A method for obtaining a moisture diffusion coefficient

Abstract

This invention belongs to the field of humidity control technology and discloses a method for obtaining the moisture diffusion coefficient. Based on a sealed cavity with a vent valve, the sealed cavity has multiple measurement points. The method includes the following steps: obtaining the diffusion distance from each measurement point to the vent valve; obtaining the temperature and humidity of the external environment of the sealed cavity within a preset time period; obtaining the temperature and humidity of each measurement point inside the sealed cavity within the preset time period; and calculating the moisture diffusion coefficient using the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measurement point. This method can obtain the moisture diffusion coefficient under various conditions, thus providing reference data for condensation simulation calculations in equipment cavities.

Description

Technical Field

[0001] This invention relates to the field of humidity control technology, and in particular to a method for obtaining the moisture diffusion coefficient. Background Technology

[0002] Many applications now require equipment cavities with vent valves (such as base stations, motors, electrical controls, vehicle lights, batteries, power cabinets, and lidar systems). The insulation capacity of these cavities is a crucial factor in their safe and stable operation. Besides inherent design, materials, and quality factors, the insulation capacity of these cavities is frequently compromised by harsh environmental conditions such as temperature, humidity, and condensation. Long-term operational experience with some power cabinets shows that condensation inside the cabinet leads to a decline in internal insulation performance, and various insulation defects can gradually develop into breakdowns, causing accidents and significantly impacting the stability of the entire power system. Therefore, addressing condensation in switchgear is vital for the safe operation of switchgear and the stability of the power grid.

[0003] Currently, the understanding of condensation phenomena in switchgear is not in-depth. The physical process of condensation, especially the energy and mass exchange mechanism in condensation, is not clear. There is also a lack of systematic analysis of the factors affecting condensation under different operating conditions. It is urgent to conduct in-depth research on its condensation process and influencing factors. Summary of the Invention

[0004] In view of the above-mentioned shortcomings, the present invention provides a method for obtaining the moisture diffusion coefficient, which can obtain the moisture diffusion coefficient under various conditions, thereby providing reference data for the simulation calculation of condensation in equipment cavities.

[0005] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0006] A method for obtaining the moisture diffusion coefficient, based on a sealed cavity with a vent valve, wherein multiple measurement points are provided within the sealed cavity, the method comprising the following steps:

[0007] Obtain the diffusion distance from each measurement point to the vent valve;

[0008] Obtain the temperature and humidity of the external environment of the sealed cavity within a preset time period;

[0009] Obtain the temperature and humidity at various measurement points inside the sealed cavity within a preset time period;

[0010] The moisture diffusion coefficient is calculated using the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity at each measurement point.

[0011] According to one aspect of the present invention, obtaining the diffusion distance from each measurement point to the vent valve includes: establishing a three-dimensional coordinate system, obtaining the coordinate points of the vent valve and each measurement point, and calculating the straight-line distance from the coordinate points of the measurement points to the coordinate points of the vent valve as the diffusion distance from the measurement points to the vent valve.

[0012] According to one aspect of the present invention, the step of calculating the moisture diffusion coefficient by means of the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measuring point includes: combining different external environmental temperatures and humidity to calculate the moisture diffusion coefficient by means of the half-life method.

[0013] According to one aspect of the present invention, the step of calculating the moisture diffusion coefficient by means of the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measurement point includes: setting the external environment temperature to be the same, obtaining the moisture diffusion coefficient under different external environment humidity, calculating the humidity influence function, and thus fitting the moisture diffusion coefficient.

[0014] According to one aspect of the present invention, the step of calculating the moisture diffusion coefficient by means of the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measurement point includes: setting the external environment humidity to be the same, obtaining the moisture diffusion coefficient at different external environment temperatures, calculating the temperature influence function, and thus fitting the moisture diffusion coefficient.

[0015] According to one aspect of the present invention, the method includes: obtaining the internal surface temperature of a sealed cavity and determining the degree of condensation based on the humidity diffusion coefficient at the current location.

[0016] According to one aspect of the present invention, the method includes the following steps: obtaining the moisture diffusion coefficient under different temperature and humidity conditions, and fitting the influence function of temperature and humidity on the moisture diffusion coefficient.

[0017] According to one aspect of the present invention, the method includes the following steps: setting a humidity-regulating material at a measurement point, and obtaining a moisture diffusion coefficient when the humidity-regulating material is present at the measurement point.

[0018] According to one aspect of the present invention, the method includes the following steps: obtaining the moisture diffusion coefficient at different locations and under different humidity-regulating materials, thereby fitting a function of the influence of the humidity-regulating material on the moisture diffusion coefficient.

[0019] According to one aspect of the invention, the method includes the following step: the humidity-regulating material placed at each location has the same weight.

