JP3609742B2 - Polymer electrolyte fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention particularly relates to an improvement in a polymer electrolyte fuel cell in which a heat medium chamber is provided at an end of the fuel cell.
[0002]
[Prior art]
A polymer electrolyte fuel cell includes a solid polymer electrolyte membrane such as a fluororesin ion exchange membrane as an electrolyte, and a fuel electrode is joined to one surface of the electrolyte membrane, and an air electrode is joined to the other surface. A cell is formed, and further, a fuel chamber in which fuel gas flows on the fuel electrode side and an air chamber in which air flows on the air electrode side are provided as unit cells, and a plurality of unit cells are stacked to form a laminate. The end plates are respectively attached to both ends and hermetically tightened with bolts or the like to be integrated.
[0003]
In the polymer electrolyte fuel cell configured as described above, a fuel gas (reformed gas obtained by reforming a hydrocarbon-based raw fuel into a hydrogen-rich gas) is supplied to the fuel chamber, and taken into the air chamber from outside air. The air is supplied, and the hydrogen gas in the reformed gas and the oxygen gas in the air undergo an electrochemical reaction through the electrolyte membrane to generate electric power and water. At this time, since the electrochemical reaction is an exothermic reaction, cooling water is supplied to the polymer electrolyte fuel cell to cool it.
[0004]
The polymer electrolyte fuel cell operates at an appropriate temperature (for example, 80 ° C.), but the unit cell at the end tends to be lower in temperature than the other unit cells because it is in contact with the metal end plate. When the temperature of the unit cell is lowered, not only the power generation performance is lowered, but CO contained in a minute amount in the reformed gas adheres to the electrolyte membrane and is poisoned. For this reason, a polymer electrolyte fuel cell is known in which a heating medium chamber is provided between the air chamber and the end plate in the end unit cell so as to raise the temperature of the end unit cell (for example, a special type). (Kaihei 11-97048).
[0005]
[Problems to be solved by the invention]
In the conventional polymer electrolyte fuel cell, for example, a reformed gas is used as a heat medium supplied to the heat medium chamber. In this case, only a part of the reformed gas is used, and the following is performed. The problem was pointed out.
(1) Since part of the reformed gas is passed through the heat medium chamber, the heat exchange efficiency to the unit cell at the end is low.
(2) The reformed gas that has passed through the heat medium chamber is difficult to be used for power generation and is discharged from the fuel cell, so the reaction efficiency is low.
(3) The reformed gas supplied to the fuel cell is usually supplied with the reformed gas directly by the reformer, so that the temperature is high and the fuel cell temperature is likely to rise abnormally, resulting in a short life.
[0006]
Therefore, the present invention provides a heat diffusion plate between the heat medium chamber and the end unit cell, and allows the entire amount of the reformed gas to pass through the heat medium chamber to increase the heat exchange efficiency to the end unit cell. An object of the present invention is to provide a polymer electrolyte fuel cell that is configured to improve the reaction efficiency by supplying the reformed gas that has passed therethrough to each unit cell. In addition, by providing a cooling water flow passage inside the heat diffusion plate or adjacent to the heat medium chamber, the temperature of the reformed gas is lowered to prevent an abnormal rise in the temperature of the fuel cell and the temperature of the unit cell at the end is raised. The purpose is to adjust.
[0007]
[Means for Solving the Problems]
As a specific means for achieving the above object, the present invention provides a fuel gas distribution on the fuel electrode side of a cell formed by joining a fuel electrode to one surface of a solid polymer electrolyte membrane and an air electrode to the other surface. fuel chamber, by disposing the air chamber unit cell and without the air flows to the air electrode side, a first end plate on the side of the fuel chamber of the stack of superposed multiple the unit cell is the end surface of the air chambers at a second end plate solid high polymer fuel cell and integrated tightened against each side the end surfaces, and said second end plate and said second end plate side end unit cell of and Netsunakadachishitsu provided between, together with and a thermal diffusion plate provided between said heating medium chamber and a unit cell of said end portions, supplying the total amount of the fuel gas to the heating medium chamber, wherein solid polymer fuel collector, characterized by supplying the fuel gas after Netsunakadachishitsu pass into the fuel chamber of each unit cell The the gist.
