Flow resistance and heat transfer simulation analysis method of thermal management refrigerant side integrated module

Abstract

The invention discloses a flow resistance and heat transfer simulation analysis method for a thermal management refrigerant side integrated module, and relates to the technical field of computer simulation. The method mainly comprises the following steps of: dividing a computational domain model into a solid domain, a fluid domain comprising a plurality of single-phase flow channel sub-domains and a flow channel section which is in a gas-liquid two-phase state and exchanges latent heat along with phase change in combination with the need of an actual analysis working condition; performing polynomial fitting on various parameters by fixing the inlet pressure value of each single-phase flow channel sub-domain; loading the fitted physical property function to the corresponding runner sub-domain, and setting a constant material attribute for the solid domain runner plate; a conjugate heat transfer model is started on an interface of a fluid domain and a solid domain, and interface heat flux density conservation and temperature continuity simulation is carried out; setting boundary conditions; and executing conjugate heat transfer simulation calculation until convergence calculation is completed. According to the method, the simulation precision is improved through fusion of three core technologies of dynamic change physical property fitting, solid-liquid conjugate heat transfer coupling and two-phase flow latent heat equivalent modeling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computer simulation, and particularly relates to a flow resistance and heat transfer simulation analysis method of a heat management refrigerant side integrated module. BACKGROUND

[0002] With the development of new energy vehicle thermal management system towards high integration, the refrigerant side integrated module is widely used due to its compact structure and efficient assembly. However, the traditional simulation analysis method has significant defects in simulating the flow resistance and heat transfer performance of such modules:

[0003] Firstly, the simplification of refrigerant physical property parameters is seriously distorted. The existing method usually sets the density, specific heat capacity, viscosity and other physical parameters of the refrigerant as fixed values, without fully considering their dynamic change characteristics with temperature and pressure under complex working conditions. This simplification leads to calculation deviation of the thermodynamic state in the single-phase flow channel, especially in the adjacent area of high and low temperature flow channels, which cannot accurately predict the heat loss caused by the nonlinear change of physical properties (such as invalid heat exchange caused by aluminum alloy flow channel plate heat conduction).

[0004] Secondly, the solid-liquid coupled heat transfer mechanism is not modeled completely. The traditional simulation does not establish the conjugate heat transfer coupling between the fluid domain (refrigerant) and the solid domain (flow channel plate), but only uses one-way thermal boundary conditions for approximation. This leads to two problems: one is the distortion of the temperature field distribution in the flow channel plate, which makes it difficult to quantify the heat conduction loss between high and low temperature flow channels; the other is the neglect of the reverse influence of wall temperature on the state of refrigerant, such as the heating of low temperature refrigerant by high temperature flow channel through the wall, which aggravates the energy loss.

[0005] Thirdly, the latent heat exchange of two-phase flow section is simplified incorrectly. For the gas-liquid two-phase flow section from the outlet of electronic expansion valve (EXV) to the inlet of evaporator, the existing method equivalent to single-phase flow only considers sensible heat exchange and completely ignores the phase change latent heat effect. This simplification is seriously deviated from the physical reality: the refrigerant needs to absorb a large amount of latent heat during evaporation and maintain the saturation temperature, while the traditional model cannot reflect the real heat transfer process in the phase change region due to the absence of constant temperature boundary condition, resulting in a calculation error of heat exchange efficiency of up to 20%~30%.

[0006] In addition, the environmental heat exchange boundary condition setting is rough. The automobile front compartment flow field has strong non-uniformity (high speed area and low speed vortex area coexist), but the existing method uses a single average heat transfer coefficient for the outer wall of the flow channel plate, without zoning and differential setting according to the air flow distribution. This leads to distortion of the calculation of environmental heat loss, and cannot provide effective basis for module layout optimization. SUMMARY

