COGENERATION SYSTEM

A cogeneration system includes a fuel battery, a heat supply channel, and a first heat exchange portion. The fuel battery houses a fuel battery cell. The heat supply channel causes a medium that recovers heat generated by the fuel battery to flow therein. The first heat exchange portion that is positioned close to the outer side of the fuel battery or positioned within the fuel battery to cause the medium flowing in the heat supply channel to recover the heat generated by the fuel battery.

TECHNICAL FIELD

The present disclosure relates to a cogeneration system.

BACKGROUND OF INVENTION

A known household cogeneration system generates electric power by using a fuel battery, recovers heat discharged from the fuel battery, and uses the recovered heat to heat municipal water and supply the heated water (see Patent Literature 1).

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2002-298863

SUMMARY

Problem to be Solved

In a cogeneration system using a fuel battery, it has been difficult to provide the heat required to heat the hot water to be supplied with the recovered heat alone, so that it is necessary to install a water heater to further heat the hot water.

Therefore, in view of the problems of the conventional techniques described above, the present disclosure provides a cogeneration system that can provide more heat to the medium as required.

Solution to Problem

In one embodiment, (1) a cogeneration system includes: a fuel battery, a heat supply channel, and a first heat exchange portion. The heat supply channel causes a medium that recovers heat generated by the fuel battery to flow therein. The first heat exchange portion is positioned close to the outer side of the fuel battery or positioned within the fuel battery to cause the medium circulating in the waste heat recovery channel to recover the heat generated by the fuel battery.

(2) The cogeneration system according to above (1) further includes: a second heat exchange portion that exchanges heat between an exhaust gas of the fuel battery and the medium flowing in the heat supply channel.

(3) In the cogeneration system according to above (2), in the heat supply channel, the first heat exchange portion is positioned on a downstream side of the second heat exchange portion.

(4) In the cogeneration system according to above (2) or (3), the heat supply channel includes a branch channel that is positioned on a downstream side of the first heat exchange portion and that includes a heat dissipation portion.

(5) In the cogeneration system according to above (4), the branch channel is further connected to an upstream side of the second heat exchange portion in the heat supply channel.

(6) In the cogeneration system according to above (4) or (5), the heat dissipation portion is positioned in a discharge channel of the exhaust gas of the second heat exchange portion.

(7) In the cogeneration system according to any one of above (1) to (6), the fuel battery further includes a housing and a reformer. The reformer is housed in the housing, and a channel of the medium in the first heat exchange portion is provided within the housing, or provided close to the housing on the outside of the housing.

(8) The cogeneration system according to above (7) further includes: a heat-shielding mechanism that suppresses heat transferred from at least one of the reformer and the fuel battery cell to the channel in the first heat exchange portion.

(9) In the cogeneration system according to above (7), the channel of the first heat exchange portion comes into contact with the outer side of the housing.

(10) In the cogeneration system according to any one of above (1) to (9), the fuel battery includes a storage portion, an exhaust gas channel, and a heat-insulating material. The fuel battery cell is disposed in the storage portion. An exhaust gas discharged from the fuel battery cell flows through the exhaust gas channel. The heat-insulating material is disposed in contact with the exhaust gas channel and separates the storage portion from the exhaust gas channel. Within the fuel battery, the heat supply channel in the first heat exchange portion is provided in contact with the exhaust gas channel and is at least partially buried in the heat-insulating material.

(11) In the cogeneration system according to above (10), the exhaust gas channel includes, on a downstream side, a drain portion that discharges water contained in the exhaust gas and includes, on an upstream side of the drain portion, a discharge portion that discharges exhaust contained in the exhaust gas.

(12) The cogeneration system according to above (11) further includes: an oxygen-containing gas channel which is provided close to the exhaust gas channel and through which an oxygen-containing gas to be supplied to the fuel battery cell flows, in which an introduction portion connected to the oxygen-containing gas channel is positioned between the drain portion and the discharge portion.

(13) In the cogeneration system according to any one of above (10) to (12), a combustion catalyst is disposed within the storage portion or disposed upstream of the heat exchange portion in the exhaust gas channel.

(14) The cogeneration system according to any one of above (10) to (13) further includes: a control device that controls fuel utilization rate to decrease or air utilization rate to increase in the fuel battery when the medium flows in the first heat exchange portion.

Advantageous Effect

The cogeneration system of the present disclosure configured as described above can efficiently provide the heat required for the medium.

DESCRIPTION OF EMBODIMENTS

Embodiments of a cogeneration system to which the present disclosure is applied will be described below with reference to the drawings. In each drawing, identical or equivalent components are denoted by the same reference signs. In the following description of embodiments, explanation for identical or equivalent components will either be omitted or briefed as needed. Note that the drawings are schematic. The dimensional proportions and the like in the drawings do not necessarily match those in reality.

