A fuel cell system based on a phase change cooling architecture and a performance calculation method thereof

Abstract

The application discloses a fuel cell system based on a phase change cooling architecture and a performance calculation method thereof. The application comprises a proton exchange membrane fuel cell stack, a humidifier, a water heat exchanger, a heater, a hydrogen circulation pump and an air compressor, wherein the humidifier comprises an anode humidifier and a cathode humidifier, the water heat exchanger comprises an anode water heat exchanger and a cathode water heat exchanger, and the heater comprises an anode heater and a cathode heater; the proton exchange membrane fuel cell stack outputs a twenty-first node fluid to a expander, the expander outputs a twenty-second node fluid to a condenser, the condenser outputs a twenty-third node fluid to a working medium pump, and the working medium pump outputs a twenty-fourth node fluid to the proton exchange membrane fuel cell stack. Through the application, the problem of inaccurate calculation of performance parameters of a fuel cell system in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more particularly to a fuel cell system based on a phase change cooling architecture and a method for calculating its performance. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) possess advantages such as high efficiency, cleanliness, and rapid response, and have broad application prospects in fields such as automotive power. Traditional fuel cell thermal management mainly relies on sensible heat cooling, that is, using deionized water or water-ethylene glycol mixtures as coolants, removing heat through the temperature rise of the coolant. However, as fuel cell systems develop towards higher power densities, the bottlenecks of traditional liquid cooling solutions are becoming increasingly apparent: to remove the massive amounts of heat, extremely large coolant flow rates are required, leading to a significant increase in the parasitic power of the circulating water pump; at the same time, sensible heat cooling inevitably creates a large temperature gradient at the inlet and outlet of the stack, affecting the uniformity of the internal temperature distribution and the lifespan of the stack.

[0003] Phase change cooling technology has emerged as an emerging thermal management solution for fuel cells. PEMFC phase change cooling systems based on the Organic Rankine Cycle (ORC) utilize a low-boiling-point organic working fluid to absorb waste heat from the fuel cell in an evaporator, undergoing a phase change (vaporization). The resulting high-temperature, high-pressure steam then drives an expander to generate electricity. Finally, the steam is cooled by a condenser and pressurized by a working fluid pump before entering the next cycle. This PEMFC-ORC coupled system not only utilizes the latent heat of vaporization of the organic working fluid to achieve efficient, isothermal cooling of the fuel cell stack, improving the internal temperature distribution, but also converts waste heat into additional electrical energy, significantly improving the system's net output power and overall thermal efficiency. However, traditional performance calculation methods are based solely on energy analysis (such as energy efficiency), focusing only on the "quantity" of energy distribution and failing to reflect the essential causes of energy "quality" loss, leading to a blurred direction for system optimization. The introduction of phase change cooling systems alters the energy flow and thermodynamic coupling boundaries of the entire fuel cell system, posing entirely new challenges to the accurate calculation and evaluation of system performance.

[0004] Patent application number 202510690416.9, entitled "An Evaluation Method for Fuel Cell Air Systems Based on ΔT," discloses a technical solution: by calculating the ΔT values ​​at the inlet and outlet of the air filter, air compressor, intercooler, and humidifier respectively, the ΔT loss and ΔT efficiency of each component of the air system are obtained, and finally the ΔT loss and efficiency of the entire air system are calculated. This method only isolates the "cathode air supply subsystem" of the fuel cell for analysis, completely ignoring the electrochemical reaction heat generation inside the stack, the anode hydrogen circulation, and the crucial thermal management (cooling) system. Furthermore, it does not address how to handle the large amount of low-grade waste heat generated by the fuel cell.

[0005] Patent application number 202411172126.7, entitled "Optimization Design Method for Centrifugal Air Compressor of Fuel Cell Based on Advanced Cost Analysis," discloses a technical solution: This patent combines experimental testing with CFD numerical simulation to perform "advanced cost analysis" on the centrifugal air compressor of a fuel cell. It subdivides the cost losses inside the air compressor into internal / external and avoidable / unavoidable losses, using this as a target to guide the iterative optimization of the three-dimensional geometric parameters of the air compressor impeller and other components. This is a fluid dynamics and thermodynamics structural optimization method solely for the single mechanical component of the "centrifugal air compressor," and lacks the ability to evaluate system-level combined cycles.

[0006] Patent application number 202210996311.2, entitled "A Novel Advanced Efficiency Analysis Calculation Method for Organic Rankine Cycles," discloses a technical solution: This patent provides a general advanced efficiency analysis method for Organic Rankine Cycles (ORCs). Based on the first and second laws of thermodynamics, it calculates the energy and efficiency balance of the four conventional components of an ORC system (evaporator, expander, condenser, and working fluid pump), and decomposes efficiency losses to determine the priority of component improvements. This calculation method is designed for independent, conventional ORC systems, assuming the existence of a traditional "evaporator" for indirect heat exchange, independent of the heat source. It does not consider the special architecture of direct physical coupling between the heat source (such as a fuel cell stack) and the ORC. As an independent ORC analysis, it cannot account for the dynamic parasitic power consumption of auxiliary components such as fuel cell air compressors and humidifiers. If directly applied to fuel cell waste heat recovery, it cannot accurately reflect the net output capacity of the entire combined system.

[0007] 1. The existing fuel cell system architecture includes components such as high-pressure water pumps and deionizers in its hydrothermal management architecture, and deionized water is used as the cooling medium. Long-term use can lead to ion precipitation problems in the fuel cell stack, as well as maintenance and lifespan issues. Therefore, the hydrothermal management architecture based on phase change cooling described in this invention can eliminate the high-pressure water pump and replace it with a working fluid pump, and the deionizer can also be eliminated, thus solving the problems of excessive maintenance and ion precipitation.

[0008] 2. Insufficient depth of energy and energy analysis, unable to accurately characterize the nature of loss: Traditional energy analysis only focuses on the quantity of energy and cannot identify the location and nature of irreversible loss; traditional energy analysis mostly stays at the overall system level, lacks a refined decomposition of energy loss, and is also difficult to reveal the coupling effect between components and the law of energy quality decay, thus failing to provide a precise direction for optimization.

[0009] 3. The application scenarios of loss analysis are limited. Existing loss analysis mostly focuses on fuel cell subsystems or single thermodynamic cycles. For complete fuel cell systems such as PEMFC-ORC coupled systems, there is a lack of systematic loss analysis methods and advanced loss analysis schemes adapted to coupling characteristics.

[0010] There is currently no effective solution to the aforementioned problems in the relevant technologies. Summary of the Invention

[0011] The main objective of this application is to provide a fuel cell system based on a phase change cooling architecture and a method for calculating its performance, so as to at least solve the problem of inaccurate calculation of fuel cell system performance parameters in related technologies.

