JP6356480B2 - Hot module - Google Patents

Description

  The present invention relates to a hot module that houses a fuel cell stack that generates power with fuel gas and oxidant gas.

  There are some which are indicated by patent documents 1-4 as a hot module which stored a fuel cell stack.

Japanese Patent Laid-Open No. 9-7624 JP 2007-73357 A JP 2010-225454 A Special table 2010-504607

  The hot module contains a fuel cell stack in which power generation cells that generate power with fuel gas and oxidant gas are stacked. In the power generation cell, the fuel gas and the oxidant gas react to generate heat together with electricity when generating power. The temperature of the fuel cell stack may vary depending on the part. For example, the central part in the vertical direction of the fuel cell stack is likely to have a higher temperature than the upper part and the lower part of the fuel cell stack.

  When the temperature of the power generation cell becomes higher than necessary, the cell deteriorates or the durability of the power generation cell decreases. For this reason, it is necessary to cool the central portion of the fuel cell stack so that it does not become unnecessarily high. However, the hot module disclosed in the prior art preferentially cools the central portion of the fuel cell stack. In some cases, the temperature of the lower or upper portion where the temperature of the fuel cell stack tends to decrease may be lowered, and there is room for improvement.

  In view of the above facts, an object of the present invention is to provide a hot module that can preferentially cool the portion of the fuel cell stack that is at the highest temperature.

The hot module according to claim 1 is a fuel cell stack in which power generation cells that generate power with fuel gas and oxidant gas are stacked, and a raw material by a reforming reaction using power generation reaction heat generated in the fuel cell stack. A reformer that obtains the fuel gas from gas and supplies the fuel gas to the power generation cell, and is disposed around the fuel cell stack so as to face the entire horizontal side portion of the fuel cell stack, and the fuel cell An inflow portion for injecting a refrigerant at a position facing the highest temperature portion of the cell stack, and a passage through which the refrigerant flows from the inflow portion to a position facing a low temperature portion of the fuel cell stack An endothermic device, and the fuel cell stack, the reformer, and a storage container for storing the endothermic device.

  In the hot module according to the first aspect, the power generation cell generates power with the fuel gas and the oxidant gas, and the power generation cell generates heat.

  When the refrigerant is caused to flow into the passage from the inflow portion of the heat absorbing device, the refrigerant first flows into a position opposite to the portion having the highest temperature of the fuel cell stack, and then the portion having the lower temperature of the fuel cell stack. Since it flows in the position which opposes, the radiation heat radiated | emitted from the fuel cell stack can be absorbed most efficiently in the position which opposes the part which becomes the highest temperature of a fuel cell stack.

  In the heat absorption device, the refrigerant flowing through the passage at the position facing the low temperature portion of the fuel cell stack has a higher temperature than the refrigerant flowing in the vicinity of the inflow portion, and thus the cooling efficiency is reduced. However, the fuel cell stack There is no shortage of cooling capacity in the low temperature part.

  According to a second aspect of the present invention, in the hot module according to the first aspect, the inflow portion is provided at a position facing a central portion in the vertical direction that is the highest temperature of the fuel cell stack, The passage allows the refrigerant to flow from the inflow portion to a position corresponding to the upper portion of the fuel cell stack, and from the inflow portion to a position facing the lower portion of the fuel cell stack.

  In a fuel cell stack in which power generation cells are stacked, heat tends to be trapped in the central part in the vertical direction, and the central part in the vertical direction tends to be hotter than the upper part and the lower part.

  In the hot module according to claim 2, when the refrigerant is caused to flow into the passage from the inflow portion of the heat absorbing device, the refrigerant first flows into a position facing the central portion in the vertical direction of the fuel cell stack, and then Since it flows to a position facing the upper part of the fuel cell stack and a position facing the lower part of the fuel cell stack, it is emitted from the fuel cell stack at a position facing the center in the vertical direction of the fuel cell stack. The radiant heat can be absorbed most efficiently.

  In the heat absorption device, the refrigerant flowing through the passages at the positions facing the upper and lower portions of the fuel cell stack has a higher temperature than the refrigerant flowing in the vicinity of the inflow portion, and thus the cooling efficiency is reduced. However, the fuel cell stack Since the temperature of the upper part and the lower part of the fuel cell is lower than the temperature of the central part, the cooling capacity of the upper part and the lower part of the fuel cell stack is not insufficient.

