Heat transfer simulation method, system, device and medium for material sublimation drying process

Abstract

The application discloses a heat transfer simulation method, system and device for a material sublimation drying process and a medium, belongs to the sublimation drying technical field, and solves the technical problem that a scientific and standardized method is lacked for judging the end point of the existing agricultural product sublimation drying. F , a soluble solid volume fraction V C , an ice crystal volume fraction Vi and a porosity ɛ; a sublimation critical temperature T f→g of the material is calculated; water vapor saturation S g and ice saturation S i in the material in the sublimation drying process are calculated; effective material property parameters in the sublimation process are obtained; a sublimation rate source term of the material sublimation drying process is calculated; and a mass transfer model and a heat transfer model of the material sublimation drying process are constructed. The application has the beneficial effect that a heat transfer simulation method for a material sublimation drying process is provided, which can accurately predict the temperature, phase change and sublimation end point of the sublimation drying process, and realizes the standardization of the material sublimation drying production.

Description

Technical Field

[0001] This invention relates to the field of material sublimation drying technology. More specifically, this invention relates to a method, system, apparatus, and medium for simulating heat transfer during the material sublimation drying process. Background Technology

[0002] The sublimation drying process comprises three stages: freezing, sublimation, and desorption drying. The sublimation drying stage is typically conducted at low pressure and low temperature (temperature ≤ 0.0098 degrees Celsius, pressure ≤ 4.58 mmHg). By reducing the pressure in the drying chamber, the ice in the sublimated material is directly converted into a gaseous state (sublimation). This process avoids the liquid stage and is suitable for heat-sensitive materials such as food and pharmaceuticals, effectively removing moisture while preserving the material's structure and active ingredients. In sublimation drying, the generated water vapor is cooled and captured in a cold trap, thus achieving drying.

[0003] Analytical drying occurs during the heating stage of sublimation drying, ideally after sublimation drying is complete. Currently, most companies rely on the experience of production operators to determine the sublimation endpoint, a method that is highly subjective and difficult to guarantee consistency. During sublimation drying, the sublimation endpoint varies significantly between different agricultural products and even between different batches of the same product. Therefore, relying solely on experience is easily influenced by factors such as the operator's experience level and the product's origin, making it difficult to ensure standardized production. Installing temperature detection equipment during the sublimation process to monitor the internal temperature of the product to determine the sublimation endpoint is a common method for detecting the endpoint of material sublimation drying. However, due to the limited number of temperature sensor detection points and the variability of agricultural products, the temperature monitoring results lack universality. Furthermore, the temperature sensor detection process is invasive, which can damage the original external structure of the material, affecting the consistency of the sublimated dried product. Therefore, the lack of a scientific and standardized method for determining the endpoint of agricultural product sublimation drying significantly impacts the stability of the sublimation drying production cycle and product quality. Therefore, in the future, it is necessary to develop more convenient, accurate, and reliable methods for predicting the sublimation endpoint by combining the characteristics of agricultural products and operating parameters, so as to accurately optimize the sublimation drying process and production cycle, achieve more energy-saving and green sublimation drying production, and ultimately improve the standardization of sublimation drying production.

[0004] Simulation can use mathematical modeling based on actual production parameters and material properties to accurately predict physical and chemical changes during processing and optimize processing techniques. Agricultural products, such as fruits and vegetables, are mainly rich in water, soluble solids, and crude fiber. Applying mathematical simulation to the sublimation drying process of agricultural products, coupling the properties of the products with sublimation drying parameters, allows for advance prediction of the temperature, pressure, and endpoint of the sublimation drying process based on the differences in the physical properties of different agricultural products and the sublimation drying conditions. This avoids over- or under-sublimation drying, provides accurate references for subsequent heating operations, and reduces production costs. Currently, no simulation method has been proposed for the sublimation drying process to predict the temperature, phase transition, and endpoint of the sublimation drying process, thus achieving standardization in the sublimation drying production of materials (especially agricultural products). Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0006] Another objective of this invention is to provide a heat transfer simulation method for the sublimation drying process of materials, which can accurately predict the temperature, phase change and sublimation endpoint of the sublimation drying process. The applicable simulation conditions are in the range of −100℃ to the material sublimation temperature point, thereby achieving standardization of the sublimation drying production of materials (especially agricultural products).

[0007] To achieve these objectives and other advantages according to the present invention, a method for simulating heat transfer during a material sublimation drying process is provided, comprising the following steps:

[0008] Step 1: Based on the material's composition parameters, obtain the crude fiber volume fraction V of the material during the sublimation drying process. F soluble solids volume fraction V C Ice crystal integral number Vi, porosity α;

[0009] Step 2: Based on the parameters in Step 1, obtain the critical sublimation temperature T of the material under vacuum during the vacuuming process. f→g K; when the geometric mean temperature of the material is greater than or equal to the sublimation critical temperature T. f→g Sublimation occurs at that time;

[0010] Step 3: Predict the sublimation endpoint of the material using the following calculation steps: S1, Calculate the ice saturation S of the material at the current time and space. i and water vapor saturation S g S2. Based on the parameters in step one and step S1, calculate the effective thermal conductivity γ of the porous medium of the material under the current time and space conditions. s Effective density ρ of porous media s Effective specific heat capacity Cp of porous media sThe effective thermal conductivity γ of the sublimation phase f Effective density of sublimation phase ρ f Sublimation phase effective specific heat capacity Cp f S3. Based on the parameters in Step 1 and Steps S1-S2, calculate the sublimation rate source term of the material in the current time and space. S4. Based on the parameters in Step 1 and Steps S1 to S3, calculate the water vapor pressure P and water vapor density ρ of the material in the current time and space. g 1. Water vapor velocity μ; S5. Calculate the material temperature in the current time and space based on the parameters in steps 1 to 2 and steps S1 to S4; S6. Use the material temperature in the current time and space obtained in S5 as the input parameter in S1, and repeat steps S1 to S5 to solve for the material temperature in the next time and space; S7. Repeat steps S1 to S6 to finally calculate the ice saturation S of the material. i The spatiotemporal distribution field; when the ice saturation S of the material at any point... i When all values ​​are 0, the sublimation process reaches its endpoint.

[0011] Preferably, in step two, the sublimation critical temperature T of the material is... f→g Obtain it in the following way:

[0012] A1. Determine the geometric mean temperature T of the material during the vacuuming process. mean The curve that changes over time yields tT mean The curve, where t is any time point during the vacuuming process; where T mean Solve it in the following way:

[0013] A11. Construct a heat transfer model for the material during the vacuuming process, as follows:

[0014] ;

[0015] ρ eff The effective density of a material is expressed in kg / m³. 3 ;

[0016] Cp eff The effective specific heat capacity of the material is expressed in J / (kg·K).

