Thermal management system part type selection method

Abstract

The invention discloses a thermal management system part type selection method, which belongs to the technical field of electric automobiles and comprises the following steps: dynamically calculating cooling and heating loads of a thermal management system; refrigerant side thermodynamic cycle parameters are matched; integrating and selecting key components of the thermal management system; constructing a multi-objective optimization function, and realizing parameter matching and capacity checking of a plurality of components; verifying the robustness and economy of a model selection scheme for multi-mode thermal management coupling under typical working conditions; according to the model selection method established based on dynamic coupling analysis, self-adaptive matching of a dynamic load model and refrigerant parameters is considered, and both precision and efficiency are considered; multi-loop coupling analysis is supported, the feasibility of redundant configuration and complex architecture can be quickly evaluated, multi-dimensional collaborative optimization is realized, and the trial and error cost is reduced; the method is suitable for forward design and iterative optimization of the new energy automobile thermal management system, the development cost can be remarkably reduced, and the system energy efficiency can be improved.

Description

Technical Field

[0001] The invention relates to the field of electric vehicle technology, specifically a method for selecting components in a thermal management system. Background Technology

[0002] Electric vehicles (EVs) have become a core direction for the development of the automotive industry due to their advantages such as zero emissions and high energy efficiency. However, the thermal management system of EVs faces more severe challenges than that of traditional gasoline vehicles: First, the power battery generates a large amount of heat during charging and discharging, and insufficient heat dissipation will lead to battery performance degradation or even thermal runaway; second, the efficient cooling requirements of the motor and electronic control unit directly affect the stability of the vehicle's power output; third, the thermal comfort requirements of the passenger compartment need to be achieved through precise control of the cooling and heating systems. In addition, EVs lack engine waste heat, and heating in winter relies on electric heating or heat pump systems, further exacerbating the contradiction between energy consumption and range. Therefore, developing an efficient and integrated thermal management system has become the key to improving the overall performance of EVs.

[0003] In the development of thermal management systems, traditional prototype testing methods for selection are gradually being replaced by simulation modeling techniques due to their high cost and long development cycle. However, existing simulation models are mostly built based on the component lumped parameter method, which has significant limitations: First, lumped models of key components such as heat exchangers cannot accurately reflect actual heat transfer characteristics, especially the flow channel structure and dynamic changes in the heat transfer coefficient of parallel flow heat exchangers; Second, system-level simulations lack refined coupling analysis of refrigerant-side parameters (such as evaporation temperature and subcooling) and component performance (such as compressor volumetric efficiency and electronic expansion valve flow coefficient), resulting in significant deviations between the selection results and actual operating conditions. In addition, the load superposition and energy interaction of various subsystems (such as battery cooling circuits, heat pump refrigeration circuits, and motor heat dissipation circuits) in complex systems have not yet formed a standardized calculation process, further increasing the difficulty of selection. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a method for selecting components in a thermal management system.

[0005] To achieve the above objectives, the technical solution of the invention is: a method for selecting components of a thermal management system, comprising the following steps: Step 1: Refined modeling and calculation of cooling and heating loads. Based on the harmonic response method and experimental correction data, dynamic models of cooling and heating loads for the cockpit, battery unit and motor control unit are established by integrating the vehicle body heat transfer coefficient, fresh air infiltration, equipment heat generation, passenger body heat dissipation and solar radiation from the glass. Step 2: Matching and calculating thermodynamic cycle parameters on the refrigerant side. Combining the pressure-enthalpy diagram and the refrigerant property databases R134a and R407c, the evaporation temperature, condensation pressure, subcooling and superheat are determined by formula calculation to optimize the system energy efficiency ratio and verify the stability of the operating conditions by formula. Step 3: Integration and selection of key components of the thermal management system. This involves integrating the compressor displacement and power model, the heat exchanger heat transfer and flow resistance correlation equation, and the electronic expansion valve flow and pressure drop characteristic curve to construct a multi-objective optimization function and optimize the selection. Step four: Multi-mode thermal management coupling verification. For summer cooling, winter heating and battery fast charging conditions, the robustness of the selected scheme is verified by analyzing component selection cases, dynamically evaluating system flow distribution, temperature fluctuation and energy consumption performance.

