A system and method for combined heat and power

Abstract

This invention discloses a combined heat and power (CHP) system and method. The system includes a fuel cell stack, a hydrogen supply unit, an air supply unit, a converter, a medium-temperature cooling circuit, and a heat pump coupling unit. The hydrogen supply unit and the air supply unit supply hydrogen and oxygen-containing air to the fuel cell stack, respectively. The fuel cell stack converts the hydrogen and oxygen-containing air into electrical energy, water, and heat, and then transfers the electrical energy to electrical load equipment via the converter. The medium-temperature cooling circuit draws medium-temperature coolant from the fuel cell stack to the heat exchanger, whereby the heat is transferred to a first heat load device. The heat pump coupling unit heats the heat discharged from the heat exchanger, transferring the heated heat to a second heat load device. The second heat load device requires heat at a temperature higher than that required by the first heat load device. Using this invention, energy utilization efficiency can be effectively improved while meeting diverse heat load demands.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more particularly to a system and method for combined heat and power (CHP). Background Technology

[0002] Fuel cells are highly efficient and clean energy conversion devices with advantages of high efficiency and low pollution, and are currently receiving widespread attention in distributed power generation and combined heat and power (CHP) technologies. During operation, fuel cells generate not only electricity but also a significant amount of waste heat. Therefore, to effectively recover and utilize this waste heat and improve the overall energy efficiency of the system, existing technologies offer a CHP system based on a fuel cell stack to recover the heat generated by the fuel cell stack while simultaneously providing both electricity and heat, thereby significantly improving energy utilization efficiency.

[0003] The cogeneration systems used in the prior art typically include a heat recovery unit, which consists of a coolant loop for the fuel cell stack, a heat exchanger, and a heat recovery loop. The cogeneration system mainly removes the heat generated by the fuel cell stack by circulating coolant, then transfers the heat to water through the heat exchanger, and finally meets part of the heat load demand by providing hot water.

[0004] However, in existing combined heat and power (CHP) systems, the low-temperature heat output temperature provided by the CHP system is usually between 60-80°C. For applications requiring higher temperature heat sources (such as industrial steam and high-temperature heating), the heat energy grade is relatively low, making it difficult for the recovered heat energy to meet different heat load demands. At the same time, when the heat load demand is insufficient or the return water temperature is high, the waste heat from the fuel cell is difficult to dissipate in time and must be discharged into the environment through the radiator, resulting in a waste of usable heat energy and low energy utilization.

[0005] Therefore, how to effectively improve the energy utilization rate of combined heat and power systems while meeting different heat load demands is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a combined heat and power (CHP) system and method to solve the technical problems of failing to meet different heat load demands and low energy utilization.

[0007] In a first aspect, to achieve the above objectives, embodiments of the present invention provide a combined heat and power system, comprising: a fuel cell stack, a hydrogen supply unit, an air supply unit, a converter, a medium-temperature cooling circuit, and a heat pump coupling unit; The hydrogen supply unit and the air supply unit are respectively used to supply hydrogen and oxygen-containing air to the fuel cell stack; The fuel cell stack is used to convert the hydrogen and oxygen-containing air into electrical energy, water and heat through an electrochemical reaction, and to transfer the electrical energy to electrical load equipment through the converter; The intermediate-temperature cooling circuit is connected to the fuel cell stack and the heat pump coupling unit respectively. The intermediate-temperature cooling circuit is used to draw intermediate-temperature coolant from the fuel cell stack to the heat exchanger, so as to transfer the heat carried by the intermediate-temperature coolant to the first heat load device through the heat exchanger, and reintroduce the low-temperature coolant after heat transfer into the fuel cell stack. The heat pump coupling unit is used to heat the heat discharged by the heat exchanger so as to transfer the heated heat to the second heat load device. The temperature of the heat required by the second heat load device is greater than the temperature of the heat required by the first heat load device.

[0008] In some embodiments, the combined heat and power system further includes a coordination and control unit; The coordination and control unit is used to receive operating data from the fuel cell stack, the hydrogen supply unit, the air supply unit, the converter, the intermediate temperature cooling circuit, the heat pump coupling unit, the electrical load equipment, the first heat load equipment, and the second heat load equipment, and to generate control commands based on the operating data to control any component in the combined heat and power system to operate.

[0009] In some embodiments, the operating data of the fuel cell stack includes the outlet temperature of the coolant outlet, and the operating data of the second heat load device includes the target required temperature; The coordination and control unit is also used to switch to direct supply mode when the outlet temperature is not lower than the target required temperature, so as to control the heat pump coupling unit to perform a shutdown operation and maintain the outlet temperature; The coordination control unit is also used to switch to coupling mode when the outlet temperature is lower than the target required temperature, so as to control the heat pump coupling unit to perform a heating operation and raise the temperature of the heat flowing through the heat pump coupling unit to the target required temperature.