As illustrated inFIG.1, a cogeneration system100according to a first embodiment of the present disclosure includes a fuel battery15, a heat supply channel18, and a first heat exchange portion19. The cogeneration system100is installed in a home, for example. The cogeneration system100may further include a second heat exchange portion20and a heat-shielding mechanism, which is to be described later.

The fuel battery15generates electric power by using a raw fuel gas, air, and water. The fuel battery15generates heat during operation to generate electric power. The heat generated by the fuel battery15is recovered by using a medium. The heat supply channel18supplies heat to the area where the heat supply channel18is disposed by causing the medium to flow through it.

The fuel battery15may include at least one of a reformer and a cell stack (fuel battery cell). The fuel battery15may be a fuel cell module that contains the reformer and the cell stack within a housing. The reformer produces a fuel such as hydrogen by generating a steam reforming reaction between a gas supplied as the raw fuel and water. The cell stack is, for example, a solid oxide fuel cell (SOFC) and generates electric power through an electrochemical reaction using an oxidant such as oxygen contained in the air and the fuel produced by the reformer. Further, the cell stack produces water through the electrochemical reaction. Unreacted fuel and unreacted oxidant discharged from the cell stack are combusted to provide energy for the steam reforming reaction in the reformer. The water discharged from the cell stack is discharged from the fuel battery15in a high-temperature gaseous state together with the combustion gas generated by the combustion of the unreacted fuel and the unreacted oxidant. The cell stack may be a polymer electrolyte fuel cell (PEFC). In such a case, any appropriate configurations may be used as the other configurations.

The exhaust gas discharged from the fuel battery15may include the combustion gas and the gaseous water. The exhaust gas discharged from the fuel battery15may exchange heat with the medium by using the second heat exchange portion20, which is to be described later. The exhaust gas cooled by the heat exchange may be separated into gaseous exhaust gas and condensed liquid water by a gas-liquid separator23. The separated exhaust gas may be discharged outside the cogeneration system100. The separated water may be sent to the fuel battery15as the water for the steam reforming reaction.

The heat supply channel18flows the medium to the first heat exchange portion19to recover heat. The heat supply channel18may flow the medium to the second heat exchange portion20to recover heat. The medium is a fluid with a high specific heat, such as water.

The first heat exchange portion19causes the medium flowing in the heat supply channel18to recover the heat generated by the fuel battery15. As illustrated inFIG.2, when the medium flowing in the heat supply channel18flows through a pipeline (the channel of the medium)25, the first heat exchange portion19recovers heat by transferring heat from the outer surface to the medium.

The first heat exchange portion19may be positioned close to the outer side of the fuel battery15(housing) or within the fuel battery15(within the housing). When positioned close to the outer side of the fuel battery15, the first heat exchange portion19may be disposed in contact with the outer side of the fuel battery15or disposed without being in contact with the fuel battery in a range where the heat from the fuel battery can be received. When positioned within the fuel battery15, the first heat exchange portion19may be disposed around at least one of the reformer and the cell stack without interposing a heat-insulating material. For example, as illustrated inFIGS.2to5, the first heat exchange portion19may be formed by providing the pipeline25, through which the medium flowing in the heat supply channel18passes, around at least one of a reformer26and a cell stack27. In such a case, the pipeline25may be provided around at least one of the reformer26and the cell stack27without interposing a heat-insulating material. In the present disclosure, the term “heat-insulating material” means a material that avoids heat transfer, and examples of the heat-insulating material include a fibrous heat-insulating material such as glass wool and a foamed heat-insulating material such as resin foam. Therefore, in the present disclosure, a heat-shielding mechanism31and a housing29to be described later are not included in the heat-insulating material. The term “without interposing a heat-insulating material” means that there is no material with heat insulating property positioned on a straight line connecting, in the shortest distance, the surface of at least a part of the pipeline25and the surface of at least one of the reformer26and the cell stack27. Thus, even a configuration in which a packing28made of material with heat insulating property is positioned closer to the reformer26or the cell stack27than to the pipeline25can function as the first heat exchange portion19.

The housing29may be provided to house at least one of the reformer26and the cell stack27. The housing29may be made of metal. For example, the housing29may cover three sides of the reformer26and the cell stack27. As illustrated inFIG.5, the pipeline25of the medium in the first heat exchange portion19may be positioned close to the outer side of the housing29in a range where the heat of at least one of the reformer26and the cell stack27can be transferred.

As illustrated inFIG.6, the pipeline25may extend horizontally along the longitudinal surface of the housing29and fold back on the lateral surface to form a meandering shape. Therefore, the pipeline25can extend long on the outer surface of the housing29. An inlet and an outlet of the pipeline25on the outer surface of the housing29may be oriented horizontally.

