Heat utilization device and fuel cell heat utilization system

Abstract

The utility model relates to heat utilization device and fuel cell heat utilization system, heat utilization device includes: heat exchanger, connects to fuel cell to receive the cooling liquid after absorbing heat, with cooling liquid carries out heat exchange to produce and exports the first gaseous heat exchange medium with first temperature and first pressure, compressor, receives the first gaseous heat exchange medium, and exports the second gaseous heat exchange medium with higher temperature and higher pressure after being compressed, expander, receives the second gaseous heat exchange medium, connects to generator to drive generator mechanically when making the second gaseous heat exchange medium expand to make generator produce second electric power, and exports third gaseous heat exchange medium, condenser liquefies third gas heat exchange medium into heat exchange medium, medium pump receives heat exchange medium and pumps heat exchange medium into heat exchanger. Thus, the utility model can improve the heat utilization efficiency and overall power generation efficiency of fuel cell, simplify heat utilization operation process and reduce cost.

Description

Technical Field

[0001] This disclosure relates to the field of fuel cells, and more specifically, to the thermal utilization of fuel cells. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is a device that converts chemical energy into electrical and thermal energy. The heat generated during its operation typically accounts for 30%-50% of the overall energy output, making it a highly efficient energy conversion technology. However, how to effectively utilize this heat and improve the overall system's energy efficiency is a crucial issue in current PEMFC applications.

[0003] Currently, the operating temperature of proton exchange membrane fuel cells is typically between 60°C and 80°C. The lower temperature limits the efficiency and range of heat utilization, which requires additional heating equipment or heat pumps, thereby increasing cost and operational complexity. This operational complexity further limits the conversion efficiency from heat to useful thermal energy.

[0004] Thermal utilization technology is still under development and faces certain technical challenges and uncertainties. Utility Model Content

[0005] To address the problems in the prior art, this application proposes an improved heat utilization device and a fuel cell heat utilization system. This improved fuel cell heat utilization system is simple to design and operate, combining a compressor and an organic Rankine cycle system to provide a higher temperature and higher pressure gaseous medium to the expander in the organic Rankine cycle system. This effectively improves the power generation efficiency of the generator connected to the organic Rankine cycle system, thereby significantly improving the overall power generation efficiency and heat utilization rate of the proton exchange membrane fuel cell.

[0006] According to one aspect of this application, a heat utilization device is provided, including a heat exchanger comprising: a heat inlet connected via a coolant circuit to an external fuel cell that generates first electricity and heat through an electrochemical reaction, for receiving coolant after absorbing heat from the fuel cell; a heat exchange medium for exchanging heat with the coolant to absorb heat from the coolant to generate a gaseous heat exchange medium having a first temperature and a first pressure; and a first outlet for outputting the gaseous heat exchange medium having the first temperature and the first pressure; a compressor comprising: a first inlet connected via a first portion of a heat exchange medium circuit to the first outlet for receiving the gaseous heat exchange medium having the first temperature and the first pressure; a second outlet for outputting the gaseous heat exchange medium having a second temperature higher than the first temperature and a second pressure higher than the first pressure after being compressed by the compressor; and an expander comprising: a second inlet, through... The second part of the heat exchange medium circuit is connected to the second outlet to receive a gaseous heat exchange medium having a second temperature and a second pressure; the generator connection port is connected to the generator (11321) to mechanically drive the generator when the gaseous heat exchange medium having a second temperature and a second pressure is expanded, so that the generator generates a second power; and the third outlet outputs a gaseous heat exchange medium having a third temperature and a third pressure lower than the second temperature after being expanded by the expander; the condenser is connected to the third outlet through the third part of the heat exchange medium circuit to receive and liquefy the gaseous heat exchange medium having a third temperature and a third pressure into a heat exchange medium; the medium pump is connected to the condenser through the fourth part of the heat exchange medium circuit to receive the heat exchange medium and is connected to the heat exchanger through the fifth part of the heat exchange medium circuit to pump the heat exchange medium to the heat exchanger.

