Dust deposition numerical simulation method considering rainfall influence

Abstract

The invention discloses a dust deposition numerical simulation method considering rainfall influence. The method comprises the following steps: establishing a dust deposition numerical model, establishing a rainfall influence model, establishing a dust deposition dynamic model, and performing numerical simulation calculation. According to the method, the influence of rainfall on dust deposition can be quantified in numerical simulation, the complex dynamic process of dust deposition can be reflected more truly and accurately, the precision and applicability of dust deposition simulation are remarkably improved, the scientificity and reliability of the simulation method are ensured, meanwhile, good expandability is achieved, and the method is suitable for popularization and application. The method can meet the requirements of different regions and different scenes, and provides accurate data support for decision making in multiple fields of environmental protection, constructional engineering, industrial production and the like.

Description

Technical Field

[0001] The present invention relates to photovoltaic module operation and maintenance, air pollution control and environmental impact assessment technology, and in particular to a dust deposition numerical simulation method considering the influence of rainfall. Background Art

[0002] The study of dust deposition is of great significance in fields such as atmospheric environmental science, building maintenance, industrial production, and electronic equipment heat dissipation. Dust accumulation not only exacerbates air pollution and increases the risk of respiratory diseases, but also leads to surface degradation of buildings, reduced performance of mechanical equipment, and decreased heat dissipation efficiency of electronic devices. Traditional numerical simulation methods for dust deposition consider a limited number of influencing factors and typically operate on a monthly time scale, making it difficult to reflect the dynamic impact of diurnal variations in environmental factors on the deposition process.

[0003] In actual natural environments and industrial scenarios, rainfall is a frequent factor that significantly interferes with dust deposition. On the one hand, rainfall can remove deposited dust through a scouring effect; on the other hand, rainfall amount directly affects the probability of dust deposition collisions. However, existing numerical simulations ignore the multidimensional impact of rainfall on the dust deposition process. Due to the lack of quantitative characterization of rainfall interference mechanisms, traditional numerical simulation methods have difficulty accurately simulating the dust deposition patterns in real scenarios, resulting in significant discrepancies between predicted results and actual conditions. Therefore, there is an urgent need to develop a numerical simulation method for dust deposition that considers the influence of rainfall. Summary of the Invention

[0004] In view of the above-mentioned problems existing in the numerical simulation of dust deposition, the present invention provides a numerical simulation method for dust deposition that takes into account the influence of rainfall, so as to solve the problem that the existing technology cannot comprehensively and accurately simulate the influence of rainfall on dust deposition. It can quantify the impact of rainfall on dust deposition in numerical simulation and improve the accuracy of dust deposition result prediction.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions: A numerical simulation method for dust deposition considering the influence of rainfall, the steps of which are as follows:

[0006] 1) Establish a numerical model of dust deposition:

[0007] Construct a continuous phase model of the flow field based on CFD (computational fluid dynamics) method;

[0008] Establish a dust discrete phase model based on CFD method;

[0009] Establish a geometric model of the dust deposition process;

[0010] Meshing;

[0011] Parameter settings;

[0012] Boundary condition setting;

[0013] 2) Constructing a rainfall impact model:

[0014] When P(t)≤P min When ψ(t)=0;

[0015] When P min <P(t)≤P max When ψ(t)=a+bP(t)+cP 2 (t);

[0016] When P(t)>P max When ψ(t)=0.95;

[0017] Where: P min is the maximum rainfall for ineffective cleaning, P max is the minimum rainfall for almost complete cleaning, P(t) is the rainfall, a, b and c are the fitting coefficients of the rainfall cleaning coefficient and rainfall;

[0018] 3) Establish a dynamic model of dust deposition:

[0019] In the initial stage of the simulation, the dust deposition contact surface is clean, and the number of dust particles stored in the UDM (user-defined memory) is 0;

[0020] During the simulation, dust particles gradually deposit, and the deposited dust is stored in the UDM;

[0021] When the next dust particle reaches the grid, a random number between 0 and 1 is randomly generated using the Rand function, and the random number is compared with the dust coverage to determine the dust collision object;

[0022] The dust coverage is equal to the ratio of the projected area of the deposited dust to the area of the contact surface of the dust deposition, as shown in the following formula:

[0023]

[0024] Where: N d is the number of deposited dust particles, L1 and L2 are the length and width of the dust deposition contact surface, respectively;

[0025] Assuming the dust particles are of the same size and do not deform, they are initially evenly distributed and the single layer of dust particles is in the loosest arrangement when in contact with each other.