[0006] Furthermore, in step one, the cooling load of the cockpit consists of heat conduction from the vehicle body, solar radiation from the glass, heat dissipation from the passenger's body, heat generation from in-vehicle instruments and equipment, and fresh air load, as specified in the formula below. .

[0007] Furthermore, in step one, the thermal load of the cockpit... The state equation derived using the harmonic response method is as follows: ; ; ; ; ; ; ; .

[0008] Furthermore, in step one, the heat dissipation load of the battery cells needs to be calculated separately for the heat of reaction. Polarization heat heat of side reactions Joule fever Finally, add them up to get the total heat production rate. The state equation for the heat generation of the battery cell, derived based on the Bernadi heat generation model, is as follows: ; ; ; ; .

[0009] Furthermore, in step six, the formula for calculating the heating load of the battery cell is as follows: ; .

[0010] Furthermore, in step one, the heat generated by the motor is calculated using a simplified method based on the motor's efficiency, as shown in the following formula: .

[0011] Furthermore, in step two, the density, specific enthalpy, kinematic viscosity, and specific heat capacity of the refrigerant inside the pipe and the fluid outside the pipe are all queried in real time using the Refprop tool. The saturation pressure at a specific temperature can be obtained by consulting the working fluid thermodynamic property table or by using the Refprop tool. The formula used by the Refprop tool is as follows: .

[0012] Furthermore, in step two, the evaporation pressure and condensation pressure are determined, with the evaporation pressure being 0.2-0.4 MPa and the condensation pressure being 0.9-2.5 MPa; the subcooling is determined, and in practical applications, the difference between the temperature at the condenser outlet and the average temperature in the middle is used.

[0013] Furthermore, in step two, the system component capacity is calculated using the following formula: ; ; ; ; ; ; .

[0014] Furthermore, in step four, the analysis of component selection cases, dynamic evaluation of system flow distribution, temperature fluctuation and energy consumption performance, and verification of the robustness of the selection scheme during multi-mode thermal management coupling verification are all based on the thermal load of the cockpit, the thermal load of the battery, and the thermal load of the motor unit.

[0015] Based on the above settings, this invention proposes a component selection method based on dynamic analysis of cooling and heating loads. This method innovatively decomposes the cooling and heating loads of the cockpit, battery, and motor control unit into independent calculation modules. It combines methods such as harmonic response method, air exchange rate method, and multiphysics model of battery heat generation to achieve accurate load quantification. Through pressure-enthalpy diagram operating point analysis and iterative matching of refrigerant property parameters, it optimizes core parameters such as compressor displacement and heat exchanger heat transfer. Furthermore, it introduces a flow resistance-flow rate collaborative algorithm for electronic expansion valves and water pumps to ensure component compatibility under dynamic operating conditions. Compared to existing technologies, this invention significantly improves selection accuracy, reduces system redundancy energy consumption, and provides methodological support for the integrated design and performance optimization of multi-mode thermal management systems.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Based on the harmonic response method and the air exchange rate method, combined with the vehicle body heat transfer dynamic characteristics and passenger compartment air leakage correction, the cooling and heating load of the cockpit is quantified. By treating the comprehensive temperature of the outside air as a periodic external disturbance and analyzing the attenuation effect and phase delay characteristics of temperature fluctuation, accurate modeling of the vehicle body heat storage and heat transfer dynamic process is achieved. In particular, for the battery cooling and heating load, a multi-source heat generation model including reaction heat, polarization heat and Joule heat is constructed.

[0017] 2. Using a combined analysis method of pressure-enthalpy diagram (ph diagram) and thermodynamic cycle, and combining refrigerant property databases such as R134a and R407c, key parameters such as evaporation temperature, condensation temperature, and subcooling are accurately matched. For heat exchanger selection, a collaborative model of heat transfer coefficient and flow resistance of parallel flow heat exchanger is established. Based on heat load demand and air-coolant temperature difference, structural parameters such as heat exchanger windward area, core thickness, and heat dissipation area are derived in reverse. Multi-condition verification is carried out in conjunction with the manufacturer's performance parameter table.

