JP2016103363A - Fuel battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery system that can be supplied with water used for power generation from the outside and suppress reduction of the power generation amount.SOLUTION: A fuel battery system has a fuel battery 1, a heat exchange unit 2 for performing heat-exchange between exhaust gas discharged from the fuel battery and heat medium to reduce exhaust gas temperature and withdraw water, a storage tank 4 for storing the heat medium heated by the heat-exchange with the exhaust gas, a detector 41 for detecting the temperature state of the heat medium in the storage tank, a circulation flow path 8 for circulating the heat medium in the storage tank through the heat-exchange unit, a heat radiation unit 3 for making the heat medium flowing in the circulation flow path radiate heat, a heater 5 for heating the heat medium flowing in the circulation flow path, a calculator 6 for calculating heat radiation tolerance of the heat radiation unit, and an output controller 7 for controlling power generation output of the fuel battery. When the heat medium in the storage tank is determined to reach a full storage state, the output controller controls the power generation output of the fuel battery so that the power generation output is larger than the lowest power generation output within a range where the heat radiation tolerance has a positive value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system capable of recovering water necessary for power generation from exhaust gas discharged from a fuel cell.

  When generating electricity with a fuel cell, for example, water is required when steam reforming the raw material. Therefore, a fuel cell power generation device has been proposed that can recover the water required for such power generation from the exhaust gas discharged from the fuel cell (for example, Patent Document 1).

  The fuel cell power generator described in Patent Document 1 includes a condenser that condenses the oxidant gas discharged from the fuel cell, and the condensed water discharged from the condenser is humidified by at least one of the fuel gas and the oxidant gas. To use.

JP 2003-45471 A

  The present invention provides a fuel cell system that can be obtained without supplying water to be used for power generation from the outside and suppresses a decrease in the amount of power generation.

  In order to solve the above-described problem, an aspect of a fuel cell system according to the present invention performs heat exchange between a fuel cell, exhaust gas discharged from the fuel cell, and a heat medium, and A heat exchanging section for recovering water used for power generation of the fuel cell, a storage tank for storing the heat medium heated by heat exchange with the exhaust gas in the heat exchanging section, and the storage tank A detection unit that detects a temperature state of the heat medium in the storage tank, a circulation channel that circulates the heat medium in the storage tank through the heat exchange unit, and the heat medium that circulates in the circulation channel In the heat exchanging unit and the heater, a heat dissipating part, a heater that heats the heat medium flowing through the circulation channel, and a maximum heat dissipating amount that can be dissipated from the heat medium by the heat dissipating part. A calculation unit that calculates a heat dissipation margin of the heat dissipation unit, which is a value obtained by subtracting the amount of heat transferred to the medium, and an output control unit that controls a power generation output of the fuel cell, and the output When the control unit determines that the heat medium in the storage tank has reached the full storage state based on the detection result of the detection unit, the range in which the heat dissipation margin calculated by the calculation unit is a positive value. The power generation output of the fuel cell is controlled to be larger than a preset minimum power generation output that is a lower limit value of the power generation amount of the fuel cell.

  According to one embodiment of the present invention, water for use in power generation can be obtained without being supplied from the outside, and an effect that a decrease in power generation amount can be suppressed can be achieved.

It is a block diagram which shows an example of a structure of the fuel cell system which concerns on embodiment of this invention. It is a block diagram which shows an example of a structure of the fuel cell system which concerns on embodiment of this invention. It is a block diagram which shows an example of schematic structure regarding Example 1 of the fuel cell system shown in FIG. It is a block diagram which shows an example of schematic structure regarding Example 2 of the fuel cell system shown in FIG. It is a block diagram which shows an example of schematic structure regarding the modification of the fuel cell system of Example 2 shown in FIG.

(Background to obtaining one embodiment of the present invention)
The present inventors have earnestly studied a fuel cell system including a hot water storage tank that recovers heat from exhaust gas generated during power generation and stores water heated by the recovered heat. As a result, the following knowledge was obtained.

  First, the fuel cell is expected to be used as a distributed power source because it enables high power generation efficiency and secondary use of high-quality exhaust heat. In order to effectively function a distributed power generation system that uses a fuel cell as a distributed power source, it is necessary to stably supply raw materials during power generation. In general, the raw material of the fuel cell is supplied from an existing infrastructure, for example, natural gas (city gas) mainly composed of natural gas, LPG, gasoline, kerosene, or the like is used.

  By the way, a fuel cell generates electric power and heat simultaneously by causing an electrochemical reaction (power generation reaction) between a hydrogen-containing gas (reformed gas) and an oxidant gas such as air. Here, typical reforming methods for the supplied raw material include partial oxidation reforming in which reforming is performed in the presence of air and steam reforming in which reforming is performed in the presence of steam. Since the latter has higher power generation efficiency than the former, the latter has a longer operating time for consumption of the same amount of raw material, and fuel consumption can be saved. For this reason, when using a fuel cell as a distributed power supply, the structure which reforms a raw material by steam reforming is more advantageous.

  However, in order to function a distributed power generation system that generates reformed gas by steam reforming and uses a fuel cell as a distributed power source, in addition to the above-described raw materials, water is stably supplied to the distributed power generation system. It is necessary to supply. Here, the exhaust gas discharged from the fuel cell contains moisture. Accordingly, stable water supply can be achieved by collecting water used for power generation from the exhaust gas. In addition, it can be said that water can be recovered in the system without supplying water from an external water source and the water can be supplied.

