Imperial College London
Alternate

ProfessorChristosMarkides

Faculty of Engineering, Department of Chemical Engineering

Professor of Clean Energy Technologies
 
 
 
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Contact

 

+44 (0)20 7594 1601c.markides Website

 
 
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Location

 

404ACE ExtensionSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Charogiannis:2019:10.1016/j.expthermflusci.2018.11.001,
author = {Charogiannis, A and Markides, CN},
doi = {10.1016/j.expthermflusci.2018.11.001},
journal = {Experimental Thermal and Fluid Science},
pages = {169--191},
title = {Spatiotemporally resolved heat transfer measurements in falling liquid-films by simultaneous application of planar laser-induced fluorescence (PLIF), particle tracking velocimetry (PTV) and infrared (IR) thermography},
url = {http://dx.doi.org/10.1016/j.expthermflusci.2018.11.001},
volume = {107},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We present an optical technique that combines simultaneous planar laser-induced fluorescence (PLIF), particle tracking velocimetry (PTV) and infrared (IR) thermography for the space-and time-resolved measurement of the film-height, 2-D velocity and 2-D free-surface temperature in liquid films falling over an inclined, resistively-heated glass substrate. Using this information and knowledge of the wall temperature, local and instantaneous heat-transfer coefficients (HTCs) and Nusselt numbers, Nu, are also recovered along the waves of liquid films with Kapitza number, , and Prandtl number, . By employing this technique, falling-film flows are investigated with Reynolds numbers in the range , wave frequencies set to , 12 and 17 Hz, and a wall heat flux set to Wcm−2. Complementary data are also collected in equivalent (i.e., for the same mean-flow Re) flows with Wcm−2. Quality assurance experiments are performed that reveal deviations of up to 2-3% between PLIF/PTV-derived film heights, interfacial/bulk velocities and flow rates, and both analytical predictions and direct measurements of flat films over a range of conditions, while IR-based temperature measurements fall within 1 °C of thermocouple measurements. Highly localized film height, velocity, flow-rate and interface-temperature data are generated along the examined wave topologies by phase/wave locked averaging. The application of a heat flux (Wcm−2) results in a pronounced “thinning” of the investigated films (by 18%, on average), while the mean bulk velocities compensate by increasing by a similar extent to conserve the imposed flow rate. The axial-velocity profiles that are obtained in the heated cases are parabolic but “fuller” compared to equivalent isothermal flows, excluding any wave-regions where the interface slopes are high. As the Re is reduced, the heating applied at the wall penetrates through the film, resulting in a pronounced coupling between th
AU  - Charogiannis,A
AU  - Markides,CN
DO  - 10.1016/j.expthermflusci.2018.11.001
EP  - 191
PY  - 2019///
SN  - 0894-1777
SP  - 169
TI  - Spatiotemporally resolved heat transfer measurements in falling liquid-films by simultaneous application of planar laser-induced fluorescence (PLIF), particle tracking velocimetry (PTV) and infrared (IR) thermography
T2  - Experimental Thermal and Fluid Science
UR  - http://dx.doi.org/10.1016/j.expthermflusci.2018.11.001
UR  - http://hdl.handle.net/10044/1/64875
VL  - 107
ER  -
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