[0018] 3. By establishing a cooling and heating load calculation module, a refrigerant parameter matching module, and a component performance database, a standardized selection process is formed. This method can be adapted to complex multi-mode thermal management architectures (such as heat pump-battery cooling coupling systems and waste heat recovery systems), ensuring optimal compatibility and energy efficiency of components under dynamic operating conditions, and providing systematic technical support for the integrated design, performance verification, and cost control of electric vehicle thermal management systems. Attached Figure Description

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] Figure 1 This is a diagram showing the selection steps for each component of the thermal management system of this invention; Figure 2 This is the pressure-enthalpy diagram of the thermodynamic cycle state of the present invention; Figure 3 This is the cyclic pressure-enthalpy diagram of the air conditioning system of the present invention; Figure 4 This is the compressor model of the present invention; Figure 5 This is a diagram showing the performance parameters of the in-vehicle condenser of this invention; Figure 6 This is a performance parameter diagram of the external heat exchanger of the present invention; Figure 7 This is the electronic expansion valve model of the present invention; Figure 8 This is a performance curve diagram of the water pump of the present invention; Figure 9 This is a parameter diagram of a selection case for the present invention; Figure 10 This invention relates to the refrigerant-side parameter matching of electric vehicles; Figure 11 This is the pressure-enthalpy diagram of the present invention under summer and winter operating conditions; Figure 12 This is the characteristic curve of the electronic fan selected as an example in this invention. Detailed Implementation

[0021] like Figure 1-12 As shown, a method for selecting components of a thermal management system is presented. This method for selecting the thermal management system of an electric vehicle is implemented through a specific selection formula. To verify the accuracy of the selection method, a specific case is used for verification. The electric vehicle thermal management system selection method described in this embodiment is as follows: Figure 1 As shown, the selection method includes: 1. Compressor selection, 2. Heat exchanger selection, 3. Electronic expansion valve selection, 4. Electronic water pump selection, 5. Electronic fan selection, and 6. PTC selection. The specific steps are as follows: Step 1: Refined modeling and calculation of cooling and heating loads. The cooling load of the cockpit mainly consists of heat conduction from the vehicle body (roof, floor, glass, side walls, etc.), solar radiation from the glass, heat dissipation from passengers, heat generation from in-vehicle instruments and equipment, and fresh air load. The specific formula is as follows: ; in, This represents the total cooling load of the car's air conditioning system. Conducting heat for the car body, For solar radiation from glass; To reduce heat loss from the passenger's body To generate heat for instruments and equipment inside the vehicle. The value is the fresh air load, and A represents the parameter corresponding to different vehicle models, with a value range of 0.5-2. thermal load of the cockpit The state equation derived using the harmonic response method is as follows: ; ; ; ; ; ; ; ; In the above formula, Heat loss due to heat transfer to the vehicle body; K is the heat transfer coefficient of the vehicle body structure; F represents the heat transfer area of ​​the vehicle body structure; The temperature difference between the interior and exterior of the vehicle; , These refer to the calculated indoor air temperature and outdoor air temperature of an air-conditioned vehicle during winter. , The convective heat transfer coefficients are the inner and outer surfaces of the vehicle interior. The sum of the thermal resistances of each layer of material in the vehicle body structure is given by α, where α is a parameter with a value ranging from 3.3 to 3.6. b is a constant whose value is related to the airflow and temperature difference inside the vehicle. When the air is naturally circulating, b takes the range of 2.67-3.26. c is a parameter, with a value range of 0.09-0.11; d is a parameter, with a value range of 1-1.2; e is a parameter, with a value range of 0.2-0.3; n is a parameter, and its value ranges from 3 to 5; m is a parameter, with a value range of 11.5-13.5; v is the component of the superimposed speed of the car and the wind speed along the outer wall of the car. The heat consumed is used to preheat the cold air seeping in through the gaps in doors and windows; This is a parameter, with a value range of 0.25-0.3; The air exchange rate in the vehicle compartment, ranging from 0.5 to 1.0. This refers to the internal volume of the vehicle interior; For fresh air volume; air density; These are the enthalpy values ​​of air inside and outside the vehicle, respectively. For fresh air load; Heat dissipation from the passenger's body; To generate heat for instruments and equipment inside the vehicle; A represents the parameters corresponding to different vehicle models, with a value range of 0.5-2; The heat dissipation load of each battery cell needs to be calculated separately for the heat of reaction. Polarization heat heat of side reactions Joule fever Finally, add them up to get the total heat production rate. The state equation for the heat generation of the battery cell, derived based on the Bernadi heat generation model, is as follows: ; ; ; ; ; It is the heat of reaction; In the above formula, n is the number of battery cells; m is the mass of the battery electrode; Total heat of reaction in the battery; I represents the charging and discharging current; M is the molar mass; F is Faraday's constant; It is the heat of polarization; This is the internal resistance to polarization; This is the heat of the battery's side reaction; A represents the parameters corresponding to different vehicle models, with a value range of 0.5-2; The formula for calculating the heating load of the battery cell is as follows: ; ; In the above formula, Preheat the battery; Specific heat capacity of the battery; For the quality of the battery; For the temperature rise of the battery; Let be the specific heat capacity of the i-th material in the battery cell; Let be the mass of the i-th material in the battery cell; For the quality of the battery cell; The heat generated by the motor is calculated using a simplified method based on the motor's efficiency. The formula is as follows: ; In the above formula, This is the rated power of the motor; X is the motor efficiency; X is the motor load factor, which represents the ratio of the motor's actual power to its rated power.