  Here, the fuel cell having a hot water storage tank that stores the heat generated during power generation as hot water while the present inventors have configured to recover the water in the exhaust gas and stably supply the water as described above. After examining the operation of the system, I noticed the following problems.

  That is, when the hot water storage tank is fully stored and the hot water in the hot water storage tank cannot be discharged to the outside, the fuel cell does not exceed the upper limit heat storage amount of the hot water storage tank. In addition, it is necessary to reduce the power generation output and the amount of heat recovered from the exhaust gas. At this time, if the power generation output is lowered to a preset lower limit value, the power generation amount is reduced. For example, among the electric energy consumed at home and the like, the amount of power that can be provided by the power generation of the fuel cell is reduced, and the economic efficiency is reduced. There was a case of decline. Hereinafter, the lower limit value of the power generation output set in advance in the fuel cell is referred to as the minimum power generation output Q4.

  For example, the fuel cell power generation device of Patent Document 1 presented in the background art is configured to control the power generation output of the fuel cell based on the heat exchange capability of a condenser that performs condensation by heat exchange between exhaust gas and circulating water. ing. When the hot water storage tank is fully stored in such a configuration, water self-sustained in the fuel cell can be maintained, but it has been found that there is a case where it is not possible to prevent a reduction in the amount of power that can be covered by power generation, and the present invention has been achieved. . The present invention specifically provides the following modes.

  The fuel cell system according to the first aspect of the present invention is configured to exchange heat between a fuel cell and an exhaust gas discharged from the fuel cell and a heat medium, to reduce the temperature of the exhaust gas, and to generate electric power from the fuel cell. A heat exchanging unit that collects water used for the heat exchange, a storage tank that stores the heat medium heated by heat exchange with the exhaust gas in the heat exchanging unit, and a temperature state of the heat medium in the storage tank is detected A circulating flow path for circulating the heat medium in the storage tank through the heat exchange section, a heat dissipating section for dissipating the heat medium flowing through the circulation flow path, and a flow through the circulation flow path Subtracting the amount of heat transferred to the heat medium in the heat exchanging unit and the heater from the heater that heats the heat medium and the maximum heat radiation amount that can be dissipated from the heat medium by the heat dissipating unit. Asking A calculation unit that calculates a heat dissipation margin of the heat dissipation unit, and an output control unit that controls a power generation output of the fuel cell, and the output control unit is based on a detection result of the detection unit. When it is determined that the heat medium in the storage tank has reached a fully stored state, the heat dissipation margin calculated by the calculation unit is within a range in which the heat dissipation margin is a positive value. The power generation output of the fuel cell is controlled to be larger than the minimum power generation output that is the lower limit value of the power generation amount.

  According to the said structure, since the heat exchange part is provided, the water utilized for the electric power generation of a fuel cell can be collect | recovered from waste gas by the heat exchange between waste gas and a heat medium. That is, the water used for power generation can be recovered in the system without supplying water from an external water source.

  Moreover, since the heat radiating part, the heat exchanging part, and the heater are provided, the temperature of the heat medium flowing through the circulation channel can be adjusted. Furthermore, since the calculation unit is provided, the heat dissipation margin in the heat dissipation unit can be obtained. For this reason, when the heat medium in a storage tank reaches a full storage state, it can be grasped | ascertained whether it can radiate with a heat medium thermal radiation part, and the temperature of a heat medium can be reduced. In addition, since the output control unit is provided, the power generation output is larger than the minimum power generation output within a range where the heat dissipation margin is a positive value, that is, within a range where the heat medium can be radiated in the heat dissipation unit. In addition, the power generation output of the fuel cell can be controlled.

  Therefore, the fuel cell system according to the first aspect of the present invention can be covered by the power generation of the fuel cell as compared with the configuration in which the fuel cell generates power at the minimum power generation output when it is determined that the fully stored state has been reached. A decrease in the amount of power generation can be suppressed.

  Therefore, it is possible to obtain water for use in power generation without supplying it from the outside, and it is possible to suppress the decrease in power generation amount.

  In the fuel cell system according to a second aspect of the present invention, in the first aspect described above, the calculation unit calculates a heat exchange amount in the heat dissipation unit, thereby obtaining a maximum value of the heat dissipation amount of the heat medium. The first heat exchange amount calculation unit to be obtained, the second heat exchange amount calculation unit to obtain the amount of heat transferred from the exhaust gas to the heat medium by calculating the heat exchange amount in the heat exchange unit, and output by the heater From the maximum value of the amount of heat released from the heat medium obtained by the heater output detector that obtains the amount of heat transferred from the heater to the heat medium, and the first heat exchange amount calculator. A heat dissipation margin calculation unit that calculates the heat dissipation margin of the heat dissipation unit by subtracting the amount of heat transferred to the heat medium obtained by the second heat exchange amount calculation unit and the heater output detection unit. Configured as Good.

  In the fuel cell system according to the third aspect of the present invention, in the second aspect described above, the heat medium flow rate detection unit that detects the flow rate of the heat medium flowing through the circulation flow path, and the heat radiation unit flow A heat radiating unit inlet temperature sensor that measures a heat radiating unit inlet temperature that is a temperature of the heat medium; and a heat radiating unit outlet temperature sensor that measures a heat radiating unit outlet temperature that is a temperature of the heat medium flowing out of the heat radiating unit. The first heat exchange amount calculation unit includes a heat radiation unit inlet temperature measured by the heat radiation unit inlet temperature sensor, a heat radiation unit outlet temperature measured by the heat radiation unit outlet temperature sensor, and the heat medium flow rate detection unit. The heat exchange amount in the heat radiating section may be calculated from the flow rate of the heat medium flowing through the circulation flow path detected by the above.

