A numerical simulation method for predicting PCHE core flow distribution uniformity and pressure drop

Abstract

The application discloses a numerical simulation method for PCHE core body flow distribution uniformity and pressure drop prediction, and belongs to the technical field of PCHE design and numerical simulation. The numerical simulation method comprises two layers of numerical simulation technology. Firstly, the first layer of numerical simulation is carried out on a single flow channel and a single plate to obtain the pressure drop of the single flow channel, the pressure drop of the plate and the proportion of each pressure drop, which are used as the basis for rapid prediction of the overall core pressure drop proportion. Meanwhile, the flow value, flow deviation and flow distribution of each flow channel on each plate can be obtained. Then, the second layer of numerical simulation is carried out on the core body formed by the sample plate and the core body adopting the sheet flow channel plate to obtain the flow of each plate and the pressure drop of the entire core body. Based on the above two layers of numerical simulation analysis, the number of grids is greatly reduced, so that the conventional hardware resources can realize the simulation analysis. Meanwhile, based on the simulation analysis result, the pressure drop and flow of the entire core body can be rapidly predicted, and more effective and reliable technical support is provided for PCHE design.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of PCHE (printed circuit heat exchanger) design, numerical simulation, and specifically relates to a numerical simulation method for predicting the flow distribution uniformity and pressure drop of a PCHE core. BACKGROUND

[0002] During the design stage of a PCHE, a very important design indicator is the flow distribution uniformity of the heat exchanger. If the flow rate of a certain flow channel does not meet the standard, it will result in low heat exchange efficiency at that position and local overheating caused by heat accumulation, which has a great impact on the heat exchange efficiency of the heat exchanger and the structural safety of the heat exchanger itself. Ensuring that each flow channel has a sufficient amount of cooling medium passing through is the basis for ensuring that the heat exchange rate of the PCHE meets the standard, and this is also the purpose of numerical simulation of the flow distribution uniformity of the PCHE. Another important design indicator is the pressure drop, which is related to the design and selection of the cooling circuit pressure head supply equipment (such as a fan), and the proportion of various resistance pressure drops in the overall pressure drop is related to the design and improvement of the heat exchanger structure. The flow distribution uniformity and pressure drop of the heat exchanger can be obtained through fluid numerical simulation calculation.

[0003] The core component of a PCHE is the core, which is composed of cold plates and hot plates. The cold and hot micro-porous flow channels pass through alternately between the cold plates and the hot plates. Generally, a helium PCHE core with a heat exchange capacity of 1000 kW will contain tens of thousands of micro-porous flow channels, with small flow channel diameters (typically in the order of 1-2 millimeters) and close arrangement (flow channel spacing is typically in the order of 2-3 millimeters). The size of the PCHE core is small, and when performing fluid numerical simulation, if each flow channel is modeled completely and the fluid domain is encrypted according to the requirements of fluid numerical simulation, the number of grids for a single flow channel is typically tens of thousands. If the tens of thousands of flow channels of the core are completely modeled, a total of hundreds of millions or even billions of grids are required. Such simulation has very high performance requirements for hardware devices (such as computers), and general hardware devices cannot achieve such large-scale calculations, making it difficult to simulate the flow distribution uniformity of the PCHE core and quickly predict the pressure drop. SUMMARY

[0004] In order to solve the problem that general hardware devices cannot achieve simulation of the flow distribution uniformity of the PCHE core and quick prediction of the pressure drop, the present application provides a numerical simulation method for predicting the flow distribution uniformity and pressure drop of a PCHE core. The numerical simulation method proposed by the present application uses multi-layer numerical simulation, which can reduce the numerical simulation resources while fully demonstrating the flow distribution uniformity of each flow channel of the core, and can quickly predict the proportion of various resistance pressure drops in the pressure head loss of the core, providing a basis for the design and improvement of the PCHE.

[0005] The present application is achieved by the following technical solutions:

[0006] A numerical simulation method for predicting PCHE core flow distribution uniformity and pressure drop, the numerical simulation method comprising:

[0007] Performing a first order numerical simulation analysis, the specific process comprising:

[0008] Performing single flow channel fluid numerical simulation and obtaining single flow channel pressure drop;

[0009] Establishing an equivalent straight-through flow channel with the same length as the non-straight-through flow channel, performing the equivalent straight-through flow channel fluid numerical simulation and obtaining the equivalent straight-through flow channel pressure drop; and subtracting the equivalent straight-through flow channel pressure drop from the non-straight-through flow channel single flow channel pressure drop to obtain the non-straight-through flow channel single flow channel local resistance pressure drop;

[0010] Performing single plate piece all flow channel fluid numerical simulation and obtaining plate piece pressure drop; and subtracting the plate piece pressure drop from the single flow channel pressure drop to obtain the head-to-plate local resistance pressure drop;

[0011] Establishing an equivalent straight-through flow channel plate piece with the same length and the same number as the non-straight-through flow channel plate piece, and performing the equivalent straight-through flow channel plate piece fluid numerical simulation and obtaining the equivalent straight-through flow channel plate piece pressure drop; and subtracting the equivalent straight-through flow channel plate piece pressure drop from the non-straight-through flow channel plate piece pressure drop to obtain the non-straight-through plate flow channel local resistance pressure drop;

[0012] Performing a second order numerical simulation analysis, the specific process comprising:

[0013] Selecting a plurality of sample plate pieces, and performing sample plate piece fluid numerical simulation containing all flow channels and obtaining each sample plate piece flow value;

[0014] Comparing and analyzing the obtained plurality of sample plate piece flow values to obtain the variation trend of different position plate piece flow values, and recursively obtaining each plate piece flow value according to the variation trend;

[0015] According to the obtained plate piece pressure drop and flow value, performing numerical fitting to obtain the plate piece corresponding permeability coefficient term and inertial resistance coefficient term;

[0016] Modeling each plate piece in the core body with an equivalent sheet flow channel plate piece, establishing a complete core body model containing all plate pieces and dividing the grid;

[0017] Applying the permeability coefficient and inertial resistance coefficient of each plate piece in the complete core body model numerical simulation to calculate the core body each plate piece flow and the entire core body pressure drop; wherein the permeability coefficient and inertial resistance coefficient are calculated according to the permeability coefficient term and inertial resistance coefficient term.

