Microchannel condenser flow distribution global simulation method and system

Abstract

The invention discloses a microchannel condenser flow distribution global simulation method and system, and relates to the field of microchannel condenser flow distribution calculation. The method comprises the following steps: firstly, constructing a heat transfer and resistance model and forming a single-channel model by combining the size and structure of a parallel channel of the condenser and working medium flow heat exchange characteristics, and constructing a shunting and converging numerical model according to an inlet and outlet area structure of the condenser; secondly, numerical simulation is conducted on the division and convergence numerical model, and stable initial field distribution is obtained; then, determining the mass flow rate of each channel based on the shunting initial field, calculating the back pressure of the channel by taking the mass flow rate as the inlet boundary condition of a confluence model, calculating the inlet pressure of the channel through a single-channel model, and updating the outlet boundary of the shunting model; and finally, iterating the process until the channel mass flow error is smaller than a limit value, obtaining the distribution of the sub-confluence three-dimensional physical field and the one-dimensional flow heat exchange parameters and the heat exchange amount of the parallel channels, and checking whether the heat exchange amount meets the design requirements or not. The method gives consideration to calculation efficiency and precision, can provide support for structure optimization of the micro-channel condenser, and is suitable for micro-channel condenser design in the fields of refrigeration equipment, air conditioning systems and the like.

Description

Technical Field

[0001] This invention relates to the field of global simulation calculation methods for flow distribution in microchannel condensers, specifically to a global simulation method and system for flow distribution in microchannel condensers. Background Technology

[0002] Microchannel condensers (hereinafter referred to as condensers) are devices that primarily utilize the condensation phase change process of a working fluid to achieve heat transfer between hot and cold fluids, meeting specific process requirements. They come in various forms and channel types and are widely used in refrigeration equipment, air conditioning systems, and many other fields. Due to their small channel dimensions and complex condensation phase change process, the flow distribution characteristics of condensers have a particularly significant impact on heat transfer performance. This can lead to problems such as uncertain working fluid outlet phase state, excessive pressure drop, and reduced heat transfer coefficient, significantly decreasing condenser efficiency. Therefore, how to improve the working fluid flow distribution characteristics within the condenser and enhance its overall efficiency has become a key focus for manufacturers and scholars in the industry.

[0003] Currently, academic research on the flow distribution characteristics of the working fluid within condensers generally employs three methods: experimental research, numerical calculation, and theoretical research. Experimental research, limited by measurement techniques, has limitations in observing and analyzing condensation phase change conditions. Computational fluid dynamics software can simulate the flow distribution of the condenser's inlet and outlet sub-junction structures at a detailed spatial scale; however, the flow distribution characteristics of these structures are not only related to the structural features of the region but also influenced by the heat transfer of the working fluid within the channels, especially when the condensation phase change process is involved, as the heat transfer process is complex. Furthermore, fully considering channel heat transfer results in a massive mesh size for simulation analysis, requiring enormous computational resources and time, making rapid analysis of condenser flow distribution characteristics difficult in engineering design. The accuracy of numerical simulations of channel heat transfer also depends on the accurate setting of the computational domain boundary conditions. When using theoretical models, the physical field information of the condenser's inlet and outlet sub-junction structures and channels is simplified to a one-dimensional distribution, failing to obtain three-dimensional physical field information for key regions of the sub-junction structures.

[0004] Furthermore, due to the limitations of computational fluid dynamics (CFD) software, a single-channel condenser model, i.e., a one-dimensional two-phase flow heat transfer calculation program, was developed for simulating heat transfer parameters of single-channel condensation phase change flow. The single-channel model divides the channel into multiple control volumes to simulate the working fluid flow process, calculating the friction flow heat transfer parameters of the working fluid through heat transfer and resistance models. To a certain extent, the single-channel model effectively simulates the flow heat transfer phenomena of complex condenser structures, and its computational efficiency is significantly improved compared to CFD software.

[0005] Therefore, although scholars have developed numerous methods for simulating the distribution of the working fluid and flow heat transfer phenomena inside condensers, a method that is both efficient and practical has yet to be developed that can comprehensively and accurately quantify the distribution of the working fluid within the condenser. One-dimensional theoretical models can analyze flow distribution but cannot obtain the physical field distribution at the inlet and outlet. Computational fluid dynamics methods can simulate the distribution of all physical fields in the entire condenser relatively well, but due to their excessive computational load, they cannot meet the computational requirements and are therefore only used for local simulations. Single-channel models can obtain flow heat transfer parameters during condensation phase change heat transfer within the channel, but their computational significance is limited in the absence of reliable inlet boundary condition parameters.

