Method and device for predicting material state in fresh-keeping process and vacuum cooling device

Abstract

The invention provides a method for predicting a material state in a fresh-keeping process. The method comprises the following steps: establishing a geometric model of a material according to the shape of the material; determining material parameters of the geometric model according to a fresh-keeping process; constructing a physical field according to the geometric model and the material parameters; a control equation is constructed for the physical field, a heat transfer control equation in the fresh-keeping process is constructed through heat transfer in the materials and heat transfer between the materials and media, and a mass transfer control equation in the fresh-keeping process is constructed through the substance diffusion condition of the materials in the environment; initial conditions, boundary conditions and physical field parameters are set for the physical field; performing grid division on the geometric model; and solving the control equation and post-processing the solving result. The invention further provides a device for predicting the material state in the preservation process and a vacuum cooling device.

Description

Technical Field

[0001] The present invention relates to the field of food processing, and particularly to a method and device for predicting the state of materials during the preservation process. Background Art

[0002] Vacuum cooling is an efficient and rapid method for preserving materials. The principle of vacuum cooling is to use the latent heat caused by the phase change of water to achieve temperature reduction. Under the condition of constant temperature at normal temperature, reducing the pressure will cause water to change from liquid to gas. The latent heat absorbed by the evaporation of water in the material mainly comes from the sensible heat of the material, and the specific heat of water is larger than that of most other liquids, thereby achieving rapid cooling of the material.

[0003] However, since the vacuum chamber needs to be strictly sealed during the cooling process, it is difficult to directly monitor the food state of the cooled materials. Therefore, the control of the vacuum cooling process is inaccurate, resulting in a decline in the quality of the materials. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention discloses a method for predicting the state of materials during the preservation process, including the following steps:

[0005] Establish a geometric model of the material according to the shape of the material;

[0006] Determine the material parameters of the geometric model according to the preservation process;

[0007] Construct a physical field according to the geometric model and the material parameters;

[0008] Construct a control equation for the physical field, wherein a heat transfer control equation for the preservation process is constructed through the heat transfer inside the material and the heat transfer between the material and the medium, and a mass transfer control equation for the preservation process is constructed through the mass diffusion of the material in the environment;

[0009] Set initial conditions, boundary conditions and physical field parameters for the physical field;

[0010] Perform mesh division on the geometric model;

[0011] Solve the control equation and post-process the solution results.

[0012] In an embodiment of the foregoing method of the present invention, the step of constructing a heat transfer control equation for the preservation process through the heat transfer inside the material and the heat transfer between the material and the medium further includes:

[0013] Construct a heat transfer control equation inside the material according to the conservation of energy of heat transfer in the medium;

[0014] Construct a heat transfer control equation between the material and the environment through the heat transfer situation of the boundary of the material in the medium.

[0015] In an embodiment of the foregoing method of the present invention, the step of constructing a mass transfer control equation during the preservation process by the mass diffusion of the material in the environment further includes:

[0016] Construct the mass transfer control equation of the material in the environment according to the law of mass transfer from a high-concentration region to a low-concentration region.

[0017] In an embodiment of the foregoing method of the present invention, the step of constructing a heat transfer control equation inside the material according to the energy conservation of heat transfer in the medium further includes:

[0018] Construct the heat transfer control equation inside the material using Fourier's law of heat conduction:

[0019] where ρ represents density, with the unit kg / m 3 , C P represents the constant-pressure heat capacity, with the unit J / (kg / K), J is joule, K is Kelvin temperature, T represents the material temperature, with the unit K, t represents time, with the unit s, represents the vector differential operator, q represents the net heat flux density vector, with the unit W / m 2 , W is watt, Q represents the internal heat source, W / m 3 ;

[0020] where, represents the evaporation rate of water, with the unit kg / (m 3 *s), ΔH vap represents the latent heat of evaporation of water, with the unit J / kg;

[0021] where k vap represents the evaporation rate constant, with the unit 1 / s, ρ L represents the liquid-phase density, with the unit kg / m 3 , p * represents the saturation vapor pressure, with the unit Pa, p G represents the pressure in the vacuum chamber, with the unit Pa; and,

[0022] p * = 10 A-B / (C+T) , where A, B, and C are constants, and T represents the material temperature, with the unit K.

