JP7450442B2 - Fuel cell exhaust heat utilization system and fuel cell system - Google Patents

Description

The present invention relates to a fuel cell exhaust heat utilization system and a fuel cell system that utilize the exhaust heat of a fuel cell.

In recent years, from the viewpoint of environmental issues, energy efficiency, etc., polymer electrolyte fuel cells (PEFC), which have a low operating temperature for fuel cell reactions, are sometimes used as household fuel cells. Such an exhaust heat utilization system using fuel cells consists of a polymer electrolyte fuel cell that generates electricity and heat, a hot water storage tank that stores the exhaust heat as hot water, and a cooling water circulation channel that circulates cooling water through the fuel cell. , a hot water circulation flow path that circulates water in the hot water storage tank, and a heat exchanger that exchanges heat between the cooling water flowing through the cooling water circulation flow path and the water flowing through the hot water circulation flow path (for example, Patent Document 1). In such an exhaust heat utilization system, exhaust heat from the polymer electrolyte fuel cell is transmitted to a hot water storage tank via cooling water flowing through a cooling water circulation path, and is stored in the hot water storage tank as hot water. Here, by utilizing the exhaust heat of the polymer electrolyte fuel cell, the temperature of the hot water stored in the hot water storage tank is approximately 40°C.

In the exhaust heat utilization system shown in Patent Document 1, exhaust heat from a fuel cell is used for floor heating and heating a desiccant air conditioner. In addition, in the cogeneration system shown in Patent Document 2, the waste heat of the fuel cell of the power generation unit is determined in advance by determining the order of the places where the waste heat is used (floor heating, bathroom heating dryer, bathtub, washing machine, etc.). There is.

Japanese Patent Application Publication No. 2005-265293 Japanese Patent Application Publication No. 2015-209991

The exhaust heat utilization system of Patent Document 1 is equipped with a solar heat collection device as an auxiliary heat source, and when the amount of heat stored in the hot water storage tank is not sufficient for the waste heat usage destination, the hot water in the hot water storage tank is drained by the solar heat collection device. heated. In addition, the cogeneration system of Patent Document 2 is equipped with an auxiliary heat source, and when the amount of heat stored in the hot water storage tank is not sufficient for the exhaust heat utilization destination, the auxiliary heat source performs combustion operation to heat the hot water in the hot water storage tank. be done. Among the exhaust heat utilization sites, floor heating requires relatively low hot water temperature (for example, 40° C.), so it can be handled using only the exhaust heat of the fuel cell without using an auxiliary heat source. On the other hand, bathroom heater/dryers require hot water at a higher temperature (e.g. 80°C) than floor heating, so if a polymer electrolyte fuel cell is used as a fuel cell and the exhaust heat is used, the There is a high possibility that the temperature is not sufficient. Therefore, when using a bathroom heater/dryer, the exhaust heat from the fuel cell cannot be used effectively, and there is room for improvement.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a fuel cell exhaust heat utilization system and a fuel cell system that can effectively utilize the exhaust heat of the fuel cell in a bathroom heater/dryer. With the goal.

The characteristic configuration of the fuel cell exhaust heat utilization system according to the present invention is as follows:
A fuel cell that generates waste heat,
a hot water storage tank that stores waste heat from the fuel cell as hot water;
a bathroom heater/dryer capable of utilizing the heat of hot water in the hot water storage tank;
a hot water circulation flow path through which hot water in the hot water storage tank circulates;
a heating hot water circulation flow path through which hot water circulates through the bathroom heating dryer;
a first heat exchanger that exchanges heat between the hot water flowing through the stored hot water circulation flow path and the hot water flowing through the heating hot water circulation flow path;
an auxiliary heat source device that heats the hot water flowing through the stored hot water circulation flow path;
a control unit that controls the flow of hot water in the stored hot water circulation flow path and the heating hot water circulation flow path, the operation of the bathroom heating dryer, and the operation of the auxiliary heat source device ,
The bathroom heating dryer includes a second heat exchanger that exchanges heat with the hot water circulating in the heating hot water circulation flow path, and sucks air that can be heated by the second heat exchanger and circulates it in the bathroom. and a circulation fan, and is capable of executing a low temperature drying mode and a high temperature drying mode in which the circulation fan is driven to discharge heated air or unheated air into the bathroom,
The control unit includes:
When executing the low-temperature drying mode, if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the auxiliary heat source device is not used and hot water is circulated in the stored hot water circulation flow path and the heating hot water circulation flow path. If the amount of heat stored in the hot water storage tank is less than a predetermined amount of heat, executing a cool air operation that stops the circulation of hot water in the heating hot water circulation flow path ;
When executing the high temperature drying mode, if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the exhaust heat operation is executed, and if the amount of heat stored in the hot water storage tank is less than the predetermined amount of heat, the The point is to execute an auxiliary heat source operation in which the auxiliary heat source device is driven to supply hot water heated by the auxiliary heat source device to the stored hot water circulation flow path .

