A fuel cell waste heat utilization system and control method thereof

Abstract

The present invention relates to the field of fuel cells and cogeneration, and in particular to a fuel cell waste heat utilization system and a control method thereof. The present application aims to solve the problems of low waste heat utilization efficiency and precise control of user-end heat temperature in existing fuel cell cogeneration systems. The fuel cell cogeneration system of the present application includes: a fuel cell stack, a stack heat balance device, a waste heat utilization device, an energy storage device, and a control device. By regulating the flow of the water pump in the waste heat control device and the angle of the electric control valve, the flow of heat exchange to the water tank and the heater is adjusted, thereby achieving precise control of the user-end temperature. By dynamically switching between multiple modes such as electricity demand priority, heating priority, and hot water storage priority, the efficient operation of the fuel cell system and the maximum utilization of waste heat are ensured.

Description

Technical Field

[0001] The invention relates to a fuel cell waste heat utilization system and a control method thereof. Background Art

[0002] As an efficient and clean energy conversion device, fuel cells directly convert the chemical energy in fuels into electrical energy and thermal energy. The fuel cell cogeneration system realizes both power supply and heating for users on the basis of energy gradient operation. It does not emit any pollutants during operation and has high application and environmental protection value. The fuel cell cogeneration system mainly adopts a simple waste heat recovery device to directly use the waste heat generated by the fuel cell for heating and hot water. The fuel cell cogeneration system transfers the waste heat to the circulating water through a heat exchanger, and then transmits the heat to the user end. However, these traditional systems have the following problems: low temperature control accuracy, large fluctuations in indoor temperature and hot water temperature, and poor user experience; low waste heat utilization efficiency, and simple waste heat recovery methods do not fully consider the quality of waste heat and the different needs of users, resulting in some waste heat cannot be effectively utilized, and energy waste is relatively serious. Summary of the invention

[0003] In view of the above problems, the fuel cell cogeneration waste heat utilization system and control method of the present invention can realize the redistribution of waste heat and the stable supply of heat through dynamic control, solve the problems of large fluctuations in user-side heat temperature and stable fuel cell stack temperature, improve waste heat utilization efficiency, realize stable supply of hot water and heating temperature at the user end, and ensure the stability of fuel cell stack temperature.

[0004] The specific technical solutions are as follows:

[0005] A fuel cell waste heat utilization system, characterized in that it comprises: a fuel cell stack (1), a stack heat balance device, an energy storage device, and a waste heat utilization device, wherein:

[0006] The fuel cell stack is provided with an inlet and an outlet;

[0007] The stack thermal balance device comprises: a water pump (4), a stack outlet temperature sensor (5), a stack inlet temperature sensor (6), a heat exchanger (2), and an auxiliary radiator (3). The coolant flows through the fuel cell stack through the heat exchanger (2) and the auxiliary radiator (3) to maintain the thermal balance of the stack.

[0008] The heat exchanger (2) comprises a hot end and a cold end; the hot end is provided with an inlet and an outlet; the cold end is provided with two inlets and one outlet;

[0009] The energy storage device comprises an energy storage lithium battery (7) and a control switch (8);

[0010] The waste heat utilization device comprises: a first water pump (9), an electric control valve (10), a heating and cooling device (11), a second water pump (12), and a heat exchange and hot water storage tank (13);

[0011] The outlet of the heat exchanger (2) is connected to the first water pump (9), and the outlet of the first water pump (9) is connected to the inlet of the electric control valve (10); the outlet of the electric control valve is connected to the heat exchange water storage tank (13), and the heat exchange water storage tank (13) is connected to the inlet of the cold end of the heat exchanger (2), so as to form a hot water circuit;

[0012] The outlet of the electric control valve (10) is connected to the inlet of the heating and cooling device (11), and the outlet of the heating and cooling device (11) is connected to the inlet of the cold end of the heat exchanger (2), so as to form a user heating circuit;

[0013] The outlet of the heat exchange water storage tank (13) is connected to the inlet of the second water pump (12), the outlet of the second water pump (12) is connected to the inlet of the heating and radiating device (11), and the outlet of the heating and radiating device (11) is connected to the inlet of the heat exchange water storage tank (13), thereby forming a heating auxiliary circuit.