[0007] In this way, the heat utilization system of this application combines a compressor with the heat exchanger and expander of an organic Rankine cycle system through improved design and operation. The compressor further compresses the gaseous heat exchange medium provided by the heat exchanger to produce a gaseous heat exchange medium with further increased temperature and pressure. The expander receives the gaseous heat exchange medium with further increased temperature and pressure, and mechanically drives the generator to generate electricity while expanding the gaseous heat exchange medium, thereby significantly improving the overall power generation efficiency and heat utilization rate of the fuel cell.

[0008] According to an exemplary embodiment of this application, the coolant circuit includes a first coolant pipe and a second coolant pipe connected between the fuel cell and the heat exchanger. The first coolant pipe delivers the coolant after absorbing heat to the heat exchanger, and the second coolant pipe delivers the coolant after heat exchange with the heat exchange medium back to the fuel cell.

[0009] In this way, the feature describes the specific path and function of the coolant circulation in the heat recovery device. By transferring the heat generated by the fuel cell to the heat exchanger via a first coolant pipe, this heat can be reused. Transferring heat to the heat exchanger and returning it to the fuel cell via a second coolant pipe avoids the direct release of large amounts of heat energy into the environment. Fuel cells generate high temperatures during operation, and if left uncontrolled, overheating can lead to performance degradation or even damage. Absorbing heat through the first coolant pipe and transporting it to the heat exchanger effectively reduces the operating temperature of the fuel cell, extends its lifespan, and ensures the safety and stability of the system operation.

[0010] According to an exemplary embodiment of this application, the temperature of the coolant after absorbing waste heat is 70°C-160°C.

[0011] According to an exemplary embodiment of this application, the fuel cell is a proton exchange membrane fuel cell.

[0012] In this way, a fuel cell is a device that directly converts chemical energy into electrical energy, among which the proton exchange membrane fuel cell is currently the most widely used type. During operation, PEMFCs only produce water and heat as byproducts, with no carbon dioxide emissions and no harmful substances such as nitrogen oxides and sulfides, thus being considered a very clean energy technology.

[0013] According to an exemplary embodiment of this application, it also includes a liquid storage tank connected between the condenser and the medium pump to store the liquefied heat exchange medium.

[0014] In this way, the main function of the storage tank is to optimize the system's operating efficiency and safety.

[0015] According to an exemplary embodiment of this application, the heat of the fuel cell is absorbed at the heat exchanger through the coolant circuit and converted into second electricity at the expander through the heat exchange medium circuit. The power generation efficiency of the heat utilization device is calculated as: (first electricity + second electricity) / (first electricity + heat), and the power generation efficiency is greater than or equal to 60%.

[0016] According to an exemplary embodiment of this application, the thermal utilization rate of the thermal utilization device is calculated as: second power / heat, and the thermal utilization rate is greater than or equal to 15%.

[0017] In this way, the heat recovery device can reclaim this heat and convert it into a second type of electricity, thus improving overall energy efficiency through combined heat and power (CHP). In the calculation, the first type of electricity refers to the electricity directly generated by the fuel cell, while the second type of electricity is obtained through heat conversion. Heat refers to the total amount of heat emitted by the fuel cell during operation that is not directly used to generate electricity. Comparing the sum of these two types of electricity with the sum of the first type of electricity and heat provides a clear picture of the system's utilization of waste and heat, and the improvement in overall power generation efficiency. A power generation efficiency greater than 60% means that the system can effectively utilize most of the energy, reducing waste.

[0018] According to an exemplary embodiment of this application, the heat exchange medium includes one or more of the following: propane, butane, isobutane, pentane, and pentafluoropropane.

[0019] According to an exemplary embodiment of this application, the condenser is a vacuum condenser.