[0006] By interacting with information during computation and coupling simulations of different dimensions, the optimal estimate of flow heat transfer information within the parallel channels of the condenser can be obtained, along with detailed physical field information at the condenser inlet and outlet. If a greater concern is the change in the detailed physical field of the condenser inlet and outlet structure under transient conditions, the optimal estimated boundary conditions provided in real-time by the single-channel model are more accurate and convenient than manually input boundary conditions. If a greater concern is the flow distribution characteristics under steady-state conditions in the parallel channels, the detailed physical results at the inlet and outlet are obtained through computational fluid dynamics numerical simulation, and the flow distribution characteristics of the parallel channels are closer to reality. Therefore, the method proposed in this paper for coupling computational fluid dynamics software with a one-dimensional two-phase flow heat transfer calculation program has significant reference value and guiding significance for the development of global simulation methods for condenser flow distribution. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a global simulation method and system for flow distribution in microchannel condensers. This method combines the advantages of one-dimensional two-phase flow heat transfer calculation program with three-dimensional computational fluid dynamics simulation, greatly improving computational efficiency and obtaining the flow heat transfer parameters of condenser channels and the physical field distribution information at the flow distribution and merging structures.

[0008] This invention is achieved through the following technical solution: A global simulation method for flow distribution in a microchannel condenser includes the following steps: Step 1: Construct a heat transfer and resistance model based on the dimensions and structure of the parallel channels of the condenser and the heat transfer characteristics of the working fluid flow; and construct a single-channel model of the condenser based on the heat transfer and resistance model. Based on the structure of the inlet and outlet areas of the condenser, construct the flow splitting numerical model and the flow combining numerical model of the condenser. Step 2: Based on the shunt numerical model and the confluence numerical model, determine the stable initial field distribution of the shunt structure and the stable initial field distribution of the confluence structure, respectively. Step 3: Determine the mass flow rate of each channel based on the stable initial field distribution of the split structure, use the mass flow rate of each channel as the boundary condition of the inlet mass flow rate of each channel in the condenser numerical model, and perform simulation calculations on the condenser numerical model to obtain the back pressure of each channel of the condenser. Step 4: Input the back pressure and mass flow rate of each channel into the inlet boundary parameters of the condenser single-channel model, perform simulation calculations on the condenser single-channel model to determine the inlet pressure of each channel, and update the outlet pressure boundary conditions of the split numerical model according to the inlet pressure. Step 5: Repeat steps 2-4 for iterative calculations until the mass flow rate of each channel meets the requirements, and obtain the fluid dynamic parameters of the split numerical model and the confluence numerical model, as well as the working fluid flow and heat transfer parameters of the channels.

[0009] Preferably, the step of constructing a single-channel condenser model based on the heat transfer and resistance model includes: Based on the dimensions and structure of the parallel channels of the condenser, and using the length-segmentation method, different empirical correlations for flow heat transfer are used to construct heat transfer and resistance models of the working fluid in the condenser channels for different zones, thereby forming a single-channel condenser model. Preferably, the step of constructing the condenser's flow splitting numerical model and flow combining numerical model based on the condenser's inlet and outlet region structure includes: A three-dimensional geometric model of the flow splitting zone is constructed based on the structure of the condenser inlet region, and a three-dimensional geometric model of the flow convergence zone is constructed based on the structure of the condenser outlet region. Mesh the 3D geometric models of the shunt and the confluence to obtain the numerical models of the shunt and the confluence.

[0010] Preferably, the numerical simulation calculations of the shunting numerical model and the merging numerical model respectively include: The inlet boundary conditions of the splitting numerical model and the confluence numerical model are set as mass flow rate inlet and pressure outlet boundary conditions, and the inlet mass flow rate and outlet pressure of the splitting numerical model and the confluence numerical model are the same. The splitting numerical model and the confluence numerical model are numerically simulated using fluid dynamics software to obtain the corresponding stable initial field distribution.

[0011] Preferably, the inlet pressure of each channel is determined based on the back pressure and the pressure drop of the working medium along the flow path. The calculation method for the inlet pressure is as follows:

[0012] In the formula: P i,new Updated inlet pressure values ​​for each channel; Δ P i For the pressure drop along each channel; P i,backThis refers to the back pressure of each channel.

[0013] Preferably, the mass flow rate requirements for each channel are as follows: If the error of the mass flow rate of each channel obtained in two adjacent iterations is less than the limit value, the three-dimensional physical field distribution of the split numerical model and the confluence numerical model, as well as the flow heat transfer parameters and heat transfer of the working fluid in each channel are obtained.

[0014] Preferably, the fluid dynamics data and flow heat transfer parameters of the channel in the splitting numerical model and the confluence numerical model include: The fluid dynamics data is a three-dimensional physical field distribution; The flow heat transfer parameters include the flow heat transfer parameters and heat transfer capacity of the working fluid in each channel; Based on the three-dimensional physical field distribution of the split-flow numerical model and the confluence numerical model, the flow heat transfer parameters and heat transfer of the working fluid in each channel are used to verify whether the heat transfer of each parallel channel of the condenser meets the design requirements under the condition of uneven flow distribution.