[0022] Step 2: Matching and calculating thermodynamic cycle parameters on the refrigerant side. Combining the pressure-enthalpy diagram and the refrigerant property databases R134a and R407c, the evaporation temperature, condensation pressure, subcooling and superheat are determined by formula calculation to optimize the system energy efficiency ratio and verify the stability of the operating conditions by formula. The determination of evaporation temperature and condensation pressure needs to be combined with Figure 2 and Figure 3 The operating parameters, including the density, specific enthalpy, kinematic viscosity, and specific heat capacity of the refrigerant inside the pipe and the fluid outside, can be queried in real time using the Refprop tool. The saturation pressure at a specific temperature can be found by consulting the working fluid thermophysical property table or by using the Refprop tool. The formulas used in the Refprop tool are as follows: ; P is the saturation pressure we are looking for; T is temperature; X is the evaporation temperature of the working fluid; It represents the mass fraction of the gas, where 1 indicates that the working medium is in a saturated state, and E is the name of the working medium. Evaporation pressure and condensation pressure: evaporation pressure is taken as 0.2-0.4 MPa, and condensation pressure is taken as 0.9-2.5 MPa; determine the subcooling: in practical applications, the difference between the temperature at the condenser outlet and the average temperature in the middle is used; The system component capacity is calculated using the following formula: ; ; ; ; ; ; ; Mass flow rate in the air conditioning circuit; The actual selected heating and cooling loads; They are respectively Figure 2 Pressure-enthalpy diagram and Enthalpy value at the point; This is the total heat of reaction in the battery; K is a correction factor, with a value ranging from 1.05 to 1.15; V represents the compressor displacement; The volumetric efficiency of the compressor, with a value ranging from 0.7 to 0.9; N is the compressor speed, with a value ranging from 1000 to 4500. for Figure 2 Pressure-enthalpy diagram Refrigerant density at the location; This refers to the compressor's compression power. For pressure-enthalpy diagram Enthalpy value at the point; This refers to the compressor shaft power. The mechanical efficiency of the compressor, with a value ranging from 0.7 to 0.8; , These are the heat loads of the condenser, evaporator, and heat exchanger (battery pack cooler, battery cooler), respectively.