[0017] γ eff The effective thermal conductivity of a material is expressed in W / m·K.

[0018] Cp F The value represents the specific heat capacity of the crude fiber in the material, J / (kg·K).

[0019] Cp C The specific heat capacity of soluble solids in a material is expressed in J / (kg·K).

[0020] Cp i The specific heat capacity of ice in the material is expressed in J / (kg·K).

[0021] γ F This represents the thermal conductivity of the coarse fibers in the material, expressed in W / (m·K).

[0022] γ C It represents the thermal conductivity of the soluble solids in a material, in W / (m·K);

[0023] γ i This represents the thermal conductivity of the material, expressed in W / (m·K).

[0024] Q1 represents the heat radiated by the environment to the material, in J;

[0025] Q2 represents the heat transferred from the shelf to the material, in J;

[0026] Q3 represents the heat transferred to the material by gas convection, in J;

[0027] T a Indicates the ambient temperature of the vacuum chamber, in K;

[0028] T p This indicates the temperature of the vacuum chamber shelf, in K;

[0029] h p This indicates the heat transfer coefficient of the shelf, 26 W / (m²). 2 ·K);

[0030] h a This represents the gas convective heat transfer coefficient, 1.54 × 10⁻⁶. −3 ×P c W / (m 2 ·K);

[0031] This indicates the surface emissivity factor, which is determined during demolding and vacuuming. =0.97, when vacuuming without demolding. =0.2;

[0032] σ represents the Stevie-Boltzmann constant, 5.676 × 10⁻⁶. −8 W·m −2 ·K −4 ;

[0033] T represents the temperature at any point in time during the sublimation and drying process of the material, in K;

[0034] A12. Using the above heat transfer model, the spatiotemporal field of the material temperature during the vacuuming process is obtained; during the vacuuming process, the average temperature of each point inside the material at each moment is taken to obtain the geometric mean temperature T of the material at each moment. mean, thereby obtaining tT mean curve;

[0035] A2. Determine the sublimation temperature T corresponding to the vacuum chamber pressure during the vacuuming process. 升 , obtain tT 升 curve;

[0036] ;

[0037] P c The pressure in the vacuum chamber is expressed in Pa and P. c =1.01×10 5 +(P A –1.01×10 5 )×t / t down ;P A The target pressure of the vacuum chamber is expressed in Pa; t down This indicates that the pressure in the vacuum chamber decreases from atmospheric pressure to the target pressure P. A The time taken, min; ΔH f→g Indicates latent heat of sublimation, J / kg; ;T t The triple point temperature is 273.15 K.

[0038] A3、tT mean Curve and tT 升 The temperature corresponding to the intersection of the curves is the critical sublimation temperature T of the material. f→g .

[0039] In the above technical solution, during the sublimation drying process, the material is first evacuated. The material is dried when its geometric mean temperature is greater than or equal to its critical sublimation temperature T. f→g Sublimation occurs at that time; in step A1, T mean It is the geometric mean temperature of the material during the vacuuming process, therefore T is calculated. mean In the heat transfer model used, the value of t can usually be regarded as being within (0, t). down Within this time frame.

[0040] Preferably, step three specifically includes the following steps:

[0041] S1. Calculate the ice saturation S of the material at the current time and space. i and water vapor saturation S g ,

[0042] S i =1-S g ;

[0043] ΔTf→g =0.5K; T is the temperature of the material in the previous time space, in K;

[0044] S2. Based on the parameters in Step 1 and Step S1, obtain the effective physical property parameters of the material under the current time and space. The effective physical property parameters include the effective thermal conductivity γ of the porous medium. s Effective density ρ of porous media s Effective specific heat capacity Cp of porous media s The effective thermal conductivity γ of the sublimation phase f Effective density of sublimation phase ρ f Sublimation phase effective specific heat capacity Cp f ;

[0045] S3. Based on the parameters in Step 1 and Steps S1-S2, calculate the sublimation rate source term of the material in the current time and space. kg / (m 3 s), ;

[0046] S4. Based on the parameters from steps one and S1 to S3, construct a mass transfer model. Using the mass transfer model, calculate the water vapor pressure P and water vapor density ρ of the material at the current time and space. g The water vapor velocity μ; the mass transfer model is:

[0047] ;

[0048] D eff The effective diffusion rate of water vapor is represented by m. 2 / s;

[0049] κ represents the Darcy permeability of water vapor, m 2 ;

[0050] pore represents the average pore size of the material, in μm; pore = 1.47 + 7.44 e ( T1+ 196) / 85.35 , μm, where T1 represents the freezing temperature;

[0051] M g This represents the molar mass of water vapor, 18 g / mol.

[0052] R represents the ideal gas constant, 8.314 J / (mol·K);

[0053] μ g The viscosity of water vapor is expressed in kg / (m∙s).

[0054] S5. Based on the parameters from steps one to two and steps S1 to S4, construct a heat transfer model. Using this model, calculate the material temperature T at the current time and space. The heat transfer model is as follows:

[0055] ;

[0056] Cp g This represents the specific heat capacity of water vapor, J / kg / K, 1674.7 J / kg / K;

[0057] γ g The value represents the thermal conductivity of water vapor, W / m·K, 0.025 W / m / K;

[0058] S6. Using the material temperature T obtained in S5 under the current time and space as the input parameter in S1, repeat steps S1 to S5 to solve for the material temperature T under the next time and space.

[0059] S7. Repeat steps S1 to S6 above to finally calculate the ice saturation S of the material. i The spatiotemporal distribution field; based on ice saturation S i The spatiotemporal distribution field, when the ice saturation S of the material at any point... i When all values ​​are 0, the sublimation process reaches its endpoint.

[0060] In the above technical solution, considering the influence of soluble solids content and freezing temperature on the average pore size of the material during sublimation, under ideal conditions (coarse fiber content in the material is 0), the mass fraction of soluble solids in the material was set in a gradient (5%, 10%, 20%, 40%), and the freezing temperature was set (20℃, 40℃, 80℃, 196℃). The average pore size in the material was obtained experimentally for each. The average pore size in the material was fitted with the mass fraction of soluble solids and the freezing temperature, respectively. It was found that the soluble solids content has a relatively small impact on the average pore size of the material, while the freezing temperature has a relatively large impact. The fitting equation for the average pore size of the material and the freezing temperature is: average pore size pore = 1.47 + 7.44 e ( T1+ 196) / 85.35 μm, T1 represents the freezing temperature. The unit of water vapor pressure P is Pa, and the density of water vapor ρ... g The unit is kg / m 3 The unit of water vapor velocity μ is m / s;

[0061] Furthermore, in step S1, the initial spacetime T represents the temperature at every point inside the material when sublimation begins. First, the ice saturation S at every point inside the material at the initial moment is calculated. i and water vapor saturation S gThen, the effective physical properties, sublimation rate, water vapor pressure, water vapor density, and water vapor velocity of the material at the initial moment are calculated sequentially. These calculated parameters are then substituted into the heat transfer model to calculate the material temperature T at the next time point. By using finite difference iterative calculations, the ice saturation at any point within the material at any time can be obtained, i.e., the spatiotemporal distribution field of the material's ice saturation. In practical applications, the ice saturation S in step S6 is obtained... i After determining the spatiotemporal distribution field of S, further analysis of S is possible. i The spatiotemporal distribution field is solved to obtain the remaining ice crystal content during the material sublimation process (this is a conventional solution method in this field, which will not be elaborated on here). When the remaining ice crystal content is 0, it is the sublimation endpoint. Such calculation results are more intuitive and convenient.

