Quantification method and device for refrigerant flow distribution in plate heat exchanger

Abstract

The application discloses a plate heat exchanger refrigerant flow distribution quantification method and device, which is applied to the technical field of plate heat exchangers and comprises the following steps: acquiring the temperature value and local heat transfer coefficient of each plate channel in the plate heat exchanger and the total pressure drop value of each flow path in the plate heat exchanger; if the total pressure drop values of the flow paths are all different, adjusting the gas refrigerant flow value of each plate channel by using the total pressure drop values of the flow paths, and returning to the first step; otherwise, obtaining the outer wall surface temperature distribution of the plate heat exchanger according to the temperature value and the local heat transfer coefficient of each plate channel; if the outer wall surface temperature distribution is inconsistent with the side wall surface infrared image of the plate heat exchanger, adjusting the liquid refrigerant flow value of each plate channel by using the outer wall surface temperature distribution and the side wall surface infrared image, and returning to the first step; otherwise, outputting the gas refrigerant flow value and the liquid refrigerant flow value of each plate channel. The application can effectively improve the flow distribution quantification precision of the gas-liquid two-phase refrigerant in the plate heat exchanger.

Description

Technical Field

[0001] This application relates to the field of plate heat exchanger technology, and in particular to a method and apparatus for quantifying refrigerant flow distribution in a plate heat exchanger. Background Technology

[0002] Plate heat exchangers are constructed by stacking and brazing multiple corrugated metal plates. The inlet and outlet holes of the corrugated metal plates form the inlet manifold and outlet manifold for the refrigerant and hot fluids, respectively. The space between two adjacent corrugated metal plates is a plate channel for non-contact heat exchange between the fluids on both sides.

[0003] In plate heat exchangers, uneven flow distribution of the gas-liquid two-phase refrigerant among the plate channels is a common problem. Uneven flow distribution refers to the inconsistent refrigerant flow rate in each of the parallel plate channels when the refrigerant enters through the inlet manifold. Typically, the refrigerant enters the plate heat exchanger from the lower left inlet manifold, flows upwards in the plate channels for heat exchange and evaporation, and then flows out from the upper left outlet manifold. In plate channels with a high liquid refrigerant flow rate, the heat exchange area required for complete evaporation into the superheated state is large, resulting in a larger proportion of the two-phase region; conversely, in plate channels with a low liquid refrigerant flow rate, the heat exchange area required for complete evaporation into the superheated state is small, resulting in a smaller proportion of the two-phase region. Generally, the more uniform the refrigerant distribution, the greater the heat exchange capacity, the smaller the pressure loss, and the better the overall performance of the plate heat exchanger. Therefore, accurately quantifying the flow distribution of the gas-liquid two-phase refrigerant within a plate heat exchanger is crucial. Summary of the Invention

[0004] This application provides a method and apparatus for quantifying refrigerant flow distribution in a plate heat exchanger, which can effectively improve the accuracy of flow distribution quantification of gas-liquid two-phase refrigerant in a plate heat exchanger.

[0005] On one hand, this application provides a method for quantifying refrigerant flow distribution in a plate heat exchanger, applied to the plate heat exchanger. The plate heat exchanger includes multiple plate channels and multiple flow paths, with each flow path corresponding to one of the multiple plate channels. Each plate channel is the space between two adjacent corrugated metal plates in the plate heat exchanger. Each flow path consists of the inlet manifold of the plate heat exchanger, the plate channel corresponding to the flow path, and the outlet manifold of the plate heat exchanger. The method includes:

[0006] Obtain the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path;

[0007] If the total pressure drop values ​​of each flow path are different, the gas refrigerant flow rate of each plate channel is adjusted using the total pressure drop values ​​of each flow path, and the process returns to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path; otherwise, the temperature distribution of the outer wall of the plate heat exchanger is obtained based on the temperature value and local heat transfer coefficient of each plate channel.

[0008] If the temperature distribution of the outer wall surface and the infrared image of the side wall surface of the plate heat exchanger are inconsistent, the liquid refrigerant flow rate of each plate channel is adjusted using the temperature distribution of the outer wall surface and the infrared image of the side wall surface, and the process returns to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path; otherwise, the gas refrigerant flow rate and liquid refrigerant flow rate of each plate channel are output.

[0009] Further, in one embodiment, obtaining the temperature value and local heat transfer coefficient of each of the plate channels, and the total pressure drop value of each of the flow paths, includes:

[0010] Each of the plate channels is divided into multiple units along the length of the plate heat exchanger; wherein, the multiple plate channels include multiple hot side plate channels and multiple refrigerant side plate channels, each of the hot side plate channels includes multiple hot side units connected sequentially along the flow direction of the hot side fluid of the plate heat exchanger, and each of the refrigerant side plate channels includes multiple refrigerant side units connected sequentially along the flow direction of the gaseous refrigerant;

[0011] The inlet temperature value of each of the aforementioned hot-side units is set to a preset temperature value;

[0012] For each of the refrigerant side plate channels, obtain the heat transfer value of each refrigerant side unit in the current refrigerant side plate channel and its two adjacent heat side units, as well as the outlet temperature value of each refrigerant side unit in the current refrigerant side plate channel;

[0013] For each of the hot side plate channels, the outlet temperature value of each of the hot side units in the current hot side plate channel is updated according to the heat exchange value between each of the hot side units in the current hot side plate channel and its two adjacent refrigerant side units.

[0014] If the temperature distribution of each of the plate channels does not meet the preset conditions, the process returns to the step of obtaining the heat transfer value of each refrigerant-side unit in the current refrigerant-side plate channel and its two adjacent heat-side units, as well as the outlet temperature value of each refrigerant-side unit in the current refrigerant-side plate channel. Otherwise, the outlet temperature value of each unit in each plate channel is output as the temperature value of each plate channel, and the local heat transfer coefficient of each plate channel is determined based on the heat transfer value of each refrigerant-side unit in each refrigerant-side plate channel and its two adjacent heat-side units.

[0015] Further, in one embodiment, obtaining the temperature value and local heat transfer coefficient of each of the plate channels, and the total pressure drop value of each of the flow paths, includes:

[0016] The total pressure drop of the target flow path is obtained based on the total pressure drop of the inlet manifold corresponding to the target flow path, the total pressure drop of the outlet manifold corresponding to the target flow path, and the internal pressure drop of the plate channel corresponding to the target flow path.

[0017] Wherein, the target flow path is any one of the flow paths; the inlet manifold corresponding to the target flow path is the inlet manifold section from the inlet of the plate heat exchanger to the plate channel corresponding to the target flow path; the outlet manifold corresponding to the target flow path is the outlet manifold section from the plate channel corresponding to the target flow path to the outlet of the plate heat exchanger.

[0018] Further, in one embodiment, adjusting the gas refrigerant flow rate of each plate channel using the total pressure drop value of each of the flow paths includes:

[0019] The average total pressure drop across all flow paths is taken as the average flow path pressure drop.

[0020] Based on the average pressure drop of the flow path and the total pressure drop of each flow path, the gas refrigerant flow rate of each plate channel is adjusted to obtain the adjusted gas refrigerant flow rate of each plate channel as the new gas refrigerant flow rate of each plate channel.

[0021] Further, in one embodiment, obtaining the temperature distribution of the outer wall surface of the plate heat exchanger based on the temperature value and local heat transfer coefficient of each of the plate channels includes:

[0022] Based on the temperature values ​​of each of the plate channels, the hot-side fluid temperature field of the plate heat exchanger is determined, and based on the local heat transfer coefficient of each of the plate channels, the heat transfer coefficient field of the plate heat exchanger is determined.

[0023] Based on the finite difference method, a three-dimensional computational mesh is established for the sidewall of the plate heat exchanger, and the temperature field of the hot-side fluid and the heat transfer coefficient field are mapped to the three-dimensional computational mesh.

[0024] Using the three-dimensional computational grid, the three-dimensional steady-state heat conduction differential equation without internal heat source and its boundary conditions of the plate heat exchanger are solved iteratively to obtain the overall temperature distribution of the side wall of the plate heat exchanger.

[0025] The two-dimensional temperature distribution of the outer plane is extracted from the overall temperature distribution of the sidewall as the temperature distribution of the outer wall.

[0026] Furthermore, in one embodiment, the method further includes:

[0027] The error value between the temperature distribution on the outer wall surface and the infrared image of the side wall surface is obtained as the target error value;

[0028] If the target error value is less than a preset error threshold, it is determined that the temperature distribution of the outer wall surface is consistent with the infrared image of the side wall surface; otherwise, it is determined that the temperature distribution of the outer wall surface is inconsistent with the infrared image of the side wall surface.

[0029] Further, in one embodiment, adjusting the liquid refrigerant flow rate of each of the plate channels using the temperature distribution of the outer wall and the infrared image of the outer wall includes:

[0030] Based on the automatic differentiation method, the partial derivative of the target error value with respect to the liquid refrigerant flow rate value of each of the plate channels is obtained; wherein, the target error value is the error value between the temperature distribution of the outer wall and the infrared image of the side wall;

[0031] Based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each of the plate channels, the liquid refrigerant flow rate of each of the plate channels is adjusted to obtain the adjusted liquid refrigerant flow rate of each of the plate channels as the new liquid refrigerant flow rate of each of the plate channels.

