This paper quantifies experimentally the effect of pendant droplets condensed on the back of semi-transparent glass panes on their normal-hemispherical transmittance and reflectance in the visible and near-infrared. To enable sample characterization and ensure repeatability, acrylic droplets were deposited on the back side of 3 mm-thick soda-lime silicate glass slabs with or without hydrophobic surface treatment including perfluorinated silane, perfluorinated silane-coated silica nanoparticle monolayer, or Teflon coatings. The droplet contact angle θ_c was varied between 26° and 76° and the projected surface area coverage reached up to 60%. For contact angle θ_c smaller than the critical angle θ_cr for total internal reflection at the droplet/air interface, the presence of droplets did not significantly affect the normal-hemispherical transmittance and reflectance. However, for droplet contact angle θ_cr ≤ θ_c < 90°, the normal-hemispherical transmittance decreased significantly with increasing droplet contact angle and/or surface area coverage while the normal-hemispherical reflectance increased. The measurements of the normal-hemispherical transmittance were in excellent agreement with numerical predictions obtained from Monte Carlo Ray Tracing method. These results further validate our previous numerical simulations and the different optical regimes identified. The results of this study can provide guidelines for the design and operation of energy efficient flat-plate solar collectors, outdoor photobioreactors, greenhouses, solar desalination systems, and other solar energy conversion systems.

本文通过实验量化了半透明玻璃板背面凝结的悬垂液滴对可见光和近红外光的正常半球透射率和反射率的影响。为了能够进行样品表征并确保可重复性，丙烯酸滴状物沉积在3毫米厚的钠钙硅酸盐玻璃平板的背面，该表面经过或不经过疏水性表面处理，包括全氟化硅烷，全氟化硅烷涂覆的二氧化硅纳米粒子单层或特富龙涂层。液滴的接触角θ _Ç为76 26之间变化°和°和投影表面积覆盖率达到高达60％。接触角θ _Ç比临界角小的θ _CR对于液滴/空气界面处的全内反射，液滴的存在不会显着影响法向半球的透射率和反射率。然而，对于液滴的接触角θ _CR ≤ θ _Ç<90°，法向半球透射率随着液滴接触角和/或表面积覆盖率的增加而显着降低，而法向半球反射率则增加。法向半球透射率的测量与从蒙特卡洛射线追踪法获得的数值预测非常吻合。这些结果进一步验证了我们先前的数值模拟和确定的不同光学方案。这项研究的结果可以为节能平板太阳能收集器，室外光生物反应器，温室，太阳能脱盐系统和其他太阳能转换系统的设计和操作提供指导。