A calculation method for dynamic thermal management model of fuel cell and lithium battery hybrid power system

Abstract

The present invention provides a calculation method for a dynamic thermal management model of a fuel cell and lithium battery hybrid power system, including: S1, mathematically deconstructing and reconstructing the heat transfer of the fuel cell and lithium battery hybrid power system with reduced dimension, and constructing a one-dimensional dynamic model of heat transfer of the fuel cell, lithium battery and system ancillary equipment on the basis of reduced dimension reconstruction; S2, assembling the model to establish a heat source model of the system; according to the assembly result, the system energy conservation equation is obtained based on energy conservation, mass conservation, conduction and heat convection models; S3, constructing model constraints, and finally calculating heat transfer and conversion characteristics under different system power supply modes, analyzing the system at each key deconstruction node and their interactions, and obtaining the system heat transfer dynamic response, the characterization of the system thermal management performance and the change law of each temperature node of the system. The present invention provides a more accurate thermal management basis for the hybrid power system, which helps to optimize the thermal management strategy.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal management of fuel cells and lithium batteries, and in particular to a method for calculating a dynamic thermal management model of a hybrid power system of a fuel cell and a lithium battery. Background Art

[0002] With the intensification of the global energy crisis and environmental pollution, the development of hybrid power systems of fuel cells and lithium batteries is particularly critical. This hybrid power system provides efficient and environmentally friendly energy solutions for various transportation fields with the high energy conversion efficiency of fuel cells and the high energy density of lithium batteries. However, in the working process of fuel cells and lithium batteries, the problem of heat management has become increasingly prominent. A large amount of heat will be released during the operation of the power system. If the heat cannot be effectively managed, the system temperature will rise, which will affect the performance and life of the power, and may even cause serious safety problems such as fire. In response to this problem, there are mainly the following solutions in the prior art: 1) Passive heat dissipation system, which dissipates heat through air convection between battery packs or by adding heat sinks. However, this method has limited heat dissipation effect and cannot meet the heat dissipation requirements of high-performance battery packs under high load conditions. 2) Active heat dissipation system, including air cooling and water cooling systems. Although it can take away the heat generated by the battery pack more quickly, it increases the complexity and maintenance cost of the system, and also requires additional energy to drive the heat dissipation system. 3) Thermal management technology, by monitoring the temperature of the battery pack and controlling the opening and closing of the heat dissipation system based on a preset temperature threshold. However, this method lacks precise control over the real-time temperature distribution of the battery pack and cannot effectively deal with the situation where the temperature difference between different areas in the battery pack is large. 4) Thermal management model. Some technologies have proposed thermal management methods based on thermal management models, but these models are often oversimplified and cannot accurately reflect the complex heat conduction and convection processes inside the battery pack, resulting in poor thermal management effects.

[0003] Based on the defects of the above-mentioned prior art, the present invention proposes a method for calculating a dynamic thermal management model of a fuel cell and lithium battery hybrid power system. The method establishes an accurate thermal management model by calculating the temperature distribution of the fuel cell and the lithium battery in real time, and combining the structural parameters and working state of the power system. The model can accurately predict the temperature change trend of each internal area, and dynamically adjust the operating state of the heat dissipation system according to the prediction results to achieve efficient and safe heat dissipation of the power system. Through the technical solution of the present invention, not only can the problems of the prior art in heat management be effectively solved, but also the working efficiency and safety of the power system can be further improved, meeting the needs for an efficient energy management system.

[0004] The dynamic thermal management model is designed for the characteristics of the fuel cell and lithium battery hybrid system, aiming to monitor and adjust the system temperature in real time to ensure that it operates in the best working state. This model needs to dynamically adjust the heat dissipation strategy according to the real-time working conditions of the system and external environmental conditions to maintain the stability of the system temperature. With the continuous development of computer technology and sensor technology, the dynamic thermal management model has been realized and continuously optimized. Through precise sensors and advanced control algorithms, key parameters such as temperature, current, and voltage of the system can be monitored in real time, and the working state of the heat dissipation system can be dynamically adjusted according to these parameters to achieve the best thermal management effect.

[0005] In summary, the background technology of the calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid system is mainly based on the development of new energy technology, the demand and development of the dynamic thermal management model, and the progress and application of the calculation method. The development of these technologies has provided strong support for the realization and optimization of the dynamic thermal management model, and also brought more reliable energy management solutions to the application of related fields. Looking to the future, with the continuous advancement and innovation of related technologies, the dynamic thermal management of the fuel cell and lithium battery hybrid system will be more intelligent and efficient, injecting new vitality into the development of new energy vehicles and other fields.

[0006] The existing technology can be summarized into the following aspects:

[0007] 1. Hybrid power system modeling technology: For fuel cell and lithium battery hybrid power systems, modeling is the basis for understanding and optimizing system performance. In the existing technology, modeling usually takes into account the characteristics of fuel cells, lithium batteries, and internal combustion engines (if included in the system). For example, the output characteristics of fuel cells, the charging and discharging characteristics of lithium batteries, and the fuel consumption rate and emission characteristics of internal combustion engines are all factors that need to be considered when modeling. These models not only help to understand the operating principles of the system, but also provide a basis for subsequent energy management and thermal management.

[0008] 2. Energy management algorithm: In hybrid power systems, energy management algorithm is the key. At present, commonly used energy management algorithms include rule-based and optimization-based. Rule-based algorithms are simple and easy to understand, but may not achieve optimal performance. Optimization-based algorithms, such as dynamic programming and genetic algorithms, can maximize the utilization of fuel cells and the energy efficiency of the system while meeting the system performance requirements.

[0009] 3. Dynamic thermal management technology: For the dynamic thermal management of fuel cell and lithium battery hybrid systems, existing technologies mainly focus on how to monitor and control system temperature in real time to prevent overheating or overcooling from affecting battery performance. This includes using advanced sensor technology to monitor battery temperature in real time, and using effective heat dissipation systems such as fans and heat sinks to ensure that the battery operates within an appropriate temperature range.

[0010] 4. Computational methods and simulation technology: In terms of computational methods and simulation technology, existing technologies have been able to use advanced mathematical models and simulation software to simulate the actual operation of hybrid power systems. For example, MATLAB / Simulink and other software can be used to model and simulate the system to evaluate the performance of different energy management and thermal management strategies. In addition, there are some specialized simulation tools, such as AMESim, which can be used to simulate and analyze the thermal characteristics of hybrid power systems in more detail.

[0011] 5. Practical application and optimization: In practical applications, the calculation method of the dynamic thermal management model needs to be optimized according to the specific vehicle model and operating environment. For example, in electric vehicles, it may be necessary to consider passenger comfort and battery safety; in the aerospace field, it may be necessary to focus more on system stability and lightweight. Therefore, the existing technology also includes customized optimization methods for different application scenarios.

[0012] In summary, the existing technologies for the calculation method of the dynamic thermal management model of fuel cell and lithium battery hybrid power system have covered modeling, energy management, dynamic thermal management, calculation method and simulation, as well as practical application and optimization. The development of these technologies has provided strong support for the performance improvement and wide application of hybrid power system. Summary of the invention

[0013] In response to the technical problems raised above, a calculation method for a dynamic thermal management model of a fuel cell and lithium battery hybrid power system is provided.

[0014] The technical means adopted by the present invention are as follows:

[0015] A method for calculating a dynamic thermal management model of a fuel cell and lithium battery hybrid power system comprises the following steps:

[0016] S1. Perform mathematical deconstruction and dimensionality reduction reconstruction of heat transfer of fuel cell and lithium battery hybrid system, and build a one-dimensional dynamic model of heat transfer of fuel cell, lithium battery and system accessories based on dimensionality reduction reconstruction;

[0017] S2. Assemble the model and establish the heat source model of the system; according to the assembly results, obtain the system energy conservation equation based on the law of conservation of energy, the law of conservation of mass, conduction and heat convection models;

[0018] S3. Construct model constraints, and finally calculate the heat transfer and conversion characteristics under different system power supply modes, analyze the system at each key deconstruction node and their interactions, obtain the system heat transfer dynamic response, the system thermal management performance characterization and the change law of each temperature node of the system.

