In this master’s thesis the influence of surface wettability, thermal effusivity of the substrate and the impact velocity of water droplets on their freezing behaviour was researched. The research framework aimed at covering a broad range of surface wettability and substrate thermal effusivity, as well as a wide interval of droplet impact velocities, was established based on a literature review. In order to achieve varying degrees of wettability, we developed a range of surface coatings synthesised using diverse functional components, including nanoparticles, surfactants, and organic compounds, with a polymer acting as the matrix. The developed coatings achieved contact angles ranging from 5° to 152°, but only those based on hybrid polymer solutions and coated with a thin gold layer, proved sufficiently resistant to repeated freezing. By tracking the evolution of the spreading factor and recording its maximum and final values, we determined the influence of thermal effusivity using aluminium, titanium, and polymer PEEK substrates, and the effect of wettability using hybrid coatings. We demonstrated that higher substrate thermal effusivity shortens the time of droplet freezing and increases the likelihood of freezing before contraction completes, while surface wettability mainly affects the contraction phase and final droplet diameter. Comparison of the experimental results with theoretical models from the literature revealed consistent outcomes.
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