[0010] In some embodiments, the heat pump coupling unit includes a compressor and a condenser, and the operating data of the heat pump coupling unit includes the operating frequency of the compressor and the outlet water temperature of the condenser outlet. When switching to the coupling mode, the coordination control unit is specifically used to determine the temperature difference that needs to be heated based on the target required temperature and the outlet water temperature, and to determine the operating frequency of the compressor based on the temperature difference.

[0011] In some embodiments, the operating data of the fuel cell stack also includes output current; The coordination and control unit is further configured to correct the operating frequency according to the rate of change of the output current to obtain the target operating frequency of the compressor, and control the compressor to work according to the target frequency.

[0012] In some embodiments, the operating data of the fuel cell stack also includes the inlet temperature of the coolant inlet; After determining the target frequency, the coordination control unit is further configured to control the compressor to reduce its operating frequency and, at the same time, control the medium-temperature cooling circuit to increase the flow rate of the coolant when the inlet temperature is less than a preset safety threshold temperature.

[0013] In some embodiments, the heat pump coupling unit further includes an auxiliary electric heater; The coordination control unit is further configured to control the auxiliary electric heater to raise the temperature of the heat pump coupling unit to the target required temperature when the compressor is operating at its maximum operating frequency and the outlet water temperature is still lower than the target required temperature.

[0014] In some embodiments, the heat pump coupling unit may also be directly connected to the fuel cell stack, and the heat pump coupling unit is also used to heat up the heat carried by the intermediate-temperature coolant flowing out of the fuel cell stack, so as to transfer the heated heat to the second heat load device.

[0015] In some embodiments, the combined heat and power system further includes a circulation pump connected to the intermediate temperature cooling circuit and the heat pump coupling unit, respectively. The circulation pump is used to reintroduce the cryogenic coolant that has undergone heat exchange in the intermediate temperature cooling circuit and the heat pump coupling unit into the fuel cell stack.

[0016] In a second aspect, to solve the same technical problem, embodiments of the present invention provide a method for combined heat and power (CHP), applied to the CHP system described in any of the above embodiments. The CHP system includes: a fuel cell stack, a hydrogen supply unit, an air supply unit, a converter, a medium-temperature cooling circuit, and a heat pump coupling unit. The method includes the following steps: The hydrogen supply unit and the air supply unit respectively supply hydrogen and oxygen-containing air to the fuel cell stack; The fuel cell stack converts hydrogen and oxygen-containing air into electrical energy, water, and heat through an electrochemical reaction, and the converter transfers the electrical energy to electrical load equipment. The intermediate-temperature cooling circuit leads the intermediate-temperature coolant from the fuel cell stack to the heat exchanger, so as to transfer the heat carried by the intermediate-temperature coolant to the first heat load device through the heat exchanger, and reintroduce the low-temperature coolant after heat transfer into the fuel cell stack. The heat pump coupling unit heats up the heat discharged from the heat exchanger to transfer the heated heat to the second heat load device. The second heat load device requires a higher temperature of heat than the first heat load device.

[0017] This invention provides a combined heat and power (CHP) system and method. A converter transfers electrical energy generated by a fuel cell stack to an electrical load device. A heat exchanger transfers heat from the medium-temperature coolant drawn from the fuel cell stack through a cooling loop to a first heat load device. A heat pump coupling unit heats the heat discharged from the heat exchanger and transfers the heated heat to a second heat load device. This system efficiently utilizes the waste heat from the fuel cell stack in stages to provide heat output of different grades, thereby effectively improving energy efficiency while meeting diverse heat load demands. Attached Figure Description

[0018] Figure 1a This is a schematic diagram of a combined heat and power system provided in an embodiment of the present invention; Figure 1b This is another structural schematic diagram of the combined heat and power system provided in the embodiment of the present invention; Figure 2 This is a schematic flowchart of a combined heat and power system operation strategy provided in an embodiment of the present invention; Figure 3 This is a schematic flowchart of a combined heat and power method provided in an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be understood that the steps described in the method embodiments of this disclosure may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this disclosure is not limited in this respect.

[0021] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0022] Among related technologies, fuel cells are highly efficient and clean energy conversion devices with advantages of high efficiency and low pollution, and are currently receiving widespread attention in distributed power generation and combined heat and power (CHP) technologies. During operation, fuel cells generate not only electricity but also a large amount of waste heat. Therefore, in order to effectively recover and utilize this waste heat and improve the overall energy utilization efficiency of the system, existing technologies provide a CHP system based on a fuel cell stack to recover the heat generated by the fuel cell stack while simultaneously providing electricity and heat, thereby significantly improving energy utilization efficiency.

[0023] The cogeneration systems used in the prior art typically include a heat recovery unit, which consists of a coolant loop for the fuel cell stack, a heat exchanger, and a heat recovery loop. The cogeneration system mainly removes the heat generated by the fuel cell stack by circulating coolant, then transfers the heat to water through the heat exchanger, and finally meets part of the heat load demand by providing hot water.