According to this characteristic configuration, when executing the low-temperature drying mode, the fuel cell exhaust heat utilization system executes the exhaust heat operation when the amount of heat stored in the hot water storage tank is equal to or higher than a predetermined amount of heat. If the amount of heat generated is less than a predetermined amount of heat, cool air operation is performed. Therefore, the exhaust heat of the fuel cell can be used to operate in the low temperature drying mode without using an auxiliary heat source device. As a result, the exhaust heat of the fuel cell can be effectively utilized in the fuel cell exhaust heat utilization system. In addition, when executing the high temperature drying mode, the fuel cell exhaust heat utilization system executes exhaust heat operation when the amount of heat stored in the hot water storage tank is equal to or higher than a predetermined amount of heat, and the amount of heat stored in the hot water storage tank reaches a predetermined amount. If it is less than the amount of heat, an auxiliary heat source operation is performed in which the auxiliary heat source device is driven to supply hot water heated by the auxiliary heat source device to the stored hot water circulation flow path.
When drying a bathroom using a bathroom heater/dryer, when exhaust heat operation and cool air operation are used together, heated air is not supplied to the bathroom during the cool air operation. Therefore, the longer the cool air operation takes, the longer it takes to complete the bathroom drying. Therefore. This characteristic configuration is configured to allow execution of auxiliary heat source operation using an auxiliary heat source device. Thereby, by executing the auxiliary heat source operation in place of the cool air operation as needed, bathroom drying can be completed quickly.

In this way, the fuel cell exhaust heat utilization system of this configuration can use the exhaust heat of the fuel cell as it is for the bathroom heater/dryer. For example, in polymer electrolyte fuel cells used as fuel cells, the operating temperature of the fuel cell reaction is low, and even if the waste heat is used, water can only be heated to about 40 degrees Celsius. It can be applied and used effectively. Therefore, even when a polymer electrolyte fuel cell is used as the fuel cell, the energy utilization rate can be increased by using the bathroom heater/dryer.

Further characteristic configurations of the fuel cell exhaust heat utilization system according to the present invention are as follows:
When executing the low-temperature drying mode , if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the control unit executes the exhaust heat operation, and during the execution of the exhaust heat operation, the controller When the stored amount of heat becomes less than a predetermined amount of heat, the cool air operation is executed.

According to this characteristic configuration, when the exhaust heat utilization system of the fuel cell executes the low temperature drying mode using the bathroom heating/dryer, if the amount of heat stored in the hot water storage tank is equal to or higher than the predetermined amount of heat, the exhaust heat operation is started. When the amount of heat stored in the hot water storage tank becomes less than a predetermined amount of heat during the exhaust heat operation, the cool air operation is executed. Therefore, the exhaust heat of the fuel cell can be used to operate in the low temperature drying mode without using an auxiliary heat source device. As a result, the exhaust heat of the fuel cell can be effectively utilized in the exhaust heat utilization system.

Further characteristic configurations of the fuel cell exhaust heat utilization system according to the present invention are as follows:
When executing the low-temperature drying mode , if the amount of heat stored in the hot water storage tank is less than a predetermined amount of heat, the control unit executes the cool air operation, and during the execution of the cool air operation, the amount of heat stored in the hot water storage tank is controlled. When the amount of heat generated exceeds a predetermined amount of heat, the heat exhaust operation is executed.

