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Thin Film Evaporation Modeling of the Microlayer Region in a Dewetting Water Bubble

Lakew, Ermiyas
http://orcid.org/0000-0002-3206-9067
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668618374937057

Abstract Details

2022, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Understanding the mechanism of bubble nucleation and growth is critical for optimizing the boiling heat transfer process. The microlayer region formed under the bubble departure is known to be a major contributor to phase change heat transfer but its evolution, spatio-temporal stability, and impact on macroscale bubble dynamics are still relatively unknown. In the thin film microlayer region, the vapor pressure is balanced by a combination of capillary, disjoining, and liquid pressures. Thermally driven evaporation in the curved thin film is suppressed by disjoining pressure at the nanoscale leading to a peak in evaporation flux in the microlayer region. Using a lubrication approximation coupled with conservation laws and the augmented Young-Laplace equation, 3rd order nonlinear film evolution equation is obtained. The evolution equation is solved numerically using the ODE 45 method in MATLAB. A variable wall temperature boundary condition is employed at the solid-liquid interface and is balanced by evaporative heat loss at the liquid-vapor interface. Contrary to most models, the solution begins in the thicker region of the film and proceeds in the direction of reducing film thickness. The solution method is devoid of tuning parameters or guessed inputs. Experimentally measured film thickness and its derivatives are used as inputs in the thicker region and the model is evaluated to obtain a film profile down to the nanoscale and a corresponding local evaporative flux. The modeling results compare favorably with spatio-temporal experimental measurements of the microlayer. By comparing the film profiles at multiple time steps, the accommodation coefficient could be estimated and its influence on the evaporative flux distribution is discussed.
Kishan Bellur, Ph.D. (Committee Member)
Raj Manglik, Ph.D. (Committee Member)
Milind Jog, Ph.D. (Committee Member)
80 p.
Mechanical Engineering
Thin Film Evaporation; Microlayer; Evaporation; Accommodation Coefficient

Recommended Citations

Citations

  • Lakew, E. (2022). Thin Film Evaporation Modeling of the Microlayer Region in a Dewetting Water Bubble [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668618374937057

    APA Style (7th edition)

  • Lakew, Ermiyas. Thin Film Evaporation Modeling of the Microlayer Region in a Dewetting Water Bubble. 2022. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668618374937057.

    MLA Style (8th edition)

  • Lakew, Ermiyas. "Thin Film Evaporation Modeling of the Microlayer Region in a Dewetting Water Bubble." Master's thesis, University of Cincinnati, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1668618374937057

    Chicago Manual of Style (17th edition)

ucin1668618374937057
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This open access ETD is published by University of Cincinnati and OhioLINK.