[0020] According to an exemplary embodiment of this application, the compressor is a centrifugal compressor and the heat exchanger is a plate heat exchanger or a falling film evaporator.

[0021] According to an exemplary embodiment of this application, the compressor and expander are arranged coaxially.

[0022] According to an exemplary embodiment of this application, the compressor and expander are arranged non-coaxially.

[0023] According to another aspect of this application, a fuel cell heat utilization system is provided, including a fuel cell that receives hydrogen and air from the outside to carry out an electrochemical reaction to generate electricity and heat; and the aforementioned heat utilization device connected to the fuel cell to receive and utilize the heat generated by the fuel cell.

[0024] In the embodiments of this application, a technical solution is provided that efficiently combines a compressor and an organic Rankine cycle system in a simplified operation process to provide a high-temperature, high-pressure gaseous heat exchange medium to the expander in the organic Rankine cycle system, thereby improving the thermal utilization rate and overall power generation efficiency of the fuel cell. This solution at least solves the technical problems of low thermal utilization rate, low overall power generation efficiency, and complex operation process of fuel cells in the prior art, and achieves the technical effects of significantly improving the overall power generation efficiency and thermal utilization rate of fuel cells, simplifying the process, and reducing costs. Attached Figure Description

[0025] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present application and, together with the description thereof, serve to explain the present application and do not constitute an undue limitation thereof. In the drawings:

[0026] Figure 1This is a schematic diagram illustrating a heat utilization apparatus according to an exemplary embodiment of this application.

[0027] Figure 2 This is a schematic diagram illustrating a fuel cell thermal utilization system according to an exemplary embodiment of this application.

[0028] Attached icon number

[0029] 1: Fuel cell thermal utilization system;

[0030] 10: Fuel cells;

[0031] 11: Heat utilization device;

[0032] 111: Heat exchanger;

[0033] 1111: Hot entrance;

[0034] 1112: Heat exchange medium;

[0035] 1113: First Exit;

[0036] 112: Compressor;

[0037] 1121: First entrance;

[0038] 1122: Second entrance;

[0039] 113: Expander;

[0040] 1131: Second entrance;

[0041] 1132: Generator connection port;

[0042] 11321: Generator;

[0043] 1133: Third Exit;

[0044] 114: Condenser;

[0045] 115: Medium pump;

[0046] 116: First coolant pipe;

[0047] 117: Second coolant pipe;

[0048] 118: Liquid storage tank. Detailed Implementation

[0049] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings to facilitate implementation by those skilled in the art. However, the present application may be implemented in many different forms and should not be construed as limited to the embodiments described herein. In the drawings, portions unrelated to the description of the present application will be omitted for clarity. Similar reference numerals refer to similar elements throughout the description. Furthermore, while elements are represented by the same numerals in the description provided with reference to the accompanying drawings, the reference numerals relating to the elements may be varied, and the reference numerals are described only for convenience of description and should not be construed as limiting the concept, features, function, or effect of the elements to the reference numerals.

[0050] In existing technologies, fuel cells generate a significant amount of heat during operation, and the efficiency and method of utilizing this heat are key factors affecting the overall energy efficiency of the fuel cell. However, existing technologies for heat utilization in fuel cells have some shortcomings, mainly including the following:

[0051] (1) Current thermoelectric conversion materials and systems, although capable of converting some heat into electrical energy, are inefficient and costly.

[0052] (2) The heat generated by fuel cells requires precise thermal management for effective utilization. This includes multiple stages such as heat collection, storage, distribution, and conversion, each requiring advanced technology and precise control to ensure that the heat is utilized in the most efficient way without negatively impacting the operation of the fuel cell. Existing thermal management systems are often complex and costly;

[0053] (3) The heat generated by fuel cells usually needs to be converted into a specific form of energy before it can be utilized, such as hot water, steam or electricity. However, this conversion process may be affected by fluctuations in energy demand, which limits the efficiency and flexibility of heat utilization.

