temperature heater 51b, the second high-temperature heater 52a forming the second heater 52, the second low-temperature heater 52b, and the third heater 53. Note that Fig. 9 indicates that the heat input decreases as the darkness of the matte finish decreases.

[0064] That is, the control device 100 controls the magnitude of the operating current I supplied to each of the first high-temperature heater 51a, the first low-temperature heater 51b, the second high-temperature heater 52a, the second low-temperature heater 52b, and the third heater 53 so that the operating current I decreases in this order along the fuel supply flow path 11, in other words, in the flow direction of formic acid from the fuel supply port 12 toward the fuel exhaust port 13. As a result, the low-temperature formic acid that has reached the fuel supply flow path 11 from the supply tank T via the fuel supply port 12 is first heated (raised in temperature) to a temperature range suitable for the electrode reaction early by the first high-temperature heater 51a, which has the largest heat input.

[0065] Next, the temperature of the formic acid flowing through the fuel supply flow passage 11 is maintained in a temperature range suitable for the electrode reaction by being heated by the first low-temperature heater 51b, the second high-temperature heater 52a, and the second low-temperature heater 52b in order of decreasing heat input. Then, the temperature of the formic acid that has flowed to the downstream part of the fuel supply flow passage 11 is maintained in a temperature range suitable for the electrode reaction by being heated by the third heater 53 which has the smallest heat input, in other words, which has the smallest current supplied thereto, and is discharged from the fuel outlet 13 to the collection tank.

[0066] Thus, in the fuel cell system 1, the formic acid liquid fuel supplied from the supply tank T to the fuel supply flow passage 11 of the anode-side separator 10 is maintained by the heater 50 in a temperature range suitable for the electrode reaction in the MEA 40. Therefore, in the anode electrode of the MEA 40, i.e., the anode electrode layer AE, the electrode reaction according to the above chemical reaction formula 1 occurs uniformly over the entire surface facing the upstream, midstream, and downstream portions of the fuel supply flow passage 11. As a result, the fuel cell stack S of the fuel cell system 1 can generate electric power efficiently.

[0067] As can be understood from the above description, the fuel cell system 1 of this embodiment can include a heater 50 that is controlled by the control device 100 and heats formic acid in the fuel supply flow path 11 of the anode-side separator 10. Therefore, by controlling the operating current I supplied by the control device 100 to the heater 50, the formic acid flowing through the fuel supply flow path 11 can be heated and the temperature of the formic acid can be heated and maintained in a temperature range suitable for the electrode reaction in the MEA 40.

[0068] Furthermore, in the fuel cell system 1, the heater 50 can be divided into a first heater 51 (first high-temperature heater 51a and first low-temperature heater 51b), a second heater 52 (second high-temperature heater 52a and second low-temperature heater 52b), and a third heater 53, and these heaters can be arranged along the fuel supply flow path 11. Then, the control device 100 can control the operating current I for each of the heaters arranged from the fuel supply port 12 toward the fuel discharge port 13 so that the amount of heat input gradually decreases.

[0069] This allows the temperature of the formic acid flowing through the fuel supply flow passage 11 to be efficiently heated to and maintained in a temperature range suitable for the electrode reaction, thereby reducing unnecessary power consumption. In addition, since the temperature of the formic acid can be efficiently heated to and maintained in a temperature range suitable for the electrode reaction, the electrode reaction can be promoted and uniformly generated in the MEA 40. Therefore, the fuel cell system 1 can efficiently generate power.

[0070] (4. First alternative example) In the above-described embodiment, the control device 100 controls the operating current I supplied to the heaters 50, i.e., the first heater 51, the second heater 52, and the third heater 53 arranged in order from the fuel supply port 12 (upstream side) of the fuel supply flow passage 11 of the anode-side separator 10 along the fuel discharge port 13 (downstream side) so as to decrease in order. As a result, the first heater 51 closest to the fuel supply port 12 heats the formic acid to a temperature suitable for the electrode reaction in the MEA 40 with the greatest heat input. Meanwhile, the second heater 52 and the third heater 53, whose heat inputs are gradually reduced, maintain the temperature of formic acid in a temperature range suitable for the electrode reaction.

[0071] In the unit cell U forming the fuel cell stack S, when formic acid, which is a liquid fuel, is supplied to the anode electrode layer AE and air is supplied to the cathode electrode layer CE, the above-mentioned electrode reaction occurs to generate electricity. The electric current generated by the power generation is collected by the anode-side separator 10 having a current collecting function and output to the outside.