According to this characteristic configuration, the fuel cell exhaust heat utilization system performs cool air operation if the amount of heat stored in the hot water storage tank is less than a predetermined amount of heat when executing the low temperature drying mode using the bathroom heater/dryer. However, when the amount of heat stored in the hot water storage tank exceeds a predetermined amount of heat while the cool air operation is being performed, the exhaust heat operation is performed. Therefore, the exhaust heat of the fuel cell can be used to operate in the low temperature drying mode without using an auxiliary heat source device. As a result, the exhaust heat of the fuel cell can be effectively utilized in the exhaust heat utilization system.

In a further characteristic configuration of the fuel cell exhaust heat utilization system according to the present invention, in the low temperature drying mode , during the execution of the exhaust heat operation, the amount of heat stored in the hot water storage tank is less than a predetermined amount of heat. If the amount of heat stored in the hot water storage tank exceeds a predetermined amount of heat during execution of the cooling air operation, the exhaust heat operation is performed instead of the cooling air operation. The point is to carry out.

According to this characteristic configuration, even after shifting to cool air operation due to the amount of heat stored in the hot water storage tank becoming less than a predetermined amount of heat during execution of exhaust heat operation, the amount of heat stored in the hot water storage tank will be reduced to a predetermined amount. When the amount of heat exceeds the amount of heat, exhaust heat operation can be performed again. Thereby, the exhaust heat utilization system can effectively utilize the exhaust heat of the fuel cell when executing the low temperature drying mode of the bathroom heater/dryer.

The characteristic configuration of the fuel cell system according to the present invention is as follows:
A fuel cell system connected to a bathroom heater/dryer,
A fuel cell that generates waste heat,
a hot water storage tank that stores waste heat from the fuel cell as hot water;
a hot water circulation flow path through which hot water in the hot water storage tank circulates;
A first heat exchanger that performs heat exchange between the hot water flowing through the hot water circulation flow path and the hot water flowing through the heating hot water circulation flow path in which hot water circulates through the bathroom heater/dryer that can utilize the heat of the hot water in the hot water storage tank. exchanger and
an auxiliary heat source device that heats the hot water flowing through the stored hot water circulation flow path;
a control unit that controls the flow of hot water in the stored hot water circulation flow path and the heating hot water circulation flow path, the operation of the bathroom heating dryer, and the operation of the auxiliary heat source device ,
The bathroom heating dryer includes a second heat exchanger that exchanges heat with the hot water circulating in the heating hot water circulation flow path, and sucks air that can be heated by the second heat exchanger and circulates it in the bathroom. and a circulation fan, and is capable of executing a low temperature drying mode and a high temperature drying mode in which the circulation fan is driven to discharge heated air or unheated air into the bathroom,
The control unit includes:
When executing the low-temperature drying mode, if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the auxiliary heat source device is not used and hot water is circulated in the stored hot water circulation flow path and the heating hot water circulation flow path. If the amount of heat stored in the hot water storage tank is less than a predetermined amount of heat, executing a cool air operation that stops the circulation of hot water in the heating hot water circulation flow path ;
When executing the high temperature drying mode, if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the exhaust heat operation is executed, and if the amount of heat stored in the hot water storage tank is less than the predetermined amount of heat, the The point is to execute an auxiliary heat source operation in which the auxiliary heat source device is driven to supply hot water heated by the auxiliary heat source device to the stored hot water circulation flow path .

According to this characteristic configuration, when the fuel cell system executes the low temperature drying mode, if the amount of heat stored in the hot water storage tank is equal to or higher than the predetermined amount of heat, the fuel cell system executes the exhaust heat operation, and the amount of heat stored in the hot water storage tank is reduced. If the amount of heat is less than the predetermined amount, cool air operation is performed. Therefore, the exhaust heat of the fuel cell can be used to operate in the low temperature drying mode without using an auxiliary heat source device. As a result, the exhaust heat of the fuel cell can be effectively utilized in the fuel cell system. In addition, when executing the high temperature drying mode, the fuel cell system executes exhaust heat operation if the amount of heat stored in the hot water storage tank is equal to or greater than a predetermined amount of heat, and if the amount of heat stored in the hot water storage tank is less than the predetermined amount of heat. Then, an auxiliary heat source operation is executed in which the auxiliary heat source device is driven to supply hot water heated by the auxiliary heat source device to the stored hot water circulation flow path.
When drying a bathroom using a bathroom heater/dryer, when exhaust heat operation and cool air operation are used together, heated air is not supplied to the bathroom during the cool air operation. Therefore, the longer the cool air operation takes, the longer it takes to complete the bathroom drying. Therefore. This characteristic configuration is configured to allow execution of auxiliary heat source operation using an auxiliary heat source device. Thereby, by executing the auxiliary heat source operation in place of the cool air operation as needed, bathroom drying can be completed quickly.