[0023] In an embodiment of the foregoing method of the present invention, the step of constructing a heat transfer control equation between the material and the environment by the heat transfer of the material boundary in the medium further includes:

[0024] The heat transfer control equation between the material and the environment is constructed using Newton's law of cooling:

[0025] q = h(T ext - T), where q represents the net heat flux density vector on the material boundary, with the unit of W / m 2 , h represents the heat transfer coefficient on the boundary, with the unit of W / (m 2 *K), T ext represents the external environment temperature, with the unit of K, and T represents the material temperature, with the unit of K.

[0026] In an embodiment of the foregoing method of the present invention, the steps of constructing the mass transfer control equation of the material in the environment according to the law of mass transfer from a high-concentration region to a low-concentration region further include:

[0027] The mass transfer control equation of the material in the environment is constructed using Fick's second law of diffusion:

[0028] where θ L represents the volume fraction of the liquid phase, and D L represents the apparent liquid diffusion coefficient, with the unit of m2 / s;

[0029] where α represents a proportionality constant, represents the residual saturation.

[0030] In an embodiment of the foregoing method of the present invention, the steps of solving the control equation and post-processing the solution results further include:

[0031] Set the solver to transient;

[0032] Set the output time step according to the requirements of the preservation process;

[0033] Set the plotting group to plot the data results according to the solution results of the control equation.

[0034] The present invention also provides a device for predicting the state of a material during the preservation process, which is used to implement the foregoing method, and includes:

[0035] A geometric model construction module that establishes the geometric model of the material according to the shape of the material;

[0036] A material parameter module that determines the material parameters of the geometric model according to the preservation process;

[0037] A physical field construction module that constructs a physical field according to the geometric model and the material parameters, and the physical field construction module further includes:

[0038] A control equation construction module constructs control equations for the physical field, wherein a heat transfer control equation for the preservation process is constructed through heat transfer within the material and heat transfer between the material and the medium, and a mass transfer control equation for the preservation process is constructed based on the mass diffusion of the material in the environment;

[0039] A physical field setting module sets initial conditions, boundary conditions, and physical field parameters for the physical field;

[0040] A mesh generation module performs mesh generation on the geometric model;

[0041] A solution and post-processing module solves the control equations and post-processes the solution results.

[0042] The present invention also provides a vacuum cooling device, comprising:

[0043] A vacuum chamber for providing a vacuum environment for the material;

[0044] A vacuum unit, including a vacuum pump and a vacuum valve connected to the vacuum pump, wherein the vacuum pump and the vacuum valve are used to provide a vacuum environment for the vacuum chamber;

[0045] A cooling unit, connected to the vacuum chamber, for providing cooling water;

[0046] A control unit, connected to the vacuum pump and the cooling unit;

[0047] The aforementioned device for predicting the state of the material during the preservation process, wherein the device for predicting the state of the material during the preservation process is connected to the control unit.

[0048] The present invention also provides a storage medium for storing a computer control program, and the computer control program is used to execute the steps of any of the foregoing methods. [[ID=#31]]

[0049] A method, device, and vacuum cooling device for predicting the state of a material during a preservation process proposed by the present invention construct a geometric model of the material and the material parameters of the geometric model, and construct a physical field based on the geometric model and the material parameters. Control equations are constructed for the physical field, wherein a heat transfer control equation for the preservation process is constructed through heat transfer within the material and heat transfer between the material and the medium, and a mass transfer control equation for the preservation process is constructed based on the mass diffusion of the material in the environment. The control equations are solved to obtain a simulation result of the state of the material during the preservation process. Based on this simulation result, the preservation process can be precisely controlled to better maintain the quality of the material. Description of the Drawings

[0050] Figure 1 It is a schematic flowchart of the method for predicting the state of a material during a preservation process in an embodiment of the present invention;