[0024] However, in existing combined heat and power (CHP) systems, the low-temperature heat output temperature provided by the CHP system is usually between 60-80°C. For applications requiring higher temperature heat sources (such as industrial steam and high-temperature heating), the heat energy grade is relatively low, making it difficult for the recovered heat energy to meet different heat load demands. At the same time, when the heat load demand is insufficient or the return water temperature is high, the waste heat from the fuel cell is difficult to dissipate in time and must be discharged into the environment through the radiator, resulting in a waste of usable heat energy and low energy utilization.

[0025] Therefore, how to effectively improve the energy utilization rate of combined heat and power systems while meeting different heat load demands is a technical problem that urgently needs to be solved.

[0026] To address the technical problems existing in related technologies, this embodiment provides a combined heat and power system. Please refer to [link / reference]. Figure 1a , Figure 1a This is a schematic diagram of a combined heat and power system provided in an embodiment of the present invention, such as... Figure 1a As shown, the combined heat and power system provided in this embodiment of the invention includes: a fuel cell stack, a hydrogen supply unit, an air supply unit, a converter, a medium-temperature cooling circuit, and a heat pump coupling unit; The hydrogen supply unit and the air supply unit are used to supply hydrogen and oxygen-containing air to the fuel cell stack, respectively. The fuel cell stack is used to convert the hydrogen and oxygen-containing air into electrical energy, water, and heat through an electrochemical reaction, and to transfer the electrical energy to the electrical load device through the converter. The intermediate-temperature cooling circuit is connected to the fuel cell stack and the heat pump coupling unit. The intermediate-temperature cooling circuit is used to draw intermediate-temperature coolant from the fuel cell stack to a heat exchanger, so that the heat carried by the intermediate-temperature coolant can be transferred to the first heat load device through the heat exchanger, and the low-temperature coolant after heat transfer can be reintroduced into the fuel cell stack. The heat pump coupling unit is used to heat the heat discharged from the heat exchanger, so that the heated heat can be transferred to the second heat load device, the temperature of the heat required by the second heat load device is greater than the temperature of the heat required by the first heat load device.

[0027] In this embodiment, the hydrogen supply unit must ensure that the purity of the supplied hydrogen meets the operating requirements of the fuel cell stack. The air supply unit must not only provide sufficient oxygen, but also filter, humidify, and regulate the temperature of the air entering the fuel cell stack to achieve optimal reaction conditions. The converter is mainly used to convert the DC power output from the fuel cell stack into AC power that meets the requirements of the electrical load equipment. Specifically, the converter can be a DC / AC converter, a current sensor, etc., and the electrical load equipment can include the power grid or local loads. The intermediate temperature cooling circuit is mainly used to control the temperature of the fuel cell stack to ensure that it operates stably within a suitable operating temperature range. This circuit can remove the heat generated by the fuel cell stack through the circulation of coolant and transfer the heat to the first heat load equipment through a heat exchanger.

[0028] The heat pump coupling unit is mainly used to upgrade the quality of low-grade heat discharged from the heat exchanger; specifically, for example... Figure 1a As shown, the heat pump coupling unit may include a heat pump system, which can drive the compressor to operate by consuming a small amount of electrical energy. The working fluid in the heat pump system absorbs the heat discharged from the heat exchanger in the evaporator, and then is compressed and heated in the compressor. The heated heat is then introduced into the condenser to exchange heat with the circulating medium of the second heat load equipment, thereby transferring the heated heat to the second heat load equipment and realizing the heating and utilization of heat.

[0029] In a heat pump system, the working fluid undergoes phase change and circulates among components such as the evaporator, compressor, condenser, and expansion valve, thereby transferring heat from a low-temperature heat source to a high-temperature heat source. Specifically, the evaporator of the heat pump coupling unit absorbs heat discharged from the heat exchanger, causing the working fluid to evaporate into a gaseous state. The gaseous working fluid then enters the compressor, where it is compressed, heated, and pressurized. It then enters the condenser to exchange heat with the coolant requiring heating, releasing heat and condensing into a liquid state. The liquid working fluid passes through the expansion valve to reduce its pressure and temperature before returning to the evaporator, completing one cycle. Through this cyclical process, the heat pump coupling unit can raise the temperature of low-grade heat that is difficult to utilize directly to the high temperature required by the secondary heat load equipment. For example, it can raise the temperature from 60-80°C to over 100°C, meeting the steam demand in industrial production or high-temperature heating scenarios.

[0030] In this embodiment, the coolant provided can be a medium with good thermal conductivity, such as deionized water or a specific antifreeze. The flow rate and temperature of the coolant in the fuel cell stack can be dynamically adjusted according to the real-time heating of the fuel cell stack to ensure that the fuel cell stack operates within a suitable temperature range. Specifically, in this embodiment, the flow rate of the coolant in the fuel cell stack can be adjusted by a valve.