In this manner, the fuel cell system with this configuration can directly use the exhaust heat of the fuel cell for the bathroom heater/dryer. For example, in polymer electrolyte fuel cells used as fuel cells, the operating temperature of the fuel cell reaction is low, and even if the waste heat is used, water can only be heated to about 40 degrees Celsius. It can be applied and used effectively. Therefore, even when a polymer electrolyte fuel cell is used as the fuel cell, the energy utilization rate can be increased by using the bathroom heater/dryer.

FIG. 1 is a system diagram schematically showing an exhaust heat utilization system according to an embodiment. It is a figure which shows the flowchart of the low temperature drying mode of a bathroom heating dryer. It is a figure which shows the flowchart of the high temperature drying mode of a bathroom heating dryer. It is a figure which shows the flowchart of the modification of the high temperature drying mode of a bathroom heating dryer.

Hereinafter, a fuel cell exhaust heat utilization system and a fuel cell system according to the present invention will be described with reference to the drawings.

In FIG. 1, a fuel cell exhaust heat utilization system 100 and a fuel cell system include a fuel cell (for example, a polymer electrolyte fuel cell) 2 and a hot water storage tank 4 for storing hot water. , is equipped with an auxiliary heat source device 6 for heating water (or hot water) using an auxiliary heat source. The fuel cell 2 uses heat generated by the fuel cell reaction to heat the water flowing through the heat recovery low-temperature pipe 24, and the auxiliary heat source device 6 heats the water in the stored hot water circulation channel 12 by combustion operation. Water flowing through the heating hot water circulation flow path 31 is heated by the heating heat exchanger 13. Hot water heated by the exhaust heat of the fuel cell 2 is stored in a hot water storage tank 4. Further, in this embodiment, the exhaust heat of the fuel cell 2 and/or the combustion heat of the auxiliary heat source device 6 is configured to be consumed by the bathroom heater/dryer 8 as a heat consuming device.

An exhaust heat recovery unit 20 is provided near the fuel cell 2 to collect water taken out from the lower part of the hot water storage tank 4 and return it to the upper part of the hot water storage tank 4 after recovering the exhaust heat of the fuel cell 2 and raising the temperature of the water. There is.

The exhaust heat recovery unit 20 includes an exhaust heat recovery heat exchanger 21 for recovering exhaust heat of the fuel cell 2, and an exhaust heat recovery circulation pump 22. The inlet side of the exhaust heat recovery unit 20 and the lower water intake port 14 of the hot water storage tank 4 are connected by a heat recovery cryogenic pipe 24, and the outlet side of the exhaust heat recovery unit 20 and the upper return port 15 of the hot water storage tank 4 are connected. are connected by a heat recovery high temperature pipe 25. The heat recovery low-temperature pipe 24 and the heat recovery high-temperature pipe 25 are configured as a circulation path. Furthermore, the water flowing through the heat recovery low-temperature pipe 24 and the heat recovery high-temperature pipe 25 functions as cooling water for the fuel cell 2 .

A hot water circulation channel 12 is connected to the hot water storage tank 4 . In the stored hot water circulation flow path 12, an auxiliary heat source device 6, a heating heat exchanger 13 (an example of a first heat exchanger), an on-off valve 16, and a circulation pump 17 are arranged. The auxiliary heat source device 6 heats water in the hot water storage tank 4 or water in a water supply channel (not shown) and supplies the heated water to the heating heat exchanger 13 via the hot water circulation channel 12 . The heating heat exchanger 13 is used to transfer the heat of the hot water in the hot water storage tank 4 or the hot water heated by the auxiliary heat source device 6 to the water flowing through the heating hot water circulation flow path 31. Hot water in the hot water circulation channel 12 is supplied to the heating heat exchanger 13 by a circulation pump 17 . The hot water storage tank 4 has a thermistor (not shown), and the temperature of the hot water in the hot water storage tank 4 detected by the thermistor is output from the thermistor to the control unit 60.