[0023] Step 3: Integration and selection of key components of the thermal management system. This involves integrating the compressor displacement and power model, the heat exchanger heat transfer and flow resistance correlation equation, and the electronic expansion valve flow and pressure drop characteristic curve to construct a multi-objective optimization function and optimize the selection. Currently, scroll compressors are widely used in electric vehicle air conditioning systems. The specific working principle will not be elaborated here, but volumetric efficiency is typically used. isentropic efficiency and mechanical efficiency Three parameters are used to describe the performance of refrigerant gas in the compressor. This embodiment will use a commonly used compressor model, such as... Figure 4 To demonstrate the definitions of these three efficiencies; The relevant parameters involved in compressor selection are calculated using the following formulas: ; The meanings and units of each physical quantity in formulas (1)-(3) are shown in the table below: ; The relevant parameters involved in heat exchanger selection are calculated using the following formulas: ; The meanings and units of each physical quantity in formulas (4)-(8) are shown in the table below: ; In actual production, heat exchanger manufacturers design reasonable solutions based on parameters such as the type of refrigerant, heat exchange capacity, and flow resistance limitations required by the user. Figure 5 and Figure 6 Performance parameters of heat exchangers for electric vehicle heat pump systems using R134a as the working fluid; Electronic expansion valve model such as Figure 7 The voltage or current applied to the expansion valve can be controlled by the electrical signal generated by the adjusted parameter, thereby achieving the purpose of regulating the mass flow rate. The relevant parameters involved in the selection of electronic expansion valves are calculated by the following formula: ; The meanings and units of each physical quantity in formulas (9)-(13) are shown in the table below: ; The relevant parameters involved in the selection of electronic water pumps are calculated using the following formulas: ; The meanings and units of each physical quantity in formulas (14)-(18) are shown in the table below: ; In practical applications, the efficiency of a cooling water pump initially increases with the increase of the pump flow rate, but then begins to decrease after reaching a certain value. Therefore, when designing a control strategy, it is important to take advantage of this characteristic of the pump to ensure that it operates within its highest efficiency range. Figure 8 Performance curve of an 80W water pump; The relevant parameters involved in the selection of electric fans are calculated using the following formulas: ; The meanings and units of each physical quantity in formulas (19)-(24) are shown in the table below: ; The relevant parameters involved in PTC selection are calculated using the following formulas: ; in, This is the required heating amount (W). It is the cockpit heat load (W). It is the battery thermal load (W), and K is the safety factor.

[0024] Step 4: Multi-mode thermal management coupling verification. For summer cooling, winter heating and battery fast charging conditions, the robustness of the selection scheme is verified by analyzing component selection cases, dynamically evaluating system flow distribution, temperature fluctuation and energy consumption performance. by Figure 9 Taking the cooling and heating loads of the cockpit, the cooling and heating loads of the battery, and the heating load of the motor unit as examples, parameter matching is performed. When matching the refrigerant side parameters of an electric vehicle, it is necessary to determine the evaporation and condensation temperatures, as well as the subcooling at the condenser outlet and the superheat at the evaporator outlet, under different operating conditions. Figure 10 As shown, following step two, determine the four points on the pressure-enthalpy diagram for summer and winter operating conditions respectively. Figure 11 As shown, calculate the system component capacity: ; ; Select a larger mass flow rate value to calculate the compressor displacement: ; Calculate the work done by the compressor: ; Calculate the maximum heat dissipation of the condenser: ; The selection of electronic expansion valves can be completed by inputting known parameters such as refrigerant type, condensing temperature, evaporating temperature, subcooling, superheating, and cooling capacity into a pre-program. The PTC selection takes into account the thermal requirements of the battery and the passenger compartment. The battery is 3400W and the passenger compartment is 5000W. Instead of choosing an 8400W electric heater, the heat of the passenger compartment is provided by the PTC and the heat pump air conditioning system. The empirical formula is the heat load of the battery plus 25% of the heat load of the passenger compartment. Finally, a 5000W electric heater was selected. The selection of heat exchangers can only be based on the maximum required heat exchange power to initially select a suitable model. After the initial selection is completed, simulation and other methods should be used to observe whether it can meet the corresponding thermal management requirements. It is unrealistic to directly select the corresponding heat exchanger structural parameters based on known conditions. For refrigerant-side heat exchangers, the evaporator is selected according to the cockpit cooling load of 4300W, the condenser is selected according to the maximum heat dissipation of the overall system of 9615.67W, and the chiller is selected according to the maximum cooling load of the battery of 4000W. For water-side radiators, the selection is based on the maximum cooling load required by the motor of 3900W. If the PTC uses the same radiator as the motor, the radiator is selected based on the maximum value of the above two conditions, and a 5000W radiator is selected. The selection of an electric fan is mainly based on the fan's airflow and pressure rise: ; The pressure rise requirement of the electric fan is related to the air-side pressure drop of the heat exchanger, which is provided by the supplier. The final selected electric fan data is as follows: Figure 12 As shown; The selection of a water-side electric water pump mainly depends on the pump's power and the loop flow rate: ; The power of an electric water pump is obtained from the pressure drop and flow rate of the entire circuit in which the pump is located: ; The voltage drop across the entire circuit is typically determined through simulation. In this case, the voltage drop is 2.73 bar. Therefore, the pump power is: ; The final selected water pump has a power of 40W and a displacement of 5cc.