[0014] Furthermore, the heat exchange water storage tank (13) is provided with two coils, and the heat exchange fluid in the tubes is exchanged through the coils in the water tank.

[0015] Furthermore, the water pump (9) is an electronic water pump, and the flow rate to the heat exchange water storage tank (13) and the heating device is adjusted by controlling the flow rate of the water pump.

[0016] Furthermore, the electric control valve (10) regulates the distribution of fluid flow and can adjust the angle of the valve to close or open the direction of the flow toward the heating and cooling device (11).

[0017] Furthermore, the second water pump (12) is an electronic water pump, which is used to control the liquid flow in the auxiliary heating circuit, and thus control the heating temperature.

[0018] A control method for a fuel cell waste heat utilization system, characterized in that it comprises the following steps:

[0019] Step 1: Fuel cell voltage establishment;

[0020] Step 2: Monitor whether the fuel cell load has power demand, if yes, proceed to step 3;

[0021] If not, when the water temperature of the heat exchange water storage tank (13) is monitored to be lower than the set temperature, the control switch (8) is activated and the energy storage lithium battery (7) generates electricity;

[0022] When it is detected that the water temperature of the heat exchange water storage tank (13) is greater than the set temperature and the outdoor temperature and indoor temperature are less than the set temperature, the second water pump (12) is turned on to supply heat to the room;

[0023] Step 3: If it is detected that the water temperature of the heat exchange water storage tank (13), the outdoor temperature, and the indoor temperature are all lower than the set temperature, the electric control valve (10) is opened to control the flow to the heat exchange water storage tank (13) and the heating and cooling device (11), and the auxiliary radiator (3) is closed;

[0024] If the water temperature of the heat exchange water storage tank (13) is monitored to be lower than the set temperature, and the outdoor temperature and the indoor temperature are higher than the set temperature, the electric control valve (10) is opened to the heat exchange water storage tank;

[0025] If the water temperature of the heat exchange water storage tank (13) is greater than the set temperature and the indoor temperature is lower than the set temperature, the electric control valve (10) opens to the heating and cooling device;

[0026] As in the above steps, if the stacking temperature is higher than the set stacking temperature, the auxiliary radiator (3) is started;

[0027] If the water temperature of the heat exchange water storage tank (13) and the indoor temperature are monitored to be greater than the set temperature, the auxiliary radiator (3) is started.

[0028] Furthermore, the fuel cell stack (1) entry temperature and exit temperature are controlled within a target temperature range by controlling the rotation speed of the first water pump (9) and the fan rotation speed of the auxiliary radiator (3); when the waste heat utilization demand is greater than or equal to the fuel cell heat dissipation demand, the radiator fan is turned off; when the waste heat utilization demand is less than the fuel cell heat dissipation demand, the radiator fan is started based on the temperature of the entry temperature sensor (6) to reach the target rotation speed, so that the entry temperature is within the target temperature range.

[0029] Beneficial Effects

[0030] The advantages of the fuel cell waste heat utilization system of the present invention are: the waste heat utilization device can provide a continuous and stable heat source and electric energy, while ensuring the stable operation of the fuel cell. According to the user's heat demand, hot water and heating can be dynamically adjusted according to user needs; the heat exchange fluid flow is adjusted by an electric control valve to automatically distribute the waste heat of the fuel cell; the heat exchanged by the heat exchanger tank is distributed to the heating device according to the usage scenario; the distribution of fuel cell waste heat and the stable supply of heat are controlled, while improving fuel utilization and reducing the load on electricity and the battery stack; the indoor temperature of the heater and the hot water temperature are dynamically adjusted to achieve precise control of the user-side temperature and efficient utilization of waste heat, and to achieve stability of the battery stack inlet temperature and the user's dynamic heating temperature. The optimal distribution of waste heat is achieved through logical judgment, including dynamic switching of multiple modes such as electricity demand priority, heating priority, and hot water storage priority, to ensure efficient operation of the fuel cell system and maximum utilization of waste heat.