[0018] Considering that the PCHE core contains tens of thousands of micro-porous flow channels, the number of grids of a single flow channel is usually tens of thousands when numerical simulation is performed, and therefore if all the flow channels of the core are to be completely modeled, the number of grids will be in the order of hundreds of millions or even billions, and the performance of conventional hardware resources (computers) cannot realize such a scale of calculation, and it is difficult to realize fast prediction of the simulation core pressure drop of the PCHE core uniformity. The numerical simulation method proposed in the present application adopts two-layer numerical simulation technology, first, through the first layer numerical simulation: numerical simulation is performed on a single flow channel and a single plate, the pressure drop of a single flow channel, the pressure drop of a plate and the proportion of each pressure drop to the whole core pressure drop can be obtained as a basis for fast prediction of the whole core pressure drop, and at the same time, the flow rate of each flow channel on each plate, the flow rate deviation and the flow rate distribution can also be obtained; then, through the second layer numerical simulation: numerical simulation is performed on the core constructed by the sample plate and the core with the sheet flow channel plate, and the flow rate of each plate and the pressure drop of the whole core are obtained, based on the above two-layer numerical simulation analysis, the number of grids is greatly reduced, so that the conventional hardware resources can realize the above simulation analysis, and based on the simulation analysis results, the pressure drop and flow rate of the whole core can be quickly predicted, which provides more effective and reliable technical support for PCHE design.

[0019] As a preferred embodiment, the pressure drop of a single flow channel of the present application specifically includes:

[0020] For a straight-through flow channel, the pressure drop of a single flow channel is the pressure drop of the flow resistance along the single flow channel;

[0021] For a non-straight-through flow channel, the pressure drop of a single flow channel is composed of the pressure drop of the flow resistance along the single flow channel and the pressure drop of the local resistance of the single flow channel.

[0022] As a preferred embodiment, the pressure drop of a plate of the present application is composed of the pressure drop of the flow resistance along the whole plate flow channel, the pressure drop of the local resistance of the whole plate flow channel and the pressure drop of the local resistance from the header to the whole plate;

[0023] The first layer numerical simulation analysis step further includes:

[0024] The proportion of the pressure drop of the flow resistance along the whole plate flow channel and the pressure drop of the local resistance from the header to the whole plate is obtained;

[0025] And / or, the flow rate distribution value of each flow channel of a single plate is obtained.

[0026] As a preferred embodiment, the pressure drop of an equivalent straight-through flow channel plate of the present application is composed of the pressure drop of the flow resistance along the non-straight-through whole plate flow channel, the pressure drop of the local resistance of the non-straight-through whole plate flow channel and the pressure drop of the local resistance from the header to the whole plate;

[0027] The first layer numerical simulation analysis step further includes:

[0028] Obtain the proportion of the non-through whole plate flow channel along the way resistance pressure drop, the non-through whole plate flow channel local resistance pressure drop and the head to the whole plate local resistance pressure drop in the pressure drop value contribution.

[0029] As a preferred embodiment, the present application obtains the permeability coefficient term and the inertial resistance coefficient term corresponding to the plate according to the pressure drop and flow value of the obtained plate, specifically:

[0030] The full flow channel plate is equivalent to a sheet flow channel plate, and the pressure drop and flow value of the full flow channel plate obtained by the first order numerical simulation analysis are numerically fitted to obtain the permeability coefficient term and the inertial resistance coefficient term corresponding to the equivalent sheet flow channel plate.

[0031] As a preferred embodiment, the selection of the sample plate of the present application is specifically:

[0032] The selection of the sample plate is divided into the selection of the upper half core and the lower half core, and each group of sample plates includes two plates, one of which is a fixed selected plate, and the other is a plate selected according to a predetermined mode.

[0033] As a preferred embodiment, the upper half core of the present application adopts an equal interval local enumeration method to select sample plates; and the lower half core adopts an enlarged interval local enumeration method to select sample plates.

[0034] As a preferred embodiment, the second order numerical simulation analysis step of the present application further includes:

[0035] The flow value of different working conditions is used as an input condition to repeat the numerical fitting process to obtain a plurality of permeability coefficient term and inertial resistance coefficient term curves, and comparison and verification are performed to ensure the correctness of the numerical fitting.

[0036] As a preferred embodiment, the second order numerical simulation analysis step of the present application further includes:

[0037] The flow of each plate of the core obtained is compared with the flow of the corresponding position sample plate obtained to verify the correctness of the analysis.

[0038] As a preferred embodiment, the second order numerical simulation step of the present application further includes:

[0039] The flow value of the sample plate is used as a typical value to fit a curve, and the flow values of the remaining plates are generated from the fitted curve.

[0040] As a preferred embodiment, the numerical simulation method of the present application further includes: performing a mixed effect analysis according to the first order numerical simulation analysis result and the second order numerical simulation analysis result.