[0051] Figure 2 It is the two-dimensional axisymmetric model diagram of the material in the embodiment of the present invention;

[0052] Figure 3 It is the grid division diagram of the material in the embodiment of the present invention;

[0053] Figure 4 It is the temperature distribution diagram of the material in the embodiment of the present invention;

[0054] Figure 5 It is the moisture distribution diagram of the material in the embodiment of the present invention;

[0055] Figure 6 It is the measured temperature and simulated temperature change curves of the material during the vacuum cooling process in the embodiment of the present invention;

[0056] Figure 7 It is the measured moisture content and simulated temperature change curves of the material during the vacuum cooling process in the embodiment of the present invention

[0057] Figure 8 It is the block diagram of the device for predicting the state of the material during the preservation process in the embodiment of the present invention;

[0058] Figure 9 It is the block diagram of the vacuum cooling device in the embodiment of the present invention.

[0059] Among them, reference numerals:

[0060] 1: Two-dimensional axisymmetric model

[0061] 21: Grid

[0062] 10: Device for predicting the state of the material during the preservation process

[0063] 11: Geometric model construction module

[0064] 12: Material parameter module

[0065] 13: Physical field construction module

[0066] 14: Control equation construction module

[0067] 15: Physical field setting module

[0068] 16: Grid division module

[0069] 17: Solving and post-processing module

[0070] 100: Vacuum cooling device

[0071] 110: Vacuum chamber

[0072] 120: Vacuum unit

[0073] 121: Vacuum pump

[0074] 122: Vacuum valve

[0075] 130: Cooling unit

[0076] 140: Control unit

[0077] S1 - S7: Steps Detailed implementation manners

[0078] The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments to further understand the purpose, solutions and beneficial technical effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0079] It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non - exclusive inclusion, so that a process, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, article or device. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or device including the said element.

[0080] In the specification and the appended claims, certain terms are used to refer to specific components or parts. Those of ordinary skill in the art should understand that different nouns or terms may be used by technical users or manufacturers to refer to the same component or part. The specification and the appended claims do not use the difference in names as a way to distinguish components or parts, but use the difference in the functions of components or parts as the criterion for distinction.

[0081] In the present invention, terms such as "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation.

[0082] Moreover, in addition to being used to represent orientation or positional relationships, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0083] In addition, the terms "installed", "set up", "provided with", "connected", and "linked" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, components, or parts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0084] Vacuum cooling: At normal atmospheric pressure (1 atmosphere), the boiling point of water is 100 °C. When the air pressure decreases, the boiling point of water also decreases accordingly. For example, at 0.01 atmospheres, the boiling point of water can be reduced to about 0 °C. Vacuum cooling accelerates heat dissipation by reducing the ambient air pressure and causing water to boil at a lower temperature. When water changes from a liquid state to a gaseous state (evaporation), it absorbs a large amount of heat. This is because evaporation is an endothermic process that requires energy to overcome the intermolecular attraction. In a vacuum environment, water molecules are more likely to evaporate from the liquid state to the gaseous state, thereby taking away more heat and achieving rapid cooling. Since the evaporation rate in a vacuum environment is much higher than that at normal atmospheric pressure, the temperature of food can be rapidly reduced. This rapid cooling method can effectively reduce the growth of microorganisms and chemical reactions in food, thereby extending the shelf life of food.

[0085] The use of vacuum cooling has two requirements for the material itself: the material should have a large specific surface area and porosity; partial water loss of the material will not cause serious quality impacts. Currently, in the food industry, vacuum cooling is widely used in two aspects: removing the field heat of fruits and vegetables and precooling cooked meat products.