The heat of the hot water flowing through the stored hot water circulation channel 12 is configured to be consumed in the bathroom heater/dryer 8. The bathroom heater/dryer 8 accommodates a part of the heating hot water circulation flow path 31, a heat exchanger 32 (an example of a second heat exchanger), and a circulation fan 33. A heat exchanger 32 (an example of a second heat exchanger), a thermal valve 34, and a circulation pump 35 are arranged in the heating hot water circulation flow path 31. The heating hot water circulation flow path 31 is used to supply hot water heated by the heating heat exchanger 13 to the heat exchanger 32. In the heating heat exchanger 13, heat exchange is performed between the hot water flowing through the stored hot water circulation passage 12 and the water flowing through the heating hot water circulation passage 31. Through this heat exchange, the water in the heating hot water circulation flow path 31 is heated, and the air inside the bathroom heating/drying device 8 can be heated by the heat exchanger 32 disposed in the bathroom heating/drying device 8 . The circulation fan 33 is for sucking air that can be heated by the heat exchanger 32 from inside the bathroom and circulating it into the bathroom. The air heated by the heat exchanger 32 can be circulated within the bathroom by driving the circulation fan 33. The thermal valve 34 is a valve that is opened and closed using a thermal element (pellet), and allows circulation of water in the heating hot water circulation flow path 31 when opened. The opening and closing operations of the thermal valve 34 are controlled by a control section 60.

The exhaust heat utilization system 100 controls the fuel cell 2, the hot water storage tank 4, the bathroom heating dryer 8, the stored hot water circulation flow path 12, the heating hot water circulation flow path 31, the heating heat exchanger 13, and the system. The control unit 60 is configured to include a control unit 60 for The fuel cell system includes a fuel cell 2, a hot water storage tank 4, a stored hot water circulation flow path 12, a heating heat exchanger 13, and a control unit 60.

In this embodiment, the control unit 60 is configured to be able to execute a low temperature drying mode and a high temperature drying mode as the bathroom drying mode. The control unit 60 also controls the operation of the fuel cell 2, the auxiliary heat source device 6, and the bathroom heating/drying device 8, and the water in the exhaust heat recovery circulation pump 22, the stored hot water circulation path 12, and the heating hot water circulation path 31. Control the flow etc. The operation of the bathroom heater/dryer 8 is controlled by, for example, a dedicated remote controller (not shown).

The low-temperature drying mode is an operation mode in which bathroom drying is performed using a combination of exhaust heat operation that utilizes the exhaust heat of the fuel cell 2 and cool air operation that does not utilize either the exhaust heat of the fuel cell 2 or the auxiliary heat source device 6. . On the other hand, the high-temperature drying mode is an operation mode in which bathroom drying is performed using a combination of exhaust heat operation using the exhaust heat of the fuel cell 2 and auxiliary heat source operation using the auxiliary heat source device 6. The operating states of the above-described exhaust heat utilization system 100 of the fuel cell 2 in various operating modes will be explained. When the low temperature drying mode is executed in the control unit 60, control based on the flowchart shown in FIG. 2 is performed.

[Low temperature drying mode]
In the low temperature drying mode, the bathroom heating dryer 8 is started in step #11. Specifically, the circulation fan 33 is driven. In step #12, it is determined whether the amount of heat in the hot water storage tank 4 is greater than or equal to a predetermined amount of heat (above a predetermined temperature and a predetermined amount of water). The temperature of the hot water in the hot water storage tank 4 is output to the control unit 60 from a thermistor (not shown) arranged in the hot water storage tank 4. Therefore, the control unit 60 is able to determine whether the amount of heat in the hot water storage tank 4 is greater than or equal to a predetermined amount of heat (above a predetermined temperature and a predetermined amount of water) based on the temperature and amount of hot water in the hot water storage tank 4. can. If it is determined that the amount of heat in the hot water storage tank 4 is greater than or equal to the predetermined amount of heat (step #12, YES), exhaust heat operation is executed in step #13. Specifically, while the on-off valve 16 is opened, the circulation pump 17 is operated to allow hot water to circulate in the stored hot water circulation channel 12, and the thermal valve 34 is opened and the circulation pump 35 is operated. Circulation of hot water in the heating hot water circulation flow path 31 is allowed. Thereby, in the heating heat exchanger 13 , the heat of the hot water in the hot water storage tank 4 is transferred to the water in the heating hot water circulation flow path 31 , and the air inside the bathroom heating/drying device 8 is heated by the heat exchanger 32 . As a result, the bathroom heater/dryer 8 can circulate the heated air into the bathroom by operating the circulation fan 33.