Also, a configuration in which a cooling water flow passage is provided in the heat diffusion plate, a configuration in which a cooling water flow passage is provided between the heat medium chamber and the end plate,
A configuration in which cooling water discharged from the fuel cell circulates in the cooling water flow passage;
A configuration in which an unreacted hydrogen gas flow passage discharged from the fuel cell is provided between the cooling water flow passage and the end plate;
A configuration in which the heat medium chamber and the cooling water flow passage are partitioned by a water permeable member,
It is characterized by.
[0008]
With such a configuration, the following effects can be expected in the present invention.
(1) By passing the entire amount of reformed gas through the heat medium chamber and interposing a material (heat diffusion plate) with high heat conductivity between the heat medium chamber and the end unit cell, The heat exchange efficiency for the unit cell is improved.
(2) The reaction efficiency of the fuel cell is improved by supplying the reformed gas that has passed through the heat medium chamber to each unit cell.
(3) By providing the cooling water flow passage in the heat diffusion plate or adjacent to the heat medium chamber, it is possible to cool the reformed gas and prevent the fuel cell temperature from rising abnormally.
(4) The reformed gas can be humidified by interposing a water-permeable member between the heat medium chamber and the cooling water flow passage.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the polymer electrolyte fuel cell according to the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a first embodiment, wherein 1 is a unit cell, and a cell formed by joining a fuel electrode on one surface of a solid polymer electrolyte membrane and an air electrode on the other surface as in the prior art. A fuel chamber through which fuel gas flows is arranged on the fuel electrode side of the cell, and an air chamber through which air circulates on the air electrode side. Reference numeral 2 denotes a laminated body, which is formed by stacking a large number of the unit cells 1, metal end plates 3 and 4 are applied to both ends of the laminated body 2, and tightened with bolts (not shown) to be integrated into a fuel cell 5A is formed.
[0010]
In the fuel cell 5A, a heat medium chamber 6 is provided between one end plate 4 and a unit cell 1A at the end on the end plate 4 side, and between the heat medium chamber 6 and the unit cell 1A, A thermal diffusion plate 7 that is a partition plate having high thermal conductivity is interposed. Further, the entire amount of fuel gas, that is, hydrogen-rich reformed gas, passes through the heat medium chamber 6 and is supplied to the fuel chambers of all unit cells after the passage.
[0011]
The reformed gas is supplied after reforming the raw fuel gas such as city gas with a reformer (not shown), but the temperature is about 120 ° C., and this reformed gas passes through the heat medium chamber 6. When heating, the temperature inside the heat medium chamber 6 is raised. Since the heat diffusion plate 7 is in contact with the heat medium chamber 6, heat is transferred to the adjacent unit cell 1 </ b> A via the heat diffusion plate 7. Therefore, the unit cell 1A at the end can be heated to a predetermined temperature in a short time, and can be maintained at the predetermined temperature by preventing a temperature drop during power generation.
[0012]
In the power generation in the fuel cell 5A, the reformed gas is supplied to the fuel chamber of each unit cell 1 and air is supplied to the air chamber, and hydrogen gas in the reformed gas and oxygen gas in the air are supplied. Is caused by causing an electrochemical reaction through the electrolyte membrane in the cell.
[0013]
Since the electrolyte membrane is required to be moderately wet during power generation, the wet state of the electrolyte membrane is usually maintained by supplying the reformed gas with humidification. Further, since the fuel cell 5A generates heat as power is generated, the cooling water is supplied from the water tank (not shown) to the cooling part (not shown) of the fuel cell 5A, and the cooling water is supplied between the fuel cell 5A and the water tank. Is circulated to keep the fuel cell 5A at an appropriate temperature.
[0014]
On the end plate 3 side, the unit cell 1B at the end adjacent to the end plate 3 has a fuel chamber facing the end plate 3, and the fuel chamber has passed through the heat medium chamber 6 as described above. Since the high-temperature reformed gas is supplied, temperature drop during power generation is prevented. On the other hand, the unit cell 1A at the end on the end plate 4 side has an air chamber facing the end plate 4 side, and is cooled because normal temperature air taken in from outside air is supplied to the air chamber. The temperature drops inside. Therefore, it is necessary to take measures against the temperature increase as described above for the unit cell 1A.
