CN115911446A - Control method of fuel cell cogeneration system - Google Patents
Control method of fuel cell cogeneration system Download PDFInfo
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- CN115911446A CN115911446A CN202111165209.XA CN202111165209A CN115911446A CN 115911446 A CN115911446 A CN 115911446A CN 202111165209 A CN202111165209 A CN 202111165209A CN 115911446 A CN115911446 A CN 115911446A
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- 239000000446 fuel Substances 0.000 title claims abstract description 129
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- 238000001816 cooling Methods 0.000 claims abstract description 54
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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Abstract
The invention relates to the technical field of fuel cells, in particular to a control method of a fuel cell cogeneration system. The cooling method aims to solve the problems of large temperature fluctuation and poor operation stability of the cooling method of the existing fuel cell combined heat and power system. For the purpose, the radiator and the heat exchanger are connected by using a first three-way valve and a second three-way valve, and the control method controls a first port of the first three-way valve to be communicated with a third port and controls a second port of the second three-way valve to be communicated with the third port when receiving a power-on command; acquiring a first outlet temperature of a cooling outlet; comparing the first outlet temperature with the magnitude of the outlet lower limit temperature threshold; and selectively controlling the cooling water pump to start running or keep stopping according to the comparison result. The application can reduce the temperature fluctuation inside the fuel cell, maximize the output efficiency of the fuel cell, and ensure the high-efficiency and stable operation of the system.
Description
Technical Field
The invention relates to the technical field of fuel cells, in particular to a control method of a fuel cell cogeneration system.
Background
The fuel cell cogeneration system is generally composed of a fuel cell, a fuel supply subsystem, an oxidant supply subsystem, a water heating subsystem, a control subsystem and the like. The current commonly used fuel is hydrogen, the oxidant is air, and the operation principle of the fuel cell is as follows: hydrogen gas and air are supplied to the anode and cathode of the fuel cell, respectively, the hydrogen gas dissociates hydrogen ions and electrons at the anode, the hydrogen ions pass through an electrolyte (e.g., a proton exchange membrane) between the cathode and anode to the cathode, the electrons are conducted to the cathode through an external circuit, and oxygen in the air combines with the hydrogen ions and electrons at the cathode to produce water. The electrons generate current in the process of conduction through an external circuit, and meanwhile, due to the electrochemical reaction of the fuel cell and the internal resistance of the fuel cell, the fuel cell can also generate certain heat, the generated current can be used for supplying power to the outside, and the generated heat is used for supplying heat to the outside.
To ensure that the performance of the fuel cell is in a better state, the fuel cell needs to be cooled. Set up independent refrigerated cooling water tank and fuel cell among the prior art and carry out the heat transfer that circulates usually, the heat that exchanges simultaneously can also carry out the heat exchange with the heat storage water tank, heats a hot water tank. However, the cooling method causes large temperature fluctuation of the fuel cell, and the system operation stability is poor.
Accordingly, there is a need in the art for a new control method for a fuel cell cogeneration system that addresses the above-mentioned problems.
Disclosure of Invention
In order to solve at least one of the above problems in the prior art, namely to solve the problems of large temperature fluctuation and poor operation stability of the cooling method of the conventional fuel cell cogeneration system, the present application provides a control method of the fuel cell cogeneration system, wherein the fuel cell cogeneration system comprises a fuel cell, a radiator, a heat exchanger, a first three-way valve, a second three-way valve, a holding water tank, a cooling water pump and a circulating water pump,
a cooling outlet of the fuel cell is communicated with a first port of the first three-way valve, a second port of the first three-way valve is communicated with an inlet of the radiator, an outlet of the radiator is communicated with a first port of the second three-way valve, a second port of the second three-way valve is communicated with a cooling inlet of the fuel cell, the cooling water pump is disposed between the cooling outlet and the first port of the first three-way valve or between the second port of the second three-way valve and the cooling inlet,
the third port of the first three-way valve is communicated with the first heat exchange inlet of the heat exchanger, the first heat exchange outlet of the heat exchanger is communicated with the third port of the second three-way valve,
the water outlet of the heat-preservation water tank is communicated with the second heat exchange inlet of the heat exchanger, the second heat exchange outlet of the heat exchanger is communicated with the water inlet of the heat-preservation water tank, the circulating water pump is arranged between the water outlet and the second heat exchange inlet or between the second heat exchange outlet and the water inlet,
the control method comprises the following steps:
when an electrifying instruction is received, controlling a first port of the first three-way valve to be communicated with a third port, and controlling a second port of the second three-way valve to be communicated with the third port;
acquiring a first outlet temperature of the cooling outlet;
comparing the first outlet temperature with a lower outlet temperature threshold;
and selectively controlling the cooling water pump to start operation or keep stopping according to the comparison result.
In a preferable embodiment of the control method of the fuel cell cogeneration system, the step of selectively controlling the cooling water pump to start or stop according to the comparison result further includes:
if the first outlet temperature is greater than or equal to the outlet lower limit temperature threshold value, controlling the cooling water pump to start to operate;
and controlling the cooling water pump to keep stopping if the first outlet temperature is less than the outlet lower limit temperature threshold value.