[0007] In order to solve the defects of traditional simulation analysis method in simulating the flow resistance and heat transfer performance of the module, the application provides a flow resistance and heat transfer simulation analysis method of a heat management refrigerant side integrated module, comprising the steps of: S1: constructing a calculation domain model of the refrigerant side integrated module, and combining the needs of actual analysis working conditions to divide into a solid domain, a fluid domain containing a plurality of single-phase flow channel subdomains, and a flow channel segment in a gas-liquid two-phase state and accompanied by latent heat exchange of phase change; S2: generating refrigerant property parameters at discrete temperature points based on a property database by fixing the inlet pressure value of each single-phase flow channel subdomain, and performing polynomial fitting on density, specific heat capacity, thermal conductivity and viscosity; S3: loading the fitted property function to the corresponding single-phase flow channel subdomain, and setting constant material properties for the flow channel plate of the solid domain; S4: enabling a conjugate heat transfer model at the interface between the fluid domain and the solid domain to simulate the heat flux conservation and temperature continuity of the interface; S5: setting mass flow inlet and free outflow outlet boundary conditions for the single-phase flow channel subdomain; S6: determining the saturation temperature based on the refrigerant pressure at the inlet of the gas-liquid two-phase flow channel segment, and setting the wall surface of the flow channel plate cavity corresponding to the flow segment as a constant temperature boundary condition of the saturation temperature; S7: setting a convective heat transfer boundary condition for the outer wall surface of the flow channel plate; S8: performing conjugate heat transfer simulation calculation until the calculation is completed, and extracting the pressure drop and outlet temperature of each single-phase flow channel subdomain of the fluid domain, the temperature field distribution of the solid domain, the pressure loss of the flow channel segment, and the heat loss data.

[0008] In general, the application significantly improves the simulation accuracy and engineering applicability by innovatively integrating three core technologies of dynamic variable property fitting, solid-liquid conjugate heat transfer coupling and two-phase flow latent heat equivalent modeling.

[0009] Further, in the S2 step, the discrete temperature points are dynamically determined based on the thermodynamic state of the flow channel, specifically: Taking the inlet temperature of the corresponding single-phase flow channel subdomain as the reference, the ±ΔT interval is extended according to the temperature gradient of the adjacent flow channel, and the upper and lower limits of the temperature need to ensure that the refrigerant state of the single-phase flow channel subdomain will not change phase, and ΔT is a preset temperature difference.

[0010] Further, in the S4 step, in the conjugate heat transfer model, when the fluid domain and the solid domain interface grid are not conformal, a gradient-preserving non-matching grid mapping algorithm is used to transfer the heat flux.

[0011] Further, in the S6 step, the setting position of the constant temperature boundary condition needs to meet: covering the wall surface of the flow channel plate cavity corresponding to the flow segment.

[0012] Further, in the S8 step, the heat loss data includes conjugate heat transfer loss at the interface between the fluid domain and the solid domain, latent heat loss of the phase change in the gas-liquid two-phase flow section, and convective heat transfer loss of the outer wall of the flow channel plate.

[0013] Further, the conjugate heat transfer loss is used to quantify the convective-thermal coupling energy transfer between the refrigerant and the flow channel plate, and is obtained by extracting the heat flux of each grid element at the interface and area integration along the interface.

[0014] Further, the heat loss of the gas-liquid two-phase flow section is used to reflect the invalid heat exchange conducted between the high-temperature flow channel and the low-temperature flow channel through the flow channel plate, and the normal temperature gradient of the wall surface is calculated according to the Fourier law, and the local heat flux density is obtained by combining the thermal conductivity of the material, and then the latent heat loss of the phase change is obtained by integrating the constant temperature boundary region.

[0015] Further, the heat loss of the outer wall of the flow channel plate is used to characterize the heat exchange amount between the integrated module and the front compartment environment of the automobile, and each partition heat loss is calculated according to the partition wall area and the corresponding heat transfer coefficient, combined with the wall temperature and the environment temperature, and the sum of each partition heat loss is the convective heat transfer loss.

[0016] Further, the partition is divided into several sub-regions according to the non-uniformity of the external environment physical field distribution, and boundary condition parameters are independently set for each sub-region.

[0017] Compared with the prior art, the present application has at least the following beneficial effects: (1) The flow resistance and heat transfer simulation analysis method of the heat management refrigerant side integrated module provided by the present application significantly improves the simulation accuracy and engineering applicability by innovatively integrating the three core technologies of dynamic variable property fitting, solid-liquid conjugate heat transfer coupling and two-phase flow latent heat equivalent modeling; (2) At the level of property processing, based on the variable property polynomial function generated by fixing the inlet pressure of the single-phase flow channel, the nonlinear change of the properties of the refrigerant under complex temperature and pressure conditions is accurately captured, and the thermodynamic state prediction error of the single-phase flow channel is greatly reduced compared with the traditional method, especially in the adjacent area of the high-temperature flow channel and the low-temperature flow channel, the heat loss calculation accuracy is significantly improved, and reliable basis is provided for the heat insulation design of the flow channel plate; (3) At the level of energy transfer mechanism, through the conjugate heat transfer model that satisfies the heat flux conservation and temperature continuity at the interface between the forced fluid domain and the solid domain, the bidirectional thermal coupling between the refrigerant and the aluminum alloy flow channel plate is completely restored, the simulation consistency of the temperature field distribution inside the flow channel plate is close to unity, and the quantization error of the invalid heat conduction loss between the high-temperature flow channel and the low-temperature flow channel is close; (4) For the treatment of two-phase flow section, the saturated temperature constant boundary condition is innovatively used to replace the traditional single-phase flow simplified model, and the latent heat exchange of phase change is simulated by the pressure-saturated temperature mapping relationship, which successfully compresses the calculation deviation of heat exchange efficiency in the gas-liquid two-phase zone. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A flow resistance and heat transfer simulation analysis method for a heat management refrigerant side integrated module; Figure 2 A computational domain model schematic diagram; Figure 3 A single-fluid domain model schematic diagram of this example; Figure 4 A single solid domain model schematic diagram of this example; Figure 5 A flow channel cavity wall surface schematic diagram of the EXV outlet→evaporator inlet section. DETAILED DESCRIPTION