[0062] Preferably, in step one, the methods for obtaining each parameter are as follows:

[0063] crude fiber volume fraction V F ,%V F =(X F / ρ F ) / (X F / ρ F +X w / ρ i +X c / ρ C );

[0064] Soluble solids volume fraction V C ,%V C =(Xc / ρ C ) / (X F / ρ F +Xw / ρ i +Xc / ρ C );

[0065] Ice crystal integral V i ,%V i =(1−V F -V C );

[0066] Porosity ɛ, %, ɛ=1−V F -V C ;

[0067] Among them, X W This indicates the mass fraction of moisture in a material, expressed as % .

[0068] X C This indicates the mass fraction of soluble solids in a material, expressed as % .

[0069] X FThis indicates the mass fraction of crude fiber in the material, expressed as % .

[0070] ρ i This indicates the density of ice, in kg / m³. 3 , ρ i =916.89−0.1307×T;

[0071] ρ C This indicates the density of the soluble solids in the material, expressed in kg / m³. 3 , ρ C =1599.1−0.31046×T;

[0072] ρ F This indicates the coarse fiber density of the material, in g / m³. 3 , ρ F =1311.5−0.36589×T.

[0073] Preferably, in step A1:

[0074] The specific heat capacity Cp of the crude fiber of the material F =1845.9+1.8306×T×(−0.0046509)×T 2 ;

[0075] Specific heat capacity Cp of soluble solids in material C =1548.8+1.9625×T×(−0.0059399)×T 2 ;

[0076] Specific heat capacity of ice in material Cp i =2062.3+6.0769×T;

[0077] The thermal conductivity γ of the coarse fiber of the material F =0.18331+0.0012497×T−3.1683×10 −6 ×T 2 ;

[0078] Thermal conductivity γ of soluble solids in material C =0.20141+0.0013874×T−4.3312×10 −6 ×T 2 ;

[0079] The thermal conductivity γ of the material ice i =2.2196−6.2489×10 −3 ×T+1.0154×10 −4 ×T 2 .

[0080] Preferably, in step S2:

[0081] The effective thermal conductivity γ of porous matrix S W / (m·K), γ S =(V F ×γ F ) / (V F +S g ×V C )+(S g ×V C ×γ C ) / (V F +S g ×V C );

[0082] Effective density ρ of porous matrix S kg / m 3 , ρ S =(V F ×ρ F ) / (V F +S g ×V C )+ (S g ×V C ×ρ C ) / (V F +S g ×V C );

[0083] Effective specific heat capacity Cp of porous matrix S J / kg / K, Cp S =(Cp F ×X F ) / (X F +S g ×X C )+(S g ×Cp C ×X C ) / (X F +Sg×X C );

[0084] The effective thermal conductivity γ of the sublimation phase f W / (mK), γ f =(V i ×γ i ) / (V i +V C )+(S i ×V C ×γ C ) / (V i +V C );

[0085] Sublimation phase effective density ρ f kg / m3 , ρ f =(V i ×ρ i ) / (V i +V C )+(S i ×V C ×ρ C ) / (V i +V C );

[0086] Sublimation phase effective specific heat capacity Cp f J / kg / K, Cp f =(S i ×Cp i ×X i ) / (X i +X C )+(S i ×Cp C ×X C ) / (X i +X C ).

[0087] Preferably, the method further includes a step of coupling the mass transfer model and heat transfer model of the material sublimation process obtained in steps S4 and S5 with the axisymmetric material shape to construct heat transfer and mass transfer models of the sublimation process of materials with different axisymmetric shapes. Specifically, the material dimensions are obtained using COMSOL Multiphysics software, a geometric model of the material is constructed and the mesh is refined, and the mass transfer model in step S4 and the heat transfer model in step S5 are solved under the boundary conditions constrained by the geometric model of the material.

[0088] A heat transfer simulation system based on the heat transfer simulation method of material sublimation drying process includes:

[0089] The input module is used to input at least the mass fraction X of moisture in the material. W Mass fraction of soluble solids in the material X C Mass fraction of crude fiber in the material X F The initial temperature of the material T0, the freezing temperature of the material T1, and the ambient temperature of the vacuum chamber T a Vacuum chamber shelf temperature T p The target pressure P in the vacuum chamber A And the material's dimensional data;

[0090] The analysis module is used to calculate at least the effective physical property parameters during the material sublimation process, the physical property parameters coupled with the temperature T at any time point during the material sublimation and drying process, and to solve the heat transfer model and mass transfer model involved in the material sublimation and drying process.

[0091] A storage module for storing data from the input module and the analysis module;

[0092] The output module is used to output at least the material sublimation curve, the historical distribution map of sublimation temperature, the historical distribution map of sublimation pressure, and the historical distribution map of sublimation phase field, and to predict the endpoint of material ice crystal sublimation.

[0093] In the above technical solution, COMSOL Multiphysics software is used to encapsulate the coded software based on Windows and Linux environments, enabling the visualization software to achieve cross-platform and offline operation without the need to install professional software, such as... Figures 1-3 as well as Figure 44 As shown, the parameter input options of the visualization software include options for setting the sublimation method, providing two sublimation modes: demolding and non-demolding. For demolding sublimation, a PP mold is selected. The visualization software interface also includes options for setting the axisymmetric shape of the material, providing four shapes: cylinder, cone, frustum, and hemisphere. It also includes input windows for the initial temperature, sublimation critical temperature, vacuum chamber ambient temperature, vacuum chamber shelf temperature, material thickness, material radius, material moisture content (mass fraction of water in the material), soluble solids content (mass fraction of soluble solids in the material), and coarse fiber content (mass fraction of coarse fiber in the material). The visualization software's graphical output window is designed as follows: it outputs the material sublimation curve, historical sublimation temperature distribution map, historical sublimation pressure distribution map, and historical phase field distribution map, and sets an adaptive resolution function for the window. The initial material temperature T0 represents the material temperature T corresponding to t=0.

