荒漠环境中电池板表面灰尘颗粒力学模型建立

高海拔荒漠地区电池板表面积灰严重制约着光伏发电效率和光伏组件寿命。该文在分析表面能的基础上，假设接触不变形条件下，依据宏观分子间作用理论分析提出了电池板表面灰尘颗粒粘附受力模型。结合青海共和地区电池板表面灰尘主要成分和粒径组成，给出了灰尘受力参数；计算了灰尘颗粒所受的范德华力、静电力及重力，给出由参数改变引起的灰尘受力的变化规律。结果表明：当灰尘颗粒半径较小时，颗粒与电池板间的主要粘附力为范德华力，当灰尘颗粒半径较大时，重力分量则成为主导粘附力，粘附合力取值范围为10-10～10-8 N；Lifshitz常数和分子间平均间距主要影响的是范德华力；灰尘颗粒总的静电力随灰尘颗粒半径的增大而增大，静电力的取值小于范德华力和重力分量。对灰尘粘附受力大小及其规律的研究，为高海拔荒漠地区光伏除尘提供理论依据。

Mechanics modeling of dust particle on solar panel surface in desert environment

Abstract: Along with the booming development of the photovoltaic industry, the later maintenance of photovoltaic power station and the improvement of photovoltaic power generation efficiency have gradually become the focus of attention. Under the condition of blown sand in high altitude desert areas, dust accumulation on the surface of solar panel has become one of the most significant factors which influences the consistency and efficiency of photovoltaic power station. The effects of dust deposition on photovoltaic conversion efficiency and dust removal methods were studied. The mechanism of dust particle adhesion was analyzed at first in this paper. Due to the surface free energy of the dust particle and solar panel, they interacted. The van der Waals force between spherical dust particles and the panel was derived from Lifshitz's macro molecular interaction theory and the order of magnitudes van der Waals force was calculated. The electrostatic image force was simulated based on two known dust charge empirical expressions. The relationship between the radius of dust particle and the double layer electrostatic force was investigated by taking different values of the contact potential difference, which ranged from 0 to 0.5 V. Compared with the dust particle, the solar panel surface can be taken as an infinite disk. The relationship between the parameters and electric field force was obtained. Meanwhile, the gravity of dust particle was analyzed when the photovoltaic panels were mounted with an angle with respective to the horizontal plane. Through the analyses of all interactive forces, the conclusions that Van der Waals force of dust particle increased with increasing of the surface free energy were drawn. The dust particle radius ranged from 0.2×10-6 to 40×10-6 m, and the distance between molecules ranged from 10-9 to 10-7 m. Combined with Lifshitz constant (0.96-14.4 eV), the magnitude of dust van der Waals force was calculated as 10-10-10-9 N. The magnitudes of electrostatic image force and double layer electrostatic force were calculated as 10-13-10-12 N based on the charges (10-18-10-16 C) of dust surface and the contact potential difference (0-0.5 V). The radius of dust and the distance between molecules had smaller effects on the electrostatic image force and double layer electrostatic force than electrostatic image force. The dust particle radius R had no effects on the electric field strength. The electric field force increased with the increasing of R. The distance between molecules didn't affect the electric field force. The magnitude of electric field force was calculated as 0-10-13 N. The gravity of dust particle was affected by the radius and density of dust particle, and its magnitude was approximated as 10-10-10-9 N. The interactions between the dust particles were more complex, which was affected by the numbers of particles, the porous ratio, particle clearance and radius. Through analyzing all interactions between dust particle and solar panel surface, it is concluded that van der Waals force > gravity > electrostatic force when the dust radius was smaller (R<20×10-6 m), and gravity > van der Waals force > electrostatic force when the dust radius was larger (R>20×10-6 m). The adhesion force between the dust particle and solar panel surface increased with the increasing of dust radius, and its magnitude ranged from 10-10 to 10-8 N. In the dry and windy desert area, the combination of gravity and van der Waals force plays an important role without considering the chemical interactions.