## 3 Results and Discussions
### Analysis of Numerical Simulation
#### 3.1.3 Influence of the Spherical Coefficient on the Deposition Amount of Aerosol Particles
To enhance the validation of the numerical simulation results, it is crucial to provide a quantitative description of the total accumulation of particles on the adsorption membrane, as well as the accumulation in each individual region. Due to significant variations in  
Figure 11: Cloud map of surface particle deposition in photovoltaic field under different particle sizes. (**a**) \(d\) = 10 \(\upmu\)m; (**b**) \(d\) = 20 \(\upmu\)m; (**c**) \(d\) = 30 \(\upmu\)m.  
the particle input amount, inlet cross-sectional area, and deposition area between the experiment and simulation, the settling particle accumulation is separately normalized for each case. The normalized accumulation of particles settling is termed the unit deposition rate, which can be computed using Equation (13) [28]. \[\delta=\frac{q_{s}}{q_{in}}\times 100\% \tag{13}\]  
where \(q_{s}\) is the particle deposition density on the plate surface (kg/m\({}^{2}\)), which the calculated by Equation (14), and \(q_{in}\) is the particle release density (kg/m\({}^{2}\)), which is calculated by Equation (15). \[q_{s}=\frac{n}{A_{1}} \tag{14}\]  
where \(n\) is the particle deposition amount on the plate surface (kg), and \(A_{1}\) is the deposition area (m\({}^{2}\)). In the numerical simulation, \(A_{1}\) is the windward area of the photovoltaic module, which is 1.64 m\({}^{2}\). In the experiment, \(A_{1}\) is the sum of the areas of the 25 adsorption films, which is 0.25 m\({}^{2}\). \[q_{in}=\frac{m}{A_{2}} \tag{15}\]  
where \(m\) is the particle release amount (kg), and \(A_{2}\) is the release area (m\({}^{2}\)). In the numerical simulation, \(A_{2}\) is the inlet area of the photovoltaic field, which is 119.53 m\({}^{2}\). In the experiment, \(A_{2}\) is the inlet area of the wind tunnel power section, which is 12.56 m\({}^{2}\). The unit deposition rate of aerosol particles with a particle size of 30 \(\upmu\)m was fitted by a regression correlation equation, as shown in Equation (16). The coefficient of determination of Equation (16) was close to 1, indicating that the regression correlation equation was reliable. According to Equation (16), the normalized deposition coefficient of aerosol particles with a particle size of 30 \(\upmu\)m was 0.055%, and the intercept deposition rate was 4.2016%. \[\delta=0.00055\psi+0.042\,\left(\mathrm{R}^{2}=0.9948\right) \tag{16}\]  
Substituting the sphericity factors of three types of sand particles into Equation (16) allows us to obtain predicted values of the unit deposition rate for each corresponding sphericity factor. Substituting the predicted and experimental values of the three types of sand particles into Equation (17) enables us to determine the distribution of prediction errors for the regression equation. This process aids in verifying the reliability of the numerical simulation. Figure 12 demonstrates that under identical sphericity factor conditions, there is a consistent trend between the experimental and simulation results: the unit deposition rate increases as the sphericity factor increases. This indicates the reliability of the numerical simulation results. However, there are still some discrepancies between the simulation and experimental results, with a maximum error of 11.86%. The differences may be attributed to the following:  
1. A deviation exists between the flow field inside the wind tunnel and the simulated flow field. The flow field from the dynamic section to the contraction section exhibits non-uniformity, with the latter section having a larger diameter, leading to a lower wind speed compared to the set value of 3.5 m/s in the closed section. Consequently, a discrepancy occurs between the particle deposition characteristics and the simulation, specifically within the dynamic and contraction sections;
2. To simplify the model and reduce computational complexity, the particle phase was directly defined as dilute in the simulation. The assumption was made that there is no collision or agglomeration of particles during their motion with the airflow.