[0026] The maximum coverage of a single layer of dust on the dust deposition contact surface is N m ;

[0027] When the dust deposition contact surface is clean, the dust coverage is 0, and the dust will only collide with the dust deposition contact surface. As the dust is deposited, the dust coverage gradually increases, and the dust may collide with the dust deposition contact surface or with the deposited dust. When the dust coverage reaches N m Finally, dust will only collide with dust;

[0028] Assuming that rainfall is completed instantaneously at the node of two unit time, rainfall will not affect the dust deposition process, but only affect the dust deposition results;

[0029] Taking t as the unit time, the dust deposition amount from t-1 to t is:

[0030]

[0031] When it rains at the tth unit time, the dust deposition amount starting from the t+1th unit time is:

[0032]

[0033] The dust coverage per unit time based on the influence of rainfall will be updated as follows:

[0034]

[0035] Dust coverage is also calculated as the probability of dust colliding with already deposited dust;

[0036] The Rand function is used to randomly generate a random number ξ between 0 and 1 as the probability threshold for dust to collide with deposited dust. ξ is compared with N to determine the dust collision target. If N ≥ ξ, the dust collides with deposited dust; otherwise, it collides with the surface of the photovoltaic module. If rainfall occurs during this process, N is updated to N' and substituted into the calculation.

[0037] If dust particles are deposited on already deposited dust, the dust deposition area will not change. When dust collides with the dust deposition contact surface and deposits, the dust deposition area will increase and the coverage N will increase.

[0038] 4) Numerical simulation calculation:

[0039] Numerical simulation calculation and statistics of dust deposition rate.

[0040] A numerical simulation method for dust deposition considering the influence of rainfall is applied to realize the numerical simulation of dust deposition under the influence of rainfall.

[0041] The present invention can quantify the impact of rainfall on dust deposition in numerical simulations, can reflect the complex dynamic process of dust deposition more realistically and accurately, significantly improve the accuracy and applicability of dust deposition simulation, ensure the scientific nature and reliability of the simulation method, and at the same time has good scalability and can adapt to the needs of different regions and different scenarios, providing accurate data support for decision-making in multiple fields such as environmental protection, construction engineering, and industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the arrangement of dust particles when they come into contact with each other in the embodiment of the present invention;

[0043] Figure 2 Schematic diagram of the cleaning effect of rainfall on dust deposition in an embodiment of the present invention;

[0044] Figure 3 2. This is a schematic diagram of dust collision probability in an embodiment of the present invention;

[0045] Figure 4 This is a numerical simulation calculation process for dust deposition taking into account the influence of rainfall in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to the accompanying drawings and examples of dust deposition on the surface of photovoltaic modules. Figures 1 to 4 .

[0047] A numerical simulation method for dust deposition considering the influence of rainfall is proposed. The specific implementation steps are as follows:

[0048] Step 1: Establish a numerical model of dust deposition on the surface of photovoltaic modules:

[0049] Establishing a numerical model of dust deposition on the surface of photovoltaic modules includes establishing a flow field continuous phase model, a dust discrete phase model, a geometric model of the dust deposition process, meshing, parameter setting, and boundary condition setting.

[0050] The geometric model is as follows: establishing a geometric model of dust deposition contact objects and setting the calculation domain size;

[0051] The grid division: ensures calculation accuracy and improves calculation efficiency, and performs grid independence verification;

[0052] The parameter setting is to set the physical property parameters of the photovoltaic module surface, dust particles and air;

[0053] The boundary conditions are set as shown in Table 1;

[0054] Table 1 Boundary condition settings

[0055] area Boundary conditions Inlet Velocity-inlet Outlet Outflow Calculation domain bottom, photovoltaic module No-slipwall Other surfaces Symmetry Photovoltaic module surface Dustcapturesurface

[0056] Step 2: Build a rainfall impact model:

[0057] When the rainfall exceeds the minimum rainfall for essentially complete cleaning, the cleaning efficiency of the dust particles deposited on the dust deposition contact surface is 95%; when the rainfall is less than the maximum rainfall for ineffective cleaning, the number of dust particles deposited on the dust deposition contact surface remains unchanged; when the rainfall is between the maximum rainfall for ineffective cleaning and the minimum rainfall for essentially complete cleaning, the number of dust particles deposited on the dust deposition contact surface has a certain cleaning effect;

[0058] The unit time is selected as one day to establish the relationship between rainfall and rainfall cleaning coefficient. According to the monitoring results of the relationship between actual dust accumulation and cumulative dust accumulation and rainfall over time, it can be seen that 1mm is the maximum rainfall for ineffective cleaning, and 8mm is the minimum rainfall for basically complete cleaning.

