Numerical study of hydrophobic-island shapes with patterned wettability for pool boiling

Jung Shin Lee, Joon Sang Lee

Research output: Contribution to journalArticle

Abstract

Heat transfer during boiling is strongly affected by wettability pattern on the heater surface, and accordingly, has been actively studied. The wettability pattern comprises hydrophobic dots (islands) on a hydrophilic surface. Conventional hydrophobic dots are shaped like squares or circles. With these shapes, the contact line remains confined to the hydrophobic dot. On the other hand, by using a re-entrant dot shape, the contact line might invade the hydrophilic surface, depending upon the balance between the force required to pin the contact line to the hydrophobic dot and that required to maintain a circular contact line by surface tension. In the present study, we explore the use of crosses as the shapes of hydrophobic dots, with the aspect ratio of the arms of the cross used as a variable. The use of this re-entrant dot shape shows that the contact line does indeed invade the hydrophilic surface, as expected. The results show that the contribution of the triple-contact line to heat transfer increases with the aspect ratio. However, at low heat flux, we find a reduction in the effective nucleation area to be a side-effect of a large aspect ratio. Therefore, proper selection of the aspect ratio is needed for optimal heat transfer, depending on the amount of heat generated by the heat source.

Original languageEnglish
Pages (from-to)1632-1641
Number of pages10
JournalApplied Thermal Engineering
Volume127
DOIs
Publication statusPublished - 2017 Jan 1

Fingerprint

Boiling liquids
Wetting
Aspect ratio
Heat transfer
Surface tension
Heat flux
Nucleation
Hot Temperature

All Science Journal Classification (ASJC) codes

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

Cite this

@article{eb2029fabd44453287aa366db01fa758,
title = "Numerical study of hydrophobic-island shapes with patterned wettability for pool boiling",
abstract = "Heat transfer during boiling is strongly affected by wettability pattern on the heater surface, and accordingly, has been actively studied. The wettability pattern comprises hydrophobic dots (islands) on a hydrophilic surface. Conventional hydrophobic dots are shaped like squares or circles. With these shapes, the contact line remains confined to the hydrophobic dot. On the other hand, by using a re-entrant dot shape, the contact line might invade the hydrophilic surface, depending upon the balance between the force required to pin the contact line to the hydrophobic dot and that required to maintain a circular contact line by surface tension. In the present study, we explore the use of crosses as the shapes of hydrophobic dots, with the aspect ratio of the arms of the cross used as a variable. The use of this re-entrant dot shape shows that the contact line does indeed invade the hydrophilic surface, as expected. The results show that the contribution of the triple-contact line to heat transfer increases with the aspect ratio. However, at low heat flux, we find a reduction in the effective nucleation area to be a side-effect of a large aspect ratio. Therefore, proper selection of the aspect ratio is needed for optimal heat transfer, depending on the amount of heat generated by the heat source.",
author = "Lee, {Jung Shin} and Lee, {Joon Sang}",
year = "2017",
month = "1",
day = "1",
doi = "10.1016/j.applthermaleng.2017.08.092",
language = "English",
volume = "127",
pages = "1632--1641",
journal = "Applied Thermal Engineering",
issn = "1359-4311",
publisher = "Elsevier Limited",

}

Numerical study of hydrophobic-island shapes with patterned wettability for pool boiling. / Lee, Jung Shin; Lee, Joon Sang.

In: Applied Thermal Engineering, Vol. 127, 01.01.2017, p. 1632-1641.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Numerical study of hydrophobic-island shapes with patterned wettability for pool boiling

AU - Lee, Jung Shin

AU - Lee, Joon Sang

PY - 2017/1/1

Y1 - 2017/1/1

N2 - Heat transfer during boiling is strongly affected by wettability pattern on the heater surface, and accordingly, has been actively studied. The wettability pattern comprises hydrophobic dots (islands) on a hydrophilic surface. Conventional hydrophobic dots are shaped like squares or circles. With these shapes, the contact line remains confined to the hydrophobic dot. On the other hand, by using a re-entrant dot shape, the contact line might invade the hydrophilic surface, depending upon the balance between the force required to pin the contact line to the hydrophobic dot and that required to maintain a circular contact line by surface tension. In the present study, we explore the use of crosses as the shapes of hydrophobic dots, with the aspect ratio of the arms of the cross used as a variable. The use of this re-entrant dot shape shows that the contact line does indeed invade the hydrophilic surface, as expected. The results show that the contribution of the triple-contact line to heat transfer increases with the aspect ratio. However, at low heat flux, we find a reduction in the effective nucleation area to be a side-effect of a large aspect ratio. Therefore, proper selection of the aspect ratio is needed for optimal heat transfer, depending on the amount of heat generated by the heat source.

AB - Heat transfer during boiling is strongly affected by wettability pattern on the heater surface, and accordingly, has been actively studied. The wettability pattern comprises hydrophobic dots (islands) on a hydrophilic surface. Conventional hydrophobic dots are shaped like squares or circles. With these shapes, the contact line remains confined to the hydrophobic dot. On the other hand, by using a re-entrant dot shape, the contact line might invade the hydrophilic surface, depending upon the balance between the force required to pin the contact line to the hydrophobic dot and that required to maintain a circular contact line by surface tension. In the present study, we explore the use of crosses as the shapes of hydrophobic dots, with the aspect ratio of the arms of the cross used as a variable. The use of this re-entrant dot shape shows that the contact line does indeed invade the hydrophilic surface, as expected. The results show that the contribution of the triple-contact line to heat transfer increases with the aspect ratio. However, at low heat flux, we find a reduction in the effective nucleation area to be a side-effect of a large aspect ratio. Therefore, proper selection of the aspect ratio is needed for optimal heat transfer, depending on the amount of heat generated by the heat source.

UR - http://www.scopus.com/inward/record.url?scp=85030681654&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85030681654&partnerID=8YFLogxK

U2 - 10.1016/j.applthermaleng.2017.08.092

DO - 10.1016/j.applthermaleng.2017.08.092

M3 - Article

AN - SCOPUS:85030681654

VL - 127

SP - 1632

EP - 1641

JO - Applied Thermal Engineering

JF - Applied Thermal Engineering

SN - 1359-4311

ER -