Abstract
To investigate the stationary nanofluid droplets effects ofsubstrate surface temperature and particle concentration on thefreezing time, deformation, and droplet contact angle during thefreezing process, high-speed CCD image observation was used tostudy the morphological changes during the freezing process of(TiO \({}_{2}\) –H \({}_{2}\) O) nanodroplets. Nanoparticle droplets wereprepared in this study using magnetic stirring and ultrasonicmixing. Three substrate surface temperatures (268, 265, and 263 K)and four concentrations of TiO \({}_{2}\) nanoparticles (5, 10, 30, and50 mg/mL) were considered. The findings demonstrate that theaddition of nanoparticles will result in the droplets appearingsanded, a considerable change in the form of the droplet tip, anda decrease in the release of bubbles upon freezing. The increasein supercooling at high concentrations ( \(>5\) mg/mL) causes thedroplet height to rise, its volume to expand upon freezing, andits shape to shift from ‘‘peach-core’’ to ‘‘cone-like.’’ WhenTiO \({}_{2}\) nanoparticles were added, the droplets’ longitudinalmorphology changed throughout the freezing process, but lateraldiffusion was unaffected, even though the contact angle \(\theta\) marginally shrank as concentration increased. The droplets withthe lowest concentration of TiO \({}_{2}\) particles exhibit thehighest longitudinal deformation rate \(\alpha\) during the dropletfreezing process. As the subcooling degree increases, \(\alpha\) also rises and reaches its maximum at 263 K or 22.26 \(\%\) , but asthe concentration of nanoparticles grows, \(\alpha\) drops, and sodoes the coefficient of segregation, \(\gamma\) .