[0015] A global simulation system for flow distribution in a microchannel condenser includes the following steps: The model building module is used to build heat transfer and resistance models based on the dimensions and structure of the parallel channels of the condenser and the heat transfer characteristics of the working fluid flow, and to build a single-channel model of the condenser based on the heat transfer and resistance models. Based on the structure of the inlet and outlet areas of the condenser, construct the flow splitting numerical model and the flow combining numerical model of the condenser. The simulation module is used to determine the stable initial field distribution of the shunt structure and the stable initial field distribution of the confluence structure based on the shunt numerical model and the confluence numerical model, respectively. The back pressure module is used to determine the mass flow rate of each channel based on the stable initial field distribution of the split structure. The mass flow rate of each channel is used as the boundary condition of the inlet mass flow rate of each channel in the condenser numerical model. The condenser numerical model is then simulated to obtain the back pressure of each channel of the condenser. The outlet pressure module is used to input the back pressure and mass flow rate of each channel into the inlet boundary parameters of the condenser single-channel model, perform simulation calculations on the condenser single-channel model to determine the inlet pressure of each channel, and update the outlet pressure boundary conditions of the split numerical model based on the inlet pressure. The iteration module is used to repeatedly execute the simulation module, back pressure module, and outlet pressure module until the mass flow rate of each channel meets the requirements, thereby obtaining the fluid dynamic parameters of the split numerical model and the confluence numerical model, as well as the working fluid flow and heat transfer parameters of the channel.

[0016] An electronic device, comprising: Memory, used to store computer programs; A processor is used to implement the steps of the global simulation method for microchannel condenser flow distribution when executing the computer program.

[0017] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the global simulation method for flow distribution of a microchannel condenser.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: This application provides a global simulation method for flow distribution in a microchannel condenser, which models the channels and the flow splitting and merging regions of the condenser separately. It uses a single-channel model to accurately describe the working fluid flow and heat transfer process, and uses the flow splitting and merging numerical models to restore the physical field of the flow splitting and merging regions. Then, iterative calculations are used to achieve parameter matching between the two. First, it resolves the efficiency-accuracy contradiction of existing technologies, avoiding the problems of large mesh size and high computational resource consumption in pure 3D simulation, and overcoming the deficiency of pure 1D simulation in obtaining 3D physical field information of the flow distribution region, thus balancing computational speed and result precision. Second, it realizes the closed-loop transfer of "flow distribution-channel" parameters, ensuring the continuity of the physical field and the consistency of parameters through iterative updating of boundary conditions, making the final fluid dynamic parameters and working fluid flow heat transfer parameters more consistent with actual working conditions. Third, it has engineering applicability, and after convergence, it can directly output the 3D physical field distribution of the flow distribution and the heat transfer of the channels, which can quickly verify whether the condenser meets the design requirements when the flow distribution is uneven, providing accurate data support for condenser structure optimization (such as adjusting the flow distribution structure and channel size), and is suitable for microchannel condenser design scenarios in multiple fields such as refrigeration equipment and air conditioning systems.

[0019] This application also proposes a microchannel condenser flow distribution system, an electronic device, and a computer storage medium, which possess all the advantages of a global simulation method for microchannel condenser flow distribution. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A simplified schematic diagram of the solid and fluid domains of a microchannel condenser provided in an embodiment of the present invention; Figure 2 This is a simplified schematic diagram of the microchannel condenser's flow distribution structure and channel calculation according to an embodiment of the present invention; Figure 3This is a flowchart of the global simulation method for flow distribution in a microchannel condenser according to the present invention; Figure 4 This is a diagram illustrating the sequence of cross-dimensional coupled simulation data calculation and transmission in this invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0024] A global simulation method for flow distribution in a microchannel condenser includes the following steps: Step 1: Construct a heat transfer and resistance model based on the dimensions and structure of the parallel channels of the condenser and the heat transfer characteristics of the working fluid flow; and construct a single-channel model of the condenser based on the heat transfer and resistance model. Based on the structure of the inlet and outlet areas of the condenser, construct the flow splitting numerical model and the flow combining numerical model of the condenser. For the single-channel condenser model, we first combine the actual size and structure of the parallel channels, as well as the heat transfer characteristics of the working fluid (such as the mass flow rate range, dryness range, etc.), to construct a heat transfer and resistance model that can reflect the heat transfer law and flow resistance changes in the channel. Then, we further refine the single-channel model based on this model. Its function is to accurately describe the flow and heat transfer process of the working fluid in a single channel, and to provide a basis for subsequent channel parameter calculations. The numerical models for splitting and merging are constructed based on the actual structure of the condenser inlet and outlet regions (such as the shape and size of the splitting and merging cavities). Their purpose is to restore the physical field environment of the splitting and merging regions, preparing for the subsequent acquisition of the fluid dynamic parameters (such as pressure and flow rate) of the splitting and merging regions. The combination of the two realizes the separation of the "one-dimensional calculation of the channel" and the "three-dimensional simulation of the splitting and merging", which ensures the accuracy of the calculation and avoids the waste of resources in the overall modeling.