[0032] Further, in one embodiment, adjusting the liquid refrigerant flow rate of each plate channel based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel, to obtain the adjusted liquid refrigerant flow rate of each plate channel as the new liquid refrigerant flow rate of each plate channel, includes:

[0033] The average liquid refrigerant flow rate of all the plate channels is obtained as the average liquid refrigerant flow rate.

[0034] The adaptive step size is obtained based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each of the plate channels and the average liquid refrigerant flow rate.

[0035] Based on the adaptive step size and the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel, unconstrained gradient descent processing is performed on the liquid refrigerant flow rate of each plate channel to obtain the intermediate variable vector of each plate channel.

[0036] The intermediate variable vectors of each plate channel are subjected to simplex projection processing to obtain the adjusted liquid refrigerant flow rate value of each plate channel, which is then used as the new liquid refrigerant flow rate value of each plate channel.

[0037] Further, in one embodiment, the step of performing simplex projection processing on the intermediate variable vectors of each plate channel to obtain the adjusted liquid refrigerant flow rate value of each plate channel as the new liquid refrigerant flow rate value of each plate channel includes:

[0038] The intermediate variable vectors of each of the aforementioned plate channels are sorted and their positions are located to obtain the optimal truncation position;

[0039] Based on the optimal cutoff position and the total flow rate of the liquid refrigerant, the Lagrange multiplier is obtained;

[0040] Based on the Lagrange multipliers and the intermediate variable vectors of each plate channel, the adjusted liquid refrigerant flow rate value of each plate channel is obtained as the new liquid refrigerant flow rate value of each plate channel.

[0041] On the other hand, embodiments of this application provide a refrigerant flow distribution quantification device for a plate heat exchanger. The plate heat exchanger includes multiple plate channels and multiple flow paths, with each flow path corresponding one-to-one with a plate channel. Each plate channel is the space between two adjacent corrugated metal plates in the plate heat exchanger. Each flow path consists of the inlet manifold of the plate heat exchanger, the plate channel corresponding to the flow path, and the outlet manifold of the plate heat exchanger. The device includes:

[0042] The acquisition module is used to acquire the temperature value and local heat transfer coefficient of each of the plate channels, as well as the total pressure drop value of each of the flow paths;

[0043] The first processing module is used to adjust the gas refrigerant flow rate of each plate channel by using the total pressure drop value of each flow path if the total pressure drop value of each flow path is different, and return to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel and the total pressure drop value of each flow path; otherwise, it obtains the temperature distribution of the outer wall surface of the plate heat exchanger based on the temperature value and local heat transfer coefficient of each plate channel.

[0044] The second processing module is used to adjust the liquid refrigerant flow rate of each plate channel by using the temperature distribution of the outer wall and the infrared image of the side wall of the plate heat exchanger if the temperature distribution of the outer wall and the infrared image of the side wall are inconsistent, and to trigger the acquisition module to obtain the temperature value and local heat transfer coefficient of each plate channel and the total pressure drop value of each flow path; otherwise, it outputs the gas refrigerant flow rate and liquid refrigerant flow rate of each plate channel.

[0045] According to an embodiment of this application, a method and apparatus for quantifying refrigerant flow distribution in a plate heat exchanger are provided. The method obtains the temperature value and local heat transfer coefficient of each plate channel in the plate heat exchanger, as well as the total pressure drop value of each flow path in the plate heat exchanger. If the total pressure drop values ​​of each flow path are different, the gas refrigerant flow rate of each plate channel is adjusted using the total pressure drop values ​​of each flow path, and the process returns to the first step. Otherwise, the temperature distribution of the outer wall surface of the plate heat exchanger is obtained based on the temperature value and local heat transfer coefficient of each plate channel. If the temperature distribution of the outer wall surface is inconsistent with the infrared image of the side wall surface of the plate heat exchanger, the liquid refrigerant flow rate of each plate channel is adjusted using the temperature distribution of the outer wall surface and the infrared image of the side wall surface, and the process returns to the first step. Otherwise, the gas refrigerant flow rate value and liquid refrigerant flow rate value of each plate channel are output. This application calculates the flow rate of gas-liquid two-phase refrigerant in each plate channel by matching the infrared image of the heat exchanger side wall obtained from field measurement in the simulation calculation model of the plate heat exchanger. This allows for precise distribution of the flow rate of gas-liquid two-phase refrigerant in the plate heat exchanger without intrusion, effectively improving the quantitative accuracy of the flow rate distribution of gas-liquid two-phase refrigerant in the plate heat exchanger. Attached Figure Description

[0046] Figure 1 This is a structural example diagram of a plate heat exchanger;

[0047] Figure 2 This is an example image of the infrared image of the side wall of a plate heat exchanger;

[0048] Figure 3 This is a flowchart of a method for quantifying refrigerant flow distribution in a plate heat exchanger, as provided in this application.

[0049] Figure 4 This is a schematic diagram illustrating the calculation principle of the heat transfer value within the plate channel provided in this application;

[0050] Figure 5 This is a schematic diagram of the heat exchange principle between the plate channels provided in this application;

[0051] Figure 6 This is a schematic diagram illustrating the calculation principle of the total pressure drop value of each flow path provided in this application;

[0052] Figure 7This is a flowchart illustrating the implementation process of a method for quantifying refrigerant flow distribution in a plate heat exchanger, as provided in this application.

[0053] Figure 8 This is a comparison chart of heat exchange provided in this application;

[0054] Figure 9 This is a comparison diagram of the sidewall temperature distribution provided in this application;

[0055] Figure 10 This is an example diagram of the temperature distribution on the side wall of a plate heat exchanger under overall 0K superheated conditions, as provided in this application. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0057] The present application will be further described below with reference to the accompanying drawings and specific embodiments. The described embodiments should not be considered as limitations on the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present application.

[0058] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0060] The structure of a plate heat exchanger is as follows Figure 1 As shown, Figure 1 In red, the hot-side fluid is represented, and in blue, the cold (refrigerant)-side fluid is represented. This type of heat exchanger is constructed by stacking and brazing multiple corrugated metal plates. The inlet and outlet holes of the multiple corrugated metal plates form the inlet manifold and outlet manifold for the refrigerant-side and hot-side fluids, respectively. The space between two adjacent corrugated metal plates is a plate channel for non-contact heat exchange between the fluids on both sides.

[0061] In plate heat exchangers, uneven flow distribution of the gas-liquid two-phase refrigerant between the plate channels is a common problem. The more uniform the refrigerant flow distribution between the plate channels, the higher the heat exchange capacity, the smaller the pressure drop, the higher the efficiency, and the better the product performance. Specifically, uneven flow distribution refers to the inconsistent refrigerant flow rate in each plate channel when the refrigerant enters multiple parallel plate channels through the inlet manifold. This problem is particularly severe when the plate heat exchanger is used as an evaporator in a vapor compression refrigeration and air conditioning system, and can be visually displayed through infrared images of the plate heat exchanger's sidewalls. Typically, the refrigerant enters the plate heat exchanger from the inlet manifold in the lower left corner, flows upwards in the plate channels for heat exchange and evaporation, and then flows out from the outlet manifold in the upper left corner. Figure 2 As shown in the infrared images of the sidewalls, in plate channels with high liquid refrigerant flow rates, the heat exchange area required for complete evaporation and superheating of the liquid refrigerant is large, resulting in a large proportion of the two-phase region. Conversely, in plate channels with low liquid refrigerant flow rates, the heat exchange area required for complete evaporation and superheating is small, resulting in a smaller proportion of the two-phase region. Generally, the more uniform the refrigerant distribution, the greater the heat transfer capacity and the lower the pressure loss of the plate heat exchanger, leading to better overall performance. Therefore, accurately quantifying the flow distribution of the gas-liquid two-phase refrigerant within a plate heat exchanger is crucial.

[0062] To address this, this application provides a method and apparatus for quantifying refrigerant flow distribution in a plate heat exchanger. This method calculates the gas-liquid two-phase refrigerant flow rate in each plate channel by matching the infrared image of the heat exchanger sidewall obtained from on-site measurements with the plate heat exchanger simulation model. This allows for precise distribution of the gas-liquid two-phase refrigerant flow rate within the plate heat exchanger without intrusion, and features non-invasiveness, high accuracy, and broad applicability.

[0063] Reference Figure 3 , Figure 3 This is a flowchart of a method for quantifying refrigerant flow distribution in a plate heat exchanger, as provided in this application. This method is applied to applications such as... Figure 1 The plate heat exchanger shown includes multiple plate channels and multiple flow paths. Each flow path corresponds one-to-one with a plate channel. It should be understood that a plate channel is the space between two adjacent corrugated metal plates in the plate heat exchanger, while a flow path is a path for the refrigerant to flow, consisting of the inlet manifold, the corresponding plate channel, and the outlet manifold.

[0064] The method may include the following steps S101-S103.

[0065] S101, obtain the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path.

