Fuel cell-based air system evaluation method

Abstract

The invention relates to a fuel cell air system evaluation method based on # imgabs0 #, and belongs to the technical field of fuel cells. A fuel cell air system comprises an air filter, an air compressor, an intercooler and a humidifier; the method is characterized by comprising the following steps that S1, the # imgabs 1 # value of the air filter inlet and outlet working medium is calculated; s2, calculating # imgabs2 # values of the working media at the inlet and the outlet of the air compressor; s3, calculating a # imgabs3 # value of the working medium at the inlet and the outlet of the intercooler; s4, calculating a # imgabs4 # value of the working medium at the inlet and the outlet of the humidifier; and S5, respectively obtaining # imgabs6 loss and # imgabs7 efficiency of the air filter, the air compressor, the intercooler and the humidifier according to the # imgabs5 values of the working media at the inlets and outlets of the air filter, the air compressor, the intercooler and the humidifier, and finally obtaining # imgabs8 loss and # imgabs9 efficiency of the fuel cell air system.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells and relates to a fuel cell-based Fuel cell air system evaluation method based on Background Art

[0002] Fuel cells, as a highly efficient and low-pollution power generation technology, have been widely used in various fields, including transportation, distributed energy, and portable devices. The fuel cell air system, a critical auxiliary subsystem for fuel cell stack operation, significantly impacts the overall efficiency, dynamic response, and lifespan of the fuel cell. The air system primarily consists of components such as an air filter, air compressor, intercooler, and humidifier. Its mission is to provide the fuel cell stack with air at the appropriate flow rate, pressure, temperature, and humidity to meet its operational requirements.

[0003] In recent years, with the rapid development of fuel cell technology, higher requirements have been placed on the performance optimization and system integration of air systems. The design and development of fuel cell air systems have gradually shifted from traditional empirical methods to a systematic approach based on coupled analysis of thermodynamics, fluid mechanics, and control engineering. In order to achieve high-efficiency operation and minimize energy consumption of air systems, academia and industry generally use forward modeling, computational fluid dynamics (CFD) simulation, test platform evaluation and other methods to analyze and optimize system performance. However, since the air system involves multiple components, multiple variables, and multiple operating conditions, its operation process exhibits obvious nonlinear characteristics. Especially under non-isothermal conditions, there are complex heat-flow-humidity multi-physics field coupling transfer phenomena in the system, making it difficult to fully grasp the system's energy conversion and loss mechanisms.

[0004] At present, the performance evaluation of fuel cell air systems mainly relies on the following methods: Energy efficiency analysis: Based on the law of conservation of energy, it analyzes the input and output energy and evaluates the efficiency of the system, but it cannot identify the loss location in the irreversible process; CFD simulation analysis: It can simulate the flow and heat transfer details within the components, but the model construction is complex and the computational cost is high, making it difficult to use for rapid system-level evaluation; Test platform testing: It obtains actual performance data of the system or components, but the experimental cost is high and the cycle is long, making it difficult to meet the needs of rapid design evaluation; Multi-objective optimization method: It uses multidisciplinary optimization algorithms to balance different performance indicators, but the ability to identify loss mechanisms and system potential is limited.

[0005] In existing research, although some scholars have introduced Exergy Analysis attempts to reveal the energy quality and irreversibility issues of the system, but it focuses more on the thermal management system of the fuel cell stack or the overall system level, and does not focus on the air system, which is a key auxiliary system. Characterization research is still incomplete and lacks systematic component-level Loss identification methods and evaluation process.

[0006] At present, the fuel cell air system is under design and development. The operation process of each component of the system is complex, involving the coordinated changes of multiple parameters such as temperature, humidity, and pressure. Traditional energy analysis cannot accurately identify the location and nature of irreversible losses. The lack of scientific quantitative methods for the distribution and loss mechanism of Exergy limits the identification of performance bottlenecks and the exploration of system optimization space; the lack of unified and systematic Evaluation methods make it difficult to effectively compare and optimize the energy efficiency levels of air systems and their key components; current air systems are mostly optimized and designed using empirical methods, which lack theoretical support and are difficult to adapt to multi-objective trade-off design and efficient integration requirements. Summary of the Invention

[0007] In view of this, the object of the present invention is to provide a Fuel cell air system evaluation method.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A kind of A fuel cell air system evaluation method comprising the following steps:

[0010] S1: Calculate the working fluid at the inlet and outlet of the air filter value;

[0011] S2: Calculate the working fluid at the inlet and outlet of the air compressor value;

[0012] S3: Calculate the working fluid at the inlet and outlet of the intercooler value;

[0013] S4: Calculate the working fluid at the inlet and outlet of the humidifier value;

[0014] S5: According to the working fluid of the air filter, air compressor, intercooler and humidifier The values ​​of air filter, air compressor, intercooler and humidifier are obtained respectively. Loss and efficiency, and ultimately the fuel cell air system Loss and efficiency.

[0015] Furthermore, step S1 specifically includes the following steps:

[0016] S11: Calculate the working fluid composition and working fluid state at the air filter inlet;

[0017] S12: Calculate the working fluid composition and working fluid state at the air filter outlet;

[0018] S13: Calculate the working fluid at the inlet and outlet of the air filter value.

[0019] Furthermore, step S11 specifically includes the following steps:

[0020] S111: Calculate the oxygen flow rate at the air filter inlet; the oxygen flow rate at the air filter inlet is obtained by theoretical calculation based on the operating conditions of the fuel cell stack, and its size is equal to the oxygen flow rate at the cathode inlet. The calculation formula is:

[0021]

[0022] in, is the oxygen flow rate at the air filter inlet, is the oxygen flow rate at the cathode inlet of the stack, is the oxygen peroxide ratio, is the molar mass of oxygen, N is the number of cells in the stack, I cell is the working current density of the stack, A cell is the active area of ​​the battery stack cell, and F is the Faraday constant;

[0023] S112: Calculate the nitrogen flow rate at the air filter inlet; the ratio of the nitrogen flow rate to the oxygen flow rate at the air filter inlet is 0.79:0.21, and the calculation formula is:

[0024]

[0025] in, is the oxygen flow rate at the air filter inlet, is the nitrogen flow rate at the cathode inlet of the stack;

[0026] S113: Calculate the water vapor flow rate at the air filter inlet; the water vapor flow rate at the air filter inlet is the saturated water vapor flow rate contained in the air, where the relative humidity of the air is 50%, and the calculation formula is:

[0027]

[0028] in, is the water vapor flow rate at the air filter inlet, N af,air The flow rate of the mixed working medium of oxygen and nitrogen at the air filter inlet is the molar mass of water, M air is the molar mass of the mixed working medium of oxygen and nitrogen at the air filter inlet, RH air is the relative humidity of the air, is the saturated steam pressure at the air filter inlet, obtained by looking up the table using Refprop software; P af,inis the air filter inlet pressure; and are the molar masses of nitrogen and oxygen, respectively;

[0029] S114: Calculating the working medium state at the air filter inlet; the temperature and pressure state of the mixed working medium at the air filter inlet are the same as the temperature and pressure state of the air.

[0030] Furthermore, the step S12 specifically includes the following steps:

[0031] S121: Calculating the working fluid composition at the air filter outlet; the mixed working fluid composition at the air filter outlet is the same as the mixed working fluid composition at the air filter inlet;

[0032] S122: Calculate the working medium state at the air filter outlet; the mixed working medium temperature of the air filter is the same as the air filter inlet temperature, and the mixed working medium pressure is the difference between the atmospheric pressure and the flow resistance of the mixed working medium of the air filter. The calculation formula is:

[0033] Air filter outlet pressure = air filter inlet pressure - air filter flow resistance.

[0034] Furthermore, the step S13 specifically includes the following steps:

[0035] S131: Calculate the enthalpy of the working fluid at the inlet and outlet of the air filter; the enthalpy of the mixed working fluid at the inlet and outlet of the air filter is obtained by looking up the table according to the composition and state of the mixed working fluid, and is expressed as:

[0036] H af =refpropm(′H′,′T′,T af ,′P′,P af ,′oxygen′,′nitrogen′,′water′,x af )

[0037] Among them, T af is the temperature corresponding to the air filter inlet or outlet, P af is the pressure corresponding to the air filter inlet or outlet, x af The mixed working fluid components corresponding to the air filter inlet or outlet;

[0038] S132: Calculate the entropy value of the working fluid at the inlet and outlet of the air filter; the mixed working fluid at the inlet and outlet of the air filter includes oxygen, nitrogen and water vapor; the entropy value of the mixed working fluid at the inlet and outlet of the air filter is obtained by looking up the table according to the working fluid components and state, and is expressed as:

[0039] S af =refpropm(′S′,′T′,T af ,′P′,P af ,′oxygen′,′nitrogen′,′water′,xaf )

[0040] S133: Calculate the working fluid at the inlet and outlet of the air filter Value; the total logistics of the mixed working medium flowing at the inlet and outlet of the air filter By physics ,Chemical ,move He Shi It consists of four parts and carries out Ignore the movement during analysis He Shi , that is, For physical ratio Chemical ratio The sum is calculated as follows:

[0041] Ex af =m af ·ex af

[0042]

[0043] Among them, Ex af The mixed working fluid at the inlet and outlet of the air filter value, m is the mass flow rate, ex is the mass flow ratio ,ex ph and ex ch Compared to physical Hebi Chemistry , H0 and S0 are the enthalpy and entropy of the inlet and outlet mixed working fluids under standard conditions, R is the universal gas constant, x i is the mole fraction, Standard chemical composition of the components .