[0012] To achieve the above objectives, according to one aspect of this application, a fuel cell system based on a phase change cooling architecture is provided. The system includes: a proton exchange membrane fuel cell stack, a humidifier, a hydrothermal exchanger, a heater, a hydrogen circulation pump, and an air compressor. The humidifier includes an anode humidifier and a cathode humidifier; the hydrothermal exchanger includes an anode hydrothermal exchanger and a cathode hydrothermal exchanger; and the heater includes an anode heater and a cathode heater. The proton exchange membrane fuel cell stack outputs a 21st node fluid to an expander; the expander outputs a 22nd node fluid to a condenser; the condenser outputs a 23rd node fluid to a working fluid pump; and the working fluid pump outputs a 24th node fluid to the proton exchange membrane fuel cell stack. The first node fluid and the seventh node fluid merge to form a second node fluid that flows into the anode hydrothermal exchanger; the anode hydrothermal exchanger outputs a third node fluid that flows into the anode heater; the anode heater outputs a fourth node fluid to the anode humidifier; the anode humidifier outputs a fifth node fluid to the proton exchange membrane fuel cell stack; the proton exchange membrane fuel cell stack outputs a sixth node fluid to the hydrogen circulation pump; and the hydrogen circulation pump outputs a seventh node fluid.

[0013] Optionally, an engine is connected to the expander.

[0014] Optionally, the fluid at the eighth node flows into the air compressor, the air compressor outputs the fluid at the ninth node to the cathode water heat exchanger, the fluid at the tenth node flows out of the cathode water heat exchanger to the cathode heater, the fluid at the eleventh node flows out of the cathode heater to the cathode humidifier, and the fluid at the twelfth node flows out of the cathode humidifier to the proton exchange membrane fuel cell stack.

[0015] Optionally, the proton exchange membrane fuel cell stack discharges a thirteenth node fluid, which is divided into a sixteenth node fluid and a fourteenth node fluid; the sixteenth node fluid flows into the anode water heat exchanger, and the anode water heat exchanger outputs a seventeenth node fluid; the fourteenth node fluid flows into the cathode water heat exchanger, and the cathode water heat exchanger outputs a fifteenth node fluid.

[0016] Optionally, the fluid at the eighteenth node is divided into the fluid at the nineteenth node and the fluid at the twentieth node. The fluid at the nineteenth node flows into the anode humidifier, and the fluid at the twentieth node flows into the cathode humidifier.

[0017] On the other hand, the present invention also provides a method for calculating the performance of a fuel cell system based on a phase change cooling architecture. The method includes: performing energy analysis to obtain energy analysis results, which include the output power and heat generation of the fuel cell stack, as well as the power of each auxiliary component (hydrogen circulation pump, air compressor, water heat exchanger, heater, humidifier, expander, condenser, and working fluid pump) and the mass flow rate, temperature, and pressure of the fluid at each node; calculating the flow rate of the fluid at each node of the fuel cell system based on the energy analysis results, and calculating the flow rate loss of each component in the fuel cell system based on the flow rate balance equation of each component; decomposing the flow rate loss of each component to obtain the intrinsic flow rate loss, extrinsic flow rate loss, avoidable flow rate loss, unavoidable flow rate loss, internal avoidable flow rate loss, internal unavoidable flow rate loss, external avoidable flow rate loss, and external unavoidable flow rate loss of each component; calculating the net output power, total flow rate loss value, energy efficiency, and flow rate efficiency of the fuel cell system based on the energy analysis results and the flow rate loss of each component, and calculating the system ecological objective function to conduct a comprehensive performance evaluation of the fuel cell system.

[0018] Optionally, the output power of the fuel cell stack is calculated using the following formula: ,in, Where N is the output power of the fuel cell stack, and N is the number of individual cells. Where I is the average output voltage and I is the current density. The active area of ​​the battery; calculate the heat generation of the stack using the following formula: ,in, To generate heat for the fuel cell stack, Given a thermally neutral voltage; calculate the required hydrogen flow rate for the fuel cell stack using the following formula: ,in, Hydrogen flow rate, For the traffic of the fifth node, For the stoichiometry of the anode, Let F be the molar mass of hydrogen, and F be the Faraday constant; calculate the required air flow rate for the fuel cell stack using the following formula: ,in, For airflow, For the traffic of the twelfth node, Oxygen flow rate, This represents the mass fraction of oxygen in the air. Let O be the molar mass of oxygen; calculate the power consumption of the hydrogen circulation pump using the following formula: ,in, The power consumed by the hydrogen circulation pump For the traffic of the sixth node, The isobaric specific heat capacity of the sixth node. The fluid temperature at the sixth node. This refers to the isentropic efficiency of the hydrogen circulation pump. The fluid pressure at the seventh node. The fluid pressure at the sixth node. The specific heat ratio of the gas; calculate the outlet gas temperature of the circulating pump using the following formula: ,in, The outlet gas temperature of the circulating pump; calculate the temperature of the mixing process between fresh and recycled hydrogen using the following formula: ,in, The temperature at which new hydrogen and recycled hydrogen are mixed. For the first node's traffic, The isobaric specific heat capacity of the first node. The fluid temperature at the first node. For the traffic of the seventh node, The isobaric specific heat capacity of the seventh node. The fluid temperature at the seventh node. For the traffic of the second node, The isobaric specific heat capacity of the second node is used; the energy balance of the water-heat exchanger is calculated using the following formula: ,in, For the traffic of the sixteenth node, The isobaric specific heat capacity at the sixteenth node. The fluid temperature at the sixteenth node. For the traffic of the third node, The isobaric specific heat capacity of the third node. The fluid temperature at the third node. This refers to the traffic of the seventeenth node. The isobaric specific heat capacity of the seventeenth node. The fluid temperature at the seventeenth node; calculate the power consumed by the anode heater using the following formula: ,in, Power consumed by the anode heater For the traffic of the third node, The isobaric specific heat capacity of the third node. The fourth node fluid temperature; the energy balance of the anode humidifier, the formula is... ,in, For the traffic of the fourth node, The isobaric specific heat capacity of the fourth node, The fluid temperature at the fourth node. For the traffic of the nineteenth node, The isobaric specific heat capacity of the nineteenth node, The fluid temperature at the nineteenth node. For the traffic of the fifth node, The isobaric specific heat capacity of the fifth node. The fluid temperature at the fifth node; calculate the power consumption of the air compressor using the following formula: ,in, The power consumed by the air compressor For the traffic of the eighth node, The isobaric specific heat capacity of the eighth node. The fluid temperature at the eighth node. The isentropic efficiency of the air compressor. The fluid pressure at the eighth node. The fluid pressure at the ninth node is given; the outlet gas temperature of the air compressor is calculated, where, , The air compressor outlet gas temperature; the water-heat exchanger energy balance formula is... , For the traffic of the ninth node, The isobaric specific heat capacity of the ninth node, For the traffic of the fourteenth node, The isobaric specific heat capacity of the fourteenth node. The fluid temperature at the fourteenth node. For the traffic of the fifteenth node, The isobaric specific heat capacity at the fifteenth node. The fluid temperature at the fifteenth node. For the traffic of the tenth node, The isobaric specific heat capacity of the tenth node. The fluid temperature at the tenth node; calculate the power consumed by the cathode heater using the following formula: ,in, Power consumed by the cathode heater The fluid temperature at the eleventh node; calculate the energy balance of the cathode humidifier using the following formula: ,in, For the traffic of the eleventh node, The isobaric specific heat capacity of the eleventh node. This refers to the traffic of the twentieth node. The isobaric specific heat capacity at the twentieth node. The fluid temperature at the twentieth node. For the traffic of the twelfth node, The isobaric specific heat capacity of the twelfth node. The temperature of the fluid at the twelfth node is given; the circulating mass flow rate of the organic working fluid is calculated using the following formula: ,in, This refers to the circulating mass flow rate of the organic working fluid. To generate heat for the fuel cell stack, The specific enthalpy of the twenty-first node. The specific enthalpy of the 24th node is given; the output power of the expander is calculated using the following formula: ,in, For the expander output power, The specific enthalpy of the twenty-second node. The isentropic efficiency of the expander is given; the power consumption of the organic working fluid pump is calculated using the following formula: ,in, For the power consumption of the organic working fluid pump, This refers to the isentropic efficiency of the working fluid pump.