[0031] It should be noted that the first heat load device provided in this embodiment may include domestic hot water supply system, floor heating system and other heat-using equipment with relatively low temperature requirements, while the second heat load device may cover scenarios that require higher temperature heat energy, such as steam generator and high temperature drying equipment in industrial production. Through this graded heating method, the heat generated by the fuel cell stack can be used in a graded manner, avoiding energy waste when using a single heat load.

[0032] Thus, the combined heat and power system provided in this embodiment of the invention can transfer the electrical energy generated by the fuel cell stack to the electrical load device through the converter, transfer the heat of the medium-temperature coolant drawn from the fuel cell stack through the heat exchanger to the first heat load device through the heat cooling circuit, and heat the heat discharged from the heat exchanger through the heat pump coupling unit to transfer the heated heat to the second heat load device. It can efficiently utilize the waste heat of the fuel cell stack in stages to provide heat energy output of different grades, thereby achieving the goal of effectively improving energy utilization while meeting diverse heat load requirements.

[0033] In some embodiments, please continue to see Figure 1aThe combined heat and power system provided in this embodiment may further include a coordination and control unit. The coordination and control unit may be used to receive the operating data of the fuel cell stack, the hydrogen supply unit, the air supply unit, the converter, the intermediate temperature cooling circuit, the heat pump coupling unit, the electrical load equipment, the first heat load equipment, and the second heat load equipment, and generate control commands for controlling any component in the combined heat and power system to operate based on the operating data.

[0034] The coordination and control unit can be a terminal device, such as an industrial control computer, PLC controller, or embedded microprocessor, which integrates a data analysis module and an instruction generation module. The data analysis module processes the collected data, analyzes the current operating status of the system, and determines whether the operating parameters of each component need adjustment. The instruction generation module generates corresponding control instructions based on the analysis results and sends them to each execution component through a communication interface, achieving dynamic coordinated control of the entire combined heat and power system. This ensures that the system operates efficiently and stably under different operating conditions, further optimizing energy utilization efficiency and meeting the dynamic demands of various loads.

[0035] The components in the combined heat and power (CHP) system refer to any one of the following: the fuel cell stack, the hydrogen supply unit, the air supply unit, the converter, the intermediate-temperature cooling circuit, and the heat pump coupling unit. Simultaneously, the operational data of each component can be collected using sensors installed in the system, such as temperature sensors, pressure sensors, and flow sensors. These sensors monitor key parameters such as the operating temperature of the fuel cell stack, the supply pressure and flow rate of hydrogen and air, the temperature and flow rate of the coolant, the power demand of the electrical load equipment, and the real-time heat demand of the thermal load equipment.

[0036] Thus, by coordinating and controlling the real-time monitoring of the operational data of each component in the system, the control commands can be dynamically adjusted according to the actual changes in the demand of the electrical load equipment, the first heat load equipment, and the second heat load equipment, achieving intelligent coordinated management of the entire combined heat and power system. For example, when the electrical load demand suddenly increases, the coordinating and controlling control unit can control the hydrogen supply unit and the air supply unit to increase the supply of hydrogen and oxygen-containing air accordingly, ensuring that the fuel cell stack outputs more electrical energy; if the heat demand of the first heat load equipment decreases, the coordinating and controlling control unit can adjust the flow rate of the intermediate temperature cooling circuit or the operating state of the heat exchanger to avoid excessive heat transfer and waste, or optimize the operating parameters of the heat pump coupling unit to ensure that it can efficiently heat the waste heat discharged from the heat exchanger to meet the demand of the second heat load equipment, thereby further improving the overall operating efficiency of the system and the flexibility of energy utilization.

[0037] In some embodiments, the operating data of the fuel cell stack provided in this embodiment may include the outlet temperature of the coolant outlet, and the operating data of the second heat load device may include the target required temperature. In this case, in order to reduce unnecessary energy waste, the coordination control unit may also be used to switch to direct supply mode when the outlet temperature is not lower than the target required temperature, so as to control the heat pump coupling unit to perform a shutdown operation and maintain the outlet temperature; and to switch to coupling mode when the outlet temperature is lower than the target required temperature, so as to control the heat pump coupling unit to perform a heating operation and raise the temperature of the heat flowing through the heat pump coupling unit to the target required temperature.

[0038] Thus, by coordinating the control unit to dynamically select the most economical and efficient heat supply method based on the real-time comparison between the fuel cell stack coolant outlet temperature and the target temperature requirement of the second heat load equipment, the system directly shuts down the heat pump coupling unit when the outlet temperature is sufficient to meet the high-temperature requirements of the second heat load equipment, utilizing the coolant's own heat for direct supply, avoiding electrical energy consumption during heat pump operation, and further reducing system energy consumption. Conversely, when the outlet temperature is lower than the target temperature requirement, the heat pump coupling unit is promptly activated to raise the temperature, ensuring a stable and reliable heat supply to the second heat load equipment. This maximizes the system's energy utilization efficiency while ensuring heat load requirements are met. This adaptive adjustment of the operating mode based on actual operating conditions effectively balances the matching relationship between energy supply and demand, improving the system's economic efficiency and reliability.