[0066] In this step, based on the inlet conditions of the fluids on both sides and the assumed uniform refrigerant flow distribution, the internal pressure drop and heat transfer value of each plate channel in the plate heat exchanger are calculated. Then, based on the heat transfer value of each plate channel, the temperature value and local heat transfer coefficient of each plate channel are obtained, thereby determining the friction temperature value and local heat transfer coefficient of the fluids on both sides (refrigerant side and hot side). At the same time, based on the internal pressure drop value of each plate channel, the total pressure drop value of each flow path between the inlet and outlet of the plate heat exchanger is further determined.

[0067] S102, if the total pressure drop values ​​of each flow path are different, the gas refrigerant flow rate of each plate channel is adjusted using the total pressure drop values ​​of each flow path, and the process returns to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path; otherwise, the temperature distribution of the outer wall of the plate heat exchanger is obtained based on the temperature value and local heat transfer coefficient of each plate channel.

[0068] In this step, it is determined whether the total pressure drop value of all flow paths is the same. If the total pressure drop values ​​of all flow paths are different, it indicates that the flow rate distribution of the gaseous refrigerant in each plate channel is uneven. At this time, the flow rate value of the gaseous refrigerant in each plate channel is adjusted using the total pressure drop value of each flow path, and the process returns to the previous step to recalculate the internal pressure drop value and heat transfer value of each plate channel, as well as the total pressure drop value of each flow path. If the total pressure drop value of all flow paths is the same, it indicates that the flow rate distribution of the gaseous refrigerant in each plate channel is uniform. At this time, the gaseous refrigerant distribution process of each plate channel ends, and the temperature distribution of the outer wall of the plate heat exchanger is calculated based on the friction temperature value and local heat transfer coefficient of the fluid on both sides (refrigerant side and hot side). It is worth noting that this temperature distribution is the expected temperature distribution of the outer wall of the plate heat exchanger, which is used in subsequent steps to adjust the flow rate of the liquid refrigerant in the plate heat exchanger in conjunction with the actual temperature distribution of the outer wall of the plate heat exchanger.

[0069] S103, if the temperature distribution of the outer wall surface is inconsistent with the infrared image of the side wall surface of the plate heat exchanger, the liquid refrigerant flow rate of each plate channel is adjusted using the temperature distribution of the outer wall surface and the infrared image of the side wall surface, and the process returns to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path; otherwise, the gas refrigerant flow rate and liquid refrigerant flow rate of each plate channel are output.

[0070] In this step, firstly, real-time infrared measurement is performed on the plate heat exchanger to obtain an infrared image of the plate heat exchanger's sidewall. The temperature distribution indicated by this infrared image is the actual temperature distribution of the outer wall of the plate heat exchanger. Then, the outer wall temperature distribution obtained in the previous step is compared with the real-time measured infrared image of the sidewall to determine if they are consistent. If they are inconsistent, it indicates that the flow distribution of the liquid refrigerant in each plate channel is uneven. At this point, the liquid refrigerant flow rate of each plate channel is adjusted using the outer wall temperature distribution and the infrared image of the sidewall, and the process returns to the first step to recalculate the internal pressure drop and heat transfer value of each plate channel, as well as the total pressure drop value of each flow path. If they are consistent, it indicates that the flow distribution of the liquid refrigerant in each plate channel is uniform. At this point, the adjustment ends, and the gaseous refrigerant flow rate and liquid refrigerant flow rate of each plate channel are output.

[0071] In some implementations, refer to Figure 4 and Figure 5 , Figure 4 and Figure 5 The red areas represent the hot side plate channels, and the blue areas represent the refrigerant side plate channels. Indicates the total flow rate of the refrigerant. This indicates the total flow rate of the hot-side fluid. Indicates the total dryness of the refrigerant inlet. This indicates the flow rate of each hot side plate channel. Indicates the flow rate of each refrigerant side plate channel. Indicates the inlet dryness of each refrigerant side plate channel. Indicates the total number of units. This indicates the total number of plate channels. In step S101 above, the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path, are obtained, including the following steps S1011-S1015.

[0072] S1011 divides each plate channel into multiple units along the length of the plate heat exchanger.

[0073] It should be noted that multiple plate channels include multiple hot-side plate channels and multiple refrigerant side plate channels, such as... Figure 4 and Figure 5 As shown, multiple hot-side plate channels and multiple refrigerant-side plate channels are alternately arranged, that is, starting from the inlet or outlet, from left to right, they are the first hot-side plate channel, the first refrigerant-side plate channel, the second hot-side plate channel, the second refrigerant-side plate channel, and so on. Each hot-side plate channel includes multiple hot-side units connected sequentially along the flow direction of the hot-side fluid in the plate heat exchanger, and each refrigerant-side plate channel includes multiple refrigerant-side units connected sequentially along the flow direction of the gaseous refrigerant.

[0074] In this step, within the plate heat exchanger, the fluid in each plate channel exchanges heat with the fluids in its two adjacent plate channels. Therefore, the temperature distributions of the fluid on the refrigerant side and the fluid on the hot side influence each other, necessitating iterative calculations. In the iterative calculations, firstly, based on the finite volume method, each plate channel is divided along the length of the plate heat exchanger into... The heat exchanger consists of several units. The plate channels can be divided into two types: hot-side plate channels and refrigerant-side plate channels. Accordingly, after dividing the heat exchanger into units, each hot-side plate channel includes multiple hot-side units connected sequentially along the flow direction of the hot-side fluid, and each refrigerant-side plate channel includes multiple refrigerant-side units connected sequentially along the flow direction of the gaseous refrigerant. This step transforms the continuous temperature distribution into discrete unit parameter calculations, treating the fluid temperature, flow rate, and other parameters within each unit as uniform, thus simplifying the numerical solution.

[0075] S1012, set the inlet temperature value of each hot-side unit to the preset temperature value.

[0076] In this step, the inlet temperature of all hot-side units in all hot-side plate channels is set to the same preset temperature value. This preset temperature value can be flexibly set according to actual conditions. This step is essentially an initialization of the hot-side units, thereby ensuring the accuracy of subsequent processing steps.

[0077] S1013, for each refrigerant side plate channel, obtain the heat exchange value of each refrigerant side unit and its two adjacent heat side units in the current refrigerant side plate channel, as well as the outlet temperature value of each refrigerant side unit in the current refrigerant side plate channel.

[0078] In this step, for each refrigerant side plate channel, along the flow direction of the gaseous refrigerant (i.e., from bottom to top), the heat exchange value of each refrigerant side unit in the current refrigerant side plate channel and its two adjacent heat side units, as well as the outlet temperature value of each refrigerant side unit in the current refrigerant side plate channel, are calculated sequentially.

[0079] Specifically, any refrigerant-side unit in the current refrigerant side plate channel is defined as the target refrigerant-side unit, such as... Figure 4 and Figure 5 As shown, the two adjacent refrigerant side plate channels are both hot side plate channels. Therefore, the total heat transfer (i.e., heat exchange value) of the target refrigerant side unit is the sum of the heat transfer from the hot side units of the two adjacent hot side plate channels. The law of conservation of energy needs to be considered in the calculation, as shown in the following formula (1):

[0080] (1);

[0081] In equation (1), Indicates the board channel number. The number of the unit representing the board channel. Indicates the first Total refrigerant flow rate of each refrigerant side plate channel; Indicates the first The first refrigerant side plate channel The outlet specific enthalpy of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The inlet specific enthalpy of each refrigerant-side unit; Indicates from the first The first refrigerant side plate channel The left side heat side unit of the refrigerant side unit to the first The first refrigerant side plate channel Heat transfer of each refrigerant-side unit; Indicates from the first The first refrigerant side plate channel The right side heat-side unit of the refrigerant-side unit to the first The first refrigerant side plate channel The heat transfer of each refrigerant-side unit. It should be understood that heat transfer is the heat exchange value.

[0082] Based on the total heat transfer coefficient, average logarithmic temperature difference, and heat transfer area of ​​the target refrigerant side unit and its two adjacent heat-side units, the heat transfer value between the target refrigerant side unit and its two adjacent heat-side units is obtained. That is, the heat transfer between the heat-side units on the left and right sides adjacent to the target refrigerant side unit is calculated based on the logarithmic average temperature difference, as shown in the following formula (2):

[0083] ,

[0084] (2);

[0085] In equation (2), This represents the heat exchange area between the target refrigerant-side unit and its two adjacent heat-side units. Indicates the first The first refrigerant side plate channel The total heat transfer coefficient of the refrigerant-side unit and its adjacent left-side heat-side unit; Indicates the first The first refrigerant side plate channel The total heat transfer coefficient of the refrigerant-side unit and its adjacent right-side heat-side unit; Indicates the first The first refrigerant side plate channel The average logarithmic temperature difference between a refrigerant-side unit and its adjacent left-side heat-side unit; Indicates the first The first refrigerant side plate channel The average logarithmic temperature difference between a refrigerant-side unit and its adjacent right-side heat-side unit.