[0019] Optionally, calculate logistics costs using the following formula: ,in, For logistics, For fluid flow rate, For physical ratios, The chemical ratio is used to calculate the physical ratio of the fluid, and the calculation formula is as follows: ,in, For physical ratios, Let i be the specific enthalpy of node i. Let i be the specific entropy of node i. Specific enthalpy under ambient conditions. The specific entropy is given under environmental conditions; when the fluid is an ideal gas, the physical specific entropy is calculated using the following formula: ,in, For physical ratios, For isobaric specific heat capacity, For nodes temperature, For ambient temperature, For the pressure of node i, Environmental pressure; calculate the chemical ratio using the following formula: ,in, For the chemical ratio of node i, Let j be the mole fraction of component j in the mixed fluid; Let R be the standard molar chemical formula of component j, and R be the universal gas constant. Let i be the average molar mass of the fluid at node i. Let j be the molar mass of component j; calculate the loss of the hydrogen circulation pump using the following formula: ,in, For the wear and tear of the hydrogen circulation pump, For the logistics of the sixth node, The power consumed by the hydrogen circulation pump For the logistics loss of the seventh node; calculate the loss of the anode water heat exchanger using the following formula: ,in, For the loss of the anode water heat exchanger, For the logistics of the second node, For the logistics of the sixteenth node, For the logistics of the third node, For the logistics loss of the seventeenth node; calculate the loss of the anode heater using the following formula: ,in, For the loss of the anode heater, This refers to the power consumption of the anode heater. For the logistics of the third node; calculate the loss of the anode humidifier, the calculation formula is as follows: ,in, For the damage of the anode humidifier, For the logistics of the nineteenth node, For the logistics of the fifth node; calculate the loss of the air compressor, the calculation formula is as follows: ,in, For the wear and tear of the air compressor, The power consumption of the air compressor. For the logistics of the eighth node, For the logistics of the ninth node; calculate the loss of the cathode water heat exchanger, the calculation formula is as follows: ,in, For the loss of the cathode water heat exchanger, For the logistics of the fourteenth node, For the tenth node of logistics, For the logistics loss at the fifteenth node; calculate the loss of the cathode heater using the following formula: ,in, For the loss of the cathode heater, This refers to the power consumed by the cathode heater. For the logistics of the eleventh node; calculate the loss of the cathode humidifier using the following formula: ,in, For the damage of the cathode humidifier, For the twentieth node of logistics, For the logistics loss at the twelfth node; calculate the loss of the expander using the following formula: ,in, For the wear and tear of the expander, For the expander output power, For the logistics of the twenty-first node, For the logistics of the twenty-second node; calculate the loss of the condenser, the calculation formula is as follows: ,in, For condenser damage, For the logistics of the twenty-third node, For the logistics loss at node 22; calculate the loss of the working fluid pump using the following formula: ,in, For the loss of the working fluid pump, For the power consumption of the organic working fluid pump, This is the logistics for the twenty-fourth node.

[0020] Optionally, the exogenous loss is calculated using the following formula: ,in, For components Exogenous loss, For components The loss, The intrinsic loss is caused by the irreversible nature of the component itself; the avoidable loss is calculated using the following formula: ,in, For avoidable losses that have the potential to be eliminated, For components Unavoidable losses; calculate internal unavoidable losses using the following formula: ,in, For unavoidable internal losses, For components Endogenous products For components Unavoidable product losses; calculate internally avoidable losses using the following formula: ,in, Internally avoidable losses are calculated; externally unavoidable losses are calculated using the following formula: ,in, Externally unavoidable losses; externally avoidable losses are calculated using the following formula: ,in, This is to prevent external losses.

[0021] Optionally, the net output power of the combined system is calculated using the following formula: ,in, The net output power of the combined system, For the output power of the fuel cell stack, For the expander output power, The air compressor consumes power. The power consumed by the hydrogen circulation pump Power consumed by the anode heater Power consumed by the cathode heater The power consumed by the organic working fluid pump; calculate the total loss of the combined system using the following formula. ,in, The total loss value of the joint system, For components The energy loss; calculate the energy efficiency of the combined system, the calculation formula is as follows. ,in, For the energy efficiency of the combined system, The net output power of the combined system, Input the total mass flow rate of fresh hydrogen into the system. The higher heating value of hydrogen; calculate the efficiency of the combined system using the following formula: ,in, To improve the efficiency of the combined system, The standard chemical ratio of hydrogen is given; the ecological objective function of the system is calculated using the following formula: ,in, This is the objective function for systems ecology.

[0022] This application employs the following steps: performing energy analysis to obtain energy analysis results, wherein the energy analysis results include the output power and heat generation of the fuel cell stack, as well as the power of each auxiliary component (hydrogen circulation pump, air compressor, water heat exchanger, heater, humidifier, expander, condenser, and working fluid pump) and the mass flow rate, temperature, and pressure of the fluid at each node; based on the energy analysis results, calculating the flow rate of the fluid at each node of the fuel cell system, and based on the flow balance equations of each component, calculating the flow rate of each component in the fuel cell system. The system decomposes the losses based on the losses of each component, obtaining the intrinsic losses, extrinsic losses, avoidable losses, and unavoidable losses of each component, as well as internal avoidable losses, internal unavoidable losses, external avoidable losses, and external unavoidable losses. Based on the energy analysis results and the losses of each component, the net output power, total loss value, energy efficiency, and efficiency of the fuel cell system are calculated, and the system's ecological objective function is calculated to conduct a comprehensive performance evaluation of the fuel cell system. This solves the problem of inaccurate calculation of fuel cell system performance parameters in related technologies, thereby achieving the effect of accurate conventional loss analysis of coupled systems and phase change cooling links. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a fuel cell system based on a phase change cooling architecture according to an embodiment of this application;

[0025] Figure 2 This is a flowchart illustrating a method for calculating the performance of a fuel cell system based on a phase change cooling architecture, according to an embodiment of this application.

[0026] Figure 3 This is a flowchart of the performance calculation process for the PEMFC-ORC system.

[0027] Reference numerals: 31. Hydrogen circulation pump; 32. Anode water heat exchanger; 33. Anode heater; 34. Anode humidifier; 35. Air compressor; 36. Cathode water heat exchanger; 37. Cathode heater; 38. Cathode humidifier; 39. Expander; 40. Condenser; 41. Working fluid pump; 42. Generator. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] This embodiment provides a fuel cell system based on a phase change cooling architecture and a method for calculating its performance, which runs on a mobile terminal, computer terminal or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although the logical order is shown in the flowchart, in some cases the steps shown or described can be executed in a different order than that shown here.