In a preferable embodiment of the control method of the fuel cell cogeneration system, the step of "controlling the start-up operation of the cooling water pump" further includes:
determining the running rotating speed of the cooling water pump based on the first outlet temperature;
and controlling the cooling water pump to operate according to the operation rotating speed.
In a preferable embodiment of the control method of the fuel cell cogeneration system, the step of determining the operating rotation speed of the cooling water pump based on the first outlet temperature further includes:
and determining the operation rotating speed of the cooling water pump based on the corresponding relation curve between the first outlet temperature and the operation rotating speed.
In a preferred embodiment of the control method for the cogeneration system with a fuel cell, after the step of "controlling the cooling water pump to start operating", the control method further includes:
obtaining a second outlet temperature of the cooling outlet;
comparing the magnitude of the second outlet temperature to the outlet lower temperature threshold;
and if the second outlet temperature is less than or equal to the outlet lower limit temperature threshold value, controlling the cooling water pump to stop running, controlling the first three-way valve to be switched to a first port to be communicated with a second port, and controlling the first port of the second three-way valve to be communicated with the second port.
In a preferable aspect of the control method for a cogeneration system for a fuel cell, the control method further includes:
if the second outlet temperature is greater than the lower outlet temperature threshold, further comparing the magnitude of the second outlet temperature to an upper outlet temperature threshold;
if the second outlet temperature is greater than or equal to the outlet upper limit temperature threshold value, controlling the cooling water pump to operate at the maximum rotating speed;
and if the second outlet temperature is less than the outlet upper limit temperature threshold value, controlling the cooling water pump to keep running.
In a preferable embodiment of the control method of the co-generation system for a fuel cell, after the step of "controlling the cooling water pump to start operation", the control method further includes:
obtaining an inlet temperature of the cooling inlet;
comparing the inlet temperature with an inlet upper limit temperature threshold;
and if the inlet temperature is greater than or equal to the inlet upper limit temperature threshold value, controlling the first three-way valve to be switched to a first port to be communicated with a second port, and controlling the first port of the second three-way valve to be communicated with the second port.
In a preferable embodiment of the control method for a combined heat and power system for a fuel cell, the control method further includes:
if the inlet temperature is less than the upper inlet temperature threshold, further comparing the inlet temperature with a lower inlet temperature threshold;
and if the inlet temperature is less than or equal to the inlet lower limit temperature threshold value, controlling the first port of the first three-way valve to be communicated with the third port, and controlling the second port of the second three-way valve to be communicated with the third port.
In a preferable embodiment of the control method of the fuel cell cogeneration system, the heat-retaining water tank is provided with an auxiliary heater, and the control method further includes:
when the cooling water pump stops operating, acquiring the water tank temperature of the heat-preservation water tank;
comparing the water tank temperature with the water tank lower limit temperature threshold value;
if the water tank temperature is less than or equal to the water tank lower limit temperature threshold, further judging that useless heat needs exist at present;
the auxiliary heater is turned on when there is a useful heat demand.
In a preferable aspect of the control method for a cogeneration system for a fuel cell, the control method further includes:
if the water tank temperature is greater than the water tank lower limit temperature threshold, further judging the water tank temperature and the water tank upper limit temperature threshold;
if the water tank temperature is greater than or equal to the water tank upper limit temperature threshold, controlling the auxiliary heater to be turned off;
and if the auxiliary heater is in a closed state and the temperature of the water tank is greater than or equal to the upper limit temperature threshold value of the water tank, stopping the control system.
Through the control method, the radiator and the heat exchanger are simultaneously connected with the cooling loop of the fuel cell, and the switching of the cooling loop is realized through the first three-way valve and the second three-way valve, so that the stability of the temperature environment of the fuel cell cogeneration system during operation can be improved, the temperature fluctuation in the fuel cell is reduced, the output efficiency of the fuel cell is utilized to the maximum extent, and the efficient and stable operation of the system is ensured.
Drawings
The control method of the fuel cell cogeneration system of the present application is described below with reference to the drawings.
In the drawings:
FIG. 1 is a schematic system diagram of a portion of a fuel cell cogeneration system of the present application;
fig. 2 is a flowchart of a control method of the fuel cell cogeneration system of the present application;
fig. 3 is a flowchart of a control method of the fuel cell cogeneration system of the present application for adjusting based on a second outlet temperature of the cooling outlet;
FIG. 4 is a flow chart of a control method of the fuel cell cogeneration system of the present application for regulating based on an inlet temperature of the cooling inlet;
fig. 5 is a flowchart of the control method of the fuel cell cogeneration system of the present application, which performs adjustment based on the tank temperature.
List of reference numerals
1. A fuel cell; 2. a heat sink; 21. a heat radiation fan; 3. a heat exchanger; 4. a first three-way valve; 41. a first port of a first three-way valve; 42. a second port of the first three-way valve; 43. a third port of the first three-way valve; 5. a second three-way valve; 51. a first port of a second three-way valve; 52. a second port of the second three-way valve; 53. a third port of the second three-way valve; 6. a heat preservation water tank; 7. a cooling water pump; 8. a water circulating pump; 9. an auxiliary heater.