[0019] The following is a specific embodiment of the present application and further describes the technical solutions of the present application in conjunction with the drawings, but the present application is not limited to these embodiments.

[0020] The current simulation analysis method for the refrigerant side integrated module applied to the heat management system generally has problems such as imperfect multi-dimensional physical field coupling modeling and insufficient energy loss quantization precision. In the traditional technology, for the fluid-structure coupling heat transfer analysis between the flow channel plate and the refrigerant, a one-way decoupling model or a simplified boundary condition is often used, and the influence of the dynamic balance of the heat flux density on the temperature field distribution in the fluid phase change process is ignored, which leads to a significant deviation between the simulation results of the internal heat conduction path of the flow channel plate and the actual working conditions. Especially in the high and low temperature flow channel adjacent layout scene, the existing method is difficult to accurately capture the gradient change rule of the invalid heat conduction between the flow channels, which makes the heat insulation structure design of the flow channel lack reliable thermodynamic basis. In addition, in the face of the complex phase change process of the refrigerant gas-liquid two-phase zone, the conventional single-phase flow simplified model cannot characterize the nonlinear characteristics of the latent heat exchange of phase change, and this over-simplification directly leads to a systematic deviation between the calculated heat exchange efficiency and the actual test data, which further affects the accuracy of the overall energy efficiency evaluation of the module. The above technical bottlenecks seriously restrict the iterative optimization efficiency of the high-energy efficiency heat management system, and a more accurate flow resistance and heat transfer simulation solution is urgently needed. Figure 1 As shown in the figure, the present application proposes a flow resistance and heat transfer simulation analysis method for a heat management refrigerant side integrated module, including the steps of:

[0021] S1: Construct a computational domain model of the refrigerant side integrated module, and divide it into a solid domain, a fluid domain containing several single-phase flow channel sub-domains, and a flow channel section in a gas-liquid two-phase state accompanied by latent heat exchange of phase change according to the needs of the actual analysis working condition; S2: Generate refrigerant property parameters at discrete temperature points based on property database by fixing the inlet pressure value of each single-phase flow passage subdomain, and perform polynomial fitting on density, specific heat capacity, thermal conductivity, and viscosity; S3: Load the fitted property functions to the corresponding single-phase flow passage subdomain, and set constant material properties for the solid domain flow passage plate; S4: Perform simulation of interfacial heat flux conservation and temperature continuity by enabling the conjugate heat transfer model at the interface between the fluid domain and the solid domain; S5: Set the mass flow inlet and free outflow outlet boundary conditions for the single-phase flow passage subdomain; S6: Determine the saturation temperature based on the refrigerant pressure at the inlet of the gas-liquid two-phase flow passage section, and set the wall surface of the flow passage plate cavity corresponding to the section as a constant temperature boundary condition at the saturation temperature; S7: Set the convective heat transfer boundary condition for the outer wall surface of the flow passage plate; S8: After the conjugate heat transfer simulation calculation is completed, extract the pressure drop and outlet temperature of each single-phase flow passage subdomain in the fluid domain, the temperature field distribution of the solid domain, the pressure loss of the flow passage section, and the heat transfer loss data.

