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 language | English (US) |
|---|---|
| Pages (from-to) | 1285-1291 |
| Number of pages | 7 |
| Journal | International Heat Transfer Conference |
| Volume | 2018-August |
| State | Published - Jan 1 2018 |
| Event | 16th International Heat Transfer Conference, IHTC 2018 - Beijing, China Duration: Aug 10 2018 → Aug 15 2018 |
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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
Cite this
Droplet evaporation on functional surfaces. / Alperen Günay, A.; Gnadt, Marisa; Sett, Soumyadip; Oh, Junho; Miljkovic, Nenad.
In: International Heat Transfer Conference, Vol. 2018-August, 01.01.2018, p. 1285-1291.Research output: Contribution to journal › Conference article
}
TY - JOUR
T1 - Droplet evaporation on functional surfaces
AU - Alperen Günay, A.
AU - Gnadt, Marisa
AU - Sett, Soumyadip
AU - Oh, Junho
AU - Miljkovic, Nenad
PY - 2018/1/1
Y1 - 2018/1/1
N2 - 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.
AB - 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.
KW - Droplet
KW - Evaporation
KW - Functional surface
KW - Measurement and instrumentation
KW - Nano/micro
KW - Surface temperature
UR - http://www.scopus.com/inward/record.url?scp=85068349510&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85068349510&partnerID=8YFLogxK
M3 - Conference article
AN - SCOPUS:85068349510
VL - 2018-August
SP - 1285
EP - 1291
JO - International Heat Transfer Conference
JF - International Heat Transfer Conference
SN - 2377-424X
ER -