[0041] As a preferred embodiment, the mixed effect analysis of the present application specifically comprises:

[0042] According to the flow values of each flow channel on the plate, the flow deviation, and the flow distribution obtained in the first-order numerical simulation analysis step, the flow values, the flow deviation, and the flow distribution of the entire plate obtained in the second-order numerical simulation analysis step are combined to obtain the positions of the flow channels with the minimum and maximum flow values and the minimum flow value.

[0043] And / or, the pressure drop of the entire core obtained in the second-order numerical simulation analysis step is combined with the pressure drop ratio obtained in the first-order numerical simulation analysis step to quickly predict the ratio of various pressure losses in the entire core.

[0044] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0045] The numerical simulation method proposed in the present application adopts two-layer numerical simulation analysis technology, which can greatly reduce the hardware resources required for numerical simulation analysis while fully demonstrating the flow uniformity of each fluid in the core and quickly predicting the pressure drop of the entire core and the ratio of various resistance pressure drops in the head loss of the core, thereby providing a basis for the design and improvement of PCHE. BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present application and constitute a part of the application, do not constitute a limitation to the embodiments of the present application. In the drawings:

[0047] Figure 1 The first-order numerical simulation analysis flowchart of the embodiments of the present application;

[0048] Figure 2 The second-order numerical simulation analysis flowchart of the embodiments of the present application;

[0049] Figure 3 The schematic diagram of a certain PCHE structure of the embodiments of the present application; in the diagram, 1 is an upper half core, 2 is a lower half core, 3 is a pipe port, and 4 is a head cavity;

[0050] Figure 4a The single non-through flow channel model of the embodiments of the present application;

[0051] Figure 4b The single non-through flow channel numerical simulation grid model of the embodiments of the present application;

[0052] Figure 5 The pressure drop result of the single non-through flow channel of the embodiments of the present application;

[0053] Figure 6 The single equivalent through flow channel numerical simulation grid model of the embodiments of the present application;

[0054] Figure 7a A single-plate non-straight-through flow channel and an equivalent straight-through flow channel model of an embodiment of the present application;

[0055] Figure 7b A single-plate non-straight-through flow channel and an equivalent straight-through numerical simulation grid model of an embodiment of the present application;

[0056] Figure 7c A single-plate non-straight-through flow channel and an equivalent straight-through numerical simulation grid model of an embodiment of the present application;

[0057] Figure 8 A single-plate non-straight-through flow channel pressure drop result of an embodiment of the present application;

[0058] Figure 9 A single-plate equivalent straight-through flow channel pressure drop result of an embodiment of the present application;

[0059] Figure 10 A single-plate non-straight-through flow channel flow rate (represented by flow velocity) distribution graph of an embodiment of the present application;

[0060] Figure 11 A sample plate selection schematic diagram of an embodiment of the present application; in the diagram, 1 is an upper half core, 2 is a lower half core, 111 is an upper half core middle fixed plate, 112 is a lower half core middle fixed plate, 113 is an upper half core selected plate, and 114 is a lower half core selected plate;

[0061] Figure 12 A sample plate group model of an embodiment of the present application, which is a middle fixed plate + UP47 plate;

[0062] Figure 13 A numerical fitting graph of a sheet flow channel plate permeability coefficient item and an inertial resistance coefficient item of an embodiment of the present application;

[0063] Figure 14a A sheet flow channel plate model of an embodiment of the present application;

[0064] Figure 14b A sheet flow channel plate numerical simulation grid graph of an embodiment of the present application;

[0065] Figure 15a A model diagram of an embodiment of the present application, in which an entire core adopts an equivalent sheet flow channel plate;

[0066] Figure 15b A numerical simulation grid graph of an embodiment of the present application, in which an entire core adopts an equivalent sheet flow channel plate;

[0067] Figure 16The entire core of the embodiment of the present application is the flow distribution diagram of all the plates (expressed by flow rate). DETAILED DESCRIPTION

[0068] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be given below in combination with embodiments and drawings, the schematic embodiments of the present application and the description thereof are only used to explain the present application, and do not limit the present application.

[0069] Embodiment 1

[0070] The PCHE core contains tens of thousands of flow channels. If the flow channels of the PCHE core are completely modeled, hundreds of millions or even billions of grids are needed, and the conventional computer hardware resources are difficult to meet the computing requirements of such a large scale, so it is difficult to realize the simulation of the flow uniformity of the PCHE core and the rapid prediction of the pressure drop. In view of this, the present embodiment proposes a numerical simulation method for predicting the flow uniformity and pressure drop of the PCHE core. The numerical simulation method proposed in the present embodiment adopts a multi-level method, divides the numerical simulation into two levels, reduces the hardware resources required for numerical simulation, and at the same time can fully show the flow uniformity of each flow channel of the PCHE core, and can quickly predict the proportion of each type of resistance pressure drop in the head loss of the core, providing technical support for the design and improvement of the PCHE.

[0071] The numerical simulation method proposed in the present embodiment specifically includes:

[0072] Step 1, first-level numerical simulation analysis is performed.

[0073] Step 2, second-level numerical simulation analysis is performed.

[0074] Optionally, the numerical simulation method proposed in the present embodiment further includes:

[0075] Step 3, the mixed effect analysis is adopted to obtain the solution value of the final flow uniformity of the PCHE core, the deviation value, the flow distribution of each plate and flow channel, and the proportion of each type of pressure drop in the total pressure drop.