[0086] The overall heat transfer coefficient can satisfy the following formula (3):

[0087] ,

[0088] (3);

[0089] In equation (3), Indicates the first The first refrigerant side plate channel The heat transfer coefficient of adjacent heat-side units of a refrigerant-side unit; Indicates the first The first refrigerant side plate channel The heat transfer coefficient of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The heat transfer coefficient of an adjacent heat-side unit of a refrigerant-side unit. This heat transfer coefficient can be calculated by selecting the corresponding correlation formula based on the panel type and fluid state. The correlation formula is existing technology and will not be elaborated further.

[0090] The mean logarithmic temperature difference can satisfy the following formulas (4)-(5):

[0091] (4);

[0092] In equation (4), Indicates the first The first refrigerant side plate channel The inlet temperature values ​​of adjacent hot-side units of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The outlet temperature value of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The outlet temperature values ​​of adjacent hot-side units of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The inlet temperature value of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The outlet temperature value of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The outlet temperature value of the adjacent hot-side unit of each refrigerant-side unit.

[0093] (5);

[0094] In equation (5), Indicates the first The first refrigerant side plate channel The inlet temperature values ​​of adjacent hot-side units of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The outlet temperature values ​​of adjacent hot-side units of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The outlet temperature value of the adjacent hot-side unit of each refrigerant-side unit.

[0095] By combining the above formulas (1)-(5), the heat transfer between the target refrigerant-side unit and its adjacent left and right hot-side units, as well as the outlet specific enthalpy, can be solved. The outlet temperature of the target refrigerant-side unit can be further obtained through the property table (enthalpy-temperature correspondence). Thus, through the above process, the heat transfer values ​​between each refrigerant-side unit in all refrigerant side plate channels and its two adjacent hot-side units, as well as the outlet temperature values ​​of each refrigerant-side unit in all refrigerant side plate channels, can be obtained.

[0096] S1014, For each hot side plate channel, update the outlet temperature value of each hot side unit in the current hot side plate channel according to the heat exchange value between each hot side unit in the current hot side plate channel and its two adjacent refrigerant side units.

[0097] In this step, for each hot side plate channel, along the hot side fluid flow direction (from top to bottom), starting from the first hot side unit at the top, the outlet temperature value of each hot side unit in the current hot side plate channel is updated according to the heat exchange value between each hot side unit in the current hot side plate channel and its two adjacent refrigerant side units. Specifically, any hot side unit in the current hot side plate channel is defined as the target hot side unit. Based on the inlet temperature value of the target hot side unit, the gas refrigerant flow rate value of the current hot side plate channel, and the heat exchange value between the target hot side unit and its two adjacent refrigerant side units, combined with the specific heat capacity of the hot side fluid, the outlet temperature value of the target hot side unit is obtained as shown in the following formula (6):

[0098] (6);

[0099] In equation (6), Indicates the first The first refrigerant side plate channel The outlet temperature value of the adjacent right-side hot-side unit of each refrigerant-side unit; Indicates the first The first refrigerant side plate channel The inlet temperature value of the adjacent right-side heat-side unit of a refrigerant-side unit; Indicates the first The first refrigerant side plate channel The right side heat-side unit of the refrigerant-side unit to the first The first refrigerant side plate channel Heat transfer of each refrigerant-side unit; This represents the specific heat capacity of the hot-side fluid. It should be understood that in the current hot-side plate channel, the outlet temperature of the target hot-side unit will be used as the inlet temperature of the next hot-side unit, and the order of the hot-side temperatures follows the direction of hot-side fluid flow (from top to bottom). Thus, the outlet temperature of each hot-side unit in all hot-side plate channels can be obtained through the above process.

[0100] S1015, if the temperature distribution of each plate channel does not meet the preset conditions, return to the step of obtaining the heat transfer value of each refrigerant side unit and its two adjacent hot side units in the current refrigerant side plate channel, and the outlet temperature value of each refrigerant side unit in the current refrigerant side plate channel for each refrigerant side plate channel; otherwise, output the outlet temperature value of each unit in each plate channel as the temperature value of each plate channel, and determine the local heat transfer coefficient of each plate channel based on the heat transfer value of each refrigerant side unit and its two adjacent hot side units in each refrigerant side plate channel.

[0101] In this step, it is determined whether the temperature distribution of each plate channel meets the preset conditions. The preset conditions are used to indicate that the temperature curves (i.e., temperature distributions) of each refrigerant side plate channel and each hot side plate channel are stable. For example, the temperature change of all units in each plate channel is less than the preset change threshold in two adjacent iterations, or the relative temperature change rate of all units in each plate channel is less than the preset change rate threshold in two adjacent iterations, but not limited to these. If not, it means that the temperature distribution of each plate channel is not yet stable. At this time, it will return to the above step S1013 for iterative calculation. If yes, it means that the temperature distribution of each plate channel is stable. At this time, the outlet temperature value of each unit in each plate channel will be output as the temperature value of each plate channel. At the same time, the heat transfer value of each refrigerant side unit in each refrigerant side plate channel and its two adjacent hot side units will be used, combined with the above formulas (2)-(3) to obtain the heat transfer coefficient of each unit in each plate channel, thereby obtaining the local heat transfer coefficient of each plate channel.

[0102] Therefore, this embodiment solves the bidirectional heat transfer problem of plate heat exchangers through iterative coupling. The core is to use the finite volume method to discretize the refrigerant side and the temperature on the heat side, and then alternately update the enthalpy / temperature on the refrigerant side and the temperature on the heat side, eventually converging to a stable solution. The formula system provided by this embodiment covers key aspects such as energy conservation, heat transfer coefficient, and temperature difference calculation, which can effectively improve the accuracy of the temperature value and local heat transfer coefficient of each plate channel.

[0103] In some implementations, refer to Figure 6 In step S101 above, obtaining the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path, includes the following step S1016:

[0104] S1016. Based on the total pressure drop of the inlet manifold corresponding to the target flow path, the total pressure drop of the outlet manifold corresponding to the target flow path, and the internal pressure drop of the plate channel corresponding to the target flow path, the total pressure drop of the target flow path is obtained; wherein, the target flow path is any flow path; the inlet manifold corresponding to the target flow path is the inlet manifold section from the inlet of the plate heat exchanger to the inlet of the plate channel corresponding to the target flow path; the outlet manifold corresponding to the target flow path is the outlet manifold section from the outlet of the plate channel corresponding to the target flow path to the outlet of the plate heat exchanger.

[0105] In this embodiment, by adjusting the quantification of the gaseous refrigerant flow distribution, the total pressure drop of all flow paths from the inlet of the plate heat exchanger, through the inlet manifold, plate channel, and outlet manifold, to the outlet of the plate heat exchanger is equal, thereby achieving quantification of the gaseous refrigerant flow distribution. For example... Figure 6 As shown, for each flow path, the total pressure drop is divided into three parts: the pressure drop value in the inlet manifold, the pressure drop value in the outlet manifold, and the internal pressure drop value in the plate channel corresponding to the flow path.

[0106] Specifically, if any flow path is defined as the target flow path, then:

[0107] Based on the frictional pressure drop value of the inlet manifold corresponding to the target flow path, and combined with either the acceleration pressure drop value or the deceleration pressure drop value of the inlet manifold corresponding to the target flow path, the total pressure drop value of the inlet manifold corresponding to the target flow path is obtained. Similarly, based on the frictional pressure drop value of the outlet manifold corresponding to the target flow path, and combined with either the acceleration pressure drop value or the deceleration pressure drop value of the outlet manifold corresponding to the target flow path, the total pressure drop value of the outlet manifold corresponding to the target flow path is obtained.

[0108] In this process, the first The flow path (i.e. the first) The total pressure drop of the inlet manifold corresponding to the flow path where each plate channel is located can be expressed as the sum of the pressure drops of each upstream inlet manifold section, as shown in the following formula (7):

[0109] (7);

[0110] No. The total pressure drop of the outlet manifold corresponding to each flow path can be expressed as the sum of the pressure drops of each downstream outlet manifold section, as shown in the following formula (8):

[0111] (8);

[0112] In equations (7)-(8), Indicates the first The inlet manifold corresponding to each channel ( ) or export manifold ( The pressure drop of segment ) can be expressed as the following formula (9):

[0113] (9);

[0114] In equation (9), Indicates the first The inlet manifold corresponding to each flow path ( ) or export manifold ( The frictional pressure drop value; Indicates the first The inlet manifold corresponding to each flow path ( ) or export manifold ( The acceleration pressure drop value () ) or deceleration pressure drop value ( ).

[0115] Furthermore, based on the local pressure drop between the inlet manifold corresponding to the target flow path and the plate channel corresponding to the target flow path, and the local pressure drop between the outlet manifold corresponding to the target flow path and the plate channel corresponding to the target flow path, combined with the frictional pressure drop, gravity pressure drop, and acceleration pressure drop of the plate channel corresponding to the target flow path, the internal pressure drop of the plate channel corresponding to the target flow path is obtained as shown in the following formula (10):

[0116] (10);

[0117] In equation (10), Indicates the first The internal pressure drop value of the plate channel corresponding to each flow path; Indicates the first The inlet manifold corresponding to the flow path and the... Local pressure drop values ​​between the plate channels corresponding to each flow path; Indicates the first The outlet manifold corresponding to the flow path and the first Local pressure drop values ​​between the plate channels corresponding to each flow path; Indicates the first The frictional pressure drop value corresponding to each flow path; Indicates the first The gravity pressure drop value corresponding to each flow path; Indicates the first The acceleration pressure drop value corresponding to each flow path.