[0039] like Figure 1a As shown, the heat pump coupling unit provided in this embodiment may include a compressor and a condenser. The operating data of the heat pump coupling unit includes the operating frequency of the compressor and the outlet water temperature of the condenser. The operating data of the fuel cell stack also includes the output current. When switching to the coupling mode, the coordination control unit can specifically determine the temperature difference requiring heating based on the target required temperature and the outlet water temperature, and determine the operating frequency of the compressor based on the temperature difference. Simultaneously, the coordination control unit is also specifically used to correct the operating frequency according to the rate of change of the output current to obtain the target operating frequency of the compressor, and control the compressor to operate according to the target frequency.

[0040] Thus, in order to ensure that the heat pump coupling unit can accurately heat the heat discharged from the heat exchanger to the target temperature required by the second heat load equipment, the coordination control unit can dynamically adjust the operating frequency of the compressor in the heat pump system according to the difference between the outlet temperature and the target temperature. It can also pre-adjust the operating parameters of the heat pump coupling unit in advance based on the real-time heat demand changes of the second heat load equipment. This can avoid unstable temperature supply caused by demand fluctuations, further ensure the system's accurate control of high-grade heat energy output, and reduce the power consumption generated by the additional operation of the heat pump.

[0041] In this embodiment, the operating frequency of the heat pump compressor can be calculated using an adaptive PID algorithm. This involves combining proportional (P), integral (I), and derivative (D) components to dynamically adjust the output control quantity based on the deviation between the target required temperature and the actual outlet water temperature, thereby achieving precise regulation of the compressor's operating frequency. Thus, through PID algorithm control, the heat pump coupling unit can operate stably and efficiently under different operating conditions, ensuring that the temperature requirements of the secondary heat load equipment are accurately met, while minimizing compressor energy consumption and improving the energy utilization efficiency and operational stability of the entire combined heat and power system.

[0042] As an optional embodiment, to further improve the operational stability of the combined heat and power system provided in this embodiment, this embodiment also needs to perform cold shock assessment on the fuel cell stack to avoid damage to its internal components due to sudden temperature rises and falls caused by excessively low coolant temperatures during fuel cell stack operation. Specifically, cold shock can be determined by monitoring the temperature of the coolant entering the fuel cell stack: when the coolant temperature is not lower than a preset safety threshold temperature (e.g., 5°C), it can be determined that there is no risk of cold shock, and the compressor can be directly controlled to operate at the target frequency; when the coolant temperature is lower than the preset safety threshold temperature, it can be determined that there is a risk of cold shock, and the operating frequency of the compressor can be limited by coordinating the control unit to ensure that the inlet temperature rises to the safe range, i.e., the preset threshold.

[0043] Therefore, the operating data of the fuel cell stack provided in this embodiment may further include the inlet temperature of the coolant inlet. After determining the target frequency, the coordination control unit is further configured to control the compressor to reduce its operating frequency and simultaneously control the medium-temperature cooling circuit to increase the coolant flow rate when the inlet temperature is lower than a preset safety threshold temperature. Thus, by employing the embodiment provided by this invention, the long-term stable operation of the entire combined heat and power system can be ensured.

[0044] In some embodiments, to ensure that the heat demand of the second heat load device can be met, the heat pump coupling unit may further include an auxiliary electric heater. In this case, this embodiment can monitor the relationship between the outlet water temperature of the condenser and the target required temperature in real time when the heat pump is operating at its maximum frequency, which is the frequency without cold shock. In order to control the auxiliary electric heater to raise the heat flowing through the heat pump coupling unit to the target required temperature when the compressor is operating at its maximum frequency and the outlet water temperature is still lower than the target required temperature.

[0045] Thus, through the coordinated heat compensation of the auxiliary electric heater, the heat gap can be quickly filled when the heat pump system, even at its maximum heating capacity, is still insufficient to meet the high-temperature demand of the second heat load equipment, ensuring the continuity and stability of high-temperature heat energy supply. Specifically, when the compressor in the heat pump coupling unit is operating at its maximum frequency, and the condenser outlet water temperature is still detected to be lower than the target temperature required by the second heat load equipment, the coordination control unit will immediately trigger the auxiliary electric heater to start, using electrical energy to directly reheat the circulating medium after it has been heated by the heat pump coupling unit until its temperature reaches the target value.

[0046] Optional, please continue to see Figure 1a The auxiliary electric heater provided in this embodiment can be placed before the heat pump coupling unit, between the heat pump coupling unit and the second heat load device, or simultaneously before and between the heat pump coupling unit and the second heat load device. When the auxiliary electric heater is placed before the heat pump coupling unit, it can preheat the low-grade heat entering the heat pump system, increasing the evaporation temperature of the heat pump system and indirectly improving the heating efficiency of the heat pump. If placed between the heat pump coupling unit and the second heat load device, it can directly and precisely supplement the heat output by the heat pump, ensuring that the temperature of the medium finally entering the second heat load device strictly meets the standards. Simultaneously setting two auxiliary electric heaters further enhances the system's heat supply capacity under high loads or low heat source temperatures, ensuring that the second heat load device can obtain stable and reliable high-temperature heat energy under any operating conditions, avoiding heat supply interruptions due to insufficient capacity of a single heat pump system, and further improving the reliability and stability of the entire combined heat and power system.