[0033] Figure 1 This is a flowchart of a fuel cell system based on a phase change cooling architecture according to an embodiment of this application. Figure 1 As shown, the system includes:

[0034] The proton exchange membrane fuel cell stack includes a humidifier, a hydrothermal exchanger, a heater, a hydrogen circulation pump, and an air compressor. The humidifier comprises an anode humidifier and a cathode humidifier; the hydrothermal exchanger comprises an anode hydrothermal exchanger and a cathode hydrothermal exchanger; and the heater comprises an anode heater and a cathode heater. The proton exchange membrane fuel cell stack outputs fluid from node 21 to an expander; the expander outputs fluid from node 22 to a condenser; the condenser outputs fluid from node 23 to a working fluid pump; and the working fluid pump outputs fluid from node 24 to the proton exchange membrane fuel cell stack. The fluid from node 1 and node 7 merge to form fluid from node 2, which flows into the anode hydrothermal exchanger. The anode hydrothermal exchanger outputs fluid from node 3, which flows into the anode heater; the anode heater outputs fluid from node 4 to the anode humidifier; the anode humidifier outputs fluid from node 5 to the proton exchange membrane fuel cell stack; the proton exchange membrane fuel cell stack outputs fluid from node 6 to the hydrogen circulation pump; and the hydrogen circulation pump outputs fluid from node 7.

[0035] Specifically, Figure 1 The arrows indicate the fluid and its flow direction within the system, and circular numbers are used to label the fluid in different parts of the system. ORC stands for Organic Rankine Cycle Power Generation System, and PEMFC stands for Proton Exchange Membrane Fuel Cell.

[0036] This invention designs a fuel cell system based on a phase change cooling architecture. Organic refrigerant (ORC) replaces traditional cooling water, directly cooling the PEMFC stack and absorbing heat directly within the PEMFC stack to undergo a boiling phase change process. This design features a simpler system structure, achieves more efficient heat exchange between the PEMFC and ORC systems, and can further recover waste heat from the PEMFC cathode exhaust gas via a water-heat exchanger.

[0037] This PEMFC system uses hydrogen as the anode fuel and air as the cathode oxidant. Its main components include a humidifier, a water-heat exchanger, a heater, a hydrogen circulation pump, and an air compressor. The hydrogen circulation pump recovers excess hydrogen from the anode outlet and mixes it with fresh hydrogen at the inlet, improving fuel utilization efficiency and providing heating and humidification to the hydrogen entering the stack. To ensure suitable operating conditions for the PEMFC stack, the hydrogen and air entering the stack typically need to be preheated and humidified. This system uses external spray humidification, where a humidifier is installed outside the PEMFC stack to inject liquid water mist into the gas. The heater uses electric heating to heat the gas entering the humidifier.

[0038] In the ORC system, the organic working fluid fully absorbs heat from the fuel cell stack cooling channels, gradually evaporating from a liquid state through boiling, and finally flowing out of the stack as superheated steam. The superheated organic working fluid steam enters the expander to perform work, driving the generator to produce electricity. In the condenser, the organic working fluid gradually liquefies from a superheated steam state, eventually reaching a saturated liquid state. The working fluid pump pressurizes the liquid working fluid to the required evaporation pressure and flows it into the fuel cell stack. Because the organic working fluid mainly undergoes a boiling phase change process in the cooling channels, its temperature remains relatively stable during flow. Therefore, this scheme not only directly and effectively absorbs heat from the fuel cell stack but also helps maintain the uniformity of the stack temperature.

[0039] In one alternative embodiment, an engine is connected to the expander.

[0040] In an alternative embodiment, the fluid at the eighth node flows into the air compressor, the air compressor outputs the fluid at the ninth node to the cathode water heat exchanger, the fluid at the tenth node flows out of the cathode water heat exchanger to the cathode heater, the fluid at the eleventh node flows out of the cathode heater to the cathode humidifier, and the fluid at the twelfth node flows out of the cathode humidifier to the proton exchange membrane fuel cell stack.

[0041] In one alternative embodiment, the proton exchange membrane fuel cell stack discharges a thirteenth node fluid, which is divided into a sixteenth node fluid and a fourteenth node fluid; the sixteenth node fluid flows into the anode water heat exchanger, which outputs a seventeenth node fluid; the fourteenth node fluid flows into the cathode water heat exchanger, which outputs a fifteenth node fluid.

[0042] In one alternative embodiment, the eighteenth node fluid is divided into a nineteenth node fluid and a twentieth node fluid, with the nineteenth node fluid flowing into the anode humidifier and the twentieth node fluid flowing into the cathode humidifier.

[0043] Figure 2 This is a flowchart illustrating a calculation method for a fuel cell system based on a phase change cooling architecture, according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0044] Step S102: Perform energy analysis and obtain energy analysis results. The energy analysis results include the output power and heat generation of the fuel cell stack, as well as the power of each auxiliary component such as the hydrogen circulation pump, air compressor, water heat exchanger, heater, humidifier, expander, condenser and working fluid pump, and the mass flow rate, temperature and pressure of the fluid at each node.

[0045] Specifically, a full-loop energy balance model is constructed to calculate thermodynamic state parameters and component power. This includes: based on the given parameters of the fuel cell stack, hydrogen system, air system, and organic Rankine cycle cooling system, establishing energy balance equations and power calculation models for each component based on the first law of thermodynamics, and obtaining the state parameters of the fluid at each node and the parasitic power consumption or output power of each auxiliary component.

[0046] Step S102: Based on the energy analysis results, calculate the fluid flow rate of each node in the fuel cell system, and calculate the flow rate loss of each component in the fuel cell system based on the flow rate balance equation of each component.

[0047] Specifically, component equilibrium equations are established to quantify the system's conventional irreversible energy dissipation. This includes: by definition, energy exists in both energy and matter, and therefore can be categorized into energy flow energy and material flow energy based on their form. In the PEMFC system studied here, energy mainly exists in the form of work and heat; therefore, energy flow energy can be further divided into heat energy and work energy. Based on the imbalance between the chemical composition, physical state, and environment of matter, material flow energy can be divided into physical energy and chemical energy. Based on the results of energy analysis, the material flow energy (air, hydrogen, water, and organic working fluid) of each node in the combined system is calculated. .

[0048] Step S103: Based on the loss of each component, decompose the loss to obtain the intrinsic loss, extrinsic loss, avoidable loss, unavoidable loss of each component, as well as the internal avoidable loss, internal unavoidable loss, external avoidable loss, and external unavoidable loss.

[0049] Specifically, advanced performance evaluation dimensions are introduced to achieve multi-dimensional and refined decomposition of system performance loss. This includes: based on the conventional performance analysis results of step S102, which are taken as the performance loss when all components of the system are working under actual conditions, the theoretical operating conditions and unavoidable conditions of the joint system are set separately, and the conventional performance loss of each component in the system is further decomposed into endogenous, exogenous, avoidable, unavoidable, and combined performance loss components.

[0050] Assuming the k-th component operates independently under actual conditions while the remaining components operate under ideal conditions, the intrinsic efficiency loss of component k is calculated. and products ; Assuming all components operate at their highest efficiency under current technological conditions, calculate the unavoidable loss of component k. and products .

[0051] Step S104: Based on the energy analysis results and the loss of each component, calculate the net output power, total loss value, energy efficiency and efficiency of the fuel cell system, and calculate the system ecological objective function to conduct a comprehensive performance evaluation of the fuel cell system.

