JP-7856342-B2 - Method for calculating the vapor diffusion coefficient of bound water in porous glass sand media

Inventors

• ▲ドウ▼ 智
• 王 錦国
• 楊 ▲ユン▼
• 陳 舟
• 張 建橋

Assignees

• 河海大学

Dates

Publication Date

20260511

Application Date

20240319

Priority Date

20231222

Claims (5)

1. A method for calculating the vapor diffusion coefficient of bound water in a porous glass sand medium, Step 1 involves calculating the total evaporation rate of the porous glass sand medium and the evaporation rate of bound water in the porous glass sand medium. Step 2 calculates the equivalent evaporation area of bound water in the porous glass sand medium based on the total evaporation rate of the porous glass sand medium and the evaporation rate of bound water in the porous glass sand medium. Step 3 involves establishing a dynamic relationship between the evaporation rate of bound water in a porous glass sand medium and the equivalent evaporation area of bound water in the porous glass sand medium, and constructing a functional relationship where the vapor diffusion coefficient of bound water in the porous glass sand medium is the dependent variable and the evaporation rate of bound water and the equivalent evaporation area of bound water in the porous glass sand medium are the independent variables. A method for calculating the vapor diffusion coefficient of bound water in a porous glass sand medium, comprising step 4, which involves calculating the vapor diffusion coefficient of bound water based on a functional relationship between the vaporization rate of bound water and the equivalent area of evaporation of bound water, by giving the vaporization rate of bound water and the equivalent area of evaporation of bound water.
2. Step 1 involves calculating the total evaporation rate of the porous glass sand medium and the evaporation rate of bound water in the porous glass sand medium. e = V(∂θ/∂t) e b = V(∂θ b / ∂t), A method for calculating the vapor diffusion coefficient of bound water in a porous glass sand medium according to claim 1, characterized in that e is the total evaporation rate, e b is the evaporation rate of bound water, V is the volume of the porous glass sand medium, θ is the total volume water content, θ b is the volume water content of bound water, t is the evaporation time, ∂θ/∂t is the change in total volume water content with respect to evaporation time, and ∂θ b /∂t is the change in volume water content of bound water with respect to evaporation time.
3. Step 2 is a method for calculating the equivalent evaporation area of bound water in a porous glass sand medium based on the total evaporation rate of the porous glass sand medium and the evaporation rate of bound water in the porous glass sand medium, And, A v is the equivalent area of bound water evaporation, A is the actual surface area of the porous glass sand medium, ψ is the porosity of the porous glass sand medium, ξ is the empirical reduction coefficient, σ is the interfacial tension of water, α is the contact angle between water and the glass sand surface, ρ w is the density of water, and g is the acceleration due to gravity. This is the average pore size of free water, The method for calculating the vapor diffusion coefficient of bound water in a porous glass sand medium according to claim 2, characterized in that is the amount of change in capillary rise height.
4. Step 3 involves establishing a dynamic relationship between the evaporation rate of bound water in a porous glass sand medium and the equivalent evaporation area of bound water in the porous glass sand medium. And, D is the vapor diffusion coefficient of bound water, C1 is the initial vapor concentration during the evaporation process, C∞ is the vapor concentration at the end of the evaporation process, Av is the equivalent evaporation area of bound water, and H is the height of the porous glass sand medium. A method for constructing a functional relationship where the vapor diffusion coefficient of bound water in a porous glass sand medium is the dependent variable, and the evaporation rate of bound water in the porous glass sand medium and the equivalent evaporation area of bound water in the porous glass sand medium are the independent variables is: The method for calculating the vapor diffusion coefficient of bound water in a porous glass sand medium according to claim 3.
5. Step 4 is characterized in that the constructed bound water vapor diffusion coefficient can be obtained by substituting the values given the bound water evaporation rate and the bound water vapor diffusion area into a glass sand porous medium, based on a functional relationship between the bound water evaporation rate and the equivalent evaporation area of the bound water. This is the method for calculating the bound water vapor diffusion coefficient of a glass sand porous medium according to claim 4.

Description

This invention belongs to the technical field of groundwater hydraulics in aeration zones, and more specifically, relates to a method for calculating the vapor diffusion coefficient of bound water in a porous glass sand medium. The diffusion coefficient is an important parameter representing the water transport capacity in a porous glass sand medium. For calculating the water diffusion coefficient of a porous glass sand medium, experimental methods and numerical simulations are typically used. The experimental method calculates the water diffusion coefficient by actually measuring the diffusion rate of water in a medium. This can be achieved using various experimental apparatuses and techniques, such as measuring the water transport rate through the medium. However, the experimental method requires a significant amount of time and resources because it necessitates performing numerous experiments to obtain sufficient data for analysis. Furthermore, limitations on experimental conditions, such as the control of elements like temperature, humidity, and pressure, also affect the feasibility of the experiment. On the other hand, numerical simulation methods use mathematical models and computers to simulate the diffusion process of water in a medium. This method involves establishing mathematical models of the medium structure and water transport, and then using a computer to simulate the water diffusion process and calculate the water diffusion coefficient. However, numerical simulation methods require accurate mathematical models and high-performance computers, resulting in high computational complexity and long computation times. Therefore, while these methods all have some use in calculating the water diffusion coefficient, they all ignore bound water, which is the main control factor of vapor diffusion, and the diffusion coefficient calculation is basically performed considering all pore water. Furthermore, problems such as limited experimental conditions, significant time and resource consumption, and high computational complexity are particularly pronounced. Therefore, further research and development of more efficient and accurate calculation methods are necessary to solve these problems. Figure 1 is a flowchart showing a method for calculating the vapor diffusion coefficient of bound water in a porous glass sand medium according to an embodiment of the present invention.Figure 2 shows the dynamic change in the vapor diffusion coefficient of bound water according to an embodiment of the present invention. The following describes specific embodiments of the present invention in more detail with reference to the drawings and examples. The following embodiments are used solely to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. As shown in Figure 1, the present invention proposes a method for calculating the vapor diffusion coefficient of bound water in a porous glass sand medium, specifically, Step 1 involves calculating the total evaporation rate of the porous glass sand medium and the evaporation rate of bound water in the porous glass sand medium. Step 2 calculates the equivalent evaporation area of bound water in the porous glass sand medium based on the total evaporation rate of the porous glass sand medium and the evaporation rate of bound water in the porous glass sand medium. Step 3 involves establishing a dynamic relationship between the evaporation rate of bound water in a porous glass sand medium and the equivalent evaporation area of bound water in the porous glass sand medium, and constructing a functional relationship where the vapor diffusion coefficient of bound water in the porous glass sand medium is the dependent variable and the evaporation rate of bound water and the equivalent evaporation area of bound water in the porous glass sand medium are the independent variables. The method includes step 4, which calculates the vapor diffusion coefficient of bound water based on the functional relationship between the vapor diffusion coefficient of bound water and the vaporization rate of bound water and the equivalent area of vaporization of bound water, by giving the vaporization rate of bound water and the equivalent area of vaporization of bound water. Furthermore, in step 1, the method for calculating the total evaporation rate of the porous glass sand medium and the evaporation rate of bound water in the porous glass sand medium is as follows: e = V(∂θ/∂t) e b =V(∂θ b /∂t) And, e is the total evaporation rate, e b is the evaporation rate of bound water, V is the volume of the glass sand porous medium, θ is the total volume water content, θ b is the volume water content of bound water, t is the evaporation time, ∂θ/∂t is the change in total volume water content with respect to evaporation time, and ∂θ b /∂t is the change in volume water content of bound water with respect to evaporation t