[0015]
FIG. 2 is a graph obtained by measuring the temperature transition at the start of the fuel cell 5A. When the fuel cell 5A is stopped before starting, the fuel cell 5A is cooled to about room temperature, and the reformed gas is not supplied until it reaches a predetermined temperature by preheating. When the temperature of the fuel cell 5A is raised to nearly 80 ° C., the reformed gas is introduced into the heat medium chamber 6 and power generation is started. According to this measurement result, the unit cell 1A at the end on the end plate 4 side showed almost the same tendency as the temperature transition of the unit cells located in other parts. It has been found that power generation is efficient with almost no temperature distribution in each unit cell. In this case, it is possible to efficiently raise the temperature of the unit cell 1A at the end by allowing the entire amount of the reformed gas to pass through the heat medium chamber 6 and interposing the heat diffusion plate 7.
[0016]
FIG. 3 shows a second embodiment of a polymer electrolyte fuel cell according to the present invention. Reference numeral 1 denotes a unit cell, which is a fuel electrode on one surface of the solid polymer electrolyte membrane and an air electrode on the other surface. , A fuel chamber in which fuel gas circulates on the fuel electrode side of the cell, and an air chamber in which air circulates on the air electrode side. Reference numeral 2 denotes a laminated body, which is formed by stacking a large number of the unit cells 1, metal end plates 3 and 4 are applied to both ends of the laminated body 2, and tightened with bolts (not shown) to be integrated into a fuel cell 5B is formed.
[0017]
In the fuel cell 5B, a heat medium chamber 6 is provided between one end plate 4 and the unit cell 1A at the end on the end plate 4 side, and between the heat medium chamber 6 and the unit cell 1A, A heat diffusion plate 7, which is a partition plate having high thermal conductivity, is interposed, and a cooling water flow passage 7 a is provided inside the heat diffusion plate 7. In the same manner as described above, the entire amount of hydrogen-rich reformed gas passes through the heat medium chamber 6 and is supplied to the fuel chambers of all unit cells after the passage.
[0018]
Also in this case, the temperature of the unit cell 1A at the end on the end plate 4 side can be efficiently increased by allowing the entire amount of the reformed gas to pass through the heat medium chamber 6 and interposing the heat diffusion plate 7. The reason why the cooling water flow passage 7a is provided in the heat diffusion plate 7 is to prevent the heat diffusion plate 7 from being abnormally heated by the high-temperature reformed gas. That is, it is for cooling the thermal diffusion plate 7 by passing cooling water through the cooling water flow passage 7a, thereby adjusting the temperature rise of the unit cell 1A at the end to prevent the temperature from rising excessively. As the cooling water, cooling water discharged from the cooling section of the fuel cell 5B can be used, and the cooling water warmed by heat exchange with the heat diffusion plate 7 is returned to the water tank. The cooling water to be used is not limited to this.
[0019]
FIG. 4 is a graph obtained by measuring the temperature transition at the start of the fuel cell 5B. According to this measurement result, it was found that the entire amount of the reformed gas was allowed to pass through the heat medium chamber 6 and the end unit cell 1A was efficiently heated by the presence of the heat diffusion plate 7. Furthermore, it was found that the temperature of the fuel cell 5B during power generation can be maintained at a predetermined temperature (about 80 ° C.) by circulating the cooling water.
[0020]
FIG. 5 shows a third embodiment of a polymer electrolyte fuel cell according to the present invention. Reference numeral 1 denotes a unit cell, which is a fuel electrode on one surface of the polymer electrolyte membrane and an air electrode on the other surface. , A fuel chamber in which fuel gas circulates on the fuel electrode side of the cell, and an air chamber in which air circulates on the air electrode side. Reference numeral 2 denotes a laminated body, which is formed by stacking a large number of the unit cells 1, metal end plates 3 and 4 are applied to both ends of the laminated body 2, and tightened with bolts (not shown) to be integrated into a fuel cell 5C is formed.
[0021]
In this fuel cell 5C, a heat medium chamber 6 is provided between one end plate 4 and a unit cell 1A at the end on the end plate 4 side, and between this heat medium chamber 6 and the unit cell 1A, A heat diffusion plate 7 which is a partition plate having high thermal conductivity is interposed, and a cooling water flow passage 8 is provided between the heat medium chamber 6 and the end plate 4. Also in this case, the entire amount of hydrogen-rich reformed gas passes through the heat medium chamber 6 and is supplied to the fuel chambers of all the unit cells after the passage.