[0019] Furthermore, in step S1, the one-dimensional dynamic model of heat transfer is a one-dimensional thermal resistance model under heat transfer, which satisfies the following formula:

[0020]

[0021] Wherein, the subscripts h and c represent the hot fluid and the cold fluid, G c is the heat capacity of the cold fluid, G h is the heat capacity of the hot fluid, and KA is the thermal conductivity of the heat exchange.

[0022] Further, the heat transfer thermal resistance of the fuel cell and lithium battery hybrid system includes gas thermal resistance, convection thermal resistance, thermal conduction thermal resistance, fuel cell cooling thermal resistance, lithium battery cooling thermal resistance, sensible heat humidity thermal resistance and latent heat humidity thermal resistance;

[0023] The gas thermal resistance satisfies the following formula:

[0024]

[0025] Among them, R gas is the thermal resistance of any gas, G gas is the heat capacity of the gas, (KA) gas is the thermal conductivity of gas heat exchange;

[0026] The convection thermal resistance satisfies the following formula:

[0027]

[0028] Among them, R hcv is any convection thermal resistance, h is the corresponding convection heat transfer coefficient, A i is any convective heat transfer area;

[0029] The thermal resistance satisfies the following formula:

[0030]

[0031] Among them, R hcd is any thermal resistance, δ i is the corresponding thermal conductive surface thickness, A i is any heat conduction area, λ h,i is the thermal conductivity;

[0032] The fuel cell cooling thermal resistance satisfies the following formula:

[0033]

[0034] Among them, R cool,fc is the cooling thermal resistance of the fuel cell, G bp is the heat capacity of the bipolar plate, G cw is the heat capacity of cooling seawater, (KA) cool Thermal conductivity for cooling heat exchange;

[0035] The lithium battery cooling thermal resistance satisfies the following formula:

[0036]

[0037] Among them, R cool,cw is the cooling thermal resistance of the lithium battery, G cw is the heat capacity of cooling seawater, (KA) cool Thermal conductivity for cooling heat exchange;

[0038] The sensible heat humidity thermal resistance satisfies the following formula:

[0039]

[0040] Among them, R h is the sensible heat and humidity thermal resistance, G c1 is the heat capacity of humidity 1, NTU e is the number of heat transfer units for the sensible heat of cooling;

[0041] The latent heat humidity thermal resistance satisfies the following formula:

[0042]

[0043] Among them, R m is the latent heat humidity thermal resistance, G c2 is the heat capacity of humidity 2, NTU m is the number of heat transfer units for the latent heat of cooling.

[0044] Furthermore, in step S2, the heat source model includes heat generated by the fuel cell, heat dissipated by the fuel cell, heat generated by the lithium battery, heat dissipated by the lithium battery, net heat of the gas, anode gas heat, cathode gas heat, convection heat, conduction heat, cooling heat of the fuel cell, cooling heat of the lithium battery, ohmic heat and activation heat.

[0045] Furthermore, the heat generated by the fuel cell satisfies the following formula:

[0046]

[0047] in, is the average heat transfer rate of the fuel cell, is the molar flow rate of hydrogen consumption, is the higher calorific value of hydrogen, is the average power of the fuel cell;

[0048] The heat dissipation of the fuel cell satisfies the following formula:

[0049]

[0050] in, is the average heat generated by the fuel cell, The gas heat of hydrogen, To cool down the heat, is convection heat;

[0051] The heat generated by the lithium battery satisfies the following formula:

[0052]

[0053] in, is the average heat transfer rate of lithium battery, η B is the charging and discharging efficiency of lithium battery, sgn(P B ) is the symbol function, is the power of lithium battery;

[0054] The heat dissipation of the lithium battery satisfies the following formula:

[0055]

[0056] in, is the heat dissipation of the lithium battery, Cooling heat from lithium batteries;

[0057] The net heat of the gas satisfies the following formula:

[0058]

[0059] in, is the net heat of the gas, is the heat of gas outlet, is the heat of gas inlet;

[0060] The anode gas heat satisfies the following formula:

[0061] Q gas,an =(T cha,an -T gas,in,an ) / R gas,an ;

[0062] Among them, Q gas,an is the anode gas heat, T cha,anis the anode channel layer temperature, T gas,in,an is the temperature of the anode gas entering the gas,an is the thermal resistance of the anode;

[0063] The cathode gas heat satisfies the following formula:

[0064] Q gas,ca =(T gas,in,ca -T cha,ca ) / R gas,ca ;

[0065] Among them, Q gas,ca is the cathode gas heat, T gas,in,ca is the cathode channel layer temperature, T cha,ca is the temperature of the cathode gas entering, R gas,ca is the thermal resistance of the cathode;

[0066] The convective heat satisfies the following formula:

[0067] Q hcv,i =(T i+1 -T i ) / R hcv,i ;

[0068] Among them, Q hcv,i is the convective heat of single cell i, T i+1 is the overall temperature of the single cell i+1, T i is the overall temperature of single cell i, R hcv,i is the overall convection thermal resistance of single cell i;

[0069] The conduction heat satisfies the following formula:

[0070] Q hcd,i =(T i+1 -T i ) / R hcd,i ;

[0071] Among them, Q hcd,i is the conduction heat of single cell i, T i+1 is the overall temperature of the single cell i+1, T i is the overall temperature of single cell i, R hcd,i is the overall conduction thermal resistance of single cell i;

[0072] The cooling heat of the fuel cell satisfies the following formula:

[0073] Q cool,bp =(T bp -T cw ) / R cool,bp ;

[0074] Among them, Q cool,bpis the cooling heat of the bipolar plate, T bp is the temperature of the bipolar plate, T cw is the cooling temperature of the single cell, R cool,bp is the cooling thermal resistance of the bipolar plate;

[0075] The cooling heat of the lithium battery satisfies the following formula:

[0076] Q cool,sw =(T cw,out -T sw,in ) / R cool,sw ;

[0077] Among them, Q cool,sw is the cooling heat of the lithium battery, T cw,out is the fuel cell cooling outlet temperature, T sw,in The inlet temperature of the lithium battery cooling, R cool,sw is the cooling thermal resistance of the lithium battery;

[0078] The ohmic heat satisfies the following formula:

[0079]

[0080] in, is the ohmic heat of single cell i, is the square of the fuel cell current, A i is the cross-sectional area of ​​single cell i, ASR i is the area specific resistance of single cell i;

[0081] The activation heat satisfies the following formula:

[0082]

[0083] in, is the activation heat of the fuel cell, I FC is the current of the fuel cell, V act is the activation voltage.

[0084] Furthermore, in step S2, the system energy conservation equation includes the energy conservation of the fuel cell proton membrane, the energy conservation of the fuel cell anode catalyst layer, the energy conservation of the fuel cell cathode catalyst layer, the energy conservation of the fuel cell microporous layer, the energy conservation of the fuel cell gas diffusion layer, the energy conservation of the fuel cell channel layer and the energy conservation of the fuel cell bipolar plate.

[0085] Furthermore, the fuel cell proton membrane energy conservation satisfies the following formula:

[0086]

[0087] Where C is the equivalent specific heat capacity of the membrane, M is the mass of the membrane, T mis the temperature of the film, t is the time term, is the ohmic heat of the membrane, is the heat conduction between the cathode catalyst layer and the membrane, is the heat conduction of the film, is the convective heat of the membrane;

[0088] The energy conservation of the anode catalyst layer of the fuel cell satisfies the following formula:

[0089]

[0090] Where C is the equivalent specific heat capacity of the anode catalyst layer, M is the mass of the anode catalyst layer, T acl is the temperature of the anode catalyst layer, t is the time term, is the ohmic heat of the anode catalyst layer, is the heat conduction of the film, is the heat conduction of the anode catalyst layer, is the convection heat of the anode catalyst layer;

[0091] The energy conservation of the cathode catalyst layer of the fuel cell satisfies the following formula:

[0092]

[0093] Where C is the equivalent specific heat capacity of the cathode catalyst layer, M is the mass of the cathode catalyst layer, T ccl is the temperature of the cathode catalyst layer, t is the time term, is the ohmic heat of the cathode catalyst layer, is the activation heat of the cathode catalyst layer, is the heat conduction between the cathode catalyst layer and the membrane, It is the heat conduction between the cathode catalyst layer and the cathode side microporous layer. is the convective heat of the cathode catalyst layer;