[0054] Solving these problems requires further research and development and technological innovation, including improving the efficiency and reliability of heat utilization equipment, simplifying thermal management systems, and reducing costs.

[0055] In view of this, this application proposes an improved thermal utilization device and a fuel cell thermal utilization system, which simplifies the thermal management system, reduces costs, and improves the thermal utilization rate and overall power generation efficiency of the fuel cell.

[0056] Figure 1 This is a schematic diagram illustrating a heat utilization apparatus according to an exemplary embodiment of the present disclosure.

[0057] Figure 2 This is a schematic diagram illustrating a fuel cell thermal utilization system according to an exemplary embodiment of the present disclosure.

[0058] like Figure 1 and Figure 2 As shown, the fuel cell heat utilization system 1 includes a fuel cell 10 and a heat utilization device 11 connected to the fuel cell 10 via a coolant circuit to receive the heat generated by the fuel cell. The heat utilization device 11 is an improvement on the organic Rankine cycle system, that is, it combines the traditional organic Rankine cycle system with a compressor.

[0059] Fuel cells come in many varieties and can be mainly classified according to electrolyte type, fuel type, and operating temperature. Common types of fuel cells include: alkaline fuel cells (AFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), solid oxide fuel cells (SOFC), and proton exchange membrane fuel cells (PEMFC).

[0060] This disclosure uses a proton exchange membrane fuel cell (PEMFC) as an example for illustration, but the fuel cell described in this disclosure is not limited to this.

[0061] Proton exchange membrane fuel cells (PEMFCs), also known as solid polymer electrolyte fuel cells, are fuel cells that generate electricity and heat through the interaction of hydrogen fuel with air. They operate at temperatures between 50°C and 100°C, requiring no pressurization or depressurization. Using a polymer proton exchange membrane as the conduction medium, they contain no chemical liquids and produce only pure water and waste heat after power generation. Among fuel cells, PEMFCs, with their relatively low temperature and atmospheric pressure characteristics, coupled with their lack of chemical hazards to humans and environmental friendliness, are suitable for everyday applications and have been developed for use in transportation power, stationary, and portable units.

[0062] The energy conversion efficiency of proton exchange membrane fuel cells is 40%–60%, and about half of the energy input from hydrogen is discharged as waste heat, resulting in energy waste. Furthermore, low-temperature proton exchange membrane fuel cells operate at relatively low temperatures, approximately 70–90°C, and their waste heat coolant temperature is also relatively low (generally not exceeding 80°C), limiting their utilization.

[0063] In this disclosure, the fuel cell 10 receives hydrogen and air from the outside through its own hydrogen inlet and air inlet, respectively, to carry out an electrochemical reaction to generate first electricity and heat. For example, in this disclosure, the fuel cell 10 can generate 500 kW of first electricity.

[0064] The heat utilization device 11 includes a heat exchanger 111, a compressor 112, an expander 113, a condenser 114, and a medium pump 115 connected in sequence through a heat exchange medium circuit.

[0065] Heat exchanger 111 is either a plate heat exchanger or a falling film evaporator. Plate heat exchangers are primarily used for heat transfer between two fluids. They consist of a series of thin metal plates that form narrow channels through which the two fluids flow, achieving efficient heat exchange. Falling film evaporators are a specific type of film evaporator, mainly used for liquid materials requiring concentration or dehydration. Their working principle involves evenly distributing the material on the inner wall of the evaporator, forming a thin film. Under heating, the water evaporates rapidly, increasing the material's concentration. Because the material forms a thin film, the contact area with the heat source is increased, resulting in fast evaporation, high efficiency, and effective utilization of thermal energy, reducing energy consumption.