As illustrated inFIG.7, the pipeline25may be provided within the housing29. More specifically, the housing29may be made by pressing two plates so that the pipeline25is formed between the plates. The inlet and the outlet of the pipeline25from the inside of the housing29may face downward. The pipeline25may extend horizontally along the inner side of the longitudinal surface of the housing29and fold back on the inner side of the lateral surface to form a meandering shape. In the configuration where the pipeline25is provided within the housing29, a heat-insulating material30may be positioned between the pipeline25and the housing29, as illustrated inFIGS.2and3.

As illustrated inFIGS.2to4, the cogeneration system100may include heat-shielding mechanisms31aand31b. As illustrated inFIGS.2to4, the heat-shielding mechanism31amay include at least one heat-shielding plate31s. The heat-shielding mechanism31aincludes, for example, a plurality of heat-shielding plates31s. The heat-shielding plate31smay be rectangular. The heat-shielding plate31smay be rotatably supported on an axis on one side of the rectangle. The heat-shielding plate31smay be switchable between a closed state and an open state. In other words, the heat-shielding mechanism31ais a blind-like component. The heat-shielding plate31smay block between the pipeline25and the reformer26or the cell stack27in the closed state. The heat-shielding plate31smay open between the pipeline25and the reformer26or the cell stack27in the open state.

The heat-shielding mechanism31acontrols the radiation of heat from at least one of the reformer26and the cell stack27to the pipeline25in the first heat exchange portion19. More specifically, as illustrated inFIG.2, the heat-shielding mechanism31ain the closed state blocks the radiation from the reformer26or the cell stack27and a part of the convection of the surrounding gas from the reformer26or the cell stack27. Only the convection that bypasses the heat-shielding mechanism31amay reach the pipeline25. As illustrated inFIG.4, the heat-shielding mechanism31ain the open state allows the convection of the surrounding gas from the reformer26or the cell stack27to pass through, while blocking a part of the radiation from the reformer26or the cell stack27.

Note that the heat-shielding mechanism31amay be provided with a closing plate31c, as illustrated inFIG.3, in at least one of a position above the highest position of the pipeline25and a position below the lowest position of the pipeline25. When the heat-shielding plate31sis in the closed state, the closing plate31ccloses at least one of the vertical sides of the space between the heat-shielding plate31sand the pipeline25. In such a case, the closing plate31ccan stop or reduce the flow of high-temperature gas by closing at least one of the vertical sides of the space between the heat-shielding plate31sand the pipeline25. The closing plate31c, like the heat-shielding plate31s, may include a plurality of plates each supported in a rotatable manner and may be switchable between the closed state and the open state. The closing plate31cmay be a single plate.

As illustrated inFIG.5, the heat-shielding mechanism31bmay be configured by positioning the pipeline25outside of the housing29. The pipeline25, which functions as the channel of the first heat exchange portion19, can come into contact with the outer side of the housing29.

More specifically, the pipeline25is attached to a plate-shaped movable member32m. The movable member32mmay translate to be separated from or come close to the housing29. The movable member32min contact with the housing29is indicated by a solid line, and the movable member32mseparated from the housing29is indicated by a dotted line. The housing29is heated to about 400° C. to about 600° C., for example, by radiation from the reformer26or the cell stack27or by convection of the exhaust gas. When the movable member32mis in contact with the housing29, the pipeline25attached to the movable member32mis heated more strongly. On the other hand, when the movable member32mis separated from the housing29, the heating to the pipeline25is weakened.

The operation of the heat-shielding mechanism for heat transfer adjustment may be realized by a motor. The operation of the heat-shielding mechanism may be realized by a bimetal obtained by laminating plates with different coefficients of thermal expansion. The operation of the heat-shielding mechanism may be realized by a thermoelement containing wax. The operation of the heat-shielding mechanism is, for example, switching the state of the heat-shielding mechanism31aor displacing the movable member32m.

The operation of the heat-shielding mechanism may be realized by an elastic member and the pressure of the heat medium. Specific examples of a heat-shielding mechanism that can be based on the elastic member and the pressure of the heat medium are described below. Referring toFIGS.6and8, the pipeline25may include a first portion25n, a second portion25w, and a spring (elastic body)32e. The first portion25nmay be fixed to the housing29or may be positioned without being in contact with the housing29in a range where the heat from the fuel battery can be received. The second portion25wmay extend horizontally along the longitudinal surface of the housing29. The first portion25nand the second portion25wmay be cylindrical. The diameter of the first portion25nmay be smaller than the diameter of the second portion25w. Alternatively, the diameter of the first portion25nmay be larger than the diameter of the second portion25w. One of the first portion25nand the second portion25wmay be connected, on the lateral surface of the housing29, to the other of the first portion25nand the second portion25win a state in which the aforesaid other is slidably inserted along the axial direction into the aforesaid one. The spring32emay be provided to bias the second portion25wtoward the first portion25n. The spring32emay be wound around the first portion25n.