[0118] It should be noted that, depending on the plate type and manifold design, as well as the difference in refrigerant state (two-phase or single-phase), different existing pressure drop correlation formulas are selected to calculate the above pressure drop components, which will not be elaborated further.

[0119] In summary, the total pressure drop of the target flow path satisfies the following formula (11):

[0120] (11);

[0121] In equation (11), Indicates the first The total pressure drop value of each flow path.

[0122] Therefore, this embodiment, by fully considering the pressure drop factors of the inlet manifold section, outlet manifold section, and plate channel associated with the flow path, realizes the calculation and processing of the total pressure drop value of the flow path, thus effectively improving the accuracy of the total pressure drop value of the flow path.

[0123] In some embodiments, step S102 above, adjusting the gas refrigerant flow rate of each plate channel using the total pressure drop value of each flow path, includes the following steps S1021-S1022:

[0124] S1021, Obtain the average total pressure drop value of all flow paths as the average pressure drop value of the flow paths;

[0125] S1022, Based on the average pressure drop of the flow path and the total pressure drop of each flow path, the gas refrigerant flow rate of each plate channel is adjusted to obtain the adjusted gas refrigerant flow rate of each plate channel as the new gas refrigerant flow rate of each plate channel.

[0126] In this embodiment, when the total pressure drop values ​​of all flow paths are different, it is necessary to adjust the distribution of gaseous refrigerant in each plate channel and return to step S101 above until the total pressure drop values ​​of all flow paths are the same. The adjustment method is as follows: First, obtain the average value of the total pressure drop values ​​of all flow paths as the average pressure drop value of the flow path; then, introduce a scaling factor, combine the average pressure drop value of the flow path and the total pressure drop value of each flow path, and adjust the gaseous refrigerant flow rate value of each plate channel as shown in the following formula (12):

[0127] (12);

[0128] In equation (12), Indicates the first The adjusted refrigerant flow rate value for each plate channel; Indicates the first The refrigerant flow rate value of each plate channel before adjustment; This represents the scaling factor, which is a preset value. Indicates the first The total pressure drop of the flow path where each plate channel is located; This represents the average pressure drop across the flow path. In this formula, when the total pressure drop across a flow path exceeds the average pressure drop, the refrigerant flow rate in the plate channel of that flow path is reduced; conversely, it is increased. It should be understood that the adjusted refrigerant flow rate in the plate channel alters the aforementioned pressure drop components through a correlation formula, thereby affecting the total pressure drop across all flow paths, thus creating a cycle. This method allows for precise adjustment of the refrigerant flow rate in each plate channel.

[0129] In some embodiments, step S102 above, obtaining the temperature distribution of the outer wall of the plate heat exchanger based on the temperature value of each plate channel and the local heat transfer coefficient, includes the following steps S1023-S1026.

[0130] S1023. Based on the temperature values ​​of each plate channel, determine the hot-side fluid temperature field of the plate heat exchanger, and based on the local heat transfer coefficient of each plate channel, determine the heat transfer coefficient field of the plate heat exchanger.

[0131] In this step, the temperature of the outer wall of the plate heat exchanger is determined by the temperature and heat transfer coefficient distribution of the refrigerant on its inner side and the fluid on the hot side. Therefore, when determining the temperature distribution of the outer wall, the temperature field of the fluid on the hot side of the plate heat exchanger is first constructed using the temperature values ​​of each plate channel obtained above. At the same time, the heat transfer coefficient field of the plate heat exchanger is constructed based on the local heat transfer coefficient of each plate channel.

[0132] S1024, based on the finite difference method, establishes a three-dimensional computational mesh for the sidewall of the plate heat exchanger, and maps the hot-side fluid temperature field and heat transfer coefficient field to the three-dimensional computational mesh.

[0133] In this step, a three-dimensional computational mesh for the sidewall of the plate heat exchanger is established based on the finite difference method. Since the temperature field and heat transfer coefficient field of the input hot-side fluid are not uniformly distributed, the input data on the coarse mesh needs to be mapped onto a refined three-dimensional computational mesh.

[0134] S1025 uses a three-dimensional computational mesh to iteratively solve the three-dimensional steady-state heat conduction differential equation without internal heat source and its boundary conditions of the plate heat exchanger, and obtains the overall temperature distribution of the side wall of the plate heat exchanger.

[0135] In this step, in order to accurately obtain the temperature distribution on the outer wall of the heat exchanger, it is necessary to consider the three-dimensional heat conduction effect inside the wall. The governing equation is the three-dimensional steady-state heat conduction differential equation without internal heat source (Laplace equation), as shown in the following formula (13):

[0136] (13);

[0137] In equation (13), Indicates the temperature value; Represents the x-coordinate in three-dimensional space; Represents the vertical coordinate in three-dimensional space.

[0138] Its boundary conditions are as follows: the bottom surface (z=0) corresponds to the inner wall surface in contact with the fluid, which is a third type of boundary condition, as shown in the following formula (14):

[0139] (14);

[0140] In equation (14), Indicates thermal conductivity; Indicates the coordinates of the point. The three-dimensional temperature distribution; Indicates the coordinates of the point. The fluid temperature (including refrigerant and hot fluid). Indicates the coordinates of the point. The fluid heat transfer coefficients (including those of the refrigerant and the hot fluid) are both spatially distributed variables. Apart from these, the remaining boundary conditions are adiabatic.

[0141] After obtaining the differential equations and their boundary conditions, the central difference scheme is used to discretize the governing equations inside the wall and at the adiabatic boundary, while "ghost nodes" are introduced at the fluid contact surface (z=0) to handle the third type of boundary conditions mentioned above.

[0142] In order to improve computational efficiency and numerical stability, the Red-Black Gauss-Seidel iterative method combined with the super-relaxation (SOR) technique was adopted in the solution process. The nodes in the computational domain were marked as "red" and "black". The temperature values ​​of the two types of nodes were updated alternately during the iteration until the temperature residual of the whole field met the convergence criterion. This process is the existing technology. In short, for any node inside the wall, its discrete control equation is constructed based on the three-dimensional steady-state heat conduction differential equation. After introducing the super-relaxation factor, the update formula of the red-black iteration is as follows (15):

[0143] (15);

[0144] In equation (15), Indicates in , and Temperature node index in the direction; This represents the temperature distribution after iterative updates; This represents the temperature distribution before the iterative update; This represents the over-relaxation factor, which is a preset value. These are the grid coefficients for the three directions, , , , Indicates the thermal conductivity of the wall. , and Indicates the spatial step size.

[0145] On the fluid contact side at z=0, the heat flux density is determined by convective heat transfer. Using the element-center ghost node method, its boundary temperature... With internal nodes and fluid temperature The relationship is shown in the following formula (16):

[0146] (16);

[0147] Among them, coefficient It is determined by the Bi number, as shown in the following formula (17):

[0148] (17).

[0149] The overall temperature distribution on the sidewall of the plate heat exchanger can be obtained by numerical solution.

[0150] S1026, the two-dimensional temperature distribution of the outer plane is extracted from the overall temperature distribution of the sidewall as the temperature distribution of the outer wall.

[0151] In this step, after obtaining the overall temperature distribution of the sidewalls of the plate heat exchanger, the temperature of the top surface (i.e., the outer sidewall) is read. The two-dimensional temperature distribution can be obtained to get the temperature distribution of the outer wall surface, as shown in the following formula (18), and then it can be resampled back to the original input grid center position by bilinear interpolation:

[0152] (18).

[0153] Therefore, this implementation method can effectively improve the accuracy and calculation efficiency of the temperature distribution on the outer side wall.

[0154] In some embodiments, the above method further includes:

[0155] The error value between the temperature distribution on the outer wall and the infrared image of the outer wall is used as the target error value;

[0156] If the target error value is less than the preset error threshold, the temperature distribution of the outer wall surface is determined to be consistent with the infrared image of the side wall surface; otherwise, the temperature distribution of the outer wall surface is determined to be inconsistent with the infrared image of the side wall surface.

[0157] In this embodiment, to determine whether the actual temperature distribution and the desired temperature distribution on the outer wall of the plate heat exchanger are consistent, the error value between the outer wall temperature distribution and the infrared image of the side wall is first obtained as a target error value. This target error value measures the difference between the actual temperature distribution and the desired temperature distribution on the outer wall of the plate heat exchanger. The smaller the target error value, the higher the degree of matching. Then, it is determined whether the target error value is less than a preset error threshold. If so, it means that the difference between the two is within an acceptable range, and the outer wall temperature distribution and the infrared image of the side wall are determined to be consistent. If not, it means that the difference between the two is not within an acceptable range, and the outer wall temperature distribution and the infrared image of the side wall are determined to be inconsistent. Here, the difference between the actual temperature distribution and the desired temperature distribution is used to directly determine whether the temperature distributions of the two data are consistent, thereby determining whether the flow rate of the liquid refrigerant in each plate channel needs to be adjusted. This ensures the accuracy of the pre-judgment of liquid refrigerant flow rate adjustment.