[0047] Meanwhile, the activation of the auxiliary electric heater can be precisely controlled by the coordination control unit, and it can be put into operation only when necessary, thereby minimizing additional power consumption and maintaining the overall energy efficiency of the system while ensuring heating demand.

[0048] In other embodiments, the combined heat and power system provided in this embodiment may further include a circulation pump, which can be connected to both the intermediate-temperature cooling circuit and the heat pump coupling unit, for reintroducing the cryogenic coolant, after heat exchange in the intermediate-temperature cooling circuit and the heat pump coupling unit, into the fuel cell stack. For details, please refer to... Figure 1b , Figure 1b This is another structural schematic diagram of the combined heat and power system provided in the embodiments of the present invention, such as... Figure 1b As shown, this embodiment also provides a parallel heat pump coupled staged heat recovery system. In this system, the coolant outlet of the fuel cell stack is divided into two paths. One path is directly supplied to the first heat load device through a heat exchanger; the other path enters the evaporator of the heat pump system, and after the heat quality is improved, it is supplied to the second heat load device through the condenser side of the heat pump system. The two coolant paths merge after completing their respective heat exchange and return to the fuel cell stack via a circulation pump.

[0049] Thus, by employing the parallel heat pump coupled with staged heat recovery system provided in this embodiment, the coolant flow rate drawn from the fuel cell stack can be flexibly allocated according to the actual demand ratio of the first and second heat load devices. When the first heat load demand is high, the coolant flow rate through the heat exchanger can be increased to ensure that low-grade heat demands such as domestic hot water or underfloor heating are fully met. Conversely, when the second heat load demands higher-temperature heat energy, the valve can be adjusted to increase the coolant share entering the evaporator of the heat pump system, efficiently meeting the heat demand in scenarios such as industrial steam or high-temperature drying through the heating effect of the heat pump. This parallel structure not only avoids the limitations of fixed heat utilization priority in traditional series heat recovery but also enables dynamic allocation of coolant flow rate under different heat load conditions. This allows the heat generated by the fuel cell stack to be precisely allocated and utilized in stages according to actual demand ratios, further improving the system's adaptability to different heat loads and energy utilization efficiency.

[0050] To better illustrate the working principle of the combined heat and power system provided in this embodiment, this embodiment will use a specific example to describe the energy conversion process of the system in actual operation. For details, please refer to... Figure 2 , Figure 2 This is a flowchart illustrating a system operation strategy for combined heat and power provided in an embodiment of the present invention, such as... Figure 2 As shown, firstly, parameters can be collected during the operation of the combined heat and power system to obtain key operating parameters such as the output current of the fuel cell stack, the real-time supply flow rate of hydrogen and air, the inlet and outlet temperatures and flow rates of the coolant, the real-time power demand of the electrical load equipment, and the current heat demand of the first and second heat load equipment.

[0051] After receiving these parameters, the coordination and control unit will determine the high-temperature requirement to see if the outlet temperature is lower than the target required temperature. If the determination result is no, that is, the outlet temperature is not lower than the target required temperature, the system will automatically switch to the direct supply mode. At this time, the coordination and control unit will control the heat pump coupling unit to stop running, while maintaining the current outlet temperature of the coolant, and directly supply the heat generated by the fuel cell stack to the second heat load equipment through the medium-temperature cooling circuit. If the determination result is yes, that is, the outlet temperature is lower than the target required temperature, the system will switch to the coupling mode. The coordination and control unit will then start the heat pump coupling unit and use the operation of the compressor to heat the heat so that the heat flowing through the heat pump coupling unit reaches the target required temperature of the second heat load equipment.

[0052] During operation in coupled mode, the coordination control unit continuously monitors the operating frequency of the compressor in the heat pump coupling unit and the outlet water temperature of the condenser outlet. Combined with the output current change rate of the fuel cell stack, it dynamically corrects the operating frequency of the compressor to calculate the target frequency required for the compressor in the heat pump system, ensuring the accuracy and stability of the heat supply.

[0053] After determining the target frequency required for the compressor in the heat pump system, the inlet temperature of the coolant entering the fuel cell stack will be monitored in real time, and it will be determined whether the inlet temperature is not lower than the preset safety threshold temperature. If the inlet temperature is lower than the preset safety threshold temperature, the control unit will limit the operating frequency of the compressor and control the medium-temperature cooling circuit to increase the coolant flow rate to avoid damage to the fuel cell stack due to cold shock. If the inlet temperature is not lower than the preset safety threshold temperature, the compressor will be controlled to operate according to the calculated target frequency.