  A fuel cell system according to a fourth aspect of the present invention is the fuel cell system according to the second aspect described above, wherein the heat medium flow rate detection unit detects the flow rate of the heat medium flowing through the circulation flow path, and flows into the heat exchange unit. A first heat exchange section inlet temperature sensor that measures a heat exchange section inlet temperature that is a temperature of the heat medium, and a first heat exchange section outlet temperature that is a temperature of the heat medium flowing out of the heat exchange section. A heat exchange unit outlet temperature sensor, wherein the second heat exchange amount calculation unit includes a heat exchange unit inlet temperature measured by the first heat exchange unit inlet temperature sensor and the first heat exchange unit outlet temperature. The amount of heat exchange in the heat exchange unit is calculated from the heat exchange unit outlet temperature measured by the sensor and the flow rate of the heat medium flowing through the circulation flow path detected by the heat medium flow rate detection unit. It may be configured.

  The fuel cell system according to a fifth aspect of the present invention is the fuel cell system according to the second aspect described above, wherein the exhaust gas flow path through which the exhaust gas discharged from the fuel cell flows, and the flow rate of the exhaust gas flowing through the exhaust gas flow path. An exhaust gas flow rate detection unit that detects the temperature, a second heat exchange unit inlet temperature sensor that measures the temperature of the heat exchange unit inlet that is the temperature of the exhaust gas flowing into the heat exchange unit, and the exhaust gas that flows out of the heat exchange unit A second heat exchange section outlet temperature sensor that measures a heat exchange section outlet temperature, which is a temperature, and the second heat exchange amount calculation section is configured to measure the heat measured by the second heat exchange section inlet temperature sensor. Such as the temperature at the inlet of the exchange, the temperature at the outlet of the heat exchanger measured by the outlet temperature sensor at the second heat exchanger, and the flow rate of the exhaust gas flowing through the circulation channel detected by the exhaust gas flow rate detector. It may be configured to calculate the amount of heat exchange in the heat exchange section.

  Hereinafter, specific examples of the embodiments will be described with reference to the drawings.

  In the following description, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and redundant description thereof may be omitted.

(Embodiment)
(Configuration of fuel cell system)
FIG. 1 is a block diagram showing an example of the configuration of a fuel cell system according to an embodiment of the present invention.

  As shown in FIG. 1, the fuel cell system includes a fuel cell 1, a heat exchange unit 2, a heat radiating unit 3, a storage tank 4, a detection unit 41, a circulation channel 8, a heater 5, and a calculation unit. 6 and an output control unit 7.

  The fuel cell 1 generates power by a reaction between fuel and air (power generation air), and examples thereof include a SOFC that can operate at high temperature. As the fuel, for example, a hydrogen-containing gas obtained by reforming a raw material such as natural gas (city gas) mainly containing natural gas can be used. The fuel cell 1 is configured such that the rated power generation output and the minimum power generation output Q4 are set in advance, and the power generation output can be switched in several steps with the minimum power generation output Q4 as a lower limit.

  The heat exchanging unit 2 exchanges heat between the exhaust gas discharged from the fuel cell 1 and the heat medium, lowers the temperature of the exhaust gas, and recovers water used for power generation of the fuel cell 1. That is, the heat exchanging unit 2 can recover the exhaust heat by the heat medium by heat exchange between the exhaust gas discharged from the fuel cell 1 and the heat medium. Further, the exhaust gas is recovered by the heat medium, so that the temperature of the exhaust gas is lowered. For this reason, the water contained in the exhaust gas can be condensed to obtain water. In addition, as the heat exchange part 2, although a plate type heat exchanger can be illustrated, for example, it is not limited to this. In the fuel cell system according to Embodiment 1, water can be exemplified as the heat medium. The water used for power generation can be, for example, reformed water for use in the steam reforming reaction when the fuel cell 1 is configured to reform the raw material by the steam reforming reaction. Although not shown in particular, the heat exchanging unit 2 may be configured to be connected to a condensed water tank that stores water obtained from the exhaust gas through a pipe.

  The storage tank 4 stores the heat medium heated by heat exchange with the exhaust gas in the heat exchange unit 2. In the fuel cell system according to Embodiment 1, when the heat medium is water, the storage tank 4 can be exemplified by a hot water storage tank. As shown in FIG. 1, a circulation channel 8 is connected to the storage tank 4, and the heat medium in the storage tank 4 flows through the circulation channel 8 and is heated by the heat exchange unit 2 and the heater 5. It is configured to come back. Further, when the storage tank 4 is a hot water storage tank, although not particularly illustrated, the hot water storage tank supplies, for example, a water supply channel for supplying city water and hot water stored in the hot water storage tank into the facility. The hot water supply flow path may be provided. When hot water in the hot water storage tank is consumed through the hot water supply channel, water is supplied through the water supply channel so as to cover the consumed amount. The storage tank 4 is provided with a detection unit 41.