[0031] This patent achieves the optimal distribution of waste heat through dynamic logic judgment, that is, combining the opening of the electric control valve, room temperature adjustment, and water tank temperature management to realize the dynamic distribution of the heat exchange flow in the waste heat utilization system and the precise control of the temperature in the waste heat utilization system, thereby improving the waste heat utilization efficiency and user-end experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the fuel cell cogeneration waste heat utilization system of this patent;

[0033] Figure 2 The overall logic diagram of the control method of the waste heat utilization system of the fuel cell cogeneration;

[0034] Figure 3 Schematic diagram of the process of the fuel cell waste heat utilization system in the mode of using electricity but not heat;

[0035] Figure 4 Schematic diagram of the process of the fuel cell waste heat utilization system in the electricity and heat use mode;

[0036] Figure 5 Schematic diagram of the process of the fuel cell waste heat utilization system in the mode of using heat but not electricity. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] like Figure 1As shown, the fuel cell cogeneration system of the present invention comprises: a fuel cell stack, a stack heat balance device, a waste heat utilization device, and an energy storage device;

[0039] Specifically, the fuel cell stack 1 is a proton exchange membrane fuel cell stack, and its operating principle is: hydrogen and oxygen react to generate electrical energy and heat energy at the same time. In the fuel cell system, the cooling subsystem maintains the temperature balance of the fuel cell, and the fuel cell stack is provided with an inlet and an outlet. Under the action of the water pump, the coolant flows through the stack, takes away the heat generated by the fuel cell reaction, and then dissipates the heat through the radiator, cools down, and makes the temperature of the coolant reach the specified temperature before entering the fuel cell. The electrical energy is transmitted to the energy storage lithium battery 7 through the electrical circuit.

[0040] The heat balance device of the electric stack includes: a heat exchanger 2, an auxiliary radiator 3, a water pump 4, a temperature sensor for the outlet of the stack 5, and a temperature sensor for the inlet of the stack 6; the waste heat utilization device includes: a water pump 9, an electric control valve 10, a heating and cooling device 11, a second water pump 12, a heat exchanger and a heat storage tank 13; a heat exchanger and a heat storage tank battery, and a control switch;

[0041] Among them, heat exchanger 2 exchanges the heat of the inner cooling circuit of the stack to the outer circuit through the outer cooling circuit, so as to cool the stack and maintain thermal balance. Heat exchanger 2 is divided into a hot end and a cold end. The hot end has two ports, one inlet and one outlet, through which the coolant of the fuel cell flows. The cold end is mainly for peripheral cooling, that is, it is connected to the user water circuit and the user heating circuit, and is designed with two inlets and one outlet.

[0042] Auxiliary radiator 3: The function of this radiator is to dissipate heat for the fuel cell stack. The coolant of the fuel cell cooling circuit flows through the radiator to maintain the temperature of the stack at the target temperature. When the user's demand for heat is relatively large, such as in winter, the heat generated by the stack can be completely exchanged through the heat exchanger to the external circuit hot water or heating device to achieve the purpose of cooling the stack and maintaining the thermal balance of the stack. The radiator does not need to work; in summer, when the user only uses hot water and does not use heating, and the heat demand is relatively low, the radiator is used to cool the stack and maintain the thermal balance of the stack. The radiator is used as an auxiliary heat dissipation device in this cogeneration system.

[0043] Water pump 4: This water pump is an electronic water pump used to regulate the coolant flow in the fuel cell cooling circuit.

[0044] Outlet temperature sensor 5: The outlet temperature sensor measures the temperature of the coolant leaving the battery stack; Inlet temperature sensor 6: The inlet temperature sensor measures the temperature of the coolant entering the battery stack.

[0045] The energy storage battery 7 is a lithium battery. The electricity generated by the fuel cell is stored in the lithium battery storage or directly provided to the user; the energy storage device includes a battery and a control switch, which automatically powers on or off according to the system's control requirements. This function is turned on or off based on the condition that the fuel cell does not generate electricity, that is, there is no other electricity demand and the water tank temperature is lower than the set temperature (for example, the set temperature is 45°C).

[0046] Switch 8: Automatically turns on or off the power according to the control requirements of the system. This function is turned on when the fuel cell is not generating electricity, that is, there is no other electricity demand and the water tank temperature is lower than the set temperature (for example, the set temperature is 45°C).