When the spring32econtracts, the second portion25wmay come into contact with the longitudinal surface of the housing29directly or via a movable member to be described later. When the spring32econtracts, the second portion25wmay be close to the longitudinal surface of the housing29in a range where the heat from a fuel battery16can be received. On the other hand, when the spring32eextends, the second portion25wmay be separated from the longitudinal surface of the housing29.

The pipeline25is subjected to the static pressure of the medium in the pipeline25. The static pressure exerts a force in the direction that causes the spring32eto extend. Thus, in response to the increase in static pressure, the medium exerts a force on the second portion25wto cause the spring32eto extend. When the static pressure decreases, the force exerted by the medium on the pipeline25becomes weaker. The force exerted by the medium to separate the second portion25wof the pipeline25from the first portion25nmay also become weaker. Thus, the spring32emay contract, so that the second portion25wis brought close to the longitudinal surface of the housing29. In contrast, when the static pressure increases, the force exerted by the medium to separate the second portion25wof the pipeline25from the first portion25nmay become stronger. Thus, the spring32emay extend to separate the second portion25wfrom the longitudinal surface of the housing29.

The pipeline25may be fixed to the movable member32m, which is a connecting plate facing the longitudinal surface of the housing29. Such a configuration can avoid a situation in which excessive load is applied to the pipeline25. An elastic body may be provided between the movable member32mand the housing29. Further, a part of the pipeline25may be the elastic body. With such a configuration, by opening a hot water delivery valve33, the elastic body of the pipeline25may contract to bring the pipeline25into contact with the longitudinal surface of the housing29. By opening the hot water delivery valve33, the elastic body of the pipeline25may contract to bring the pipeline25close to the longitudinal surface of the housing29in a range where the heat from the fuel battery16can be received. By closing the hot water delivery valve33, the elastic body of the pipeline25may extend to separate the pipeline25from the longitudinal surface of the housing29.

For power generation in the fuel battery15, the temperature of each of the reformer26and the cell stack27needs to be maintained within an ideal temperature range. By using the first heat exchange portion19including the configuration described above, the reformer26and the cell stack27are cooled by the heat medium. Therefore, the fuel battery15generates not only the heat needed to generate electric power, but also the heat to heat the heat medium. In such a configuration, when the supply of the medium is stopped, the reformer26and the cell stack27are cooled by the heat exchange in the first heat exchange portion19, while heating of the heat medium is not required. On the other hand, since the heat-shielding mechanism can adjust the amount of heat exchanged in the first heat exchange portion19, cooling of the reformer26and the cell stack27can be suppressed when heating of the heat medium is not required. Thus, by using the heat-shielding mechanism, since the amount of the raw fuel gas to be supplied to the fuel battery15can be reduced when heating of the heat medium is not required, the power generation efficiency can be increased.

As illustrated inFIG.1, the second heat exchange portion20is, for example, a heat exchanger. The second heat exchange portion20exchanges heat between the exhaust gas discharged from the fuel battery15and the medium flowing in the heat supply channel18. The second heat exchange portion20may be positioned on the upstream side of the first heat exchange portion19in the heat supply channel18. The temperature of the exhaust gas discharged from the fuel battery15is generally lower than the temperature around the reformer26and the cell stack27(for example, the temperature of the exhaust gas discharged from the fuel battery15is from about 200° C. to about 300° C.). Thus, the second heat exchange portion20functions as a preheater of the medium with respect to the first heat exchange portion19.

The heat supply channel18is, for example, a hot water supply channel. In the heat supply channel18, on the upstream side of the second heat exchange portion20, a first flow regulating valve43may be provided to adjust the supply amount of the medium. In the heat supply channel18, the hot water delivery valve33may be provided on the downstream side of the first heat exchange portion19. The pressure of the medium may be adjusted higher at the upstream end of the heat supply channel18than at the downstream end. For example, the upstream end of the heat supply channel18may be connected to a high-pressure clean water pipe. The hot water delivery valve33opens to allow the medium to flow to the downstream side. When the hot water delivery valve33is open, the static pressure of the medium in the pipeline25on the upstream side of the hot water delivery valve33decreases. When the hot water delivery valve33is closed, the static pressure of the medium in the pipeline25on the upstream side of the hot water delivery valve33is lower than when the hot water delivery valve33is open. Therefore, the static pressure of the medium in the pipeline25may be adjusted by opening and closing the hot water delivery valve33. The heat-shielding mechanism described above may be operated by adjusting the static pressure of the medium in the pipeline25. More specifically, when the hot water delivery valve33is open (seeFIG.6), the spring32emay contract, so that the second portion25wapproaches the longitudinal surface of the housing29. When the hot water delivery valve33is closed (seeFIG.8), the spring32emay extend to separate the pipeline25from the longitudinal surface of the housing29.