  The detection unit 41 detects the temperature state of the heat medium in the storage tank 4. The detection unit 41 detects the amount of the heat medium that becomes a predetermined temperature or higher in the storage tank 4. Here, the predetermined temperature is a temperature set when the heat medium heated by the heat exchange unit 2 and the heater 5 is stored in the storage tank 4. The detection unit 41 can be realized by, for example, a plurality of temperature sensors that are provided at predetermined intervals in the vertical direction in the cylindrical storage tank 4 and measure the temperature of the heat medium stored in the storage tank 4. The detection unit 41 transmits the detection result to the main control unit.

  In addition, when the detection unit 41 detects that the temperature of the heat medium has become equal to or higher than the predetermined temperature at all positions in the storage tank 4, no further heat storage operation is possible in the fuel cell system. In the fuel cell system, when the heat storage operation becomes impossible in this way, the main control unit determines that the storage tank 4 is fully stored.

  The circulation channel 8 is a channel for circulating the heat medium in the storage tank 4 through the heat exchange unit 2. The circulation flow path 8 is constituted by, for example, equipment provided in the circulation flow path 8 and piping or a hose connecting these equipment.

  The heat radiating section 3 radiates heat from the heat medium flowing through the circulation channel 8. The heat radiating unit 3 can be composed of, for example, a heat exchanger that exchanges heat between the heat medium and air and a fan that supplies air to the heat exchanger. For example, the main control unit adjusts the amount of air moved per unit time by controlling the number of rotations of the fan, or adjusts the flow rate per unit time of the heat medium flowing through the circulation flow path 8. The heat radiation amount of the heat medium by the heat radiation part 3 can be controlled.

  In addition, when the thermal radiation part 3 is comprised from a heat exchanger and a fan, although a plate fin type heat exchanger can mainly be used for a heat exchanger, it is not limited to this. Moreover, the fan should just be what can thermally radiate a heat medium by supplying air to a heat exchanger from the outside and making it heat-exchange between this air and a heat medium. For example, an axial fan can be used as the fan, but the fan is not limited to this.

  The heater 5 heats the heat medium flowing through the circulation flow path 8. In the fuel cell system according to the present embodiment, the power generation output of the fuel cell 1 may increase with respect to the power load during operation. In such a case, the electric power obtained by the power generation of the fuel cell 1 is left. Therefore, the heater 5 is operated using the surplus power. Further, the heater 5 may be connected to another power supply source other than the fuel cell 1. Thus, in the case of the configuration connected to another power supply source, it is advantageous in that the heater 5 can be operated as needed even when there is no surplus power. As the heater 5, a heater integrated with a pipe constituting a part of the circulation flow path 8 is mainly used, but the heater 5 is not limited to this.

  The calculation unit 6 is a value obtained by subtracting the amount of heat transferred to the heat medium by the heat exchange unit 2 and the heater 5 from the maximum heat radiation amount that can be radiated from the heat medium by the heat radiating unit 3. The heat dissipation margin of part 3 is calculated. Here, the heat dissipation amount of the heat medium varies due to the heat amount of the heat medium and the flow rate of the heat medium flowing through the circulation flow path 8. For this reason, the maximum heat radiation amount is the discharge required when the heat medium for calculating the heat radiation margin is circulated through the circulation flow path 8 at the maximum flow rate and the heat radiation capability of the heat radiation part 3 is maximized. It is a value of the amount of heat (heat exchange amount).

  The output control unit 7 controls the power generation output of the fuel cell 1. More specifically, when the output control unit 7 determines that the heat medium in the storage tank 4 has reached the full storage state based on the detection result of the detection unit 41, the heat dissipation margin calculated by the calculation unit 6 is correct. The power generation output of the fuel cell 1 is controlled so as to be larger than the minimum power generation output that is a lower limit value of the power generation amount of the fuel cell 1 set in advance. The output control unit 7 can control the power generation output of the fuel cell 1 by adjusting the flow rates of a fuel supply pump that supplies fuel to the fuel cell 1 and an air blower that supplies power generation air, for example.

  The calculation unit 6 and the output control unit 7 can be realized, for example, by executing a program read from a memory (not shown) by the main control unit. The main control unit controls various operations of each unit included in the fuel cell system, and includes a calculation processing unit and a memory (not shown). The arithmetic processing unit is exemplified by an MPU or CPU, and the memory is exemplified by a nonvolatile memory, but is not limited thereto. Further, in the fuel cell system according to the present embodiment, the calculation unit 6 and the output control unit 7 are realized by one main control unit, but each may be realized by a separate control unit. .

  Here, with reference to FIG. 2, the structure of the calculation part 6 is demonstrated in detail. FIG. 2 is a block diagram showing an example of the configuration of the fuel cell system according to the embodiment of the present invention. As shown in FIG. 2, the calculation unit 6 includes a first heat exchange amount calculation unit 61, a second heat exchange amount calculation unit 62, a heater output detection unit 63, and a heat dissipation margin calculation unit 64.

  The first heat exchange amount calculation unit 61 calculates the heat exchange amount in the heat radiating unit 3 to obtain the maximum value of the heat dissipation amount of the heat medium. That is, when it is determined that the inside of the storage tank 4 has reached the full storage state, the heat exchange amount in the heat radiating unit 3 when the heat medium at that time is circulated through the circulation flow path 8 at the maximum flow rate is the first heat. The exchange amount calculation unit 61 calculates and obtains a maximum heat release amount (maximum heat exchange amount) Q2 which is the maximum value of the heat release amount of the heat medium.