[0076] Further, as shown in Figure 1 The first-level numerical simulation analysis process of the present embodiment specifically includes the following sub-steps:

[0077] Step 11, single flow channel fluid numerical simulation and pressure drop are obtained. Specifically, for a straight flow channel, the pressure drop can be considered as the single flow channel resistance pressure drop. For non-straight flow channels, such as Z-shaped, S-shaped flow channels, etc., the pressure drop is composed of single flow channel resistance pressure drop and single flow channel local resistance pressure drop.

[0078] Step 12: Establish an equivalent straight-through flow channel of the same length as the non-straight-through flow channel (such as Z-shaped or S-shaped flow channel), perform fluid numerical simulation and obtain pressure drop of the equivalent straight-through flow channel; and calculate the difference between the pressure drop of the non-straight-through flow channel in Step 11 and the pressure drop of the equivalent straight-through flow channel to obtain the local resistance pressure drop of a single flow channel in the non-straight-through flow channel.

[0079] Step 13: Perform numerical simulation of the fluid flow in all channels of the single plate and obtain the pressure drop. Specifically, the pressure drop of the plate is composed of the pressure drop along the entire flow channel, the pressure drop of the local resistance of the entire flow channel, and the pressure drop of the local resistance from the end cap to the entire plate. For a straight-through flow channel plate, since its cross-section does not change in size and the flow path does not suddenly change direction, the pressure drop of the local resistance of the entire flow channel can be considered 0. Since the flow channels of the plate are arranged in parallel, the pressure drop along the flow channel of a single channel can be considered as the pressure drop along the entire flow channel. Therefore, the difference between the pressure drop of all channels of the single plate and the pressure drop obtained in Step 11 (i.e., the pressure drop along the entire flow channel) can be used to obtain the pressure drop of the local resistance from the end cap to the entire plate. Simultaneously, the ratio of the pressure drop along the entire flow channel to the pressure drop of the local resistance from the end cap to the entire plate is obtained. Furthermore, this step can also obtain the flow distribution values ​​of each channel of the plate through numerical simulation. These values ​​intuitively reflect the flow deviation of each channel on the plate and the distribution of flow in each channel.

[0080] Step 14: Establish equivalent straight-through flow channel plates of the same length and number as the non-straight-through flow channels, and perform fluid numerical simulation and pressure drop analysis on these equivalent straight-through flow channel plates. Specifically, the pressure drop of the equivalent straight-through flow channel plate consists of the frictional resistance pressure drop along the non-straight-through full-plate flow channel, the local resistance pressure drop of the non-straight-through full-plate flow channel, and the local resistance pressure drop from the end cap to the full plate. The difference between the obtained pressure drop of the equivalent straight-through flow channel plate and the pressure drop of the non-straight-through flow channel plate obtained in Step 13 yields the local resistance pressure drop of the non-straight-through full-plate flow channel.

[0081] Furthermore, the first-level numerical simulation analysis process in this embodiment also includes:

[0082] Step 15: Obtain the pressure drop along the non-straight-through flow channel, the pressure drop of the local resistance in the non-straight-through flow channel, and the proportion of the pressure drop from the end cap to the entire plate in the total pressure drop value. This pressure drop proportion can be used as a basis for rapid prediction of the overall core pressure drop proportion.

[0083] Furthermore, such as Figure 2 As shown, the second-level numerical simulation analysis in this embodiment specifically includes the following sub-steps:

[0084] Step 21, select several groups of sample plates, and carry out sample plate fluid numerical simulation and flow rate acquisition containing all the flow channels. Specifically, due to the symmetry of the core, the selection of sample plates is divided into upper and lower parts of the core. Each group of sample plates contains two plates, one of which is a fixed selected plate, and the other is a plate selected according to a certain method or variable. Preferably, in the upper part of the core, the sample plates can be selected by equal interval local enumeration method, that is, the core height direction is divided into two parts, near and far from the middle plate, and the sample plates are selected in an equal interval manner (i.e. uniformly) in the two parts. In the lower part of the core, the sample plates can be selected by expanding interval local enumeration method, that is, the core height direction is divided into two parts, near and far from the middle plate, and the sample plates are selected in an expanding interval manner in the two parts. It should be noted that in another alternative embodiment, different selection strategies can be adopted according to different core structures, such as random local enumeration method, equal difference series local enumeration method, etc.

[0085] Further, in the upper part of the core, each group of sample plates contains a core middle layer plate (i.e. a fixed selected plate) and several plates selected upward at equal intervals, such as UP1, UP3, UP5, UP7, UP45, UP47 and UP49 plates, which form 7 groups of sample plates with the fixed selected plate respectively. The first group of sample plates is the core middle layer plate + UP1 plate, the second group of sample plates is the core middle layer plate + UP3 plate, and so on, and the seventh group of sample plates is the core middle layer plate + UP49 plate.

[0086] Further, in the lower part of the core, each group of sample plates contains a core middle layer plate (i.e. a fixed selected plate) and several plates selected downward at expanding intervals, such as DOWN2, DOWN4, DOWN8, DOWN32, DOWN40, DOWN50 plates. Similarly, the first group of sample plates is the core middle layer plate + DOWN2 plate, the second group of sample plates is the core middle layer plate + DOWN4 plate, and so on, and the sixth group of sample plates is the core middle layer plate + DOWN50 plate.

[0087] Further, for each group of sample plates, the two-plate flow rate value "Q two-plate" and the working condition temperature are used as the inlet initial conditions, and the outlet can be set as pressure outlet or OUTFLOW, etc. according to the convergence speed for CFD numerical simulation. The flow rate value of each group of sample plates is obtained, which can be used as a subsequent equivalent sheet flow channel plate flow rate result single comparison verification value.