[0086] Since the vacuum chamber needs to be strictly sealed during the cooling process, it is difficult to directly monitor the food state of the cooled material. Therefore, the control of the vacuum cooling process is inaccurate, resulting in a decline in the quality of the material. To solve this technical problem, as Figure 1 shown, the present invention discloses a method for predicting the state of materials during the preservation process, including the following steps:

[0087] Step S1: Establish a geometric model of the material according to the shape of the material;

[0088] Step S2: Determine the material parameters of the geometric model according to the preservation process;

[0089] Step S3: Construct a physical field according to the geometric model and the material parameters;

[0090] Step S4: Construct control equations for the physical fields, where a heat transfer control equation for the preservation process is constructed through heat transfer within the material and heat transfer between the material and the medium, and a mass transfer control equation for the preservation process is constructed based on the mass diffusion of the material in the environment;

[0091] Step S5: Set initial conditions, boundary conditions, and physical field parameters for the physical fields;

[0092] Step S6: Mesh the geometric model;

[0093] Step S7: Solve the control equations and post-process the solution results.

[0094] As Figure 2 shown, in one embodiment, in Step S1, a geometric model of the material is established according to parameters such as the length, width, and height of the material placed in the vacuum chamber. In one embodiment, the geometric model of the material can be established in COMSOL simulation software or other modeling software. It should be noted that the simulation software used in the present invention is COMSOL, and other similar simulation software can also be used to implement the method of the present invention, which is not limited thereto. In one embodiment, the established geometric model of the material abstracts the three-dimensional geometric model into a two-dimensional axisymmetric model 1.

[0095] In one embodiment, the material parameters determined in Step S2 include density, constant pressure heat capacity, and thermal conductivity. Since food materials are mostly porous medium materials, the material properties need to be divided into solid phase, liquid phase, and gas phase according to the different phases. The above parameters are obtained through measurement and data query as shown in Table 1. Table 1 shows the material property parameters of the materials used in the experiment. For other types of materials, their relevant property parameters need to be measured and obtained through data query.

[0096] Table 1 Material Property Details

[0097]

[0098]

[0099] In one embodiment, the steps of constructing a heat transfer control equation for the preservation process through heat transfer within the material and heat transfer between the material and the medium further include:

[0100] Construct a heat transfer control equation within the material based on the conservation of energy of heat transfer in the medium;

[0101] Construct a heat transfer control equation between the material and the environment by the heat transfer situation of the material boundary in the medium. Analyze the heat transfer of the material in the environment using the above method and establish a control equation to describe the dynamic heat transfer process of the material on different time scales. The temperature change law of the material inside and at the boundary over time can be obtained, so as to predict the temperature distribution and heat transfer situation of the material at different time points, with strong predictability.

[0102] In one embodiment, the steps of constructing a mass transfer control equation during the preservation process by the mass diffusion of the material in the environment further include:

[0103] Construct a mass transfer control equation of the material in the environment according to the law of mass transfer from the high-concentration region to the low-concentration region. This method can describe the dynamic mass transfer process of the material on different time scales. By solving the mass transfer control equation, the concentration change law of the material inside and at the boundary over time can be obtained, so as to predict the concentration distribution and mass transfer situation of the material at different time points, with strong predictability.

[0104] In one embodiment, the steps of constructing an internal heat transfer control equation of the material according to the energy conservation of heat transfer in the medium further include:

[0105] Construct an internal heat transfer control equation of the material using Fourier's law of heat conduction:

[0106] where ρ represents density, with the unit kg / m 3 , C P represents the constant-pressure heat capacity, with the unit J / (kg / K), J is joule, K is Kelvin temperature, T represents the material temperature, with the unit K, t represents time, with the unit s, represents the vector differential operator, q represents the net heat flux density vector, with the unit W / m 2 , W is watt, Q represents the internal heat source, with the unit W / m 3 ;

[0107] where, represents the evaporation rate of water, with the unit kg / (m 3 *s), ΔH vap represents the latent heat of evaporation of water, with the unit J / kg;

[0108] where, k vap represents the evaporation rate constant, with the unit 1 / s, ρ L represents the liquid-phase density, with the unit kg / m 3 , p * represents the saturation vapor pressure, with the unit Pa, p G represents the pressure in the vacuum chamber, with the unit Pa; and,

[0109] p * = 10 A-B / (C+T) , where A, B, and C are constants, T represents the material temperature, in units of K.