[0066] The heat exchanger 111 includes a heat inlet 1111, a heat exchange medium 1112, and a first outlet 1113. The heat inlet 1111 is connected to the fuel cell 10 via a coolant circuit to receive the coolant after heat absorption. Specifically, the heat inlet 1111 is connected to the fuel cell 10 via a first coolant conduit 116 filled with coolant, which absorbs the heat generated by the fuel cell 10. The coolant that absorbs heat from the fuel cell 10 is typically water or a mixture of water-based antifreeze. In some high-performance and high-power-density applications, special coolants, such as aqueous solutions of ethylene glycol, aqueous solutions of propylene glycol, or dedicated heat transfer oils, may also be used. These coolants circulate through the cooling system of the fuel cell 10, absorbing the heat generated by the cell and then transferring it to the heat exchanger to maintain the optimal operating temperature of the fuel cell 10. For example, in this disclosure, the heat generated by the fuel cell is 448.84 kW.

[0067] In addition, a second coolant pipe 117 is connected between the fuel cell 10 and the heat exchanger 111. The second coolant pipe 117 transports the coolant after heat exchange with the heat exchange medium back to the fuel cell.

[0068] The use of the first coolant pipe 116 and the second coolant pipe 117 enables the reuse of coolant and ensures that the transfer of waste heat is not affected by external factors.

[0069] The heat exchanger 111 is filled with heat exchange medium 1112. In the organic Rankine cycle system, this heat exchange medium 1112 is also called the working fluid. The organic Rankine cycle (ORC) is a thermodynamic cycle mainly used for the recovery and utilization of low-grade heat energy, such as geothermal, industrial waste heat, and solar energy. Compared with the traditional steam Rankine cycle, the organic Rankine cycle uses organic working fluids, which have the following characteristics: (1) low boiling point: This means that the organic working fluid can boil even at a lower heat source temperature; (2) high heat of vaporization: The organic working fluid has a high heat of vaporization per unit mass, which helps to improve the cycle efficiency because more heat energy can be converted into mechanical energy under the same conditions; (3) chemical stability: The organic working fluid should have good chemical stability at high temperatures to avoid decomposition or the generation of harmful substances, while reducing the corrosiveness to system materials; (4) low viscosity and low density: These characteristics are beneficial to improving the flow performance of fluids in pipes and turbines, reducing flow resistance, and improving the overall efficiency of the system. Therefore, the heat exchange medium 112 includes at least one of the following: propane, butane, isobutane, pentane and pentafluoropropane.

[0070] The temperature of the coolant after absorbing heat from the fuel cell through the coolant circuit is 70°C-160°C. Preferably, this temperature is 70°C-85°C. Specifically, based on the operating temperature, proton exchange membranes can be divided into high-temperature proton exchange membranes (HT-PEM) and low-temperature proton exchange membranes (LT-PEM). Low-temperature proton exchange membranes typically operate in the range of 70°C-85°C; high-temperature proton exchange membranes typically operate in the range of 85°C-160°C or even higher. Both low-temperature and high-temperature proton exchange membranes have their advantages and disadvantages, and the choice depends on the specific application requirements. For example, for portable or automotive applications, low-temperature proton exchange membranes are more popular due to their lower cost and maintenance requirements; while for industrial applications requiring high efficiency and high-temperature environments, high-temperature proton exchange membranes may be a better choice.

[0071] The heat exchange medium 1112 exchanges heat with the received coolant to absorb heat from the coolant, thereby generating a first gaseous heat exchange medium having a first temperature and a first pressure. In other words, the heat exchange medium 1112 absorbs heat to reach its boiling point and boils to become the first gaseous heat exchange medium.

[0072] The first outlet 1113 outputs a first gaseous heat exchange medium with a first temperature and a first pressure.

[0073] The first inlet 1121 of the compressor 112 is connected to the first outlet 1113 via a first part of the heat exchange medium circuit to receive the first gaseous heat exchange medium; the compressor 112 compresses the first gaseous heat exchange medium, causing its temperature and pressure to increase, thus becoming a second gaseous heat exchange medium. The second outlet 1122 outputs the second gaseous heat exchange medium, which has been compressed to a second temperature higher than the first temperature and a second pressure higher than the first pressure.