[0088] Step 22, the flow values of the obtained multiple sets of sample plates are compared and analyzed to obtain the variation trend of the flow values of the plates at different positions, and the flow value of each plate can be derived from the trend, which can be used as a comparison and verification value of the flow results of the subsequent equivalent sheet-shaped flow channel plates. Specifically, according to the experience of PCHE numerical simulation, the flow values generally show a certain regular distribution along the height direction of the core, and in this case, the obtained sample flow can be used as a typical value to fit a curve; and the flow values of the remaining plates can be generated from the curve, which can be used as a comparison and verification value of the flow results of the subsequent equivalent sheet-shaped flow channel plates.

[0089] Step 23, one plate containing all the flow channels is replaced with an equivalent sheet-shaped flow channel plate, and the permeability coefficient term and the inertial resistance coefficient term corresponding to the equivalent sheet-shaped flow channel plate are obtained by numerical fitting according to the pressure drop and flow value of the full flow channel plate obtained in step 13. Specifically, according to the mass and momentum conservation equations, it is expressed as follows:

[0090]

[0091]

[0092] The source term introduced in the momentum conservation equation and the additional pressure gradient generated therefrom are obtained, that is:

[0093]

[0094] In the above formula, γ is the filling factor, μ is the dynamic viscosity, ρ is the density, K is the permeability coefficient, and C2 is the inertial resistance coefficient.

[0095] Further, the total pressure drop (i.e. pressure gradient) of the plate obtained in step 13 is combined with the flow value of the single plate to perform curve fitting, and after fitting, the permeability coefficient term and the inertial resistance coefficient term in the above equation are obtained.

[0096] Step 24, the flow values at different working conditions are used as input conditions, and steps 13 and 23 are repeated to obtain multiple permeability coefficient term and inertial resistance coefficient term curves, which are compared and verified to ensure the correctness of the curve fitting.

[0097] Step 25, the equivalent sheet-shaped flow channel plates are used to model each plate in the heat exchanger core, a complete core model containing all the plates is established, and the grid is divided. In this embodiment, the sheet-shaped fluid domain model is used instead of the hundreds of narrow strip-shaped flow channel fluid domain models on the plate, which greatly saves the number of grids.

[0098] Step 26: Apply the permeability coefficient and inertial drag coefficient of each plate in the numerical simulation to calculate the flow rate of each plate in the core and the pressure drop of the entire core. Specifically, based on the permeability coefficient and inertial drag coefficient obtained in Step 24, calculate the permeability coefficient K and inertial drag coefficient C2 according to the fill factor γ = 1.

[0099] Step 27: Compare the flow rates of each core plate with the flow rates of the corresponding sample plates obtained in Step 22 to verify the correctness of the analysis.

[0100] Furthermore, after the second-level numerical simulation analysis, this embodiment also conducts a mixed-effects analysis according to actual needs, as follows:

[0101] Step 31: Based on the flow rate values, flow deviations, and flow distribution results of each channel on the typical plate obtained in Step 13 of the first-level numerical simulation analysis, combined with the flow rate values, flow deviations, and flow distribution of all plates obtained in Step 26 of the second-level numerical simulation analysis, the locations of the channels with the minimum and maximum flow rates are determined, and the minimum flow rate value is obtained. Furthermore, the minimum flow rate value can serve as the basis for the overall flow rate margin of the heat exchanger; that is, if the heat exchange performance of the minimum flow rate channel meets the requirements, then the overall heat exchange performance of the heat exchanger will also meet the requirements. The single-plate channel flow distribution results obtained in Step 13 of the first-level numerical simulation analysis, combined with the core plate flow distribution results obtained in the second-level numerical simulation analysis, can serve as the basis for improving the channel size and spacing.

[0102] Step 32: The pressure drop results of the entire core obtained in step 26 of the second-level numerical simulation analysis, combined with the pressure drop ratios obtained in steps 13 and 14 of the first-level numerical simulation analysis, can quickly predict the proportion of various pressure losses in the entire core, providing a basis for the overall structural improvement of the heat exchanger.

[0103] Example 2:

[0104] This embodiment uses a PCHE heat exchanger with helium as the cooling medium and Z-shaped flow channels in the plates as an example to verify the method proposed in the above embodiment. Specifically, as shown... Figure 3 As shown, the heat exchanger mainly includes a core, interface pipe 3, and end cap cavity 4. The core consists of an upper core 1 and a lower core 2. The heat exchanger contains a total of 200 plates, 100 cold plates and 100 hot plates. Each plate contains 120 flow channels with a semi-circular cross-section of 0.9 mm radius and a center-to-center spacing of 2.5 mm, arranged densely at equal intervals. The operating conditions of the cold plate of this heat exchanger are shown in Table 1 below. 8 MPa is used as the basis for selecting helium gas properties. Helium gas properties are sourced from the NIST Materials Handbook. Taking the cold plate of this heat exchanger as an example:

[0105] Table 1

[0106]

[0107]

[0108] First, we perform the first level of numerical simulation:

[0109] Step 11, as follows Figure 4a As shown, a three-dimensional model of the Z-shaped flow channel is established, and the boundary layer mesh is set according to the mesh generation requirements of fluid numerical simulation. The fluid domain mesh is then divided as follows. Figure 4b As shown, the total number of grids is approximately 80,000. The flow rate of operating condition 1 is selected and the flow rate is evenly distributed according to the total number of flow channels to obtain the flow rate "Q_single" of a single flow channel. "Q_single" and the inlet temperature are applied as the initial inlet boundary conditions in the three-dimensional numerical simulation. The outlet is set to OUTFLOW according to the convergence expectation, that is, the initial pressure is 0 MPa. This outlet pressure can also be set to 8 MPa. The setting of this initial value of the outlet pressure has no effect on the pressure drop analysis results.