  According to a third aspect of the present invention, in the hot module according to the second aspect, the passage includes a central passage that includes the inflow portion and makes a round around a position facing the central portion in the vertical direction of the fuel cell stack; An upper passage that is connected to the downstream end of the central passage and is disposed on the upper side of the central passage and circulates at a position facing the upper portion of the fuel cell stack, and is connected to the downstream end of the central passage and A lower passage that is disposed below the central passage and circulates in a position facing the lower portion of the fuel cell stack.

  In the hot module according to claim 3, the radiant heat radiated from the central portion in the vertical direction of the fuel cell stack is effective with the refrigerant in the central passage that makes one round at a position facing the vertical central portion of the fuel cell stack. Can be absorbed. The radiant heat radiated from the upper part of the fuel cell stack can be absorbed by the refrigerant in the upper passage, and the radiant heat radiated from the lower part of the fuel cell stack can be absorbed by the refrigerant flowing in the lower passage. .

  According to a fourth aspect of the present invention, in the hot module according to the third aspect, the upper side passage and the lower side passage are spirally wound around the fuel cell stack.

  Since the upper passage and the lower passage are spirally wound around the fuel cell stack, the radiant heat radiated from the fuel cell stack that is long in the vertical direction can be effectively absorbed.

  According to a fifth aspect of the present invention, in the hot module according to any one of the first to fourth aspects, the heat absorption device includes an inner wall surrounding the fuel cell stack and an outer side of the inner wall. The passage is provided between the outer wall which is arranged and surrounds the inner wall.

  In the hot module according to the fifth aspect, since the radiant heat radiated from the fuel cell stack is received by the surface of the inner wall of the heat absorbing device, the heat receiving area can be increased.

  A sixth aspect of the present invention is the hot module according to any one of the first to fifth aspects, wherein the heat absorption device absorbs radiant heat on a surface facing the fuel cell stack. Is provided.

  In the hot module according to claim 6, since the heat absorption layer is provided on the surface of the heat absorption device facing the fuel cell stack, the fuel cell stack is separated from the case where the heat absorption layer is not provided. Can be efficiently absorbed.

  According to a seventh aspect of the present invention, in the hot module according to the sixth aspect, the heat absorbing device is formed of a metal facing a portion of the fuel cell stack, and the heat absorption layer is formed on a surface of the metal. Oxide film.

  Since the heat absorption layer is an oxide film, the heat absorption layer can be easily formed on the metal surface simply by heating the metal.

  The invention according to claim 8 is the hot module according to any one of claims 1 to 7, wherein the refrigerant is an oxidant gas before being supplied to the power generation cell.

  In the hot module according to the eighth aspect, the oxidant gas before being supplied to the power generation cell can be preheated by the heat absorption device.

As described above, the hot module according to claim 1 has an excellent effect of preferentially cooling the portion of the fuel cell stack that has the highest temperature.
According to the hot module of the second aspect, the central portion of the fuel cell stack can be preferentially cooled.
According to the hot module of claim 3, by using the upper passage and the lower passage, the heat of the upper part and the heat of the lower part of the fuel cell stack can be efficiently absorbed under the same conditions. it can.
According to the hot module of the fourth aspect, heat can be absorbed without interruption along the outer periphery of the fuel cell stack.
According to the hot module of the fifth aspect, heat can be efficiently absorbed by the inner wall.
According to the hot module of the sixth aspect, heat can be efficiently absorbed.
According to the hot module of the seventh aspect, since the heat absorption layer is a metal oxide film, the heat absorption layer is strong against heat and excellent in durability.
According to the hot module of the eighth aspect, since no separate device for preheating the oxidant gas is required, an increase in the number of parts can be suppressed.

It is a side view which shows schematic structure of a hot module. It is a piping diagram which shows the principal part of the fuel cell system comprised including the hot module. It is a perspective view which shows a 3rd heat exchanger.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
(Overall configuration of hot module)
As shown in FIG. 1, the hot module 10 of the fuel cell system 8 includes a box-shaped heat insulation container 12. Inside the heat insulation container 12, a fuel cell stack 14, a vaporizer 15, and a reformer 16 are provided. The first heat exchanger 18A, the second heat exchanger 18B, the third heat exchanger 18C, and the like are accommodated.