[0074] The compressor 112 is, for example, a centrifugal compressor. A centrifugal compressor is a gas compression device widely used in industrial processes. It is mainly used to increase the pressure of gases to meet various industrial needs. The working principle of a centrifugal compressor is based on the conversion of kinetic energy into pressure energy. When gas is accelerated by a rotating impeller, its kinetic energy increases. Then, it decelerates in the diffuser, converting kinetic energy into pressure energy, thereby increasing the gas pressure.

[0075] In an organic Rankine cycle system, the expander 113 is also known as a turbine. The turbine (or expander) plays a crucial role in the organic Rankine cycle, serving as the core power conversion device in the entire thermodynamic cycle. Unlike the traditional steam Rankine cycle, the organic Rankine cycle uses organic working fluids (such as R134a, isopentane, etc.), which can evaporate and condense at relatively low temperatures, making them particularly suitable for utilizing low-grade heat energy, such as industrial waste heat, geothermal energy, and solar energy. The turbine or expander 113 converts the pressure energy and thermal energy of the working fluid into mechanical energy.

[0076] The second inlet 1131 of the expander 113 is connected to the second outlet via a second part of the heat exchange medium loop to receive the second gaseous heat exchange medium. The generator connection port 1132 of the expander 113 is connected to the generator 11321 to mechanically drive the generator 11321 to generate electricity during the expansion of the second gaseous heat exchange medium, thereby producing a second electrical power, for example, 69.88 kW in this disclosure. The third outlet 1133 outputs the third gaseous heat exchange medium after the second gaseous heat exchange medium has expanded to mechanically drive the generator 11321. This third gaseous heat exchange medium flows out of the expander 113, having a third temperature lower than the second temperature and a third pressure lower than the second pressure, and is also referred to as exhaust steam. During this mechanical drive, the internal energy of the second gaseous heat exchange medium is converted into mechanical energy during expansion through a significant decrease in temperature and pressure, and then indirectly into electrical energy. Therefore, by absorbing heat through the coolant circuit and then indirectly converting the absorbed heat energy into electrical energy through the heat exchange medium circuit, the thermal utilization efficiency and overall power generation efficiency of the fuel cell are effectively improved.

[0077] Compressor 112 and expander 113 can be arranged coaxially or non-coaxially. In a coaxial arrangement, compressor 112 and expander 113 share the same shaft. The advantage of this design is higher direct energy conversion efficiency because there are no additional mechanical transmission losses. In a coaxial arrangement, the compressor and expander typically rotate at the same speed and in the same direction. In a non-coaxial arrangement, the compressor and expander each have their own independent shaft. Their drive methods may differ; for example, the compressor may be driven by an electric motor, while the expander may be driven by fluid pressure. Non-coaxial arrangements offer greater design flexibility because the performance of the compressor and expander can be independently controlled and optimized, but they may also lead to a loss of energy conversion efficiency because additional transmission components (such as gearboxes) are needed to connect and coordinate their movements. The choice between coaxial and non-coaxial arrangements typically depends on the specific requirements of the application, such as space constraints, performance requirements, cost, and maintenance considerations. In some cases, a coaxial arrangement may be more preferred due to its compactness and high efficiency, while in others, a non-coaxial arrangement may be more suitable due to its design flexibility and independence.

[0078] Specifically, the working fluid is heated in the boiler or heat exchanger 111, further heated and pressurized in the compressor 112, and converted into a high-pressure gas. Upon entering the turbine or expander 113, the working fluid's pressure and temperature decrease due to the work done by its expansion as it passes through the turbine blades. The energy released in this process is converted into the rotational kinetic energy of the turbine or expander 113. Furthermore, the heating and pressurization of the compressor 112 further increases this converted kinetic energy. The expander 113 is connected to a generator 11321, which mechanically drives the generator, thereby indirectly converting heat into electricity.