[0022] Specifically, the S1 step needs to collect the structural information of the thermal management refrigerant side integrated module when building the computational domain model of the refrigerant side integrated module. In an example, the precise geometric shapes, size parameters, and layout methods of components such as electronic expansion valves (EXV), solenoid shut-off valves (SOV), check valves (CV), refrigerant PT sensors, battery coolers (Chiller), liquid-cooled condensers (LCC), and air conditioning pipeline interfaces on the refrigerant side flow passage plate are summarized, and the complex operating characteristics of the thermal management system under actual analysis conditions are closely combined. For example, in automotive thermal management applications, the refrigerant flow passage often contains typical scenarios of high and low temperature region interaction layout, in which certain flow passage sections are in stable single-phase flow state, while other flow passage sections frequently undergo gas-liquid two-phase transition accompanied by significant latent heat exchange phenomena. As shown in Table 1, the flow passage and flow passage inlet related information table, Figure 2 The computational domain model schematic diagram for this example is shown in

[0023] Table 1: Flow passage and flow passage inlet related information table To accurately reflect these physical processes, the computational domain model is carefully divided into three core parts (as Figure 3 The single fluid domain model schematic diagram for this example is shown in Figure 4 The single solid domain model schematic diagram for this example is shown in Figure 5As shown in FIG. 1, the simulation model of the refrigerant side integrated module is divided into three parts: solid domain, fluid domain and two-phase domain. The solid domain corresponds to the overall structure of the flow channel plate to simulate its heat conduction and support function. The fluid domain is further divided into multiple single-phase flow channel subdomains to independently process the refrigerant flow and heat exchange behavior in each single-phase region. Meanwhile, the two-phase domain is specially defined to capture the dynamic thermodynamic interaction during the phase change process. This division is based on the limitations of traditional simulation methods when dealing with multi-state flow channels. For example, when high and low temperature flow channels coexist, the existing model ignores the details of the internal heat conduction path of the flow channel plate, resulting in inaccurate quantification of invalid heat loss and inability to effectively simulate the influence of phase change latent heat in the two-phase region on the overall heat balance, thereby affecting the reliability of the module thermal efficiency and flow resistance analysis.

[0024] In the current simulation technology of the refrigerant side integrated module, the existing methods generally ignore the fine processing of the dynamic changes of the physical property parameters with temperature, especially in the single-phase flow channel subdomain. The thermophysical properties of the refrigerant (such as density, specific heat capacity, thermal conductivity and viscosity) are often simplified as constants or interpolated based on fixed temperature points, resulting in the inability to capture the property mutation phenomenon in the thermal gradient environment of adjacent high and low temperature flow channels, thereby introducing significant simulation errors. For example, ignoring the influence of temperature interval expansion on the continuity of physical properties will amplify the uncertainty of heat transfer and pressure drop calculation in the flow channel, affecting the reliability of energy efficiency optimization of the overall module.

[0025] To address this technical bottleneck, in S2, the inlet pressure value of each single-phase flow channel subdomain is fixed to lock the thermodynamic reference state of the refrigerant, and then the refrigerant property parameters at discrete temperature points are dynamically generated based on the property database (as shown in Table 2). The selection of discrete temperature points takes the inlet temperature of the corresponding subdomain as the initial reference point, and expands the interval of ±ΔT (preset temperature difference) based on the measured or simulated temperature gradient between adjacent flow channels, while strictly controlling the upper and lower limits of temperature to ensure that the refrigerant is always in a stable single-phase state within the selected interval, avoiding the problem of discontinuity of physical properties caused by potential phase change. Finally, the generated density, specific heat capacity, thermal conductivity and viscosity data are fitted with high-order polynomials to construct a smooth and physically reasonable property function model, thereby providing high-precision and differentiable property input basis for subsequent simulation calculation of the flow channel subdomain, overcoming the systematic bias caused by the simplification of physical properties in the traditional method under the thermal gradient environment.

[0026] Table 2: Refrigerant property parameters at discrete temperature points The discrete data points of each property parameter (ρ, cp, k, μ) are fitted with polynomials in Excel to ensure that the fitting accuracy meets (R²>0.99), and the expression is obtained, for example: ,​ , , .

[0027] The fixed inlet pressure value of each single-phase flow channel subdomain is adopted here because in the steady-state operating condition analysis of the refrigerant-side integrated module, the system pressure distribution is maintained relatively stable by the coordinated adjustment of key components such as the compressor and the expansion valve, and temperature variation becomes the dominant variable affecting the dynamic evolution of the physical property parameters. For a single-phase flow channel subdomain (such as the compressor discharge port→liquid-cooled condenser (LCC) inlet flow channel), the refrigerant is always in a stable single-phase state (gas or liquid), and the pressure fluctuation amplitude is much smaller than the temperature variation range - taking the gaseous flow channel as an example, the compressor outlet pressure fluctuation is usually controlled within ±0.5 bar, and the fluctuation rate is less than 2.5% compared with the absolute pressure value of 20 bar. The influence of such small pressure variation on the physical property parameters can be ignored: according to the thermodynamic state equation, the sensitivity of the density and viscosity of single-phase refrigerant to pressure variation is significantly lower than that to temperature. For example, at a pressure reference of 20 bar, the density variation amplitude of gaseous refrigerant caused by a temperature rise of 1 °C can reach 0.15%, while under the same conditions, the density deviation caused by a pressure fluctuation of ±0.5 bar is less than 0.02%.