[0044] Furthermore, step S2 specifically includes the following steps:

[0045] S21: Calculating the working fluid composition and working fluid state at the air compressor inlet; the mixed working fluid at the air compressor inlet includes oxygen, nitrogen and water vapor; the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working fluid at the air compressor inlet are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working fluid at the air filter outlet;

[0046] S22: Calculating the composition and state of the working fluid at the outlet of the air compressor; the mixed working fluid at the outlet of the air compressor includes oxygen, nitrogen, and water vapor; the function of the air compressor is to increase the pressure of the working fluid to the pressure required by the fuel cell stack operating conditions. During the compression process, the composition of the mixed working fluid remains unchanged, while the temperature increases;

[0047] The oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the air compressor outlet are the same as the oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the air compressor inlet;

[0048] The working fluid pressure at the air compressor outlet is the sum of the stack cathode inlet pressure, the intercooler flow resistance, and the humidifier dry side flow resistance, and is calculated as follows:

[0049] Air compressor outlet mixed working medium pressure = stack cathode inlet pressure + intercooler flow resistance + humidifier dry side flow resistance

[0050] According to the thermodynamic principles, the calculation formula for the mixed working medium temperature at the outlet of the air compressor is:

[0051]

[0052] Among them, T ac,out is the working medium temperature at the outlet of the air compressor, T ac,in is the mixed working medium temperature at the air compressor inlet, η ac is the isentropic efficiency of the air compressor, P ac,in and P ac,out are the pressures of the mixed working fluid at the inlet and outlet of the air compressor, respectively; γ is the specific heat ratio;

[0053] S23: Calculate the working fluid at the inlet and outlet of the air compressor Value; the air compressor Value calculation including logistics and energy flow Two parts, logistics The calculation method of the mixed working medium at the inlet and outlet of the air filter The calculation method of the value is the same, and the calculation formula is:

[0054] Ex ac =m ac ·ex ac

[0055] The calculation of the flow of working fluid at the inlet and outlet of the air compressor Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of air compressor Calculation: The enthalpy and entropy of the mixed working fluid at the inlet and outlet of the air compressor are obtained by looking up the table in the software according to the composition and state of the mixed working fluid, and are expressed as:

[0056] H ac =refpropm(′H′,′T′,T ac ,′P′,P ac ,′oxygen′,′nitrogen′,′water′,x ac )

[0057] Sac =refpropm(′S′,′T′,T ac ,′P′,P ac ,′oxygen′,′nitrogen′,′water′,x ac )

[0058] The logistics ratio of the mixed working medium at the inlet and outlet of the air compressor For physical ratio Chemical ratio The sum is calculated as follows:

[0059]

[0060] The air compressor When analyzing, consider the energy flow provided by the outside world to the air compressor , that is, the merit , whose value is equal to the work; the calculation formula for the work provided by the outside world to the air compressor is:

[0061]

[0062] Among them, W ac is the power consumed by the air compressor, C p,ac,in is the specific heat capacity of the mixed working fluid at the air compressor inlet.

[0063] Furthermore, step S3 specifically includes the following steps:

[0064] S31: Calculating the working fluid composition and working fluid state at the intercooler inlet; the mixed working fluid at the intercooler inlet includes oxygen, nitrogen and water vapor; the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working fluid at the intercooler inlet are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working fluid at the air compressor outlet;

[0065] S32: Calculating the composition and state of the working fluid at the outlet of the intercooler; the mixed working fluid at the outlet of the intercooler includes oxygen, nitrogen, and water vapor; the function of the intercooler is to reduce the temperature of the working fluid to the temperature required by the fuel cell stack operating conditions. During this process, the composition of the mixed working fluid remains unchanged, the temperature decreases, and the pressure of the mixed working fluid decreases accordingly;

[0066] The oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the intercooler outlet are the same as the oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the intercooler inlet;

[0067] The intercooler outlet mixed working medium temperature is the fuel cell cathode inlet mixed working medium temperature, wherein the calculation method assumes that the mixed working medium does not participate in heat exchange when passing through the humidifier;

[0068] The mixed working medium pressure at the intercooler outlet is the difference between the air compressor outlet pressure and the intercooler flow resistance, and the calculation formula is:

[0069] Intercooler outlet mixed working medium pressure = air compressor outlet pressure - intercooler flow resistance

[0070] S33: Calculate the working fluid at the inlet and outlet of the intercooler Value; The mixed working medium of the intercooler inlet and outlet Value for logistics The calculation and logistics The calculation method of the mixed working medium at the inlet and outlet of the air filter The calculation method of the value is the same, and the calculation formula is:

[0071] Ex ic =m ic ·ex ic

[0072] The calculation of the intercooler inlet and outlet working medium logistics Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of intercooler Calculation: The enthalpy and entropy of the mixed working fluid at the inlet and outlet of the intercooler are obtained by looking up the table according to the composition and state of the mixed working fluid, and are expressed as:

[0073] H ic =refpropm(′H′,′T′,T ic ,′P′,P ic ,′oxygen′ , ′nitrogen′,′water′,x ic )

[0074] S ic =refpropm(′S′,′T′,T ic ,′P′,P ic ,′oxygen′,′nitrogen′,′water′,x ic )

[0075] The logistics ratio of the mixed working medium at the inlet and outlet of the intercooler For physical ratio Chemical ratio The sum is calculated as follows:

[0076]

[0077] Further, step S4 specifically includes the following steps:

[0078] S41: Calculating the working medium composition and working medium state at the dry side inlet of the humidifier; the mixed working medium at the dry side inlet of the humidifier includes oxygen, nitrogen and water vapor; the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working medium at the dry side inlet of the humidifier are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working medium at the intercooler outlet;

[0079] S42: Calculate the working fluid composition and working fluid state at the dry side outlet of the humidifier; the mixed working fluid at the dry side outlet of the humidifier includes oxygen, nitrogen and water vapor; the oxygen flow rate and nitrogen flow rate at the dry side outlet of the humidifier are equal to the oxygen flow rate and nitrogen flow rate at the cathode inlet; the pressure and temperature state of the mixed working fluid are obtained from the operating conditions of the fuel cell; the water vapor flow rate is the water vapor flow rate contained in the operating conditions of the pressure, temperature and humidity of the fuel cell cathode inlet; the calculation formula is:

[0080]

[0081] in, is the water vapor flow rate at the dry side outlet of the humidifier, N ca,air is the flow rate of the mixed working medium of oxygen and nitrogen at the cathode inlet of the fuel cell, RH ca,in is the relative humidity at the cathode inlet, RH ca,in is the saturated steam pressure at the cathode inlet, P ca,in is the cathode inlet pressure, T ca,in is the cathode inlet temperature;

[0082] S43: Calculate the working fluid composition and working fluid state at the wet side inlet of the humidifier; the mixed working fluid at the wet side inlet of the humidifier includes oxygen, nitrogen, and water, wherein the water is in two states: water vapor and liquid water; the nitrogen flow rate at the wet side inlet of the humidifier is the same as the nitrogen flow rate at the cathode inlet of the fuel cell, and the oxygen flow rate is the oxygen flow rate at the cathode inlet of the fuel cell minus the oxygen flow rate consumed by the cathode, and the calculation formula is:

[0083]

[0084] in, is the oxygen flow rate at the wet side inlet of the humidifier, is the oxygen flow rate at the cathode outlet of the fuel cell;

[0085] The water flow rate at the wet side inlet of the humidifier is the water flow rate at the cathode outlet of the fuel cell, which includes the water flow rate entering the cathode of the fuel cell, the water flow rate generated by the fuel cell reaction, and the water flow rate transmitted through the proton exchange membrane. The calculation formula is:

[0086] Humidifier wet side inlet water flow = fuel cell cathode outlet water flow = water flow entering the fuel cell cathode + water flow generated by the fuel cell reaction + water flow transmitted through the proton exchange membrane

[0087] The water flow rate generated by the fuel cell reaction is the water generated by the reaction between the oxygen at the cathode and the protons transferred from the anode through the proton exchange membrane and the electrons transferred from the external circuit. The calculation formula is:

[0088]

[0089] in, the flow of water generated for the fuel cell cathode;

[0090] The water flow rate transmitted by the proton exchange membrane mainly considers two transmission mechanisms: electroosmotic drag and concentration diffusion. The calculation formula is:

[0091]

[0092] λ=0.043+17.18RH-39.85RH 2 +36RH 3

[0093]

[0094] in, is the water flow through the proton exchange membrane, n d is the electroosmotic drag coefficient, D mw is the water vapor diffusion coefficient in the proton exchange membrane, L is the thickness of the proton exchange membrane, and are the densities of the anode and cathode water, L ca and L an are the thickness of cathode and anode respectively, Deffa ca and Deff an are the effective binary diffusion coefficients of the anode and cathode, is the water vapor flow rate at the anode inlet, is the hydrogen flow rate at the anode inlet, is the molar mass of hydrogen, RH an is the relative humidity of the anode, P an,in is the anode inlet pressure, is the saturated vapor pressure at the anode inlet, is the hydrogen stoichiometric ratio, T an,in is the anode inlet temperature, λ is the water content of the proton exchange membrane, and RH is the relative humidity of the proton exchange membrane;