  The second heat exchange amount calculation unit 62 calculates the heat exchange amount in the heat exchange unit 2, thereby obtaining the amount of heat (heat exchange amount Q1) transferred from the exhaust gas to the heat medium in the heat exchange unit 2.

  The heater output detection unit 63 obtains the amount of heat transferred from the heater 5 to the heat medium by detecting the amount of heat output from the heater 5. For example, the heater output detection unit 63 obtains surplus power from the difference between the power load and the output of the fuel cell 1, and obtains the amount of heat (heat transfer amount Q3) transferred from the power to the heat medium by the heater 5. Also good.

  The heat dissipation margin calculation unit 64 calculates heat from the maximum heat dissipation amount Q2 of the heat dissipation unit 3 determined by the first heat exchange amount calculation unit 61 and the heat dissipation amount calculated by the second heat exchange amount calculation unit 62 and the heater output detection unit 63. The heat dissipation margin of the heat radiating part 3 is calculated by subtracting the amount of heat (Q1 + Q3) transferred to the medium. The heat dissipation margin calculation unit 64 outputs the calculated result to the output control unit 7.

(Fuel cell output control)
Next, output control of the fuel cell 1 in the fuel cell system will be described with reference to FIG. 2 described above. More specifically, output control of the fuel cell 1 when it is determined that the storage tank 4 has become fully stored will be described.

  First, the output control unit 7 of the main control unit determines whether or not the inside of the storage tank 4 has reached the full storage state based on the detection result by the detection unit 41. If it is determined at time t0 that the output control unit 7 has reached the full storage state, the calculation unit 6 is instructed to calculate the heat dissipation margin. In response to the instruction from the output control unit 7, the calculation unit 6 determines the maximum heat radiation amount (maximum) by the heat radiation unit 3 at the time point (time t0) when the first heat exchange amount calculation unit 61 determines that the full storage state has been reached. Heat exchange amount) Q2 is calculated. That is, the first heat exchange amount calculation unit 61 calculates the maximum heat dissipation amount Q2 from the heat medium input / output temperature in the heat dissipation unit 3 and the maximum value of the flow rate of the heat medium flowing through the circulation flow path 8 at time t0. calculate. Further, the second heat exchange amount calculation unit 62 calculates the heat exchange amount Q1 between the exhaust gas and the heat medium in the heat exchange unit 2. Further, the heater output detection unit 63 calculates a heat transfer amount Q3 indicating the amount of heat output by the heater 5. In the calculation unit 6, the heat dissipation margin calculation unit 64 subtracts the heat exchange amount Q1 and the heat transfer amount Q3 calculated from the calculated maximum heat dissipation amount Q2 to calculate the heat dissipation margin of the heat dissipation unit 3.

  Here, when the heat dissipation margin calculated by the calculation unit 6 is 0 or more (when Q2−Q1−Q3 ≧ 0), the output control unit 7 determines that the heat dissipation margin is greater than the minimum power generation output Q4 at the next time t1. The fuel cell 1 is controlled so as to output at a power generation amount (Q4 + Q2-Q1-Q3) in which the power generation output is increased by the degree. Note that t0 is the time when it is determined that the fully stored state has been reached. On the other hand, t1 is the time when the fuel cell 1 outputs the power generation output according to the instruction from the output control unit 7, and t1 is because the fuel cell 1 responds to the control instruction from the output control unit 7 at t0. Is the time obtained by adding the necessary time Δt.

When it is determined that the fully stored state has been reached, the fuel cell 1 is stopped or power generation is continued at the preset minimum power output Q4. When the fuel cell 1 is an SOFC, it cannot be selected to stop the fuel cell 1 because it takes a long time to restart or the stack is damaged, and thus power is generated at the minimum power output Q4. Further, the case where the heat dissipation margin is 0 or more means that there is a surplus capacity to further dissipate the heat medium in the heat dissipating unit 3, and when it is determined that the fully stored state is reached (t0), the fuel cell 1 Can generate power with a larger power generation output than when generating power with the lowest power generation output Q4. In the fuel cell system according to the present embodiment, as described above, the fuel cell 1 is configured to increase the power generation output by the amount of the heat dissipation margin from the minimum power generation output Q4 as described above, but is not limited thereto. Absent. The fuel cell 1 should just be comprised so that it may become a power generation output larger than the minimum power generation output Q4 in the range from which the heat radiation margin becomes a positive value at least.

  As described above, when the heat dissipation margin is 0 or more (when Q2-Q1-Q3 ≧ 0), the power generation output of the fuel cell 1 can be made higher than the preset minimum power generation output Q4. For this reason, compared with the structure in which the fuel cell 1 generates power with the minimum power generation output Q4 when it is determined that the full storage state has been reached, it is possible to suppress a decrease in the amount of power generated by the power generation of the fuel cell 1. .

  On the other hand, when the heat dissipation margin calculated by the calculation unit 6 is less than 0 (when Q2-Q1-Q3 <0), the output control unit 7 outputs the fuel cell so as to output at the minimum power generation output Q4 at time t1. 1 is controlled.

Example 1
Next, Example 1 of the fuel cell system according to the present embodiment will be described with reference to FIG. In the first embodiment, an example of a method for calculating the heat exchange amount in the heat radiating unit 3 by the first heat exchange amount calculating unit 61 will be described. FIG. 3 is a block diagram showing an example of a schematic configuration related to Example 1 of the fuel cell system shown in FIG.