[0110] The Fourier heat transfer law is used to construct the control equation for heat transfer inside the material. For complex heat transfer processes, such as heat transfer through multi-layer media and phase change heat transfer, etc., it can also be described and predicted. In addition, the Fourier law can accurately calculate the heat transfer rate by measuring a small number of parameters.

[0111] In one embodiment, the steps of constructing the control equation for heat transfer between the material and the environment through the heat transfer situation of the material boundary in the medium further include:

[0112] The Newton cooling law is used to construct the control equation for heat transfer between the material and the environment:

[0113] q = h(T ext - T), where q represents the net heat flux density vector on the material boundary, in units of W / m 2 , h represents the heat transfer coefficient on the boundary, in units of W / (m 2 *K), T ext represents the external environment temperature, in units of K, and T represents the material temperature, in units of K.

[0114] The Newton cooling law is used to construct the control equation for heat transfer between the material and the environment. By measuring a small number of parameters, it is easy to apply and can quickly calculate and predict the heat transfer rate between the material and the environment.

[0115] In one embodiment, the steps of constructing the mass transfer control equation of the material in the environment according to the law of mass transfer from the high-concentration region to the low-concentration region further include:

[0116] The Fick's second diffusion law is used to construct the mass transfer control equation of the material in the environment:

[0117] where θ L represents the volume fraction of the liquid phase, D L represents the apparent liquid diffusion coefficient, in units of m2 / s;

[0118] where α represents the proportionality constant, represents the residual saturation.

[0119] The mass transfer control equation of the material in the environment is constructed by using Fick's second law of diffusion. Fick's second law is derived on the basis of Fick's first law and combined with the mass conservation equation, which can accurately describe the transfer and accumulation of substances during the diffusion process. Fick's second law can more accurately describe the concentration change during the diffusion process, and this accuracy is very important for predicting and controlling the mass transfer process.

[0120] In one embodiment, the initial conditions set in step S5 include that the initial temperature T of the material is 353.15K and the moisture content θ L is 0.77g / g (the moisture content is usually the mass fraction, and here the moisture content is the volume fraction of the liquid phase). The boundary conditions include the environmental temperature T ext is 273.15K, the surface heat transfer coefficient h is 25W / (m2*K), and the evaporation rate m LG is 2.7*10-7kg / (m3*s).

[0121] As Figure 3 shown, in one embodiment, in step S5, the mesh division adopts a physical field control mesh, and the size is extremely refined. The number of meshes 21 is 11280. During actual operation, the model can be automatically meshed in Comsol. The meshes 21 are finer at the sharp corners and bends, and coarser at the flat places. Since the volume of the food material is small and the overall calculation amount is small after abstracting the geometry of the material into a two-dimensional axisymmetric model 1, the element size can be "extremely refined" and will not cause excessive calculation pressure. Actually, the size of the mesh division can be set according to the actual situation of the two-dimensional axisymmetric model 1 of the material.

[0122] In one embodiment, the steps of solving the control equation and post-processing the solution results further include:

[0123] Set the solver to transient;

[0124] Set the output time step according to the requirements of the preservation process;

[0125] Set up a plotting group to draw the data results according to the solution results of the control equation.

[0126] In one embodiment, when setting the output time step, if the total duration of a certain process is 90 minutes and the specific temperature and moisture content every 10 minutes need to be known, then set the time unit to min and the output time step to range(0,10,90). Through numerical simulation, the distribution of temperature and moisture at each position of the material at different times can be obtained. By setting up a plotting group to display the data results, as Figure 4 and Figure 5 shown. Collect the temperature data and moisture content data of the material during the vacuum cooling process to verify the numerical simulation results, as Figure 6 and Figure 7As shown, according to the simulation results and the comparison and verification with the simulation results, the same type of subsequent processes can all use this model for simulation and prediction, only by replacing the geometric model, materials, and process parameters, which can save time cost and resource cost.

[0127] It should be noted that the method for predicting the material state during the preservation process of the present invention can be applied not only to the vacuum cooling preservation process, but also to other preservation processes in non-vacuum environments.