A low-temperature delivery channel34may branch off from the heat supply channel18between the first flow regulating valve43and the second heat exchange portion20. The low-temperature delivery channel34may bypass the second heat exchange portion and the first heat exchange portion. A second flow regulating valve45may be provided in the low-temperature delivery channel34to adjust the supply amount of the medium. By adjusting the flow rate of the medium branching out into the low-temperature delivery channel34with the second flow regulating valve45, the temperature of the medium to be delivered from the heat supply channel18can be adjusted. By mixing the low-temperature medium flowing in the low-temperature delivery channel34with the high-temperature medium flowing in the heat supply channel18, a medium that is cooler than the heat supply channel18can be delivered. More specifically, the heat supply channel18heats the clean water supplied from outside the facility where the cogeneration system100is installed by flowing the clean water to a heat exchange portion, such as the first heat exchange portion19and supplies the hot water to a consumer facility, for example.

As illustrated inFIG.9, a cogeneration system200according to a second embodiment of the present disclosure includes configurations similar to those of the cogeneration system100. Hereinafter, the same configurations as in the cogeneration system100will not be described again, and configurations that differ from the cogeneration system100will be described.

The heat supply channel18branches, on the downstream side of the fuel battery15, into a hot water delivery channel18aand a circulation channel18b.

The circulation channel18bmay be provided with a heat dissipation portion13. The heat dissipation portion13is, for example, a radiator, which dissipates heat from the medium by exchanging heat between the air supplied by a blower and the medium.

A pump24may be provided on the downstream side of the heat dissipation portion13. The pump24may boost the pressure so that the medium flows from the heat dissipation portion13to the second heat exchange portion20.

The second heat exchange portion20may be positioned on the downstream side of the pump24. The first heat exchange portion19may be positioned on the downstream side of the second heat exchange portion20.

As illustrated inFIG.10, a cogeneration system300according to a third embodiment of the present disclosure includes configurations similar to those of the cogeneration system200. Hereinafter, the same configurations as in the cogeneration system200will not be described again, and configurations that differ from the cogeneration system200will be described.

The circulation channel18bmay be provided with a heat dissipation portion14. The heat dissipation portion14is, for example, a radiator. The heat dissipation portion14is positioned in a discharge channel of the exhaust gas of the second heat exchange portion20. More specifically, the heat dissipation portion14is positioned in the discharge channel of the exhaust gas of the second heat exchange portion20, at a position downstream from the gas-liquid separator23.

A pump21may be provided on the downstream side of the heat dissipation portion14. The circulation channel18bmay merge, on the downstream side of the pump21, with the heat supply channel18. The pump21may boost the pressure so that the medium flows from the heat dissipation portion14to the second heat exchange portion20.

The cogeneration systems100,200and300of the present embodiments with the above configuration each include the first heat exchange portion19that is positioned close to the outer side of the fuel battery15or within the fuel battery15to allow the medium flowing in the heat supply channel18to recover the heat generated by the fuel battery15. In a typical cogeneration system using a fuel battery, waste heat is recovered by exchanging heat between the exhaust gas of the fuel battery and the medium, but it is difficult to heat the medium sufficiently, so that it is difficult to supply a large amount of hot water temporarily. In a cogeneration system that recovers waste heat from exhaust gas but has difficulty supplying a large amount of hot water temporarily, a water heater needs to be installed to meet the demand for supplying a large amount of hot water temporarily. On the other hand, in the cogeneration systems100,200and300of the present embodiments with the above-described configuration, since the fuel battery15itself generally operates at a higher temperature than the exhaust gas, a larger amount of heat can be recovered than in the configuration in which the waste heat is recovered from the exhaust gas. Thus, the cogeneration systems100,200and300can supply a large amount of hot water temporarily. Therefore, in the cogeneration systems100,200and300, since it is possible to supply a large amount of hot water temporarily, it is not necessary to install a water heater. Thus, the cogeneration systems100,200and300can be made smaller in size.

The cogeneration systems100,200and300of the present embodiments each include the second heat exchange portion20that exchanges heat between the exhaust gas of the fuel battery15and the medium flowing in the heat supply channel18. With such a configuration, in the cogeneration systems100,200and300, the temperature of the exhaust gas of the fuel battery15can be lowered.

In the heat supply channel18of the cogeneration systems100,200and300according to the present embodiments, the first heat exchange portion19is positioned on the downstream side of the second heat exchange portion20. With such a configuration, after being heated in the second heat exchange portion20, the medium flows into the first heat exchange portion19where the heat generated by the fuel battery15is recovered. Therefore, a situation in which the low-temperature medium takes a large amount of heat away from the fuel battery15can be avoided. Thus, the power generation efficiency of the fuel battery15can be maintained.