[0095] The water flow at the wet side inlet of the humidifier includes water vapor flow and liquid water flow. The water vapor flow is the saturated water vapor flow under the operating conditions of the fuel cell cathode outlet pressure and temperature. The calculation formula is:

[0096]

[0097]

[0098] in, is the water vapor flow rate at the wet side inlet of the humidifier, is the water vapor flow rate at the cathode outlet of the fuel cell, M air,ca is the molar mass of the mixed working fluid of oxygen and nitrogen at the cathode outlet, is the saturated vapor pressure at the cathode outlet, P ca,out is the cathode outlet pressure, T ca,out is the cathode outlet temperature;

[0099] The temperature and pressure of the mixed working fluid at the wet side inlet of the humidifier are the temperature and pressure of the mixed working fluid at the cathode outlet of the fuel cell, which are obtained from the operating conditions of the fuel cell;

[0100] S44: Calculate the working fluid components and working fluid state at the wet side outlet of the humidifier; the mixed working fluid at the wet side outlet of the humidifier includes oxygen, nitrogen and water, wherein the water is in two states: water vapor and liquid water; the oxygen and nitrogen flow rates at the wet side outlet of the humidifier are the same as the oxygen and nitrogen flow rates at the wet side inlet of the humidifier, and the temperature of the mixed working fluid is also the same; the pressure of the mixed working fluid at the wet side outlet of the humidifier is the difference between the wet side inlet pressure of the humidifier and the wet side flow resistance of the humidifier, and the calculation formula is:

[0101] The pressure of the mixed working fluid at the wet side outlet of the humidifier = the inlet pressure of the wet side of the humidifier - the flow resistance of the wet side of the humidifier

[0102] The water flow rate at the wet side outlet of the humidifier is the difference between the water flow rate at the wet side inlet of the humidifier and the water flow rate used to humidify the dry side air. The calculation formula is:

[0103] Humidifier wet side outlet water flow = humidifier wet side inlet water flow - water flow used to humidify dry side air

[0104] The water flow rate for humidifying the dry side air is determined by the water vapor flow rate at the intercooler outlet and the humidifier dry side outlet, and the calculation formula is:

[0105] Water flow rate used to humidify dry side air = water vapor flow rate at dry side outlet of humidifier - water vapor flow rate at intercooler outlet

[0106] The water flow at the wet side outlet of the humidifier includes water vapor flow and liquid water flow. The water vapor flow is the saturated water vapor flow under the pressure and temperature operating conditions of the wet side outlet of the humidifier. The calculation formula is:

[0107]

[0108] in, is the water vapor flow rate at the wet side outlet of the humidifier, is the saturated vapor pressure at the wet side outlet of the humidifier, P hu,humid,out is the wet side outlet pressure of the humidifier, T hu,humid,out is the wet side outlet temperature of the humidifier;

[0109] S45: Calculate the working fluid at the inlet and outlet of the humidifier Value; the mixed working medium of the humidifier inlet and outlet Value for logistics The calculation and logistics The calculation method of the mixed working fluid at the inlet and outlet of the intercooler The calculation method of the value is the same, but it is necessary to consider the calculation difference of water in different existence states in the mixed working fluid. The calculation formula is:

[0110] Ex hu =m hu ·ex hu

[0111] The logistics of the mixed working medium at the inlet and outlet of the humidifier are calculated Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of humidifier Calculation: The enthalpy and entropy of the mixed working fluid at the inlet and outlet of the humidifier are the average values ​​of the enthalpy and entropy of the gaseous working fluid and the liquid working fluid, and the calculation formula is:

[0112] H hu =(H hu,gas ×N hu,gas +H hu,liquid ×N hu,liquid ) / N hu

[0113] S hu =(S hu,gas ×N hu,gas +S hu,liquid ×N hu,liquid ) / N hu

[0114] The enthalpy and entropy of the gaseous working medium are obtained by looking up the table according to the working medium composition and working medium state, and are expressed as:

[0115] H hu,gas =refpropm(′H′,′T′,T hu ,′P′,P hu ,′oxygen′,′nitrogen′,′water′,x hu,gas )

[0116] S hu,gas =refpropm(′S′,′T′,T hu ,′P′,P hu,′oxygen′,′nitrogen′,′water′,x hu,gas )

[0117] The liquid working medium is liquid water, and its enthalpy and entropy values ​​are obtained by looking up the table and expressed as:

[0118] H hu,liquid =refpropm(′H′,′T′,T hu ,′Q′,0,′water′)

[0119] S hu,liquid =refpropm(′S′,′T′,T hu ,′Q′,0,′water′)

[0120] The logistics ratio of the mixed working medium at the inlet and outlet of the humidifier For physical ratio Chemical ratio The sum is calculated as follows:

[0121]

[0122] Furthermore, step S5 specifically includes the following steps:

[0123] S51: Calculate air filter Loss and Efficiency of the air filter The loss is the mixed working fluid at the air filter inlet Value and outlet mixed working fluid The difference between the values ​​is calculated as:

[0124] Ex D,af =Ex af,in -Ex af,out

[0125] Among them, Ex D,af For air filter Loss, Ex af,in and Ex af,out The mixed working fluid at the inlet and outlet of the air filter value;

[0126] The air filter Efficiency as product and fuel The ratio of the mixed working fluid at the air filter outlet and inlet The ratio of the values ​​is calculated as:

[0127]

[0128] Among them, η ex,af For air filter Efficiency, Ex P,i The product of the jth component ,Ex F,i is the fuel of the jth component ;

[0129] S52: Calculate the air compressor Loss and efficiency of the air compressor; The loss is the mixed working fluid at the inlet of the air compressor The sum of the value and the parasitic power consumed by the air compressor and the mixed working medium at the outlet of the air compressor The difference between the values ​​is calculated as:

[0130] Ex D,ac =Ex ac,in -Ex ac,out +W ac

[0131] The air compressor Efficiency as product and fuel The ratio of the mixed working fluid at the outlet and inlet of the air compressor The ratio of the value to the sum of the parasitic power consumed by the air compressor is calculated as:

[0132]

[0133] S53: Calculate intercooler Loss and efficiency of the intercooler; The loss is the mixed working fluid at the intercooler inlet Value and outlet mixed working fluid The difference between the values ​​is calculated as:

[0134] Ex D,ic =Ex ic,in -Ex ic,out

[0135] The intercooler Efficiency as product and fuel The ratio of the intercooler outlet and inlet mixed working fluid The ratio of the values ​​is calculated as:

[0136]

[0137] S54: Computational humidifier Loss and Efficiency of the humidifier The loss is the mixed working fluid at the humidifier inlet Value and outlet mixed working fluid The difference between the values, where the inlet and outlet include the four inlets and outlets on the dry side and wet side of the humidifier respectively, is calculated as follows:

[0138] Ex D,hu =Ex hu,dry,in +Ex hu , humid,in -Ex hu,dry,out -Ex hu , humid,out

[0139] The humidifier Efficiency as product and fuel The ratio of the mixed working fluid at the humidifier outlet and inlet The ratio of the values ​​is calculated as:

[0140]

[0141] S55: Calculation of fuel cell air system Loss and efficiency of the fuel cell air system; Losses for various components of the air system The sum of the losses is calculated as:

[0142] Ex D,system,ari =∑Ex D,j =Ex D,af +Ex D,ac +Ex D,ic +Ex D,hu

[0143] The fuel cell air system Efficiency as product and fuel The ratio of the mixed working medium at the outlet of the air system Value and inlet mixed medium The ratio of the value to the sum of the system parasitic power consumption is calculated as:

[0144]

[0145] The beneficial effects of the present invention are as follows: the fuel cell air system evaluation method proposed in the present invention improves the accuracy and efficiency of energy consumption evaluation in the fuel cell air system; by calculating the mixed working fluid components and states of each node in the fuel cell air system, the state parameters of the fluids in each part of the system are obtained to As a system evaluation parameter, quantitative analysis of system energy efficiency loss; from the perspective of "quality", the distribution of energy flow in the system is revealed. Analyze theory and develop Loss, efficiency theoretical calculation and simulation research, revealing the system mass energy flow, Dissipation and energy consumption laws, deepen the understanding of the complex thermal-fluid coupling phenomenon of the fuel cell air system, and help achieve the goal of optimizing the efficiency and energy consumption of the fuel cell air system.

[0146] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0147] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0148] Figure 1 The present invention is based on Schematic flow chart of the fuel cell air system evaluation method. DETAILED DESCRIPTION

[0149] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0150] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0151] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring the embodiments of the present invention.