[0110] The pressure drop distribution of the single flow channel was obtained after the calculation was completed, as shown below. Figure 5 As shown, the pressure drop is 9.44 kPa.

[0111] Step 12, as follows Figure 6 As shown, a numerical simulation model of a straight-through flow channel with the same length as the Z-shaped flow channel was established and meshed. The "Q_single" value and inlet temperature were applied as initial inlet boundary conditions in the three-dimensional numerical simulation. The outlet was set to OUTFLOW according to the convergence expectation, i.e., the initial pressure was 0 MPa. The calculated pressure drop of this single flow channel was 9.04 kPa.

[0112] The difference between the pressure drop obtained in step 11 and the pressure drop of the equivalent straight-through channel is calculated to obtain a local resistance pressure drop of 0.4 kPa for a single Z-shaped channel. It can also be seen that for this type of microporous channel, the channel cross-sectional radius is much smaller than the channel length, and the pressure loss caused by friction along the channel accounts for the vast majority.

[0113] Step 13: Establish a fluid domain model of the cooling plate containing all flow channels and mesh it. Select the flow rate of operating condition 1 and distribute the flow rate evenly according to the total number of cooling plates to obtain the flow rate of a single plate "Q_plate". Apply "Q_plate" and the inlet temperature as the initial inlet boundary conditions to the three-dimensional numerical simulation model. Set the outlet to OUTFLOW according to the convergence expectation, that is, the initial pressure is 0MPa.

[0114] Step 14: Create a straight flow channel plate with the same length as the Z-shaped flow channel, and apply the "Q plate" and inlet temperature as the initial inlet boundary conditions in the three-dimensional numerical simulation model. Set the outlet to OUTFLOW according to the convergence expectation, that is, the initial pressure is 0MPa.

[0115] To save the calculation time, the numerical analysis model of step 13 and step 14 is established in the same example in this embodiment, but the fluid boundary is independent of each other, and it is two numerical simulation models that do not affect each other, as shown in Figure 7a According to the requirements of fluid numerical simulation grid division, the boundary layer grid is set, and the fluid domain grid is divided as shown in Figure 7b and Figure 7c Among them, Figure 7c is the display of local encryption excessive grid, the model grid number is 21.23 million, it is worth noting that this is only the grid number of two plate flow channels, and if the fluid domain of all flow channels of the full core body is established, the grid number needs to be multiplied by 100 pieces, that is, the grid number will reach billions of levels.

[0116] The calculation obtains the pressure drop distribution of the non-through Z-shaped flow channel cooling plate as shown in Figure 8 The numerical value is 10.07 KPa. The pressure drop distribution of the cooling plate of the straight-through flow channel is as shown in Figure 9 The numerical value is 9.607 KPa. The difference between the two is obtained, and the local resistance pressure drop of the Z-shaped flow channel plate is 10.07 KPa-9.607 KPa=0.463 KPa. This is very close to the numerical value of 0.4 KPz obtained by the single flow channel simulation result, which is verified before and after the numerical simulation result. The local resistance pressure drop from the head to the whole plate is 10.07 KPa-9.44 KPa=0.63 KPa. At the same time, it can be known that, since the flow channel cross-section radius of the micro-porous flow channel heat exchanger is much smaller than the flow channel length, the pressure loss caused by the flow channel resistance along the way accounts for a large part, about 90%. Whether it is flow channel local resistance or local resistance from head to plate, it accounts for only about 4.5% and 6%. It is proved that the pressure head loss of the heat exchanger is within the design requirements and the flow channel shape and head cavity design are reasonable, and there is no large local resistance loss.

[0117] The calculation also obtains the flow distribution diagram of all flow channels on the Z-shaped flow channel plate, as shown in Figure 10 In the numerical analysis software, the flow is directly represented by the flow rate, and the flow rate can be linearly converted. The conversion formula is: flow rate=flow / (density*flow cross-sectional area). These numerical values directly reflect the flow deviation of each flow channel on the plate and the distribution state of the flow in each flow channel. As can be seen from the figure, the maximum deviation of the flow speed distribution on the plate is-0.5%~+0.3%.

[0118] Then the second layer numerical simulation analysis is carried out:

[0119] Step 21, as shown in Figure 11As shown, according to the upper half of the core 1, the middle fixed plate piece 111 + the enumeration method of the local interval is selected to select 7 groups of plate pieces 113 (i.e. UP1, UP3, UP5, UP7, UP45, UP47, UP49). The lower half of the core 2 selects the middle fixed plate piece 112 + the enumeration method of the local interval is selected to select 6 groups of plate pieces 114 (i.e. DOWN2, DOWN4, DOWN8, DOWN32, DOWN40, DOWN50). The two plate pieces of each group establish a fluid domain numerical simulation model containing all the flow channels, such as Figure 12 The middle fixed selection plate piece + UP47 plate piece sample group model is shown. The flow rate of working condition 1 is evenly divided by the total number of cold plates, multiplied by 2 to obtain the flow rate of two plate pieces "Q two plate", and "Q two plate" and the inlet temperature are used as the initial inlet boundary conditions in the three-dimensional numerical simulation model. The outlet is set as OUTFLOW according to the convergence expectation, that is, the initial pressure is 0 MPz. After calculation, the flow rate (flow rate) value of the middle fixed plate piece and each selected plate piece is obtained.