Detailed Description
Preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principles of the present application, and are not intended to limit the scope of protection of the present application. For example, although the following detailed steps of the method of the present application are described in detail, a person skilled in the art can combine, separate and change the order of the following steps without departing from the basic principle of the present application, and the technical solution thus modified does not change the basic concept of the present application and therefore falls within the protection scope of the present application.
Referring first to fig. 1, the fuel cell cogeneration system of the present application will be briefly described. Fig. 1 is a partial system diagram of a fuel cell cogeneration system according to the present application.
As shown in fig. 1, in one possible embodiment, the fuel cell 1 cogeneration system mainly includes a fuel cell 1, a radiator 2, a heat exchanger 3, a first three-way valve 4, a second three-way valve 5, a holding water tank 6, a cooling water pump 7, a circulating water pump 8, and an auxiliary heater 9. The fuel cell 1 has a fuel inlet, a fuel outlet, an oxidant inlet, an oxidant outlet, and a cooling inlet and a cooling outlet. The fuel inlet and the fuel outlet communicate with a fuel supply system to enable supply of fuel and discharge of remaining fuel, and the oxidant inlet and the oxidant outlet communicate with an oxidant supply system to enable supply of oxidant and discharge of reaction products and remaining oxidant. The arrangement of the fuel cell is common knowledge in the art and will not be described in detail.
In the present application, the cooling inlet and the cooling outlet communicate with a cooling circuit to achieve cooling of the fuel cell 1. Specifically, the cooling outlet of the fuel cell 1 communicates with the first port 41 of the first three-way valve 4, the second port 42 of the first three-way valve 4 communicates with the inlet of the radiator 2, and the third port 43 of the first three-way valve 4 communicates with the first heat exchange inlet of the heat exchanger 3. The outlet of the radiator 2 communicates with a first port 51 of the second three-way valve 5, a second port 52 of the second three-way valve 5 communicates with a cooling inlet of the fuel cell 1, and a third port 53 of the second three-way valve 5 communicates with a first heat exchange outlet of the heat exchanger 3. In this application, the first three-way valve 4 and the second three-way valve 5 both adopt electromagnetic three-way valves, and the communication between the first port 41 and the second port 42 or the communication between the first port 41 and the third port 43 can be realized by controlling the reversing of the first three-way valve 4, and the communication between the second port 52 and the first port 51 or the communication between the second port 52 and the third port 53 can be realized by controlling the reversing of the second three-way valve 5.
The radiator 2 is preferably an air-cooled radiator 2 including a coil and fins, both ends of which are communicated with the second port 42 of the first three-way valve 4 and the first port 51 of the second three-way valve 5, respectively, and is provided with a radiator fan 21. Heat exchanger 3 can adopt shell-and-tube heat exchanger 3, shell-and-tube heat exchanger 3 includes the casing and sets up in the inside coil pipe of casing, be provided with first heat transfer import and first heat transfer export on the casing, the coil pipe both ends are stretched out the casing and are imported and the export of second heat transfer as second heat transfer, first heat transfer import communicates with first three-way valve 4's third port 43, first heat transfer export communicates with second three-way valve 5's third port 53, the import of second heat transfer communicates with holding water box 6's delivery port, the export of second heat transfer communicates with holding water box 6's water inlet.
The cooling water pump 7 is arranged between the cooling outlet and the first port 41 of the first three-way valve 4, and the circulating water pump 8 is arranged between the water outlet of the heat preservation water tank 6 and the second heat exchange inlet. The outlet of the heat preservation water tank 6 is communicated with the resident water supply end through the auxiliary heater 9, and the resident water supply end and the water inlet of the heat preservation water tank 6 are also respectively communicated with tap water. The auxiliary heater 9 may be an electric heater, a ceramic heater, or the like.
When the cogeneration system of the fuel cell 1 is operated, on the one hand, the fuel gas and the oxidant gas are supplied to the inside of the fuel cell 1, so that the inside of the fuel cell 1 reacts to generate electric energy, and the generated electric energy can be used by a user. On the other hand, during the reaction, the fuel cell 1 emits heat, and at this time, the flow of the coolant is controlled by controlling the first three-way valve 4 and the second three-way valve 5. For example, the first port 41 of the first three-way valve 4 is controlled to communicate with the second port 42, the first port 51 of the second three-way valve 5 is controlled to communicate with the second port 52, the cooling water pump 7 is turned on, and the heat released from the fuel cell 1 is radiated to the environment by the radiator 2. For another example, the first port 41 of the first three-way valve 4 is controlled to communicate with the third port 43, the second port 52 of the second three-way valve 5 is controlled to communicate with the third port 53, the cooling water pump 7 and the circulating water pump 8 are turned on, and heat released from the fuel cell 1 is exchanged to the hot water tank 6 through the heat exchanger 3.