[0094] The energy conservation of the microporous layer of the fuel cell satisfies the following formula:

[0095]

[0096] Where C is the equivalent specific heat capacity of the microporous layer, M is the mass of the microporous layer, and T mpl is the temperature of the microporous layer, t is the time term, is the ohmic heat of the microporous layer, is the heat conduction of the catalyst layer, is the heat conduction of the microporous layer, is the convective heat of the microporous layer;

[0097] The energy conservation of the fuel cell gas diffusion layer satisfies the following formula:

[0098]

[0099] Where C is the equivalent specific heat capacity of the gas diffusion layer, M is the mass of the gas diffusion layer, T gdl is the temperature of the gas diffusion layer, t is the time term, is the ohmic heat of the gas diffusion layer, is the heat conduction of the microporous layer, is the heat conduction of the gas diffusion layer, is the convective heat of the gas diffusion layer;

[0100] The energy conservation of the fuel cell channel layer satisfies the following formula:

[0101]

[0102] Where C is the equivalent specific heat capacity of the channel layer, M is the mass of the channel layer, T cha is the temperature of the channel layer, t is the time term, To remove heat from the gas, For the gas to enter the heat, is the convective heat of the channel layer;

[0103] The energy conservation of the fuel cell bipolar plate satisfies the following formula:

[0104]

[0105] Where C is the equivalent specific heat capacity of the bipolar plate, M is the mass of the bipolar plate, T bp is the temperature of the bipolar plate, t is the time term, is the ohmic heat of the bipolar plate, is the heat conduction of the gas diffusion layer, To cool the bipolar plates, is the convective heat of the bipolar plates.

[0106] Furthermore, in step S3, an equivalent network of thermal resistance and capacitance of the fuel cell and lithium battery hybrid system is constructed based on the heat flow method and Kirchhoff's law, a dynamic model of heat transfer of the fuel cell and lithium battery hybrid system is completed, a matrix expression of the constraints of the model is listed, and heat transfer and conversion characteristics are calculated; the model includes conduction and convection heat transfer modes, so as to predict and analyze the dynamic response of the thermal interface at different time and space scales.

[0107] Furthermore, the thermal resistance and capacitance of the anode channel layer of the fuel cell satisfy the following formula:

[0108] T gas,an,j +Q gas,an,j R gas,an,j =T cha,an ;

[0109] Among them, T gas,an,j is the temperature of the anode gas in the jth channel, Q gas,an,j is the heat of the anode gas in the jth channel, R gas,an,j is the thermal resistance of the anode gas in the jth channel, T cha,an is the overall temperature of the anode bipolar plate;

[0110] The thermal resistance and capacitance of the cathode layer of the fuel cell satisfy the following formula:

[0111] T gas,ca,j -Q gas,ca,j R gas,ca,j =T cha,ca ;

[0112] Among them, T gas,ca,j is the temperature of the cathode gas in the jth channel, Q gas,ca,j is the heat of cathode gas in the jth channel, R gas,ca,j is the thermal resistance of the cathode gas in the jth channel, T cha,ca is the overall temperature of the cathode bipolar plate;

[0113] The fuel cell anode cooling thermodynamic equation satisfies the following formula:

[0114] T cw,in +ε cw,an -Q cool,sw R cool,sw =T sw,in ;

[0115] Among them, T cw,in is the temperature of the fuel cell cooling water entering the fuel cell, ε cw,an is the thermodynamic potential of the fuel cell anode, Q cool,sw For cooling heat, R cool,sw is the cooling thermal resistance, T sw,in The temperature of the cooling water entering the lithium battery;

[0116] The fuel cell cathode cooling thermodynamic equation satisfies the following formula:

[0117] T cw,in +ε cw,ca -Q cool,sw R cool,sw =T sw,in ;

[0118] Among them, T cw,in is the temperature of the fuel cell cooling water entering the fuel cell, ε cw,ca is the thermodynamic potential of the fuel cell cathode, Q cool,sw For cooling heat, R cool,sw is the cooling thermal resistance, T sw,in The temperature of the cooling water entering the lithium battery;

[0119] The thermal resistance and capacitance between the fuel cell anode and the environment satisfy the following formula:

[0120] T env +Q hcv,cha R hcv,cha +Q gas,an,in R gas,an,in =T gas,an,in ;

[0121] Among them, T env is the ambient temperature, Q hcv,cha is the convective heat transfer of the fuel cell bipolar plate, R hcv,cha is the convective heat transfer resistance of the fuel cell bipolar plate, Q gas,an,in is the heat of the anode gas entering, R gas,an,in is the thermal resistance of anode gas entering, T gas,an,in is the temperature of the anode gas entering;

[0122] The thermal resistance and capacitance between the fuel cell cathode and the environment satisfy the following formula:

[0123] T env +Q hcv,cha R hcv,cha +Q gas,ca,in R gas,ca,in =T gas,ca,in ;

[0124] Among them, T env is the ambient temperature, Q hcv,cha is the convective heat transfer of the fuel cell bipolar plate, R hcv,cha is the convective heat transfer resistance of the fuel cell bipolar plate, Q gas,ca,in is the heat of cathode gas entering, R gas,ca,in is the thermal resistance of cathode gas entering, T gas,ca,in is the temperature of cathode gas entering;

[0125] The thermal resistance and capacitance of the anode bipolar plate of the i-th single cell in the fuel cell and the lithium battery satisfy the following formula:

[0126] T env +Q hcv,i R hcv,i -∑Q hcd,i R hcd,i -Q cool,abp R cool,abp +ε cw,i -Q cool,sw R cool,sw =T sw,in ;

[0127] Among them, T env is the ambient temperature, Q hcv,iis the convective heat transfer of the i-th single battery, R hcv,i is the convection heat transfer resistance of the ith single cell, ∑Q hcd,i R hcd,i Q is the product of the heat conduction and thermal resistance of all i cells. cool,abp is the cooling heat of the anode bipolar plate, R cool,abp is the thermal resistance of the anode bipolar plate, ε cw,i is the cooling thermal potential of the ith battery, Q cool,sw Cooling heat for lithium batteries, R cool,sw is the thermal resistance of lithium battery cooling, T sw,in is the temperature of cooling water entering;

[0128] The thermal resistance and capacitance of the cathode bipolar plate and the lithium battery of the i-th single cell in the fuel cell satisfy the following formula:

[0129] T env +Q hcv,i R hcv,i -∑Q hcd,i R hcd,i -Q cool,cbp R cool,cbp +ε cw,i -Q cool,sw R cool,sw =T sw,in ;

[0130] Among them, T env is the ambient temperature, Q hcv,i is the convective heat transfer of the i-th single battery, R hcv,i is the convection heat transfer resistance of the ith single cell, ∑Q hcd,i R hcd,i Q is the product of the heat conduction and thermal resistance of all i cells. cool,cbp is the cooling heat of the cathode bipolar plate, R cool,cbp is the thermal resistance of the cathode bipolar plate, ε cw,i is the cooling thermal potential of the ith battery, Q cool,sw Cooling heat for lithium batteries, R cool,sw is the thermal resistance of lithium battery cooling, T sw,in is the cooling water inlet temperature.

[0131] Furthermore, in step S3, different modes of the hybrid power system include: a pure fuel cell power supply mode, a fuel cell and lithium battery combined power supply mode, and a lithium battery charging power compensation mode.

[0132] Compared with the prior art, the present invention has the following advantages:

[0133] 1. The present invention can improve system efficiency and stability: The calculation method of the model can ensure that the system can maintain efficient and stable operation under different working conditions by accurately controlling and managing the heat generated by the fuel cell and lithium battery during operation. By evenly distributing and efficiently transferring heat, the system performance degradation or failure caused by overheating or overcooling can be reduced, thereby improving the overall efficiency and reliability of the system.

[0134] 2. The present invention can optimize the energy management strategy: The present invention provides a more accurate thermal management basis for the hybrid power system, helps to optimize the thermal management strategy, can prevent the thermal runaway of the fuel cell and lithium battery to the greatest extent, make up for their shortcomings, and improve the energy utilization and economy of the entire system.