[0028] Therefore, by fixing the inlet pressure value as the typical operating pressure, both the physical fact of relatively constant pressure in actual engineering and the focus of calculation resources on temperature-dominated physical property nonlinear modeling are met, effectively avoiding the problem of explosive calculation complexity caused by double-variable coupling, while ensuring controllable polynomial fitting errors.

[0029] And with the aid of the temperature-dependent physical property polynomial function generated in the aforementioned S2 step, the engineering defects of traditional physical property loading methods need to be addressed when implementing the S3 step: the traditional method uses piecewise linear interpolation or discrete point table lookup to load physical property parameters, and when there is a steep temperature gradient between adjacent flow channels (such as a temperature jump of ), the non-continuity of discrete point sampling will cause numerical oscillation problems, leading to simulation calculation divergence or slow convergence. Therefore, the S3 step directly embeds the fitted high-order continuous derivable physical property function (such as a fourth-order polynomial) into the physical property definition interface of the computational fluid dynamics (CFD) software, so that each single-phase flow channel subdomain has the ability to dynamically update the physical properties adaptively to temperature - for example, in a condenser outlet liquid flow channel (inlet pressure P1=18 bar, corresponding to an inlet temperature ) in an example, when the refrigerant flows through the adjacent area of the high-temperature bypass flow channel, its local temperature may rise to 65 °C, at which point the continuous independent variable output of the physical property function based on T accurately outputs the thermal conductivity While the traditional discrete interpolation method may be extrapolated incorrectly at 55-65℃ without sampling points , causing a local heat transfer coefficient calculation deviation of more than 6%.

[0030] At the same time, the thermal physical property settings of the solid domain flow channel plate (typically made of 6061 aluminum alloy) are simplified to constant values (thermal conductivity , specific heat capacity ). This is because the fluctuation rate of the thermal conductivity of aluminum alloy is less than 2% in the temperature range of -40℃ to 150℃, which is much lower than the sensitivity of the refrigerant properties to temperature (for example, the viscosity of liquid refrigerant changes by up to 300% in the temperature range of 0-80℃). This simplification significantly reduces the complexity of solid domain calculation while ensuring accuracy.

[0031] After establishing high-precision dynamic property functions and constant property settings for the solid domain, the fundamental defect of the traditional method in the treatment of the fluid-solid interface is addressed: the existing one-way heat transfer model (such as only using the solid temperature as the boundary condition of the fluid domain) cannot reflect the bidirectional energy exchange between the refrigerant and the flow channel plate, leading to distortion in the prediction of the temperature field in the high-low temperature flow channel interface area. For example, when high-temperature gaseous refrigerant (85℃ inlet) flows through the adjacent area of the low-temperature liquid cooling flow channel (15℃ inlet), a transverse heat conduction path is formed inside the flow channel plate. The traditional one-way model ignores the reverse influence of fluid convection heat transfer on the solid temperature distribution, resulting in a large deviation in the predicted temperature difference in this area compared to the actual measured value.

[0032] Therefore, in step S4, the present application enables a conjugate heat transfer model at the interface between the fluid domain and the solid domain, and enforces the bidirectional coupling constraints of heat flux conservation ( ) and temperature continuity ( ). It is particularly critical that when the grid independence requirement in actual engineering leads to non-conformal grids at the interface between the fluid domain and the solid domain (such as 0.2mm boundary layer grid for the fluid domain and 1mm hexahedral grid for the solid domain), a gradient-preserving non-matching grid mapping algorithm is used to transfer the heat flux: based on the Galerkin method, the heat flux interpolation on the fine grid side (fluid domain) is projected to the coarse grid side (solid domain), and a first-order gradient correction term is introduced to compensate for the discretization error. Compared with the traditional surface weighted average method, the interface heat flux transfer deviation is significantly reduced in the test case of the inclined surface interface area of the flow channel plate of the vapor-liquid separator, effectively eliminating the false thermal resistance phenomenon caused by non-conformal grids.