  The fuel cell stack 14 is formed, for example, by forming a plurality of flat power generation cells in a vertical direction in a cubic shape. The power generation cell includes an anode, a cathode, an electrolyte, and the like, and has a known structure as a solid oxide fuel cell that generates electricity from a fuel gas and an oxidant gas by an electrochemical reaction. The fuel cell stack 14 is not limited to the structure of the present embodiment, and other known structures such as a polymer electrolyte fuel cell, a phosphoric acid fuel cell, an alkaline electrolyte fuel cell, a molten carbonate fuel cell, etc. Or other shapes

  The vaporizer 15 vaporizes the water supplied from the outside with the heat of exhaust gas described later to generate water vapor. The reformer 16 mixes a raw material gas (for example, city gas) supplied from the outside and water vapor generated by the vaporizer 15 to give heat of exhaust gas described later, and converts the raw material gas into a steam reforming method. To produce a fuel gas containing hydrogen.

  As shown in FIG. 2, the first heat exchanger 18 </ b> A and the second heat exchanger 18 </ b> B heat the air supplied from the outside with the heat H <b> 1 of the exhaust gas passing through the exhaust pipe 58 described later. The third heat exchanger 18 </ b> C absorbs the radiant heat H <b> 2 from the fuel cell stack 14 and heats the air supplied to the fuel cell stack 14.

  A blower 20 that blows air is provided outside the hot module 10. An air outlet of the blower 20 is connected to a branch 24 via an air pipe 22, and the branch 24 includes a first valve 26. Connected to the air inlet of the first heat exchanger 18A via the air pipe 28, connected to the air inlet of the second heat exchanger 18B via the air pipe 32 provided with the second valve 30, and the third It is connected to the air inlet of the third heat exchanger 18C through an air pipe 36 provided with a valve 34.

  The air blown from the blower 20 opens and closes the first heat exchanger 18A, the second heat exchanger 18B, and the third heat exchanger 18C by opening and closing the first valve 26, the second valve 30, and the third valve 34. When the fuel cell stack 14 is supplied in a preheated state after passing through, it is supplied to the fuel cell stack 14 in a state of being preheated through the second heat exchanger 18B and the third heat exchanger 18C. Or supplied to the fuel cell stack 14 in a preheated state through only the third heat exchanger 18C.

  The air outlet of the first heat exchanger 18A and the air inlet of the second heat exchanger 18B are connected via an air pipe 38, and the air outlet of the second heat exchanger 18B and the third heat exchanger 18C The air inlet is connected via an air pipe 40. The air outlet of the third heat exchanger 18C and the air inlet of the fuel cell stack 14 are connected via an air pipe 42.

  The hot module 10 includes a gas pipe 44 that supplies a raw material gas supplied from the outside of the heat insulating container 12 to the reformer 16, and a water pipe 46 that supplies water supplied from the outside of the heat insulating container 12 to the vaporizer 15. I have. The water pipe 46 is connected to the inlet of the vaporizer 15. One end of a water pipe 48 is connected to the discharge port of the vaporizer 15.

  The gas pipe 44 and the water pipe 48 are connected to the branch 50, and the branch 50 is connected to the inlet of the reformer 16 through the pipe 52. In the reformer 16, the water vapor generated in the vaporizer 15 and the raw material gas supplied from the outside are supplied and heated, so that a fuel gas (reformed gas) containing hydrogen is generated.

  The gas outlet of the reformer 16 and the gas inlet of the fuel cell stack 14 are connected via a gas pipe 54. As shown in FIG. 1, a combustion unit 56 to which off gas and air discharged from the fuel cell stack 14 are supplied is provided on the upper portion of the fuel cell stack 14. In the combustion unit 56 of the present embodiment, diffusion combustion is performed.

  As shown in FIG. 2, the exhaust gas generated in the combustion unit 56 is discharged to the outside of the heat insulating container 12 through the exhaust pipe 58, but until the exhaust pipe 58 is discharged from the heat insulating container 12 to the outside. Then, the reformer 16, the vaporizer 15, the second heat exchanger 18B, and the first heat exchanger 18A are contacted in this order to convert the heat H1 of the exhaust gas into the reformer 16, the vaporizer 15, and the second heat exchanger. 18B and the first heat exchanger 18A can be sequentially applied.