  As shown in FIG. 3, the fuel cell system according to Example 1 includes, in the configuration of the fuel cell system according to the embodiment shown in FIG. 2, a heat medium flow rate detection unit 9, a heat radiation unit inlet temperature sensor 33, and The difference is that it includes a heat radiating section outlet temperature sensor 34. Since it becomes the same about other points, the same code | symbol is attached | subjected to the same member and description about these members is abbreviate | omitted.

  The heat medium flow rate detection unit 9 detects the flow rate of the heat medium flowing through the circulation flow path 8. For example, although not particularly illustrated, the circulation channel 8 is provided with a circulation pump for circulating the heat medium stored in the storage tank 4. Therefore, the heat medium flow rate detection unit 9 is configured to detect the flow rate per unit time of the heat medium flowing through the circulation flow path 8 from the input current and voltage to the circulation pump and the operation amount of the circulation pump. Also good. Alternatively, the heat medium flow rate detection unit 9 may be a flow rate measurement device that is directly provided in the circulation flow path 8 and measures the flow rate per unit time of the heat medium flowing through the circulation flow path 8. In addition, when the heat medium which distribute | circulates the circulation flow path 8 is water, the above-mentioned circulation pump can mainly use water pumps, such as a blanker type and a magnet type.

  The heat radiating portion inlet temperature sensor 33 measures the heat radiating portion inlet temperature, which is the temperature of the heat medium flowing into the heat radiating portion 3. For example, the heat radiating portion inlet temperature sensor 33 can be installed in a pipe or a joint connecting the storage tank 4 and the heat radiating portion 3 in the circulation flow path 8 or in a flow channel on the inlet side of the heat radiating portion 3. The heat radiation part inlet temperature sensor 33 can mainly use a thermistor, but is not limited to this.

  On the other hand, the heat radiating portion outlet temperature sensor 34 measures the heat radiating portion outlet temperature, which is the temperature of the heat medium flowing out from the heat radiating portion 3. For example, the heat radiating portion outlet temperature sensor 34 can be installed in a pipe or a joint connecting the heat radiating portion 3 and the heat exchanging portion 2 in the circulation flow path 8 or in a flow passage on the outlet side of the heat radiating portion 3. Although the thermistor can mainly be used for the heat radiating portion outlet temperature sensor 34, it is not limited to this.

In the configuration described above, the first heat exchange amount calculation unit 61 can obtain the heat exchange amount in the heat radiating unit 3 using the following equations (1) and (2).
Q = H2-H1 (1)
Here, Q is the heat exchange amount [W] in the heat radiating section 3, H1 is the heat radiating section inlet enthalpy [W] of the heat medium, and H2 is the heat radiating section outlet enthalpy [W]. In addition, each enthalpy H [W] can be calculated | required from the relationship shown in the following formula | equation (2).
H ∝ m × F (2)
(F: n-order function of temperature of heat medium, m: flow rate of heat medium [mol / s])
That is, using the detection results of the heat radiation part inlet temperature sensor 33 and the heat radiation part outlet temperature sensor 34, the heat radiation part inlet enthalpy [W] and the heat radiation part outlet enthalpy [W] are obtained by the equation (2). And the heat exchange amount in the thermal radiation part 3 can be calculated | required by Formula (1) using the value of these calculated | required enthalpies.

  In the fuel cell system according to the present embodiment, the maximum heat dissipation amount Q2 of the heat medium in the heat dissipation portion 3 is obtained. For this reason, the flow rate of the heat medium detected by the heat medium flow rate detection unit 9 is the maximum value of the flow rate of the heat medium flowing through the circulation flow path 8.

(Example 2)
Next, Example 2 of the fuel cell system according to the present embodiment will be described with reference to FIG. In the second embodiment, an example of a calculation method of the heat exchange amount in the heat exchange unit 2 by the second heat exchange amount calculation unit 62 will be described. FIG. 4 is a block diagram showing an example of a schematic configuration related to Example 2 of the fuel cell system shown in FIG.

  As shown in FIG. 4, the fuel cell system according to Example 2 further includes a heat medium flow rate detection unit 9 and a first heat exchange unit inlet temperature in the configuration of the fuel cell system according to the embodiment shown in FIG. 2. The sensor 21 and the 1st heat exchange part exit temperature sensor 22 are provided. Since it becomes the same about other points, the same code | symbol is attached | subjected to the same member and description about these members is abbreviate | omitted. The heat medium flow rate detection unit 9 is the same as the heat medium flow rate detection unit 9 included in the fuel cell system according to the first embodiment, and thus the description thereof is omitted.

  The first heat exchange unit inlet temperature sensor 21 measures the heat exchange unit inlet temperature, which is the temperature of the heat medium flowing into the heat exchange unit 2. For example, the first heat exchange unit inlet temperature sensor 21 is installed in a pipe or a joint connecting the heat radiating unit 3 and the heat exchange unit 2 in the circulation channel 8 or in a channel on the inlet side of the heat exchange unit 2. be able to. Although the thermistor can mainly be used for the 1st heat exchange part entrance temperature sensor 21, it is not limited to this.

  On the other hand, the first heat exchange unit outlet temperature sensor 22 measures the heat exchange unit outlet temperature, which is the temperature of the heat medium flowing out from the heat exchange unit 2. For example, the first heat exchange unit outlet temperature sensor 22 is installed in a pipe or a joint connecting the heat exchange unit 2 and the heater 5 in the circulation channel 8 or in a channel on the outlet side of the heat exchange unit 2. Can do. Although the thermistor can mainly be used for the 1st heat exchange part exit | outlet temperature sensor 22, it is not limited to this.