[0120] Step 22, compare and analyze the multiple groups of flow rate values obtained in step 21 or curve fitting to obtain the flow rate values of other plate pieces.

[0121] Step 23, replace a plate piece containing all flow channels with an equivalent sheet flow channel plate piece, and according to the pressure drop (converted to pressure gradient) and initial flow rate value (converted to flow rate) of the plate piece obtained in step 13, numerical fitting is performed to obtain the fitting diagram of the permeability coefficient term and the inertial resistance coefficient term of the equivalent sheet flow channel plate piece as shown. Figure 13

[0122] Step 24, select other flow rates such as 0.5 kg / s, repeat steps 13 and 23, which are not shown here. And compare the fitting curves of the permeability coefficient term and the inertial resistance coefficient term obtained in this step with step 23. In this embodiment, the fitting results are very small, and the numerical values of the permeability coefficient term and the inertial resistance coefficient term can be obtained according to step 23, that is, Figure 13 Results.

[0123] Step 25, each plate piece is modeled with a sheet flow channel plate piece, as shown. Figure 14a Figure 14b The grid division model of the sheet flow channel is shown. It can be seen that the number of grids of the sheet flow channel is much smaller than the number of grids of the flow channel fluid domain of Figure 7b .

[0124] After replacing all the flow channels in the cold plate pieces in the PCHE heat exchanger with sheet flow channel models, a complete core model is established, as shown. Figure 15a Figure 15b ​​​At this time, the total grid of the core body together with the head cavity fluid domain is about 20 million, which is greatly reduced compared with the grid number of billions required for establishing all the flow channels in the foregoing, and the calculation scale is greatly reduced. At this time, the numerical calculation achieves the purpose of replacing the hundreds of long and narrow strip-shaped flow channel fluid domain model on the plate with the sheet-shaped fluid domain model, greatly saving the number of grids, and making the numerical simulation of flow distribution have the possibility of calculation on a conventional computer workstation.

[0125] Step 27, the permeability coefficient and the inertial resistance coefficient of each plate obtained in step 23 are calculated according to the filling factor γ = 1 to obtain the permeability coefficient K and the inertial resistance coefficient C2, as shown in Table 2 below:

[0126] Table 2

[0127]

[0128] The two coefficients are substituted into the commercial fluid numerical simulation software to perform numerical simulation to obtain the flow distribution and flow deviation value of each plate (the flow rate output in the software), as shown in Figure 16 It can be seen from the figure that the maximum deviation of the plate flow channel velocity distribution is-2.8% to +4.2%. The flow value of the equivalent sheet-shaped flow channel plate obtained in this step can be compared and verified with the sample plate flow value obtained in steps 21 and 22 to judge the correctness of the analysis result, and the comparison process is not exemplified here.

[0129] Then, after the second layer numerical simulation analysis is completed, the mixing effect analysis can be carried out according to the actual needs, as follows:

[0130] Step 31, according to steps 14 and 26, the maximum deviation of the plate flow channel flow rate (flow) distribution is (100%-2.8%)*(100%-0.5%)-100% to (100%+4.2%)*(100%+0.3%)-100%, that is, -3.3% to +4.5%.

[0131] According to Figure 16 Combined with Figure 10 It can be judged that the maximum negative deviation of the flow occurs at the 41st flow channel position of the distal plate of the core body, and gradually increases slowly along the height direction of the core body to the middle layer.

[0132] Step 32, the total pressure drop of the core body is 14.2 KPa, and it can be known from step 14 that the pressure loss caused by the flow channel resistance is about 90%, about 12.8 KPa. Therefore, whether the local resistance of the flow channel is 4.5%, about 0.6 KPa, or the local resistance from the head to the plate is 6%, about 0.8 KPa, the heat exchanger meets the requirements, so the heat exchanger form is reasonable and there is no large local resistance loss.

[0133] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In one

[0134] The present application is described in reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart Figure 1 one or more functions specified in the flowchart block or blocks. Figure 1 means for carrying out each of the

[0135] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the Figure 1 one or more functions specified in the flowchart block or blocks. Figure 1 means for carrying out each of the

[0136] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the Figure 1 one or more functions specified in the flowchart block or blocks. Figure 1 means for carrying out each of the

[0137] The specific embodiments described above have been disclosed by way of example and that, therefore, any modifications and / or substitutions are possible without departing from the scope of the application as defined by the appended claims.