[0047] First water pump 9: This water pump is an electronic water pump that can adjust the liquid flow in the heating circuit. The flow rate determines the temperature of the heat exchange, which in turn affects the heat exchange temperature of the hot water storage tank and the heating device, and then adjusts the indoor temperature and the temperature of the hot water storage tank. It mainly adjusts the flow rate through the main path in the waste heat utilization circuit. The specific heat exchange flow to the hot water storage and the heating device is determined by the flow rate of the waste heat utilization main path of the water pump 9 and the opening of the electric valve 10.

[0048] Electric control valve 10: The function of the electric control valve is to regulate the distribution of fluid flow; for example, in summer or when the indoor temperature is greater than 18°C, the valve in the direction of the heating device is closed, and the flow only flows to the water tank coil to exchange heat with the cold water in the water tank.

[0049] Heating and cooling device 11: exchanges heat with indoor air to maintain the indoor temperature at a predetermined level.

[0050] The second water pump 12: This water pump is an electronic water pump that can regulate the liquid flow in the pipeline. The size of the flow determines the size of the heat exchange temperature, affects the temperature of the heating device, and further regulates the indoor temperature of the heating.

[0051] Heat exchange water storage tank 13: The water tank has the functions of heat storage, heat exchange, and electric heating. Heat storage and heat exchange are common functions, and the electric heating function cooperates with the intelligent switch and energy storage battery as a backup to provide electric heating for the water tank. Furthermore, the heat exchange water storage tank 13 has multiple heat exchange coils and interfaces, and has a temperature sensor and auxiliary heating function.

[0052] The main purpose of the present invention is to make full use of the waste heat of the fuel cell. Some waste heat utilization may not be synchronized with the use of heat and electricity during operation. This patent can provide a continuous and stable heat source and electricity through a waste heat utilization device, while ensuring the stable operation of the fuel cell.

[0053] The waste heat utilization device consists of three circuits, including a user hot water circuit, a user heating circuit and a heating auxiliary circuit.

[0054] like Figure 1, hot water circuit: the outlet of the heat exchanger 2 is connected to the first water pump 9, the outlet of the water pump is connected to the inlet of the electric control valve, the outlet of the electric control valve is connected to the coil interface of the water tank, and the coil outlet of the water tank is connected to the inlet of the heat exchanger 2 to form a liquid flow circuit;

[0055] User heating circuit: the outlet of the heat exchanger 2 is connected to the first water pump 9, the outlet of the water pump is connected to the inlet of the electric control valve, the outlet of the electric control valve is connected to the inlet of the heating radiator 11, and the heating outlet is connected to the inlet of the heat exchanger to form a liquid flow circuit;

[0056] The heating auxiliary circuit, i.e., the heating auxiliary circuit: the coil outlet of the water tank is connected to the inlet of the second water pump 12, the outlet of the second water pump 12 is connected to the inlet of the heating radiator 11, and the outlet of the heating radiator 11 is connected to the inlet coil of the water tank 13 to form a liquid circuit.

[0057] The operation process of the waste heat utilization device is as follows: when the fuel cell is running, it generates heat and electric energy, and the heat of the fuel cell is taken away by the coolant. The heat is dissipated through the heat exchanger 2 and the auxiliary radiator 3; further, the auxiliary radiator 3 is an air-cooled radiator, and the heat exchanger 2 is a water-cooled radiator.

[0058] The heat exchanger 2 is specifically provided with 5 ports, two ports at the hot end, one inlet and one outlet, and the coolant flows through the fuel cell stack. The other three ports connected to the external circuit are two inlets and one outlet. The main function is to exchange the heat of the fuel cell to the external circuit. The external circuit part has two inlets and one outlet. Under the action of the water pump, the peripheral coolant enters the user's heating circuit and hot water circuit respectively through the electric control valve.

[0059] According to the hot water temperature demand of the water tank and the temperature of the user's room, the electric control valve distributes the flow to the water tank and the heating device, thereby controlling the heat entering the water tank and the room, thereby achieving temperature control of the water tank and the room.

