ORCID

0000-0002-8274-4657

Keywords

Spray Cooling, Evaporation, Dispersion, Thin Film, Capillary

Abstract

Droplet evaporation plays a vital role in spray cooling applications, helping to maintain safe operating temperatures for high-powered devices such as lasers and supercomputers. There exists an ongoing debate regarding the appropriateness of diffusion-limited versus kinetically limited models for describing this complex process. This work seeks to bridge the macro-scale evaporation, governed primarily by capillary forces, with the nano-scale interactions among the vapor, liquid, and solid phases through a comprehensive description of disjoining pressure.

By integrating principles from lubrication theory, heat conduction, diffusion, and statistical methods, a detailed model for evaporative mass flux is developed. This model incorporates various interactions, including capillary, Van der Waals, structural, and electrostatic forces, while also illustrating how the thickness and thermal properties of thin films impact evaporation on low thermal conductivity substrates. Single droplet evaporation experiments conducted on pure copper and composite substrates, composed of metal thin films (copper, aluminum, and titanium) layered over fused silica, yield results that align closely with the proposed model, particularly for temperatures below saturation, where bubble formation is not considered.

Moreover, the investigation into single droplet evaporation is extended by applying statistical methods, specifically the gamma distribution, to analyze a wide array of non-interacting droplets evaporating on a heated substrate. This analysis leverages high-speed video recordings, infrared temperature measurements, and contour tracking. The findings exhibit strong agreement with the predictions from the single droplet evaporation model at temperatures below saturation, confirming the validity of the approach.

Completion Date

2025

Semester

Spring

Committee Chair

Putnam, Shawn

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Identifier

DP0029397

Document Type

Dissertation/Thesis

Campus Location

Orlando (Main) Campus

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