[0022]
In this case, since the entire amount of the reformed gas is passed through the heat medium chamber 6 and the heat diffusion plate 7 is interposed between the heat medium chamber 6 and the end unit cell 1A, the end unit cell 1A. Can be efficiently performed. The cooling water flow passage 8 is provided between the heat medium chamber 6 and the end plate 4 because the temperature of the end unit cell 1A is reduced by cooling the high-temperature reformed gas passing through the heat medium chamber 6 with the cooling water. This is to prevent the fuel cell temperature from rising excessively and to prevent an abnormal increase in the fuel cell temperature. Further, the cooling water can heat the end plate 4 with the heat taken from the reformed gas, thereby preventing the cooling water from being overcooled.
[0023]
FIG. 6 is a graph obtained by measuring the temperature transition of the main part at the time of startup in the fuel cell 5C. According to this measurement result, the entire amount of the reformed gas is passed through the heat medium chamber 6 and the end unit cell 1A is efficiently heated by the heat diffusion plate 7 being interposed, and the end unit is cooled by cooling water. It has been found that the temperature of the cell 1A is prevented from rising excessively, and that the temperature of the fuel cell 5C can be prevented from rising abnormally and kept at an appropriate temperature. In addition, it was recognized that the temperature of the cooling water passing through the cooling water flow passage 8 was increased by heat exchange with the reformed gas after the start of power generation.
[0024]
FIG. 7 shows a fourth embodiment of the polymer electrolyte fuel cell according to the present invention. Reference numeral 1 denotes a unit cell, which is a fuel electrode on one surface of the polymer electrolyte membrane and an air electrode on the other surface. , A fuel chamber in which fuel gas circulates on the fuel electrode side of the cell, and an air chamber in which air circulates on the air electrode side. Reference numeral 2 denotes a laminated body, which is formed by stacking a large number of the unit cells 1, metal end plates 3 and 4 are applied to both ends of the laminated body 2, and tightened with bolts (not shown) to be integrated into a fuel cell 5D is formed.
[0025]
In the fuel cell 5D, a heat medium chamber 6 is provided between one end plate 4 and the unit cell 1A at the end on the end plate 4 side, and between the heat medium chamber 6 and the unit cell 1A, A heat diffusion plate 7 which is a partition plate having high thermal conductivity is interposed, a cooling water flow passage 8 is provided next to the heat medium chamber 6 (on the side opposite to the heat diffusion plate 7), and the cooling water flow passage 8 and the end plate 4 are further provided. The unreacted hydrogen gas flow passage 9 is provided between the two. A total amount of hydrogen-rich reformed gas passes through the heat medium chamber 6 and is supplied to the fuel chambers of all the unit cells after the passage. The unreacted hydrogen gas flow passages 9 are not discharged from the fuel cell 5D. Reactive hydrogen gas passes through.
[0026]
In this case, since the entire amount of the reformed gas is passed through the heat medium chamber 6 and the heat diffusion plate 7 is interposed between the heat medium chamber 6 and the end unit cell 1A, the end unit cell 1A The temperature can be increased efficiently. Further, by providing the cooling water flow passage 8, it is possible to prevent the temperature of the unit cell 1A at the end from excessively rising and to prevent an abnormal increase in the temperature of the fuel cell and to maintain the temperature appropriately. The unreacted hydrogen gas flow passage 9 is provided in order to adjust the coolant temperature passing through the cooling water flow passage 8 by passing the unreacted hydrogen gas discharged from the fuel cell 5D through the unreacted hydrogen gas flow passage 9. is there. As a result, the reformed gas can be prevented from being overcooled, and the end plate 4 can be warmed to prevent the reformed gas from being overcooled.
[0027]
FIG. 8 is a graph obtained by measuring the temperature transition at the start of the fuel cell 5D. According to this measurement result, the entire amount of the reformed gas is allowed to pass through the heat medium chamber 6 and the end diffusion unit 7 is interposed to efficiently raise the temperature of the end unit cell 1A. It has been found that the unit cell 1A can be kept at an appropriate temperature while preventing the temperature of the unit cell 1A from rising excessively and preventing an abnormal temperature rise of the fuel cell 5D. Although the air supplied to the fuel cell 5D was at room temperature, it was recognized that the unreacted hydrogen gas was discharged at about 78 ° C.
