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Study of non-isothermal liquid evaporation in synthetic micro-pore structures with hybrid lattice Boltzmann model

Published online by Cambridge University Press:  08 March 2019

Feifei Qin*
Affiliation:
Chair of Building Physics, Department of Mechanical and Process Engineering, ETH Zürich (Swiss Federal Institute of Technology in Zürich), Zürich 8093, Switzerland Laboratory of Multiscale Studies in Building Physics, Empa (Swiss Federal Laboratories for Materials Science and Technology), Dübendorf 8600, Switzerland
Luca Del Carro
Affiliation:
Smart System Integration, IBM Research – Zurich, Saumerstrasse 4, Rüschlikon 8803, Switzerland
Ali Mazloomi Moqaddam
Affiliation:
Laboratory of Multiscale Studies in Building Physics, Empa (Swiss Federal Laboratories for Materials Science and Technology), Dübendorf 8600, Switzerland
Qinjun Kang
Affiliation:
Earth and Environment Sciences Division (EES-16), Los Alamos National Laboratory (LANL), Los Alamos, NM 87545, USA
Thomas Brunschwiler
Affiliation:
Smart System Integration, IBM Research – Zurich, Saumerstrasse 4, Rüschlikon 8803, Switzerland
Dominique Derome
Affiliation:
Laboratory of Multiscale Studies in Building Physics, Empa (Swiss Federal Laboratories for Materials Science and Technology), Dübendorf 8600, Switzerland
Jan Carmeliet
Affiliation:
Chair of Building Physics, Department of Mechanical and Process Engineering, ETH Zürich (Swiss Federal Institute of Technology in Zürich), Zürich 8093, Switzerland
*
Email addresses for correspondence: fqin@ethz.ch, feifei.qin@empa.ch

Abstract

Non-isothermal liquid evaporation in micro-pore structures is studied experimentally and numerically using the lattice Boltzmann method. A hybrid thermal entropic multiple-relaxation-time multiphase lattice Boltzmann model (T-EMRT-MP LBM) is implemented and validated with experiments of droplet evaporation on a heated hydrophobic substrate. Then liquid evaporation is investigated in two specific pore structures, i.e. spiral-shaped and gradient-shaped micro-pillar cavities, referred to as SMS and GMS, respectively. In SMS, the liquid receding front follows the spiral pattern; while in GMS, the receding front moves layer by layer from the pillar rows with large pitch to the rows with small one. Both simulations agree well with experiments. Moreover, evaporative cooling effects in liquid and vapour are observed and explained with simulation results. Quantitatively, in both SMS and GMS, the change of liquid mass with time coincides with experimental measurements. The evaporation rate generally decreases slightly with time mainly because of the reduction of liquid–vapour interface. Isolated liquid films in SMS increase the evaporation rate temporarily resulting in local peaks in evaporation rate. Reynolds and capillary numbers show that the liquid internal flow is laminar and that the capillary forces are dominant resulting in menisci pinned to the pillars. Similar Péclet number is found in simulations and experiments, indicating a diffusive type of heat, liquid and vapour transport. Our numerical and experimental studies indicate a method for controlling liquid evaporation paths in micro-pore structures and maintaining high evaporation rate by specific geometry designs.

Information

Type
JFM Papers
Copyright
© 2019 Cambridge University Press 

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Qin et al. supplementary movie 1

Experiment of liquid evaporation in SMS

Download Qin et al. supplementary movie 1(Video)
Video 199.9 KB

Qin et al. supplementary movie 2

LBM simulation of liquid evaporation in SMS_2D_Density

Download Qin et al. supplementary movie 2(Video)
Video 776 KB

Qin et al. supplementary movie 3

LBM simulation of liquid evaporation in SMS_2D_Temperature

Download Qin et al. supplementary movie 3(Video)
Video 4.1 MB

Qin et al. supplementary movie 4

Experiment of liquid evaporation in GMS

Download Qin et al. supplementary movie 4(Video)
Video 317.8 KB

Qin et al. supplementary movie 5

LBM simulation of liquid evaporation in GMS_2D_Density

Download Qin et al. supplementary movie 5(Video)
Video 601.7 KB

Qin et al. supplementary movie 6

LBM simulation of liquid evaporation in GMS_2D_Temperature

Download Qin et al. supplementary movie 6(Video)
Video 2.8 MB

Qin et al. supplementary movie 7

LBM simulation of liquid evaporation in SMS_3D_Density

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Video 473.3 KB

Qin et al. supplementary movie 8

LBM simulation of liquid evaporation in SMS_3D_Temperature

Download Qin et al. supplementary movie 8(Video)
Video 1.4 MB