[0025] Step 2: Perform numerical simulations on the shunt numerical model and the confluence numerical model respectively to obtain the stable initial field distribution of the shunt structure and the stable initial field distribution of the confluence structure; By applying appropriate boundary conditions (setting the inlet as a mass flow rate inlet and the outlet as a pressure outlet) to the constructed splitting and merging numerical models using computational fluid dynamics software (such as Fluent), numerical simulations are performed until the physical field parameters (such as pressure and velocity) no longer change significantly, resulting in a stable initial field distribution. This serves to provide initial data support for subsequent coupled iterations, preventing iteration divergence due to unreasonable initial values. Simultaneously, it provides preliminary information on the physical field characteristics of the splitting and merging regions, laying the foundation for determining the channel mass flow rate and conducting merging simulations, ensuring the orderly initiation of the entire coupled computation.

[0026] Step 3: Determine the mass flow rate of each channel based on the stable initial field distribution of the split structure, use the mass flow rate of each channel as the boundary condition of the inlet mass flow rate of each channel in the condenser numerical model, and perform simulation calculations on the condenser numerical model to obtain the back pressure of each channel of the condenser. The mass flow rate of each channel is extracted from the stable initial field of the splitting structure (this flow rate reflects the initial state of flow distribution from the splitting region to each channel). This mass flow rate is used as the inlet mass flow rate boundary condition for each channel in the confluence numerical model. Because the physical field of the confluence region is affected by the inflow of each channel, it needs to be calculated based on the actual splitting results. Then, the back pressure of each channel (i.e., the reverse pressure of the confluence end on the channel) is obtained through confluence model simulation. Its purpose is to establish the correlation between the splitting and confluence models, and at the same time obtain the pressure influence parameters of the confluence end on the channel, providing key data for subsequent calculation of channel inlet pressure and updating of the splitting model boundary conditions.

[0027] Step 4: Input the back pressure and mass flow rate of each channel into the inlet boundary parameters of the condenser single-channel model, perform simulation calculations on the condenser single-channel model, obtain the pressure drop along the working fluid in each channel, determine the inlet pressure of each channel based on the back pressure and the pressure drop along the working fluid in each channel, and update the outlet pressure boundary conditions of the split numerical model based on the inlet pressure. Using the single-channel model constructed in step 1, the mass flow rate (reflecting the inflow rate) and back pressure (reflecting the outflow pressure) of each channel obtained in step 3 are input to simulate and calculate the friction drop (i.e., the pressure loss of the working medium flowing in the channel) during the working medium flow process. Then, the inlet pressure of each channel is calculated using the relationship "inlet pressure = friction drop + back pressure". Finally, this inlet pressure is used as the outlet pressure boundary condition of the splitting numerical model, because the outlet pressure of the splitting model needs to match the inlet pressure of the channel to ensure the continuity of the physical field. Its function is to complete the closed-loop transfer of "convergence parameters - channel parameters - splitting parameters", update the boundary conditions of the splitting model, provide more accurate input for the next iteration calculation, and promote the coupled calculation towards convergence.

[0028] Step 5: Repeat steps 3-4 for iterative calculation until the error of the mass flow rate of each channel in two adjacent iterations is less than the limit value. If it is less, end the coupled simulation calculation to obtain the three-dimensional physical field distribution of the split numerical model and the confluence numerical model, as well as the flow heat transfer parameters and heat transfer of the working fluid in each channel. Then, check whether the heat transfer of each parallel channel of the condenser meets the design requirements under the condition of uneven flow distribution.

[0029] After each iteration, the error of the mass flow rate of each channel is compared between two adjacent iterations. When the error is less than a limit value (e.g., 10), the error is considered closed. -3 When the convergence is achieved, it indicates that the physical field and parameters of the entire system (branching and merging + channels) have reached a stable matching state, and the coupled calculation has converged. Its function is to ensure the accuracy and reliability of the calculation results. The three-dimensional physical field distribution of the branching and merging (reflecting the detailed physical field of the branching and merging regions), as well as the flow heat transfer parameters and heat transfer of each channel, output after convergence can be directly used to verify whether the heat transfer of the condenser meets the design requirements when the flow distribution is uneven. It provides a key basis for condenser structure optimization (such as adjusting the branching and merging structure and channel size).

[0030] The simulation method presented in this application achieves coupling through multi-dimensional simulation, enabling the optimal estimation of flow and heat transfer information within the parallel channels of the condenser, while simultaneously obtaining detailed physical field information of the condenser inlet and outlet. For those more concerned with the detailed physical field changes of the condenser inlet and outlet structures under transient conditions, the optimal estimated boundary conditions provided in real-time by the single-channel model are more accurate and convenient than manually input boundary conditions. For those more concerned with the flow distribution characteristics of the parallel channels under steady-state conditions, computational fluid dynamics numerical simulation yields detailed physical results for the inlet and outlet, resulting in flow distribution characteristics of the parallel channels that more closely approximate reality. This method has significant reference value and guiding significance for global simulation methods of condenser flow distribution.

[0031] In some embodiments, a heat transfer and resistance model is constructed based on the dimensions and structure of the parallel channels of the condenser and combined with the heat transfer characteristics of the working fluid flow. A single-channel model of the condenser is then constructed based on the heat transfer and resistance model, including: Based on the dimensions and structure of the parallel channels of the condenser, and using a length-divided segmentation method, different empirical correlations for flow heat transfer are used to construct heat transfer and resistance models for the condenser channels in different zones, thereby forming a single-channel condenser model.