[0020] The advantages of this invention are as follows: First, by fitting experimental data from multiple locations and with multiple material conditions, an influence function model is established, which can quantitatively characterize the dynamic influence of different humidity-regulating materials on moisture transfer within the cavity. Second, by standardizing the configuration of humidity-regulating materials at measurement points, measurement deviations caused by uneven material distribution are effectively eliminated, improving the accuracy of moisture diffusion coefficient measurements. Third, adopting a uniform weight configuration principle not only simplifies the experimental operation process but also ensures the comparability of data between different measurement points, providing a reliable parameter basis for establishing a three-dimensional humidity field simulation. Finally, a reusable optimized configuration scheme for humidity-regulating materials is formed, providing precise theoretical support for humidity control engineering in fields such as electrical cabinets and electrical equipment. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a method for obtaining the moisture diffusion coefficient according to the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] like Figure 1 As shown, a method for obtaining the moisture diffusion coefficient is based on a sealed cavity with a vent valve, wherein multiple measurement points are provided within the sealed cavity. The method includes the following steps:

[0026] Step S1: Obtain the diffusion distance from each measurement point to the vent valve;

[0027] First, the positions and diffusion distances of multiple measurement points within the sealed cavity are obtained. A three-dimensional coordinate system is established, and the coordinates of the vent valve and each measurement point are acquired. The reference position is set based on the geometric center of the vent valve or the valve port reference point. The coordinates of the measurement point are set as (x, y, z). The straight-line distance from the measurement point to the air valve is calculated as the diffusion distance L from the measurement point to the air valve. The coordinates of the i-th measurement point are (x, y, z). i， yi， z i Define its equivalent diffusion distance:

[0028]

[0029] Because the sensor cannot be installed at the ideal point on the valve port, i.e. At this location, all actual measurement points meet the requirements. .

[0030] Step S2: Obtain the temperature and humidity of the external environment of the sealed cavity within a preset time period;

[0031] Temperature and humidity sensors and surface temperature sensors are deployed outside the sealed cavity of the equipment to acquire temperature and humidity data of the external environment. The acquired external environmental temperature and humidity can be actual temperature and humidity obtained through measurement, or it can be set as needed based on predefined conditions. The preset time is t.

[0032] In this embodiment, various combinations of external environmental temperature and humidity are set according to the actual working scenario, working state, and start / stop state of the equipment to form different external temperature and humidity conditions. For example: Group 1: T out =15℃,RH out =30%; Group 2: T out =25℃,RH out =60%; Group 3: T out =35℃,RH out =90%; Group 4: T out =50℃,RH out =50%, etc.; where T out Represents the external ambient temperature, RH out This represents the humidity of the external environment.

[0033] Step S3: Obtain the temperature and humidity at each measurement point inside the sealed cavity within a preset time period;

[0034] Temperature and humidity sensors and surface temperature sensors are deployed at different locations inside the sealed cavity of the equipment, such as the vent valve and measurement points. The temperature and humidity data of the vent valve and multiple measurement points inside the equipment are obtained through the deployed temperature and humidity sensors and surface temperature sensors.

[0035] Step S4: Based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measurement point, the moisture diffusion coefficient is calculated using the half-life method.

[0036] The step described above calculates the moisture diffusion coefficient using the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity at each measurement point.

[0037] Step S41: Starting from the error function solution of one-dimensional diffusion, by setting the half-life condition... Relationship obtained:

[0038] ;

[0039] Here, w(x,t) is defined as the moisture state quantity inside the cavity, typically chosen as absolute humidity (AH), with units of g / m³. 3 When the temperature field is approximately uniform, the water vapor partial pressure p can also be used as an equivalent method. v , i.e., the equivalent quantity monotonically corresponding to water vapor concentration; x: one-dimensional equivalent diffusion coordinate, x=0 is the permeable boundary, x>0 is the interior of the cavity; w0 is the initial humidity value, i.e., the initial moisture state quantity inside at t=0; w ext Where D is the humidity balance value, and D is the moisture diffusion coefficient, also known as the equivalent moisture diffusion coefficient (m). 2 / s), which are the constant parameters to be identified for "single test / single equivalent path", where L is the equivalent diffusion distance (m) from the measurement point to the permeable boundary; t 1 / 2 The half-life is given by k = erfc. - ¹(1 / 2) is approximately 0.4769, thus yielding:

[0040] ;

[0041] Thus, the moisture diffusion coefficient D at each measurement point is obtained. L D L Let be the equivalent diffusion coefficient corresponding to the measuring point at a distance of L; let D0 at the vent valve be used as the reference moisture diffusion coefficient. D0 is the reference diffusion coefficient, which is the equivalent diffusion capacity parameter (not the value substituted when L=0) corresponding to the reference area near the vent valve under reference temperature and humidity (T0, RH0) and no humidity-regulating material conditions.

[0042] The modeling of the diffusion coefficient is based on:

[0043] (1) Single solution layer: In a specific experiment (temperature T, external humidity program, equipment structure and state are fixed) and an equivalent diffusion path, the equivalent diffusion coefficient D is regarded as a constant parameter, and the constant coefficient diffusion equation is used to solve and obtain the analytical solution of the error function.

[0044] (2) Parameter identification layer: obtained by combining the analytical solution with the half-life condition. This belongs to the "parameter inversion / identification formula", which means "given the L of this experiment and the measured t". 1 / 2The constant parameter D corresponding to this experiment can be obtained by reverse calculation. This relationship does not mean that D can be written as D(L) or D(x) in the same partial differential equation.