[0052] In one optional embodiment, the output power of the fuel cell stack is calculated using the following formula: ,in, Where N is the output power of the fuel cell stack, and N is the number of individual cells. Where I is the average output voltage and I is the current density. The active area of ​​the battery; calculate the heat generation of the stack using the following formula: ,in, To generate heat for the fuel cell stack, Given a thermally neutral voltage; calculate the required hydrogen flow rate for the fuel cell stack using the following formula: ,in, Hydrogen flow rate, For the traffic of the fifth node, For the stoichiometry of the anode, Let F be the molar mass of hydrogen, and F be the Faraday constant; calculate the required air flow rate for the fuel cell stack using the following formula: ,in, For airflow, For the traffic of the twelfth node, Oxygen flow rate, This represents the mass fraction of oxygen in the air. Let O be the molar mass of oxygen; calculate the power consumption of the hydrogen circulation pump using the following formula: ,in, The power consumed by the hydrogen circulation pump For the traffic of the sixth node, The isobaric specific heat capacity of the sixth node. The fluid temperature at the sixth node. This refers to the isentropic efficiency of the hydrogen circulation pump. The fluid pressure at the seventh node. The fluid pressure at the sixth node. The specific heat ratio of the gas; calculate the outlet gas temperature of the circulating pump using the following formula: ,in, The outlet gas temperature of the circulating pump; calculate the temperature of the mixing process between fresh and recycled hydrogen using the following formula: ,in, The temperature at which new hydrogen and recycled hydrogen are mixed. For the first node's traffic, The isobaric specific heat capacity of the first node. The fluid temperature at the first node. For the traffic of the seventh node, The isobaric specific heat capacity of the seventh node. The fluid temperature at the seventh node. For the traffic of the second node, The isobaric specific heat capacity of the second node is used; the energy balance of the water-heat exchanger is calculated using the following formula: ,in, For the traffic of the sixteenth node, The isobaric specific heat capacity at the sixteenth node. The fluid temperature at the sixteenth node. For the traffic of the third node, The isobaric specific heat capacity of the third node. The fluid temperature at the third node. This refers to the traffic of the seventeenth node. The isobaric specific heat capacity of the seventeenth node. The fluid temperature at the seventeenth node; calculate the power consumed by the anode heater using the following formula: ,in, Power consumed by the anode heater For the traffic of the third node, The isobaric specific heat capacity of the third node. The fourth node fluid temperature; the energy balance of the anode humidifier, the formula is... ,in, For the traffic of the fourth node, The isobaric specific heat capacity of the fourth node, The fluid temperature at the fourth node. For the traffic of the nineteenth node, The isobaric specific heat capacity of the nineteenth node, The fluid temperature at the nineteenth node. For the traffic of the fifth node, The isobaric specific heat capacity of the fifth node. The fluid temperature at the fifth node; calculate the power consumption of the air compressor using the following formula: ,in, The power consumed by the air compressor For the traffic of the eighth node, The isobaric specific heat capacity of the eighth node. The fluid temperature at the eighth node. The isentropic efficiency of the air compressor. The fluid pressure at the eighth node. The fluid pressure at the ninth node is given; the outlet gas temperature of the air compressor is calculated, where, , The air compressor outlet gas temperature; the water-heat exchanger energy balance formula is... , For the traffic of the ninth node, The isobaric specific heat capacity of the ninth node, For the traffic of the fourteenth node, The isobaric specific heat capacity of the fourteenth node. The fluid temperature at the fourteenth node. For the traffic of the fifteenth node, The isobaric specific heat capacity at the fifteenth node. The fluid temperature at the fifteenth node. For the traffic of the tenth node, The isobaric specific heat capacity of the tenth node. The fluid temperature at the tenth node; calculate the power consumed by the cathode heater using the following formula: ,in, Power consumed by the cathode heater The fluid temperature at the eleventh node; calculate the energy balance of the cathode humidifier using the following formula: ,in, For the traffic of the eleventh node, The isobaric specific heat capacity of the eleventh node. This refers to the traffic of the twentieth node. The isobaric specific heat capacity at the twentieth node. The fluid temperature at the twentieth node. For the traffic of the twelfth node, The isobaric specific heat capacity of the twelfth node. The temperature of the fluid at the twelfth node is given; the circulating mass flow rate of the organic working fluid is calculated using the following formula: ,in, This refers to the circulating mass flow rate of the organic working fluid. To generate heat for the fuel cell stack, The specific enthalpy of the twenty-first node. The specific enthalpy of the 24th node is given; the output power of the expander is calculated using the following formula: ,in, For the expander output power, The specific enthalpy of the twenty-second node. The isentropic efficiency of the expander is given; the power consumption of the organic working fluid pump is calculated using the following formula: ,in, For the power consumption of the organic working fluid pump, This refers to the isentropic efficiency of the working fluid pump.

[0053] In one optional embodiment, the logistics weight is calculated using the following formula: ,in, For logistics, For fluid flow rate, For physical ratios, The chemical ratio is used to calculate the physical ratio of the fluid, and the calculation formula is as follows: ,in, For physical ratios, Let i be the specific enthalpy of node i. Let i be the specific entropy of node i. Specific enthalpy under ambient conditions. The specific entropy is given under environmental conditions; when the fluid is an ideal gas, the physical specific entropy is calculated using the following formula: ,in, For physical ratios, For isobaric specific heat capacity, For nodes temperature, For ambient temperature, For the pressure of node i, Environmental pressure; calculate the chemical ratio using the following formula: ,in, For the chemical ratio of node i, Let j be the mole fraction of component j in the mixed fluid; Let R be the standard molar chemical formula of component j, and R be the universal gas constant. Let i be the average molar mass of the fluid at node i. Let j be the molar mass of component j; calculate the loss of the hydrogen circulation pump using the following formula: ,in, For the wear and tear of the hydrogen circulation pump, For the logistics of the sixth node, The power consumed by the hydrogen circulation pump For the logistics loss of the seventh node; calculate the loss of the anode water heat exchanger using the following formula: ,in, For the loss of the anode water heat exchanger, For the logistics of the second node, For the logistics of the sixteenth node, For the logistics of the third node, For the logistics loss of the seventeenth node; calculate the loss of the anode heater using the following formula: ,in, For the loss of the anode heater, This refers to the power consumption of the anode heater. For the logistics of the third node; calculate the loss of the anode humidifier, the calculation formula is as follows: ,in, For the damage of the anode humidifier, For the logistics of the nineteenth node, For the logistics of the fifth node; calculate the loss of the air compressor, the calculation formula is as follows: ,in, For the wear and tear of the air compressor, The power consumption of the air compressor. For the logistics of the eighth node, For the logistics of the ninth node; calculate the loss of the cathode water heat exchanger, the calculation formula is as follows: ,in, For the loss of the cathode water heat exchanger, For the logistics of the fourteenth node, For the tenth node of logistics, For the logistics loss at the fifteenth node; calculate the loss of the cathode heater using the following formula: ,in, For the loss of the cathode heater, This refers to the power consumed by the cathode heater. For the logistics of the eleventh node; calculate the loss of the cathode humidifier using the following formula: ,in, For the damage of the cathode humidifier, For the twentieth node of logistics, For the logistics loss at the twelfth node; calculate the loss of the expander using the following formula: ,in, For the wear and tear of the expander, For the expander output power, For the logistics of the twenty-first node, For the logistics of the twenty-second node; calculate the loss of the condenser, the calculation formula is as follows: ,in, For condenser damage, For the logistics of the twenty-third node, For the logistics loss at node 22; calculate the loss of the working fluid pump using the following formula: ,in, For the loss of the working fluid pump, For the power consumption of the organic working fluid pump, This is the logistics for the twenty-fourth node.