Of course, the specific arrangement of the co-generation system of the fuel cell 1 is only used for illustrating the principle of the present application, and is not intended to limit the scope of the present application, and those skilled in the art can adjust the system to adapt the adjusted system to a more specific application scenario without departing from the principle of the present application. For example, the cooling water pump 7 may be disposed between the second heat exchange outlet and the water inlet, and the circulating water pump 8 may be disposed between the second port of the second three-way valve 5 and the cooling inlet. For another example, the specific forms of the radiator 2 and the heat exchanger 3 are not limited, and a person skilled in the art may select the specific forms based on actual needs, for example, the radiator 2 may also be a heat sink or a water-cooled radiator 2, and the heat exchanger 3 may also be a double-pipe heat exchanger 3.
Note that, in the control method of the embodiment described below, for convenience of description, the case where the first port 41 of the first three-way valve 4 is communicated with the second port 42, and the first port 51 of the second three-way valve 5 is communicated with the second port 52 is simply referred to as being communicated with the radiator 2, and the case where the first port 41 of the first three-way valve 4 is communicated with the third port 43, and the second port 52 of the second three-way valve 5 is communicated with the third port 53 is simply referred to as being communicated with the heat exchanger 3.
Next, referring to fig. 2, a control method of the fuel cell cogeneration system of the present application will be described. Fig. 2 is a flowchart of a control method of the fuel cell cogeneration system of the present application.
As shown in fig. 2, the control method of the fuel cell cogeneration system of the present application includes:
s101, when an electrifying instruction is received, controlling a first three-way valve and a second three-way valve to be communicated with a heat exchanger; for example, when the fuel cell cogeneration system receives a power-on command and needs to work, the system is powered on, and the first three-way valve and the second three-way valve are controlled to be communicated with the heat exchanger, and at the moment, the cooling water circulation of the fuel cell and the water circulation of the heat-preservation water tank can directly exchange heat.
S103, acquiring a first outlet temperature of the cooling outlet; for example, since a temperature sensor is provided at the cooling outlet of the fuel cell to obtain the first outlet temperature, and the measurement of the internal stack temperature of the fuel cell is difficult in practical applications, the temperature of the cooling outlet of the fuel cell is approximated to the temperature of the fuel cell, so as to indirectly control the internal stack temperature of the fuel cell.
S105, comparing the first outlet temperature with the outlet lower limit temperature threshold; the lower outlet temperature limit is determined based on the optimal outlet temperature when the fuel cell has better performance, and the inventor finds that the outlet temperature is 63-67 ℃ when the fuel cell has better performance, the optimal outlet temperature is 65 ℃ in the application for illustration, and the lower outlet temperature threshold can float downward 1-3 ℃ on the basis of 65 ℃, for example, the lower outlet temperature threshold is 63 ℃. And after the first outlet temperature is obtained, comparing the first outlet temperature with an outlet lower limit temperature threshold value.
Of course, the specific value of the lower threshold of the outlet temperature is not exclusive, and the skilled person can choose the lower threshold value specifically based on different fuel cell characteristics.
S107, selectively controlling the cooling water pump to start or keep stopping according to the comparison result; specifically, if the first outlet temperature is greater than or equal to the outlet lower limit temperature threshold, controlling the cooling water pump to start to operate; and if the first outlet temperature is less than the lower outlet limit temperature threshold, controlling the cooling water pump to keep stopping.
For example, when the first outlet temperature is greater than or equal to the outlet lower limit temperature threshold, it is proved that the temperature of the fuel cell rises and approaches or reaches the optimal operating temperature, and at this time, the temperature rising speed needs to be delayed to keep the temperature within a preferred temperature range, so that the cooling water pump is started, and the cooling water pump is used for driving the cooling water to exchange heat with the water in the heat preservation water tank, so as to control the outlet temperature of the fuel cell. At this time, of course, the circulating water pump is also required to be started to realize the heat exchange between the cooling water and the water in the heat-preservation water tank in the heat exchanger.
The technical personnel in the field can understand that when adopting above-mentioned control mode, because the water in the holding water box all has certain temperature usually, consequently adopt the direct and cooling water of water in the holding water box to carry out the heat exchange, can reduce the temperature fluctuation of cooling water to make the temperature change in the fuel cell mild, the maximize utilizes fuel cell's output efficiency, guarantees the high-efficient steady operation of system.
In one possible embodiment, the step of "controlling the cooling water pump to start operation" further includes: determining the running rotating speed of the cooling water pump based on the first outlet temperature; and controlling the cooling water pump to operate according to the operating rotating speed. Preferably, the operating rotational speed of the cooling water pump is determined based on a correspondence curve between the first outlet temperature and the operating rotational speed.
For example, the applicant conducted experiments based on the correspondence between the optimum outlet temperature and the actually detected first outlet temperature, and obtained an influence curve of the rotational speed of the cooling water pump on the outlet temperature from experimental tests, which curve indicates the correspondence between the rotational speed of the cooling water pump and the current first outlet temperature. After the rotating speed of the cooling water pump is selected according to the outlet temperature on the curve to operate, the outlet temperature can be stabilized around the optimal outlet temperature, the better output efficiency of the fuel cell is ensured, and the temperature fluctuation when the cooling water pump is started is reduced.