[0045] (3) Cross-test fitting layer: When the measuring point is changed (different L) or the operating conditions are changed (different T, RH), the equivalent diffusion coefficient data points (such as DL, D(T,RH)) under different test objects are obtained, which are used to regress and fit the temperature and humidity influence function. This does not contradict the principle of "taking D as a constant in a single solution".

[0046] In this embodiment, step S41 involves solving the error function to... The entire derivation process is as follows:

[0047] 41.1 Governing equations and constant coefficient reduction;

[0048] The one-dimensional general form of Fick's second law is:

[0049] (Equation 1) ;

[0050] If D is approximated as a constant in a single trial and along a single equivalent path, then it becomes:

[0051] (Equation 2) ;

[0052] 41.2 Initial and Boundary Conditions (Semi-Infinite One-Dimensional Model);

[0053] Let x be the one-dimensional equivalent diffusion coordinate, x=0 be the air-permeable boundary, and x>0 be the interior of the cavity. Take:

[0054] (Equation 3) Initial conditions: w(x,0)=w0, x>0.

[0055] w0: Initial moisture state quantity inside the unit at time t=0.

[0056] (Equation 4) Boundary condition: w(0,t)=w ext , t>0 (approximately constant within the identification window).

[0057] 41.3 Analytical solution of the error function;

[0058] The standard analytical solution to the above classical semi-infinite diffusion problem is:

[0059] (Equation 5) ;

[0060] Equivalently, it can also be written in the form of a complementary error function:

[0061] (Equation 6) .

[0062] 41.4 Substituting the half-life condition into the inversion of D;

[0063] Define the half-life t at the measurement point x=L. 1 / 2 :

[0064] (Equation 7) ;

[0065] Substituting equation 5 into equation 7, we get:

[0066] (Equation 8) ;

[0067] make ;

[0068] but:

[0069] (Equation 9) ;

[0070] Summarized as follows:

[0071] (Equation 10) .

[0072] Step S42: Due to the influence of humidity and temperature in various scenarios, the diffusion coefficient will be different. Therefore, it needs to be calculated using the following formula:

[0073] ;

[0074] The above equation is the moisture diffusion equation, where AH(x,y,z,t) is the absolute humidity at position (x,y,z) and time t, with units of g / m³. 3 The calculation method is as follows:

[0075] ;

[0076] divergence term This describes the net effect of moisture flow or diffusion, i.e., the net amount of moisture flowing into or out of a volume element. This term reflects the process of moisture diffusing from a region of high concentration to a region of low concentration in space.

[0077] D(T,RH) is the diffusion coefficient under the influence of temperature and humidity. It depends on the temperature T and relative humidity RH and changes dynamically over time. The diffusion coefficient reflects the rate of moisture diffusion: the larger the diffusion coefficient, the faster the moisture diffuses.

[0078] This is the spatial gradient of moisture concentration, which describes how moisture concentration changes in space. The direction of the gradient points in the direction of the fastest increase in moisture concentration, while the magnitude represents the rate of change of moisture concentration per unit distance in that direction.

[0079] This is the spatial gradient of moisture diffusion, representing the change and diffusion process of moisture concentration in space. Specifically, the change in moisture concentration is related not only to the spatial diffusion rate but also closely related to the temporal change. According to the diffusion equation, the temporal change of moisture is reflected through spatial diffusion.

[0080] The moisture diffusion coefficient at each point can be obtained using the moisture diffusion equation. The calculation method is as follows:

[0081] ;

[0082] D0 is the baseline moisture diffusion coefficient, with the reference point selected at the location of the vent valve. It represents the diffusion coefficient without any moisture-regulating material, and is expressed in meters (m). 2 / s, obtained through step S41; D0 is used to characterize the baseline equivalent moisture exchange capacity between the cavity and the outside world under baseline temperature and humidity conditions. D0 is not obtained by substituting L=0 into the formula. The reason is that the boundary condition w(0,t)=w is satisfied at x=0. ext There is no flow from w0 to w at this location. ext The diffusion response curve shows that the half-life condition degenerates at x=0 (t). 1 / 2 →0), therefore D0 must be obtained from measurable points where L>0.

[0083] D0 can be obtained using the following methods:

[0084] Method A: Definition of nearest measurement point;

[0085] Under baseline conditions (T0, RH0) and without conditioning material, select a set of measuring points close to the vent valve, and take the minimum distance L among them. min For measuring points >0, calculate according to formula 10. and define:

[0086] (Equation 12) D0 = ;

[0087] Alternatively, several measuring points closest to the valve orifice can be selected, and their D values ​​can be measured. L Use the average / weighted average as D0 to improve repeatability.

[0088] Method B: Multi-point regression identification method (avoiding the misinterpretation of "D follows L", directly identifying from the "proportional relationship between half-life and squared distance")

[0089] Under the same reference conditions, select a set S of multiple measuring points close to the valve orifice. From Equation 10, an approximate proportional relationship can be obtained:

[0090] (Equation 13) , ( .

[0091] by For dependent variable, Performing least squares regression on the independent variable, we obtain the slope 'a', then:

[0092] (Equation 14) .

[0093] It is a function of the effect of temperature on the diffusion coefficient;

[0094] It is a function of the effect of humidity on the diffusion coefficient.