[0094] The specific dimensional data of the material are as follows: When the material is a cylinder, cone, or frustum, the dimensional data includes the top radius, bottom radius, and thickness, in mm; when the material is a sphere, the dimensional data includes the radius, in mm.

[0095] Furthermore, the effective physical property parameters of the material refer to the effective physical property parameters during the sublimation and drying process of the material; the physical property parameters coupled with temperature T refer to the physical property parameters whose calculation formula includes the variable T.

[0096] The material sublimation curve can be a curve showing the change of the remaining ice crystal content over time. The historical distribution map of sublimation temperature represents the temperature distribution on the material surface at any given time point. The historical distribution map of sublimation pressure represents the pressure distribution on the material surface at any given time point. The historical distribution map of sublimation phase field represents the phase field distribution on the material surface at any given time point. The criterion for determining the sublimation endpoint is: when the remaining ice crystal content is 0, the time at which the sublimation occurs is the time required for sublimation.

[0097] A heat and mass transfer simulation device for a material sublimation process includes a memory and a processor. The memory is used to store information including program instructions, and the processor is used to control the execution of the program instructions. The program instructions are loaded and executed by the processor to implement the heat and mass transfer simulation method for the material sublimation drying process.

[0098] A computer-readable storage medium storing a computer program that, when executed by a processor, can perform a heat and mass transfer simulation method for implementing the material sublimation drying process.

[0099] The present invention has at least the following beneficial effects:

[0100] First, the heat and mass transfer simulation method for the material sublimation process provided by this invention fills the gap in the simulation of the material sublimation process and realizes precise control of the material sublimation process.

[0101] Secondly, the heat and mass transfer simulation method for the material sublimation process provided by this invention can accurately and reliably predict the sublimation endpoint of the material without destroying its original external structure by measuring the mass fraction of water, the mass fraction of soluble solids, and the mass fraction of coarse fiber in the material. This allows for precise control of the material sublimation drying cycle, achieving green and energy-saving material sublimation drying, and ultimately standardizing the production of material sublimation drying.

[0102] Third, the heat and mass transfer simulation method for the material sublimation process provided by this invention also couples the external dimensions of the material, which improves the accuracy of the heat and mass transfer simulation of the material sublimation process. It is beneficial to predict the temperature, pressure and phase change endpoint of the sublimation process in advance based on the differences in material properties and external dimensions, avoid over-drying or insufficient drying, and ensure the standardization of material sublimation production and the consistency of the quality of material sublimation products.

[0103] Fourth, the heat and mass transfer simulation method for the material sublimation process provided by this invention solves the problems of temperature monitoring during the sublimation process of materials (especially agricultural products), the difficulty in predicting the endpoint of material sublimation, and the difficulty in tracking the changes in the phase field during material sublimation.

[0104] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention.

[0105] Instruction manual illustrations

[0106] Figure 1 This refers to the function bar of the visualization software described in this invention;

[0107] Figure 2 This is the material attribute parameter input interface in the input field of the visualization software parameters of the present invention;

[0108] Figure 3 This is the working condition parameter input interface in the input field of the visualization software parameters of the present invention;

[0109] Figure 4 Several geometric models of the material described in this invention;

[0110] Figure 5 The geometric model (cylinder) of the material in Embodiment 1 of the present invention is shown, with the horizontal axis representing the diameter of the material and the vertical axis representing the thickness of the material.

[0111] Figure 6 This is a mesh model of the material in Embodiment 1 of the present invention, where the horizontal axis represents the material diameter and the vertical axis represents the material thickness;

[0112] Figure 7 The critical sublimation temperature of the material in Example 1 of this invention ( Figure 7 (Midpoint)

[0113] Figure 8 This is the material sublimation curve of Example 1 of the present invention;

[0114] Figure 9 This is a surface temperature distribution diagram of the material after 24 hours of sublimation in Example 1 of the present invention;

[0115] Figure 10 This is a diagram showing the ice crystal phase field distribution of the material after 24 hours of sublimation in Example 1 of the present invention.

[0116] Figure 11 Pressure distribution diagram of material sublimation for 24 hours in Example 1 of this invention;

[0117] Figure 12 The critical sublimation temperature of the material in Example 2 of the present invention (intersection in the figure);

[0118] Figure 13 This is the material sublimation curve of Example 2 of the present invention;

[0119] Figure 14 This is a surface temperature distribution diagram of the material after 24 hours of sublimation in Example 2 of the present invention;

[0120] Figure 15 This is a diagram showing the ice crystal phase field distribution of the material after 24 hours of sublimation in Example 2 of the present invention.

[0121] Figure 16 This is a pressure distribution diagram of the material after 24 hours of sublimation in Example 2 of the present invention;

[0122] Figure 17 The critical sublimation temperature of the material in Example 3 of the present invention (intersection in the figure);

[0123] Figure 18 This is the material sublimation curve of Example 3 of the present invention;

[0124] Figure 19 This is a surface temperature distribution diagram of the material after 24 hours of sublimation in Example 3 of the present invention;

[0125] Figure 20 This is a diagram showing the ice crystal phase field distribution of the material after 24 hours of sublimation in Example 3 of the present invention.

[0126] Figure 21 This is a pressure distribution diagram of the material after 24 hours of sublimation in Example 3 of the present invention;

[0127] Figure 22 This is the geometric model of the material in Embodiment 4 of the present invention, where both the horizontal and vertical axes represent the diameter of the material;

[0128] Figure 23 This is a mesh model of the material in Embodiment 4 of the present invention, where both the horizontal and vertical axes represent the diameter of the material;

[0129] Figure 24 The critical sublimation temperature of the material in Example 4 of the present invention (intersection in the figure);

[0130] Figure 25 This is the material sublimation curve of Example 4 of the present invention;

[0131] Figure 26 This is a surface temperature distribution diagram of the material after 24 hours of sublimation in Example 4 of the present invention;

[0132] Figure 27 This is a diagram showing the ice crystal phase field distribution of the material after 24 hours of sublimation in Example 4 of the present invention.

[0133] Figure 28 Pressure distribution diagram of material sublimation for 24 hours in Example 4 of this invention;

[0134] Figure 29 The critical sublimation temperature of the material in Example 5 of the present invention (intersection in the figure);

[0135] Figure 30 This is the material sublimation curve of Example 5 of the present invention;

[0136] Figure 31 This is a surface temperature distribution diagram of the material after 24 hours of sublimation in Example 5 of the present invention;

[0137] Figure 32 This is a diagram showing the ice crystal phase field distribution of the material after 24 hours of sublimation in Example 5 of the present invention.

[0138] Figure 33 This is a pressure distribution diagram of the material after 24 hours of sublimation in Example 5 of the present invention;

[0139] Figure 34 The critical sublimation temperature of the material in Example 6 of the present invention (intersection in the figure);

[0140] Figure 35 This is the material sublimation curve of Example 6 of the present invention;

[0141] Figure 36 This is a surface temperature distribution diagram of the material after 24 hours of sublimation in Example 6 of the present invention;

[0142] Figure 37 This is a diagram showing the ice crystal phase field distribution of the material after 24 hours of sublimation in Example 6 of the present invention.