[0158] Optionally, the type of the target error value can be flexibly set according to the actual situation. For example, the target error value can be the mean squared error (MSE), as shown in the following formula (19):

[0159] (19);

[0160] In equation (19), Index of temperature nodes representing the temperature distribution on the outer wall surface The value; Index representing the temperature node of the infrared image of the sidewall The value; This indicates the total number of temperature nodes on the outer wall surface.

[0161] In some embodiments, step S103 above, adjusting the liquid refrigerant flow rate of each plate channel using the temperature distribution of the outer wall surface and the infrared image of the side wall surface, includes the following steps S1031-S1032:

[0162] S1031, based on the automatic differentiation method, obtain the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel; wherein, the target error value is the error value between the temperature distribution of the outer wall and the infrared image of the side wall.

[0163] In this step, the temperature distribution on the outer wall surface calculated using a simulation model is presented. Temperature distribution compared with the measured infrared images of the side wall surface The error value between the two (i.e., the target error value) serves as a measure of the degree of matching between them. The smaller the target error value, the higher the degree of matching. In order to achieve the matching of the outer wall temperature, it is necessary to adjust the liquid refrigerant flow distribution quantization in the simulation model in the direction of reducing the target error value. Therefore, it is necessary to calculate the derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel, as shown in the following formula (20):

[0164] (20);

[0165] In equation (20), Indicates the target error value; Indicates the first The liquid refrigerant flow rate of each plate channel.

[0166] This step uses automatic differentiation to achieve this goal. Automatic differentiation is a technique in which computer programs automatically calculate the derivative of a function by decomposing the program into a sequence of basic operations and applying the chain rule to combine the differential values. Before applying automatic differentiation to the plate heat exchanger performance simulation model proposed in this step, two parts of the model need to be rewritten:

[0167] 1) All physical properties are explicitly fitted using high-order polynomials, without using external functions / programs (such as refprop, etc.).

[0168] 2) All nonlinear solvers based on "residuals" need to be rewritten to solve for a fixed number of iterations. In order to ensure the accuracy of the solution, the solver based on "residuals" is run first under the same initial conditions to obtain the required number of iterations. Then the solver is changed to a fixed number of iterations and automatic differentiation is performed.

[0169] The partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel can be obtained by means of the above formula (20).

[0170] S1032, based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel, adjust the liquid refrigerant flow rate of each plate channel to obtain the adjusted liquid refrigerant flow rate of each plate channel as the new liquid refrigerant flow rate of each plate channel.

[0171] In this step, the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel is used as a benchmark to adjust the liquid refrigerant flow rate of each plate channel. The adjusted liquid refrigerant flow rate of each plate channel is then used as the new liquid refrigerant flow rate of each plate channel, thereby realizing the quantitative processing of liquid refrigerant flow distribution in each plate channel.

[0172] In some embodiments, in step S1032 above, the liquid refrigerant flow rate of each plate channel is adjusted according to the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel, and the adjusted liquid refrigerant flow rate of each plate channel is obtained as the new liquid refrigerant flow rate of each plate channel, including the following steps S01-S04.

[0173] S01, obtain the average value of the liquid refrigerant flow rate of all plate channels as the average liquid refrigerant flow rate.

[0174] In this step, the liquid refrigerant flow rate values ​​of all plate channels are averaged to obtain the average liquid refrigerant flow rate value, which indicates the average level of liquid refrigerant flow rate values ​​in all plate channels.

[0175] S02, based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel and the average liquid refrigerant flow rate, the adaptive step size is obtained.

[0176] In this step, in order to ensure the stability of the iteration and avoid numerical oscillation caused by excessive flow rate changes, the adaptive step size is calculated based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel and the average liquid refrigerant flow rate, as shown in the following formula (21):

[0177] (twenty one);

[0178] In equation (21), Indicates adaptive step size; This represents the step scaling factor, which is a preset value. This represents the average flow rate of the liquid refrigerant. This represents the partial derivative of the target error value with respect to the liquid refrigerant flow rate in each plate channel. Indicates the total number of board channels. This represents the L2 norm of the gradient vector.

[0179] S03, based on the adaptive step size and the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel, unconstrained gradient descent is performed on the liquid refrigerant flow rate of each plate channel to obtain the intermediate variable vector of each plate channel.

[0180] In this step, during the unconstrained gradient descent process, for each plate channel, based on the calculated adaptive step size, the liquid refrigerant flow rate value of the current plate channel is initially updated along the opposite direction of the gradient, i.e., unconstrained flow rate update, thereby obtaining the intermediate variable vector of the current plate channel. By traversing all plate channels, the intermediate variable vector of all plate channels can be obtained, as shown in the following formula (22):

[0181] (twenty two);

[0182] In equation (22), Indicates the first The intermediate variable vector of each board channel; Indicates the first The liquid refrigerant flow rate value before the update of each plate channel; Indicates the target error value with respect to the first... The partial derivative of the liquid refrigerant flow rate value for each plate channel. Although the intermediate variable vector obtained at this time reduces the target error value, it does not follow the conservation condition of constant total flow rate. Therefore, it is necessary to redistribute and correct the liquid refrigerant flow rate distribution in the next step.

[0183] S04. Perform simplex projection on the intermediate variable vectors of each plate channel to obtain the adjusted liquid refrigerant flow rate value of each plate channel as the new liquid refrigerant flow rate value of each plate channel.

[0184] In this step, to satisfy the total flow conservation constraint and the non-negativity constraint, for each plate channel, the intermediate variable vector of the current plate channel is processed by simplex projection. The aim is to use the Euclidean projection algorithm to map the intermediate variable vector back into the feasible region, thereby obtaining the adjusted liquid refrigerant flow value of the current plate channel as the new liquid refrigerant flow value of the current plate channel. By traversing all plate channels, the new liquid refrigerant flow values ​​of all plate channels can be obtained, thereby realizing the quantitative processing of liquid refrigerant flow distribution for each plate channel.

[0185] In some embodiments, step S04 above, performing simplex projection processing on the intermediate variable vectors of each plate channel to obtain the adjusted liquid refrigerant flow rate value of each plate channel as the new liquid refrigerant flow rate value of each plate channel, includes:

[0186] The intermediate variable vectors of each plate channel are sorted and their positions are found to obtain the optimal truncation position;

[0187] Based on the optimal cutoff position and the total flow rate of the liquid refrigerant, the Lagrange multipliers are obtained;

[0188] Based on the Lagrange multipliers and the intermediate variable vectors of each plate channel, the adjusted liquid refrigerant flow rate value of each plate channel is obtained as the new liquid refrigerant flow rate value of each plate channel.

[0189] In this embodiment, the simplex projection process for each plate channel is equivalent to solving the quadratic programming problem shown in the following formula (23):

[0190] (twenty three);

[0191] In equation (23), Indicates the first The liquid refrigerant flow rate value after adjustment of each plate channel; This represents the total flow rate of liquid refrigerant in all plate channels. The specific logic for solving this problem is as follows:

[0192] First, sort the intermediate variable vectors of each board channel in descending order to obtain the sorted intermediate variable vectors of each board channel. Then, integrate these vectors into a sorted vector and find the optimal cutoff position so that the position satisfies the following formula (24):

[0193] (twenty four);

[0194] In equation (24), Indicates the optimal cutoff position; Represents the sorting vector The Each element.

[0195] Then, the Lagrange multipliers are calculated further, as shown in the following formula (25):

[0196] (25);

[0197] In equation (25), It represents the Lagrange multiplier.

[0198] Finally, for each plate channel, the liquid refrigerant flow rate value of the current plate channel is redistributed and updated according to the Lagrange multiplier, and the adjusted liquid refrigerant flow rate value of the current plate channel is obtained as the new liquid refrigerant flow rate value of the current plate channel. By traversing all plate channels, the new liquid refrigerant flow rate value of all plate channels can be obtained, as shown in the following formula (26):

[0199] (26).

[0200] In this way, the new flow distribution not only strictly satisfies the physical constraint of constant total flow, but also achieves a decrease in the objective function.

[0201] The following will use an application scenario as an example to illustrate the principle of the embodiments of this application. (Refer to...) Figure 7 The process of adjusting the flow rate of the gas-liquid two-phase refrigerant in each plate channel of the plate heat exchanger in this application scenario is as follows:

[0202] 1) Input the total refrigerant flow rate, refrigerant inlet dryness, refrigerant saturation temperature, hot-side fluid flow rate, and hot-side fluid inlet temperature. Assuming that the gas-liquid two-phase refrigerant flow rate is uniformly distributed, based on the inlet state of the fluids on both sides and combined with the above formulas (1)-(11), calculate the internal pressure drop and heat transfer value of each plate channel in the plate heat exchanger, thereby obtaining the friction temperature and local heat transfer coefficient of the fluids on both sides.