[0095] in, α is the effect coefficient of temperature on the diffusion coefficient, and T0 is the reference temperature (e.g., 25°C). ; γ is the influence coefficient of humidity on the diffusion coefficient, and RH0 is the reference humidity (e.g., 60%). .

[0096] The influence coefficients α and γ of temperature and humidity on the diffusion coefficient were obtained by fitting the measured AH gradient and the corresponding D (derived through deduction).

[0097] In other words, the influence coefficients mentioned above are obtained by using regression analysis to fit the effects of temperature and humidity on the diffusion coefficient through the data from the first stage.

[0098] ;

[0099] By following the steps above, the moisture diffusion coefficient of a sealed cavity with a breathable valve under the influence of temperature and humidity can be obtained, thus providing a basis for the temperature and humidity control of the equipment.

[0100] In this embodiment, the specific method for calculating the moisture diffusion coefficient is obtained through the following experimental process:

[0101] Phase 1:

[0102] 1.1 Objective: To obtain the diffusion coefficient under conditions without humidity control materials and to fit the influence functions of temperature f(T) and humidity f(RH).

[0103] 1.2 Experimental conditions:

[0104] Equipment: Select equipment chambers with vent valves (such as base stations, motors, electrical control systems, power cabinets, etc.) to ensure that there are multiple measurement points inside.

[0105] External temperature and humidity: Set different combinations of external temperature and humidity to ensure different environmental conditions when the equipment is in working, dormant, or start-stop states.

[0106] Internal temperature and humidity: Temperature and humidity sensors are deployed in different locations inside the equipment to record the air humidity and temperature at each location.

[0107] Equipment surface temperature: Thermocouples are placed at different locations on the inner surface of the equipment, with a focus on the low-temperature region.

[0108] Equipment operating state, hibernation state, and start-stop state: Simulates the actual working conditions of the equipment, including changes in temperature and humidity during the start-up and shutdown process.

[0109] 1.3 Experimental Procedure:

[0110] Equipment preparation: Ensure that there are no humidity-regulating materials inside the equipment (consistent with the actual application scenario), and install temperature and humidity sensors and thermocouples in several key locations.

[0111] External environment control: Set and adjust the external temperature and humidity, record the external and internal temperature and humidity data of the equipment, and set the equipment's working state and start / stop state.

[0112] Temperature and humidity data recording: Record the humidity and temperature data of the air inside the equipment and the temperature of the inner surface of the equipment at different locations to ensure the time synchronization of the data.

[0113] Calculation of diffusion coefficient: The baseline moisture diffusion coefficient D0 was calculated using the half-life method, and the influence functions of temperature f(T) and humidity f(RH) were fitted using experimental data.

[0114] 1.4 Experimental Parameters and Measurement Methods:

[0115] Internal temperature and humidity of the equipment: Temperature and humidity sensors and thermocouples are placed in multiple key locations to ensure the acquisition of humidity and temperature data of the air inside the equipment, as well as the temperature of the internal surfaces of the equipment.

[0116] External ambient temperature and humidity: The environmental control system is used to adjust and record the external temperature and humidity in real time.

[0117] Humidity change rate: Calculate the half-life of humidity change at each location and calculate the diffusion coefficient D.

[0118] Data synchronization: Use a data acquisition system to synchronously record data from each sensor.

[0119] Fitting :

[0120] Objective: To fit the influence function of temperature and humidity on the diffusion coefficient using the data from the first stage.

[0121] Methods: Regression analysis was used to fit the effects of temperature and humidity on the diffusion coefficient.

[0122] This method has a sound theoretical basis and correct dimensions, and can utilize the half-life t. 1 / 2 The diffusion coefficient was inverted, and the respective influencing parameters were further fitted by combining temperature and humidity data, thereby providing a quantitative basis for the subsequent design of internal humidity dynamics and anti-condensation of equipment.

[0123] This embodiment successfully established a quantitative influence model of temperature and humidity on the diffusion coefficient by combining multi-sensor collaborative monitoring with regression analysis. This approach not only achieves non-destructive in-situ measurement but also effectively reflects the transient characteristics of the moisture diffusion process by introducing a dynamic parameter of half-life. The model is based on the principle of dimensional consistency. The two-factor equation allows for the mathematical separation of temperature and humidity effects, ensuring both the clarity of the physical meaning and significantly improving the accuracy of parameter identification. Simultaneously, its standardized data processing workflow ensures the engineering reproducibility of the experimental results.

[0124] Example 2

[0125] like Figure 1 As shown, a method for obtaining the moisture diffusion coefficient is based on a sealed cavity with a vent valve, wherein multiple measurement points are provided within the sealed cavity. The method includes the following steps:

[0126] Step S1: Obtain the diffusion distance from each measurement point to the vent valve;

[0127] First, the positions and diffusion distances of multiple measurement points within the sealed cavity are obtained. A three-dimensional coordinate system is established, and the coordinates of the vent valve and each measurement point are acquired. The reference position is set based on the geometric center of the vent valve or the valve port reference point. The coordinates of the measurement point are set as (x, y, z). The straight-line distance from the measurement point to the air valve is calculated as the diffusion distance L from the measurement point to the air valve. The coordinates of the i-th measurement point are (x, y, z). i， y i， z i Define its equivalent diffusion distance:

[0128]

[0129] Because the sensor cannot be installed at the ideal point on the valve port, i.e. At this location, all actual measurement points meet the requirements. .