[0032] Based on the heat transfer and resistance model of the condenser channel, a single-channel model of the condenser is constructed by combining the dimensions and structure of the parallel channels of the condenser.

[0033] First, considering the actual dimensions and structure of the parallel channels of the condenser, a segmentation method based on length is adopted—this is because the flow and heat transfer characteristics of the working fluid differ significantly in different regions (e.g., the superheated zone is a single-phase superheated state, the two-phase zone has gas-liquid condensation phase change, and the subcooled zone is a single-phase subcooled state). Appropriate empirical correlations for flow and heat transfer (e.g., formulas for calculating heat transfer coefficients and resistance coefficients in different regions) need to be selected for the characteristics of each region. This allows for the construction of a channel heat transfer and resistance model that accurately reflects the heat transfer laws and flow resistance in each region. Then, using this heat transfer and resistance model as the core, and combining it with the specific dimensions (e.g., channel length, cross-sectional size) and structure (e.g., channel configuration, whether there is a finned structure) of the parallel channels, the model parameters are further refined, ultimately constructing a single-channel condenser model. This single-channel model not only closely matches the actual channel structure but also accurately describes the flow and heat transfer process of the working fluid in different heat transfer regions.

[0034] In some embodiments, based on the structure of the condenser inlet and outlet regions, a flow splitting numerical model and a flow combining numerical model of the condenser are constructed, including: A three-dimensional geometric model of the flow splitting zone is constructed based on the structure of the condenser inlet region, and a three-dimensional geometric model of the flow convergence zone is constructed based on the structure of the condenser outlet region. Mesh the 3D model of the shunt and the 3D model of the confluence to obtain the numerical model of the shunt and the numerical model of the confluence.

[0035] First, a 3D model of the flow splitting region is constructed based on the actual structure of the condenser inlet area (such as the shape and size of the inlet flow channel and its connection with parallel channels). Then, a 3D model of the flow convergence region is constructed based on the actual structure of the outlet region (such as the shape and size of the outlet flow channel and its connection with parallel channels). This ensures that the models accurately reproduce the geometric features of the flow splitting and convergence regions. Next, the constructed 3D models of the flow splitting and convergence are meshed. By decomposing the 3D geometric model into countless small mesh units, the complex physical field calculations are transformed into numerical calculations for each mesh unit. This results in 3D numerical models of the flow splitting and convergence regions that can be used for subsequent numerical simulations. The 3D geometric model ensures that the calculation scenario of the physical field in the flow splitting and convergence regions is consistent with reality, while a reasonable mesh division ensures the accuracy and efficiency of the numerical simulation calculations, avoiding deviations in the calculation of physical field parameters (such as pressure and velocity distribution) due to geometric distortion or mesh quality issues. This allows for the acquisition of a stable initial field distribution of the flow splitting and convergence structures, enabling cross-dimensional coupled simulation calculations.

[0036] In some embodiments, numerical simulations are performed on the shunt numerical model and the confluence numerical model, respectively, including: The inlet boundary condition for both the split-flow numerical model and the confluence numerical model is a mass flow rate inlet, and the outlet boundary condition is a pressure outlet. Furthermore, the inlet mass flow rate and outlet pressure are the same for both models.

[0037] In some embodiments, the inlet pressure of each channel is determined based on the back pressure and the pressure drop along the working medium in each channel. The inlet pressure is calculated as follows:

[0038] In the formula: P i,new — Updated inlet pressure values ​​for each channel (Pa); Δ P i — Pressure drop along each channel / Pa; P i,back — Back pressure of each channel / Pa.

[0039] This application provides a method for calculating flow distribution in microchannel condensers based on cross-dimensional coupled simulation. It establishes a channel heat transfer and resistance model using a one-dimensional two-phase flow heat transfer calculation program, and performs three-dimensional simulation analysis of the flow distribution structure using computational fluid dynamics software. A user-defined function (UDF) program is used to transfer boundary parameters between the one-dimensional two-phase flow heat transfer calculation program and the three-dimensional numerical simulation of the flow distribution structure. Coupled iterative solutions are used to obtain the flow distribution of parallel channels and its impact on the condenser's heat transfer, achieving cross-dimensional coupled simulation analysis of flow distribution in parallel channels of the condenser from one-dimensional to three-dimensional.

[0040] Example 1 The following combination Figure 1 A simplified schematic diagram of the solid and fluid domains of a microchannel condenser is shown, and Figure 2 The diagram shown illustrates the condenser's flow distribution structure and channel steady-state calculation. It provides a further detailed description of the condenser parallel channel flow distribution method based on steady-state coupling simulation of the present invention. In this embodiment, the one-dimensional two-phase flow steady-state flow heat transfer calculation program is referred to as the one-dimensional program, and the user-defined function program is referred to as the UDF program.