[0152] Example 1:

[0153] The present invention provides a A fuel cell air system evaluation method comprising the following steps:

[0154] S1: Calculate the working fluid at the inlet and outlet of the air filter Value; Step S1 comprises the following steps:

[0155] S11: Calculate the working fluid composition and working fluid state at the air filter inlet; Step S11 specifically includes the following steps:

[0156] S111: Calculate the oxygen (O2) flow rate at the air filter inlet; the oxygen flow rate at the air filter inlet is obtained by theoretical calculation based on the operating conditions of the fuel cell stack, and its size is equal to the oxygen flow rate at the cathode inlet. The calculation formula is:

[0157]

[0158] in, is the oxygen flow rate at the air filter inlet (g / s), is the oxygen flow rate at the cathode inlet of the stack (g / s), is the peroxygen ratio, is the molar mass of oxygen (g / mol), N is the number of cells in the stack, I cell is the working current density of the stack (A / cm 2 ), A cell is the activation area of ​​the battery stack (cm 2 ), F is the Faraday constant (96485C / mol);

[0159] S112: Calculate the nitrogen (N2) flow rate at the air filter inlet; the ratio of nitrogen flow rate to oxygen flow rate at the air filter inlet is 0.79:0.21, and the calculation formula is,

[0160]

[0161] in, is the oxygen flow rate at the air filter inlet (g / s), is the nitrogen flow rate at the cathode inlet of the stack (g / s);

[0162] S113: Calculate the water vapor flow rate at the air filter inlet; the water vapor flow rate at the air filter inlet is the saturated water vapor flow rate contained in the air, where the relative humidity of the air is 50%, and the calculation formula is,

[0163]

[0164] in, is the water vapor flow rate at the air filter inlet (g / s), Naf,air is the flow rate of the mixed working medium of oxygen and nitrogen at the air filter inlet (g / s), is the molar mass of water (g / mol), M air is the molar mass of the mixed working medium of oxygen and nitrogen at the air filter inlet (g / mol), RH air is the relative humidity of the air, is the saturated steam pressure (Pa) at the air filter inlet, which can be obtained by looking up the table using Refprop software. af,in is the air filter inlet pressure (Pa); and are the molar masses of nitrogen and oxygen, respectively (g / mol);

[0165] S114: Calculating the working medium state at the air filter inlet; the temperature and pressure state of the mixed working medium at the air filter inlet are the same as the temperature and pressure state of the air;

[0166] S12: Calculate the working fluid composition and working fluid state at the air filter outlet; Step S12 specifically includes the following steps:

[0167] S121: Calculating the working fluid composition at the air filter outlet; the mixed working fluid composition at the air filter outlet is the same as the mixed working fluid composition at the air filter inlet;

[0168] S122: Calculate the working medium state at the air filter outlet; the air filter mixed working medium temperature is the same as the air filter inlet temperature, and the mixed working medium pressure is the difference between the atmospheric pressure and the air filter mixed working medium flow resistance. The calculation formula is: air filter outlet pressure = air filter inlet pressure - air filter flow resistance;

[0169] S13: Calculate the working fluid at the inlet and outlet of the air filter Step S13 specifically includes the following steps:

[0170] S131: Calculate the enthalpy of the working fluid at the inlet and outlet of the air filter; the enthalpy of the mixed working fluid at the inlet and outlet of the air filter is obtained by looking up the table with the Refprop software according to the components and state of the mixed working fluid. The code entered in Matlab is:

[0171] H af =refpropm(′H′,′T′,T af ,′P′,P af ,′oxygen′,′nitrogen′,′water′,x af )

[0172] Among them, T af is the temperature corresponding to the air filter inlet or outlet, P af is the pressure corresponding to the air filter inlet or outlet, x afThe mixed working fluid components corresponding to the air filter inlet or outlet;

[0173] S132: Calculate the entropy value of the working fluid at the inlet and outlet of the air filter; the mixed working fluid at the inlet and outlet of the air filter includes oxygen, nitrogen and water vapor. The entropy value of the mixed working fluid at the inlet and outlet of the air filter is obtained by looking up the table using Refprop software based on the working fluid components and state. The code entered in Matlab is:

[0174] S af =refpropm(′S′,′T′,T af ,′P′,P af ,′oxygen′,′nintrogen′,′water′,x af )

[0175] S133: Calculate the working fluid at the inlet and outlet of the air filter Value; the total logistics of the mixed working medium flowing at the inlet and outlet of the air filter By physics ,Chemical ,move He Shi The present invention is composed of four parts, and it is carried out for thermodynamic system Ignore the movement in the analysis He Shi , that is, For physical ratio Chemical ratio The sum of , is calculated as,

[0176] Ex af =m af ·ex af

[0177]

[0178] Among them, Ex af The mixed working fluid at the inlet and outlet of the air filter value (W), m is the mass flow rate (g / s), ex is the mass flow ratio (J / g), ex ph and ex ch Compared to physical Hebi Chemistry , H0 and S0 are the enthalpy and entropy of the inlet and outlet mixed working fluids under standard conditions (T0 = 298.15K, P0 = 1atm), R is the universal gas constant (J / mol / K), x i is the mole fraction, Standard chemical composition of the components (J / mol);

[0179] S2: Calculate the working fluid at the inlet and outlet of the air compressor Value; Step S2 comprises the following steps:

[0180] S21: Calculating the composition and state of the working fluid at the air compressor inlet; the mixed working fluid at the air compressor inlet includes oxygen, nitrogen, and water vapor. The oxygen flow rate, nitrogen flow rate, water vapor flow rate, and pressure and temperature of the mixed working fluid at the air compressor inlet are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate, and pressure and temperature of the mixed working fluid at the air filter outlet.

[0181] S22: Calculate the composition and state of the working fluid at the outlet of the air compressor. The mixed working fluid at the outlet of the air compressor includes oxygen, nitrogen, and water vapor. The function of the air compressor is to increase the pressure of the working fluid to the pressure required by the fuel cell stack operating conditions. During the compression process, the composition of the mixed working fluid remains unchanged, while the temperature increases.

[0182] The oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the air compressor outlet are the same as the oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the air compressor inlet.

[0183] The working fluid pressure at the outlet of the air compressor is the sum of the cathode inlet pressure of the stack, the flow resistance of the intercooler, and the dry side flow resistance of the humidifier. The calculation formula is: the mixed working fluid pressure at the outlet of the air compressor = the cathode inlet pressure of the stack + the flow resistance of the intercooler + the dry side flow resistance of the humidifier.

[0184] According to the principles of thermodynamics, when the working fluid is compressed, the outside world does work on the working fluid, and the internal energy of the working fluid increases, resulting in an increase in temperature. The calculation formula for the mixed working fluid temperature at the outlet of the air compressor is:

[0185]

[0186] Among them, T ac,out is the working medium temperature at the outlet of the air compressor (K), T ac,in is the mixed working medium temperature at the air compressor inlet (K), η ac is the isentropic efficiency of the air compressor, P ac,in and P ac,out are the pressures of the mixed working fluid at the inlet and outlet of the air compressor (Pa), and γ is the specific heat ratio.

[0187] S23: Calculate the working fluid at the inlet and outlet of the air compressor Value; the air compressor Value calculation including logistics and energy flow Two parts, logistics The calculation method of the mixed working medium at the inlet and outlet of the air filter The calculation method of the value is the same, the calculation formula is:

[0188] Ex ac =m ac ·ex ac

[0189] The calculation of the flow of working fluid at the inlet and outlet of the air compressor Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of air compressor Calculation: The enthalpy and entropy of the mixed working fluid at the inlet and outlet of the air compressor are obtained by looking up the table with Refprop software according to the mixed working fluid components and state. The code is entered in Matlab as follows:

[0190] H ac =refpropm(′H′,′T′,T ac ,′P′,P ac ,′oxygen′,′nitrogen′,′water′,x ac )

[0191] S ac =refpropm(′S′,′T′,T ac ,′P′,P ac ,′oxygen′,′nitrogen′,′water′,x ac )

[0192] The logistics ratio of the mixed working medium at the inlet and outlet of the air compressor For physical ratio Chemical ratio The sum of , is calculated as,

[0193]

[0194] The air compressor When analyzing, the energy flow provided by the outside world to the air compressor should also be considered. , that is, the merit , its value is equal to work (Ex = W); the calculation formula for the work provided by the outside world to the air compressor is,

[0195]

[0196] Among them, W ac is the power consumed by the air compressor (W), C p,ac,in is the specific heat capacity of the mixed working fluid at the air compressor inlet (J / (kg·K)).

[0197] S3: Calculate the working fluid at the inlet and outlet of the intercooler Value; Step S3 comprises the following steps:

[0198] S31: Calculating the composition and state of the working fluid at the intercooler inlet; the mixed working fluid at the intercooler inlet includes oxygen, nitrogen, and water vapor. The oxygen flow rate, nitrogen flow rate, water vapor flow rate, and pressure and temperature state of the mixed working fluid at the intercooler inlet are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate, and pressure and temperature state of the mixed working fluid at the air compressor outlet.

[0199] S32: Calculate the composition and state of the working fluid at the intercooler outlet. The intercooler outlet mixed working fluid includes oxygen, nitrogen, and water vapor. The intercooler cools the working fluid to the temperature required for stack operation. During this process, the composition of the mixed working fluid remains unchanged while the temperature decreases. Due to the resistance of the intercooler, the pressure of the mixed working fluid also decreases.

[0200] The oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the intercooler outlet are the same as the oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the intercooler inlet.