Of course, besides the influence curve obtained through experimental tests, the person skilled in the art may also determine the operating speed of the cooling water pump in other ways, such as obtaining a comparison table between the speed of the cooling water pump and the outlet temperature through experiments or empirical formulas, and then determining the speed of the cooling water pump through the comparison table.
A preferred embodiment of the present application will be described below with reference to fig. 3 to 5. Fig. 3 is a flowchart of adjusting the second outlet temperature based on the cooling outlet in the control method of the fuel cell cogeneration system of the application; FIG. 4 is a flow chart of a control method of the fuel cell cogeneration system of the present application for regulating based on an inlet temperature of the cooling inlet; fig. 5 is a flowchart of the control method of the fuel cell cogeneration system of the present application, which performs adjustment based on the tank temperature.
Referring first to fig. 3, in a preferred embodiment, after the step of "controlling the cooling water pump to start operation", the control method further includes: acquiring a second outlet temperature of the cooling outlet; comparing the second outlet temperature with the magnitude of the outlet lower limit temperature threshold; and if the second outlet temperature is less than or equal to the outlet lower limit temperature threshold value, controlling the cooling water pump to stop running, and controlling the first three-way valve and the second three-way valve to be switched to be communicated with the radiator. If the second outlet temperature is greater than the lower outlet temperature threshold, further comparing the magnitude of the second outlet temperature with the upper outlet temperature threshold; if the second outlet temperature is greater than or equal to the outlet upper limit temperature threshold value, controlling the cooling water pump to operate at the maximum rotating speed; and controlling the cooling water pump to keep running if the second outlet temperature is less than the outlet upper limit temperature threshold value.
After the cooling water pump is controlled to start and operate, the temperature of the cooling outlet can be changed, the outlet water temperature of the cooling outlet is monitored, the operation stability of the system can be further improved, and temperature fluctuation is reduced.
For example, the outlet lower limit temperature threshold is still 63 ℃, step S201 is executed, after the second outlet temperature of the cooling outlet is obtained, step S203 is executed, the second outlet temperature is compared with the outlet lower limit temperature threshold, and when the second outlet temperature is less than or equal to the outlet lower limit temperature threshold, it indicates that the outlet temperature is further reduced by the start of the cooling water pump, and is already less than the preferred operating temperature range of the fuel cell. Step S205 is executed at the moment, the cooling water pump is controlled to stop running, and the first three-way valve and the second three-way valve are controlled to be switched to be communicated with the radiator, so that on one hand, the cooling water pump is stopped to drive cooling water to circulate, and heat loss is reduced; on the other hand, the temperature drops too fast, possibly due to the lower temperature of the holding tank, and therefore switching to the radiator line avoids further heat exchange with the holding tank. At the moment, the cooling fan does not need to be started or only needs to operate at a lower rotating speed.
Otherwise, if the second outlet temperature is greater than the outlet lower limit temperature threshold, step S207 is executed to further compare the magnitude of the second outlet temperature with the outlet upper limit temperature threshold. The setting mode of the outlet upper limit temperature threshold is similar to that of the outlet lower limit temperature threshold, except that the outlet upper limit temperature threshold floats upwards by 1-3 ℃ on the basis of the optimal outlet temperature, and the outlet upper limit temperature threshold can be 67 ℃. Of course, the specific value of the upper threshold of the outlet temperature is not exclusive and can be selected by those skilled in the art based on different characteristics of the fuel cell.
When the second outlet temperature is greater than or equal to the outlet upper limit temperature threshold value, the outlet temperature is proved to be higher and is already higher than the preferred working temperature interval of the fuel cell. At this time, step S209 is performed to control the cooling water pump to operate at the maximum rotation speed to rapidly decrease the outlet temperature. Of course, although the cooling water pump is already operated at the maximum rotation speed, the temperature change is gentle and temperature fluctuation does not occur because the first three-way valve and the second three-way valve are still communicated with the heat exchanger at the moment. Conversely, if the second outlet temperature is less than the outlet upper temperature threshold at this time, it is verified that the fuel cell is operating within the preferred operating temperature range. At this time, step S211 is executed, and it is only necessary to maintain the current operation state, that is, to maintain the operation rotation speed of the cooling water pump determined based on the first outlet temperature, and then to control the cooling water pump to operate at the operation rotation speed.
Referring next to fig. 4, in a preferred embodiment, after the step of "controlling the cooling water pump to start operation", the control method further includes: acquiring the inlet temperature of a cooling inlet; comparing the inlet temperature with the inlet upper limit temperature threshold; and if the inlet temperature is greater than or equal to the inlet upper limit temperature threshold value, controlling the first three-way valve and the second three-way valve to be switched to be communicated with the radiator. If the inlet temperature is less than the inlet upper limit temperature threshold, further comparing the inlet temperature with the inlet lower limit temperature threshold; and if the inlet temperature is less than or equal to the inlet lower limit temperature threshold value, controlling the first three-way valve and the second three-way valve to be communicated with the heat exchanger.