[0079] Condenser 114 is connected to a third outlet via a third part of the heat exchange medium loop to receive the third gaseous heat exchange medium and liquefy it. In other words, condenser 114 liquefies the third gaseous heat exchange medium into a liquid state. This condenser is a vacuum condenser. After performing work, the second gaseous heat exchange medium typically transforms into a low-energy third gaseous heat exchange medium. Liquefying it into a liquid heat exchange medium through the condenser recovers this heat, and the liquid heat exchange medium can be reused as the heat exchange medium in heat exchanger 111, improving energy utilization efficiency. The vacuum condenser creates a vacuum environment, lowering the boiling point, making it easier for the third gaseous heat exchange medium to be liquefied. It also helps to remove non-condensable gases from the system, ensuring efficient system operation.

[0080] The medium pump 115, also known as the working fluid pump, is connected to the condenser 114 via the fourth part of the heat exchange medium loop to receive the heat exchange medium, and is connected to the heat exchanger via the fifth part of the heat exchange medium loop to pump the heat exchange medium into the heat exchanger. The main function of the medium pump is to raise the low-temperature, low-pressure liquid working fluid flowing out of the condenser 114 to a higher pressure, which is a necessary condition for the initiation of the organic Rankine cycle. By pressurizing the pump, the working fluid can reach higher temperatures and pressures in subsequent heating processes, thereby achieving sufficient evaporation in the heat exchanger 111.

[0081] In addition, the heat utilization device also includes a liquid storage tank 118 connected between the condenser and the medium pump 115 to store the liquefied heat exchange medium.

[0082] The primary function of the liquid receiver 118 is to optimize system operating efficiency and safety. Specifically, when system operating conditions change, such as a sudden increase in heat load, the liquid receiver acts as a buffer, temporarily storing excess liquid medium to prevent direct pressure surges on the medium pump or downstream equipment, thus protecting the equipment from damage. The liquid receiver 118 also helps separate gases from the liquid medium. During condensation, some gases may mix into the liquid medium; the large volume of the liquid receiver provides sufficient time for the gases to separate from the liquid, preventing air bubbles from entering the medium pump and affecting its efficiency and lifespan. Adjusting the liquid level within the liquid receiver 118 indirectly controls the flow rate of the medium pump 115, thereby maintaining a stable system operation. This is particularly important for applications requiring precise control of the heat exchange medium flow rate.

[0083] In the aforementioned embodiment, the fuel cell generates 500 kW of first-order electricity and 448.84 kW of heat. The heat from the fuel cell is absorbed at the heat exchanger via the coolant circuit and converted into 69.88 kW of second-order electricity at the expander via the heat exchange medium circuit. Therefore, the power generation efficiency of the fuel cell heat utilization system 1 is calculated as (first-order electricity + second-order electricity) / (first-order electricity + waste heat), resulting in a power generation efficiency greater than or equal to 60%. The heat utilization rate of the fuel cell heat utilization system 1 is calculated as second-order electricity / heat, resulting in a heat utilization rate greater than or equal to 15%.

[0084] Current fuel cell thermal utilization systems have an overall power generation efficiency of around 50%. The improved fuel cell thermal utilization system disclosed herein increases the overall power generation efficiency to over 60%, specifically over 65%. The improvements made in this disclosure are significant.

[0085] In the embodiments of this application, a technical solution is provided that efficiently combines a compressor and an organic Rankine cycle system in a simplified operation process to provide a high-temperature, high-pressure gaseous heat exchange medium to the expander in the organic Rankine cycle system, thereby improving the thermal utilization rate and overall power generation efficiency of the fuel cell. This solution at least solves the technical problems of low thermal utilization rate, low overall power generation efficiency, and complex operation process of fuel cells in the prior art, and achieves the technical effects of significantly improving the overall power generation efficiency and thermal utilization rate of fuel cells, simplifying the process, and reducing costs.