[0143] Figure 38 This is a pressure distribution diagram of the material after 24 hours of sublimation in Example 6 of the present invention;

[0144] Figure 39 The critical sublimation temperature of the material in Example 7 of the present invention (intersection in the figure);

[0145] Figure 40 This is the material sublimation curve of Example 7 of the present invention;

[0146] Figure 41 This is a surface temperature distribution diagram of the material after 24 hours of sublimation in Example 7 of the present invention;

[0147] Figure 42 This is a diagram showing the ice crystal phase field distribution of the material after 24 hours of sublimation in Example 7 of the present invention.

[0148] Figure 43 This is a pressure distribution diagram of the material sublimation for 24 hours in Example 7 of the present invention;

[0149] Figure 44 This is the input interface for the critical sublimation temperature in the input field of the visualization software parameters of this invention. Detailed Implementation

[0150] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0151] <Example 1>

[0152] Geometric model of the material, such as Figure 4 As shown, the heat transfer simulation method for the sublimation process of a cylindrical material (radius 17 mm, height 10 mm) is as follows:

[0153] Step 1: Select the sublimation method: Sublimation without demolding;

[0154] Step 2: The freezing temperature T1 and initial temperature T0 of the material were both measured to be 233.15 K, and the mass fraction of moisture in the material X was measured. wThe mass fraction of soluble solids in the material is 89%. C (correspond Figure 2 The mass fraction of carbohydrates in the material is 10%, and the mass fraction of crude fiber in the material is X. F It is 1%;

[0155] Set the vacuum chamber ambient temperature T a (correspond Figure 3 The ambient temperature was 285.15 K, and the vacuum chamber shelf temperature was T. p (correspond Figure 3 The temperature of the middle partition is 243.15 K, and the vacuum is evacuated to the target pressure P. A =12 Pa (corresponding to) Figure 3 (pressure in the vacuum chamber), time t down =10.5 min;

[0156] Step 3, as follows Figure 5 As shown, the material geometry was generated using COMSOL Multiphysics software; the mesh size was set to finer, and the resulting geometric mesh of the synthesized material is as follows. Figure 6 As shown;

[0157] Step 4: Solve the heat transfer model of the material vacuuming process under the boundary conditions constrained by the material's geometric model to obtain the material's sublimation critical temperature T. f→g It is 243.47 K, such as Figure 7 As shown; Figure 7 The ordinate of the intersection of the two lines is the calculated critical sublimation temperature T of the material. f→g ;

[0158] Step 5: Solve the constructed heat transfer and mass transfer models of the material sublimation process under the boundary conditions constrained by the material's geometric model to obtain the sublimation curve, as shown below. Figure 8 As shown; Figure 8 The sublimation curve in the figure is the curve of the remaining ice crystal content changing with time. Sublimation ends when the remaining ice crystal content is 0.

[0159] Step 6: Set the material historical temperature time to 24 hours and obtain the material temperature historical distribution map as shown below. Figure 9 As shown; the material temperature history distribution map here refers to the material surface temperature distribution map after 24 hours of sublimation, and the same applies below;

[0160] Step 7: Set the phase field history time to 24 hours and obtain the phase field history distribution map of the material ice crystals as shown below. Figure 10 As shown; the material phase field history distribution diagram here refers to the ice crystal phase field history distribution diagram of the material after 24 hours of sublimation, and the same applies below;

[0161] Step 8: Set the pressure history time to 24 hours and obtain the material pressure history distribution map as shown below. Figure 11 As shown; the historical pressure distribution chart of the material here refers to the historical pressure distribution chart of the material 24 hours after sublimation, and the same applies below;

[0162] Step Nine, according to Figure 8 The results showed that the predicted sublimation endpoint of the material was 108.25 h, which was consistent with the actual result.

[0163] <Example 2>

[0164] Heat transfer simulation method for the sublimation process of a cylindrical material (radius 17mm, height 10mm):

[0165] Step 1: Select the sublimation method: Demolding sublimation;

[0166] Step 2: The freezing temperature and initial temperature of the material are 233.15 K, the mass fraction of moisture in the material is 89%, the mass fraction of soluble solids in the material is 10%, and the mass fraction of crude fiber in the material is 1%. The ambient temperature of the vacuum chamber is set to 285.15 K and the shelf temperature is set to 243.15 K. The time taken to evacuate to the target pressure of 12 Pa is 10.5 min.

[0167] Step 3: Use COMSOL Multiphysics software to generate the material geometry; set the mesh size to finer and synthesize the material's geometric mesh;

[0168] Step 4: Solve the heat transfer model of the material vacuuming process under the boundary conditions constrained by the material's geometric model, obtaining a sublimation temperature of 245.24 K. Figure 12 As shown, Figure 12 The vertical axis of the midpoint is the sublimation temperature;

[0169] Step 5: Solve the constructed heat and mass transfer model of the material sublimation process under the boundary conditions constrained by the geometric model of the material to obtain the sublimation curve, as shown below. Figure 13 As shown;

[0170] Step 6: Set the material historical temperature time to 24 hours and obtain the material temperature historical distribution map as shown below. Figure 14 As shown;

[0171] Step 7: Set the phase field history time to 24 hours and obtain the phase field history distribution map of the material ice crystals as shown below. Figure 15 As shown;

[0172] Step 8: Set the pressure history time to 24 hours and obtain the material pressure history distribution map as shown below. Figure 16 As shown;

[0173] Step Nine, according to Figure 13 The results showed that the predicted sublimation endpoint of the material was 87.90 h, which was consistent with the actual result.

[0174] <Example 3>

[0175] Heat transfer simulation method for the sublimation process of cylindrical material (radius 17 mm, height 10 mm):

[0176] Step 1: Select the sublimation method: Sublimation without demolding;

[0177] Step 2: The freezing temperature and initial temperature of the material are 233.15 K, the mass fraction of moisture in the material is 79%, the mass fraction of soluble solids in the material is 20%, and the mass fraction of crude fiber in the material is 1%. The sublimation chamber ambient temperature is set to 285.15 K and the shelf temperature is set to 243.15 K. The vacuuming process to the target pressure of 12 Pa takes 10.5 min.