[0201] The mixed working medium temperature at the outlet of the intercooler is the mixed working medium temperature at the cathode inlet of the fuel cell, wherein the calculation method assumes that the mixed working medium does not participate in heat exchange when passing through the humidifier.

[0202] The mixed working medium pressure at the intercooler outlet is the difference between the air compressor outlet pressure and the intercooler flow resistance, and is calculated as follows: mixed working medium pressure at the intercooler outlet = air compressor outlet pressure - intercooler flow resistance;

[0203] S33: Calculate the working fluid at the inlet and outlet of the intercooler Value; the mixed working medium at the inlet and outlet of the intercooler Value for logistics The calculation and logistics The calculation method of the mixed working medium at the inlet and outlet of the air filter The calculation method of the value is the same, the calculation formula is:

[0204] Ex ic =m ic ·ex ic

[0205] The calculation of the intercooler inlet and outlet working medium logistics Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of intercooler Calculation: The enthalpy and entropy of the mixed working fluid at the inlet and outlet of the intercooler are obtained by looking up the table with the Refprop software according to the mixed working fluid composition and state. The code is entered in Matlab as follows:

[0206] H ic =refpropm(′H′,′T′,T ic ,′P′,P ic,′oxygen′,′nitrogen′,′water′,x ic )

[0207] S ic =refpropm(′S′,′T′,T ic ,′P′,P ic ,′oxygen′,′nitrogen′,′water′,x ic )

[0208] The logistics ratio of the mixed working medium at the inlet and outlet of the intercooler For physical ratio Chemical ratio The sum of , is calculated as,

[0209]

[0210] S4: Calculate the working fluid at the inlet and outlet of the humidifier Value; Step S4 comprises the following steps:

[0211] S41: Calculating the composition and state of the working fluid at the dry side inlet of the humidifier; the mixed working fluid at the dry side inlet of the humidifier includes oxygen, nitrogen, and water vapor. The oxygen flow rate, nitrogen flow rate, water vapor flow rate, and the pressure and temperature state of the mixed working fluid at the dry side inlet of the humidifier are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate, and the pressure and temperature state of the mixed working fluid at the intercooler outlet.

[0212] S42: Calculate the working fluid composition and working fluid state at the dry side outlet of the humidifier; the mixed working fluid at the dry side outlet of the humidifier includes oxygen, nitrogen, and water vapor. The oxygen flow rate and nitrogen flow rate at the dry side outlet of the humidifier are equal to the oxygen flow rate and nitrogen flow rate at the cathode inlet. The pressure and temperature state of the mixed working fluid are obtained from the operating conditions of the fuel cell. The water vapor flow rate is the water vapor flow rate contained in the operating conditions of the pressure, temperature, and humidity of the fuel cell cathode inlet. The calculation formula is:

[0213]

[0214] in, is the water vapor flow rate at the dry side outlet of the humidifier (g / s), N ca,air is the flow rate of oxygen and nitrogen mixture at the cathode inlet of the fuel cell (g / s), RH ca,in is the relative humidity at the cathode inlet, RH ca,in is the saturated steam pressure at the cathode inlet (Pa), P ca,in is the cathode inlet pressure (Pa), T ca,in is the cathode inlet temperature (K).

[0215] S43: Calculate the working fluid composition and working fluid state at the wet side inlet of the humidifier; the mixed working fluid at the wet side inlet of the humidifier includes oxygen, nitrogen, and water, where the water is in two states: water vapor and liquid water. The nitrogen flow rate at the wet side inlet of the humidifier is the same as the nitrogen flow rate at the cathode inlet of the fuel cell, and the oxygen flow rate is the oxygen flow rate at the cathode inlet of the fuel cell minus the oxygen flow rate consumed by the cathode. The calculation formula is:

[0216]

[0217] in, is the oxygen flow rate at the wet side inlet of the humidifier (g / s), is the oxygen flow rate at the cathode outlet of the fuel cell (g / s).

[0218] The water flow at the wet side inlet of the humidifier is the water flow at the cathode outlet of the fuel cell, which includes the water flow entering the cathode of the fuel cell, the water flow generated by the fuel cell reaction and the water flow transmitted through the proton exchange membrane. The calculation formula is: water flow at the wet side inlet of the humidifier = water flow at the cathode outlet of the fuel cell = water flow entering the cathode of the fuel cell + water flow generated by the fuel cell reaction + water flow transmitted through the proton exchange membrane.

[0219] The water flow rate generated by the fuel cell reaction is the water generated by the reaction between the oxygen at the cathode and the protons transferred from the anode through the proton exchange membrane and the electrons transferred from the external circuit. The calculation formula is:

[0220]

[0221] in, The water flow generated for the fuel cell cathode.

[0222] The water flow rate transmitted by the proton exchange membrane mainly considers two transmission mechanisms: electroosmotic drag and concentration diffusion. The calculation formula is:

[0223]

[0224] λ=0.043+17.18RH-39.85RH 2 +36RH 3

[0225]

[0226] in, is the water flow rate through the proton exchange membrane (g / s), n d is the electroosmotic drag coefficient, D mw is the water vapor diffusion coefficient in the proton exchange membrane (m 2 / s), L is the thickness of the proton exchange membrane (mm), and The densities of the anode and cathode water (g / cm 3 ), L ca and L an Respectively, the thickness of the cathode and anode (mm), Deff ca and Deff an The effective binary diffusion coefficients of anode and cathode (cm 2 / s), is the water vapor flow rate at the anode inlet (g / s), is the hydrogen flow rate at the anode inlet (g / s), is the molar mass of hydrogen (g / mol), RH an is the relative humidity of the anode, P an,in is the anode inlet pressure (Pa), is the saturated vapor pressure at the anode inlet (Pa), is the hydrogen stoichiometric ratio, T an,in is the anode inlet temperature (K), λ is the water content of the proton exchange membrane, and RH is the relative humidity of the proton exchange membrane.

[0227] The water flow at the wet side inlet of the humidifier includes water vapor flow and liquid water flow. The water vapor flow is the saturated water vapor flow under the operating conditions of the fuel cell cathode outlet pressure and temperature. The calculation formula is:

[0228]

[0229] in, is the water vapor flow rate at the wet side inlet of the humidifier (g / s), is the water vapor flow rate at the cathode outlet of the fuel cell (g / s), M air,ca is the molar mass of the mixed working fluid of oxygen and nitrogen at the cathode outlet (g / mol), is the saturated vapor pressure at the cathode outlet (Pa), P ca,out is the cathode outlet pressure (Pa), T ca,out is the cathode outlet temperature (K).

[0230] The temperature and pressure of the mixed working fluid at the wet side inlet of the humidifier are the temperature and pressure of the mixed working fluid at the cathode outlet of the fuel cell, and are obtained from the operating conditions of the fuel cell.

[0231] S44: Calculating the working fluid composition and working fluid state at the wet side outlet of the humidifier; the mixed working fluid at the wet side outlet of the humidifier includes oxygen, nitrogen, and water, where the water is in two states: water vapor and liquid water. The oxygen and nitrogen flow rates at the wet side outlet of the humidifier are the same as the oxygen and nitrogen flow rates at the wet side inlet of the humidifier, and the temperature of the mixed working fluid is also the same. The pressure of the mixed working fluid at the wet side outlet of the humidifier is the difference between the wet side inlet pressure of the humidifier and the wet side flow resistance of the humidifier. The calculation formula is: pressure of the mixed working fluid at the wet side outlet of the humidifier = pressure at the wet side inlet of the humidifier - wet side flow resistance of the humidifier.

[0232] The humidifier wet side outlet water flow is the difference between the humidifier wet side inlet water flow and the water flow used to humidify the dry side air. The calculation formula is: humidifier wet side outlet water flow = humidifier wet side inlet water flow - water flow used to humidify the dry side air.

[0233] The water flow rate for humidifying the dry side air is determined by the water vapor flow rates at the intercooler outlet and the humidifier dry side outlet, and is calculated as follows: water flow rate for humidifying the dry side air = water vapor flow rate at the humidifier dry side outlet - water vapor flow rate at the intercooler outlet.

[0234] The water flow at the wet side outlet of the humidifier includes water vapor flow and liquid water flow. The water vapor flow is the saturated water vapor flow under the pressure and temperature operating conditions of the wet side outlet of the humidifier. The calculation formula is:

[0235]

[0236] in, is the water vapor flow rate at the wet side outlet of the humidifier (g / s), is the saturated vapor pressure at the wet side outlet of the humidifier (Pa), P hu,humid,out is the outlet pressure of the wet side of the humidifier (Pa), T hu,humid,out is the wet side outlet temperature of the humidifier (K).

