Abstract

An analytical model is developed to quantify the heat transfer to droplets impinging on heated superhydrophobic (SH) surfaces. Integral analysis is used to incorporate an apparent temperature jump at the superhydrophobic surface as a boundary condition. This Thesis considers the scenario of both isotropic and anisotropic slip, as would be realized on post-cavity style and rib-cavity style SH surfaces. This thermal model is combined with a hydrodynamic model which incorporates velocity slip at the surface. Use of the two models allows determination of the overall cooling effectiveness, a metric outlined in contemporary work. The effect of varying velocity slip and temperature jump is determined for impact Weber numbers ranging from 20 to 150 and surface temperatures ranging from 60 to 100°C. The model results are compared to experiments and good agreement is shown. Heat transfer to a drop impacting superhydrophobic surfaces is decreased when compared to conventional surfaces. A correlation function for the total heat transfer (cooling effectiveness) as a function of relevant parameters is found for isotropic surfaces with a good fit. Anisotropic rib-cavity surfaces are compared to isotropic surfaces to explore the impact of anisotropic slip on the cooling effectiveness, with similar trends seen to that for isotropic surfaces. It's determined that anisotropic surfaces can be modeled with minimal error as an isotropic surface with a temperature jump length equal to the anisotropic surface's average temperature jump length.

Degree

College and Department

Ira A. Fulton College of Engineering and Technology; Mechanical Engineering

Rights

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