After controlling cooling water pump start-up operation, the temperature of cooling export can change, and the temperature of cooling import also can change simultaneously, and the inventor finds that keeps fuel cell's import temperature and export temperature at certain difference in temperature, can improve fuel cell's operating stability. Therefore, the operation efficiency of the system can be further improved and the temperature fluctuation can be reduced by monitoring the inlet water temperature of the cooling inlet.
For example, the inventors have found experimentally that the temperature difference between the inlet temperature and the outlet temperature of the fuel cell is between 3 ℃ and 7 ℃ when the fuel cell is in better performance, and if the outlet optimum temperature is 65 ℃, the inlet optimum temperature can be 60 ℃ in the present application, and then the inlet upper temperature threshold and the inlet lower temperature threshold can be shifted by 1 ℃ to 3 ℃ from top to bottom on the basis of 60 ℃, for example, the inlet lower temperature threshold is 58 ℃ and the inlet upper temperature threshold is 62 ℃. Of course, the specific values of the upper/lower threshold values of the inlet temperature are not exclusive and can be selected by those skilled in the art based on different fuel cell characteristics.
After the inlet temperature is acquired by executing step S301, step S303 is executed to compare the inlet temperature with the inlet upper limit temperature threshold. When the inlet temperature is greater than or equal to the inlet upper limit temperature threshold, the inlet temperature is proved to be higher at the moment, which is not beneficial to the heat dissipation of the fuel cell. At this time, step S305 is executed to control the first three-way valve and the second three-way valve to communicate with the radiator and control the cooling fan to be turned on, so as to rapidly reduce the inlet temperature.
Otherwise, if the inlet temperature is less than the inlet upper limit temperature threshold, step S307 is executed to further compare the inlet temperature with the inlet lower limit temperature threshold. When the inlet temperature is less than or equal to the inlet lower limit temperature threshold, the inlet temperature is lower, which causes the temperature of the fuel cell to be reduced too fast, and is not favorable for the fuel cell to work in a better temperature range. At this time, step S309 is executed, the first three-way valve and the second three-way valve are controlled to be switched to be communicated with the heat exchanger, and the water in the holding water tank and the cooling water are used for heat exchange, so as to slow down the temperature reduction speed. Conversely, if the inlet temperature is greater than the inlet upper limit temperature threshold, the inlet temperature is proved to be in a more rational state, and the fuel cell is also operated in a better working temperature range. In this case, step S311 is executed, and it is only necessary to maintain the current operation state, that is, to maintain the operation speed of the cooling water pump determined based on the first outlet temperature, and then to control the cooling water pump to operate at the operation speed.
In a preferred embodiment, when the inlet temperature is less than or equal to the inlet lower limit temperature threshold and the first three-way valve and the second three-way valve are already in the condition of being communicated with the heat exchanger, the heater can be additionally and separately arranged in the heat-preservation water tank, and the heater is turned on to heat the water in the heat-preservation water tank so as to meet the temperature rise requirement of the cooling inlet.
Referring finally to fig. 5, in a preferred embodiment, the control method further comprises: when the cooling water pump stops operating, acquiring the water tank temperature of the heat-preservation water tank; comparing the water tank temperature with the water tank lower limit temperature threshold value; if the temperature of the water tank is less than or equal to the lower limit temperature threshold of the water tank, further judging that useless heat is needed currently; when the useful heat is needed, the auxiliary heater is started; otherwise, the current state is maintained. If the water tank temperature is higher than the water tank lower limit temperature threshold, the water tank temperature and the water tank upper limit temperature threshold are further judged; if the temperature of the water tank is greater than or equal to the upper limit temperature threshold of the water tank, controlling the auxiliary heater to be closed; and if the temperature of the water tank is less than the upper limit temperature threshold value of the water tank, the current state is kept. And if the auxiliary heater is in a closed state and the temperature of the water tank is greater than or equal to the upper limit temperature threshold value of the water tank, stopping the control system.
The application of the fuel cell cogeneration system mainly lies in supplying power and heat to users, and the main source of the heat of the water in the heat-preservation water tank lies in the heat emitted by the fuel cell. And once the cooling water pump stops operating, the heat exchange between the holding water tank and the fuel cell will stop, and at this moment, if the user has a heat demand, the water temperature in the holding water tank may not be satisfied. Consequently, through monitoring the water tank temperature in the holding water tank, can satisfy user's heat demand, guarantee user's use and experience.