On the other hand, if it is determined that the amount of heat in the hot water storage tank 4 is less than the predetermined amount of heat (step #12, NO), cool air operation is performed in step #14. Specifically, while closing the on-off valve 16, the circulation pump 17 is stopped to stop the circulation of hot water in the stored hot water circulation channel 12, and at the same time, the circulation pump 35 is stopped while the thermal valve 34 is closed. The circulation of hot water in the heating hot water circulation flow path 31 is stopped. Thereby, the bathroom heater/dryer 8 can circulate unheated air (cool air) into the bathroom by operating the circulation fan 33.

During the heat exhaust operation, if the operation of the bathroom heater/dryer 8 is confirmed in step #15 and is not stopped (operating) (step #15, NO), the process returns to step #12 and the hot water storage tank 4 is It is checked again whether the amount of heat is greater than or equal to the predetermined amount of heat. During the heat exhaust operation, if the amount of heat in the hot water storage tank 4 becomes less than the predetermined amount of heat (step #12, NO), a cool air operation (step #14) is performed instead of the heat exhaust operation.

On the other hand, during the cool air operation, if the operation of the bathroom heater/dryer 8 is confirmed in step #15 and is not stopped (operating) (step #15, NO), the process returns to step #12 and the hot water storage tank 8 It is checked again whether or not the amount of heat within is greater than or equal to the predetermined amount of heat. During the cooling air operation, when the amount of heat in the hot water storage tank 4 reaches a predetermined amount of heat (step #12, YES), exhaust heat operation (step #13) is executed instead of the cooling air operation, and the amount of heat in the hot water storage tank 4 reaches the predetermined value. If it is less than the amount of heat (step #12, NO), the cool air operation is continued (step #14). During both the exhaust heat operation and the cool air operation, when it is confirmed in step #15 that the bathroom heater/dryer 8 has stopped (step #15, YES), the low temperature drying mode ends.

When the high temperature drying mode is set in the control unit 60, control based on the flowchart shown in FIG. 3 is performed.

[High temperature drying mode]
In the high temperature drying mode, the bathroom heating dryer 8 is started in step #21. Specifically, the circulation fan 33 is driven. In step #22, it is determined whether the amount of heat in the hot water storage tank 4 is greater than or equal to a predetermined amount of heat. If it is determined that the amount of heat in the hot water storage tank 4 is greater than or equal to the predetermined amount of heat (step #22, YES), exhaust heat operation is performed in step #23.

On the other hand, if it is determined that the amount of heat in the hot water storage tank 4 is less than the predetermined amount of heat (step #22, NO), the auxiliary heat source operation is performed in step #23. Specifically, the auxiliary heat source device 6 is driven, and the circulation pump 17 is operated while the on-off valve 16 is opened to supply hot water heated by the auxiliary heat source device 6 to the stored hot water circulation flow path 12 to allow circulation. At the same time, the circulation pump 35 is operated while the thermal valve 34 is opened to allow circulation of hot water in the heating hot water circulation channel 31. Thereby, in the heating heat exchanger 13 , the heat of the hot water in the hot water storage tank 4 is transferred to the water in the heating hot water circulation flow path 31 , and the air inside the bathroom heating/drying device 8 is heated by the heat exchanger 32 . As a result, the bathroom heater/dryer 8 can circulate the heated air into the bathroom by operating the circulation fan 33.

During the heat exhaust operation, if the operation of the bathroom heater/dryer 8 is confirmed in step #25 and is not stopped (operating) (step #25, NO), the process returns to step #22 and the hot water storage tank 4 is It is checked again whether the amount of heat is greater than or equal to the predetermined amount of heat. During the exhaust heat operation, when the amount of heat in the hot water storage tank 4 becomes less than the predetermined amount of heat (step #22, NO), the auxiliary heat source operation is performed in place of the exhaust heat operation (step #24). During the heat exhaust operation, when it is confirmed in step #25 that the bathroom heater/dryer 8 has stopped (step #25, YES), the high temperature drying mode ends.