[0072] Here, the current generated by the electrode reaction generates Joule heat when it is passed through the anode-side separator 10 in association with current collection. The Joule heat depends on the magnitude of the generated power (hereinafter referred to as the "amount of generated current"), and increases as the amount of generated current increases. That is, the more prominent the location of the electrode reaction, the greater the amount of generated current, and as a result, a large amount of Joule heat is generated. The generated Joule heat heats the anode-side separator 10, and ultimately the formic acid flowing through the fuel supply channel 11.

[0073] As shown in FIG. 10, when the flow rate of formic acid flowing through the fuel supply passage 11 is constant without heating, the location where the electrode reaction in the single cell U is prominent, in other words, the location where the amount of generated current is large, tends to be larger the closer to the fuel supply port 12 in the anode-side separator 10, and smaller the closer to the fuel outlet 13. In other words, when an electrode reaction occurs, the amount of generated current is large in the upstream portion of the fuel supply passage 11 in the anode-side separator 10, and as a result, the amount of generated Joule heat is large. Furthermore, the amount of generated current is smaller in the midstream portion of the fuel supply passage 11 than in the upstream portion, and as a result, the amount of generated Joule heat is smaller than in the upstream portion. Furthermore, the amount of generated current is smaller in the downstream portion of the fuel supply passage 11 than in the midstream portion, and as a result, the amount of generated Joule heat is smaller than in the midstream portion.

[0074] For this reason, in a state in which the electrode reaction continues without formic acid being actively heated, the formic acid flowing through the fuel supply flow passage 11 of the anode-side separator 10 is likely to be heated by Joule heat generated in the upstream portion. On the other hand, in the midstream and downstream portions of the fuel supply flow passage 11, particularly in the vicinity of the fuel outlet 13, the amount of Joule heat generated is small, and therefore the formic acid is less likely to be heated by Joule heat.

[0075] Therefore, in the first variant, the control device 100 takes into consideration the difference in the magnitude of Joule heat generated corresponding to the position of the fuel supply passage 11, specifically, the upstream, midstream, and downstream portions, and controls by increasing or decreasing the operating current I supplied to the heater 50 according to the following equation 1. I = Ip - Ij ... Equation 1 Here, "Ip" in the above formula 1 represents the first current, and as in the present example described above, is a current that is determined according to the position of each heater 50 arranged along the fuel supply flow path 11. That is, the first current Ip is a current that is determined so as to become smaller in the order of the first high-temperature heater 51a, the first low-temperature heater 51b, the second high-temperature heater 52a, the second low-temperature heater 52b, and the third heater 53 along the fuel supply flow path 11, in other words, in the flow direction of formic acid from the fuel supply port 12 to the fuel exhaust port 13.

[0076] In addition, "Ij" in the above formula 1 represents a second current, which is a current determined based on the generated Joule heat. The second current Ij is determined by adding a third current Ij1 determined depending on the temperature of the formic acid liquid fuel and a fourth current Ij2 determined depending on the Joule heat in the area of ​​the heater, as shown in the following formula 2. Ij=Ij1+Ij2 …Equation 2 10, the third current Ij1 in the above formula 2 is a current that is determined depending on the reference temperature RT, where RT is the temperature of formic acid acquired at a predetermined position P of the fuel supply flow path 11. That is, the third current Ij1 is determined to be a larger current as the reference temperature RT is larger, and is determined to be a smaller current as the reference temperature RT is smaller.

[0077] Moreover, the fourth current Ij2 in the above formula 2 is a current that is determined depending on, for example, a value obtained by integrating the Joule heat generated in the area of ​​each of the first high-temperature heater 51a, the first low-temperature heater 51b, the second high-temperature heater 52a, the second low-temperature heater 52b, and the third heater 53 that are arranged along the fuel supply flow path 11. That is, the larger the area or the larger the Joule heat generated, the larger the current is determined, and the smaller the area or the smaller the Joule heat generated, the smaller the current is determined.