For example, when the cooling water pump stops operating, the method mainly includes: the first outlet temperature is lower than the outlet lower limit temperature threshold value after the system is started, the second outlet temperature is lower than or equal to the outlet lower limit temperature threshold value, the system is in a shutdown state to operate, and the like. The set temperature of the water tank is the temperature usually set by a user, generally, the temperature is allowed to be actively set by the user, and can also be fixedly set when leaving a factory, the set temperature of the water tank is 55 ℃, then the upper limit temperature threshold value and the lower limit temperature threshold value of the water tank can float up and down for 1-3 ℃ on the basis of 55 ℃, for example, the lower limit temperature threshold value of the water tank is 53 ℃, and the upper limit temperature threshold value of the water tank is 57 ℃. Of course, the above-mentioned water tank temperature and the upper/lower threshold values of the water tank temperature are only used for illustrating the principles of the present application, and are not used for limiting the scope of the present application, and those skilled in the art may select the above-mentioned parameters based on different application scenarios.
After the water tank temperature is acquired in step S401, step S403 is performed to compare the water tank temperature with the water tank lower limit temperature threshold. When the temperature of the water tank is less than or equal to the lower limit temperature threshold of the water tank, the fact that the temperature of the water tank is lower at the moment is proved, and heat required by a user cannot be provided. At this time, step S405 is executed to further determine whether the user has a heat demand. Whether useful heat demand exists can be judged by arranging a flow sensor between the water tank and the resident water supply end, and when the useful heat demand of the user exists, the step S407 is executed, the auxiliary heater is started to quickly heat the outlet water of the water tank, and the requirement of the user is met. On the contrary, if the user does not have a heat demand, step S409 is performed to maintain the current state until the cooling water pump is started again to exchange heat with the water in the hot water tank using the cooling water.
Otherwise, if the water tank temperature is greater than the lower limit temperature threshold of the water tank, step S411 is executed to further compare the water tank temperature with the upper limit temperature threshold of the water tank. When the temperature of the water tank is greater than or equal to the upper limit temperature threshold of the water tank, the temperature of the water tank is higher and exceeds the set temperature of the water tank, so that the energy conservation of the system is not facilitated. At this time, step S413 is executed to further determine whether the auxiliary heater is turned off, and when the auxiliary heater is not turned off, step S415 is executed to control the auxiliary heater to be turned off so as to reduce the system energy consumption. When the sub-heater has been turned off, step S417 is performed to directly control the system shutdown to ensure the overall efficiency of the system. On the contrary, if the water tank temperature is lower than the upper limit water tank temperature threshold, it is proved that the water tank temperature is in a more rational state, and at this time, step S409 is executed, and only the current operation state needs to be maintained.
In conclusion, the radiator and the heat exchanger are simultaneously connected with the cooling loop of the fuel cell, and the switching of the cooling loop is realized through the first three-way valve and the second three-way valve, so that the stability of the temperature environment of the fuel cell cogeneration system during operation can be improved, the temperature fluctuation in the fuel cell is reduced, the output efficiency of the fuel cell is utilized to the maximum extent, and the efficient and stable operation of the system is ensured. Through monitoring the temperature of cooling outlet, the temperature of cooling inlet and water tank temperature to adjust the system cooling mode based on the monitoring result, can further improve the temperature stability and the system efficiency of system, guarantee user's use and experience.
Those skilled in the art will appreciate that the fuel cell cogeneration system described above also includes some other known subsystems, such as a fuel supply system, an oxidant supply system, a control system, etc., which are not shown in the figures in order to unnecessarily obscure embodiments of the present disclosure.
Although the foregoing embodiments describe the steps in the above sequential order, those skilled in the art can understand that, in order to achieve the effect of the present embodiments, the different steps need not be executed in such an order, and may be executed simultaneously (in parallel) or in an inverted order, and these simple changes are all within the scope of protection of the present application.
It will be understood by those skilled in the art that although some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the claims of the present application, any of the claimed embodiments may be used in any combination. For example, the adjusting step based on the second outlet temperature, the adjusting step based on the inlet temperature, and the adjusting step based on the tank temperature may be performed in parallel, may be performed sequentially, or may be selectively performed by only some of the steps by those skilled in the art, without departing from the principles of the present application.
So far, the technical solutions of the present application have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of protection of the present application is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the present application, and the technical scheme after the changes or substitutions will fall into the protection scope of the present application.
Claims (10)
1. A control method of a fuel cell cogeneration system is characterized in that the fuel cell cogeneration system comprises a fuel cell, a radiator, a heat exchanger, a first three-way valve, a second three-way valve, a heat preservation water tank, a cooling water pump and a circulating water pump,
a cooling outlet of the fuel cell is communicated with a first port of the first three-way valve, a second port of the first three-way valve is communicated with an inlet of the radiator, an outlet of the radiator is communicated with a first port of the second three-way valve, a second port of the second three-way valve is communicated with a cooling inlet of the fuel cell, the cooling water pump is disposed between the cooling outlet and the first port of the first three-way valve or between the second port of the second three-way valve and the cooling inlet,
the third port of the first three-way valve is communicated with the first heat exchange inlet of the heat exchanger, the first heat exchange outlet of the heat exchanger is communicated with the third port of the second three-way valve,
the water outlet of the heat-preservation water tank is communicated with the second heat exchange inlet of the heat exchanger, the second heat exchange outlet of the heat exchanger is communicated with the water inlet of the heat-preservation water tank, the circulating water pump is arranged between the water outlet and the second heat exchange inlet or between the second heat exchange outlet and the water inlet,
the control method comprises the following steps:
when an electrifying instruction is received, controlling a first port of the first three-way valve to be communicated with a third port, and controlling a second port of the second three-way valve to be communicated with the third port;
obtaining a first outlet temperature of the cooling outlet;
comparing the first outlet temperature with a lower outlet temperature threshold;
and selectively controlling the cooling water pump to start operation or keep stopping according to the comparison result.