[0237] S45: Calculate the working fluid at the inlet and outlet of the humidifier Value; the mixed working medium of the humidifier inlet and outlet Value for logistics The calculation and logistics The calculation method of the mixed working fluid at the inlet and outlet of the intercooler The calculation method of the value is the same, but it is necessary to consider the calculation difference of water in the mixed working fluid in different states. The calculation formula is:

[0238] Ex hu =m hu ·ex hu

[0239] The logistics of the mixed working medium at the inlet and outlet of the humidifier are calculated Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of humidifier Calculation; the enthalpy and entropy of the mixed working fluid at the inlet and outlet of the humidifier are the average values ​​of the enthalpy and entropy of the gaseous working fluid and the liquid working fluid, and the calculation formula is,

[0240] H hu =(H hu,gas ×N hu,gas +H hu,liquid ×N hu,liquid ) / N hu

[0241] S hu =(S hu,gas ×N hu,gas +S hu,liquid ×N hu,liquid ) / N hu

[0242] The enthalpy and entropy of the gaseous working fluid are obtained by looking up the table with Refprop software according to the working fluid composition and working fluid state. The code entered in Matlab is:

[0243] H hu,gas =refpropm(′H′,′T′,T hu ,′P′,P hu ,′oxygen′,′nitrogen′,′water′,x hu,gas )

[0244] S hu,gas =refpropm(′S′,′T′,T hu ,′P′,P hu ,′oxygen′,′nitrogen′,′water′,x hu,gas )

[0245] The liquid working medium is liquid water, and its enthalpy and entropy values ​​are obtained by looking up the table with Refprop software. The code entered in Matlab is:

[0246] H hu,liquid =refpropm(′H′,′T′,T hu ,′Q′,0,′water′)

[0247] S hu,liquid =refpropm(′S′,′T′,T hu ,′Q′,0,′water′)

[0248] The logistics ratio of the mixed working medium at the inlet and outlet of the humidifier For physical ratio Chemical ratio The sum of , is calculated as,

[0249]

[0250] S5: According to the working fluid of the air filter, air compressor, intercooler and humidifier The values ​​of air filter, air compressor, intercooler and humidifier are obtained respectively. Loss and efficiency, and ultimately the fuel cell air system Loss and Efficiency. Step S5 includes the following steps:

[0251] S51: Calculate air filter Loss and Efficiency of the air filter The loss is the mixed working fluid at the air filter inlet Value and outlet mixed working fluid The difference between the values ​​is calculated as follows:

[0252] Ex D,af =Ex af,in -Ex af,out

[0253] Among them, Ex D,af For air filter Loss (W), Ex af,in and Ex af,out The mixed working fluid at the inlet and outlet of the air filter Value (W).

[0254] The air filter Efficiency as product and fuel The ratio of the mixed working fluid at the air filter outlet and inlet The ratio of the values ​​is calculated as follows:

[0255]

[0256] Among them, η ex,af For air filter Efficiency, Ex P,i The product of the jth component (W), Ex F,i is the fuel of the jth component (W).

[0257] S52: Calculate the air compressor Loss and efficiency of the air compressor; The loss is the mixed working fluid at the inlet of the air compressor The sum of the value and the parasitic power consumed by the air compressor and the mixed working medium at the outlet of the air compressor The difference between the values ​​is calculated as follows:

[0258] Ex D,ac =Ex ac,in -Ex ac,out +W ac

[0259] The air compressor Efficiency as product and fuel The ratio of the mixed working fluid at the outlet and inlet of the air compressor The ratio of the value to the sum of the parasitic power consumed by the air compressor is calculated as follows:

[0260]

[0261] S53: Calculate intercooler Loss and efficiency of the intercooler; The loss is the mixed working fluid at the intercooler inlet Value and outlet mixed working fluid The difference between the values ​​is calculated as follows:

[0262] Ex D,ic =Ex ic,in -Ex ic,out

[0263] The intercooler Efficiency as product and fuel The ratio of the intercooler outlet and inlet mixed working fluid The ratio of the values ​​is calculated as follows:

[0264]

[0265] S54: Computational humidifier Loss and Efficiency of the humidifier The loss is the mixed working fluid at the humidifier inlet Value and outlet mixed working fluid The difference between the values, where the inlet and outlet include the four inlets and outlets on the dry side and wet side of the humidifier respectively. The calculation formula is,

[0266] Ex D,hu =Ex hu,dry,in +Ex hu , humid,in -Ex hu,dry,out -Ex hu,xumid,out

[0267] The humidifier Efficiency as product and fuel The ratio of the mixed working fluid at the humidifier outlet and inlet The ratio of the values ​​is calculated as follows:

[0268]

[0269] S55: Calculation of fuel cell air system Loss and efficiency of the fuel cell air system; Losses for various components of the air system The sum of the losses is calculated as follows:

[0270] Ex D,system,air =∑Ex D,j =Ex D,af +Ex D,ac +Ex D,ic +Ex D,hu

[0271] The fuel cell air system Efficiency as product and fuel The ratio of the mixed working medium at the outlet of the air system Value and inlet mixed medium The ratio of the value to the sum of the system parasitic power consumption is calculated as follows:

[0272]

[0273] Example 2:

[0274] An electronic device comprising a memory and a processor;

[0275] The memory is used to store computer programs;

[0276] The processor is configured to implement the method described in Example 1 when executing the computer program.

[0277] Example 3:

[0278] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method described in Example 1 is implemented.

[0279] Example 4:

[0280] A computer program product includes a computer program, which implements the method described in embodiment 1 when executed by a processor.

[0281] In the above embodiments, references to "this embodiment" in the specification indicate that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least some embodiments, but not necessarily all embodiments. Multiple occurrences of "this embodiment" do not necessarily refer to the same embodiment.

[0282] In the above embodiments, although the invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those skilled in the art based on the foregoing description. For example, other memory structures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed. The embodiments of the present invention are intended to encompass all such alternatives, modifications, and variations that fall within the broad scope of the appended claims.

[0283] Regarding the computer-readable storage medium in this embodiment, those skilled in the art will appreciate that all or part of the steps in the aforementioned method embodiments can be implemented using hardware associated with the computer program. The aforementioned computer program can be stored in a computer-readable storage medium. When executed, the program performs the steps in the aforementioned method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0284] The electronic terminal provided in this embodiment includes a processor, a memory, a transceiver and a communication interface. The memory and the communication interface are connected to the processor and the transceiver and complete communication with each other. The memory is used to store computer programs, the communication interface is used for communication, and the processor and the transceiver are used to run computer programs so that the electronic terminal executes the various steps of the above method.

[0285] In this embodiment, the memory may include a random access memory (RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk storage.

[0286] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components.

[0287] The present invention can be used in a wide variety of general-purpose or special-purpose computing system environments or configurations, such as personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, and distributed computing environments that include any of the above.

[0288] The present invention may be described in the general context of computer-executable instructions, such as program modules, executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, and the like that perform specific tasks or implement specific abstract data types. The present invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media, including storage devices.

[0289] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method based on A fuel cell air system evaluation method, characterized in that: The following steps are involved: S1: Calculate the working fluid at the inlet and outlet of the air filter value; S2: Calculate the working fluid at the inlet and outlet of the air compressor value; S3: Calculate the working fluid at the inlet and outlet of the intercooler value; S4: Calculate the working fluid at the inlet and outlet of the humidifier value; S5: According to the working fluid of the air filter, air compressor, intercooler and humidifier The values ​​of air filter, air compressor, intercooler and humidifier are obtained respectively. Loss and efficiency, and ultimately the fuel cell air system Loss and efficiency.

2. The method according to claim 1 A fuel cell air system evaluation method, characterized in that: Step S1 specifically includes the following steps: S11: Calculate the working fluid composition and working fluid state at the air filter inlet; S12: Calculate the working fluid composition and working fluid state at the air filter outlet; S13: Calculate the working fluid at the inlet and outlet of the air filter value.

3. The method according to claim 2 A fuel cell air system evaluation method, characterized in that: Step S11 specifically includes the following steps: S111: Calculate the oxygen flow rate at the air filter inlet; the oxygen flow rate at the air filter inlet is obtained by theoretical calculation based on the operating conditions of the fuel cell stack, and its size is equal to the oxygen flow rate at the cathode inlet. The calculation formula is: in, is the oxygen flow rate at the air filter inlet, is the oxygen flow rate at the cathode inlet of the stack, is the peroxygen ratio, is the molar mass of oxygen, N is the number of cells in the stack, I cell is the working current density of the stack, A cell is the active area of ​​the battery stack cell, and F is the Faraday constant; S112: Calculate the nitrogen flow rate at the air filter inlet; the ratio of the nitrogen flow rate to the oxygen flow rate at the air filter inlet is 0.79:0.21, and the calculation formula is: in, is the oxygen flow rate at the air filter inlet, is the nitrogen flow rate at the cathode inlet of the stack; S113: Calculate the water vapor flow rate at the air filter inlet; the water vapor flow rate at the air filter inlet is the saturated water vapor flow rate contained in the air, where the relative humidity of the air is 50%, and the calculation formula is: in, is the water vapor flow rate at the air filter inlet, N af,air The flow rate of the mixed working medium of oxygen and nitrogen at the air filter inlet is the molar mass of water, M air is the molar mass of the mixed working medium of oxygen and nitrogen at the air filter inlet, RH air is the relative humidity of the air, is the saturated steam pressure at the air filter inlet, obtained by looking up the table using Refprop software; P af,in is the air filter inlet pressure; and are the molar masses of nitrogen and oxygen, respectively; S114: Calculating the working medium state at the air filter inlet; the temperature and pressure state of the mixed working medium at the air filter inlet are the same as the temperature and pressure state of the air.