[0135] 3. The present invention can extend the life of the system: effective thermal management can reduce the thermal stress of the internal components of the system, reduce material aging and performance degradation caused by high temperature, and thus extend the service life of the system. Especially under extreme environmental conditions, such as high or low temperature environments, the calculation method of the dynamic thermal management model can ensure the stable operation of the system and avoid damage to the system due to overheating or overcooling.

[0136] In summary, the present invention has significant beneficial effects in improving system efficiency and stability, optimizing thermal management strategies, extending system life, promoting the development of new energy industries, and protecting the environment and saving energy.

[0137] Based on the above reasons, the present invention can be widely promoted in the fields of electric vehicle industry, new energy powered ship field, aerospace field, power supply for large equipment, renewable energy grid connection, military and emergency power supply, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0138] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0139] Figure 1 The present invention is a flowchart of a method for calculating a dynamic thermal management model of a fuel cell and lithium battery hybrid power system.

[0140] Figure 2 This is a diagram showing the thermal resistance of the hybrid power system of the fuel cell and lithium battery of the present invention.

[0141] Figure 3 This is a heat balance diagram of a fuel cell single cell and a fuel cell stack of the present invention.

[0142] Figure 4The thermal resistance and heat capacity network diagram of the fuel cell single cell and hybrid power system of the present invention, wherein (a) is the one-dimensional thermal resistance diagram of the single cell, and (b) is the thermal resistance and heat capacity network diagram of the fuel cell and lithium battery system.

[0143] Figure 5 Calculate the matrix diagram for the present invention.

[0144] Figure 6 This is a diagram showing the thermal response results of the pure PEMFC power supply mode of the system of the present invention.

[0145] Figure 7 This is a diagram showing the thermal response results of the PEMFC and LIB combined power supply operation mode of the system of the present invention.

[0146] Figure 8 This is an analysis diagram of the thermal response results of the LIB power compensation mode of the system of the present invention. DETAILED DESCRIPTION

[0147] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0148] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0149] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0150] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0151] The present invention provides a calculation method for the thermal management model of a fuel cell and lithium battery hybrid power system, and performs mathematical deconstruction and dimensionality reduction reconstruction of heat transfer for typical power equipment of the system. Based on the dimensionality reduction reconstruction, a one-dimensional plus (1D+) dynamic model of heat transfer of fuel cells, lithium batteries and related auxiliary equipment is constructed. After the model is assembled, the model constraints are constructed. Finally, the heat transfer and conversion characteristics are calculated under different system power supply modes, and the system is accurately analyzed at each key deconstruction node and their interactions to obtain the system heat transfer dynamic response, the characterization of the system thermal management performance and the change law of each temperature node of the system.

[0152] In the first step, the heat transfer of the fuel cell and lithium battery hybrid system is mathematically deconstructed, and the key components of the system, such as fuel cells, lithium batteries and system accessories, are expressed as a one-dimensional mathematical expression of thermal resistance under heat transfer.

[0153] In the second step, for the typical fuel cell and lithium battery hybrid system process, based on the thermal resistance established in the first step, one-dimensional assembly is carried out and expressions for various heat sources of the system are established.

[0154] The third step is to derive the system energy conservation equation based on the energy law, mass conservation law, conduction and heat convection equations according to the assembly results of the system in the second step.

[0155] The fourth step is to construct an equivalent network of thermal resistance and capacitance of the fuel cell and lithium battery hybrid system based on the heat flow method and Kirchhoff's law, complete the dynamic model of heat transfer, list the matrix expression of the constraints of the model, and calculate the heat transfer and conversion characteristics.

[0156] The different modes of the hybrid power system of the present invention are: a pure fuel cell power supply mode, a fuel cell and lithium battery combined power supply mode, and a lithium battery charging power compensation mode.

[0157] In the fifth step, the calculation results can obtain the dynamic response of the hybrid system heat transfer, the characterization of the system thermal management performance and the change law of each temperature node of the system.

[0158] The application fields of the present invention mainly include the following aspects:

[0159] 1) Electric vehicle industry: This is the most direct and widespread application area of ​​the dynamic thermal management model of fuel cell and lithium battery hybrid systems. With the rapid development of the electric vehicle market, how to improve the efficiency and safety of the battery system has become a key issue. The dynamic thermal management model can help achieve effective thermal control of the battery system, thereby improving the battery life and performance, while also ensuring the safety of electric vehicles.

[0160] 2) New energy powered ship field: By precisely controlling the temperature of the power system, it can be ensured that it works in the best condition, thereby improving energy efficiency. Effective thermal management can reduce the thermal decay of key components such as batteries and fuel cells, and extend their service life. It prevents safety accidents such as fire or explosion caused by overheating of the power system, and ensures the safety of ship operation.

[0161] 3) Aerospace: In the aerospace field, the stability and efficiency of the power system are crucial. Fuel cell and lithium battery hybrid power systems combined with dynamic thermal management models can provide more efficient and stable energy supply, thus meeting the stringent requirements of aerospace for power systems.

[0162] 4) Power supply for large equipment: For some large equipment that needs to run continuously for a long time, such as data centers, communication base stations, etc., stable power supply is the key to ensure the normal operation of the equipment. Fuel cell and lithium battery hybrid system combined with dynamic thermal management can provide continuous and stable power output and ensure the stable operation of the system in high or low temperature environments.

[0163] 5) Renewable energy grid connection: In the field of renewable energy grid connection, due to the instability of renewable energy such as wind and solar energy, a stable energy storage system is needed to balance the fluctuations of the power grid. Fuel cell and lithium battery hybrid system can be used as an effective energy storage solution, combined with dynamic thermal management technology, it can improve the efficiency and stability of the energy storage system.

[0164] 6) Military and emergency power supply: In the military and emergency fields, the reliability and durability of the power supply system are crucial. Fuel cell and lithium battery hybrid power systems have the advantages of high efficiency, environmental protection, and low noise. Combined with dynamic thermal management technology, they can ensure stable and reliable power supply in various harsh environments.

[0165] In summary, the calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system has broad application prospects in many fields and is of great significance to improving energy utilization efficiency, enhancing system stability and extending equipment service life.

[0166] Example 1

[0167] 1. A method for calculating a thermal management model of a fuel cell and lithium battery hybrid power system of the present invention comprises the following steps:

[0168] The heat transfer mathematical deconstruction and dimensionality reduction reconstruction of typical power equipment in the fuel cell and lithium battery hybrid system are carried out. Based on the dimensionality reduction reconstruction, a one-dimensional dynamic model of heat transfer of fuel cells, lithium batteries and related auxiliary equipment is constructed. After the model is assembled, the model constraints are constructed. Finally, the heat transfer and conversion characteristics are calculated under different system power supply modes, and the system is accurately analyzed at each key deconstruction node and their interactions to obtain the system heat transfer dynamic response, the system thermal management performance characterization and the change law of each temperature node of the system.

[0169] 2. The first step is Figure 2 As shown, the heat transfer mathematical deconstruction of the fuel cell and lithium battery hybrid system is carried out, and the key components of the system, such as the fuel cell, lithium battery and system accessories, are expressed as a one-dimensional thermal resistance mathematical expression under heat transfer. In this embodiment, Figure 2 The fuel cell and lithium battery hybrid power system in the invention can be an existing system, which includes a fuel cell stack, an air compressor, a heat exchanger, a gas-liquid separator, a humidifier 1, a humidifier 2, a hydrogen bottle, a regenerator, a hydrogen circulation compressor, a boost converter, an inverter, a frequency converter, a lithium battery, an electric motor, a propeller, etc. The air compressor is connected to the heat exchanger through a pipeline 1, the heat exchanger is connected to the humidifier 1 through a pipeline 2, and the humidifier 1 is connected to the fuel cell stack through a pipeline 3. The fuel cell stack is connected to the gas-liquid separator through a pipeline 4, the gas-liquid separator is connected to the humidifier 1 through a pipeline 7, the humidifier 1 is connected to the humidifier 2, and the humidifier 2 is connected to the fuel cell stack through a pipeline 13. The humidifier 2 is also connected to a pipeline 8. The hydrogen bottle is connected to the valve through pipeline 9, the regenerator is connected to the humidifier 2 through pipeline 12, the gas-liquid separator is connected to the regenerator through pipeline 5, and pipelines 6, 11, and 16 are also connected to the regenerator. Pipeline 11 is connected to the valve through pipeline 10, and pipeline 16 is connected between pipeline 10 and pipeline 11. The fuel cell stack is connected to the hydrogen circulation compressor through pipeline 14, and the hydrogen circulation compressor is connected to the regenerator through pipeline 15. The fuel cell stack is connected to the boost converter, the boost converter is connected to the inverter, the lithium battery is connected to the frequency converter, the frequency converter is connected to the inverter, the inverter is connected to the motor, and the motor is connected to the propeller.

