A combined experimental and computational study of the heat transfer characteristics of falling liquid-films
File(s)
Submitted version
Author(s)
Charogiannis, Alexandros
Denner, Fabian
van Wachem, Berend GM
Kaliadasis, Serafim
Markides, Christos N
Type
Conference Paper
Abstract
An optical technique that combines planar laser-induced fluorescence (PLIF), particle tracking velocimetry (PTV) and infrared thermography (IR) was applied for the investigation of the hydrodynamic and heat transfer characteristics of harmonically-excited liquid films falling under the action of gravity over an inclined, electrically heated glass-substrate. PLIF was used to recover film-height data, PTV to recover two-dimensional (2D) velocity-field data, and IR to recover the temperature of the gas-liquid interface. The experiments were complemented by direct numerical simulations (DNSs) that provide additional information on the liquid viscosity, temperature and velocity distributions between the flow inlet and the downstream location where the optical measurements were collected. By adoption of this synergistic approach we recover a wealth of information, including novel results on the spatiotemporal evolution of the interface topology, and the flow and temperature fields underneath the wavy interface. Based on this data we also deduce local and instantaneous heat transfer coefficients (HTCs), and focus our efforts towards the investigation of two HTC-enhancement mechanisms; the observation of "hot-spots" as precursors to the formation of thermal rivulets, which can result in local enhancements in excess of 50%, and the presence of large velocity components in the crossstream direction of the flow, which promote mixing and are shown to improve heat transfer by up to ~ 7% compared to flow regions of the same height.
Date Issued
2018-03-04
Date Acceptance
2018-03-01
Citation
Proceeding of 3rd Thermal and Fluids Engineering Conference (TFEC), 2018, pp.985-994
ISBN
978-1-56700-471-7
ISSN
2379-1748
Publisher
Begell House
Start Page
985
End Page
994
Journal / Book Title
Proceeding of 3rd Thermal and Fluids Engineering Conference (TFEC)
Volume
2018-March
Copyright Statement
© 2018 Begell House.
Source
3rd Thermal and Fluids Engineering Conference (TFEC)
Publication Status
Published
Start Date
2018-03-04
Finish Date
2018-03-07
Coverage Spatial
Fort Lauderdale, FL, USA