(Third heat exchanger)
As shown in FIGS. 1 and 3, a third heat exchanger 18 </ b> C formed so as to surround the periphery of the fuel cell stack 14 in the horizontal direction is disposed inside the heat insulating container 12. The third heat exchanger 18C includes an inner wall 120 formed into a rectangular shape in plan view with four stainless steel plates, and an outer wall 122 formed with four stainless steel plates arranged at intervals outside the inner wall 120. It has. A rectangular frame-shaped opening formed between the upper end of the inner wall 120 and the upper end of the outer wall 122 is closed with an upper lid 124 formed in a rectangular frame shape with a stainless steel plate. A square frame-shaped opening formed between the lower end of the inner wall 120 and the lower end of the outer wall 122 is closed with a lower lid 126 formed in a square frame shape with a stainless steel plate. As a result, in the third heat exchanger 18C, an internal space 128 that is sealed between the inner wall 120, the outer wall 122, the upper lid 124, and the lower lid 126 is formed.

  The inner wall 120 is provided with a heat absorption layer (not shown) on the surface facing the side surface of the fuel cell stack 14 in order to efficiently absorb the radiant heat radiated from the fuel cell stack 14. The heat absorption layer of this embodiment is a blue-black oxide film obtained by oxidizing the surface of stainless steel.

Between the outer wall 122 and the inner wall 120, passage partition walls 130, 132, 134, 136 formed of a stainless steel plate and formed in a square frame shape are arranged in order with an interval upward.
The inner peripheral portions of the passage partition walls 130, 132, 134, 136 are tightly fixed to the inner wall 120, and the outer peripheral portions of the passage partition walls 130, 132, 134, 136 are firmly fixed to the outer wall 122. For this reason, the internal space 128 is divided into five in the vertical direction by these passage partition walls 130, 132, 134, 136, and the first passage 138, the passage partition wall 130 and the passage between the lower lid 126 and the passage partition wall 130. The second passage 140 is between the partition walls 132, the third passage 142 is between the passage partition 132 and the passage partition 134, the fourth passage 144 is between the passage partition 134 and the passage partition 136, the passage partition 136 and the upper lid 124, and the like. A fifth passage 146 is defined between the two.

  The first passage 138, the second passage 140, the third passage 142, the fourth passage 144, and the fifth passage 146 make a round around the inner wall 120, and have one end in the longitudinal direction of the first passage 138. A partition wall 148 is provided between the other end portion, a partition wall 150 is provided between one end portion of the second passage 140 in the longitudinal direction and the other end portion, and one end portion of the third passage 142 in the longitudinal direction. A partition wall 152 is provided between the first end and the other end, and a partition wall 154 is provided between one end and the other end of the fourth passage 144 in the longitudinal direction, and the fifth passage 146 in the longitudinal direction. A partition wall 156 is provided between one end portion and the other end portion of each of the passages, and one end portion and the other end portion in the longitudinal direction of each passage are adjacent to each other through the partition wall.

  The third passage 142 facing the intermediate portion in the vertical direction of the third heat exchanger 18C includes an air inlet 158 formed in the outer wall 122 at one end in the longitudinal direction. An air pipe 42 is connected to the air inlet 158. The third passage 142 is disposed at a position facing the intermediate portion in the vertical direction of the fuel cell stack 14.

  The other end portion in the longitudinal direction of the third heat exchanger 18C is connected to one end portion in the longitudinal direction of the second passage 140 through an opening 160 formed in the passage partition wall 132, and the opening 162 formed in the passage partition wall 134. And is connected to one end of the fourth passage 144 in the longitudinal direction.

  The other end in the longitudinal direction of the second passage 140 is connected to one end of the first passage 138 through an opening 164 formed in the passage partition wall 130. The other end in the longitudinal direction of the first passage 138 includes a lower air discharge port 166 formed in the outer wall 122.

  The other end in the longitudinal direction of the fourth passage 144 is connected to one end of the fifth passage 146 through an opening 168 formed in the passage partition 136. The other end in the longitudinal direction of the fifth passage 146 is provided with an upper air outlet 170 formed in the outer wall 122. The lower air discharge port 166 and the upper air discharge port 170 are connected to the combustion unit 56 via a pipe 172 as shown in FIG.

  In the third heat exchanger 18C configured as described above, when air is introduced from the air inlet 158, the air passes through the third passage 142 and makes one round of the fuel cell stack 14, and then the fuel cell. While passing through the second passage 140 and the first passage 138 so as to make two rounds at a position facing the lower portion (lower side portion) of the cell stack 14, it is discharged from the lower air discharge port 166, and the fuel cell stack 14 It passes through the fourth passage 144 and the fifth passage 146 so as to make two rounds at a position facing the upper portion (upper portion) and is discharged from the upper air discharge port 170.