[0170] The general one-dimensional thermal resistance form is as follows:

[0171]

[0172] Wherein, the subscripts h and c represent the hot fluid and the cold fluid, G c represents the heat capacity of the cold fluid, G h represents the heat capacity of the hot fluid and KA represents the thermal conductivity of the heat exchanger. This equation explains the complex heat transfer mechanism in the heat exchanger through the arrangement of thermal resistances.

[0173] List the heat transfer resistances required for fuel cell and lithium battery hybrid systems.

[0174] 1) Gas thermal resistance

[0175]

[0176] Among them, R gas is the thermal resistance of any gas, G gas is the heat capacity of the gas, (KA) gas It represents the thermal conductivity of gas heat exchange.

[0177] 2) Convection thermal resistance

[0178]

[0179] Among them, R hcv is any convection thermal resistance, h is the corresponding convection heat transfer coefficient, A i represents any convective heat transfer area.

[0180] 3) Thermal resistance

[0181]

[0182] Among them, R hcd is any thermal resistance, δ i is the corresponding thermal conductive surface thickness, A i represents any thermal conductivity area, λ h,i Represents thermal conductivity.

[0183] 4) Fuel cell cooling thermal resistance

[0184]

[0185] Among them, R cool,fc is the cooling thermal resistance of the fuel cell, G bp Represents the heat capacity of the bipolar plate, G cw The heat capacity of cooling seawater, (KA) cool Represents the thermal conductivity of cooling heat exchange.

[0186] 5) Lithium battery cooling thermal resistance

[0187]

[0188] Among them, R cool,cw is the cooling thermal resistance of the lithium battery, G cw The heat capacity of cooling seawater, (KA) cool Represents the thermal conductivity of cooling heat exchange.

[0189] 6) Sensible heat and humidity thermal resistance

[0190]

[0191] Among them, R h is the sensible heat and humidity thermal resistance, G c1 Indicates the heat capacity of humidity 1, NTU e The number of heat transfer elements representing the sensible heat of cooling.

[0192] 7) Latent heat humidity thermal resistance

[0193]

[0194] Among them, R m is the latent heat humidity thermal resistance, G c2 Indicates the heat capacity of humidity 2, NTU m The number of heat transfer elements representing the latent heat of cooling.

[0195] 3. In the second step, for the typical fuel cell and lithium battery hybrid system process, based on the first step of deconstructing the thermal resistance of a single cell, a one-dimensional assembly is performed into a battery stack such as Figure 3 , and establish the heat expressions of various heat sources in the system.

[0196] Fuel cell power generation heat:

[0197]

[0198] in, is the average heat transfer rate of the fuel cell, is the molar flow rate of hydrogen consumption, Indicates the higher calorific value of hydrogen. is the average power of the fuel cell.

[0199] Heat dissipated by fuel cells:

[0200]

[0201] in, is the average heat generated by the fuel cell, The gas heat of hydrogen, Indicates cooling heat, It is convection heat.

[0202] Heat generated by lithium batteries:

[0203]

[0204] in, is the average heat transfer rate of lithium battery, η B is the charging and discharging efficiency of lithium battery, sgn(P B ) represents the symbolic function, is the power of lithium battery.

[0205] Heat dissipation of lithium battery:

[0206]

[0207] in, is the heat dissipation of the lithium battery, Cooling heat from lithium batteries.

[0208] Net heat of gas:

[0209]

[0210] in, is the net heat of the gas, is the heat of gas outlet, is the heat of gas inlet.

[0211] Anode gas heat:

[0212] Q gas,an =(T cha,an -T gas,in,an ) / R gas,an (14)

[0213] Among them, Q gas,an is the anode gas heat, T cha,an is the anode channel layer temperature, T gas,in,an is the temperature of the anode gas entering the gas,an is the thermal resistance of the anode.

[0214] Cathode gas heat:

[0215] Q gas,ca =(T gas,in,ca -T cha,ca ) / R gas,ca (15)

[0216] Among them, Q gas,ca is the cathode gas heat, T gas,in,ca is the cathode channel layer temperature, T cha,ca is the temperature of the cathode gas entering, R gas,ca is the thermal resistance of the cathode.

[0217] Convection Heat:

[0218] Q hcv,i =(T i+1 -T i ) / R hcv,i (16)

[0219] Among them, Q hcv,i is the convective heat of single cell i, T i+1 is the overall temperature of the single cell i+1, T i is the overall temperature of single cell i, R hcv,i is the overall convection thermal resistance of the single cell i.

[0220] Conduction heat:

[0221] Q hcd,i =(T i+1 -T i ) / R hcd,i (17)

[0222] Among them, Q hcd,i is the conduction heat of single cell i, T i+1 is the overall temperature of the single cell i+1, T i is the overall temperature of single cell i, R hcd,i is the overall thermal resistance of the single cell i.

[0223] Cooling heat (fuel cells):

[0224] Q cool,bp =(T bp -T cw ) / R cool,bp (18)

[0225] Among them, Q cool,bp is the cooling heat of the bipolar plate, T bp is the temperature of the bipolar plate, T cw is the cooling temperature of the single cell, R cool,bp is the cooling thermal resistance of the bipolar plate.

[0226] Cooling heat (lithium battery):

[0227] Q cool,sw =(T cw,out -T sw,in ) / R cool,sw (19)

[0228] Among them, Q cool,sw is the cooling heat of the lithium battery, T cw,out is the fuel cell cooling outlet temperature, T sw,in is the lithium battery cooling inlet temperature, R cool,swis the cooling thermal resistance of the lithium battery.

[0229] Ohm Heat:

[0230]

[0231] in, is the ohmic heat of single cell i, is the square of the fuel cell current, A i is the cross-sectional area of ​​single cell i, ASR i is the area specific resistance of single cell i.

[0232] Activation heat:

[0233]

[0234] in, is the activation heat of the fuel cell, I FC is the fuel cell current, V act is the activation voltage.

[0235] 4. The third step is to derive the system energy conservation equation based on the law of conservation of energy, law of conservation of mass, conduction and heat convection equations according to the system stack assembly results in the second step.

[0236] Energy conservation of fuel cell proton membrane:

[0237]

[0238] Where C is the equivalent specific heat capacity of the membrane, M is the mass of the membrane, T m is the temperature of the film, t is the time term, is the ohmic heat of the membrane, is the heat conduction between the cathode catalyst layer and the membrane, is the heat conduction of the film, is the convective heat of the membrane.

[0239] Energy conservation of fuel cell anode catalyst layer:

[0240]

[0241] Where C is the equivalent specific heat capacity of the anode catalyst layer, M is the mass of the anode catalyst layer, T acl is the temperature of the anode catalyst layer, t is the time term, is the ohmic heat of the anode catalyst layer, is the heat conduction of the film, is the heat conduction of the anode catalyst layer, is the convective heat of the anode catalyst layer.

[0242] Energy conservation in the cathode catalyst layer of a fuel cell:

[0243]

[0244] Where C is the equivalent specific heat capacity of the cathode catalyst layer, M is the mass of the cathode catalyst layer, T ccl is the temperature of the cathode catalyst layer, t is the time term, is the ohmic heat of the cathode catalyst layer, is the activation heat of the cathode catalyst layer, is the heat conduction between the cathode catalyst layer and the membrane, It is the heat conduction between the cathode catalyst layer and the cathode side microporous layer. is the convective heat of the cathode catalyst layer.

[0245] Energy conservation in the microporous layer of fuel cells:

[0246]

[0247] Where C is the equivalent specific heat capacity of the microporous layer, M is the mass of the microporous layer, and T mpl is the temperature of the microporous layer, t is the time term, is the ohmic heat of the microporous layer, is the heat conduction of the catalyst layer, is the heat conduction of the microporous layer, is the convective heat of the microporous layer.