Claims

1. A numerical simulation method for PCHE core flow distribution uniformity and pressure drop prediction, characterized in that, The numerical simulation method comprises: The first order numerical simulation analysis is performed, and the specific process comprises: The single flow channel fluid numerical simulation is performed to obtain the pressure drop of the single flow channel; The equivalent straight-through flow channel with the same length as the non-straight-through flow channel is established, the equivalent straight-through flow channel fluid numerical simulation is performed to obtain the pressure drop of the equivalent straight-through flow channel, and the pressure drop of the equivalent straight-through flow channel is subtracted from the pressure drop of the single flow channel of the non-straight-through flow channel to obtain the local resistance pressure drop of the single flow channel of the non-straight-through flow channel; The single plate piece all-flow-channel fluid numerical simulation is performed to obtain the pressure drop of the plate piece, and the pressure drop of the plate piece is subtracted from the pressure drop of the single flow channel to obtain the local resistance pressure drop from the head to the whole plate; The equivalent straight-through flow channel plate piece with the same length and the same number as the non-straight-through flow channel is established, the equivalent straight-through flow channel plate piece is subjected to the fluid numerical simulation, and the pressure drop of the equivalent straight-through flow channel plate piece is obtained; the pressure drop of the equivalent straight-through flow channel plate piece is subtracted from the pressure drop of the non-straight-through flow channel plate piece to obtain the local resistance pressure drop of the whole plate flow channel of the non-straight-through flow channel; The second order numerical simulation analysis is performed, and the specific process comprises: A plurality of sample plate pieces are selected, and the sample plate piece fluid numerical simulation containing all flow channels is performed to obtain the flow value of each sample plate piece; The obtained flow values of the plurality of sample plate pieces are compared and analyzed to obtain the variation trend of the flow values of the plate pieces at different positions, and the flow value of each plate piece is recursively obtained according to the variation trend; The numerical fitting is performed according to the obtained pressure drop and flow value of the plate piece to obtain the permeability coefficient term and the inertial resistance coefficient term corresponding to the plate piece; The equivalent piece-shaped flow channel plate piece is used for modeling each plate piece in the core body, a complete core body model containing all plate pieces is established, and the mesh is divided; The permeability coefficient and the inertial resistance coefficient of each plate piece are applied in the numerical simulation of the complete core body model to calculate the flow of each plate piece and the pressure drop of the whole core body, wherein the permeability coefficient and the inertial resistance coefficient are calculated according to the permeability coefficient term and the inertial resistance coefficient term.

2. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction according to claim 1, characterized in that, The pressure drop of the single flow channel comprises: For the straight-through flow channel, the pressure drop of the single flow channel is the single flow channel along the way resistance pressure drop; For the non-straight-through flow channel, the pressure drop of the single flow channel is composed of the single flow channel along the way resistance pressure drop and the single flow channel local resistance pressure drop.

3. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction of claim 1, wherein, The pressure drop of the plate piece is composed of the whole plate flow channel along the way resistance pressure drop, the whole plate flow channel local resistance pressure drop and the local resistance pressure drop from the head to the whole plate; The first order numerical simulation analysis step further comprises: The proportion of the whole plate flow channel along the way resistance pressure drop and the local resistance pressure drop from the head to the whole plate is obtained; And / or, the flow distribution value of each flow channel of the single plate piece is obtained.

4. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction of claim 1, wherein, The pressure drop of the equivalent straight-through flow channel plate piece is composed of the non-straight-through whole plate flow channel along the way resistance pressure drop, the non-straight-through whole plate flow channel local resistance pressure drop and the local resistance pressure drop from the head to the whole plate; The first order numerical simulation analysis step further comprises: The proportion of the non-straight-through whole plate flow channel along the way resistance pressure drop, the non-straight-through whole plate flow channel local resistance pressure drop and the local resistance pressure drop from the head to the whole plate in the pressure drop value contribution is obtained.

5. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction of claim 1, wherein, The numerical fitting is performed according to the obtained pressure drop and flow value of the plate piece to obtain the permeability coefficient term and the inertial resistance coefficient term corresponding to the plate piece, and specifically, The full-flow channel plate is equivalent to a sheet-shaped flow channel plate, and the permeability coefficient term and the inertial resistance coefficient term corresponding to the equivalent sheet-shaped flow channel plate are obtained by numerical fitting according to the pressure drop and flow value of the full-flow channel plate obtained through the first-order numerical simulation analysis.

6. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction of claim 1, wherein, The selection of the sample plate is specifically as follows: The selection of the sample plate is divided into the selection of the sample plate of the upper half core body and the sample plate of the lower half core body, and each group of sample plates includes two plates, one of which is a fixed selected plate, and the other is a plate selected according to a preset mode.

7. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction of claim 6, wherein, The sample plate of the upper half core body is selected by using an equal-interval local enumeration method, and the sample plate of the lower half core body is selected by using an enlarged-interval local enumeration method.

8. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction of claim 6, wherein, The second-order numerical simulation analysis step further includes: The flow values of different working conditions are used as input conditions to repeat the numerical fitting process, and a plurality of permeability coefficient term and inertial resistance coefficient term curves are obtained to ensure the correctness of the numerical fitting through comparison and verification.

9. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction of claim 6, wherein, The second-order numerical simulation analysis step further includes: The flow values of the plates of the core body obtained are compared with the flow values of the sample plates at the corresponding positions to verify the correctness of the analysis.

10. The numerical simulation method for PCHE core flow uniformity and pressure drop prediction of claim 6, wherein, The second-order numerical simulation step further includes: The flow value of the sample plate is used as a typical value to fit a curve, and the flow values of the remaining plates are generated from the fitted curve.

11. The numerical simulation method of PCHE core flow uniformity and pressure drop prediction according to any one of claims 1-10, characterized in that, The numerical simulation method further includes: performing a mixed effect analysis according to the first-order numerical simulation analysis result and the second-order numerical simulation analysis result.

12. The numerical simulation method of PCHE core flow uniformity and pressure drop prediction of claim 11, wherein, The mixed effect analysis specifically includes: The numerical simulation method further includes: According to the flow values, flow deviations and flow distributions of the plates obtained through the first-order numerical simulation analysis step and the flow values, flow deviations and flow distributions of all the plates obtained through the second-order numerical simulation analysis, the positions of the flow channels with the minimum flow and the maximum flow are obtained, and the minimum flow value is obtained; And / or, according to the pressure drop of the entire core body obtained through the second-order numerical simulation analysis step and the pressure drop proportion obtained through the first-order numerical simulation analysis step, the proportions of various pressure losses in the entire core body are quickly predicted.

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