[0178] Step 3: Use COMSOL Multiphysics software to generate the material geometry; set the mesh size to finer and synthesize the material's geometric mesh;

[0179] Step 4: Solve the heat transfer model of the material vacuuming process under the boundary conditions constrained by the material's geometric model, obtaining a sublimation temperature of 243.75 K. Figure 17 As shown;

[0180] Step 5: Solve the constructed heat and mass transfer model of the material sublimation process under the boundary conditions constrained by the geometric model of the material to obtain the sublimation curve, as shown below. Figure 18 As shown;

[0181] Step 6: Set the material historical temperature time to 24 hours and obtain the material temperature historical distribution map as shown below. Figure 19 As shown;

[0182] Step 7: Set the phase field history time to 24 hours and obtain the phase field history distribution map of the material ice crystals as shown below. Figure 20 As shown;

[0183] Step 8: Set the pressure history time to 24 hours and obtain the material pressure history distribution map as shown below. Figure 21 As shown;

[0184] Step Nine, according to Figure 18 The results showed that the predicted sublimation endpoint of the material was 118.72 h, which was consistent with the actual result.

[0185] <Example 4>

[0186] Heat transfer simulation method for the sublimation process of hemispherical material (radius 15 mm):

[0187] Step 1: Select the sublimation method: Demolding sublimation;

[0188] Step 2: The freezing temperature and initial temperature of the material are 233.15 K, the mass fraction of moisture in the material is 89%, the mass fraction of soluble solids in the material is 10%, and the mass fraction of crude fiber in the material is 1%. The sublimation chamber ambient temperature is set to 285.15 K and the shelf temperature is set to 243.15 K. The vacuuming process to the target pressure of 12 Pa takes 10.5 min.

[0189] Step 3: Use COMSOL Multiphysics software to generate the material geometry, such as... Figure 22 As shown; set the mesh size to finer, and the geometric mesh of the synthetic material is as follows. Figure 23 As shown;

[0190] Step 4: Solve the heat transfer model of the material vacuuming process under the boundary conditions constrained by the material's geometric model, obtaining a sublimation temperature of 244.94 K. Figure 24 As shown;

[0191] Step 5: Solve the constructed heat and mass transfer model of the material sublimation process under the boundary conditions constrained by the geometric model of the material to obtain the sublimation curve, as shown below. Figure 25 As shown;

[0192] Step 6: Set the material historical temperature time to 24 hours and obtain the material temperature historical distribution map as shown below. Figure 26 As shown;

[0193] Step 7: Set the phase field history time to 24 hours and obtain the phase field history distribution map of the material ice crystals as shown below. Figure 27 As shown;

[0194] Step 8: Set the pressure history time to 24 hours and obtain the material pressure history distribution map as shown below. Figure 28 As shown;

[0195] Step Nine, according to Figure 25 The results showed that the predicted sublimation endpoint of the material was 73.795 h, which was consistent with the actual result.

[0196] <Example 5>

[0197] Heat transfer simulation method for the sublimation process of cylindrical material (radius 17 mm, height 10 mm):

[0198] Step 1: Select the sublimation method: Demolding sublimation;

[0199] Step 2: The freezing temperature and initial temperature of the material are 233.15 K, the mass fraction of moisture in the material is 89%, the mass fraction of soluble solids in the material is 10%, and the mass fraction of crude fiber in the material is 1%. The sublimation chamber ambient temperature is set to 285.15 K and the shelf temperature is set to 253.15 K. The vacuuming process to the target pressure of 12 Pa takes 10.5 min.

[0200] Step 3: Use COMSOL Multiphysics software to generate the material geometry; set the mesh size to finer and synthesize the material's geometric mesh;

[0201] Step 4: Solve the heat transfer model of the material vacuuming process under the boundary conditions constrained by the material's geometric model, obtaining a sublimation temperature of 247.09 K. Figure 29 As shown;

[0202] Step 5: Solve the constructed heat and mass transfer model of the material sublimation process under the boundary conditions constrained by the geometric model of the material to obtain the sublimation curve, as shown below. Figure 30 As shown;

[0203] Step 6: Set the material historical temperature time to 24 hours and obtain the material temperature historical distribution map as shown below. Figure 31 As shown;

[0204] Step 7: Set the phase field history time to 24 hours and obtain the phase field history distribution map of the material ice crystals as shown below. Figure 32 As shown;

[0205] Step 8: Set the pressure history time to 24 hours and obtain the material pressure history distribution map as shown below. Figure 33 As shown;

[0206] Step Nine, according to Figure 30 The results showed that the predicted sublimation endpoint of the material was 37.302 hours, which was consistent with the actual result.

[0207] <Example 6>

[0208] Heat transfer simulation method for the sublimation process of hemispherical material (radius 15 mm):

[0209] Step 1: Select the sublimation method: Demolding sublimation;

[0210] Step 2: The freezing temperature of the material is -196℃, the initial temperature is 233.15 K, the mass fraction of moisture in the material is 89%, the mass fraction of soluble solids in the material is 10%, and the mass fraction of crude fiber in the material is 1%. The sublimation chamber ambient temperature is set to 285.15 K and the shelf temperature is set to 243.15 K. The vacuum is evacuated to the target pressure of 12 Pa in 10.5 min.

[0211] Step 3: Use COMSOL Multiphysics software to generate the material geometry; set the mesh size to finer and synthesize the material's geometric mesh;

[0212] Step 4: Solve the heat transfer model of the material vacuuming process under the boundary conditions constrained by the material's geometric model, obtaining a sublimation temperature of 244.94 K. Figure 34 As shown;

[0213] Step 5: Solve the constructed heat and mass transfer model of the material sublimation process under the boundary conditions constrained by the geometric model of the material to obtain the sublimation curve, as shown below. Figure 35 As shown;

[0214] Step 6: Set the material historical temperature time to 24 hours and obtain the material temperature historical distribution map as shown below. Figure 36 As shown;

[0215] Step 7: Set the phase field history time to 24 hours and obtain the phase field history distribution map of the material ice crystals as shown below. Figure 37 As shown;

[0216] Step 8: Set the pressure history time to 24 hours and obtain the material pressure history distribution map as shown below. Figure 38 As shown;

[0217] Step Nine, according to Figure 35 The results showed that the predicted sublimation endpoint of the material was 75.426 h, which was consistent with the actual result.

[0218] <Example 7>

[0219] Heat transfer simulation method for the sublimation process of a cylindrical material (radius 17mm, height 10mm):

[0220] Step 1: Select the sublimation method: Sublimation without demolding;

[0221] Step 2: The freezing temperature and initial temperature of the material are 233.15 K, the mass fraction of moisture in the material is 89%, the mass fraction of soluble solids in the material is 10%, and the mass fraction of crude fiber in the material is 1%. The sublimation chamber ambient temperature is set to 285.15 K and the shelf temperature is set to 243.15 K. The vacuum is evacuated to the target pressure of 12 Pa in 15 minutes.