[0054] In one optional embodiment, the exogenous efflux loss is calculated using the following formula: ,in, For components Exogenous loss, For components The loss, The intrinsic loss is caused by the irreversible nature of the component itself; the avoidable loss is calculated using the following formula: ,in, For avoidable losses that have the potential to be eliminated, For components Unavoidable losses; calculate internal unavoidable losses using the following formula: ,in, For unavoidable internal losses, For components Endogenous products For components Unavoidable product losses; calculate internally avoidable losses using the following formula: ,in, Internally avoidable losses are calculated; externally unavoidable losses are calculated using the following formula: ,in, Externally unavoidable losses; externally avoidable losses are calculated using the following formula: ,in, This is to prevent external losses.

[0055] In an optional embodiment, the net output power of the combined system is calculated using the following formula: ,in, The net output power of the combined system, For the output power of the fuel cell stack, For the expander output power, The air compressor consumes power. The power consumed by the hydrogen circulation pump Power consumed by the anode heater Power consumed by the cathode heater The power consumed by the organic working fluid pump; calculate the total loss of the combined system using the following formula. ,in, The total loss value of the joint system, For components The energy loss; calculate the energy efficiency of the combined system, the calculation formula is as follows. ,in, For the energy efficiency of the combined system, The net output power of the combined system, Input the total mass flow rate of fresh hydrogen into the system. The higher heating value of hydrogen; calculate the efficiency of the combined system using the following formula: ,in, To improve the efficiency of the combined system, The standard chemical ratio of hydrogen is given; the ecological objective function of the system is calculated using the following formula: ,in, This is the objective function for systems ecology.

[0056] Specifically, under certain operating conditions, the net output power of a system reflects its ability to provide power to external systems and is an important performance indicator for evaluating the overall system performance. It can be expressed as: The total energy loss of the system reflects the loss of the maximum available energy in the system and is of great significance for measuring the energy conversion performance of the PEMFC system. Based on the energy balance equation mentioned above, the energy loss of each component in the system can be calculated separately. Therefore, the total energy loss of the PEMFC system is the sum of the energy losses of each component, which can be expressed as: System energy efficiency reflects the ability of a PEMFC system to fully convert and utilize the chemical energy of fuel. Higher energy efficiency means superior energy saving, which can be expressed as: System efficiency is the efficiency with which the input work of a PEMFC system is converted into net output work. It reflects the ability of a PEMFC system to fully convert energy from the perspective of the second law of thermodynamics, and its expression is: The ecological objective function is the difference between the system's net output power and total entropy loss, representing a performance index that optimizes the trade-off between output power and entropy production. Its main goal is to maximize net output power while minimizing the system's total entropy loss. These multi-dimensional evaluation indicators can accurately guide parameter optimization and energy efficiency evaluation of phase change cooling systems under different operating conditions.

[0057] Through this embodiment, the purpose of this invention is to overcome the shortcomings of existing technologies in the modeling of PEMFC-ORC phase change cooling coupled systems, such as fragmented modeling, inaccurate loss quantification, and ambiguous optimization directions. It constructs an integrated thermodynamic model of the PEMFC-ORC phase change cooling coupled system, enabling accurate conventional analysis of the coupled system and phase change cooling components. It establishes an advanced loss decomposition method for this coupled system, quantifying component self-losses and interactive losses, as well as avoidable and unavoidable losses. This provides precise theoretical support for the structural design and operational parameter adjustment of the coupled system, solving the problems of large modeling errors, incomplete loss quantification, and lack of optimization basis in existing technologies.

[0058] In an alternative embodiment, reference is made to Figure 3 :

[0059] First, the initial conditions for the simulation calculation are set (mainly including the operating parameters of the PEMFC stack and environmental state parameters). Then, based on the actual operating characteristics of different components and energy conservation, a thermodynamic first-law model of each device in the system is established. The component models are connected in series to form the three major circulation loops of the PEMFC system: the anode circulation loop, the cathode circulation loop, and the phase change cooling circulation loop, constructing a full-loop energy balance model. Based on the above thermodynamic modeling process, the output or power consumption of each component in the system, as well as the state parameters of the inlet and outlet fluids, are calculated.

[0060] Subsequently, energy balance equations for each component of the system were established. Based on the second law of thermodynamics and combined with the obtained fluid state parameters (temperature, pressure, composition, flow rate, etc.) at the inlet and outlet of each component, the energy of the material (including physical and chemical energy), work energy, and heat energy were calculated respectively. These were then substituted into the energy balance equations to complete conventional energy analysis, thereby obtaining the total energy loss of each component of the system, as well as the fluid energy data at the inlet and outlet of each component, clarifying the energy transfer and loss laws of the entire loop of the PEMFC-ORC system.

[0061] Subsequently, an advanced performance analysis model was established for the system. Considering the multi-component coupling characteristics of the three major loops (anode, cathode, and phase change cooling) in the PEMFC-ORC system, a two-level performance loss decomposition framework was constructed: internal / external and avoidable / unavoidable. Internal performance losses correspond to irreversible losses during the component's own operation (such as electrochemical reactions in the PEMFC stack, air compressor compression, and ORC working fluid phase change heat transfer). External performance losses correspond to additional losses generated during interactions between the component and other components within the system and the environment. Avoidable performance losses are those that can be eliminated through structural optimization, parameter adjustment, and working fluid selection optimization. Unavoidable performance losses are inherent losses that cannot be eliminated due to the physical properties and thermodynamic limits of the working fluid. Through iterative calculations using the advanced performance analysis model, four types of refined performance loss results for each component were obtained. This accurately distinguishes the attributes and optimization feasibility of performance losses for each component, clarifies the root causes and optimization priorities of performance losses for different components, and provides precise data support for targeted optimization of the PEMFC-ORC system.

[0062] Finally, based on the full-process energy calculation, conventional energy analysis, and advanced energy decomposition results, a comprehensive evaluation of the thermodynamic performance of the PEMFC-ORC system was conducted. This evaluation integrated multiple dimensions of indicators, including net output power, energy efficiency, energy efficiency, total energy loss, and ecological objective function, to fully quantify the system's energy utilization level, energy loss control effect, and overall operating performance. This completed the full-process calculation and evaluation of the PEMFC-ORC system's performance, providing a theoretical basis for the system's structural design, parameter optimization, and engineering applications.

[0063] The technical effects achieved by this invention are as follows:

[0064] 1. This invention uses an insulating organic working fluid to be directly introduced into the fuel cell stack channel for boiling phase change cooling, eliminating the need for a separate evaporator in traditional ORCs, simplifying the system structure while enhancing the synergistic effect of electrochemical reaction and working fluid phase change.

[0065] 2. This invention introduces an advanced performance analysis and calculation model, breaking through the limitations of traditional evaluation methods that only quantify the total performance loss of components. This method sets ideal and unavoidable cyclic boundaries, decomposing the irreversible dissipation of each component into intrinsic, extrinsic, avoidable, and unavoidable components. It can isolate external losses transferred from other components and clearly identify the physical limitations imposed by current technology, accurately pinpointing system components with true optimization potential.