  In the third heat exchanger 18C, a passage is formed spirally upward and downward from the third passage 142, and the air flowing in from the air inlet 158 moves upward in the third heat exchanger 18C. Flows in a spiral toward the bottom and flows in a spiral toward the bottom.

(Function)
Next, the operation of this embodiment will be described.
Air (oxidant gas) blown from the blower 20 passes through the first heat exchanger 18A, the second heat exchanger 18B, and the third heat exchanger 18C, is preheated, and is supplied to the fuel cell stack 14. The
On the other hand, water supplied from the outside is converted into water vapor by the vaporizer 15, and the reformer 16 is mixed with the gas supplied from the outside and the water vapor generated by the vaporizer 15 to give heat of the exhaust gas. The fuel gas is reformed and supplied to the fuel cell stack 14.

  When fuel gas and air are supplied to each power generation cell of the fuel cell stack 14, the power generation cell generates power and generates heat. Since the fuel cell stack 14 is formed in a cubic shape by stacking a plurality of power generation cells, the heat at the central portion of the fuel cell stack 14 is hardly released to the outside, and the heat is trapped at the central portion, so that the vertical direction The central part is likely to be hotter than both ends in the vertical direction.

  In the third heat exchanger 18C, air is introduced from the air inlet 158, and air is introduced from the third passage 142 facing the intermediate portion in the vertical direction of the fuel cell stack 14, and then the second passage 140, the first The fuel cell stack 14 is supplied to the fuel cell stack 14 via the passage 138 and is supplied to the fuel cell stack 14 via the fourth passage 144 and the fifth passage 146. As a result, the vertical middle portion of the fuel cell stack 14 can be preferentially cooled.

  Further, the third heat exchanger 18C of the present embodiment is provided with a heat absorption layer that absorbs radiant heat from the fuel cell stack 14 on the surface of the inner wall 120 facing the fuel cell stack 14, so that the heat Compared with the case where the absorption layer is not provided, radiant heat can be absorbed efficiently, and the fuel cell stack 14 can be absorbed efficiently. Since the heat absorption layer of the present embodiment is made of a stainless steel oxide film, it can be easily formed, is resistant to heat, and has excellent durability.

  As described above, in the hot module 10 of the present embodiment, the middle part of the fuel cell stack 14 that has the highest temperature in the vertical direction can be preferentially cooled. It is possible to suppress deterioration of the power generation cell in the middle portion in the vertical direction due to high temperature, and the durability of the power generation cell can be improved.

  In the third heat exchanger 18C, the refrigerant that flows through the passages (the first passage 138, the second passage 140, the fourth passage 144, and the fifth passage 146) facing the upper and lower portions of the fuel cell stack 14. However, since the temperature is higher than that of the refrigerant flowing through the third passage 142, the cooling efficiency is lowered. The cooling capacity of the upper part and the lower part of the stack 14 is not insufficient.

  By preferentially cooling the vertical middle portion that is high in the fuel cell stack 14, the temperature difference between the vertical center of the fuel cell stack 14 and both ends in the vertical direction can be reduced. Efficient power generation can be performed by equalizing the power generation capacity of each power generation cell.

(Other embodiments)
In the third heat exchanger 18C of the above-described embodiment, the five passages around the fuel cell stack 14 are formed in the vertical direction. However, the present invention is not limited to this, and the number of passages is four or less. It may be 5 stages or more. Further, the third heat exchanger 18C may be formed with a single spiral passage whose entire longitudinal direction is inclined with respect to the horizontal direction. In this case, air may be introduced from the central portion in the vertical direction of the passage, and air may be discharged from the upper end and the lower end of the spiral passage. As a single spiral passage, for example, a round pipe, a square pipe or the like bent into a spiral shape can be cited.

  In the above embodiment, air supplied to the fuel cell stack 14 is used to cool the fuel cell stack 14, but the present invention is not limited to this, and refrigerant other than the air supplied to the fuel cell stack 14 is used. It may be used.

  For example, the vaporizer 15 that heats water is formed in the same structure as the third heat exchanger 18C, and is disposed around the fuel cell stack 14, and the radiant heat of the fuel cell stack 14 is absorbed by water and the fuel cell. The cell stack 14 may be cooled.

  Further, the reformer 16 is formed in the same structure as the third heat exchanger 18C and disposed around the fuel cell stack 14, and the radiant heat of the fuel cell stack 14 is absorbed by the mixed gas of water vapor and gas. The fuel cell stack 14 may be cooled.

