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Fundamentals of Liquid Interactions with Nano/Micro Engineered Surfaces at Low Temperatures

Abstract Details

, Master of Science, University of Toledo, Mechanical Engineering.
Superhydrophobic surfaces execute self-cleaning, anti-icing, and modifying heat transfer in many technological and industrial applications. In quest of maximizing water repellency, modification of droplet dynamics and subsequent reduction of contact time have been achieved by incorporating macrotexture on the superhydrophobic surfaces. However, the dynamics of low temperature water, and other viscous liquid droplets impacting anti-wetting surfaces with macrotextures is not well explored. In this thesis, we study the effect of viscosity on the bouncing dynamics of liquid droplets impacting macrotextured superamphiphobic surfaces using various glycerol-water mixtures as model liquids at different impacting conditions. Macrotextured surface are made by using an anti-wetting spray coating along with a tinned-copper wire as ridge on the silicon substrate. The complexity of viscous dissipation along the macrotexture and on the superamphiphobic surface is studied experimentally and then a new model is proposed for understanding when the macrotexture can induce maximum repellency of the viscous liquids on the superamphiphobic surfaces. A universal model for predicting minimum impact velocity for splitting is developed considering the droplet viscosity, velocity, volume, and other important parameters along with the surface characteristics and the macrotexture size. This enables engineering of surfaces for repelling droplets of viscous liquids such as freezing rain or inks during inkjet printing. Moreover, we studied the potentiality of superhydrophobic highly porous carbon nanotube (CNT) micropillars coated by the ultrathin, conformal, and low-surface-energy layer of poly (1H,1H,2H,2H-perfluorodecyl acrylate) (pPFDA) surfaces in condensation and freezing conditions (at high humidity). Droplet impact dynamics, condensate characteristics and freezing time delays are investigated on the CNT micropillars with various geometry along with the CNT forest and other commercially available anti-wetting coatings. Different wetting states (Cassie and Wenzel) of the coalesced condensate drops are observed on CNT micropillars with different solid area fractions and heights. In the low temperature and humid surroundings, CNT micropillars with the favorable topological configuration demonstrate complete droplet bouncing, significant freezing delays and considerable durability during several icing/de-icing cycles. This study provides understanding on the preferable geometry of the highly porous CNT micropillars for retaining hydrophobicity and preventing ice formation in the low temperature environments.
Hossein Sojoudi (Committee Chair)
Reza Rizvi (Committee Member)
Ana C. Alba Rubio (Committee Member)

Recommended Citations

Citations

  • Raiyan, A. (2018). Fundamentals of Liquid Interactions with Nano/Micro Engineered Surfaces at Low Temperatures [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo154471832751114

    APA Style (7th edition)

  • Raiyan, Asif. Fundamentals of Liquid Interactions with Nano/Micro Engineered Surfaces at Low Temperatures . 2018. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo154471832751114.

    MLA Style (8th edition)

  • Raiyan, Asif. "Fundamentals of Liquid Interactions with Nano/Micro Engineered Surfaces at Low Temperatures ." Master's thesis, University of Toledo, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo154471832751114

    Chicago Manual of Style (17th edition)