  In the configuration described above, the second heat exchange amount calculation unit 62 can obtain the heat exchange amount in the heat exchange unit 2 using the above-described equations (1) and (2). However, in Formula (1), Q is the heat exchange amount [W] in the heat exchange section 2, H1 is the heat exchange section entrance enthalpy [W] of the heat medium, and H2 is the heat exchange section exit enthalpy [W] of the heat medium. It becomes. In Equation (2), F is an n-order function of the temperature of the heat medium, and m is the flow rate [mol / s] of the heat medium.

  As described above, the second heat exchange amount calculation unit 62 uses the above equations (1) and (2), so that the temperature measured by the first heat exchange unit inlet temperature sensor 21 and the first heat exchange unit outlet From the temperature measured by the temperature sensor 22 and the flow rate of the heat medium detected by the heat medium flow rate detection unit 9, the heat exchange amount Q1 between the exhaust gas and the heat medium in the heat exchange unit 2 can be calculated.

  In addition, the structure which calculates the heat exchange amount in the heat exchange part 2 is not limited to the structure of Example 2 mentioned above. Hereinafter, another configuration for calculating the heat exchange amount in the heat exchange unit 2 will be described as a modification of the second embodiment.

(Modification of Example 2)
A modification of the second embodiment will be described with reference to FIG. FIG. 5 is a block diagram showing an example of a schematic configuration related to a modification of the fuel cell system of the embodiment 2 shown in FIG.

  As shown in FIG. 5, the fuel cell system according to the modification of the second embodiment differs from the configuration of the fuel cell system according to the second embodiment shown in FIG. 4 in the following points. That is, the fuel cell system according to the modification of the second embodiment further includes an exhaust gas flow rate detection unit 11 that detects the flow rate of the exhaust gas flowing through the exhaust gas flow path 10, and includes the first heat exchange unit inlet temperature sensor 21 and the first heat. Instead of the exchange unit outlet temperature sensor 22, a second heat exchange unit inlet temperature sensor 23 and a second heat exchange unit outlet temperature sensor 24 are provided. Except for this, the fuel cell system according to the modification of the second embodiment has the same configuration as that of the fuel cell system of the second embodiment. Therefore, the same members are denoted by the same reference numerals, and description thereof is omitted.

  The exhaust gas flow rate detection unit 11 is provided, for example, between the heat exchange unit 2 and the exhaust port (not shown) in the exhaust gas channel 10 and measures the flow rate per unit time of the exhaust gas flowing through the exhaust gas channel 10. It may be a flow rate measuring device. Alternatively, the main control unit holds in advance a table showing the correspondence relationship between the fuel usage rate, the air usage rate, and the exhaust gas flow rate of the fuel cell 1 in a memory (not shown), and the exhaust gas flow rate detection unit 11 Referring to FIG. 6, the exhaust gas flow rate may be estimated from the fuel utilization rate and air utilization rate of the fuel cell 1.

  The second heat exchange unit inlet temperature sensor 23 measures the heat exchange unit inlet temperature, which is the temperature of the exhaust gas flowing into the heat exchange unit 2. For example, the second heat exchange unit inlet temperature sensor 23 is a flow in the exhaust gas flow path 10 through which exhaust gas flows, in a pipe or a joint connecting the fuel cell 1 and the heat exchange unit 2, or on the inlet side of the heat exchange unit 2. Can be installed in the road. Although the thermistor can mainly be used for the 2nd heat exchange part entrance temperature sensor 23, it is not limited to this.

  On the other hand, the second heat exchange unit outlet temperature sensor 24 measures the heat exchange unit outlet temperature, which is the temperature of the exhaust gas flowing out from the heat exchange unit 2. For example, the first heat exchange unit outlet temperature sensor 22 is provided in the exhaust gas passage 10 in a pipe or joint between the heat exchange unit 2 and an exhaust port (not shown) through which exhaust gas is exhausted, or in the heat exchange unit 2. It can be installed in the flow path on the outlet side. Although the thermistor can mainly be used for the 1st heat exchange part exit | outlet temperature sensor 22, it is not limited to this.

  In the configuration described above, the second heat exchange amount calculation unit 62 can obtain the heat exchange amount in the heat exchange unit 2 using the above-described equations (1) and (2). However, in Formula (1), Q is the heat exchange amount [W] in the heat exchange unit 2, H1 is the heat exchange unit inlet enthalpy [W] of exhaust gas, and H2 is the heat exchange unit outlet enthalpy [W] of exhaust gas. . In equation (2), F is an n-order function of the temperature of the exhaust gas, and m is the flow rate [mol / s] of the exhaust gas.

  As described above, the second heat exchange amount calculation unit 62 uses the above formulas (1) and (2), and the temperature measured by the second heat exchange unit inlet temperature sensor 23 and the second heat exchange unit outlet From the temperature measured by the temperature sensor 24 and the flow rate of the exhaust gas detected by the exhaust gas flow rate detection unit 11, the heat exchange amount Q1 between the exhaust gas and the heat medium in the heat exchange unit 2 can be calculated.