[0128] As Figure 8 shown, the present invention also provides a device 10 for predicting the material state during the preservation process, which is used to implement the foregoing method, including:

[0129] A geometric model construction module 11, which establishes a geometric model of the material according to the shape of the material;

[0130] A material parameter module 12, which determines the material parameters of the geometric model according to the preservation process;

[0131] A physical field construction module 13, which constructs a physical field according to the geometric model and the material parameters. The physical field construction module 13 further includes:

[0132] A control equation construction module 14, which constructs a control equation for the physical field. Among them, a heat transfer control equation for the preservation process is constructed through the heat transfer inside the material and the heat transfer between the material and the medium, and a mass transfer control equation for the preservation process is constructed through the mass diffusion of the material in the environment;

[0133] A physical field setting module 15, which sets initial conditions, boundary conditions, and physical field parameters for the physical field;

[0134] A mesh generation module 16, which performs mesh generation on the geometric model;

[0135] A solution and post-processing module 17, which solves the control equation and post-processes the solution results.

[0136] In one embodiment, a physical field can be constructed, a control equation for the physical field can be constructed, and initial conditions, boundary conditions, and physical field parameters can be set for the physical field in the COMSOL simulation software. It should be noted that the simulation software used in the present invention is COMSOL, and other similar simulation software can also be used to implement the method of the present invention, which is not limited thereto.

[0137] As Figure 9 shown, the present invention also provides a vacuum cooling device 100, including:

[0138] A vacuum chamber 110, which is used to provide a vacuum environment for the material;

[0139] A vacuum unit 120, including a vacuum pump 121 and a vacuum valve 122 connected to the vacuum pump 121, the vacuum pump 121 and the vacuum valve 122 are used to provide a vacuum environment for the vacuum chamber 110;

[0140] A cooling unit 130, connected to the vacuum chamber 110, for providing cooling water;

[0141] A control unit 140, connected to the vacuum pump 121 and the cooling unit 140,

[0142] The aforementioned device 10 for predicting the state of materials during the preservation process, the device 10 for predicting the state of materials during the preservation process is connected to the control unit 140.

[0143] The present invention also provides a storage medium for storing a computer control program, and the computer control program is used to execute the steps of any one of the foregoing methods.

[0144] It should be understood that the storage medium in the embodiments of the present invention may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of random access memory (RAM) are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus random access memory (DR RAM).

[0145] A method, device and vacuum cooling device for predicting the state of materials during preservation according to the present invention construct a geometric model of the materials and material parameters of the geometric model, construct a physical field based on the geometric model and the material parameters, and construct a control equation for the physical field. Among them, a heat transfer control equation for the preservation process is constructed through heat transfer inside the materials and heat transfer between the materials and the medium, and a mass transfer control equation during the preservation process is constructed through the mass diffusion of the materials in the environment. The control equation is solved to obtain the simulation result of the state of the materials during the preservation process. According to this simulation result, the preservation process can be precisely controlled to better maintain the quality of the materials.

[0146] In summary, the present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can evolve various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the patent applied for by the present invention.

Claims

1. A method for predicting the state of materials during the preservation process, characterized in that, Including the following steps: Establish a geometric model of the material according to the shape of the material; Determine the material parameters of the geometric model according to the preservation process; Construct a physical field according to the geometric model and the material parameters; Construct a control equation for the physical field, wherein a heat transfer control equation for the preservation process is constructed through heat transfer inside the material and heat transfer between the material and the medium, and a mass transfer control equation in the preservation process is constructed through the mass diffusion of the material in the environment; Set initial conditions, boundary conditions, and physical field parameters for the physical field; Perform mesh division on the geometric model; Solve the control equation and post-process the solution results.

2. The method according to claim 1, wherein The step of constructing the heat transfer control equation for the preservation process through heat transfer inside the material and heat transfer between the material and the medium further includes: Construct a heat transfer control equation inside the material according to the law of conservation of energy of heat transfer in the medium; Construct a heat transfer control equation between the material and the environment through the heat transfer situation of the boundary of the material in the medium.

