Optical Properties of Spherical Silica-Based Greenhouse Coatings
Comparing Experimental Measurements with Monte Carlo Simulations
R.M. Ingham (TU Delft - Applied Sciences)
P. Dorenbos – Graduation committee member (TU Delft - Applied Sciences)
M.C. Goorden – Graduation committee member (TU Delft - Applied Sciences)
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Abstract
This thesis investigates the optical properties of monodisperse spherical silica-based coatings through experimental measurements and Monte Carlo ray tracing simulations. The aim is to compare these experiments and simulations to identify potential improvements. The study focuses on quantifying diffusivity and transmittance, related to Hortiscatter (HS) and Hemispherical Light Transmission (HLT), respectively, which are essential for optimizing greenhouse light conditions to enhance plant growth.
For HLT, simulations and measurements aligned more closely for low-scattering coatings, especially with smaller particles (160 nm and 400 nm), often showing less than 1% difference. However, for high-scattering coatings with larger particles, the difference was much larger, reaching up to 9%. This discrepancy highlights the possible importance of surface scattering and potential measurement setup limitations, such as the beam size being too small.
Significant discrepancies were observed between measured and simulated HS values, with measured values consistently higher by 5% to 80%, likely due to simulations not accounting for surface roughness. Smaller particles showed similar wavelength dependence of HS between simulation and measurement, while larger particles (5 μm) indicated the presence of complex scattering interactions that simulations did not account for.
Future work should refine simulation models to include surface roughness and obtain precise input parameters, such as refractive indices, to improve accuracy. Enhancing experimental setups, for example by reducing the signal-to-noise ratio, will also ensure more reliable measurements. This research offers valuable insights into optimizing greenhouse coatings, demonstrating the potential of theoretical models to predict practical outcomes under specific conditions. Continued advancements in simulation and experimental methodologies are crucial for effective greenhouse design to enhance plant growth.