[0130] During this process, humidity-regulating materials are placed at each measuring point, and the mass W of the humidity-regulating materials at each measuring point is the same. The position of the humidity-regulating materials is measured using an electronic scale. .

[0131] Step S2: Obtain the temperature and humidity of the external environment of the sealed cavity within a preset time period;

[0132] Temperature and humidity sensors and surface temperature sensors are deployed outside the sealed cavity of the equipment to acquire temperature and humidity data of the external environment. The acquired external environmental temperature and humidity can be actual temperature and humidity obtained through measurement, or it can be set as needed based on predefined conditions. The preset time is t.

[0133] In this embodiment, various combinations of external environmental temperature and humidity are set according to the actual working scenario, working state, and start / stop state of the equipment to form different external temperature and humidity conditions. For example: Group 1: T out =15℃,RH out =30%; Group 2: T out =25℃,RH out =60%; Group 3: T out =35℃,RH out =90%; Group 4: T out =50℃,RH out =50%, etc.; where T out Represents the external ambient temperature, RH out This represents the humidity of the external environment.

[0134] Step S3: Obtain the temperature and humidity at each measurement point inside the sealed cavity within a preset time period;

[0135] Temperature and humidity sensors and surface temperature sensors are deployed at different locations inside the sealed cavity of the equipment, such as the vent valve and measurement points. The temperature and humidity data of the vent valve and multiple measurement points inside the equipment are obtained through the deployed temperature and humidity sensors and surface temperature sensors.

[0136] Step S4: Based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measurement point, the moisture diffusion coefficient is calculated using the half-life method.

[0137] The step described above calculates the moisture diffusion coefficient using the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity at each measurement point.

[0138] Step S41: Starting from the error function solution of one-dimensional diffusion, by setting the half-life condition... Relationship obtained:

[0139] ;

[0140] Here, w(x,t) is defined as the moisture state quantity inside the cavity, typically chosen as absolute humidity (AH), with units of g / m³. 3 When the temperature field is approximately uniform, the water vapor partial pressure p can also be used as an equivalent method.v , i.e., the equivalent quantity monotonically corresponding to water vapor concentration; x: one-dimensional equivalent diffusion coordinate, x=0 is the permeable boundary, x>0 is the interior of the cavity; w0 is the initial humidity value, i.e., the initial moisture state quantity inside at t=0; w ext Where D is the humidity balance value, and D is the moisture diffusion coefficient, also known as the equivalent moisture diffusion coefficient (m). 2 / s), which are the constant parameters to be identified for "single test / single equivalent path", where L is the equivalent diffusion distance (m) from the measurement point to the permeable boundary; t 1 / 2 The half-life is given by k = erfc. - ¹(1 / 2) is approximately 0.4769, thus yielding:

[0141] ;

[0142] Thus, the moisture diffusion coefficient D at each measurement point is obtained. L D L Let be the equivalent diffusion coefficient corresponding to the measuring point at a distance of L; let D0 at the vent valve be used as the reference moisture diffusion coefficient. D0 is the reference diffusion coefficient, which is the equivalent diffusion capacity parameter (not the value substituted when L=0) corresponding to the reference area near the vent valve under reference temperature and humidity (T0, RH0) and no humidity-regulating material conditions.

[0143] The modeling of the diffusion coefficient is based on:

[0144] (1) Single solution layer: In a specific experiment (temperature T, external humidity program, equipment structure and state are fixed) and an equivalent diffusion path, the equivalent diffusion coefficient D is regarded as a constant parameter, and the constant coefficient diffusion equation is used to solve and obtain the analytical solution of the error function.

[0145] (2) Parameter identification layer: obtained by combining the analytical solution with the half-life condition. This belongs to the "parameter inversion / identification formula", which means "given the L of this experiment and the measured t". 1 / 2 The constant parameter D corresponding to this experiment can be obtained by reverse calculation. This relationship does not mean that D can be written as D(L) or D(x) in the same partial differential equation.

[0146] (3) Cross-test fitting layer: When the measuring point is changed (different L) or the operating conditions are changed (different T, RH), the equivalent diffusion coefficient data points (such as DL, D(T,RH)) under different test objects are obtained, which are used to regress and fit the temperature and humidity influence function. This does not contradict the principle of "taking D as a constant in a single solution".

[0147] In this embodiment, step S41 involves solving the error function to... The entire derivation process is as follows:

[0148] 41.1 Governing equations and constant coefficient reduction;

[0149] The one-dimensional general form of Fick's second law is:

[0150] (Equation 1) ;

[0151] If D is approximated as a constant in a single trial and along a single equivalent path, then it becomes:

[0152] (Equation 2) ;

[0153] 41.2 Initial and Boundary Conditions (Semi-Infinite One-Dimensional Model);

[0154] Let x be the one-dimensional equivalent diffusion coordinate, x=0 be the air-permeable boundary, and x>0 be the interior of the cavity. Take:

[0155] (Equation 3) Initial conditions: w(x,0)=w0, x>0.