[0222] Step 3: Use COMSOL Multiphysics software to generate the material geometry; set the mesh size to finer and synthesize the material's geometric mesh;

[0223] Step 4: Solve the heat transfer model of the material vacuuming process under the boundary conditions constrained by the material's geometric model, obtaining a sublimation temperature of 243.59 K. Figure 39 As shown;

[0224] Step 5: Solve the constructed heat and mass transfer model of the material sublimation process under the boundary conditions constrained by the geometric model of the material to obtain the sublimation curve, as shown below. Figure 40 As shown;

[0225] Step 6: Set the material historical temperature time to 24 hours and obtain the material temperature historical distribution map as shown below. Figure 41 As shown;

[0226] Step 7: Set the phase field history time to 24 hours and obtain the phase field history distribution map of the material ice crystals as shown below. Figure 42 As shown;

[0227] Step 8: Set the pressure history time to 24 hours and obtain the material pressure history distribution map as shown below. Figure 43 As shown;

[0228] Step 8, according to Figure 40 The results showed that the predicted sublimation endpoint of the material was 106.64 h, which was consistent with the actual result.

[0229] By comparing the data results of Examples 1 to 7, it can be clearly found that the sublimation endpoint of the material is affected by the material's external dimensions, sublimation method, and the proportion of each component in the material.

[0230] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for simulating heat transfer during the sublimation drying process of materials, characterized in that, Includes the following steps: Step 1: Based on the material's composition parameters, obtain the crude fiber volume fraction V of the material during the sublimation drying process. F soluble solids volume fraction V C Ice crystal integral number Vi, porosity α; Step 2: Based on the parameters in Step 1, obtain the critical sublimation temperature T of the material under vacuum during the vacuuming process. f→g K; when the geometric mean temperature of the material is greater than or equal to the sublimation critical temperature T. f→g At that time, sublimation occurs; Step 3: Predict the sublimation endpoint of the material using the following calculation steps: S1, Calculate the ice saturation S of the material at the current time and space. i and water vapor saturation S g S2. Based on the parameters in step one and step S1, calculate the effective thermal conductivity γ of the porous medium of the material under the current time and space conditions. s Effective density ρ of porous media s Effective specific heat capacity Cp of porous media s The effective thermal conductivity γ of the sublimation phase f Effective density of sublimation phase ρ f Sublimation phase effective specific heat capacity Cp f S3. Based on the parameters in Step 1 and Steps S1-S2, calculate the sublimation rate source term of the material in the current time and space. ; S4. Based on the parameters from steps one and S1 to S3, calculate the water vapor pressure P and water vapor density ρ of the material in the current time and space. g 1. Water vapor velocity μ; S5. Calculate the material temperature in the current time and space based on the parameters in steps 1 to 2 and steps S1 to S4; S6. Use the material temperature in the current time and space obtained in S5 as the input parameter in S1, and repeat steps S1 to S5 to solve for the material temperature in the next time and space; S7. Repeat steps S1 to S6 to finally calculate the ice saturation S of the material. i The spatiotemporal distribution field; when the ice saturation S of the material at any point... i When all values ​​are 0, the sublimation process reaches its endpoint.

2. The heat transfer simulation method for the material sublimation drying process as described in claim 1, characterized in that, In step two, the critical sublimation temperature T of the material... f→g Obtain it in the following way: A1. Determine the geometric mean temperature T of the material during the vacuuming process. mean The curve that changes over time yields tT mean The curve, where t is any time point during the vacuuming process; where T mean Solve it in the following way: A11. Construct a heat transfer model for the material during the vacuuming process, as follows: ； ρ eff The effective density of a material is expressed in kg / m³. 3 ; Cp eff The effective specific heat capacity of the material is expressed in J / (kg·K). γ eff The effective thermal conductivity of a material is expressed in W / m·K. Cp F The value represents the specific heat capacity of the crude fiber in the material, J / (kg·K). Cp C The specific heat capacity of soluble solids in a material is expressed in J / (kg·K). Cp i The specific heat capacity of ice in the material is expressed in J / (kg·K). γ F This represents the thermal conductivity of the coarse fibers in the material, expressed in W / (m·K). γ C It represents the thermal conductivity of the soluble solids in a material, in W / (m·K); γ i This represents the thermal conductivity of the material, expressed in W / (m·K). Q1 represents the heat radiated by the environment to the material, in J; Q2 represents the heat transferred from the shelf to the material, in J; Q3 represents the heat transferred to the material by gas convection, in J; T a Indicates the ambient temperature of the vacuum chamber, in K; T p This indicates the temperature of the vacuum chamber shelf, in K; h p This indicates the heat transfer coefficient of the shelf, 26 W / (m²). 2 ·K); h a This represents the gas convective heat transfer coefficient, 1.54 × 10⁻⁶. −3 ×P c W / (m 2 ·K); This indicates the surface emissivity factor, which is determined during demolding and vacuuming. =0.97, when vacuuming without demolding. =0.2; σ represents the Stevie-Boltzmann constant, 5.676 × 10⁻⁶. −8 W·m −2 ·K −4 ; T represents the temperature at any point in time during the sublimation and drying process of the material, in K; A12. Using the above heat transfer model, the spatiotemporal field of the material temperature during the vacuuming process is obtained; during the vacuuming process, the average temperature of each point inside the material at each moment is taken to obtain the geometric mean temperature T of the material at each moment. mean , thereby obtaining tT mean curve; A2. Determine the sublimation temperature T corresponding to the vacuum chamber pressure during the vacuuming process. 升 , obtain tT 升 curve; ； P c The pressure in the vacuum chamber is expressed in Pa and P. c =1.01×10 5 +(P A –1.01×10 5 )×t / t down ;P A The target pressure of the vacuum chamber is expressed in Pa; t down This indicates that the pressure in the vacuum chamber decreases from atmospheric pressure to the target pressure P. A The time taken, min; ΔH f→g Indicates latent heat of sublimation, J / kg; ;T t The triple point temperature is 273.15 K. A3、tT mean Curve and tT 升 The temperature corresponding to the intersection of the curves is the critical sublimation temperature T of the material. f→g .