The heat supply channel18of the cogeneration systems200and300according to the present embodiments includes the circulation channel18bas a branch channel that is located on the downstream side of the first heat exchange portion19and includes the heat dissipation portions13and14. With such a configuration, the cogeneration systems200and300can cool the heat accumulated in the medium when the hot water is not being supplied. Thus, the cogeneration systems200and300can avoid extreme reduction in the recovery amount of the water from the exhaust gas.

The heat dissipation portion14of the heat supply channel18of the cogeneration system300according to the present embodiment is positioned in the discharge channel of the exhaust gas of the second heat exchange portion20. With such a configuration, the need for a blower or the like to cool the heat dissipation portion14is eliminated, so that it is possible to simplify the configuration and reduce manufacturing cost.

The fuel battery15of the cogeneration systems100,200and300according to the present embodiments is further provided with the housing29and at least one of the reformer26and the cell stack27housed in the housing29, and the channel of the medium in the first heat exchange portion19is provided within the housing29or close to the housing29on the outside of the housing29. With such a configuration, in the first heat exchange portion19, the medium can be close to the high-temperature area of the housing29or the area surrounding the high-temperature area. Therefore, the medium can be heated more efficiently in the first heat exchange portion19.

Further, the cogeneration systems100,200and300according to the present embodiments include a heat-shielding mechanism31that suppresses heat transfer from at least one of the reformer26and the cell stack27to the pipeline25, which functions as a channel in the first heat exchange portion19. With such a configuration, excessive heating of the pipeline25can be suppressed.

The pipeline25, as the channel of the first heat exchange portion19of the cogeneration systems100,200and300according to the present embodiments, can come into contact with the outer side of the housing29. With such a configuration, the pipeline25can be positioned on the outer side of the housing29while the pipeline25(i.e., the medium) can be heated more strongly.

FIG.11is a schematic view illustrating a configuration of a fuel battery applied to a cogeneration system according to a fourth embodiment.

A fuel battery416of the cogeneration system generates electric power by a fuel battery cell490(cell stack) and uses the heat generated to raise the temperature of the medium.

The fuel battery416includes the fuel battery cell490, a storage portion429, an exhaust gas channel495, and a heat-insulating material430. The fuel battery416includes an oxygen-containing gas channel494. The fuel battery416may be provided with a reformer426.

The fuel battery cell490is disposed in the storage portion429of the fuel battery416. In the present embodiment, the fuel battery416contains the reformer426and the fuel battery cell490in the storage portion429. The storage portion429may be included in a housing431. Specifically, the storage portion429may be a part of the inner wall of the housing431and a part of the heat-insulating material430to be described later. The aforesaid a part of the inner wall of the housing431and a part of the heat-insulating material may define the inner space of the storage portion429. More specifically, the housing431, which is made of metal, may define a part of the boundary of the storage portion429. For example, the housing431may define the remaining three sides (the sides not adjacent to the exhaust gas channel495) of the storage portion429, the cross-section of which is rectangular. The heat-insulating material430may define the other part of the boundary of the storage portion429. For example, the heat-insulating material430may define one side of the cross-section of the storage portion429. The reformer426produces a fuel such as hydrogen by generating a steam reforming reaction between a gas supplied as the raw fuel and water. The fuel battery cell490, which is, for example, a solid oxide fuel cell (SOFC), generates electric power through an electrochemical reaction using an oxidant, such as oxygen contained in the air, and the fuel produced by the reformer426. The fuel battery416generates heat during the operation to generate electric power. The fuel battery cell490produces water through the electrochemical reaction. Unreacted fuel and unreacted oxidant discharged from the fuel battery cell490are combusted to provide energy for the steam reforming reaction in the reformer426. The water discharged from the fuel battery cell490is discharged from the fuel battery416in a high-temperature gaseous state together with the combustion gas generated by the combustion of the unreacted fuel and the unreacted oxidant. The heat generated during the operation for power generation and the heat of the combustion are recovered by the medium as heat generated by the fuel battery416. Here, the fuel battery cell490may be a polymer electrolyte fuel cell (PEFC).

In the fuel battery416, the exhaust gas discharged from the fuel battery cell490flows through the exhaust gas channel495to be discharged. The exhaust gas includes at least one selected from the group consisting of the fuel gas that has not been used to generate electric power, the combustion gas (exhaust, gaseous) generated by the combustion of the fuel gas discharged from the fuel battery cell490, and the gaseous water. In the fuel battery416, the heat-insulating material430is disposed in contact with the exhaust gas channel495, and separates the storage portion429from the exhaust gas channel495. The heat-insulating material430is a material that avoids heat transfer and may be, for example, a fibrous heat-insulating material such as glass wool or a foamed heat-insulating material such as resin foam.