[0156] w0: Initial moisture state quantity inside the unit at time t=0.

[0157] (Equation 4) Boundary condition: w(0,t)=w ext , t>0 (approximately constant within the identification window).

[0158] 41.3 Analytical solution of the error function;

[0159] The standard analytical solution to the above classical semi-infinite diffusion problem is:

[0160] (Equation 5) ;

[0161] Equivalently, it can also be written in the form of a complementary error function:

[0162] (Equation 6) .

[0163] 41.4 Substituting the half-life condition into the inversion of D;

[0164] Define the half-life t at the measurement point x=L. 1 / 2 :

[0165] (Equation 7) ;

[0166] Substituting equation 5 into equation 7, we get:

[0167] (Equation 8) ;

[0168] make ;

[0169] but:

[0170] (Equation 9) ;

[0171] Summarized as follows:

[0172] (Equation 10) .

[0173] Step S42: Due to the influence of humidity and temperature in various scenarios, the diffusion coefficient will be different. Therefore, it needs to be calculated using the following formula:

[0174] ;

[0175] The moisture diffusion equation, AH(x,y,z,t), represents the absolute humidity at location (x,y,z) and time t, with units of g / m³. 3 ;

[0176] divergence term This describes the net effect of moisture flow or diffusion, i.e., the net amount of moisture flowing into or out of a volume element. This term reflects the process of moisture diffusing from a region of high concentration to a region of low concentration in space.

[0177] D(W,T,RH) is the diffusion coefficient under the influence of humidity-regulating materials. It depends on the weight W of the humidity-regulating materials, the temperature T, and the relative humidity RH, and changes dynamically over time. The diffusion coefficient reflects the rate of moisture diffusion: the larger the diffusion coefficient, the faster the moisture diffuses.

[0178] This is the spatial gradient of moisture concentration, which describes how moisture concentration changes in space. The direction of the gradient points in the direction of the fastest increase in moisture concentration, while the magnitude represents the rate of change of moisture concentration per unit distance in that direction.

[0179] This is the spatial gradient of moisture diffusion, representing the change and diffusion process of moisture concentration in space. Specifically, the change in moisture concentration is related not only to the spatial diffusion rate but also closely related to the temporal change. According to the diffusion equation, the temporal change of moisture is reflected through spatial diffusion.

[0180] The moisture diffusion coefficient at each point can be obtained using the moisture diffusion equation. The calculation method is as follows:

[0181] ;

[0182] D0 is the baseline moisture diffusion coefficient, with the reference point selected at the location of the vent valve. It represents the diffusion coefficient without any moisture-regulating material, and is expressed in meters (m). 2 / s, obtained through step S41; D0 is used to characterize the baseline equivalent moisture exchange capacity between the cavity and the outside world under baseline temperature and humidity conditions. D0 is not obtained by substituting L=0 into the formula. The reason is that the boundary condition w(0,t)=w is satisfied at x=0. ext There is no flow from w0 to w at this location. ext The diffusion response curve shows that the half-life condition degenerates at x=0 (t). 1 / 2 →0), therefore D0 must be obtained from measurable points where L>0.

[0183] D0 can be obtained using the following methods:

[0184] Method A: Definition of nearest measurement point;

[0185] Under baseline conditions (T0, RH0) and without conditioning material, select a set of measuring points close to the vent valve, and take the minimum distance L among them. min For measuring points >0, calculate according to formula 10. and define:

[0186] (Equation 12) D0 = ;

[0187] Alternatively, several measuring points closest to the valve orifice can be selected, and their D values ​​can be measured. L Use the average / weighted average as D0 to improve repeatability.

[0188] Method B: Multi-point regression identification method (avoiding the misinterpretation of "D follows L", directly identifying from the "proportional relationship between half-life and squared distance")

[0189] Under the same reference conditions, select a set S of multiple measuring points close to the valve orifice. From Equation 10, an approximate proportional relationship can be obtained:

[0190] (Equation 13) , ( .

[0191] by For dependent variable, Performing least squares regression on the independent variable, we obtain the slope 'a', then:

[0192] (Equation 14) .

[0193] It is a function of the effect of temperature on the diffusion coefficient;

[0194] It is a function of the effect of humidity on the diffusion coefficient;

[0195] It is a function of the effect of humidity conditioning material on the diffusion coefficient, which depends on the weight of the humidity conditioning material and its moisture absorption / release characteristics.

[0196] in, α is the effect coefficient of temperature on the diffusion coefficient, and T0 is the reference temperature (e.g., 25°C). ; γ is the influence coefficient of humidity on the diffusion coefficient, and RH0 is the reference humidity (e.g., 60%). ; β is a constant representing the effectiveness factor of the humidity-regulating material, which determines the material's ability to inhibit moisture diffusion. The larger the β value, the more significant the influence of the humidity-regulating material on moisture diffusion. The influence coefficients α and γ of temperature and humidity on the diffusion coefficient are obtained by fitting the measured AH gradient with the corresponding D (derived through deduction).