[0248] Energy conservation of fuel cell gas diffusion layer:

[0249]

[0250] Where C is the equivalent specific heat capacity of the gas diffusion layer, M is the mass of the gas diffusion layer, T gdl is the temperature of the gas diffusion layer, t is the time term, is the ohmic heat of the gas diffusion layer, is the heat conduction of the microporous layer, is the heat conduction of the gas diffusion layer, is the convective heat of the gas diffusion layer.

[0251] Energy conservation in fuel cell channel layer:

[0252]

[0253] Where C is the equivalent specific heat capacity of the channel layer, M is the mass of the channel layer, T cha is the temperature of the channel layer, t is the time term, To remove heat from the gas, For the gas to enter the heat, is the convective heat of the channel layer.

[0254] Energy conservation of fuel cell bipolar plates:

[0255]

[0256] Where C is the equivalent specific heat capacity of the bipolar plate, M is the mass of the bipolar plate, T bp is the temperature of the bipolar plate, t is the time term, is the ohmic heat of the bipolar plate, is the heat conduction of the gas diffusion layer, To cool the bipolar plates, is the convective heat of the bipolar plates.

[0257] 5. The fourth step is to construct an equivalent network of thermal resistance and capacitance of the fuel cell and lithium battery hybrid system based on the heat flow method and Kirchhoff's law, complete the dynamic model of heat transfer, list the matrix expression of the constraints of the model, and calculate the heat transfer and conversion characteristics: Figure 4 Kirchhoff's law is used to establish an equivalent network of thermal resistance and capacitance, complete the dynamic model of heat transfer of fuel cell and lithium battery hybrid system, and list the matrix expression of model constraints as follows: Figure 5 , the model includes not only conduction but also considers other heat transfer modes such as convection, thus enabling accurate prediction and analysis of the dynamic response of the thermal interface at different time and space scales.

[0258] Thermal resistance and capacitance description of the fuel cell anode channel layer:

[0259] T gas,an,j +Q gas,an,j R gas,an,j =T cha,an (29)

[0260] Among them, T gas,an,j is the temperature of the anode gas in the jth channel, Q gas,an,j represents the heat of the anode gas in the jth channel, R gas,an,j is the thermal resistance of the anode gas in the jth channel, T cha,an is the overall temperature of the anode bipolar plate.

[0261] Description of thermal resistance and capacitance of the fuel cell cathode layer:

[0262] T gas,ca,j -Q gas,ca,j R gas,ca,j =T cha ,ca (30)

[0263] Among them, T gas,ca,j is the temperature of the cathode gas in the jth channel, Q gas,ca,j represents the heat of cathode gas in the jth channel, R gas,ca,j is the thermal resistance of the cathode gas in the jth channel, Tcha,ca is the overall temperature of the cathode bipolar plate.

[0264] Thermodynamic equation for fuel cell anode cooling:

[0265] T cw,in +ε cw,an -Q cool,sw R cool,sw =T sw,in (31)

[0266] Among them, T cw,in is the temperature of the fuel cell cooling water entering the fuel cell, ε cw,an is the thermodynamic potential of the fuel cell anode, Q cool,sw For cooling heat, R cool,sw is the cooling thermal resistance, T sw,in The temperature of the cooling water entering the lithium battery.

[0267] Fuel cell cathode cooling thermodynamic equation:

[0268] T cw,in +ε cw,ca -Q cool,sw R cool,sw =T sw,in (32)

[0269] Among them, T cw,in is the temperature of the fuel cell cooling water entering the fuel cell, ε cw,ca is the thermodynamic potential of the fuel cell cathode, Q cool,sw For cooling heat, R cool,sw is the cooling thermal resistance, T sw,in The temperature of the cooling water entering the lithium battery.

[0270] The thermal resistance and capacitance between the fuel cell anode and the environment are described as follows:

[0271] T env +Q hcv,cha R hcv,cha +Q gas,an,in R gas,an,in =T gas,an,in (33)

[0272] Among them, T env is the ambient temperature, Q hcv,cha is the convective heat transfer of the fuel cell bipolar plate, R hcv,cha is the convective heat transfer resistance of the fuel cell bipolar plate, Q gas,an,in is the heat of the anode gas entering, R gas,an,in is the thermal resistance of anode gas entering, T gas,an,in is the temperature of the anode gas entering the anode.

[0273] The thermal resistance and capacitance between the fuel cell cathode and the environment are described as follows:

[0274] T env +Q hcv,cha R hcv,cha +Q gas,ca,in R gas,ca,in =T gas ,ca,in (34)

[0275] Among them, T env is the ambient temperature, Q hcv,cha is the convective heat transfer of the fuel cell bipolar plate, R hcv,cha is the convective heat transfer resistance of the fuel cell bipolar plate, Q gas,ca,in is the heat of cathode gas entering, R gas,ca,in is the thermal resistance of cathode gas entering, T gas,ca,in is the temperature of the cathode gas entering the cathode.

[0276] The thermal resistance and capacitance description of the i-th single cell anode bipolar plate and lithium battery in the fuel cell:

[0277] T env +Q hcv,i R hcv,i -∑Q hcd,i R hcd,i -Q cool,abp R cool,abp +ε cw,i -Q cool,sw R cool,sw =T sw,in (35)

[0278] Among them, T env is the ambient temperature, Q hcv,i is the convective heat transfer of the i-th single battery, R hcv,i is the convection heat transfer resistance of the ith single cell, ∑Q hcd,i R hcd,i Q is the product of the heat conduction and thermal resistance of all i cells. cool,abp is the cooling heat of the anode bipolar plate, R cool,abp is the thermal resistance of the anode bipolar plate, ε cw,i is the cooling thermal potential of the ith battery, Q cool,sw Cooling heat for lithium batteries, R cool,sw is the thermal resistance of lithium battery cooling, T sw,in is the cooling water inlet temperature.

[0279] The thermal resistance and capacitance description of the cathode bipolar plate and lithium battery of the i-th single cell in the fuel cell:

[0280] T env +Q hcv,i R hcv,i -∑Q hcd,i Rhcd,i -Q cool,cbp R cool,cbp +ε cw,i -Q cool,sw R cool,sw =T sw,in (36)

[0281] Among them, T env is the ambient temperature, Q hcv,i is the convective heat transfer of the i-th single battery, R hcv,i is the convection heat transfer resistance of the ith single cell, ∑Q hcd,i R hcd,i Q is the product of the heat conduction and thermal resistance of all i cells. cool,cbp is the cooling heat of the cathode bipolar plate, R cool,cbp is the thermal resistance of the cathode bipolar plate, ε cw,i is the cooling thermal potential of the ith battery, Q cool,sw Cooling heat for lithium batteries, R cool,sw is the thermal resistance of lithium battery cooling, T sw,in is the cooling water inlet temperature.

[0282] 6. In Article 1, the different modes of the hybrid power system are: pure fuel cell power supply mode, fuel cell and lithium battery combined power supply mode and lithium battery charging power compensation mode.

[0283] 7. In the fifth step, the calculation results can obtain the dynamic response of the hybrid system heat transfer, the characterization of the system thermal management performance and the change law of each temperature node of the system.

[0284] 8. Dynamic results of system thermal management response under three different power supply modes:

[0285] Mode 1: The thermal response results of the system in pure PEMFC power supply mode are as follows Figure 6 As shown;

[0286] Mode 2: The thermal response results of the system PEMFC and LIB combined power supply operation mode are as follows Figure 7 As shown;

[0287] Mode 3: Thermal response analysis of the system LIB power compensation mode Figure 8 shown.

[0288] 9. Specific case data analysis is as follows:

[0289] 1) Figure 6It shows that the temperature response of the structural layer on the anode side shows a smooth transition trend with the change of load current. In the initial stage of 0-350s, the thermal response of various structural layers is more stable compared with the stage of 350-1200s. In addition, the adjacent structural layers receive heat through thermal conduction and convection, resulting in the peak interlayer temperature response on the anode side. The inflection point of the thermal response is at 350s, while the inflection point of the slope of the load current is at 300s, showing a significant difference between the thermal response sensitivity and the electrical response sensitivity.

