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{Voulgaropoulos:2021:10.1016/j.ijheatmasstransfer.2021.121803,
author = {Voulgaropoulos, V and Kadivar, M and Moghimi, MA and Maher, M and Alawadi, H and Matar, OK and Markides, CN},
doi = {10.1016/j.ijheatmasstransfer.2021.121803},
journal = {International Journal of Heat and Mass Transfer},
pages = {1--15},
title = {A combined experimental and computational study of phase-change dynamics and flow inside a sessile water droplet freezing due to interfacial heat transfer},
url = {http://dx.doi.org/10.1016/j.ijheatmasstransfer.2021.121803},
volume = {180},
year = {2021}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - This study experimentally and numerically investigates the freezing characteristics and fluid dynamics of millimetre-sized sessile water droplets submerged in silicone oil at sub-zero temperatures under free convection. Individual water droplets were cooled to sub-zero temperatures (260-270 K) via interfacial heat transfer between the two liquid phases, in an approach different to studies in the literature where the cooling is done either from the solid substrate or from a low-temperature gas phase (such as air) surrounding the droplets. Laser-induced fluorescence was employed to perform spatiotemporally-resolved measurements of the phase distribution (from which interface distributions, freezing fronts, and rates were extracted). The particle image velocimetry was used to generate information on the velocity fields inside the liquid droplets. The experimental data are complemented by computational fluid dynamics (CFD) simulations, which showed acceptable qualitative and quantitative agreement with the experimental results. The experimental and simulation results indicated that prior to the initiation of freezing, two counteracting recirculation zones are generated in the central plane of the droplets, one on either side of the centreline, leading to a net upward flow at the edges and a downward flow in the centre due to the natural convection driven by internal temperature gradients. The nucleation sites appear on the external regions of the recirculation structures (which are locations with higher shear). Once freezing starts, the natural circulation patterns are suppressed, and instead, a sole downwards flow dominates, which is the result of the freezing layer suppressing the water phase. CFD results demonstrated a relatively wide temperature and pressure distribution in the water droplet at the beginning of the freezing stage, which gradually diminishes as the freezing process proceeds. The effect of droplet size and oil temperature on the freezing rates were in
AU  - Voulgaropoulos,V
AU  - Kadivar,M
AU  - Moghimi,MA
AU  - Maher,M
AU  - Alawadi,H
AU  - Matar,OK
AU  - Markides,CN
DO  - 10.1016/j.ijheatmasstransfer.2021.121803
EP  - 15
PY  - 2021///
SN  - 0017-9310
SP  - 1
TI  - A combined experimental and computational study of phase-change dynamics and flow inside a sessile water droplet freezing due to interfacial heat transfer
T2  - International Journal of Heat and Mass Transfer
UR  - http://dx.doi.org/10.1016/j.ijheatmasstransfer.2021.121803
UR  - https://www.sciencedirect.com/science/article/pii/S001793102100908X?via%3Dihub
UR  - http://hdl.handle.net/10044/1/91200
VL  - 180
ER  -
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