[0066] 3. The system-level thermodynamic calculation model constructed in this invention fully encompasses the cathode air system, the anode hydrogen circulation loop, and the phase change cooling loop. It accurately obtains key parameters at each state point, clarifies the coupling relationship between energy flow and mass flow, and realizes global energy coupling between the stack under variable load conditions and the power consumption of the entire loop.

[0067] 4. This invention constructs a multi-dimensional performance evaluation system encompassing net system output power, overall energy efficiency, thermal efficiency, and ecological objective function. This multi-dimensional mathematical evaluation mechanism provides a comprehensive basis for parameter calibration, scientifically guiding the phase change cooling system to achieve the optimal balance between improving overall energy efficiency and reducing thermodynamic losses.

[0068] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0069] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A fuel cell system based on a phase change cooling architecture, characterized in that, include: A proton exchange membrane fuel cell stack, a humidifier, a water heat exchanger, a heater, a hydrogen circulation pump, and an air compressor, wherein the humidifier includes an anode humidifier and a cathode humidifier, the water heat exchanger includes an anode water heat exchanger and a cathode water heat exchanger, and the heater includes an anode heater and a cathode heater. The proton exchange membrane fuel cell stack outputs the twenty-first node fluid to the expander, the expander outputs the twenty-second node fluid to the condenser, the condenser outputs the twenty-third node fluid to the working fluid pump, and the working fluid pump outputs the twenty-fourth node fluid to the proton exchange membrane fuel cell stack. The first node fluid and the seventh node fluid merge to form the second node fluid, which flows into the anode water heat exchanger. The anode water heat exchanger outputs the third node fluid, which flows into the anode heater. The anode heater outputs the fourth node fluid to the anode humidifier. The anode humidifier outputs the fifth node fluid to the proton exchange membrane fuel cell stack. The proton exchange membrane fuel cell stack outputs the sixth node fluid to the hydrogen circulation pump. The hydrogen circulation pump outputs the seventh node fluid.

2. The system according to claim 1, characterized in that, include: An engine is connected to the expander.

3. The system according to claim 1, characterized in that, include: The fluid from the eighth node flows into the air compressor, the air compressor outputs the fluid from the ninth node to the cathode water heat exchanger, the fluid from the tenth node flows out of the cathode water heat exchanger to the cathode heater, the fluid from the eleventh node flows out of the cathode heater to the cathode humidifier, and the fluid from the twelfth node flows out of the cathode humidifier to the proton exchange membrane fuel cell stack.

4. The system according to claim 3, characterized in that, include: The proton exchange membrane fuel cell stack discharges a thirteenth node fluid, which is divided into a sixteenth node fluid and a fourteenth node fluid. The fluid at the sixteenth node flows into the anode water heat exchanger, and the fluid at the seventeenth node outputs from the anode water heat exchanger. The fluid at the fourteenth node flows into the cathode water heat exchanger, and the cathode water heat exchanger outputs the fluid at the fifteenth node.

5. The system according to claim 3, characterized in that, include: The fluid at the eighteenth node is divided into the fluid at the nineteenth node and the fluid at the twentieth node. The fluid at the nineteenth node flows into the anode humidifier, and the fluid at the twentieth node flows into the cathode humidifier.

6. A method for calculating the performance of a fuel cell system based on a phase change cooling architecture, applied to a fuel cell system based on a phase change cooling architecture as described in any one of claims 1-5, characterized in that, include: Energy analysis is performed to obtain energy analysis results, which include the output power and heat generation of the fuel cell stack, as well as the power of each auxiliary component such as the hydrogen circulation pump, air compressor, water heat exchanger, heater, humidifier, expander, condenser and working fluid pump, and the mass flow rate, temperature and pressure of the fluid at each node; Based on the energy analysis results, the fluid flow rate of each node in the fuel cell system is calculated, and based on the flow rate balance equations of each component, the flow rate loss of each component in the fuel cell system is calculated. Based on the loss of each component, the loss is decomposed to obtain the intrinsic loss, extrinsic loss, avoidable loss, unavoidable loss of each component, as well as the internal avoidable loss, internal unavoidable loss, external avoidable loss, and external unavoidable loss of each component. Based on the energy analysis results and the energy losses of each component, the net output power, total energy loss, energy efficiency, and energy efficiency of the fuel cell system are calculated, and the system ecological objective function is calculated to conduct a comprehensive performance evaluation of the fuel cell system.

7. The method according to claim 6, characterized in that, Perform energy analysis and obtain the energy analysis results, including: The formula for calculating the output power of the fuel cell stack is as follows: ,in, The output power of the fuel cell stack is N, where N is the number of individual cells. Where I is the average output voltage and I is the current density. The active area of ​​the battery; The formula for calculating the heat generation of the fuel cell stack is as follows: ,in, To generate heat for the fuel cell stack, It is the thermal neutral voltage; The required hydrogen flow rate for the fuel cell stack is calculated using the following formula: ,in, Hydrogen flow rate, For the traffic of the fifth node, For the stoichiometry of the anode, Let F be the molar mass of hydrogen gas, and F be the Faraday constant. The required air flow rate for the fuel cell stack is calculated using the following formula: ,in, The airflow rate is... For the traffic of the twelfth node, Oxygen flow rate, This represents the mass fraction of oxygen in the air. Here is the molar mass of oxygen. The power consumption of the hydrogen circulation pump is calculated using the following formula: ,in, The power consumed by the hydrogen circulation pump, For the traffic of the sixth node, The isobaric specific heat capacity of the sixth node. The fluid temperature at the sixth node. This refers to the isentropic efficiency of the hydrogen circulation pump. The fluid pressure at the seventh node. For the fluid pressure at the sixth node, This refers to the specific heat ratio of the gas. The formula for calculating the outlet gas temperature of the circulating pump is as follows: ,in, This refers to the outlet gas temperature of the circulating pump. The temperature during the mixing process of fresh and recycled hydrogen is calculated using the following formula: ,in, The temperature at which new hydrogen and recycled hydrogen are mixed. For the first node's traffic, The isobaric specific heat capacity of the first node. The fluid temperature at the first node. For the traffic of the seventh node, The isobaric specific heat capacity of the seventh node. The fluid temperature at the seventh node. For the traffic of the second node, The isobaric specific heat capacity of the second node; The energy balance of a water-heat exchanger is calculated using the following formula: ,in, For the traffic of the sixteenth node, The isobaric specific heat capacity at the sixteenth node. The fluid temperature at the sixteenth node. For the traffic of the third node, The isobaric specific heat capacity of the third node. The fluid temperature at the third node. This refers to the traffic of the seventeenth node. The isobaric specific heat capacity at the seventeenth node. The fluid temperature at the seventeenth node; The power consumption of the anode heater is calculated using the following formula: ,in, Power consumed by the anode heater For the traffic of the third node, The isobaric specific heat capacity of the third node. The fluid temperature at the fourth node; Energy balance of an anode humidifier, the formula is: ,in, For the traffic of the fourth node, The isobaric specific heat capacity of the fourth node, The fluid temperature at the fourth node. For the traffic of the nineteenth node, The isobaric specific heat capacity of the nineteenth node, The fluid temperature at the nineteenth node. For the traffic of the fifth node, The isobaric specific heat capacity of the fifth node. The fluid temperature at the fifth node; The formula for calculating the power consumption of an air compressor is as follows: ,in, The power consumed by the air compressor. For the traffic of the eighth node, The isobaric specific heat capacity of the eighth node, The fluid temperature at the eighth node. The isentropic efficiency of the air compressor. For the fluid pressure at the eighth node, The fluid pressure at the ninth node; Calculate the outlet gas temperature of the air compressor, where, , The outlet gas temperature of the air compressor; The energy balance formula for a water-heat exchanger is: , For the traffic of the ninth node, The isobaric specific heat capacity of the ninth node, For the traffic of the fourteenth node, The isobaric specific heat capacity of the fourteenth node. The fluid temperature at the fourteenth node. For the traffic of the fifteenth node, The isobaric specific heat capacity at the fifteenth node. The fluid temperature at the fifteenth node. For the traffic of the tenth node, The isobaric specific heat capacity of the tenth node. The fluid temperature at the tenth node; The formula for calculating the power consumption of the cathode heater is as follows: ,in, Power consumed by the cathode heater The fluid temperature at the eleventh node; The energy balance of a cathode humidifier is calculated using the following formula: ,in, For the traffic of the eleventh node, The isobaric specific heat capacity of the eleventh node. This refers to the traffic of the twentieth node. The isobaric specific heat capacity at the twentieth node. The fluid temperature at the twentieth node. For the traffic of the twelfth node, The isobaric specific heat capacity of the twelfth node. The fluid temperature at the twelfth node; The formula for calculating the circulating mass flow rate of the organic working fluid is as follows: ,in, This refers to the circulating mass flow rate of the organic working fluid. To generate heat for the fuel cell stack, The specific enthalpy of the twenty-first node. The specific enthalpy of the twenty-fourth node; The formula for calculating the expander output power is as follows: ,in, For the expander output power, The specific enthalpy of the twenty-second node. The isentropic efficiency of the expander; The power consumption of an organic working fluid pump is calculated using the following formula: ,in, The power consumed by the organic working fluid pump. This refers to the isentropic efficiency of the working fluid pump.