[0078] Therefore, in the first modified example, the control device 100 determines the first current Ip, which decreases in order according to the arrangement of the first high-temperature heater 51a and the first low-temperature heater 51b forming the first heater 51, the second high-temperature heater 52a and the second low-temperature heater 52b forming the second heater 52, and the third heater 53, in the same manner as in the above-described present example. The control device 100 also determines the second current Ij using the third current Ij1 based on the reference temperature RT and the fourth current Ij2 based on Joule heat according to the area of ​​each heater 50. Then, the control device 100 determines the operating current I by subtracting the second current Ij from the first current Ip according to the above formula 1.

[0079] Here, the operation of the first modified example will be described by taking as an example the first high-temperature heater 51a of the first heater 51 arranged at the most upstream of the fuel supply flow path 11 and the third heater 53 arranged at the downstream part of the fuel supply flow path 11. The first high-temperature heater 51a of the first heater 51 needs to heat the low-temperature formic acid supplied from the supply tank T as early as possible, as in the above-mentioned embodiment. For this reason, for example, immediately after the fuel cell system 1 starts operating, the control device 100 determines the first current Ip to be a large current. On the other hand, for example, immediately after the fuel cell system 1 starts operating, the electrode reaction is not stable, the generated Joule heat is small, and the reference temperature RT is also low. Therefore, the control device 100 determines the second current Ij to be a small current.

[0080] Therefore, immediately after the fuel cell system 1 starts operating, the control device 100 determines the operating current I to be supplied to the first high-temperature heater 51a by subtracting the small second current Ij from the large first current Ip in accordance with the above formula 1. That is, immediately after the fuel cell system 1 starts operating, the first current Ip is mainly supplied to the first high-temperature heater 51a as the operating current I, so that the first high-temperature heater 51a heats the formic acid with a large amount of heat input, and increases the temperature of the formic acid to a temperature range suitable for the electrode reaction.

[0081] For example, as time passes after the fuel cell system 1 starts operating, the electrode reaction becomes prominent at the location corresponding to the first high-temperature heater 51a. As a result, a large amount of Joule heat is generated at the location corresponding to the first high-temperature heater 51a. As time passes after the fuel cell system 1 starts operating, the formic acid is heated by the heat input from the first high-temperature heater 51a, and the reference temperature RT at the predetermined position P also rises.

[0082] Therefore, the second current Ij calculated according to the above formula 2 is determined to be a large current due to the increase in the third current Ij1 and the fourth current Ij2. As a result, the control device 100 determines the operating current I by subtracting the large second current Ij from the first current Ip according to the above formula 1. That is, in the first high-temperature heater 51a, the generated Joule heat is large and the formic acid is heated by the Joule heat, so that the heat input can be reduced. That is, in this case, the operating current I supplied to the first high-temperature heater 51a can be reduced compared to the case of the above-mentioned embodiment.

[0083] On the other hand, for the third heater 53, as in the present embodiment described above, the formic acid is heated by the first heater 51 and the second heater 52, and therefore the required heat input is small. However, in the downstream portion of the fuel supply passage 11, for example, immediately after the fuel cell system 1 starts operating or even after some time has passed since the start of operation, the electrode reaction is relatively less prominent there than in the upstream portion, and therefore the amount of Joule heat generated is small. That is, for example, even if the third heater 53 has an area larger than that of the first high-temperature heater 51a, the amount of Joule heat generated is small, and therefore the second current Ij determined according to the above formula 2 is small.

[0084] Therefore, the control device 100 determines the operating current I to be supplied to the third heater 53 by subtracting the small second current Ij from the first current Ip determined in the same manner as in the present example described above, according to the above formula 1. That is, the third heater 53 disposed downstream of the fuel supply passage 11 is mainly supplied with the first current Ip as the operating current I, so that the formic acid is heated with the same heat input as in the present example described above, and the temperature of the formic acid is maintained in a temperature range suitable for the electrode reaction. That is, in the first modified example, the operating current I supplied to the third heater 53 can be slightly reduced compared to the present example described above.

[0085] Therefore, in the first modified example, the effect of the generated Joule heat can be taken into consideration, and therefore the operating current I can be reduced in accordance with the generated Joule heat, thereby realizing energy saving. Also in the first modified example, as in the above-described present example, it is possible to prevent the heater 50 from wasting power. Also in the first modified example, the formic acid, which is the liquid fuel supplied to the anode electrode layer AE, can be maintained in a temperature range suitable for the electrode reaction, so that the fuel cell FC can generate power efficiently.