[0060] The heating auxiliary circuit is an auxiliary heating device that mainly solves two problems:

[0061] First, when the fuel cell stack is not in operation, that is, the demand for electricity is relatively small, but there is a need for heating in winter, and heat needs to be exchanged from the heat storage water tank; second, when the operating power of the fuel cell stack is relatively small, the actual thermal power of the stack is less than the heat demand. This is mainly based on the matching problem of user electricity consumption and usage. That is, when the heat of the stack is not enough, the heat of the water storage tank can be exchanged for the heating heat dissipation device 11; as an auxiliary heating heat supplement system, by exchanging heat with the heat in the water tank, the heat of the water tank is transferred through the coil, and under the action of the second water pump 12, it is transferred to the heating device, and heat is exchanged with the air in the room, and finally flows back to the heat exchange water storage tank 13; further, the heat exchange water storage tank 13 is a water tank with a coil, which has two coils. The heat exchange fluid in the tube is heat-exchanged through the coil in the water tank and flows through the water tank for heat exchange.

[0062] like Figure 2-5 , the overall logic diagram of the control method of the fuel cell cogeneration waste heat utilization system, the specific control method or process is as follows:

[0063] After the fuel cell system is powered on, the temperature is monitored in sequence, specifically through the water tank temperature sensor, indoor temperature sensor, and outdoor temperature sensor; the controller integrates the sensor data and performs logical judgment and control operations. After the monitoring is completed, the equipment enters the waste heat utilization control process.

[0064] Monitor whether the fuel cell load has electricity demand. If it is detected that the load has electricity demand, the waste heat control logic is started and the water tank temperature monitoring logic is entered; if it is detected that there is no electricity demand, the fuel cell system enters the standby mode, monitors the electricity demand and status, and enters the water tank temperature monitoring logic;

[0065] In case of electricity demand:

[0066] like Figure 3 , when the water tank temperature and the indoor temperature are greater than the set temperature, for example, the water tank temperature Tw>45°C and the indoor temperature Tr>16°C, the residual heat is sufficient, and the auxiliary radiator 3 is started to adjust the fan speed to meet the stack entry temperature;

[0067] Heating mode:

[0068] like Figure 4 , when the fuel cell system generates electricity and runs, and hot water and heating are required at the same time:

[0069] The heat exchanger 2 and the auxiliary radiator 3 are used to maintain thermal balance for the fuel cell stack, and the opening ratio of the flow to the water tank 13 and the heating and cooling device 11 is adjusted. The electric control valve 10 automatically adjusts the flow to the water tank and the heating device based on the water tank and indoor temperature, thereby controlling the heat flowing to the heating device and the water tank, and further controlling the reasonable distribution of waste heat during the operation of the fuel cell stack, maintaining the indoor temperature and the water tank temperature within the set range.

[0070] For example, when the water tank temperature, outdoor temperature, and indoor temperature are lower than the set temperature, for example: the water tank temperature Tw is less than 45°C, the outdoor temperature To is less than 16°C, and the indoor temperature Tr is less than 21°C, the heating mode is entered, and the electric control valve 10 is opened to the heating heat dissipation device 11 and the heat exchanger and heat storage tank 13 at the same time, and the valve opening is adjusted. The valve opening range is 1%-99%, preferably 20%-80%. The opening size is determined by the indoor temperature. When the indoor temperature is low (less than 16°C), the valve opening tends to the heating device opening of 80%. When the room temperature is close to 21°C, the valve opening gradually decreases to 20%, reducing the heating intensity, maintaining the heating temperature, and entering the water tank heat storage mode.

[0071] Furthermore, when the fuel cell system generates electricity and does not require heating, but only needs to supply hot water:

[0072] During the operation of the fuel cell, the temperature balance of the fuel cell stack 1 is maintained through the radiator 2 and the radiator 3. The opening of the electric control valve 10 facing the heater is closed, and heat is exchanged with the heat exchange water storage tank 13. At the same time, based on the temperature in the cooling circuit of the fuel cell system, the auxiliary radiator 3 is started or closed to maintain the temperature balance of the fuel cell stack.