  From the foregoing description, many modifications and other embodiments of the present invention are apparent to persons skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The fuel cell system of the present invention is useful in a fuel cell system that requires both water independence and high economic efficiency.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Heat exchange part 3 Heat radiation part 4 Storage tank 5 Heater 6 Calculation part 7 Output control part 8 Circulation flow path 9 Heat medium flow rate detection part 10 Exhaust gas flow path 11 Exhaust gas flow rate detection part 21 1st heat exchange part inlet temperature sensor 22 1st heat exchanging part exit temperature sensor 23 2nd heat exchanging part entrance temperature sensor 24 2nd heat exchanging part exit temperature sensor 33 heat dissipation part entrance temperature sensor 34 heat dissipating part exit temperature sensor 41 detection part 61 1st heat exchange amount calculation part 62 Second heat exchange amount calculation unit 63 Heater output detection unit 64 Heat dissipation margin calculation unit

Claims (5)

A fuel cell;
Heat exchange between the exhaust gas discharged from the fuel cell and the heat medium, a temperature of the exhaust gas is reduced, and a heat exchange unit recovers water used for power generation of the fuel cell;
A storage tank for storing the heat medium heated by heat exchange with the exhaust gas in the heat exchange unit;
A detection unit for detecting a temperature state of the heat medium in the storage tank;
A circulation channel for circulating the heat medium in the storage tank through the heat exchange unit;
A heat dissipating part for dissipating the heat medium flowing through the circulation channel;
A heater for heating the heat medium flowing through the circulation channel;
The value of the heat radiating part is a value obtained by subtracting the amount of heat transferred to the heat medium in the heat exchange part and the heater from the maximum heat radiated amount that can be radiated from the heat medium by the heat radiating part. A calculation unit for calculating a heat dissipation margin;
An output control unit for controlling the power generation output of the fuel cell,
When the output control unit determines that the heat medium in the storage tank has reached a fully stored state based on the detection result of the detection unit, the heat dissipation margin calculated by the calculation unit is a positive value. A fuel cell system that controls the power generation output of the fuel cell to be larger than a preset minimum power generation output that is a preset lower limit value of the power generation amount of the fuel cell. The calculation unit includes:
Calculating a heat exchange amount in the heat radiating unit, a first heat exchange amount calculating unit for obtaining a maximum value of the heat dissipation amount of the heat medium;
Calculating a heat exchange amount in the heat exchange unit, thereby obtaining a second heat exchange amount calculation unit for obtaining an amount of heat transferred from the exhaust gas to the heat medium;
A heater output detector that detects the amount of heat transferred from the heater to the heat medium by detecting the amount of heat output by the heater;
The amount of heat transferred to the heat medium determined by the second heat exchange amount calculation unit and the heater output detection unit from the maximum value of the heat dissipation amount from the heat medium determined by the first heat exchange amount calculation unit. The fuel cell system according to claim 1, further comprising: a heat dissipation margin calculation unit that subtracts and calculates the heat dissipation margin of the heat dissipation unit. A heat medium flow rate detection unit for detecting the flow rate of the heat medium flowing through the circulation channel;
A heat radiation part inlet temperature sensor for measuring a heat radiation part inlet temperature which is a temperature of the heat medium flowing into the heat radiation part;
A heat radiating portion outlet temperature sensor for measuring a heat radiating portion outlet temperature which is a temperature of the heat medium flowing out from the heat radiating portion, and
The first heat exchange amount calculation unit includes:
The heat radiation part inlet temperature measured by the heat radiation part inlet temperature sensor, the heat radiation part outlet temperature measured by the heat radiation part outlet temperature sensor, and the heat flowing through the circulation channel detected by the heat medium flow rate detection part The fuel cell system according to claim 2, wherein a heat exchange amount in the heat radiating unit is calculated from a flow rate of the medium. A heat medium flow rate detection unit for detecting the flow rate of the heat medium flowing through the circulation channel;
A first heat exchange unit inlet temperature sensor that measures a heat exchange unit inlet temperature that is a temperature of the heat medium flowing into the heat exchange unit;
A first heat exchange section outlet temperature sensor that measures a heat exchange section outlet temperature that is a temperature of the heat medium flowing out of the heat exchange section,
The second heat exchange amount calculation unit
The heat exchanger inlet temperature measured by the first heat exchanger inlet temperature sensor, the heat exchanger outlet temperature measured by the first heat exchanger outlet temperature sensor, and detected by the heat medium flow detector. The fuel cell system according to claim 2, wherein a heat exchange amount in the heat exchange unit is calculated from a flow rate of the heat medium flowing through the circulation channel. An exhaust gas passage through which the exhaust gas discharged from the fuel cell flows;
An exhaust gas flow rate detection unit for detecting the flow rate of the exhaust gas flowing through the exhaust gas flow path;
A second heat exchange section inlet temperature sensor for measuring a heat exchange section inlet temperature which is a temperature of the exhaust gas flowing into the heat exchange section;
A second heat exchange part outlet temperature sensor for measuring a heat exchange part outlet temperature which is a temperature of the exhaust gas flowing out from the heat exchange part,
The second heat exchange amount calculation unit
Detected by the heat exchanger inlet temperature measured by the second heat exchanger inlet temperature sensor, the heat exchanger outlet temperature measured by the second heat exchanger outlet temperature sensor, and the exhaust gas flow rate detector. The fuel cell system according to claim 2, wherein a heat exchange amount in the heat exchange unit is calculated from a flow rate of the exhaust gas flowing through the circulation flow path.

Images