[0203] 2) Calculate the total pressure drop of each flow path in the plate heat exchanger and determine whether the total pressure drop of all flow paths is the same. If they are not the same, then for each plate channel, adjust the gas refrigerant flow rate of the current plate channel according to the total pressure drop of the current plate channel and the above formula (12), and return to step 1) until the total pressure drop of all flow paths is the same.

[0204] 3) Based on the friction temperature and local heat transfer coefficient of the fluid on both sides, and combined with the above formulas (13)-(18), the temperature distribution of the outer wall of the plate heat exchanger is calculated. It is compared with the infrared image of the side wall of the plate heat exchanger measured in practice to obtain the mean square error between the two temperature distributions, as shown in the above formula (19), which is the mean square of the temperature difference between the corresponding nodes on the wall.

[0205] 4) Determine whether the mean square error is less than the preset error threshold. If yes, it is assumed that the temperature distribution of the two walls is consistent, and the gas refrigerant flow rate and liquid refrigerant flow rate of all plate channels are output. If no, proceed to the next step.

[0206] 5) Based on the automatic differentiation method, calculate the partial derivative of the mean square error with respect to the liquid refrigerant flow rate of each plate channel, as shown in the above formula (20). Based on this partial derivative, adjust the liquid refrigerant flow rate of each plate channel in the direction of reducing the mean square error, as shown in the above formulas (21)-(26), and return to step 1). Repeat this process until the temperature distribution of the two walls is consistent, thus completing the quantization.

[0207] Using the method of this application embodiment, the refrigerant inlet dryness fraction is between 0.1 and 0.3, and the average refrigerant plate channel mass flux is between 7.5 and 12.5. The flow distribution was quantified at nine operating points of the heat exchanger. Since there is currently no direct and accurate method for quantifying the refrigerant gas-liquid two-phase flow distribution within a plate heat exchanger, and considering that the quantification of refrigerant gas-liquid two-phase flow distribution significantly affects heat exchanger performance, the measured heat transfer rate of the heat exchanger was compared with the heat transfer rate calculated during the quantification process. Figure 8 As shown, the relative error is within 3%. Figure 9 The temperature distribution on the outer wall obtained from the quantitative simulation was compared with the infrared measured temperature distribution, and the two are in excellent agreement. This demonstrates that the embodiments of this application can improve the quantitative accuracy of the flow distribution of the gas-liquid two-phase refrigerant within the plate heat exchanger.

[0208] Furthermore, this application provides a plate heat exchanger refrigerant flow distribution quantification device, characterized in that the plate heat exchanger includes multiple plate channels and multiple flow paths, with each flow path corresponding to one of the multiple plate channels. The plate channel is the space between two adjacent corrugated metal plates in the plate heat exchanger, and the flow path consists of the inlet manifold of the plate heat exchanger, the plate channel corresponding to the flow path, and the outlet manifold of the plate heat exchanger. The device includes:

[0209] The acquisition module is used to acquire the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path;

[0210] The first processing module is used to adjust the gas refrigerant flow rate of each plate channel by using the total pressure drop value of each flow channel if the total pressure drop value of each flow channel is different, and return to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow channel; otherwise, it obtains the temperature distribution of the outer wall of the plate heat exchanger based on the temperature value and local heat transfer coefficient of each plate channel.

[0211] The second processing module is used to adjust the liquid refrigerant flow rate of each plate channel by using the temperature distribution of the outer wall and the infrared image of the side wall of the plate heat exchanger if the temperature distribution of the outer wall and the infrared image of the side wall are inconsistent. It also triggers the acquisition module to obtain the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path. Otherwise, it outputs the gas refrigerant flow rate and liquid refrigerant flow rate of each plate channel.

[0212] The content of the above method embodiments is applicable to the device embodiments. The specific functions implemented by the device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0213] In summary, this embodiment of the application calculates the gas-liquid two-phase refrigerant flow rate in each plate channel by matching the infrared image of the plate heat exchanger sidewall obtained from field measurements in the plate heat exchanger simulation calculation model. The basic principle is that different refrigerant flow rates in the plate channels lead to different local heat transfer coefficients on the refrigerant side, resulting in differences in the heat exchange between the refrigerant and the hot-side fluid, and consequently, differences in the temperature changes of the refrigerant and the hot-side fluid along the flow direction. The temperature distribution on the plate heat exchanger sidewall is determined by the temperature distribution and local heat transfer coefficient distribution of the refrigerant and the hot-side fluid, thus indirectly reflecting the quantification of the refrigerant flow rate distribution among the plate channels in the plate heat exchanger. By adjusting the quantification of the gas-liquid two-phase refrigerant flow rate distribution in the plate heat exchanger simulation calculation model, and under the condition of satisfying the "pressure drop" limit, matching the infrared image of the plate heat exchanger sidewall obtained from field measurements, accurate quantification of the gas-liquid two-phase refrigerant flow rate distribution can be achieved. Furthermore, when the refrigerant plate channel outlet is not "superheated" and remains in a "two-phase" state, on the one hand, due to the different pressure drops in the refrigerant plate channel with different flow rates, its evaporation temperature varies; on the other hand, the different temperature profiles of the hot-side fluid caused by the different heat transfer coefficients on the refrigerant side still exist, and the sidewall temperature can still reflect the quantification of flow distribution, such as... Figure 10 As shown. Therefore, embodiments of this application do not require the refrigerant at the plate channel outlet to reach a "superheated" state.

[0214] The practical application value of the embodiments of this application is mainly reflected in the following two aspects:

[0215] First, this application provides a non-destructive, all-condition applicable "CT-like" testing method. For plate heat exchanger R&D and maintenance personnel, this application does not require damaging the product structure, nor does it require concern about whether the operating conditions meet the "outlet overheating" condition. Only by capturing infrared images of the sidewalls, this application can quantify the gas-liquid two-phase refrigerant flow distribution between each plate channel without altering the flow field or damaging the sample. This significantly lowers the measurement threshold and shortens the verification cycle for new products.

[0216] Secondly, this application provides a set of efficient sensitivity analysis and optimization tools based on automatic differentiation. The core value of this application lies not only in its accuracy but also in its speed and the ability to calculate derivatives. Specifically, by rewriting the heat exchanger model to support automatic differentiation, researchers can obtain the accurate derivative of the objective function (such as wall temperature distribution, heat exchange, etc.) with respect to any design variable (such as the flow rate of each plate channel) with extremely low time and computational cost. This not only serves flow rate inversion but also provides a core algorithm engine for the "gradient optimization design" of the heat exchanger structure, enabling designers to quickly locate key plate channels that affect performance and make targeted structural improvements.

[0217] Furthermore, the embodiments of this application have at least one of the following technical effects:

[0218] On the one hand, this embodiment uses the total pressure drop across all flow paths as a benchmark to adjust the gaseous refrigerant flow rate in each plate channel of the plate heat exchanger. Simultaneously, it utilizes the two-dimensional temperature distribution on the sidewall as observation data to construct an objective function (i.e., the target error value), quantifying the internal gas-liquid two-phase flow distribution, thereby precisely adjusting the liquid refrigerant flow rate in each plate channel of the plate heat exchanger. It should be understood that this embodiment does not limit the outlet refrigerant state; two-phase or superheated states are acceptable.

[0219] On the other hand, the embodiments of this application realize automatic differential solution of the heat exchanger simulation model, which greatly reduces the gradient calculation time and computational cost. Specifically, in order to achieve inversion, the embodiments of this application have made specific optimizations and rewrites to the traditional simulation model of plate heat exchangers (such as polynomial fitting of higher-order properties, fixed iteration number solvers, etc.), making it support automatic differential technology. Compared with the traditional finite difference method (which requires at least N+1 simulations to obtain a gradient, where N is the number of independent variables, has high computational cost and accuracy is affected by the step size), the embodiments of this application can accurately calculate the gradient of the entire wall temperature distribution with respect to the refrigerant flow rate of all plate channels in one go, improving the computational efficiency by several orders of magnitude, making real-time inversion of complex multi-plate channels possible.

[0220] On the other hand, this application's embodiments introduce "simplex projection" to update the quantization of liquid refrigerant flow distribution, achieving strict conservation of physical constraints. Specifically, in the gradient descent update stage, this application's embodiments abandon the traditional simple truncation or penalty function method and innovatively combine the simplex projection algorithm to achieve "sorting-truncation-projection". Through an analytical solution based on sorting, the Lagrange multipliers are obtained in a very short time, strictly guaranteeing from a mathematical principle that the updated liquid refrigerant flow distribution vector satisfies both non-negativity and precisely satisfies the total flow conservation, avoiding the physical paradox of "flow loss" or "negative flow" common in numerical optimization.

[0221] In summary, the embodiments of this application can effectively improve the quantitative accuracy of the flow distribution of gas-liquid two-phase refrigerant in plate heat exchangers.