[0197] ;

[0198] To ultimately obtain the influence function of the humidity-regulating material on the diffusion coefficient, a multi-stage experiment can be designed. In the first stage, inside a device without the humidity-regulating material, multiple test points are deployed (measuring air temperature and humidity at different locations, as well as the device surface temperature at different locations). Then, in both the device's operating and start-stop states, different external temperature and humidity data are combined to obtain real-time data and obtain the fitted value. The function is given. In the second stage, under the same conditions as in the first stage, the same mass of humidity-regulating material is placed at a different location each time, and the diffusion coefficient D is calculated using experimental data. This allows us to obtain the difference in diffusion coefficient at different locations under the same external temperature and humidity combination, with and without the humidity-regulating material, in both the operating and start-up / shutdown states of the equipment. Through the above experimental design, we finally obtain... .

[0199] In this embodiment, the specific method for calculating the moisture diffusion coefficient is obtained through the following experimental process:

[0200] Phase 1:

[0201] 1.1 Objective: To obtain the diffusion coefficient under conditions without humidity control materials and to fit the influence functions of temperature f(T) and humidity f(RH).

[0202] 1.2 Experimental conditions:

[0203] Equipment: Select equipment chambers with vent valves (such as base stations, motors, electrical control systems, power cabinets, etc.) to ensure that there are multiple measurement points inside.

[0204] External temperature and humidity: Set different combinations of external temperature and humidity to ensure different environmental conditions when the equipment is in working, dormant, or start-stop states.

[0205] Internal temperature and humidity: Temperature and humidity sensors are deployed in different locations inside the equipment to record the air humidity and temperature at each location.

[0206] Equipment surface temperature: Thermocouples are placed at different locations on the inner surface of the equipment, with a focus on the low-temperature region.

[0207] Equipment operating state, hibernation state, and start-stop state: Simulates the actual working conditions of the equipment, including changes in temperature and humidity during the start-up and shutdown process.

[0208] 1.3 Experimental Procedure:

[0209] Equipment preparation: Ensure that there are no humidity-regulating materials inside the equipment (consistent with the actual application scenario), and install temperature and humidity sensors and thermocouples in several key locations.

[0210] External environment control: Set and adjust the external temperature and humidity, record the external and internal temperature and humidity data of the equipment, and set the equipment's working state and start / stop state.

[0211] Temperature and humidity data recording: Record the humidity and temperature data of the air inside the equipment and the temperature of the inner surface of the equipment at different locations to ensure the time synchronization of the data.

[0212] Calculation of diffusion coefficient: The baseline moisture diffusion coefficient D0 was calculated using the half-life method, and the influence functions of temperature f(T) and humidity f(RH) were fitted using experimental data.

[0213] 1.4 Experimental Parameters and Measurement Methods:

[0214] Internal temperature and humidity of the equipment: Temperature and humidity sensors and thermocouples are placed in multiple key locations to ensure the acquisition of humidity and temperature data of the air inside the equipment, as well as the temperature of the internal surfaces of the equipment.

[0215] External ambient temperature and humidity: The environmental control system is used to adjust and record the external temperature and humidity in real time.

[0216] Humidity change rate: Calculate the half-life of humidity change at each location and calculate the diffusion coefficient D.

[0217] Data synchronization: Use a data acquisition system to synchronously record data from each sensor.

[0218] Fitting :

[0219] Objective: To fit the influence function of temperature and humidity on the diffusion coefficient using the data from the first stage.

[0220] Methods: Regression analysis was used to fit the effects of temperature and humidity on the diffusion coefficient.

[0221] Phase 2: Experiments with humidity-regulating materials:

[0222] 2.1 Objective: Through multiple tests, the same mass of humidity-regulating material is placed at different locations each time, and its influence on the moisture diffusion coefficient D is measured to fit the influence coefficient of the humidity-regulating material.

[0223] 2.2 Experimental conditions:

[0224] Humidity conditioning material: Select a humidity conditioning material with known moisture absorption / release properties, and maintain the same weight of humidity conditioning material for each experiment. The initial dosage is calculated at 600 g / m³, which will also be the amount to be optimized later.

[0225] Equipment operating state and start / stop state: Repeat the experimental conditions of stage 1 to ensure that the experiment is carried out under different external temperature and humidity conditions.

[0226] 2.3 Experimental Procedure:

[0227] Equipment preparation: In the same equipment as in stage 1, select different test locations and place the same weight of conditioning material.

[0228] External environment control: Set and record external temperature and humidity conditions in the equipment's working, dormant, and start / stop states to ensure consistency with stage 1.

[0229] Data recording: Real-time recording of temperature and humidity data at different locations inside the equipment, with particular attention to the location where humidity-regulating materials are placed.

[0230] Diffusion coefficient calculation: The diffusion coefficient of the conditioned material is calculated using the half-life method, and the difference between the diffusion coefficients of the conditioned material and the non-conditioned material is compared.

[0231] 2.4 Experimental Parameters and Measurement Methods:

[0232] Mass of humidification material: Use the same weight of humidification material for each experiment.

[0233] Temperature and humidity data: Same as in Phase 1, ensure that temperature and humidity data are collected synchronously at each location.

[0234] Moisture diffusion coefficient: The diffusion coefficient was calculated using the half-life method, and the results were compared with experimental data without moisture conditioning materials.

