Droplet evaporation on functional surfaces

A. Alperen Günay, Marisa Gnadt, Soumyadip Sett, Junho Oh, Nenad Miljkovic

Research output: Contribution to journalConference article

Abstract

Droplet evaporation is an important phenomenon governing many man-made and natural processes. Characterizing the rate of evaporation with high accuracy has attracted the attention of numerous scientists over the past century. Traditionally, researchers have studied evaporation by observing the change in the droplet size in a fixed time interval. However, the transient nature coupled with the significant mass-transfer governed gas-dynamics occurring at the droplet three-phase contact line make the classical method crude. Furthermore, the intricate balance played by the internal and external flows, evaporation kinetics, thermocapillarity, binary-mixture dynamics, curvature, and moving contact lines make the decoupling of these processes impossible with classical transient methods. Here, we use our recently developed spatially-steady method to characterize the rate of evaporation of sessile droplets on functional surfaces. By utilizing a piezoelectric dispenser to feed microscale droplets ( ≈ 9 µm) to a larger evaporating droplet at a prescribed frequency, we can both create variable-sized droplets on any surface, and study their evaporation rate by modulating the piezoelectric droplet addition frequency. Using the spatially-steady technique, we studied water evaporation of droplets having base radii ranging from 30 µm to 270 µm on surfaces of different functionalities (45 ≤ a,app ≤ 162, where a,app is the apparent advancing contact angle) under different substrate temperature conditions (30℃ ≤ s ≤ 60℃, where s is the functional surface temperature). Our work shows that the rate of evaporation increases linearly for increasing droplet size, and the surface functionality halts its important role at elevated temperatures.

Original languageEnglish (US)
Pages (from-to)1285-1291
Number of pages7
JournalInternational Heat Transfer Conference
Volume2018-August
StatePublished - Jan 1 2018
Event16th International Heat Transfer Conference, IHTC 2018 - Beijing, China
Duration: Aug 10 2018Aug 15 2018

Keywords

  • Droplet
  • Evaporation
  • Functional surface
  • Measurement and instrumentation
  • Nano/micro
  • Surface temperature

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes
  • Condensed Matter Physics
  • Mechanical Engineering

Fingerprint Dive into the research topics of 'Droplet evaporation on functional surfaces'. Together they form a unique fingerprint.

  • Cite this

    Alperen Günay, A., Gnadt, M., Sett, S., Oh, J., & Miljkovic, N. (2018). Droplet evaporation on functional surfaces. International Heat Transfer Conference, 2018-August, 1285-1291.