[0054] Then, in the coupling mode, the system will also monitor in real time whether the compressor has run to the maximum frequency (i.e. the maximum allowable frequency when there is no cold shock). When the compressor is running at the maximum frequency and the condenser outlet water temperature is still lower than the target required temperature, the coordination control unit will start the auxiliary electric heater to reheat the heat after it has been heated by the heat pump coupling unit until the outlet water temperature reaches the target required temperature, thereby ensuring that the high temperature requirements of the second heat load equipment are reliably met.

[0055] In this way, through such real-time parameter acquisition and dynamic control processes, the combined heat and power system can achieve coordinated management of the energy conversion process, meet different load demands, maximize energy utilization efficiency, and reduce system operating costs.

[0056] This concludes the description of the combined heat and power system provided in the embodiments of the present invention.

[0057] In some embodiments, to solve the same technical problem, this embodiment also provides a combined heat and power (CHP) method, applicable to any of the CHP systems described in the above embodiments. For details, please refer to... Figure 3 , Figure 3 This is a schematic flowchart of a combined heat and power method provided in an embodiment of the present invention, such as... Figure 3 As shown, the combined heat and power method provided in this embodiment includes steps 301-304; Step 301: The hydrogen supply unit and the air supply unit respectively supply hydrogen and oxygen-containing air to the fuel cell stack.

[0058] Step 302: The fuel cell stack converts the hydrogen and oxygen-containing air into electrical energy, water and heat through an electrochemical reaction, and the converter transmits the electrical energy to the electrical load equipment.

[0059] Step 303: The intermediate-temperature cooling circuit leads the intermediate-temperature coolant from the fuel cell stack to the heat exchanger, so as to transfer the heat carried by the intermediate-temperature coolant to the first heat load device through the heat exchanger, and reintroduce the low-temperature coolant after heat transfer into the fuel cell stack.

[0060] Step 304: The heat pump coupling unit heats up the heat discharged from the heat exchanger to transfer the heated heat to the second heat load device. The temperature of the heat required by the second heat load device is greater than the temperature of the heat required by the first heat load device.

[0061] In this embodiment, the combined heat and power (CHP) system provided may include a coordination and control unit. Therefore, the CHP method provided in this embodiment can also achieve intelligent coordinated management of various system components through the control and coordination control unit. Specifically, the coordination and control unit collects real-time operating data of key components such as the fuel cell stack, hydrogen supply unit, air supply unit, intermediate temperature cooling circuit, heat pump coupling unit, electrical load equipment, first heat load equipment, and second heat load equipment. This data includes the fuel cell stack's output current, coolant inlet and outlet temperatures, hydrogen and air supply pressure and flow rate, power requirements of the electrical load equipment, and real-time heat requirements and target temperatures of the first and second heat load equipment. Based on this collected data, the coordination and control unit can dynamically analyze the system's current operating status and the actual demands of each load, thereby generating and issuing corresponding control commands. For example, when electrical load demands change, the coordination and control unit will adjust the supply of hydrogen and air accordingly to ensure the stability of the fuel cell stack's output power.

[0062] In terms of heat load management, the coordination and control unit can flexibly switch the operating mode of the heat pump coupling unit, such as direct supply mode or coupling mode, according to the difference in demand between the first heat load equipment and the second heat load equipment, as well as the temperature of the fuel cell stack coolant. It can also precisely control the operating frequency of the compressor, the start and stop of the auxiliary electric heater, and the flow rate of the circulating pump in the heat pump coupling unit, so as to maximize the system's energy utilization efficiency and operational stability while meeting the demand of each load.

[0063] It should be noted that the specific scheme for the coordinated control of the cogeneration system through the coordination control unit can be referred to the above-mentioned embodiments of the cogeneration system, and will not be elaborated here.

[0064] Therefore, the combined heat and power method provided in this embodiment of the invention can also realize the cascade utilization of heat generated by fuel cell stacks, meet the temperature requirements of different heat load equipment, maximize energy utilization efficiency, reduce system energy consumption, and enhance system operation reliability while ensuring a stable supply of electrical and heat loads.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0066] Furthermore, it should be noted that if any directional indication (such as up, down, left, right, front, back, etc.) is involved in the embodiments of the present invention, the directional indication is only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0067] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, in the embodiments of this invention, "multiple" refers to two or more. Moreover, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0068] The foregoing has provided a detailed description of a combined heat and power system and method provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application. Moreover, those skilled in the art can make several improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered to be within the scope of protection of this invention.