[0290] 2) Figure 7 As the load current changes, the structural layer on the anode side shows a certain latent phenomenon under the influence of the overshoot current, but generally maintains a trend of smooth transition. The thermal response curvature values ​​between different structural layers show significant differences, and the anode gas diffusion layer shows the highest curvature value, indicating that its thermal response amplitude under overshoot load conditions has increased significantly. The anode bipolar plate layer shows a downward trend, while the proton exchange membrane layer still shows the largest temperature response amplitude, indicating that it has significant thermal response capabilities under high load conditions. In contrast, the curvature value of the proton exchange membrane layer is smaller, indicating that its thermal response sensitivity under overshoot load conditions is relatively low.

[0291] 3) Figure 8 It is indicated that under the influence of charging, the temperature changes of the structural layers on the anode side show a latent phenomenon, although a smooth transition is observed in the initial 0-85s interval, with a clear transition at the 85s mark. Specifically, the temperature change of the anode channel layer shows the highest curvature value, indicating that its thermal response amplitude increases significantly when facing the downstroke load. In contrast, the curvature value of the anode bipolar plate layer is the smallest, indicating that the thermal response amplitude is relatively small under the same conditions. In addition, the anode channel layer also records the highest temperature response amplitude.

[0292] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating a dynamic thermal management model of a fuel cell and lithium battery hybrid system, characterized in that: The steps include: S1. Perform mathematical deconstruction and dimensionality reduction reconstruction of heat transfer of fuel cell and lithium battery hybrid system, and build a one-dimensional dynamic model of heat transfer of fuel cell, lithium battery and system accessories based on dimensionality reduction reconstruction; S2. Assemble the model and establish the heat source model of the system; according to the assembly results, obtain the system energy conservation equation based on the law of conservation of energy, the law of conservation of mass, conduction and heat convection models; S3. Construct model constraints, and finally calculate the heat transfer and conversion characteristics under different system power supply modes, analyze the system at each key deconstruction node and their interactions, obtain the system heat transfer dynamic response, the system thermal management performance characterization and the change law of each temperature node of the system; In step S1, the one-dimensional dynamic model of heat transfer is a one-dimensional thermal resistance model under heat transfer, which satisfies the following formula: Wherein, the subscripts h and c represent the hot fluid and the cold fluid, G c is the heat capacity of the cold fluid, G h is the heat capacity of the hot fluid, and KA is the thermal conductivity of the heat exchange.

2. The calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system according to claim 1 is characterized in that: The heat transfer resistance of the fuel cell and lithium battery hybrid system includes gas thermal resistance, convection thermal resistance, thermal conduction thermal resistance, fuel cell cooling thermal resistance, lithium battery cooling thermal resistance, sensible heat humidity thermal resistance and latent heat humidity thermal resistance; The gas thermal resistance satisfies the following formula: Among them, R gas is the thermal resistance of any gas, G gas is the heat capacity of the gas, (KA) gas is the thermal conductivity of gas heat exchange; The convection thermal resistance satisfies the following formula: Among them, R hcv is any convection thermal resistance, h is the corresponding convection heat transfer coefficient, A i is any convective heat transfer area; The thermal resistance satisfies the following formula: Among them, R hcd is any thermal resistance, δ i is the corresponding thermal conductive surface thickness, A i is any heat conduction area, λ h,i is the thermal conductivity; The fuel cell cooling thermal resistance satisfies the following formula: Among them, R cool,fc is the cooling thermal resistance of the fuel cell, G bp is the heat capacity of the bipolar plate, G cw is the heat capacity of cooling seawater, (KA) cool Thermal conductivity for cooling heat exchange; The lithium battery cooling thermal resistance satisfies the following formula: Among them, R cool,cw is the cooling thermal resistance of the lithium battery, G cw is the heat capacity of cooling seawater, (KA) cool Thermal conductivity for cooling heat exchange; The sensible heat humidity thermal resistance satisfies the following formula: Among them, R h is the sensible heat and humidity thermal resistance, G c1 is the heat capacity of humidity 1, NTU e is the number of heat transfer units for the sensible heat of cooling; The latent heat humidity thermal resistance satisfies the following formula: Among them, R m is the latent heat humidity thermal resistance, G c2 is the heat capacity of humidity 2, NTU m is the number of heat transfer units for the latent heat of cooling.

3. The calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system according to claim 1 is characterized in that: In step S2, the heat source model includes heat generated by the fuel cell, heat dissipated by the fuel cell, heat generated by the lithium battery, heat dissipated by the lithium battery, net heat of gas, anode gas heat, cathode gas heat, convection heat, conduction heat, cooling heat of the fuel cell, cooling heat of the lithium battery, ohmic heat and activation heat.

4. The calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system according to claim 3 is characterized in that: The fuel cell power generation heat satisfies the following formula: in, is the average heat transfer rate of the fuel cell, is the molar flow rate of hydrogen consumption, is the higher calorific value of hydrogen, is the average power of the fuel cell; The heat dissipation of the fuel cell satisfies the following formula: in, is the average heat generated by the fuel cell, The gas heat of hydrogen, To cool down the heat, is convection heat; The heat generated by the lithium battery satisfies the following formula: in, is the average heat transfer rate of lithium battery, η B is the charging and discharging efficiency of lithium battery, sgn(P B ) is the symbol function, is the power of lithium battery; The heat dissipation of the lithium battery satisfies the following formula: in, is the heat dissipation of the lithium battery, Cooling heat from lithium batteries; The net heat of the gas satisfies the following formula: in, is the net heat of the gas, is the heat of gas outlet, is the heat of gas inlet; The anode gas heat satisfies the following formula: Q gas,an =(T cha,an -T gas,in,an ) / R gas,an ; Among them, Q gas,an is the anode gas heat, T cha,an is the anode channel layer temperature, T gas,in,an is the temperature of the anode gas entering the gas,an is the thermal resistance of the anode; The cathode gas heat satisfies the following formula: Q gas,ca =(T gas,in,ca -T cha,ca ) / R gas,ca ; Among them, Q gas,ca is the cathode gas heat, T gas,in,ca is the cathode channel layer temperature, T cha,ca is the temperature of the cathode gas entering, R gas,ca is the thermal resistance of the cathode; The convective heat satisfies the following formula: Q hcv,i =(T i+1 -T i ) / R hcv,i ; Among them, Q hcv,i is the convective heat of single cell i, T i+1 is the overall temperature of the single cell i+1, T i is the overall temperature of single cell i, R hcv,i is the overall convection thermal resistance of single cell i; The conduction heat satisfies the following formula: Q hcd,i =(T i+1 -T i ) / R hcd,i ; Among them, Q hcd,i is the conduction heat of single cell i, T i+1 is the overall temperature of the single cell i+1, T i is the overall temperature of single cell i, R hcd,i is the overall conduction thermal resistance of single cell i; The cooling heat of the fuel cell satisfies the following formula: Q cool,bp =(T bp -T cw ) / R cool,bp ; Among them, Q cool,bp is the cooling heat of the bipolar plate, T bp is the temperature of the bipolar plate, T cw is the cooling temperature of the single cell, R cool,bp is the cooling thermal resistance of the bipolar plate; The cooling heat of the lithium battery satisfies the following formula: Q cool,sw =(T cw,out -T sw,in ) / R cool,sw ; Among them, Q cool,sw is the cooling heat of the lithium battery, T cw,out is the fuel cell cooling outlet temperature, T sw,in is the lithium battery cooling inlet temperature, R cool,sw is the cooling thermal resistance of the lithium battery; The ohmic heat satisfies the following formula: in, is the ohmic heat of single cell i, is the square of the fuel cell current, A i is the cross-sectional area of ​​single cell i, ASR i is the area specific resistance of single cell i; The activation heat satisfies the following formula: in, is the activation heat of the fuel cell, I FC is the fuel cell current, V act is the activation voltage.

5. The calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system according to claim 1 is characterized in that: In step S2, the system energy conservation equation includes the energy conservation of the fuel cell proton membrane, the energy conservation of the fuel cell anode catalyst layer, the energy conservation of the fuel cell cathode catalyst layer, the energy conservation of the fuel cell microporous layer, the energy conservation of the fuel cell gas diffusion layer, the energy conservation of the fuel cell channel layer and the energy conservation of the fuel cell bipolar plate.