8. The method according to claim 6, characterized in that, Based on the energy analysis results, the fluid flow rate at each node of the fuel cell system is calculated, and based on the flow rate balance equations of each component, the flow rate loss of each component in the fuel cell system is calculated, including: The calculation formula is as follows: ,in, For the aforementioned logistics, For fluid flow rate, For physical ratios, For chemical ratio; The physical ratio of a computational fluid is calculated using the following formula: ,in, For physical ratios, Let i be the specific enthalpy of node i. Let i be the specific entropy of node i. Specific enthalpy under ambient conditions. Specific entropy under environmental conditions; When the fluid is an ideal gas, the physical ratio is calculated using the following formula: ,in, For physical ratios, For isobaric specific heat capacity, For nodes temperature, For ambient temperature, For the pressure of node i, Due to environmental pressures; The chemical ratio is calculated using the following formula: ,in, For the chemical ratio of node i, Let j be the mole fraction of component j in the mixed fluid; Let R be the standard molar chemical formula of component j, and R be the universal gas constant. Let i be the average molar mass of the fluid at node i. Let be the molar mass of component j; The calculation formula for the loss of the hydrogen circulation pump is as follows: ,in, For the wear and tear of the hydrogen circulation pump, For the logistics of the sixth node, The power consumed by the hydrogen circulation pump Logistics for the seventh node; The calculation formula for the loss of the anode water heat exchanger is as follows: ,in, For the loss of the anode water heat exchanger, For the logistics of the second node, For the logistics of the sixteenth node, For the logistics of the third node, Logistics for the seventeenth node; The formula for calculating the loss of the anode heater is as follows: ,in, The loss of the anode heater, This refers to the power consumption of the anode heater. For logistics at the third node; The calculation formula for the loss of an anode humidifier is as follows: ,in, For the loss of the anode humidifier, For the logistics of the nineteenth node, For the logistics of the fifth node; The formula for calculating the loss of an air compressor is as follows: ,in, The wear and tear of the air compressor. The power consumption of the air compressor. For the logistics of the eighth node, Logistics for the ninth node; The calculation formula for the loss of the cathode water heat exchanger is as follows: ,in, For the loss of the cathode water heat exchanger, For the logistics of the fourteenth node, For the tenth node of logistics, Logistics for the fifteenth node; The calculation formula for the loss of the cathode heater is as follows: ,in, For the loss of the cathode heater, This refers to the power consumed by the cathode heater. Logistics for the eleventh node; The formula for calculating the loss of a cathode humidifier is as follows: ,in, For the damage of the cathode humidifier, For the twentieth node of logistics, Logistics for the twelfth node; The formula for calculating the expansion loss is as follows: ,in, The loss of the expander For the expander output power, For the logistics of the twenty-first node, Logistics for the twenty-second node; The formula for calculating condenser losses is as follows: ,in, For the loss of the condenser, For the logistics of the twenty-third node, Logistics for the twenty-second node; The formula for calculating the working fluid pump loss is as follows: ,in, The loss of the working fluid pump, For the power consumption of the organic working fluid pump, This is the logistics for the twenty-fourth node.

9. The method according to claim 6, characterized in that, Based on the loss of each component, the loss is decomposed to obtain the intrinsic loss, extrinsic loss, avoidable loss, and unavoidable loss of each component, as well as the internal avoidable loss, internal unavoidable loss, external avoidable loss, and external unavoidable loss, including: The formula for calculating exogenous loss is as follows: ,in, For components Exogenous loss, For components The loss, The loss is an intrinsic damage caused by the irreversible nature of the component itself. Calculations can avoid losses; the calculation formula is as follows: ,in, For avoidable losses that have the potential to be eliminated, For components The unavoidable loss; The formula for calculating unavoidable internal losses is as follows: ,in, For unavoidable internal losses, For components Endogenous products For components An unavoidable product; The internal calculation can avoid losses, and the calculation formula is as follows: ,in, To avoid internal losses; The formula for calculating unavoidable external losses is as follows: ,in, Unavoidable external losses; The formula for calculating avoidable external losses is as follows: ,in, This is to prevent external losses.

10. The method according to claim 6, characterized in that, Based on the energy analysis results and the losses of each component, the net output power, total loss value, energy efficiency, and efficiency of the fuel cell system are calculated. The system's ecological objective function is also calculated to perform a comprehensive performance evaluation of the fuel cell system, including: The net output power of the combined system is calculated using the following formula: ,in, The net output power of the combined system, For the output power of the fuel cell stack, For the expander output power, The air compressor consumes power. The power consumed by the hydrogen circulation pump Power consumed by the anode heater Power consumed by the cathode heater Power consumed by the organic working fluid pump; The total loss of the joint system is calculated using the following formula: ,in, The total loss value of the joint system, For components The loss; The energy efficiency of the combined system is calculated using the following formula: ,in, The energy efficiency of the combined system, The net output power of the combined system, Input the total mass flow rate of fresh hydrogen into the system. This is the higher heating value of hydrogen. The formula for calculating the efficiency of a joint system is as follows: ,in, To improve the efficiency of the combined system, The standard chemical ratio of hydrogen is 1000 ppm. The ecological objective function of the computational system is calculated using the following formula: ,in, This is the objective function for systems ecology.

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