[0222] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

[0223] The above is a detailed description of the preferred embodiments of this application, but this application is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for quantifying refrigerant flow distribution in a plate heat exchanger, characterized in that, The method is applied to the plate heat exchanger, which includes multiple plate channels and multiple flow paths, wherein each flow path corresponds one-to-one with a plate channel. Each plate channel is the space between two adjacent corrugated metal plates in the plate heat exchanger. Each flow path consists of the inlet manifold of the plate heat exchanger, the plate channel corresponding to the flow path, and the outlet manifold of the plate heat exchanger. Obtain the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path; If the total pressure drop values ​​of each flow path are different, the gas refrigerant flow rate of each plate channel is adjusted using the total pressure drop values ​​of each flow path, and the process returns to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path; otherwise, the temperature distribution of the outer wall of the plate heat exchanger is obtained based on the temperature value and local heat transfer coefficient of each plate channel. If the temperature distribution of the outer wall surface and the infrared image of the side wall surface of the plate heat exchanger are inconsistent, the liquid refrigerant flow rate of each plate channel is adjusted using the temperature distribution of the outer wall surface and the infrared image of the side wall surface, and the process returns to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel, as well as the total pressure drop value of each flow path; otherwise, the gas refrigerant flow rate and liquid refrigerant flow rate of each plate channel are output.

2. The method according to claim 1, characterized in that, The acquisition of the temperature value and local heat transfer coefficient of each of the plate channels, and the total pressure drop value of each of the flow paths, includes: Each of the plate channels is divided into multiple units along the length of the plate heat exchanger; wherein, the multiple plate channels include multiple hot side plate channels and multiple refrigerant side plate channels, each of the hot side plate channels includes multiple hot side units connected sequentially along the flow direction of the hot side fluid of the plate heat exchanger, and each of the refrigerant side plate channels includes multiple refrigerant side units connected sequentially along the flow direction of the gaseous refrigerant; The inlet temperature value of each of the aforementioned hot-side units is set to a preset temperature value; For each of the refrigerant side plate channels, obtain the heat transfer value of each refrigerant side unit in the current refrigerant side plate channel and its two adjacent heat side units, as well as the outlet temperature value of each refrigerant side unit in the current refrigerant side plate channel; For each of the hot side plate channels, the outlet temperature value of each of the hot side units in the current hot side plate channel is updated according to the heat exchange value between each of the hot side units in the current hot side plate channel and its two adjacent refrigerant side units. If the temperature distribution of each of the plate channels does not meet the preset conditions, the process returns to the step of obtaining the heat transfer value of each refrigerant-side unit in the current refrigerant-side plate channel and its two adjacent heat-side units, as well as the outlet temperature value of each refrigerant-side unit in the current refrigerant-side plate channel. Otherwise, the outlet temperature value of each unit in each plate channel is output as the temperature value of each plate channel, and the local heat transfer coefficient of each plate channel is determined based on the heat transfer value of each refrigerant-side unit in each refrigerant-side plate channel and its two adjacent heat-side units.

3. The method according to claim 1, characterized in that, The acquisition of the temperature value and local heat transfer coefficient of each of the plate channels, and the total pressure drop value of each of the flow paths, includes: The total pressure drop of the target flow path is obtained based on the total pressure drop of the inlet manifold corresponding to the target flow path, the total pressure drop of the outlet manifold corresponding to the target flow path, and the internal pressure drop of the plate channel corresponding to the target flow path. Wherein, the target flow path is any one of the flow paths; the inlet manifold corresponding to the target flow path is the inlet manifold section from the inlet of the plate heat exchanger to the plate channel corresponding to the target flow path; the outlet manifold corresponding to the target flow path is the outlet manifold section from the plate channel corresponding to the target flow path to the outlet of the plate heat exchanger.

4. The method according to claim 1, characterized in that, The method of adjusting the gas refrigerant flow rate of each plate channel using the total pressure drop value of each of the flow paths includes: The average total pressure drop across all flow paths is taken as the average flow path pressure drop. Based on the average pressure drop of the flow path and the total pressure drop of each flow path, the gas refrigerant flow rate of each plate channel is adjusted to obtain the adjusted gas refrigerant flow rate of each plate channel as the new gas refrigerant flow rate of each plate channel.

5. The method according to claim 1, characterized in that, The step of obtaining the temperature distribution on the outer wall surface of the plate heat exchanger based on the temperature value and local heat transfer coefficient of each plate channel includes: Based on the temperature values ​​of each of the plate channels, the hot-side fluid temperature field of the plate heat exchanger is determined, and based on the local heat transfer coefficient of each of the plate channels, the heat transfer coefficient field of the plate heat exchanger is determined. Based on the finite difference method, a three-dimensional computational mesh is established for the sidewall of the plate heat exchanger, and the temperature field of the hot-side fluid and the heat transfer coefficient field are mapped to the three-dimensional computational mesh. Using the three-dimensional computational grid, the three-dimensional steady-state heat conduction differential equation without internal heat source and its boundary conditions of the plate heat exchanger are solved iteratively to obtain the overall temperature distribution of the side wall of the plate heat exchanger. The two-dimensional temperature distribution of the outer plane is extracted from the overall temperature distribution of the sidewall as the temperature distribution of the outer wall.

6. The method according to claim 1, characterized in that, The method further includes: The error value between the temperature distribution on the outer wall surface and the infrared image of the side wall surface is obtained as the target error value; If the target error value is less than a preset error threshold, it is determined that the temperature distribution of the outer wall surface is consistent with the infrared image of the side wall surface; otherwise, it is determined that the temperature distribution of the outer wall surface is inconsistent with the infrared image of the side wall surface.

7. The method according to claim 1, characterized in that, The method of adjusting the liquid refrigerant flow rate of each plate channel using the temperature distribution of the outer wall and the infrared image of the outer wall includes: Based on the automatic differentiation method, the partial derivative of the target error value with respect to the liquid refrigerant flow rate value of each of the plate channels is obtained; wherein, the target error value is the error value between the temperature distribution of the outer wall and the infrared image of the side wall; Based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each of the plate channels, the liquid refrigerant flow rate of each of the plate channels is adjusted to obtain the adjusted liquid refrigerant flow rate of each of the plate channels as the new liquid refrigerant flow rate of each of the plate channels.

8. The method according to claim 7, characterized in that, The step of adjusting the liquid refrigerant flow rate of each plate channel based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel, and obtaining the adjusted liquid refrigerant flow rate of each plate channel as the new liquid refrigerant flow rate of each plate channel, includes: The average liquid refrigerant flow rate of all the plate channels is obtained as the average liquid refrigerant flow rate. The adaptive step size is obtained based on the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each of the plate channels and the average liquid refrigerant flow rate. Based on the adaptive step size and the partial derivative of the target error value with respect to the liquid refrigerant flow rate of each plate channel, unconstrained gradient descent processing is performed on the liquid refrigerant flow rate of each plate channel to obtain the intermediate variable vector of each plate channel. The intermediate variable vectors of each plate channel are subjected to simplex projection processing to obtain the adjusted liquid refrigerant flow rate value of each plate channel, which is then used as the new liquid refrigerant flow rate value of each plate channel.

9. The method according to claim 8, characterized in that, The step of performing simplex projection processing on the intermediate variable vectors of each plate channel to obtain the adjusted liquid refrigerant flow rate value of each plate channel as the new liquid refrigerant flow rate value of each plate channel includes: The intermediate variable vectors of each of the aforementioned plate channels are sorted and their positions are located to obtain the optimal truncation position; Based on the optimal cutoff position and the total flow rate of the liquid refrigerant, the Lagrange multiplier is obtained; Based on the Lagrange multipliers and the intermediate variable vectors of each plate channel, the adjusted liquid refrigerant flow rate value of each plate channel is obtained as the new liquid refrigerant flow rate value of each plate channel.

10. A refrigerant flow distribution and quantification device for a plate heat exchanger, characterized in that, The plate heat exchanger includes multiple plate channels and multiple flow paths, with each flow path corresponding one-to-one with a plate channel. Each plate channel is the space between two adjacent corrugated metal plates in the plate heat exchanger. Each flow path consists of the inlet manifold of the plate heat exchanger, the corresponding plate channel, and the outlet manifold of the plate heat exchanger. The device includes: The acquisition module is used to acquire the temperature value and local heat transfer coefficient of each of the plate channels, as well as the total pressure drop value of each of the flow paths; The first processing module is used to adjust the gas refrigerant flow rate of each plate channel by using the total pressure drop value of each flow path if the total pressure drop value of each flow path is different, and return to the step of obtaining the temperature value and local heat transfer coefficient of each plate channel and the total pressure drop value of each flow path; otherwise, it obtains the temperature distribution of the outer wall surface of the plate heat exchanger based on the temperature value and local heat transfer coefficient of each plate channel. The second processing module is used to adjust the liquid refrigerant flow rate of each plate channel by using the temperature distribution of the outer wall and the infrared image of the side wall of the plate heat exchanger if the temperature distribution of the outer wall and the infrared image of the side wall are inconsistent, and to trigger the acquisition module to obtain the temperature value and local heat transfer coefficient of each plate channel and the total pressure drop value of each flow path; otherwise, it outputs the gas refrigerant flow rate and liquid refrigerant flow rate of each plate channel.

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