3. The method according to claim 1, wherein The step of constructing the mass transfer control equation in the preservation process through the mass diffusion of the material in the environment further includes: Construct a mass transfer control equation of the material in the environment according to the law of transfer of substances from a high-concentration region to a low-concentration region.

4. The method according to claim 2, wherein The step of constructing a heat transfer control equation inside the material according to the law of conservation of energy of heat transfer in the medium further includes: Construct a heat transfer control equation inside the material using Fourier's law of heat conduction: Among them, ρ represents density, with the unit kg / m 3 , C P represents the constant-pressure heat capacity, with the unit J / (kg / K), where J is joule and K is the Kelvin temperature, T represents the material temperature, with the unit K, t represents time, with the unit s, represents the vector differential operator, q represents the net heat flux density vector, with the unit W / m 2 , W is watt, Q represents the internal heat source, W / m 3 ; Among them, represents the evaporation rate of moisture, with the unit of kg / (m 3 *s), and ΔH vap represents the latent heat of evaporation of moisture, with the unit of J / kg; Among them, k vap represents the evaporation rate constant, with the unit of 1 / s, ρ L represents the liquid-phase density, with the unit of kg / m 3 , p * represents the saturated vapor pressure, with the unit of Pa, p G represents the pressure in the vacuum chamber, with the unit of Pa; and, p * = 10 A-B / (C+T) , where A, B, and C are constants, T represents the material temperature, in units of K.

5. The method according to claim 2, characterized in that, The step of constructing a heat transfer control equation between the material and the environment through the heat transfer situation of the boundary of the material in the medium further includes: Construct a heat transfer control equation between the material and the environment using Newton's law of cooling: q = h(T ext - T), where q represents the net heat flux density vector on the material boundary, with the unit of W / m 2 , h represents the heat transfer coefficient on the boundary, with the unit of W / (m 2 *K), T ext represents the external environment temperature, with the unit of K, and T represents the material temperature, with the unit of K.

6. The method according to claim 3, wherein The step of constructing a mass transfer control equation of the material in the environment according to the law of transfer of substances from a high-concentration region to a low-concentration region further includes: Construct a mass transfer control equation of the material in the environment using Fick's second law of diffusion: Among them, θ L represents the volume fraction of the liquid phase, and D L represents the apparent liquid diffusion coefficient, with the unit of m2 / s; where α represents a proportionality constant, represents the residual saturation.

7. The method according to claim 1, wherein The step of solving the control equation and post-processing the solution results further includes: Set the solver to transient; Set the output time step according to the requirements of the preservation process; Set a plot group to draw data results according to the solution results of the control equation.

8. An apparatus for predicting the state of materials during the preservation process, which is used to implement the method according to any one of claims 1 to 7, characterized in that, Including: A geometric model construction module that establishes a geometric model of the material according to the shape of the material; A material parameter module that determines the material parameters of the geometric model according to the preservation process; A physical field construction module that constructs a physical field according to the geometric model and the material parameters. The physical field construction module further includes: A control equation construction module that constructs a control equation for the physical field, wherein a heat transfer control equation for the preservation process is constructed through heat transfer inside the material and heat transfer between the material and the medium, and a mass transfer control equation in the preservation process is constructed through the mass diffusion of the material in the environment; A physical field setting module that sets initial conditions, boundary conditions, and physical field parameters for the physical field; A mesh division module that performs mesh division on the geometric model; A solution and post-processing module that solves the control equation and post-processes the solution results.

9. A vacuum cooling device, characterized in that, Including: A vacuum chamber for providing a vacuum environment for the material; A vacuum unit, comprising a vacuum pump and a vacuum valve connected to the vacuum pump, wherein the vacuum pump and the vacuum valve are used to provide a vacuum environment for the vacuum chamber; A cooling unit, connected to the vacuum chamber, for providing cooling water; A control unit, connected to the vacuum pump and the cooling unit; The device for predicting the state of materials during the preservation process as claimed in claim 8, wherein the device for predicting the state of materials during the preservation process is connected to the control unit.

10. A storage medium for storing a computer control program, characterized in that, The computer control program is used to execute the steps of the method as claimed in any one of claims 1 to 7.

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