[0073] When the fuel cell system is not generating electricity and hot water and heating are required at the same time:

[0074] At this time, the fuel cell system is not running and no additional waste heat is generated. In order to maintain the temperature of the indoor heating, the heating auxiliary circuit is started. Through the second second water pump 12, the heat exchange fluid in the heating auxiliary circuit flows through the coil of the water tank, absorbs the heat in the water tank, and maintains the heat in the indoor heating;

[0075] When the fuel cell system is not running and the water tank temperature does not reach the set temperature (the controller detects this state), the controller sends a signal to the smart switch, the smart switch turns on, the water tank is powered by the energy storage battery, and the heating is started to maintain the temperature of the water tank and the heating device.

[0076] like Figure 5 , when there is no electricity demand:

[0077] When there is no demand for electricity, and the water tank temperature is greater than the set temperature, and the indoor temperature and outdoor temperature are less than the set temperature, for example, Tw>45℃, To<16℃, Tr<21℃, then the second water pump 12 is turned on, and the heat stored in the water tank is exchanged for heating to maintain the room temperature; if there is no demand for electricity, no load is started, the water tank temperature Tw<45℃, the smart switch 8 is turned on, the lithium battery supplies power to the water tank, and the water tank heating is started; when the lithium battery SOC is less than 30%, a power request is sent to the fuel cell system to start a new round of logical judgment.

[0078] Beneficial Effects

[0079] The fuel cell cogeneration system is characterized in that the waste heat utilization device can provide a continuous and stable heat source and electric energy, while ensuring the stable operation of the fuel cell 1. According to user needs, the heat exchange fluid flow is adjusted by the thermostat to automatically distribute the waste heat of the fuel cell; the heat exchanged by the heat exchange water tank is distributed to the heating device according to the usage scenario; the distribution of the waste heat of the fuel cell and the stable supply of heat are controlled, while the fuel utilization rate is improved and the load on the electricity and the stack is reduced. The indoor temperature of the heating room and the hot water temperature can be intelligently adjusted according to user needs. Accurate control of the user-side temperature and efficient utilization of waste heat are achieved, and the stability of the stack inlet temperature and the user's dynamic heat temperature is achieved.

[0080] Through dynamic logic control, the optimal design parameters and operating parameters are obtained, such as the optimal speed of each water pump, the opening state of the electric control valve, the start and stop of the intelligent switch, etc. Based on the changes in the water temperature of the hot water storage tank and the indoor heating temperature and the user's electricity demand, the thermostatic valve is controlled to control the distribution of the flow out of the heat exchanger, which flows to the hot water supply system and the heating supply system respectively. The flow rate of the water tank and the heating out of the heat exchanger determines the amount of heat given to the water tank for heat exchange and the amount of heat given to the heating, thereby controlling the temperature of the water tank and the heating. In order to ensure the stable operation of the user's heating, the second water pump 12 is turned on and off in real time according to the indoor temperature changes and the operating state of the fuel cell system through the hot water tank connection, and the heat of the water tank is exchanged to the heating, supplementing the heat when the fuel cell waste heat is insufficient, so that the indoor heating temperature remains stable. This control method maximizes the utilization of waste heat while maintaining user comfort, that is, the room temperature and hot water temperature are within the set range.

[0081] The optimal distribution of waste heat is achieved through dynamic logic judgment. Combined with the opening of the electronically controlled valve, room temperature adjustment and water tank temperature management, the waste heat utilization efficiency and the dynamic operation of the system are improved, ensuring the stability of the fuel cell system's stack temperature and the stability of heat use at the user end.