  In addition, the air outlet of the second heat exchanger 18B and the air inlet of the fuel cell stack 14 are connected via an air pipe 40, and tap water is supplied to the third heat exchanger 18C, thereby the fuel cell. Tap water heated by the radiant heat of the cell stack 14 may be used for hot water supply.

  In the above embodiment, an oxide film is used as the heat absorption layer. However, the present invention is not limited to this, and the heat absorption layer is not limited to the oxide film, and constitutes the inner wall 120 as long as it increases the absorption rate of radiant heat. A known material such as a metal (such as copper) that easily absorbs radiant heat and a coating other than an oxide film can be used. The heat absorption layer is preferably close to a black body.

  In the fuel cell system 8 of the present embodiment, the first valve 26, the second valve 30, and the third valve 34 are adjusted to adjust the heat exchange amount of air supplied to the third heat exchanger 18C. The temperature of the battery cell stack 14 can also be controlled.

In the above embodiment, the case where the middle part in the vertical direction becomes the highest temperature in the fuel cell stack 14 is taken as an example. However, depending on the configuration of the fuel cell stack 14 and the arrangement of peripheral devices, the highest temperature is obtained. It is also conceivable that the portion is not the intermediate portion in the vertical direction of the fuel cell stack 14 (for example, the upper side or the lower side is higher than the intermediate portion in the vertical direction). In that case, the air inflow port 158 may be disposed at a position facing the highest temperature portion in the fuel cell stack 14 and the highest temperature portion may be preferentially cooled.
In addition, when there are a plurality of high temperature portions, a plurality of air inlets 158 may be provided for each high temperature portion.

  Although an example of the present invention has been described above, the present invention is not limited to the above, and it is needless to say that various modifications can be made without departing from the spirit of the present invention. .

DESCRIPTION OF SYMBOLS 10 Hot module 12 Thermal insulation container 14 Fuel cell stack 16 Reformer 18C 3rd heat exchanger (heat absorption apparatus)
120 inner wall 122 outer wall 138 first passage (lower passage)
140 Second passage (lower passage)
142 3rd passage (central passage)
144 4th passage (upper passage)
146 5th passage (upper passage)
158 Air inlet (inlet)

Claims (8)

A fuel cell stack in which power generation cells that generate power with fuel gas and oxidant gas are stacked;
A reformer that obtains the fuel gas from a raw material gas by a reforming reaction using power generation reaction heat generated in the fuel cell stack and supplies the fuel gas to the power generation cell;
An inflow portion that is arranged around the fuel cell stack so as to face the entire horizontal side portion of the fuel cell stack and into which a refrigerant flows into a position facing the highest temperature portion of the fuel cell stack An endothermic device comprising a passage through which the refrigerant flows from the inflow portion toward a position facing a low temperature portion of the fuel cell stack,
The fuel cell stack, the reformer, and the hot module having a container, a housing the endothermic device. The inflow portion is provided at a position facing the central portion in the vertical direction that is the highest temperature of the fuel cell stack,
2. The passage according to claim 1, wherein the refrigerant flows from the inflow portion to a position corresponding to an upper portion of the fuel cell stack, and from the inflow portion to a position facing a lower portion of the fuel cell stack. Hot module.   The passage is disposed on the upper side of the central passage connected to the central passage that includes the inflow portion and goes around the position facing the vertical central portion of the fuel cell stack, and the downstream end of the central passage. An upper passage that circulates in a position facing the upper portion of the fuel cell stack, and a lower end of the central passage that is connected to the downstream end of the central passage and faces the lower portion of the fuel cell stack. The hot module according to claim 2, further comprising: a lower passage that goes around the position.   4. The hot module according to claim 3, wherein the upper passage and the lower passage make a plurality of spiral turns around the fuel cell stack. 5.   5. The heat sink according to claim 1, wherein the heat absorption device is provided with the passage between an inner wall that surrounds the periphery of the fuel cell stack and an outer wall that is disposed outside the inner wall and surrounds the inner wall. The hot module according to any one of claims.   The hot module according to any one of claims 1 to 5, wherein the heat absorbing device is provided with a heat absorption layer that absorbs radiant heat on a surface facing the fuel cell stack.   7. The hot module according to claim 6, wherein a portion of the heat absorption device facing the fuel cell stack is formed of metal, and the heat absorption layer is an oxide film formed on a surface of the metal.   The hot module according to any one of claims 1 to 7, wherein the refrigerant is an oxidant gas before being supplied to the power generation cell.

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