[0028]
FIG. 9 shows a fifth embodiment of a polymer electrolyte fuel cell according to the present invention. Reference numeral 1 denotes a unit cell, which is a fuel electrode on one surface of the solid polymer electrolyte membrane and an air electrode on the other surface. , A fuel chamber in which fuel gas circulates on the fuel electrode side of the cell, and an air chamber in which air circulates on the air electrode side. Reference numeral 2 denotes a laminated body, which is formed by stacking a large number of the unit cells 1, metal end plates 3 and 4 are applied to both ends of the laminated body 2, and tightened with bolts (not shown) to be integrated into a fuel cell 5E is formed.
[0029]
In the fuel cell 5E, a heat medium chamber 6 is provided between one end plate 4 and the unit cell 1A at the end on the end plate 4 side, and between the heat medium chamber 6 and the unit cell 1A, A heat diffusion plate 7 which is a partition plate having high thermal conductivity is interposed, a cooling water flow passage 8 is provided next to the heat medium chamber 6 (on the opposite side to the heat diffusion plate 7), and a water permeable member 10 such as The structure is such that it is partitioned by a water permeable membrane or a porous plate, and an unreacted hydrogen gas flow passage 9 is provided between the cooling water flow passage 8 and the end plate 4. A total amount of hydrogen-rich reformed gas passes through the heat medium chamber 6 and is supplied to the fuel chambers of all the unit cells after passing through. The unreacted hydrogen gas flow passage 9 is unreacted discharged from the fuel cell 5E. Hydrogen gas passes through.
[0030]
In this case, since the entire amount of the reformed gas is passed through the heat medium chamber 6 and the heat diffusion plate 7 is interposed between the heat medium chamber 6 and the end unit cell 1A, the end unit cell 1A The temperature can be increased efficiently, and the cooling water flow passage 8 is provided to prevent the temperature of the unit cell 1A at the end from excessively rising and to keep the fuel cell temperature from rising abnormally and to keep it at an appropriate temperature. Can do. By providing the unreacted hydrogen gas flow passage 9, it is possible to prevent the temperature adjustment of the cooling water passing through the cooling water flow passage 8 and the end plate 4 from being overcooled. Further, by interposing the water-permeable member 10 between the heat medium chamber 6 and the cooling water flow passage 8, a part of the cooling water passing through the cooling water flow passage 8 is introduced into the heat medium chamber 6 to humidify the reformed gas. be able to. Thereby, the gas-liquid mixer which was conventionally used for humidification of reformed gas becomes unnecessary. By humidifying the reformed gas, the electrolyte membrane in each unit cell is maintained in a wet state, and normal power generation is performed. In some cases, the air supplied to the fuel cell is humidified, and the electrolyte membrane is wetted by humidification of the air.
[0031]
FIG. 10 is a graph obtained by measuring the temperature transition at startup and the humidity of the reformed gas in the fuel cell 5E. According to this measurement result, the entire amount of the reformed gas is passed through the heat medium chamber 6 and the end unit cell 1A is efficiently heated by the heat diffusion plate 7 being interposed, and the end unit is cooled by cooling water. While preventing the temperature of the cell 1A from rising excessively, it is possible to keep the fuel cell temperature from rising abnormally and to keep it at an appropriate temperature. In addition, the air supplied to the fuel cell 5E is at room temperature, but rapidly rises after the start of power generation and eventually reaches a substantially constant temperature of about 78 ° C. The reformed gas humidity was unstable and unstable in the range of 60 to 65% Rh in the initial stage, but eventually increased and stabilized at about 85% Rh.
[0032]
【The invention's effect】
(1) According to the polymer electrolyte fuel cell of claim 1 of the present invention, the entire amount of the reformed gas is passed through the heat medium chamber, and the thermal conductivity is provided between the heat medium chamber and the end unit cell. By providing a high partition plate (heat diffusion plate), the temperature of the unit cell at the end can be efficiently increased.
Further, the power generation efficiency can be increased by supplying the reformed gas that has passed through the heat medium chamber to each unit cell.