During the auxiliary heat source operation, if the operation of the bathroom heater/dryer 8 is confirmed in step #26 and is not stopped (operating) (step #26, NO), the auxiliary heat source operation is continued. When it is confirmed in step #26 that the bathroom heater/dryer 8 has stopped (step #26, YES), the high temperature drying mode ends.

[Variation example of high temperature drying mode]
A modification of the high temperature drying mode will be explained based on the flowchart shown in FIG. 4.

In the flowchart shown in FIG. 3, the auxiliary heat source operation continues until the bathroom heater/dryer 8 is stopped. Instead, in the flowchart shown in FIG. 4, when the operation of the bathroom heater/dryer 8 is confirmed in step #25 and is not stopped (in operation) during the auxiliary heat source operation (step #25, NO). Returning to step #22, it is checked again whether the amount of heat in the hot water storage tank 4 is greater than or equal to the predetermined amount of heat. During the auxiliary heat source operation, when the amount of heat in the hot water storage tank 4 exceeds the predetermined amount of heat (step #22, YES), the exhaust heat operation (step #13) is executed instead of the auxiliary heat source operation. That is, the auxiliary heat source device 6 stops. During both the exhaust heat operation and the auxiliary heat source operation, when it is confirmed in step #25 that the bathroom heater/dryer 8 has stopped (step #15, YES), the high temperature drying mode ends.

Thereby, in the high temperature drying mode using the auxiliary heat source device 6, the exhaust heat of the fuel cell 2 can be used more effectively.

In the above embodiment, an example is shown in which a polymer electrolyte fuel cell is used as the fuel cell 2 of the exhaust heat utilization system 100 and the fuel cell system, but the fuel cell 2 is not limited to a polymer electrolyte fuel cell. As the fuel cell 2, other fuel cells such as a solid oxide fuel cell (SOFC) may be used.

In the above embodiment, an example was shown in which the exhaust heat utilization system 100 of the fuel cell 2 includes only the bathroom heater/dryer 8 as a heat consuming device, but a floor heating device may be added to the heat consuming device.

It should be noted that the configuration disclosed in the above embodiment (including other embodiments, the same applies hereinafter) can be applied in combination with the configuration disclosed in other embodiments as long as there is no contradiction, and The embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the purpose of the present invention.

The fuel cell exhaust heat utilization system and fuel cell system according to the present invention can be widely used in systems that use fuel cell exhaust heat for bathroom heater/dryers.

2: Fuel cell 4: Hot water storage tank 6: Auxiliary heat source device 8: Bathroom heater/dryer 12: Stored hot water circulation flow path 13: Heating heat exchanger (first heat exchanger)
14 : Lower water intake 15 : Upper return port 16 : Opening/closing valve 20 : Exhaust heat recovery unit 21 : Heat exchanger for exhaust heat recovery 22 : Circulation pump for exhaust heat recovery 24 : Heat recovery low temperature piping 25 : Heat recovery high temperature piping 31 : Heating hot water circulation flow path 32 : Heat exchanger (second heat exchanger)
33: Circulation fan 34: Thermal valve 60: Control unit 100: Exhaust heat utilization system

Claims (5)