[0033] It is well known that the accurate construction of the model is one aspect in the simulation process, and the reasonableness of the boundary condition setting directly determines the physical reality of the coupled solution of the flow field and the temperature field. For the inlet boundary of the single-phase flow channel subdomain, the core technical consideration of using mass flow rate inlet instead of traditional pressure inlet in S5 step lies in that, in the actual operation of the refrigerant side integrated module, the upstream components such as the compressor and the electronic expansion valve maintain the system refrigerant mass flow rate constant (typical value ) through closed-loop control, and the pressure value dynamically fluctuates with the working condition. If the pressure inlet boundary is incorrectly used, the heat interaction between the adjacent high-temperature flow channel (such as the compressor discharge channel) and the low-temperature flow channel (such as the condenser outlet section) will lead to inaccurate flow distribution of each flow channel subdomain - the simulation case shows that when the compressor discharge channel (gaseous single-phase zone) is incorrectly set as 0.5 MPa pressure inlet, the mass flow rate prediction value is 12.3% higher than the actual value due to the local flow resistance change caused by ignoring the low-temperature flow channel heat return.

[0034] At the same time, the outlet boundary is set as free outflow (zero gradient special case of pressure outlet), and its necessity is derived from the special processing requirement of the two-phase flow channel section: since the saturation temperature boundary will be applied to the gas-liquid two-phase flow section in the subsequent S6 step, if a fixed pressure boundary (such as 0.3 MPa) is imposed at the outlet of the adjacent single-phase flow channel subdomain, the pressure continuity between the phase change section and the single-phase section will be artificially broken, and the natural distribution of the overall temperature field of the flow channel plate will be destroyed. For example, in the single-phase liquid flow channel upstream of the evaporator inlet two-phase section, the free outlet boundary allows the outlet pressure to adaptively match the inlet pressure of the downstream two-phase section (actual fluctuation range ±7 kPa), thereby avoiding the false backflow phenomenon caused by pressure sudden change and ensuring the quantitative accuracy of the invalid heat conduction between the flow channels.

[0035] After the mass flow rate inlet and the free outflow outlet boundary conditions of the single-phase flow channel subdomain are set in S5 step, the entire simulation framework needs to further solve the special thermodynamic challenge of the gas-liquid two-phase flow section: the traditional method often simplifies the two-phase zone as an isothermal boundary or ignores the phase change latent heat effect, leading to distorted prediction of the invalid heat conduction of the flow channel plate, especially in the high and low temperature flow channel interaction scene of automobile thermal management, the inaccurate temperature gradient model of the phase change zone will systematically amplify the calculation error of heat exchange loss. Therefore, S6 step first determines the corresponding saturation temperature (such as evaporator inlet saturation temperature ) based on the refrigerant pressure at the inlet of the gas-liquid two-phase flow section (such as evaporator inlet pressure ), which directly reflects the thermodynamic basis point of phase change.

[0036] Subsequently, to ensure the physical reality of the boundary conditions, the wall surface of the flow channel plate cavity corresponding to the flow section (i.e. the structural interface directly wrapping the two-phase flow channel) is set as a constant temperature boundary condition of the saturation temperature, and the setting position must strictly cover the entire wall surface area affected by the flow section - for example, in the flow section from the condenser outlet to the evaporator inlet, if the cavity wall surface coverage is insufficient (such as only setting a local area), a false temperature jump will occur due to uneven heat flux density distribution, resulting in a large deviation of the latent heat loss in the subsequent calculation. This constant temperature boundary setting not only forces the saturation state in the two-phase flow section, simulates the latent heat absorption or release dynamics during the phase change of the refrigerant, and provides a temperature field basis for the subsequent quantification of the invalid heat exchange in step S8.

[0037] In addition, after completing the saturation temperature boundary setting inside the gas-liquid two-phase flow section, the heat exchange modeling problem between the flow channel plate and the external environment also needs to be further solved. The traditional method often simplifies the outer wall surface of the flow channel plate as an adiabatic boundary or a fixed temperature boundary, ignoring its dynamic convective heat transfer characteristics in the actual engineering environment - for example, in the electric vehicle thermal management module, the outer wall surface of the flow channel plate may be exposed to high-speed airflow (forced convection) or static air (natural convection) environment in the engine compartment. If the adiabatic assumption is incorrectly used (such as setting the heat flux ), the internal heat accumulation effect of the flow channel plate will be severely underestimated: the measured data shows that at a vehicle speed of , the outer wall surface of the flow channel plate near the motor heat source area is overestimated by 22.3°C compared to the measured value due to the neglect of forced convection cooling, which in turn distorts the internal refrigerant temperature field distribution.