[0041] A global simulation method for flow distribution in a microchannel condenser includes the following steps: Step 1: Based on the dimensions and structure of the parallel channels of the condenser, and using the length-segmentation method, different empirical correlations for flow heat transfer are used to establish heat transfer and resistance models for different zones. Based on the heat transfer and resistance models of the condenser channels, a single-channel model of the condenser is constructed by combining the dimensions and structure of the parallel channels of the condenser.

[0042] A coupled computational communication interface was established, and a one-dimensional program was created using software such as MATLAB to simulate and calculate the steady-state results of the condenser channel under different inlet boundary parameters, thereby obtaining key parameters such as the pressure drop of the working fluid along the flow path and the overall heat transfer.

[0043] Step 2: For the inlet and outlet areas of the condenser, use preprocessing software, i.e. geometric modeling software such as ANSYS SpaceClaim, to establish a three-dimensional geometric model of the condenser's flow distribution and merging; use mesh generation software such as ANSYS Mesh to perform mesh generation on it. The mesh model can be divided into full hexahedral mesh, full tetrahedral mesh, and mixed mesh as needed to obtain the numerical model of the condenser's flow distribution and merging. The condenser flow splitting and busbar numerical model includes the flow splitting numerical model and the flow busbar numerical model.

[0044] Step 3: Import the condenser manifold numerical model into computational fluid dynamics software such as Fluent; For the three-dimensional numerical simulation of the splitting numerical model, the inlet boundary condition is the mass flow rate inlet, and the outlet boundary condition is the pressure outlet. Monitors are set to monitor the mass flow rate of multiple outlets, which is used as the criterion for initial calculation convergence. Given the inlet mass flow rate and the same outlet pressure, the stable initial field distribution of the splitting structure is obtained. For the three-dimensional numerical simulation of the confluence numerical model, the inlet boundary condition is the mass flow rate inlet and the outlet boundary condition is the pressure outlet. Given the same inlet mass flow rate and outlet pressure, the stable initial field distribution of the confluence structure is obtained. Step 4: Three-dimensional numerical simulation based on the split numerical model, setting up the coupling calculation communication interface in the UDF program, setting pressure boundary conditions, and obtaining the mass flow rate of each channel; Three-dimensional numerical simulation based on the split numerical model: setting up a coupled calculation communication interface in the UDF program, setting the mass flow boundary conditions for each channel, and obtaining the pressure of each channel. Step 5: with Figure 3 and Figure 4 As shown, based on the one-dimensional program established in steps 1-4, and the flow splitting numerical model and the flow merging numerical model, cross-dimensional steady-state coupling calculations are carried out. The specific steps are as follows: S5.1: Based on the stable initial field distribution obtained from the three-dimensional numerical simulation of the split numerical model in step 3, the mass flow rate of each channel is obtained using the UDF program, and these data are transmitted to the one-dimensional program, waiting to receive data. S5.2: After receiving the mass flow rate of each channel in step S5.1, the one-dimensional program uses the UDF program to transmit these data to the bus numerical model, and then waits to receive data. S5.3: After receiving the mass flow rate of each channel, the bus numerical model uses the UDF program to set these data as the inlet mass flow rate boundary conditions of the corresponding channel, performs simulation calculations, uses the UDF program to obtain the calculated back pressure of each channel, and transmits these data to the one-dimensional program, waiting to receive data. S5.4: After receiving the back pressure of each channel in step S5.3, the one-dimensional program combines the mass flow rate of each channel received in step S5.1 to perform simulation calculations on the single-channel model of the condenser, and can obtain the pressure drop of the working fluid along the flow path of each channel.

[0045] It should be noted that during the simulation calculation, a single-channel condenser model was used to simulate the mass flow rate and back pressure of each channel to obtain the pressure drop of the working fluid along the corresponding channel.

[0046] The inlet pressure of each channel is calculated based on the back pressure and pressure drop of the working medium along the flow path. The inlet pressure of each channel is then transmitted to the shunt numerical model using a UDF program. After transmission, the model waits to receive data. The formulas for calculating the inlet pressure of each channel are as follows:

[0047] In the formula: P i,new — Updated inlet pressure values ​​for each channel (Pa); Δ P i — Pressure drop along each channel / Pa; P i,back — Back pressure of each channel / Pa.

[0048] S5.5: After receiving the inlet pressure of each channel, the shunt numerical model uses the UDF program to set the inlet pressure as the boundary condition of the corresponding channel's outlet pressure, and completes one iteration calculation. Step 6: Repeat S5.1-S5.5, compare the key calculation results in the three-dimensional numerical simulation of the split-flow and merge-flow structure in the two adjacent iterations, and determine whether convergence has been achieved. Specifically, this includes: determining whether the error of the mass flow rate of each channel in the two adjacent iterations is less than the limit value. If it is less, the coupled simulation calculation is terminated, and the three-dimensional physical field distribution of the split-flow numerical model and the merge-flow numerical model, as well as the flow heat transfer parameters and heat transfer of the working fluid in each channel are obtained. Then, the heat transfer of each parallel channel of the condenser under the condition of uneven flow distribution is checked to see if it meets the design requirements.

