Analysis of the nucleation of nanofluids in the ice formation process

This paper presents a study on the impact of the wettability between the nanofluids and the metallic surface on the ice nucleation. The nanofluids consist of a basic liquid and the additive nanoparticles. Pure water is used as the basic fluid, and the nanoparticles, such as α-Al2O3, γ-Al2O3 and SiO2, are used as the additives. Three stainless steel vessels, in which the cooling surface has the roughness of 0.149μm, 0.433μm, and 0.729μm, respectively, were used to achieve different wettablities. Based on the relationship between the contact angle (θ) and the critical nucleation radius (r∗), the nucleation mechanism on the metallic surface has been improved. When the cooling surface of the vessel is hydrophilic, the change of the contact angle (θ) would impose a greater influence on the critical nucleation radius (r∗) compared with when the surface is hydrophobic, resulting in a great change of the temperature at rupture of supercooling (TRSC). And through adding different nanoparticles into the pure water, the different effects on decreasing the supercooling degree (ΔTSC) were observed, which strongly lies on the wettability and the crystal structure similarity between the ice and the additives.