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Heat and Mass Transfer

, Volume 55, Issue 11, pp 3359–3368 | Cite as

Enhanced dehumidification via hybrid hydrophilic/hydrophobic morphology having wedge gradient and drainage channels

  • Kai-Shing Yang
  • Yu-Yang Huang
  • Yao-Hsien Liu
  • Shih-Kuo Wu
  • Chi-Chuan WangEmail author
Technical Note
  • 101 Downloads

Abstract

Heat transfer performance under dehumidifying conditions for hydrophilic, and hybrid surfaces (hydrophilic/hydrophobic) within ambient are reported. The hybrid surface features star-shape morphology that contains hydrophilic interior inside star-shape while maintains a hydrophobic nature in the exterior of the star-shape. The star-shape offers comparatively good collecting capability of water condensate for its wedge gradient can effectively manipulate the surface energy. The mobility of the condensate within the star-shape interior is improved, leading to enhanced condensation heat transfer performance of 3.7~11.4% when compared to the hydrophilic surface. However, the contact angle hysteresis of the star-shape surface also retains the condensate inside the star-shape interior to some extent. To tackle this problem, a drainage channel alongside the gravity direction is added to the star-shape surface (star_I), and it offers a much better condensate removal, thereby improving the dehumidifying heat transfer performance up to 15.3~30.4%.

Nomenclature

A

Surface area, (m2)

Cp

Heat capacity, (J/(kg·K))

F

Surface force, (N/m)

h

Heat transfer coefficient, (W/(m2·K))

k

Thermal conductivity, (W/(m·K))

L

Length, (m)

Mass flow rate, (kg/s)

Nu

Nusselt number (hL/k), dimensionless

Pr

Prandtl number (ν/α), dimensionless

Q

Heat transfer rate, (W)

R

Radius, (m)

Re

Reynolds number (UL/ν), dimensionless

RH

Relative humidity (%)

T

Temperature, (K)

U

Mainstream velocity, (m/s)

α

Thermal diffusivity, (m2/s)

γ

Surface tension, (N/m)

θ

Contact angle, (°)

ν

Dynamic viscosity, (m2/s)

ϕ

Azimuthal angle of droplet, (°)

Subscripts

A

Advancing

B

Back of the droplet

F

Front of the droplet

H

Hysteresis

i

Inlet

L

Plate length

o

Outlet

philic

Hydrophilic

phobic

Hydrophobic

R

Receding

S

Surface

v

Vapor

w

Water

wet-grad

Gradient of wettability

X

X-direction

Ambient

Notes

Acknowledgements

The authors are indebted to the financial support from the Bureau of Energy of the Ministry of Economic Affairs, Taiwan and grants from Ministry of science and technology, Taiwan under contracts 107-2622-E-009-002-CC2 and 107-2622-E-009 -011-CC2.

Compliance with ethical standards

Conflict of interest

The authors claim there is no conflict of interest in this manuscript.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Kai-Shing Yang
    • 1
  • Yu-Yang Huang
    • 2
  • Yao-Hsien Liu
    • 2
  • Shih-Kuo Wu
    • 1
  • Chi-Chuan Wang
    • 2
    Email author
  1. 1.Green Energy & Environment Research LaboratoriesIndustrial Technology Research InstituteZhudongTaiwan
  2. 2.Department of Mechanical EngineeringNational Chiao Tung UniversityHsinchuTaiwan

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