Claims

1. A combined heat and power (CHP) system, characterized in that, include: Fuel cell stack, hydrogen supply unit, air supply unit, converter, intermediate temperature cooling circuit, heat pump coupling unit; The hydrogen supply unit and the air supply unit are respectively used to supply hydrogen and oxygen-containing air to the fuel cell stack; The fuel cell stack is used to convert the hydrogen and oxygen-containing air into electrical energy, water and heat through an electrochemical reaction, and to transfer the electrical energy to electrical load equipment through the converter; The intermediate-temperature cooling circuit is connected to the fuel cell stack and the heat pump coupling unit respectively. The intermediate-temperature cooling circuit is used to draw intermediate-temperature coolant from the fuel cell stack to the heat exchanger, so as to transfer the heat carried by the intermediate-temperature coolant to the first heat load device through the heat exchanger, and reintroduce the low-temperature coolant after heat transfer into the fuel cell stack. The heat pump coupling unit is used to heat the heat discharged by the heat exchanger so as to transfer the heated heat to the second heat load device. The temperature of the heat required by the second heat load device is greater than the temperature of the heat required by the first heat load device.

2. The combined heat and power system according to claim 1, characterized in that, It also includes a coordination and control unit; The coordination and control unit is used to receive operating data from the fuel cell stack, the hydrogen supply unit, the air supply unit, the converter, the intermediate temperature cooling circuit, the heat pump coupling unit, the electrical load equipment, the first heat load equipment, and the second heat load equipment, and to generate control commands based on the operating data to control any component in the combined heat and power system to operate.

3. The combined heat and power system according to claim 2, characterized in that, The operating data of the fuel cell stack includes the outlet temperature of the coolant outlet, and the operating data of the second heat load device includes the target required temperature. The coordination and control unit is also used to switch to direct supply mode when the outlet temperature is not lower than the target required temperature, so as to control the heat pump coupling unit to perform a shutdown operation and maintain the outlet temperature; The coordination control unit is also used to switch to coupling mode when the outlet temperature is lower than the target required temperature, so as to control the heat pump coupling unit to perform a heating operation and raise the temperature of the heat flowing through the heat pump coupling unit to the target required temperature.

4. The combined heat and power system according to claim 3, characterized in that, The heat pump coupling unit includes a compressor and a condenser, and the operating data of the heat pump coupling unit includes the operating frequency of the compressor and the outlet water temperature of the condenser. When switching to the coupling mode, the coordination control unit is specifically used to determine the temperature difference that needs to be heated based on the target required temperature and the outlet water temperature, and to determine the operating frequency of the compressor based on the temperature difference.

5. The combined heat and power system according to claim 4, characterized in that, The operating data of the fuel cell stack also includes the output current; The coordination and control unit is further configured to correct the operating frequency according to the rate of change of the output current to obtain the target operating frequency of the compressor, and control the compressor to work according to the target frequency.

6. The combined heat and power system according to claim 5, characterized in that, The operating data of the fuel cell stack also includes the inlet temperature of the coolant inlet; After determining the target frequency, the coordination control unit is further configured to control the compressor to reduce its operating frequency and, at the same time, control the medium-temperature cooling circuit to increase the flow rate of the coolant when the inlet temperature is less than a preset safety threshold temperature.

7. The combined heat and power system according to claim 6, characterized in that, The heat pump coupling unit also includes an auxiliary electric heater; The coordination control unit is further configured to control the auxiliary electric heater to raise the temperature of the heat pump coupling unit to the target required temperature when the compressor is operating at its maximum operating frequency and the outlet water temperature is still lower than the target required temperature.

8. The combined heat and power system according to claim 1, characterized in that, The heat pump coupling unit can also be directly connected to the fuel cell stack. The heat pump coupling unit is also used to heat up the heat carried by the medium-temperature coolant flowing out of the fuel cell stack, so as to transfer the heated heat to the second heat load device.

9. The combined heat and power system according to any one of claims 1-8, characterized in that, It also includes a circulation pump, which is connected to the intermediate temperature cooling circuit and the heat pump coupling unit respectively. The circulation pump is used to reintroduce the cryogenic coolant that has undergone heat exchange in the intermediate temperature cooling circuit and the heat pump coupling unit into the fuel cell stack.

10. A method for combined heat and power, characterized in that, A combined heat and power (CHP) system applicable to any one of claims 1-9, the CHP system comprising: a fuel cell stack, a hydrogen supply unit, an air supply unit, a converter, a medium-temperature cooling circuit, and a heat pump coupling unit, the method comprising the following steps: The hydrogen supply unit and the air supply unit respectively supply hydrogen and oxygen-containing air to the fuel cell stack; The fuel cell stack converts hydrogen and oxygen-containing air into electrical energy, water, and heat through an electrochemical reaction, and the converter transfers the electrical energy to electrical load equipment. The intermediate-temperature cooling circuit leads the intermediate-temperature coolant from the fuel cell stack to the heat exchanger, so as to transfer the heat carried by the intermediate-temperature coolant to the first heat load device through the heat exchanger, and reintroduce the low-temperature coolant after heat transfer into the fuel cell stack. The heat pump coupling unit heats up the heat discharged from the heat exchanger to transfer the heated heat to the second heat load device. The second heat load device requires a higher temperature of heat than the first heat load device.

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