(2) According to the polymer electrolyte fuel cell of claim 2 of the present invention, it is possible to prevent the heat diffusion plate from becoming abnormally hot by passing cooling water through the inside of the heat diffusion plate. It is possible to prevent the temperature from rising excessively.
(3) According to the polymer electrolyte fuel cell of claim 3 of the present invention, the reformed gas is cooled by the cooling water to prevent the temperature of the unit cell at the end from being excessively raised and the temperature of the fuel cell is abnormally increased. Can be kept at an appropriate temperature.
(4) According to the polymer electrolyte fuel cell of claim 4 of the present invention, the cooling water discharged from the fuel cell can be used as the cooling water.
(5) According to the polymer electrolyte fuel cell of claim 5 of the present invention, the temperature of the cooling water is adjusted by passing the unreacted hydrogen gas discharged from the fuel cell to prevent the reformed gas from being overcooled. At the same time, the end plate can be warmed to prevent overcooling.
(6) According to the polymer electrolyte fuel cell of claim 6 of the present invention, the reformed gas passing through the heat medium chamber is humidified by interposing a water-permeable member between the heat medium chamber and the cooling water flow passage. be able to. By humidifying the reformed gas, the electrolyte membrane in the unit cell can be kept in a wet state.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a first embodiment of a polymer electrolyte fuel cell according to the present invention. FIG. 2 is a graph showing a fuel cell temperature transition at start-up in the first embodiment. Explanatory drawing which shows 2nd Embodiment of the polymer electrolyte fuel cell which concerns on FIG. 4 A graph which shows fuel cell temperature transition at the time of starting in 1st Embodiment FIG. 5 Explanatory drawing which shows 3rd Embodiment of a fuel cell. FIG. 6 is a graph which shows fuel cell temperature transition at the time of starting in 3rd Embodiment. FIG. 7 is 4th Embodiment of the polymer electrolyte fuel cell which concerns on this invention. FIG. 8 is a graph showing the transition of the fuel cell temperature at start-up in the fourth embodiment. FIG. 9 is an explanatory diagram showing the fifth embodiment of the polymer electrolyte fuel cell according to the present invention. FIG. 10 is a graph showing fuel cell temperature transition and reformed gas humidity at start-up in the fifth embodiment. Akira]
DESCRIPTION OF SYMBOLS 1 ... Unit cell 1A ... End unit cell 2 ... Laminated body 3, 4 ... End plate 5A-5E ... Fuel cell 6 ... Heat-medium chamber 7 ... Heat diffusion plate 7a ... Cooling water flow path 8 ... Cooling water flow path 9 ... Not yet Reactive hydrogen gas flow passage 10 ... Permeable member

Claims (6)

A fuel electrode is connected to one side of the solid polymer electrolyte membrane, an air electrode is joined to the other side, and a fuel chamber in which fuel gas flows is arranged on the fuel electrode side of the cell, and an air chamber in which air is circulated on the air electrode side. to the unit cell and without, against first end plate on the side of the fuel chamber of the stack of superposed multiple the unit cell is an end face, said air chamber and the second end plate on the side to be the end face, respectively in the solid high polymer fuel cell was clamped integrated
A heat medium chamber provided between the second end plate and the unit cell at the end on the second end plate side ;
And a thermal diffusion plate provided between said heating medium chamber and a unit cell of said end portion,
With flowing whole amount the fuel gas to the heating medium chamber, a solid polymer fuel cell and supplying the fuel gas after the heating medium chamber passes through the fuel chamber of each unit cell. 2. The polymer electrolyte fuel cell according to claim 1, wherein a cooling water flow passage is provided in the heat diffusion plate. 2. The polymer electrolyte fuel cell according to claim 1, wherein a cooling water flow passage is provided between the heat medium chamber and the end plate. 4. The polymer electrolyte fuel cell according to claim 2, wherein cooling water discharged from the fuel cell flows through the cooling water flow passage. 5. The solid polymer fuel cell according to claim 2, 3 or 4, wherein an unreacted hydrogen gas flow passage discharged from the fuel cell is provided between the cooling water flow passage and the end plate. Fuel cell. 6. The polymer electrolyte fuel cell according to claim 2, wherein the heat medium chamber and the cooling water flow passage are partitioned by a water permeable member.

Images