[0086] (5.Second alternative example) In the present example and the first modified example described above, the heater 50 is arranged along the fuel supply flow passage 11 formed in the anode-side separator 10, with the first heater 51 in the upstream portion, the second heater 52 in the midstream portion, and the third heater 53 in the downstream portion. However, when dividing the heater 50, it is not limited to dividing according to the upstream portion, midstream portion, and downstream portion of the fuel supply flow passage 11. For example, as shown in Fig. 11, the heater 50 can be divided for each point with large curvature in the bent portion 11a of the fuel supply flow passage 11.

[0087] (6. Third alternative example) In the present example, the first modified example, and the second modified example described above, the fuel supply flow path 11 formed in the anode-side separator 10 has a uniform flow path width from the fuel supply port 12 to the fuel discharge port 13. However, as shown in Fig. 12, the fuel supply flow path 18 formed in the anode-side separator 10 can have a flow path width changing portion 18c where the flow path width changes between the fuel supply port 12 and the fuel discharge port 13. In addition, the fuel supply flow path 18 can have a branching portion 18d where the fuel supply flow path 18 branches into a plurality of flow paths. The fuel supply flow path 18 is also formed in a serpentine shape, and has a bent portion 18a and a straight portion 18b.

[0088] In the case of the fuel supply flow passage 18 having the flow passage width change portion 18c, as shown in FIG. 13, the heater 60 can be divided based on the flow passage width change portion 18c. In this case, the heater 60 is divided into a first heater 61 arranged in the upstream portion of the fuel supply flow passage 18, a second heater 62 arranged in the midstream portion upstream (on the side where the flow passage width is larger) of the flow passage width change portion 18c, a third heater 63 arranged downstream (on the side where the flow passage width is smaller) of the flow passage width change portion 18c, and a fourth heater 64 arranged in the downstream portion of the fuel supply flow passage 18. Note that FIG. 13 also shows that the lighter the darkness of the matte finish, the smaller the heat input amount. Therefore, the control device 100 controls the operation of the heater 60 (more specifically, the operating current I) according to the required heat input amount along the fuel supply flow passage 18, similar to the heater 50 in the present embodiment and the first modified embodiment described above.

[0089] Here, when the fuel supply flow passage 18 is formed in the anode-side separator 10, the heater 70 can be divided based on the branching portion 18d as shown in FIG. 14. In this case, the heater 70 is divided into a first heater 71 arranged corresponding to the branching portion 18d near the fuel supply port 12 of the fuel supply flow passage 18 (on the right side in FIG. 14), a second heater 72 arranged adjacent to the first heater 71, and a third heater 73 arranged corresponding to the branching portion 18d near the fuel outlet 13 of the fuel supply flow passage 18 (on the left side in FIG. 14). Note that FIG. 14 also shows that the lighter the density of the matte finish, the smaller the heat input. Therefore, the control device 100 controls the operation of the heater 70 (more specifically, the operating current I) according to the required heat input along the fuel supply flow passage 18, similar to the heater 50 in the present embodiment and the first modified embodiment described above.

[0090] Furthermore, when the fuel supply flow passage 18 is formed in the anode-side separator 10, as shown in Fig. 15, it is also possible to divide the fuel supply flow passage 18 into a first heater 81 arranged in the upstream part of the fuel supply flow passage 18 according to the distance L1 from the fuel supply port 12, a second heater 82 arranged from the upstream part to the downstream part of the fuel supply flow passage 18, and a third heater 83 arranged in the downstream part of the fuel supply flow passage 18 according to the distance L1 from the fuel exhaust port 13. Note that Fig. 15 also shows that the lighter the darkness of the matte finish, the smaller the heat input. Therefore, in this case as well, the control device 100 controls the operation of the heater 80 (more specifically, the operating current I) according to the required heat input along the fuel supply flow passage 18, similarly to the heater 50 in the present example and the first modified example described above. [Explanation of symbols]