The exhaust gas channel495includes, on the downstream side, a drain portion493that discharges the water contained in the exhaust gas. The exhaust gas channel495includes, on the upstream side of the drain portion493, a discharge portion491that discharges the exhaust contained in the exhaust gas. The oxygen-containing gas channel494is provided close to the exhaust gas channel495, and an oxygen-containing gas to be supplied to the fuel battery cell490flows through the oxygen-containing gas channel494. An introduction portion492connected to the oxygen-containing gas channel494is positioned between the drain portion493and the discharge portion491. The exhaust gas flowing through the exhaust gas channel495is cooled by the oxygen-containing gas in the nearby oxygen-containing gas channel494. From the cooled exhaust gas, liquid water (drain) generated by condensation of moisture is discharged from the drain portion493, and gas is discharged from the discharge portion491. The water separated and discharged from the drain portion493may be sent to the fuel battery416as the water to be used for the steam reforming reaction in the reformer426. With such a configuration of the fuel battery416, since the water to be used for the steam reforming reaction can be separated from the exhaust gas without providing a gas-liquid separator, the system can be reduced in size as a whole. In other words, inFIGS.1,9and10, the gas-liquid separator23can be eliminated.

The exhaust gas is cooled by heat exchange with the oxygen-containing gas in the oxygen-containing gas channel494. On the other hand, the oxygen-containing gas is heated by heat exchange with the exhaust gas. Since the heated oxygen-containing gas flows into the reformer426and the fuel battery cell490, cooling of the reformer426and the fuel battery cell490can be reduced. Therefore, the temperature of the fuel battery cell490and the reformer426can be kept high. Thus, the power generation efficiency of the fuel battery cell490and the reformer426can be maintained.

A heat supply channel425is positioned within the fuel battery416(within the storage portion429). In the present embodiment, the heat supply channel425is provided in contact with the exhaust gas channel495, and the medium flows through the heat supply channel425. The heat supply channel425is at least partially buried in the heat-insulating material430. At least a part of the heat supply channel425may be exposed to the exhaust gas channel495. As illustrated inFIG.11, in the present embodiment, the heat supply channel425is buried in the heat-insulating material430. The exhaust gas channel495and the heat supply channel425provided in contact with the exhaust gas channel495constitute a first heat exchange portion419corresponding to the first heat exchange portion19described in the first embodiment to third embodiment. With such a configuration of the fuel battery416, since the heat generated by the fuel battery416in the high-temperature interior of the storage portion429can be efficiently recovered by the medium, effective use of heat becomes possible.

Here, a combustion catalyst496may be used to promote combustion of the exhaust gas. In the fuel battery416according to the present embodiment, the combustion catalyst496is disposed within the storage portion429, or disposed upstream of the heat supply channel425in the exhaust gas channel495. Here, as another example, the fuel battery416can be configured without using the combustion catalyst496. When the combustion catalyst496is not used, a combustion distance L between the combustion portion and the reformer426is preferably large so that the air amount is sufficient, as illustrated inFIG.12.

As illustrated inFIG.13, a cogeneration system400according to an embodiment of the present disclosure includes the fuel battery416described above. The cogeneration system400is a hot water supply system. In other words, in the fuel battery416, the medium flowing in the heat supply channel425is water to be supplied as hot water. For example, the cogeneration system400may include a heating system. In such a case, the medium flowing in the heat supply channel425may circulate through the heating system, and the medium may be water, an antifreeze, or the like. In other words, the medium flowing in the heat supply channel425may be supplied directly or indirectly to the user.

The cogeneration system400includes a plurality of channels through which water flows, the fuel battery416including the heat supply channel425, and a control device435. The cogeneration system400may include a cooling and heating device422. The cogeneration system400is installed in a home, for example.

The cogeneration system400according to the present embodiment includes, as the plurality of channels through which water flows, an external water channel81, a hot water supply channel412, a heat exchange channel482, and a water channel484.

The external water channel481is a channel through which water supplied from outside the cogeneration system400flows. In the external water channel481, a temperature sensor455may be provided to measure the temperature of the water flowing into the external water channel481. Further, a flow rate sensor462may be provided to measure the amount of the water flowing into the external water channel481. The external water channel481may be provided with a first flow regulating valve443to adjust the supply amount of the water.

The hot water supply channel412is a channel that supplies heated water (hot water) to the outside. A temperature sensor456may be provided to measure the temperature of the water at the outlet of the hot water supply channel412.

The heat exchange channel482is a channel that connects the external water channel481and the hot water supply channel412and passes through the heat supply channel425.