[0086] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0087] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways.

[0088] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A heat utilization device (11), characterized in that, The heat utilization device includes: A heat exchanger (111) includes: a heat inlet (1111) connected via a coolant circuit to an external fuel cell that generates first electricity and heat through an electrochemical reaction to receive coolant after absorbing heat from the fuel cell; a heat exchange medium (1112) that exchanges heat with the coolant to absorb heat from the coolant to generate a gaseous heat exchange medium having a first temperature and a first pressure; and a first outlet (1113) that outputs the gaseous heat exchange medium having the first temperature and the first pressure. The compressor (112) includes: a first inlet (1121) connected to the first outlet via a first portion of a heat exchange medium circuit to receive the gaseous heat exchange medium having a first temperature and a first pressure; and a second outlet (1122) outputting the gaseous heat exchange medium having a second temperature higher than the first temperature and a second pressure higher than the first pressure after being compressed by the compressor. An expander (113) includes: a second inlet (1131) connected to a second outlet via a second portion of the heat exchange medium circuit to receive a gaseous heat exchange medium having a second temperature and a second pressure; a generator connection port (1132) connected to a generator (11321) to mechanically drive the generator when the gaseous heat exchange medium having the second temperature and the second pressure is expanded, so that the generator generates a second electrical power; and a third outlet (1133) outputting a gaseous heat exchange medium having a third temperature lower than the second temperature and a third pressure lower than the second pressure after being expanded by the expander. The condenser (114) is connected to the third outlet via the third part of the heat exchange medium circuit to receive and liquefy the gaseous heat exchange medium having a third temperature and a third pressure into the heat exchange medium. A medium pump (115) is connected to the condenser through a fourth part of the heat exchange medium circuit to receive the heat exchange medium, and is connected to the heat exchanger through a fifth part of the heat exchange medium circuit to pump the heat exchange medium to the heat exchanger.

2. The heat utilization device according to claim 1, characterized in that, The coolant circuit includes a first coolant pipe (116) and a second coolant pipe (117) connected between the fuel cell and the heat exchanger. The first coolant pipe delivers the coolant after absorbing the heat to the heat exchanger, and the second coolant pipe delivers the coolant after exchanging heat with the heat exchange medium back to the fuel cell.

3. The heat utilization device according to claim 1, characterized in that, The fuel cell is a proton exchange membrane fuel cell.

4. The heat utilization device according to claim 1, characterized in that, It also includes a storage tank (118) connected between the condenser and the medium pump to store the liquefied heat exchange medium.

5. The heat utilization device according to claim 1, characterized in that, The heat from the fuel cell is absorbed at the heat exchanger through the coolant circuit and converted into the second electricity at the expander through the heat exchange medium circuit. The power generation efficiency of the heat utilization device is calculated as: (first electricity + second electricity) / (first electricity + heat), and the power generation efficiency is greater than or equal to 60%.

6. The heat utilization device according to claim 5, characterized in that, The heat utilization rate of the heat utilization device is calculated as: the second power / the heat, and the heat utilization rate is greater than or equal to 15%.

7. The heat utilization device according to claim 1, characterized in that, The condenser is a vacuum condenser.

8. The heat utilization device according to claim 1, characterized in that, The heat exchanger is a plate heat exchanger or a falling film evaporator.

9. The heat utilization device according to claim 1, characterized in that, The compressor and the expander are arranged coaxially.

10. The heat utilization device according to claim 1, characterized in that, The compressor and the expander are not arranged coaxially.

11. A fuel cell thermal utilization system (1), characterized in that, include: The fuel cell (10) receives hydrogen and air from the outside to carry out an electrochemical reaction to generate electricity and heat; as well as The heat utilization device (11) according to any one of claims 1 to 10 is connected to the fuel cell to receive and utilize the heat generated by the fuel cell.

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