[0091] 1... fuel cell system, 10... anode side separator, 11... fuel supply flow path, 11a... bent portion, 11b... straight portion, 12... fuel supply port, 13... fuel exhaust port, 14, 15... through hole, 16... insertion hole, 17... electrode portion, 18... fuel supply flow path, 18a... bent portion, 18b... straight portion, 18c... flow path width change portion, 18d... branch portion, 20... cathode side separator, 20a... opposing surface, 20b ...back surface, 20c...discharge portion, 21...oxidant supply flow path, 22...oxidant supply port, 23...oxidant discharge port, 24, 25...through hole, 26...insertion hole, 27...electrode portion, 30...sealing member, 31...accommodation portion, 32-35...through hole, 36...insertion hole, 40...MEA (electrode structure), 41...through hole, 41-44...through hole, 45...insertion hole, 50...heater, 51...first heater, 51a...first high-temperature heater heater, 51b...first low temperature heater, 52...second heater, 52a...second high temperature heater, 52b...second low temperature heater, 53...third heater, 60...heater, 61...first heater, 62...second heater, 63...third heater, 64...fourth heater, 70...heater, 71...first heater, 72...second heater, 73...third heater, 80...heater, 81...first heater, 82...second heater, 83...third heater, AE...anode electrode layer, CE...cathode electrode layer, EF...electrolyte membrane, CC...carbon cloth, FC...direct formic acid fuel cell (fuel cell), S...fuel cell stack, U...single cell, H...holder, B...bolt, P1...fuel pump, P2...blower, T...supply tank, L1...distance (from fuel supply port), L2...distance (from fuel exhaust port), P...predetermined position, RT...reference temperature

Claims

1. an electrode structure having an electrolyte membrane, an anode electrode, and a cathode electrode; an anode-side separator having a fuel supply flow path for supplying a liquid fuel to the anode; a cathode-side separator having an oxidant supply flow path for supplying an oxidant to the cathode electrode, the electrode structure being disposed between a pair of the anode-side separator and the cathode-side separator to form a single cell, and generating power through an electrode reaction in the electrode structure; a heater that heats the liquid fuel in the fuel supply flow channel of the anode-side separator; A control device that controls the operation of the heater, The heater is divided and disposed in the fuel supply passage, The control device includes: heating the liquid fuel flowing through the fuel supply flow passage by controlling heating by the heater so that a temperature of the liquid fuel on a supply side of the liquid fuel to the fuel supply flow passage is within a temperature range suitable for the electrode reaction; and When the liquid fuel on the supply side is heated to a temperature range suitable for the electrode reaction and flows through the fuel supply flow path, a fuel cell system that controls operation of the heater so that an amount of heat input per unit area from the heater to the liquid fuel gradually decreases along a liquid fuel discharge side from the supply side of the fuel supply flow path.

2. The fuel supply passage is formed in a serpentine shape having a straight portion and a bent portion, 2. The fuel cell system according to claim 1, wherein the heater is divided for each bent portion in the fuel supply flow path.

3. 3. The fuel cell system according to claim 2, wherein the bent portion changes the flow direction of the liquid fuel by 90 degrees or more with respect to a straight portion of the fuel supply channel.

4. an electrode structure having an electrolyte membrane, an anode electrode, and a cathode electrode; an anode-side separator having a fuel supply flow path for supplying a liquid fuel to the anode; a cathode-side separator having an oxidant supply flow path for supplying an oxidant to the cathode electrode, the electrode structure being disposed between a pair of the anode-side separator and the cathode-side separator to form a single cell, and generating power through an electrode reaction in the electrode structure; a heater that heats the liquid fuel in the fuel supply flow channel of the anode-side separator; A control device that controls the operation of the heater, The heater is divided and disposed in the fuel supply passage, The control device includes: heating the liquid fuel flowing through the fuel supply flow passage by controlling heating by the heater so that a temperature of the liquid fuel on a supply side of the liquid fuel to the fuel supply flow passage is within a temperature range suitable for the electrode reaction; and A fuel cell system that controls the operation of each of the divided heaters based on the position of each of the divided heaters relative to the fuel supply flow path and Joule heat corresponding to the amount of current generated in conjunction with power generation by the electrode reaction in the electrode structure.

5. The control device includes: The operating current supplied to each of the divided heaters is controlled, 5. The fuel cell system according to claim 4, wherein the operating current supplied to each of the heaters is increased or decreased depending on the magnitude of the Joule heat in each of the divided areas of the heater.

6. The control device further comprises: referring to a temperature of the liquid fuel flowing at a predetermined position in the fuel supply passage, The fuel cell system according to claim 5 , wherein the operating current is determined in response to the referenced temperature.

7. 7. The fuel cell system according to claim 1, wherein the heater is provided in the anode side separator.

8. 8. The fuel cell system according to claim 1, wherein the liquid fuel is formic acid (HCOOH).

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