3. The heat transfer simulation method for the material sublimation drying process as described in claim 2, characterized in that, Step three specifically includes the following steps: S1. Calculate the ice saturation S of the material at the current time and space. i and water vapor saturation S g , ;S i =1-S g ; ΔT f→g =0.5K; T is the temperature of the material in the previous time space, in K; S2. Based on the parameters in Step 1 and Step S1, obtain the effective physical property parameters of the material under the current time and space. The effective physical property parameters include the effective thermal conductivity γ of the porous medium. s Effective density ρ of porous media s Effective specific heat capacity Cp of porous media s The effective thermal conductivity γ of the sublimation phase f Effective density of sublimation phase ρ f Sublimation phase effective specific heat capacity Cp f ; S3. Based on the parameters in Step 1 and Steps S1-S2, calculate the sublimation rate source term of the material in the current time and space. kg / (m 3 s), ; S4. Based on the parameters from steps one and S1 to S3, construct a mass transfer model. Using the mass transfer model, calculate the water vapor pressure P and water vapor density ρ of the material at the current time and space. g The water vapor velocity μ; the mass transfer model is: ； D eff The effective diffusion rate of water vapor is represented by m. 2 / s; κ represents the Darcy permeability of water vapor, m 2 ; pore represents the average pore size of the material, in μm; pore = 1.47 + 7.44 e ( T1+ 196) / 85.35 , μm, where T1 represents the freezing temperature; M g This represents the molar mass of water vapor, 18 g / mol. R represents the ideal gas constant, 8.314 J / (mol·K); μ g The viscosity of water vapor is expressed in kg / (m∙s). S5. Based on the parameters from steps one to two and steps S1 to S4, construct a heat transfer model. Using this model, calculate the material temperature T at the current time and space. The heat transfer model is as follows: ； Cp g This represents the specific heat capacity of water vapor, J / kg / K, 1674.7 J / kg / K; γ g The value represents the thermal conductivity of water vapor, W / m·K, 0.025 W / m / K; S6. Using the material temperature T obtained in S5 under the current time and space as the input parameter in S1, repeat steps S1 to S5 to solve for the material temperature T under the next time and space. S7. Repeat steps S1 to S6 above to finally calculate the ice saturation S of the material during sublimation. i The spatiotemporal distribution field; based on ice saturation S i The spatiotemporal distribution field, when the ice saturation S of the material at any point... i When all values ​​are 0, the sublimation process reaches its endpoint.

4. The heat transfer simulation method for the material sublimation drying process as described in claim 3, characterized in that, In step one, the methods for obtaining each parameter are as follows: crude fiber volume fraction V F ,%V F =(X F / ρ F ) / (X F / ρ F +X w / ρ i +X c / ρ C ); Soluble solids volume fraction V C ,%V C =(Xc / ρ C ) / (X F / ρ F +Xw / ρ i +Xc / ρ C ); Ice crystal integral V i ,%V i =(1−V F -V C ); Porosity ɛ, %, ɛ = 1 − V F -V C ; Among them, X W This indicates the mass fraction of moisture in a material, expressed as % . X C This indicates the mass fraction of soluble solids in a material, expressed as % . X F This indicates the mass fraction of crude fiber in the material, expressed as % . ρ i This indicates the density of ice, in kg / m³. 3 , ρ i =916.89−0.1307×T; ρ C This indicates the density of the soluble solids in the material, expressed in kg / m³. 3 , ρ C =1599.1−0.31046×T; ρ F This indicates the coarse fiber density of the material, in g / m³. 3 , ρ F =1311.5−0.36589×T.

5. The heat transfer simulation method for the material sublimation drying process as described in claim 2, characterized in that, In step A1: The specific heat capacity Cp of the crude fiber of the material F =1845.9+1.8306×T×(−0.0046509)×T 2 ; Specific heat capacity Cp of soluble solids in material C =1548.8+1.9625×T×(−0.0059399)×T 2 ; Specific heat capacity of ice in material Cp i =2062.3+6.0769×T; The thermal conductivity γ of the coarse fiber of the material F =0.18331+0.0012497×T−3.1683×10 −6 ×T 2 ; Thermal conductivity γ of soluble solids in material C =0.20141+0.0013874×T−4.3312×10 −6 ×T 2 ; The thermal conductivity γ of the material ice i =2.2196−6.2489×10 −3 ×T+1.0154×10 −4 ×T 2 .

6. The heat transfer simulation method for the material sublimation drying process as described in claim 3, characterized in that, In step S2: The effective thermal conductivity γ of porous matrix S W / (m·K), γ S =(V F ×γ F ) / (V F +S g ×V C )+(S g ×V C ×γ C ) / (V F +S g ×V C ); Effective density ρ of porous matrix S kg / m 3 , ρ S =(V F ×ρ F ) / (V F +S g ×V C )+ (S g ×V C ×ρ C ) / (V F +S g ×V C ); Effective specific heat capacity Cp of porous matrix S J / kg / K, Cp S =(Cp F ×X F ) / (X F +S g ×X C )+(S g ×Cp C ×X C ) / (X F +Sg×X C ); The effective thermal conductivity γ of the sublimation phase f W / (mK), γ f =(V i ×γ i ) / (V i +V C )+(S i ×V C ×γ C ) / (V i +V C ); Sublimation phase effective density ρ f kg / m 3 , ρ f =(V i ×ρ i ) / (V i +V C )+(S i ×V C ×ρ C ) / (V i +V C ); Sublimation phase effective specific heat capacity Cp f J / kg / K, Cp f =(S i ×Cp i ×X i ) / (X i +X C )+(S i ×Cp C ×X C ) / (X i +X C ).

7. The heat transfer simulation method for the material sublimation drying process as described in claim 3, characterized in that, It also includes a step of further coupling the mass transfer model and heat transfer model of the material sublimation process obtained in steps S4 and S5 with the axisymmetric material shape, so as to construct heat transfer and mass transfer models of the sublimation process of materials with different axisymmetric shapes. Specifically, the material size is obtained using COMSOL Multiphysics software, the geometric model of the material is constructed and the mesh is refined, and the mass transfer model in step S4 and the heat transfer model in step S5 are solved under the boundary conditions constrained by the geometric model of the material.

8. A heat transfer simulation system based on the heat transfer simulation method for the material sublimation drying process as described in claim 7, characterized in that, include: The input module is used to input at least the mass fraction X of moisture in the material. W Mass fraction of soluble solids in the material X C Mass fraction of crude fiber in the material X F The initial temperature of the material T0, the freezing temperature of the material T1, and the ambient temperature of the vacuum chamber T a Vacuum chamber shelf temperature T p The target pressure P of the vacuum chamber A And the material's dimensional data; The analysis module is used to calculate at least the effective physical property parameters during the material sublimation process, the physical property parameters coupled with the temperature T at any time point during the material sublimation and drying process, and to solve the heat transfer model and mass transfer model involved in the material sublimation and drying process. A storage module for storing data from the input module and the analysis module; The output module is used to output at least the material sublimation curve, the historical distribution map of sublimation temperature, the historical distribution map of sublimation pressure, and the historical distribution map of sublimation phase field, and to predict the endpoint of material ice crystal sublimation.

9. A heat and mass transfer simulation device for the sublimation process of materials, characterized in that, include: The system includes a memory and a processor, wherein the memory is used to store information including program instructions, and the processor is used to control the execution of the program instructions, which are loaded and executed by the processor to implement the heat and mass transfer simulation method for the material sublimation drying process as described in any one of claims 1 to 6.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it can perform a heat and mass transfer simulation method for the material sublimation drying process described in any one of 1 to 6.

Images