2. The control method of the fuel cell cogeneration system according to claim 1, wherein the step of selectively controlling the cooling water pump to start operation or to remain stopped according to the comparison result further comprises:
if the first outlet temperature is greater than or equal to the outlet lower limit temperature threshold value, controlling the cooling water pump to start to operate;
and if the first outlet temperature is smaller than the outlet lower limit temperature threshold, controlling the cooling water pump to keep stopping.
3. The control method of the fuel cell cogeneration system according to claim 2, wherein the step of "controlling the cooling water pump to start operation" further comprises:
determining the running rotating speed of the cooling water pump based on the first outlet temperature;
and controlling the cooling water pump to operate according to the operating rotating speed.
4. The control method of the fuel cell cogeneration system according to claim 3, wherein the step of determining the operating rotational speed of the cooling water pump based on the first outlet temperature further comprises:
and determining the operation rotating speed of the cooling water pump based on the corresponding relation curve between the first outlet temperature and the operation rotating speed.
5. The control method of a fuel cell cogeneration system according to claim 1, wherein after the step of "controlling the cooling water pump to start operating", the control method further comprises:
obtaining a second outlet temperature of the cooling outlet;
comparing the magnitude of the second outlet temperature to the outlet lower temperature threshold;
and if the second outlet temperature is less than or equal to the outlet lower limit temperature threshold value, controlling the cooling water pump to stop running, controlling the first three-way valve to be switched to a first port to be communicated with a second port, and controlling the first port of the second three-way valve to be communicated with the second port.
6. The control method of a fuel cell cogeneration system according to claim 5, further comprising:
if the second outlet temperature is greater than the lower outlet temperature threshold, further comparing the magnitude of the second outlet temperature to an upper outlet temperature threshold;
if the second outlet temperature is greater than or equal to the outlet upper limit temperature threshold value, controlling the cooling water pump to operate at the maximum rotating speed;
and if the second outlet temperature is less than the outlet upper limit temperature threshold value, controlling the cooling water pump to keep running.
7. The control method of a fuel cell cogeneration system according to claim 1, wherein after the step of "controlling the cooling water pump to start operating", the control method further comprises:
obtaining an inlet temperature of the cooling inlet;
comparing the inlet temperature with an inlet upper limit temperature threshold;
and if the inlet temperature is greater than or equal to the inlet upper limit temperature threshold value, controlling the first three-way valve to be switched to a first port to be communicated with a second port, and controlling the first port of the second three-way valve to be communicated with the second port.
8. The control method of the fuel cell cogeneration system according to claim 7, further comprising:
if the inlet temperature is less than the upper inlet temperature threshold, further comparing the inlet temperature with a lower inlet temperature threshold;
and if the inlet temperature is less than or equal to the inlet lower limit temperature threshold value, controlling the first port of the first three-way valve to be communicated with the third port, and controlling the second port of the second three-way valve to be communicated with the third port.
9. The control method of a fuel cell cogeneration system according to claim 2 or 5, wherein said holding water tank is provided with an auxiliary heater, said control method further comprising:
when the cooling water pump stops operating, acquiring the water tank temperature of the heat-preservation water tank;
comparing the water tank temperature with a water tank lower limit temperature threshold value;
if the temperature of the water tank is less than or equal to the lower limit temperature threshold of the water tank, further judging that useless heat is needed currently;
the auxiliary heater is turned on when there is a useful heat demand.
10. The control method of a fuel cell cogeneration system according to claim 9, further comprising:
if the water tank temperature is greater than the water tank lower limit temperature threshold, further judging the water tank temperature and the water tank upper limit temperature threshold;
if the water tank temperature is greater than or equal to the water tank upper limit temperature threshold, controlling the auxiliary heater to be turned off;
and if the auxiliary heater is in a closed state and the temperature of the water tank is greater than or equal to the upper limit temperature threshold value of the water tank, stopping the control system.
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| CN202111165209.XA CN115911446A (en) | 2021-09-30 | 2021-09-30 | Control method of fuel cell cogeneration system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116344863A (en) * | 2023-05-17 | 2023-06-27 | 武汉海亿新能源科技有限公司 | Combined heat and power thermal management system of multi-fuel cell system and control method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116344863A (en) * | 2023-05-17 | 2023-06-27 | 武汉海亿新能源科技有限公司 | Combined heat and power thermal management system of multi-fuel cell system and control method thereof |
| CN116344863B (en) * | 2023-05-17 | 2023-08-18 | 武汉海亿新能源科技有限公司 | Combined heat and power thermal management system of multi-fuel cell system and control method thereof |
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