[0049] This method can perform one-dimensional modeling and calculation of the microchannel condenser channel structure while simultaneously performing three-dimensional modeling and simulation of the key inlet and outlet flow distribution structures. It can quickly and accurately obtain local information of the condenser inlet and outlet flow distribution structures, guiding the overall flow and heat transfer design research and structural optimization of the condenser. In addition, the boundary parameters are exchanged after each iteration step of the program, making the implementation simple. After the program coupling simulation is completed, the calculation model can be adjusted by setting different input conditions to obtain calculation results under different operating conditions.

[0050] Secondly, this method can be used with existing computational fluid dynamics software and programming platforms, such as Fluent and MATLAB; and the computational fluid dynamics software and flow heat transfer calculation program are relatively independent, and can be calculated separately, with low computational resource consumption, fast calculation speed and high accuracy of calculation results.

[0051] The cross-dimensional coupling simulation method proposed in this invention is applicable to the prediction of flow heat transfer characteristics when the flow rate of a microchannel condenser is non-uniform. This method not only realizes the calculation of flow heat transfer characteristics when the flow rate of a microchannel condenser is non-uniform, but also solves the limitations of one-dimensional theoretical calculation and analysis.

[0052] Example 2 This application also provides a global simulation system for flow distribution in a microchannel condenser, including the following steps: The model building module is used to build heat transfer and resistance models based on the dimensions and structure of the parallel channels of the condenser and the heat transfer characteristics of the working fluid flow, and to build a single-channel model of the condenser based on the heat transfer and resistance models. Based on the structure of the inlet and outlet areas of the condenser, construct the flow splitting numerical model and the flow combining numerical model of the condenser. The simulation module is used to determine the stable initial field distribution of the shunt structure and the stable initial field distribution of the confluence structure based on the shunt numerical model and the confluence numerical model, respectively. The back pressure module is used to determine the mass flow rate of each channel based on the stable initial field distribution of the split structure. The mass flow rate of each channel is used as the boundary condition of the inlet mass flow rate of each channel in the condenser numerical model. The condenser numerical model is then simulated to obtain the back pressure of each channel of the condenser. The outlet pressure module is used to input the back pressure and mass flow rate of each channel into the inlet boundary parameters of the condenser single-channel model, perform simulation calculations on the condenser single-channel model to determine the inlet pressure of each channel, and update the outlet pressure boundary conditions of the split numerical model based on the inlet pressure. The iteration module is used to repeatedly execute the simulation module, back pressure module, and outlet pressure module until the mass flow rate of each channel meets the requirements, thereby obtaining the fluid dynamic parameters of the split numerical model and the confluence numerical model, as well as the working fluid flow and heat transfer parameters of the channel.

[0053] It should be noted that, in the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another device, or some features may be ignored or not executed. The modules described as separate components may or may not be physically separated. The components shown as modules may be one or more physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the modules can be selected to achieve the purpose of the solution in this embodiment according to actual needs.

[0054] Furthermore, in the various embodiments of the present invention, the modules can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The integrated unit described above can be implemented in hardware or as a software functional unit.

[0055] An electronic device provided in this application includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the global simulation method for microchannel condenser flow distribution as described in any of the above embodiments.

[0056] Another electronic device provided in this application embodiment may further include: an input port connected to a processor for transmitting multimodal data collected by an external acquisition device to the processor; a display unit connected to the processor for displaying the processor's processing results to the outside world; and a communication module connected to the processor for enabling communication between the electronic device and the outside world. The display unit may be a display panel, a laser scanning display, etc.; the communication method adopted by the communication module includes, but is not limited to, Mobile High Definition Link (HML), Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), and wireless connection (including Wi-Fi, Bluetooth, Bluetooth Low Energy, and IEEE 802.11s-based communication technology).

[0057] This application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the steps of the global simulation method for microchannel condenser flow distribution as described in any of the above embodiments.

[0058] For descriptions of relevant parts in the global simulation method for microchannel condenser flow distribution, electronic devices, and computer-readable storage media provided in this application's embodiments, please refer to the detailed description of the corresponding parts in the global simulation method for microchannel condenser flow distribution provided in this application's embodiments; they will not be repeated here. Furthermore, parts of the technical solutions provided in this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0059] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A global simulation method for flow distribution in a microchannel condenser, characterized in that, Includes the following steps: Step 1: Construct a heat transfer and resistance model based on the dimensions and structure of the parallel channels of the condenser and the heat transfer characteristics of the working fluid flow; and construct a single-channel model of the condenser based on the heat transfer and resistance model. Based on the structure of the inlet and outlet areas of the condenser, construct the flow splitting numerical model and the flow combining numerical model of the condenser. Step 2: Based on the shunt numerical model and the confluence numerical model, determine the stable initial field distribution of the shunt structure and the stable initial field distribution of the confluence structure, respectively. Step 3: Determine the mass flow rate of each channel based on the stable initial field distribution of the split structure, use the mass flow rate of each channel as the boundary condition of the inlet mass flow rate of each channel in the condenser numerical model, and perform simulation calculations on the condenser numerical model to obtain the back pressure of each channel of the condenser. Step 4: Input the back pressure and mass flow rate of each channel into the inlet boundary parameters of the condenser single-channel model, perform simulation calculations on the condenser single-channel model to determine the inlet pressure of each channel, and update the outlet pressure boundary conditions of the split numerical model according to the inlet pressure. Step 5: Repeat steps 2-4 for iterative calculations until the mass flow rate of each channel meets the requirements, and obtain the fluid dynamic parameters of the split numerical model and the confluence numerical model, as well as the working fluid flow and heat transfer parameters of the channels.