6. The calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system according to claim 5 is characterized in that: The fuel cell proton membrane energy conservation satisfies the following formula: Where C is the equivalent specific heat capacity of the membrane, M is the mass of the membrane, T m is the temperature of the film, t is the time term, is the ohmic heat of the membrane, is the heat conduction between the cathode catalyst layer and the membrane, is the heat conduction of the film, is the convective heat of the membrane; The energy conservation of the anode catalyst layer of the fuel cell satisfies the following formula: Where C is the equivalent specific heat capacity of the anode catalyst layer, M is the mass of the anode catalyst layer, T acl is the temperature of the anode catalyst layer, t is the time term, is the ohmic heat of the anode catalyst layer, is the heat conduction of the film, is the heat conduction of the anode catalyst layer, is the convection heat of the anode catalyst layer; The energy conservation of the cathode catalyst layer of the fuel cell satisfies the following formula: Where C is the equivalent specific heat capacity of the cathode catalyst layer, M is the mass of the cathode catalyst layer, T ccl is the temperature of the cathode catalyst layer, t is the time term, is the ohmic heat of the cathode catalyst layer, is the activation heat of the cathode catalyst layer, is the heat conduction between the cathode catalyst layer and the membrane, It is the heat conduction between the cathode catalyst layer and the cathode side microporous layer. is the convective heat of the cathode catalyst layer; The energy conservation of the microporous layer of the fuel cell satisfies the following formula: Where C is the equivalent specific heat capacity of the microporous layer, M is the mass of the microporous layer, and T mpl is the temperature of the microporous layer, t is the time term, is the ohmic heat of the microporous layer, is the heat conduction of the catalyst layer, is the heat conduction of the microporous layer, is the convective heat of the microporous layer; The energy conservation of the fuel cell gas diffusion layer satisfies the following formula: Where C is the equivalent specific heat capacity of the gas diffusion layer, M is the mass of the gas diffusion layer, T gdl is the temperature of the gas diffusion layer, t is the time term, is the ohmic heat of the gas diffusion layer, is the heat conduction of the microporous layer, is the heat conduction of the gas diffusion layer, is the convective heat of the gas diffusion layer; The energy conservation of the fuel cell channel layer satisfies the following formula: Where C is the equivalent specific heat capacity of the channel layer, M is the mass of the channel layer, T cha is the temperature of the channel layer, t is the time term, To remove heat from the gas, For the gas to enter the heat, is the convective heat of the channel layer; The energy conservation of the fuel cell bipolar plate satisfies the following formula: Where C is the equivalent specific heat capacity of the bipolar plate, M is the mass of the bipolar plate, T bp is the temperature of the bipolar plate, t is the time term, is the ohmic heat of the bipolar plate, is the heat conduction of the gas diffusion layer, To cool the bipolar plates, is the convective heat of the bipolar plates.

7. The calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system according to claim 1 is characterized in that: In step S3, an equivalent network of thermal resistance and capacitance of the fuel cell and lithium battery hybrid system is constructed based on the heat flow method and Kirchhoff's law, a dynamic model of heat transfer of the fuel cell and lithium battery hybrid system is completed, a matrix expression of the constraint conditions of the model is listed, and heat transfer and conversion characteristics are calculated; the model includes conduction and convection heat transfer modes, so as to predict and analyze the dynamic response of the thermal interface at different time and space scales.

8. The calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system according to claim 7 is characterized in that: The thermal resistance and capacitance of the anode channel layer of the fuel cell satisfy the following formula: T gas,an,j +Q gas,an,j R gas,an,j =T cha,an ; Among them, T gas,an,j is the temperature of the anode gas in the jth channel, Q gas,an,j is the heat of the anode gas in the jth channel, R gas,an,j is the thermal resistance of the anode gas in the jth channel, T cha,an is the overall temperature of the anode bipolar plate; The thermal resistance and capacitance of the cathode layer of the fuel cell satisfy the following formula: T gas,ca,j -Q gas,ca,j R gas,ca,j =T cha,ca ; Among them, T gas,ca,j is the temperature of the cathode gas in the jth channel, Q gas,ca,j is the heat of cathode gas in the jth channel, R gas,ca,j is the thermal resistance of the cathode gas in the jth channel, T cha,ca is the overall temperature of the cathode bipolar plate; The fuel cell anode cooling thermodynamic equation satisfies the following formula: T cw,in +ε cw,an -Q cool,sw R cool,sw =T sw,in ; Among them, T cw,in is the temperature of the fuel cell cooling water entering the fuel cell, ε cw,an is the thermodynamic potential of the fuel cell anode, Q cool,sw For cooling heat, R cool,sw is the cooling thermal resistance, T sw,in The temperature of the cooling water entering the lithium battery; The fuel cell cathode cooling thermodynamic equation satisfies the following formula: T cw,in +ε cw,ca -Q cool,sw R cool,sw =T sw,in ; Among them, T cw,in is the temperature of the fuel cell cooling water entering the fuel cell, ε cw,ca is the thermodynamic potential of the fuel cell cathode, Q cool,sw For cooling heat, R cool,sw is the cooling thermal resistance, T sw,in The temperature of the cooling water entering the lithium battery; The thermal resistance and capacitance between the fuel cell anode and the environment satisfy the following formula: T env +Q hcv,cha R hcv,cha +Q gas,an,in R gas,an,in =T gas,an,in ; Among them, T env is the ambient temperature, Q hcv,cha is the convective heat transfer of the fuel cell bipolar plate, R hcv,cha is the convective heat transfer resistance of the fuel cell bipolar plate, Q gas,an,in is the heat of the anode gas entering, R gas,an,in is the thermal resistance of anode gas entering, T gas,an,in is the temperature of the anode gas entering; The thermal resistance and capacitance between the fuel cell cathode and the environment satisfy the following formula: T env +Q hcv,cha R hcv,cha +Q gas,ca,in R gas,ca,in =T gas,ca,in ; Among them, T env is the ambient temperature, Q hcv,cha is the convective heat transfer of the fuel cell bipolar plate, R hcv,cha is the convective heat transfer resistance of the fuel cell bipolar plate, Q gas,ca,in is the heat of cathode gas entering, R gas,ca,in is the thermal resistance of cathode gas entering, T gas,ca,in is the temperature of cathode gas entering; The thermal resistance and capacitance of the anode bipolar plate of the i-th single cell in the fuel cell and the lithium battery satisfy the following formula: T env +Q hcv,i R hcv,i -∑Q hcd,i R hcd,i -Q cool,abp R cool,abp +ε cw,i -Q cool,sw R cool,sw =T sw,in ; Among them, T env is the ambient temperature, Q hcv,i is the convective heat transfer of the i-th single battery, R hcv,i is the convection heat transfer resistance of the ith single cell, ∑Q hcd,i R hcd,i Q is the product of the heat conduction and thermal resistance of all i cells. cool,abp is the cooling heat of the anode bipolar plate, R cool,abp is the thermal resistance of the anode bipolar plate, ε cw,i is the cooling thermal potential of the ith battery, Q cool,sw Cooling heat for lithium batteries, R cool,sw is the thermal resistance of lithium battery cooling, T sw,in is the temperature of cooling water entering; The thermal resistance and capacitance of the cathode bipolar plate and the lithium battery of the i-th single cell in the fuel cell satisfy the following formula: T env +Q hcv,i R hcv,i -∑Q hcd,i R hcd,i -Q cool,cbp R cool,cbp +ε cw,i -Q cool,sw R cool,sw =T sw,in ; Among them, T env is the ambient temperature, Q hcv,i is the convective heat transfer of the i-th single battery, R hcv,i is the convection heat transfer resistance of the ith single cell, ∑Q hcd,i R hcd,i Q is the product of the heat conduction and thermal resistance of all i cells. cool,cbp is the cooling heat of the cathode bipolar plate, R cool,cbp is the thermal resistance of the cathode bipolar plate, ε cw,i is the cooling thermal potential of the ith battery, Q cool,sw Cooling heat for lithium batteries, R cool,sw is the thermal resistance of lithium battery cooling, T sw,in is the cooling water inlet temperature.

9. The calculation method of the dynamic thermal management model of the fuel cell and lithium battery hybrid power system according to claim 1, characterized in that: In step S3, different modes of the hybrid power system include: a pure fuel cell power supply mode, a fuel cell and lithium battery combined power supply mode, and a lithium battery charging power compensation mode.

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