[0038] Therefore, step S7 sets the convective heat exchange boundary condition for the outer wall surface of the flow channel plate to accurately characterize the complex thermal interaction between the external environment and the module. In specific implementation, the outer wall surface is divided into several heat exchange regions (such as the windward surface, the leeward surface, and the near heat source surface) according to the actual on-board environment, and different convective heat transfer coefficients (h values) are assigned based on the Reynolds similarity criterion: the windward surface adopts a high value (typical range ) due to the impact of high-speed airflow, and the leeward surface takes a low value (typical range ) according to the wake separation characteristics. This refined setting makes the internal heat conduction path simulation of the flow channel plate more realistic, providing a reliable boundary condition basis for the optimization of the thermal insulation structure.

[0039] Finally, after completing the boundary condition setting of the coupled flow and temperature field system, the conjugate heat transfer simulation calculation is performed until the residual converges, and the physical field data extracted at this time needs to be systematically revealed to indicate the comprehensive performance of the thermal management module.

[0040] Firstly, based on the pressure drop data (such as the liquid flow channel of the evaporator inlet ) and the outlet temperature distribution of each single-phase flow channel sub-domain, the refrigerant flow resistance and sensible heat exchange efficiency can be evaluated; at the same time, the temperature field distribution of the solid domain (such as the maximum temperature difference between the high-temperature and low-temperature flow channels ) intuitively reflects the spatial characteristics of the invalid heat conduction, providing a direction for the optimization of the heat insulation structure. For the pressure loss of the gas-liquid two-phase flow section, the numerical source is the flow state mutation effect caused by phase change (such as the sharp increase in local pressure drop caused by bubble growth), and the reliability of the phase change model needs to be verified by combining the application accuracy of the saturation temperature boundary condition.

[0041] Especially critical is the fine analysis of heat loss data: with the help of the heat flux field generated by the S4 step non-matching grid mapping algorithm, the heat flux density area integral is performed on the interface between the fluid domain and the solid domain, and the conjugate heat transfer loss ( ) is obtained, which reflects the two-way energy coupling between the refrigerant and the flow channel plate; for the invalid heat exchange between the high-temperature and low-temperature flow channels, according to the temperature gradient distribution of the constant temperature boundary region in S6 step, the latent heat loss of phase change ( ) is calculated by Fourier law integral; at the same time, based on the partition parameters of the outer wall surface (such as the windward surface and the leeward surface) and the measured wall surface temperature in S7 step, the convective heat loss ( ) is obtained by weighted summation. The sum of the above quantitative data ( ) significantly improves the full-dimensional accuracy of the thermal management module energy efficiency analysis compared with the traditional single heat loss model, providing reliable engineering decision basis for system optimization.

[0042] In summary, the flow resistance and heat transfer simulation analysis method of the thermal management refrigerant side integrated module proposed in the present application significantly improves the simulation accuracy and engineering applicability by innovatively integrating the three core technologies of dynamic variable property fitting, solid-liquid conjugate heat transfer coupling and two-phase flow latent heat equivalent modeling.

[0043] At the level of property processing, based on the variable property polynomial function generated by fixing the inlet pressure of the single-phase flow channel, the nonlinear change of the properties of the refrigerant under complex temperature and pressure conditions is accurately captured, and the prediction error of the thermodynamic state of the single-phase flow channel is significantly reduced compared with the traditional method, especially in the high-temperature and low-temperature flow channel adjacent area, the heat loss calculation accuracy is significantly improved, providing reliable basis for the heat insulation design of the flow channel plate; At the level of energy transfer mechanism, through the conjugate heat transfer model that satisfies the heat flux density conservation and temperature continuity at the interface between the fluid domain and the solid domain, the two-way thermal coupling between the refrigerant and the aluminum alloy flow channel plate is completely restored, the simulation consistency of the internal temperature field distribution of the flow channel plate is close to one, and the quantitative error of the invalid heat conduction loss between the high-temperature and low-temperature flow channels is close.

[0044] For the treatment of two-phase flow section, the saturated temperature constant boundary condition is innovatively used to replace the traditional single-phase flow simplified model, the latent heat exchange is simulated by pressure-saturated temperature mapping relationship, and the heat exchange efficiency calculation deviation of the gas-liquid two-phase region is successfully compressed.

[0045] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directional indications will also change accordingly.

[0046] In addition, the descriptions such as "first", "second", "one" and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0047] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] In addition, the technical solutions of each embodiment of the present application can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the scope of protection required by the present application.