A fuel cell that generates waste heat,
a hot water storage tank that stores waste heat from the fuel cell as hot water;
a bathroom heater/dryer capable of utilizing the heat of hot water in the hot water storage tank;
a hot water circulation flow path through which hot water in the hot water storage tank circulates;
a heating hot water circulation flow path through which hot water circulates through the bathroom heating dryer;
a first heat exchanger that exchanges heat between the hot water flowing through the stored hot water circulation flow path and the hot water flowing through the heating hot water circulation flow path;
an auxiliary heat source device that heats the hot water flowing through the stored hot water circulation flow path;
a control unit that controls the flow of hot water in the stored hot water circulation flow path and the heating hot water circulation flow path, the operation of the bathroom heating dryer, and the operation of the auxiliary heat source device ,
The bathroom heating dryer includes a second heat exchanger that exchanges heat with the hot water circulating in the heating hot water circulation flow path, and sucks air that can be heated by the second heat exchanger and circulates it in the bathroom. and a circulation fan, and is capable of executing a low temperature drying mode and a high temperature drying mode in which the circulation fan is driven to discharge heated air or unheated air into the bathroom,
The control unit includes:
When executing the low-temperature drying mode, if the amount of heat stored in the hot water storage tank is equal to or higher than a predetermined amount of heat, the auxiliary heat source device is not used and hot water is circulated in the stored hot water circulation flow path and the heating hot water circulation flow path. If the amount of heat stored in the hot water storage tank is less than a predetermined amount of heat, executing a cool air operation that stops the circulation of hot water in the heating hot water circulation flow path ;
When executing the high temperature drying mode, if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the exhaust heat operation is executed, and if the amount of heat stored in the hot water storage tank is less than the predetermined amount of heat, the A fuel cell exhaust heat utilization system that performs an auxiliary heat source operation in which an auxiliary heat source device is driven to supply hot water heated by the auxiliary heat source device to the stored hot water circulation flow path . When executing the low-temperature drying mode , if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the control unit executes the exhaust heat operation, and during the execution of the exhaust heat operation, the controller The exhaust heat utilization system for a fuel cell according to claim 1, wherein the cool air operation is executed when the stored amount of heat becomes less than a predetermined amount of heat. When executing the low-temperature drying mode , if the amount of heat stored in the hot water storage tank is less than a predetermined amount of heat, the control unit executes the cool air operation, and during the execution of the cool air operation, the amount of heat stored in the hot water storage tank is controlled. The exhaust heat utilization system for a fuel cell according to claim 1, wherein the exhaust heat operation is executed when the amount of heat generated exceeds a predetermined amount of heat. In the low-temperature drying mode , when the amount of heat stored in the hot water storage tank becomes less than a predetermined amount of heat during execution of the exhaust heat operation, the controller executes the cool air operation instead of the exhaust heat operation; The fuel according to any one of claims 1 to 3, wherein during execution of the cool air operation, when the amount of heat stored in the hot water storage tank exceeds a predetermined amount of heat, the exhaust heat operation is performed in place of the cool air operation. Battery waste heat utilization system. A fuel cell system connected to a bathroom heater/dryer,
A fuel cell that generates waste heat,
a hot water storage tank that stores waste heat from the fuel cell as hot water;
a hot water circulation flow path through which hot water in the hot water storage tank circulates;
A first heat exchanger that performs heat exchange between the hot water flowing through the hot water circulation flow path and the hot water flowing through the heating hot water circulation flow path in which hot water circulates through the bathroom heater/dryer that can utilize the heat of the hot water in the hot water storage tank. exchanger and
an auxiliary heat source device that heats the hot water flowing through the stored hot water circulation flow path;
a control unit that controls the flow of hot water in the stored hot water circulation flow path and the heating hot water circulation flow path, the operation of the bathroom heating dryer, and the operation of the auxiliary heat source device ,
The bathroom heating dryer includes a second heat exchanger that exchanges heat with the hot water circulating in the heating hot water circulation flow path, and sucks air that can be heated by the second heat exchanger and circulates it in the bathroom. and a circulation fan, and is capable of executing a low temperature drying mode and a high temperature drying mode in which the circulation fan is driven to discharge heated air or unheated air into the bathroom,
The control unit includes:
When executing the low-temperature drying mode, if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the auxiliary heat source device is not used and hot water is circulated in the stored hot water circulation flow path and the heating hot water circulation flow path. If the amount of heat stored in the hot water storage tank is less than a predetermined amount of heat, executing a cool air operation that stops the circulation of hot water in the heating hot water circulation flow path ;
When executing the high temperature drying mode, if the amount of heat stored in the hot water storage tank is greater than or equal to a predetermined amount of heat, the exhaust heat operation is executed, and if the amount of heat stored in the hot water storage tank is less than the predetermined amount of heat, the A fuel cell system that performs an auxiliary heat source operation in which an auxiliary heat source device is driven to supply hot water heated by the auxiliary heat source device to the stored hot water circulation flow path .

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