[0025] The above description is merely an illustrative embodiment of the invention and is not intended to limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the invention should fall within the scope of protection of the invention.

Claims

1. A method for selecting components in a thermal management system, characterized in that, Includes the following steps: Step 1: Refined modeling and calculation of cooling and heating loads. Based on the harmonic response method and experimental correction data, dynamic models of cooling and heating loads for the cockpit, battery unit and motor control unit are established by integrating the vehicle body heat transfer coefficient, fresh air infiltration, equipment heat generation, passenger body heat dissipation and solar radiation from the glass. Step 2: Matching and calculating thermodynamic cycle parameters on the refrigerant side. Combining the pressure-enthalpy diagram and the refrigerant property databases R134a and R407c, the evaporation temperature, condensation pressure, subcooling and superheat are determined by formula calculation to optimize the system energy efficiency ratio and verify the stability of the operating conditions by formula. Step 3: Integration and selection of key components of the thermal management system. This involves integrating the compressor displacement and power model, the heat exchanger heat transfer and flow resistance correlation equation, and the electronic expansion valve flow and pressure drop characteristic curve to construct a multi-objective optimization function and optimize the selection. Step four: Multi-mode thermal management coupling verification. For summer cooling, winter heating and battery fast charging conditions, the robustness of the selected scheme is verified by analyzing component selection cases, dynamically evaluating system flow distribution, temperature fluctuation and energy consumption performance.

2. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step one, the cooling load of the cockpit consists of heat conduction from the vehicle body, solar radiation from the glass, heat dissipation from the passengers' bodies, heat generation from the instruments and equipment inside the vehicle, and fresh air load, as specified in the formula. ； in, This represents the total cooling load of the car's air conditioning system. Conducting heat for the car body, For solar radiation from glass; To reduce heat loss from the passenger's body To generate heat for instruments and equipment inside the vehicle. The value is the fresh air load, and A represents the parameter corresponding to different vehicle models, with a value range of 0.5-2.

3. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step one, the thermal load of the cockpit The state equation derived using the harmonic response method is as follows: ； ； ； ； ； ； ； ； in Heat loss due to heat transfer to the vehicle body; K is the heat transfer coefficient of the vehicle body structure; F represents the heat transfer area of ​​the vehicle body structure; The temperature difference between the interior and exterior of the vehicle; , These refer to the calculated indoor air temperature and outdoor air temperature of an air-conditioned vehicle during winter. , The convective heat transfer coefficients are the inner and outer surfaces of the vehicle interior. The sum of the thermal resistances of each layer of material in the vehicle body structure is given by α, where α is a parameter with a value ranging from 3.3 to 3.

6. b is a constant whose value is related to the airflow and temperature difference inside the vehicle. When the air is naturally circulating, b takes the range of 2.67-3.