Claims

1. A simulation analysis method for flow resistance and heat transfer of a thermal management refrigerant-side integrated module, characterized in that, Including the following steps: S1: Construct a computational domain model for the refrigerant-side integrated module, and divide it into a solid domain, a fluid domain containing several single-phase flow channel subdomains, and a flow channel segment in a gas-liquid two-phase state accompanied by latent heat exchange of phase change, based on the needs of actual analysis conditions. S2: By fixing the inlet pressure value of each single-phase flow channel subdomain, the refrigerant property parameters at discrete temperature points are generated based on the property database, and polynomial fitting is performed on density, specific heat capacity, thermal conductivity and viscosity. S3: Load the fitted physical property function into the corresponding single-phase flow channel subdomain and set constant material properties for the solid domain flow channel plate; S4: Simulation of interface heat flux density conservation and temperature continuity is performed by enabling the conjugate heat transfer model at the interface between the fluid and solid domains. S5: Set mass flow rate inlet and free outlet boundary conditions for the single-phase flow channel subdomain; S6: Determine the saturation temperature based on the refrigerant pressure at the inlet of the gas-liquid two-phase flow channel section, and set the flow channel plate cavity wall corresponding to the flow channel section as the isothermal boundary condition of the saturation temperature. S7: Set the convective heat transfer boundary conditions on the outer wall of the flow channel plate; S8: Perform conjugate heat transfer simulation calculations until convergence is complete, then extract the pressure drop and outlet temperature of each single-phase flow channel subdomain in the fluid domain, the temperature field distribution in the solid domain, the pressure loss in the flow channel section, and the heat transfer loss data.

2. The simulation analysis method for flow resistance and heat transfer of a thermal management refrigerant-side integrated module as described in claim 1, characterized in that, In step S2, the discrete temperature points are dynamically determined by the thermodynamic state of the flow channel, specifically as follows: Based on the inlet temperature of the corresponding single-phase flow channel subdomain, the ±ΔT range is expanded according to the temperature gradient of adjacent flow channels. At the same time, the upper and lower limits of the temperature must ensure that the refrigerant state of the single-phase flow channel subdomain does not undergo a phase change. ΔT is a preset temperature difference value.

3. The method for simulation analysis of flow resistance and heat transfer of a thermal management refrigerant-side integrated module as described in claim 1, characterized in that, In step S4, in the conjugate heat transfer model, when the mesh at the interface between the fluid domain and the solid domain is non-conformal, a gradient-preserving non-matching mesh mapping algorithm is used to transfer the heat flux density.

4. The method for simulation analysis of flow resistance and heat transfer of a thermal management refrigerant-side integrated module as described in claim 1, characterized in that, In step S6, the location of the constant temperature boundary condition must satisfy the following condition: cover the wall surface of the flow channel plate cavity corresponding to the flow channel section.

5. The simulation analysis method for flow resistance and heat transfer of a thermal management refrigerant-side integrated module as described in claim 1, characterized in that, In step S8, the heat transfer loss data includes conjugate heat transfer loss at the interface between the fluid domain and the solid domain, latent heat loss due to phase change in the gas-liquid two-phase flow section, and convective heat transfer loss on the outer wall of the flow channel plate.

6. The method for simulation analysis of flow resistance and heat transfer of a thermal management refrigerant-side integrated module as described in claim 5, characterized in that, The conjugate heat transfer loss is used to quantify the convective-conductive energy transfer between the refrigerant and the flow channel plate. It is obtained by extracting the heat flux of each grid cell at the interface and integrating it along the interface.

7. The method for simulation analysis of flow resistance and heat transfer of a thermal management refrigerant-side integrated module as described in claim 5, characterized in that, The heat loss of the gas-liquid two-phase flow section is used to reflect the ineffective heat exchange conducted through the flow channel plate between the high and low temperature flow channels. The normal temperature gradient of the wall is calculated according to Fourier's law, and the local heat flux density is obtained by combining the thermal conductivity of the material. The latent heat loss of phase change is obtained by integrating over the isothermal boundary region.

8. The method for simulation analysis of flow resistance and heat transfer of a thermal management refrigerant-side integrated module as described in claim 5, characterized in that, The heat loss of the outer wall of the flow channel plate is used to characterize the heat exchange between the integrated module and the car's front compartment environment. The heat loss of each zone is calculated based on the zone wall area and the corresponding heat transfer coefficient, combined with the wall temperature and the ambient temperature. The sum of the heat losses of each zone is the convective heat transfer loss.

9. The method for simulation analysis of flow resistance and heat transfer of a thermal management refrigerant-side integrated module as described in claim 8, characterized in that, The partitioning is based on the non-uniformity of the physical field distribution in the external environment, dividing the outer wall of the flow channel plate into several sub-regions, and setting boundary condition parameters independently for each sub-region.

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