[0235] Using the data from the second stage, the influence function of the humidity-regulating material was fitted to describe the effect of humidity-regulating materials at different locations and with different weights on moisture diffusion. Based on the difference in moisture diffusion coefficients under conditions with and without humidity-regulating materials, the influence function of the humidity-regulating material on the diffusion coefficient was fitted.

[0236] This method has a sound theoretical basis and correct dimensions, and can utilize the half-life t. 1 / 2 The diffusion coefficient was inverted, and combined with temperature and humidity data and humidity-regulating materials, their respective influence parameters were further fitted, thus providing a quantitative basis for the subsequent design of internal humidity dynamics and anti-condensation of equipment.

[0237] The technical advantages of this embodiment are mainly reflected in the following aspects: First, by precisely controlling the mass and temperature / humidity data of the humidity-regulating material, the stability and repeatability of the experimental conditions are ensured, providing a foundation for the accurate calculation of the diffusion coefficient. Second, the half-life method is used to calculate the diffusion coefficient, which is not only simple but also accurate and reliable, truly reflecting the influence of the material on moisture diffusion. Finally, by fitting the influence function of the humidity-regulating material, the influence law of humidity-regulating materials at different locations and weights on moisture diffusion is successfully described, providing important quantitative basis for the dynamics of internal humidity and anti-condensation design of equipment. In summary, this embodiment has significant technical advantages and practical value.

[0238] Example 3

[0239] The difference between this embodiment and Embodiment 1 or Embodiment 2 is that the method further includes the following steps:

[0240] Step S5: Obtain the surface temperature inside the sealed cavity and determine the degree of condensation based on the humidity diffusion coefficient at the current location.

[0241] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for obtaining the moisture diffusion coefficient, based on a sealed cavity with a vent valve, wherein multiple measuring points are provided within the sealed cavity, characterized in that, The method includes the following steps: Obtain the diffusion distance from each measurement point to the vent valve; Obtain the temperature and humidity of the external environment of the sealed cavity within a preset time period; Obtain the temperature and humidity at various measurement points inside the sealed cavity within a preset time period; The moisture diffusion coefficient is calculated using the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity at each measurement point.

2. The method for obtaining the moisture diffusion coefficient according to claim 1, characterized in that, The process of obtaining the diffusion distance from each measurement point to the vent valve includes: establishing a three-dimensional coordinate system, obtaining the coordinates of the vent valve and each measurement point, and calculating the straight-line distance from the coordinates of the measurement point to the coordinates of the vent valve as the diffusion distance from the measurement point to the vent valve.

3. The method for obtaining the moisture diffusion coefficient according to claim 1, characterized in that, The process of calculating the moisture diffusion coefficient using the half-life method based on diffusion distance, temperature and humidity of the external environment of the sealed cavity, and temperature and humidity of each measurement point includes: combining different external environmental temperatures and humidity to calculate the moisture diffusion coefficient using the half-life method.

4. The method for obtaining the moisture diffusion coefficient according to claim 3, characterized in that, The process of calculating the moisture diffusion coefficient using the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measurement point includes: setting the external environment temperature to be the same, obtaining the moisture diffusion coefficient under different external environment humidity, calculating the humidity influence function, and thus fitting the moisture diffusion coefficient.

5. The method for obtaining the moisture diffusion coefficient according to claim 3, characterized in that, The process of calculating the moisture diffusion coefficient using the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measurement point includes: setting the external environment humidity to be the same, obtaining the moisture diffusion coefficient at different external environment temperatures, calculating the temperature influence function, and thus fitting the moisture diffusion coefficient.

6. The method for obtaining the moisture diffusion coefficient according to claim 1, characterized in that, The method further includes the following steps: after obtaining the humidity diffusion coefficient, obtaining the surface temperature inside the sealed cavity, and determining the degree of condensation based on the humidity diffusion coefficient at the current location.

7. The method for obtaining the moisture diffusion coefficient according to any one of claims 1 to 6, characterized in that, The method further includes the following steps: after changing the temperature and / or humidity, repeating the steps to obtain the temperature and humidity of the external environment of the sealed cavity within a preset time period; repeating the steps to obtain the temperature and humidity of each measurement point inside the sealed cavity within a preset time period; repeating the steps to calculate the moisture diffusion coefficient using the half-life method based on the diffusion distance, the temperature and humidity of the external environment of the sealed cavity, and the temperature and humidity of each measurement point, so as to obtain the moisture diffusion coefficient under different temperature and humidity conditions, and fit the influence function of temperature and humidity on the moisture diffusion coefficient.

8. A method for obtaining the moisture diffusion coefficient, characterized in that, The method includes the following steps: setting a humidity-regulating material at the measurement point, and obtaining the humidity diffusion coefficient when the humidity-regulating material is present at the measurement point through the steps of the humidity diffusion coefficient acquisition method according to any one of claims 1 to 7.

9. The method for obtaining the moisture diffusion coefficient according to claim 8, characterized in that, The method includes the following steps: obtaining the moisture diffusion coefficient at different locations and with different humidity-regulating materials, thereby fitting the influence function of the humidity-regulating material on the moisture diffusion coefficient.

10. The method for obtaining the moisture diffusion coefficient according to claim 9, characterized in that, The method includes the following steps: the humidity-regulating material placed at each location has the same weight.

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