2. The global simulation method for flow distribution in a microchannel condenser according to claim 1, characterized in that, The construction of the single-channel condenser model based on the heat transfer and resistance model includes: Based on the dimensions and structure of the parallel channels of the condenser, and using a length-divided segmentation method, different empirical correlations for flow heat transfer are applied to different zones to construct a heat transfer and resistance model of the working fluid within the condenser channel, thereby forming a single-channel condenser model.

3. The global simulation method for flow distribution in a microchannel condenser according to claim 1, characterized in that, The process of constructing the condenser's flow splitting and confluence numerical models based on the condenser's inlet and outlet area structure includes: A three-dimensional geometric model of the flow splitting zone is constructed based on the structure of the condenser inlet region, and a three-dimensional geometric model of the flow convergence zone is constructed based on the structure of the condenser outlet region. Mesh the 3D geometric models of the shunt and the confluence to obtain the numerical models of the shunt and the confluence.

4. The global simulation method for flow distribution in a microchannel condenser according to claim 1, characterized in that, The numerical simulation calculations for the shunting numerical model and the merging numerical model respectively include: The inlet boundary conditions of the splitting numerical model and the confluence numerical model are set as mass flow rate inlet and pressure outlet boundary conditions, and the inlet mass flow rate and outlet pressure of the splitting numerical model and the confluence numerical model are the same. The splitting numerical model and the confluence numerical model are numerically simulated using fluid dynamics software to obtain the corresponding stable initial field distribution.

5. The global simulation method for flow distribution in a microchannel condenser according to claim 1, characterized in that, The inlet pressure of each channel is determined based on the back pressure and the pressure drop of the working medium along the flow path. The calculation method for the inlet pressure is as follows: In the formula: P i,new Update the inlet pressure values ​​for each channel; Δ P i For the pressure drop along each channel; P i,back This refers to the back pressure of each channel.

6. The global simulation method for flow distribution in a microchannel condenser according to claim 1, characterized in that, The quality flow rate requirements for each channel are as follows: If the error of the mass flow rate of each channel obtained in two adjacent iterations is less than the limit value, the three-dimensional physical field distribution of the split numerical model and the confluence numerical model, as well as the flow heat transfer parameters and heat transfer of the working fluid in each channel are obtained.

7. The global simulation method for flow distribution in a microchannel condenser according to claim 1, characterized in that, The fluid dynamics data and flow heat transfer parameters of the splitting and merging numerical models include: The fluid dynamics data is a three-dimensional physical field distribution; The flow heat transfer parameters include the flow heat transfer parameters and heat transfer capacity of the working fluid in each channel; Based on the three-dimensional physical field distribution of the split-flow numerical model and the confluence numerical model, the flow heat transfer parameters and heat transfer of the working fluid in each channel are used to verify whether the heat transfer of each parallel channel of the condenser meets the design requirements under the condition of uneven flow distribution.

8. A global simulation system for flow distribution in a microchannel condenser, characterized in that, Includes the following steps: The model building module is used to build heat transfer and resistance models based on the dimensions and structure of the parallel channels of the condenser and the heat transfer characteristics of the working fluid flow, and to build a single-channel model of the condenser based on the heat transfer and resistance models. Based on the structure of the inlet and outlet areas of the condenser, construct the flow splitting numerical model and the flow combining numerical model of the condenser. The simulation module is used to determine the stable initial field distribution of the shunt structure and the stable initial field distribution of the confluence structure based on the shunt numerical model and the confluence numerical model, respectively. The back pressure module is used to determine the mass flow rate of each channel based on the stable initial field distribution of the split structure. The mass flow rate of each channel is used as the boundary condition of the inlet mass flow rate of each channel in the condenser numerical model. The condenser numerical model is then simulated to obtain the back pressure of each channel of the condenser. The outlet pressure module is used to input the back pressure and mass flow rate of each channel into the inlet boundary parameters of the condenser single-channel model, perform simulation calculations on the condenser single-channel model to determine the inlet pressure of each channel, and update the outlet pressure boundary conditions of the split numerical model based on the inlet pressure. The iteration module is used to repeatedly execute the simulation module, back pressure module, and outlet pressure module until the mass flow rate of each channel meets the requirements, thereby obtaining the fluid dynamic parameters of the split numerical model and the confluence numerical model, as well as the working fluid flow and heat transfer parameters of the channel.

9. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor, configured to implement the steps of the global simulation method for microchannel condenser flow distribution as described in any one of claims 1-8 when executing the computer program.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the global simulation method for microchannel condenser flow distribution as described in any one of claims 1-8.

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