[0059] The rainfall impact model is:

[0060] When P(t)≤1, ψ(t)=0;

[0061] When 1<P(t)≤8, ψ(t)=-0.055+0.045P(t)+0.01P 2 (t);

[0062] When P(t)>8, ψ(t)=0.95;

[0063] Step 3: Establish a dynamic model of dust deposition:

[0064] The maximum coverage rate of a single layer of dust on the dust deposition contact surface N m For (such as Figure 1 shown):

[0065]

[0066] The cleaning cycle of photovoltaic modules is T p ,After cleaning, the dust deposit on the surface of the photovoltaic module is cleared;

[0067] Rainfall is completed instantly at the node of two unit time. Rainfall does not affect the dust deposition process, but only affects the dust deposition results (such as Figure 2 shown);

[0068] Dust coverage is also calculated as the probability of dust colliding with already deposited dust;

[0069] When the surface of the photovoltaic module is clean, dust will only collide with the surface of the photovoltaic module, and the probability of collision with dust is 0;

[0070] As dust settles, the probability N of dust colliding with deposited dust gradually increases until N ≥ N m,At this time, the probability of dust colliding with deposited dust is 100%, otherwise, dust may collide with the surface of the photovoltaic module or with the deposited dust;

[0071] The Rand function is used to randomly generate a random number ξ between 0 and 1 as the probability threshold of dust collision with deposited dust;

[0072] Compare ξ with N to determine the dust collision object. If N ≥ ξ, the dust collides with the deposited dust, otherwise it collides with the surface of the photovoltaic module.

[0073] If it rains during this process, N will be updated to N' and substituted into the calculation (e.g. Figure 3 shown);

[0074] Dust particles are deposited on the deposited dust, and the dust deposition area does not change. When dust collides with the surface of the photovoltaic module and deposits, the dust deposition area will increase and the coverage N will increase (e.g. Figure 4 shown).

[0075] Step 4: Numerical simulation calculation:

[0076] Numerical simulation calculation and statistics of dust deposition rate.

[0077] A numerical simulation method for dust deposition that considers rainfall effects has been applied to predict the power generation of photovoltaic systems under dust deposition conditions. The standard deviation of the relative error of the predicted power generation without considering rainfall is 13.3, while the standard deviation of the predicted power generation with considering rainfall is 10.7, a reduction of approximately 19.5%.

Claims

1. A numerical simulation method for dust deposition considering the influence of rainfall, characterized in that: The following steps are involved: 1) Establish a numerical model of dust deposition: Construct a continuous phase model of the flow field based on the CFD method; Establish a dust discrete phase model based on CFD method; Establish a geometric model of the dust deposition process; Meshing; Parameter settings; Boundary condition setting; 2) Constructing a rainfall impact model: When P(t)≤P min When ψ(t)=0; When P min <P(t)≤P max When ψ(t)=a+bP(t)+cP 2 (t); When P(t)>P max When ψ(t)=0.95; Where: P min is the maximum rainfall for ineffective cleaning, P max is the minimum rainfall for almost complete cleaning, P(t) is the rainfall, a, b and c are the fitting coefficients of the rainfall cleaning coefficient and rainfall; 3) Establish a dynamic model of dust deposition: In the initial stage of the simulation, the dust deposition contact surface is clean and the number of dust particles stored in the UDM is 0; During the simulation, dust particles gradually deposit, and the deposited dust is stored in the UDM; When the next dust particle reaches the grid, a random number between 0 and 1 is randomly generated using the Rand function, and the random number is compared with the dust coverage to determine the dust collision object; The dust coverage is equal to the ratio of the projected area of the deposited dust to the area of the contact surface of the dust deposition, as shown in the following formula: Where: N d is the number of deposited dust particles, L1 and L2 are the length and width of the dust deposition contact surface, respectively; Assuming the dust particles are of the same size and do not deform, they are initially evenly distributed and the single layer of dust particles is in the loosest arrangement when in contact with each other. The maximum coverage of a single layer of dust on the dust deposition contact surface is N m ; When the dust deposition contact surface is clean, the dust coverage is 0, and the dust will only collide with the dust deposition contact surface. As the dust is deposited, the dust coverage gradually increases, and the dust may collide with the dust deposition contact surface or with the deposited dust. When the dust coverage reaches N m Afterwards, dust will only collide with dust; Assuming that rainfall is completed instantaneously at the node of two unit time, rainfall will not affect the dust deposition process, but only affect the dust deposition results; Taking t as the unit time, the dust deposition amount from t-1 to t is: When it rains at the tth unit time, the dust deposition amount starting from the t+1th unit time is: The dust coverage per unit time based on the influence of rainfall will be updated as follows: Dust coverage is also calculated as the probability of dust colliding with already deposited dust; The Rand function is used to randomly generate a random number ξ between 0 and 1 as the probability threshold for dust to collide with deposited dust. ξ is compared with N to determine the dust collision target. If N ≥ ξ, the dust collides with deposited dust; otherwise, it collides with the surface of the photovoltaic module. If rainfall occurs during this process, N is updated to N' and substituted into the calculation. If dust particles are deposited on already deposited dust, the dust deposition area will not change. When dust collides with the dust deposition contact surface and deposits, the dust deposition area will increase and the coverage N will increase. 4) Numerical simulation calculation: Numerical simulation calculation and statistics of dust deposition rate.

2. The dust deposition numerical simulation method considering the influence of rainfall according to claim 1 is characterized in that: Applied to realize numerical simulation of dust deposition affected by rainfall.

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