4. The method according to claim 2 A fuel cell air system evaluation method, characterized in that: The step S12 specifically includes the following steps: S121: Calculating the working fluid composition at the air filter outlet; the mixed working fluid composition at the air filter outlet is the same as the mixed working fluid composition at the air filter inlet; S122: Calculate the working medium state at the air filter outlet; the mixed working medium temperature of the air filter is the same as the air filter inlet temperature, and the mixed working medium pressure is the difference between the atmospheric pressure and the flow resistance of the mixed working medium of the air filter. The calculation formula is: Air filter outlet pressure = air filter inlet pressure - air filter flow resistance.

5. The method according to claim 2 A fuel cell air system evaluation method, characterized in that: The step S13 specifically includes the following steps: S131: Calculate the enthalpy of the working fluid at the inlet and outlet of the air filter; the enthalpy of the mixed working fluid at the inlet and outlet of the air filter is obtained by looking up the table according to the composition and state of the mixed working fluid, and is expressed as: H af =refpropm(′H′,′T′,T af ,′P′,P af ,′oxygen′,′nitrogen′,′water′,x af ) Among them, T af is the temperature corresponding to the air filter inlet or outlet, P af is the pressure corresponding to the air filter inlet or outlet, x af The mixed working fluid components corresponding to the air filter inlet or outlet; S132: Calculate the entropy value of the working fluid at the inlet and outlet of the air filter; the mixed working fluid at the inlet and outlet of the air filter includes oxygen, nitrogen and water vapor; the entropy value of the mixed working fluid at the inlet and outlet of the air filter is obtained by looking up the table according to the working fluid components and state, and is expressed as: S af =refpropm(′S′,′T′,T af ,′P′,P af ,′oxygen′,′nitrogen′,′water′,x af ) S133: Calculate the working fluid at the inlet and outlet of the air filter Value; the total logistics of the mixed working medium flowing at the inlet and outlet of the air filter By physics ,Chemical ,move He Shi It consists of four parts and carries out Ignore the movement during analysis He Shi That is, For physical ratio Chemical ratio The sum is calculated as follows: Ex af =m af ·ex af Among them, Ex af The mixed working fluid at the inlet and outlet of the air filter value, m is the mass flow rate, ex is the mass flow ratio ex ph and ex ch Compared to physical Hebi Chemistry H0 and S0 are the enthalpy and entropy values ​​of the inlet and outlet mixed working fluids under standard conditions, R is the universal gas constant, and x i is the mole fraction, Standard chemical composition of the components 6. The method according to claim 1 A fuel cell air system evaluation method, characterized in that: Step S2 specifically includes the following steps: S21: Calculating the working fluid composition and working fluid state at the air compressor inlet; the mixed working fluid at the air compressor inlet includes oxygen, nitrogen and water vapor; the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working fluid at the air compressor inlet are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working fluid at the air filter outlet; S22: Calculating the composition and state of the working fluid at the outlet of the air compressor; the mixed working fluid at the outlet of the air compressor includes oxygen, nitrogen, and water vapor; the function of the air compressor is to increase the pressure of the working fluid to the pressure required by the fuel cell stack operating conditions. During the compression process, the composition of the mixed working fluid remains unchanged, while the temperature increases; The oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the air compressor outlet are the same as the oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the air compressor inlet; The working medium pressure at the air compressor outlet is the sum of the stack cathode inlet pressure, the intercooler flow resistance, and the humidifier dry side flow resistance, and is calculated as follows: Air compressor outlet mixed working medium pressure = stack cathode inlet pressure + intercooler flow resistance + humidifier dry side flow resistance According to the principles of thermodynamics, the calculation formula for the air compressor outlet mixed working medium temperature is: Among them, T ac,out is the working medium temperature at the outlet of the air compressor, T ac,in is the mixed working medium temperature at the air compressor inlet, η ac is the isentropic efficiency of the air compressor, P ac,in and P ac,out are the pressures of the mixed working fluid at the inlet and outlet of the air compressor, respectively; γ is the specific heat ratio; S23: Calculate the working fluid at the inlet and outlet of the air compressor Value; the air compressor Value calculation including logistics and energy flow Two parts, logistics The calculation method of the mixed working medium at the inlet and outlet of the air filter The calculation method of the value is the same, and the calculation formula is: Ex ac =m ac ·ex ac The calculation of the flow of working fluid at the inlet and outlet of the air compressor Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of air compressor Calculation: The enthalpy and entropy of the mixed working fluid at the inlet and outlet of the air compressor are obtained by looking up the table in the software according to the composition and state of the mixed working fluid, and are expressed as: H ac =refpropm(′H′,′T′,T ac ,′P′,P ac ,′oxygen′,′nitrogen′,′water′,x ac ) S ac =refpropm(′S′,′T′,T ac ,′P′,P ac ,′oxygen′,′nitrogen′,′water′,x ac ) The logistics ratio of the mixed working medium at the inlet and outlet of the air compressor For physical ratio Chemical ratio The sum is calculated as follows: The air compressor When analyzing, consider the energy flow provided by the outside world to the air compressor That is, the merit Its value is equal to the work; the calculation formula for the work provided by the outside world to the air compressor is: Among them, W ac is the power consumed by the air compressor, C p,ac,in is the specific heat capacity of the mixed working fluid at the air compressor inlet.

7. The method according to claim 1 A fuel cell air system evaluation method, characterized in that: Step S3 specifically includes the following steps: S31: Calculating the working fluid composition and working fluid state at the intercooler inlet; the mixed working fluid at the intercooler inlet includes oxygen, nitrogen and water vapor; the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working fluid at the intercooler inlet are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working fluid at the air compressor outlet; S32: Calculating the composition and state of the working fluid at the outlet of the intercooler; the mixed working fluid at the outlet of the intercooler includes oxygen, nitrogen, and water vapor; the function of the intercooler is to reduce the temperature of the working fluid to the temperature required by the fuel cell stack operating conditions. During this process, the composition of the mixed working fluid remains unchanged, the temperature decreases, and the pressure of the mixed working fluid decreases accordingly; The oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the intercooler outlet are the same as the oxygen flow rate, nitrogen flow rate, and water vapor flow rate at the intercooler inlet; The intercooler outlet mixed working medium temperature is the fuel cell cathode inlet mixed working medium temperature, wherein the calculation method assumes that the mixed working medium does not participate in heat exchange when passing through the humidifier; The mixed working medium pressure at the intercooler outlet is the difference between the air compressor outlet pressure and the intercooler flow resistance, and the calculation formula is: Intercooler outlet mixed working medium pressure = air compressor outlet pressure - intercooler flow resistance S33: Calculate the working fluid at the inlet and outlet of the intercooler Value; The mixed working medium of the intercooler inlet and outlet Value for logistics The calculation and logistics The calculation method of the mixed working medium at the inlet and outlet of the air filter The calculation method of the value is the same, and the calculation formula is: Ex ic =m ic ·ex ic The calculation of the intercooler inlet and outlet working medium logistics Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of intercooler Calculation: The enthalpy and entropy of the mixed working fluid at the inlet and outlet of the intercooler are obtained by looking up the table according to the composition and state of the mixed working fluid, and are expressed as: H ic =refpropm(′H′,′T′,T ic ,′P′,P ic ,′oxygen′,′nitrogen′,′water′,x ic ) S ic =refpropm(′S′,′T′,T ic ,′P′,P ic ,′oxygen′,′nitrogen′,′water′,x ic ) The flow ratio of the mixed working medium at the inlet and outlet of the intercooler For physical ratio Chemical ratio The sum is calculated as follows:

8. The method according to claim 1 A fuel cell air system evaluation method, characterized in that: Step S4 specifically includes the following steps: S41: Calculating the working medium composition and working medium state at the dry side inlet of the humidifier; the mixed working medium at the dry side inlet of the humidifier includes oxygen, nitrogen and water vapor; the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working medium at the dry side inlet of the humidifier are the same as the oxygen flow rate, nitrogen flow rate, water vapor flow rate and pressure and temperature state of the mixed working medium at the intercooler outlet; S42: Calculate the working fluid composition and working fluid state at the dry side outlet of the humidifier; the mixed working fluid at the dry side outlet of the humidifier includes oxygen, nitrogen and water vapor; the oxygen flow rate and nitrogen flow rate at the dry side outlet of the humidifier are equal to the oxygen flow rate and nitrogen flow rate at the cathode inlet; the pressure and temperature state of the mixed working fluid are obtained from the operating conditions of the fuel cell; the water vapor flow rate is the water vapor flow rate contained in the operating conditions of the pressure, temperature and humidity of the fuel cell cathode inlet; the calculation formula is: in, is the water vapor flow rate at the dry side outlet of the humidifier, N ca,air is the flow rate of the mixed working medium of oxygen and nitrogen at the cathode inlet of the fuel cell, RH ca,in is the relative humidity at the cathode inlet, RH ca,in is the saturated steam pressure at the cathode inlet, P ca,in is the cathode inlet pressure, T ca,in is the cathode inlet temperature; S43: Calculate the working fluid composition and working fluid state at the wet side inlet of the humidifier; the mixed working fluid at the wet side inlet of the humidifier includes oxygen, nitrogen, and water, wherein the water is in two states: water vapor and liquid water; the nitrogen flow rate at the wet side inlet of the humidifier is the same as the nitrogen flow rate at the cathode inlet of the fuel cell, and the oxygen flow rate is the oxygen flow rate at the cathode inlet of the fuel cell minus the oxygen flow rate consumed by the cathode, and the calculation formula is: in, is the oxygen flow rate at the wet side inlet of the humidifier, is the oxygen flow rate at the cathode outlet of the fuel cell; The water flow rate at the wet side inlet of the humidifier is the water flow rate at the cathode outlet of the fuel cell, which includes the water flow rate entering the cathode of the fuel cell, the water flow rate generated by the fuel cell reaction, and the water flow rate transmitted through the proton exchange membrane. The calculation formula is: Humidifier wet side inlet water flow = fuel cell cathode outlet water flow = water flow entering the fuel cell cathode + water flow generated by the fuel cell reaction + water flow transmitted through the proton exchange membrane The water flow rate generated by the fuel cell reaction is the water generated by the reaction between the oxygen at the cathode and the protons transferred from the anode through the proton exchange membrane and the electrons transferred from the external circuit. The calculation formula is: in, the flow of water generated for the fuel cell cathode; The water flow rate transmitted by the proton exchange membrane mainly considers two transmission mechanisms: electroosmotic drag and concentration diffusion. The calculation formula is: in, is the water flow through the proton exchange membrane, n d is the electroosmotic drag coefficient, D mw is the water vapor diffusion coefficient in the proton exchange membrane, L is the thickness of the proton exchange membrane, and are the densities of the anode and cathode water, L c x and L an are the thickness of cathode and anode, Deff ca and Deff an are the effective binary diffusion coefficients of the anode and cathode, is the water vapor flow rate at the anode inlet, is the hydrogen flow rate at the anode inlet, is the molar mass of hydrogen, RH an is the relative humidity of the anode, P an,in is the anode inlet pressure, is the saturated vapor pressure at the anode inlet, is the hydrogen stoichiometric ratio, T an,in is the anode inlet temperature, λ is the water content of the proton exchange membrane, and RH is the relative humidity of the proton exchange membrane; The water flow at the wet side inlet of the humidifier includes water vapor flow and liquid water flow. The water vapor flow is the saturated water vapor flow under the operating conditions of the fuel cell cathode outlet pressure and temperature. The calculation formula is: in, is the water vapor flow rate at the wet side inlet of the humidifier, is the water vapor flow rate at the cathode outlet of the fuel cell, M air,ca is the molar mass of the mixed working fluid of oxygen and nitrogen at the cathode outlet, is the saturated vapor pressure at the cathode outlet, P ca,out is the cathode outlet pressure, T ca,out is the cathode outlet temperature; The temperature and pressure of the mixed working fluid at the wet side inlet of the humidifier are the temperature and pressure of the mixed working fluid at the cathode outlet of the fuel cell, which are obtained from the operating conditions of the fuel cell; S44: Calculate the working fluid components and working fluid state at the wet side outlet of the humidifier; the mixed working fluid at the wet side outlet of the humidifier includes oxygen, nitrogen and water, wherein the water is in two states: water vapor and liquid water; the oxygen and nitrogen flow rates at the wet side outlet of the humidifier are the same as the oxygen and nitrogen flow rates at the wet side inlet of the humidifier, and the temperature of the mixed working fluid is also the same; the pressure of the mixed working fluid at the wet side outlet of the humidifier is the difference between the wet side inlet pressure of the humidifier and the wet side flow resistance of the humidifier, and the calculation formula is: The pressure of the mixed working fluid at the wet side outlet of the humidifier = the inlet pressure of the wet side of the humidifier - the flow resistance of the wet side of the humidifier The water flow rate at the wet side outlet of the humidifier is the difference between the water flow rate at the wet side inlet of the humidifier and the water flow rate used to humidify the dry side air. The calculation formula is: Humidifier wet side outlet water flow = humidifier wet side inlet water flow - water flow used to humidify dry side air The water flow rate for humidifying the dry side air is determined by the water vapor flow rate at the intercooler outlet and the humidifier dry side outlet, and the calculation formula is: Water flow rate for humidifying dry-side air = water vapor flow rate at humidifier dry-side outlet - water vapor flow rate at intercooler outlet. The water flow rate at the humidifier wet-side outlet includes water vapor flow rate and liquid water flow rate. The water vapor flow rate is the saturated water vapor flow rate under the pressure and temperature operating conditions at the humidifier wet-side outlet. The calculation formula is: in, is the water vapor flow rate at the wet side outlet of the humidifier, is the saturated vapor pressure at the wet side outlet of the humidifier, P hu,humid,out is the wet side outlet pressure of the humidifier, T hu,humid,out is the wet side outlet temperature of the humidifier; S45: Calculate the working fluid at the inlet and outlet of the humidifier Value; the mixed working medium of the humidifier inlet and outlet Value for logistics The calculation and logistics The calculation method of the mixed working fluid at the inlet and outlet of the intercooler The calculation method of the value is the same, but it is necessary to consider the calculation difference of water in different existence states in the mixed working fluid. The calculation formula is: Ex hu =m hu ·ex hu The logistics of the mixed working medium at the inlet and outlet of the humidifier are calculated Including calculation of enthalpy, entropy and flow of mixed working fluid at the inlet and outlet of humidifier Calculation: The enthalpy and entropy of the mixed working fluid at the inlet and outlet of the humidifier are the average values ​​of the enthalpy and entropy of the gaseous working fluid and the liquid working fluid, and the calculation formula is: H hu =(H hu,gas ×N hu,gas +H hu,liquid ×N hu,liquid ) / N hu S hu =(S hu,gas ×N hu,gas +S hu,liquid ×N hu,liquid ) / N hu The enthalpy and entropy of the gaseous working medium are obtained by looking up the table according to the working medium composition and working medium state, and are expressed as: H hu,gas =refpropm(′H′,′T′,T hu ,′P′,P hu ,′oxygen′,′nitrogen′,′water′,x hu,gas ) S hu,gas =refpropm(′S′,′T′,T hu ,′P′,P hu ,′oxygen′,′nitrogen′,′water′,x hu,gas ) The liquid working medium is liquid water, and its enthalpy and entropy values ​​are obtained by looking up the table and expressed as: H hu,liquid =refpropm(′H′,′T′,T hu ,′Q′,0,′water′) S hu,liquid =refpropm(′S′,′T′,T hu ,′Q′,0,′water′) The logistics ratio of the mixed working medium at the inlet and outlet of the humidifier For physical ratio Chemical ratio The sum is calculated as follows:

9. The method according to claim 1 A fuel cell air system evaluation method, characterized in that: Step S5 specifically includes the following steps: S51: Calculate air filter Loss and Efficiency of the air filter The loss is the mixed working fluid at the air filter inlet Value and outlet mixed working fluid The difference between the values ​​is calculated as: Ex D,af =Ex af,in -Ex af,out Among them, Ex D,af For air filter Loss, Ex af,in and Ex af,out The mixed working fluid at the inlet and outlet of the air filter value; The air filter Efficiency as product and fuel The ratio of the mixed working fluid at the air filter outlet and inlet The ratio of the values ​​is calculated as: Among them, η ex,af For air filter Efficiency, Ex P,i The product of the jth component Ex F,i is the fuel of the jth component S52: Calculate the air compressor Loss and efficiency of the air compressor; The loss is the mixed working fluid at the inlet of the air compressor The sum of the value and the parasitic power consumed by the air compressor and the mixed working medium at the outlet of the air compressor The difference between the values ​​is calculated as: Ex D,ac =Ex ac,in -Ex ac,out +W ac The air compressor Efficiency as product and fuel The ratio of the mixed working fluid at the outlet and inlet of the air compressor The ratio of the value to the sum of the parasitic power consumed by the air compressor is calculated as: S53: Calculation of intercooler Loss and efficiency of the intercooler; The loss is the mixed working fluid at the intercooler inlet Value and outlet mixed working fluid The difference between the values ​​is calculated as: Ex D,ic =Ex ic,in -Ex ic,out The intercooler Efficiency as product and fuel The ratio of the intercooler outlet and inlet mixed working fluid The ratio of the values ​​is calculated as: S54: Computational humidifier Loss and Efficiency of the humidifier The loss is the mixed working fluid at the humidifier inlet Value and outlet mixed working fluid The difference between the values, where the inlet and outlet include the four inlets and outlets on the dry side and wet side of the humidifier respectively, is calculated as follows: Ex D,hu =Ex hu,dry,in +Ex hu,humid,in -Ex hu,dry,out -Ex hu,humid,out The humidifier Efficiency as product and fuel The ratio of the mixed working fluid at the humidifier outlet and inlet The ratio of the values ​​is calculated as: S55: Calculation of fuel cell air system Loss and efficiency of the fuel cell air system; Losses for various components of the air system The sum of the losses is calculated as: Ex D,system,ari =∑Ex D,j =Ex D,af +Ex D,ac +Ex D,ic +Ex D,hu The fuel cell air system Efficiency as product and fuel The ratio of the mixed working medium at the outlet of the air system Value and inlet mixed medium The ratio of the value to the sum of the system parasitic power consumption is calculated as:

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