The water channel484is another channel that connects the external water channel481and the hot water supply channel412. The water channel484may be provided with a second flow regulating valve446that adjusts the amount of the water passing through the water channel484.

In the cogeneration system400, the water from the hot water supply channel412may flow through the water channel484into the external water channel481to circulate. A circulation pump440may be provided in the external water channel481to boost the pressure to circulate the water.

The cooling and heating device422is provided in the vicinity of the hot water supply channel412to heat or cool the water flowing in the hot water supply channel412. The cooling and heating device422may be, for example, a burner, an electric heater or the like. The cooling and heating device422may be, for example, a burner including a fuel injection line that supplies a gaseous fuel and an air supply line that forcibly draws in the outside air by using a blower and supplies the drawn air. The cooling and heating device422mixes, at the ignition port, the gaseous fuel and the outside air, and combusts the mixture. The water is heated by the combustion of the cooling and heating device422. Further, the cooling and heating device422can generate wind with a blower to cool the water. With the cooling and heating device422, the temperature of the hot water to be supplied to the outside can be further appropriately adjusted.

The control device435includes one or more processors and memories. The processors may include a general-purpose processor that is loaded with specific programs to perform specific functions and a dedicated processor dedicated to specific processing. The dedicated processors may include an application specific integrated circuit (ASIC). The processors may include a programmable logic device (PLD). The PLD may include a field-programmable gate array (FPGA). The control device35may be either a system-on-a-chip (SoC) or a system in a package (SiP) in which one or more processors corporate with each other. The control device435may control the components of the cogeneration system400, such as the circulation pump440, the first flow regulating valve443, the second flow regulating valve446, and the cooling and heating device422. In the present embodiment, the control device435controls the operation of the fuel battery416.

The control device435controls the components of the cogeneration system400, including the fuel battery416, in response to the demand for hot water. For example, when there is a continuous demand for hot water, the control device435controls the first flow regulating valve443and the second flow regulating valve446to flow the medium (water) in the heat supply channel425. At this time, the control device435controls the fuel utilization rate to decrease or the air utilization rate to increase in the fuel battery416. Specifically, the control device435may cause the fuel utilization rate to decrease by increasing the fuel supply rate, and cause the fuel that remains unconsumed by the fuel battery416to be combusted. Such control makes it difficult for the temperature within the fuel battery416to drop, so that the heat can be used effectively.

With the above-described configuration, the fuel battery416and the cogeneration system400according to the present embodiment can make effective use of heat and achieve size reduction. Therefore, the fuel battery416and the cogeneration system400according to the present embodiment are suitable for household cogeneration systems requiring compactness and size reduction.

Note that the drawings used in the description of the embodiments according to the present disclosure are schematic drawings, and the dimensional proportions and the like in the drawings do not necessarily match those in reality.

Although the embodiments pertaining to the present disclosure have been described based on the drawings and examples, it is to be noted that various variations and changes may be made by those who are ordinarily skilled in the art based on the present disclosure. Thus, it is to be noted that these variations or changes are included within the scope of the present disclosure. For example, functions and the like included in each component or the like can be rearranged without logical inconsistency, and a plurality of components or the like can be combined into one or divided.

All the components described in the present disclosure and/or all the disclosed methods or all the processing steps may be combined based on any combination except for the combination where these features are exclusive with each other. Further, each of the features described in the present disclosure may be replaced with an alternative feature for achieving the same purpose, an equivalent purpose, or a similar purpose, unless explicitly denied. Therefore, each of the disclosed features is merely an example of a comprehensive series of identical or equal features, unless explicitly denied.

The embodiments according to the present disclosure are not limited to any of the specific configurations in the embodiments described above. The embodiments according to the present disclosure can be extended to all the novel features described in the present disclosure or a combination thereof, or to all the novel methods described in the present disclosure, the processing steps, or a combination thereof.

The descriptions such as “first” and “second” in the present disclosure are identifiers for distinguishing corresponding configurations. Configurations distinguished by the descriptions such as “first” and “second” in the disclosure can exchange numbers in the corresponding configurations. For example, the first heat exchange portion can exchange “first” and “second”, which are identifiers, with the second heat exchange portion. The exchange of identifiers takes place at the same time. Even after exchanging identifiers, the corresponding configuration is distinguished. The identifier may be deleted. The configuration with the identifier deleted is distinguished by a reference sign. It should not be used as a basis for interpreting the order of the corresponding configurations and the existence of identifiers with lower numbers, based on the description of identifiers such as “first” and “second” in this disclosure.

The embodiments according to the present disclosure are not limited to any of the specific configurations in the embodiments described above. The embodiments according to the present disclosure can be extended to all the novel features described in the present disclosure or a combination thereof.

REFERENCE SIGNS