[0082] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fuel cell waste heat utilization system, characterized in that: include: A fuel cell stack (1), a stack heat balance device, an energy storage device, and a waste heat utilization device, wherein: The fuel cell stack is provided with an inlet and an outlet; The stack thermal balance device comprises: a water pump (4), a stack outlet temperature sensor (5), a stack inlet temperature sensor (6), a heat exchanger (2), and an auxiliary radiator (3). The coolant flows through the fuel cell stack through the heat exchanger (2) and the auxiliary radiator (3) to maintain the thermal balance of the stack. The heat exchanger (2) comprises a hot end and a cold end; the hot end is provided with an inlet and an outlet; the cold end is provided with two inlets and one outlet; The energy storage device comprises an energy storage lithium battery (7) and a control switch (8); The waste heat utilization device comprises: a first water pump (9), an electric control valve (10), a heating and cooling device (11), a second water pump (12), and a heat exchange and hot water storage tank (13); The outlet of the heat exchanger (2) is connected to the first water pump (9), and the outlet of the first water pump (9) is connected to the inlet of the electric control valve (10); the outlet of the electric control valve is connected to the heat exchange water storage tank (13), and the heat exchange water storage tank (13) is connected to the inlet of the cold end of the heat exchanger (2), so as to form a user hot water circuit; The outlet of the electric control valve (10) is connected to the inlet of the heating and radiating device (11), and the outlet of the heating and radiating device (11) is connected to the inlet of the cold end of the heat exchanger (2), so as to form a user heating circuit; the outlet of the heat exchange water storage tank (13) is connected to the inlet of the second water pump (12), and the outlet of the second water pump (12) is connected to the inlet of the heating and radiating device (11), and the outlet of the heating and radiating device (11) is connected to the inlet of the heat exchange water storage tank (13), so as to form a heating auxiliary circuit.

2. A fuel cell waste heat utilization system according to claim 1, characterized in that: The heat exchange water storage tank (13) is provided with two coils, and the heat exchange fluid in the tubes is exchanged through the coils in the water tank.

3. A fuel cell waste heat utilization system according to claim 1, characterized in that: The water pump (9) is an electronic water pump, and the flow rate to the heat exchange water storage tank (13) and the heating device is adjusted by controlling the flow rate of the water pump.

4. A fuel cell waste heat utilization system according to claim 1, characterized in that: The electric control valve (10) regulates the distribution of fluid flow and can adjust the angle of the valve to close or open the direction of the flow toward the heating and cooling device (11).

5. A fuel cell waste heat utilization system according to claim 1, characterized in that: The second water pump (12) is an electronic water pump, which is used to control the liquid flow in the auxiliary heating circuit and thus control the heating temperature.

6. A control method for a fuel cell waste heat utilization system, characterized in that: The steps include: Step 1: Fuel cell voltage establishment; Step 2: Monitor whether the fuel cell load has power demand, if yes, proceed to step 3; If not, when the water temperature of the heat exchange water storage tank (13) is monitored to be lower than the set temperature, the control switch (8) is activated and the energy storage lithium battery (7) generates electricity; If it is detected that the water temperature of the heat exchange water storage tank (13) is greater than the set temperature and the outdoor temperature and indoor temperature are less than the set temperature, the second water pump (12) is turned on to supply heat to the room; Step 3: If it is detected that the water temperature of the heat exchange water storage tank (13), the outdoor temperature, and the indoor temperature are all lower than the set temperature, the electric control valve (10) is opened to control the flow to the heat exchange water storage tank (13) and the heating and cooling device (11), and the auxiliary radiator (3) is closed; If it is monitored that the water temperature of the heat exchange water storage tank (13) is lower than the set temperature, and the outdoor temperature and the indoor temperature are higher than the set temperature, the electric control valve (10) opens to the heat exchange water storage tank; If it is monitored that the water temperature of the heat exchange water storage tank (13) is greater than the set temperature and the indoor temperature is lower than the set temperature, the electric control valve (10) opens to the heating and cooling device; As in the above steps, if the stacking temperature is higher than the set stacking temperature, the auxiliary radiator (3) is started; If it is monitored that the water temperature of the heat exchange water storage tank (13) and the indoor temperature are greater than the set temperature, the auxiliary radiator (3) is started.

7. The control method of a fuel cell waste heat utilization system according to claim 6, characterized in that: The fuel cell stack (1) entry temperature and exit temperature are controlled within a target temperature range by controlling the rotation speed of the first water pump (9) and the fan rotation speed of the auxiliary radiator (3); when the waste heat utilization demand is greater than or equal to the fuel cell heat dissipation demand, the radiator fan is turned off; when the waste heat utilization demand is less than the fuel cell heat dissipation demand, the radiator fan is started based on the temperature of the entry temperature sensor (6) to reach the target rotation speed, so that the entry temperature is within the target temperature range.

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