26. c is a parameter, with a value range of 0.09-0.11; d is a parameter, with a value range of 1-1.2; e is a parameter, with a value range of 0.2-0.3; n is a parameter, and its value ranges from 3 to 5; m is a parameter, with a value range of 11.5-13.5; v is the component of the superimposed speed of the car and the wind speed along the outer wall of the car. The heat consumed is used to preheat the cold air seeping in through the gaps in doors and windows; This is a parameter, with a value range of 0.25-0.3; The air exchange rate in the vehicle compartment, ranging from 0.5 to 1.

0. This refers to the internal volume of the vehicle interior; For fresh air volume; air density; These are the enthalpy values ​​of air inside and outside the vehicle, respectively. For fresh air load; Heat dissipation from the passenger's body; To generate heat for instruments and equipment inside the vehicle; A represents the parameters corresponding to different vehicle models, with a value range of 0.5-2.

4. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step one, the heat dissipation load of the battery cells needs to be calculated separately for the reaction heat. Polarization heat heat of side reactions Joule fever Finally, add them up to get the total heat production rate. The state equation for the heat generation of the battery cell, derived based on the Bernadi heat generation model, is as follows: ； ； ； ； ； It is the heat of reaction; n represents the number of individual battery cells; m is the mass of the battery electrode; Total heat of reaction in the battery; I represents the charging and discharging current; M is the molar mass; F is Faraday's constant; It is the heat of polarization; This is the internal resistance to polarization; This is the heat generated by the side reaction of the battery; A represents the parameters corresponding to different vehicle models, with a value range of 0.5-2.

5. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step one, the formula for calculating the heating load of the battery cell is as follows: ； ； Preheat the battery; Specific heat capacity of the battery; For the quality of the battery; For the temperature rise of the battery; Let be the specific heat capacity of the i-th material in the battery cell; Let be the mass of the i-th material in the battery cell; This refers to the quality of the battery cell.

6. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step one, the heat generated by the motor is calculated using a simplified method based on the motor's efficiency, as shown in the following formula: ； This is the rated power of the motor; It refers to motor efficiency; X is the motor load factor, which represents the ratio of the motor's actual power to its rated power.

7. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step two, the density, specific enthalpy, kinematic viscosity, and specific heat capacity of the refrigerant inside the pipe and the fluid outside the pipe are all queried in real time using the Refprop tool. The saturation pressure at a specific temperature can be obtained by consulting the working fluid thermodynamic property table or by using the Refprop tool. The formula used by the Refprop tool is as follows: ； P is the saturation pressure we are looking for; T is temperature; X is the evaporation temperature of the working fluid; It represents the mass fraction of the gas, where 1 indicates that the working medium is in a saturated state, and E is the name of the working medium.

8. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step two, the evaporation pressure and condensation pressure are determined, with the evaporation pressure set at 0.2-0.4 MPa and the condensation pressure at 0.9-2.5 MPa. The subcooling is determined by the difference between the temperature at the condenser outlet and the average temperature in the middle section, which is used in practical applications.

9. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step two, the system component capacity is calculated using the following formula: ； ； ； ； ； ； ； Mass flow rate in the air conditioning circuit; The actual selected heating and cooling loads; All represent enthalpy values; This is the total heat of reaction in the battery; K is a correction factor, with a value ranging from 1.05 to 1.15; V represents the compressor displacement; The volumetric efficiency of the compressor, with a value ranging from 0.7 to 0.9; N is the compressor speed, with a value ranging from 1000 to 4500. Represents refrigerant density; This refers to the compressor's compression power. Represents enthalpy value; This refers to the compressor shaft power. The mechanical efficiency of the compressor, with a value ranging from 0.7 to 0.8; , These are the heat loads of the condenser, evaporator, and chiller, respectively.

10. The method for selecting components of a thermal management system as described in claim 1, characterized in that: In step four, the analysis of component selection cases, dynamic evaluation of system flow distribution, temperature fluctuation and energy consumption performance, and verification of the robustness of the selection scheme during multi-mode thermal management coupling verification are all based on the thermal load of the cockpit, the thermal load of the battery, and the thermal load of the motor unit.

Images