Title: Numerical study on solidification process inside annulus in presence of natural convection

Authors: Mehmet Akif Ezan; Aytunç Erek; Ibrahim Dincer

Addresses: Department of Mechanical Engineering, Dokuz Eylul University, Izmir, Turkey ' Department of Mechanical Engineering, Dokuz Eylul University, Izmir, Turkey ' Faculty of Engineering and Applied Science, University of Ontario Institute of Technology (UOIT), 2000 Simcoe Street North, Oshawa, Ontario L1H 7K4, Canada

Abstract: In this study, solidification process of water around a circular tube is analysed with presence of natural convection and heat gain from surroundings. The present model is validated by comparing the numerical predictions with experimental data. Some considerably high agreements are achieved in terms of time-wise variations of interface positions and temperature values. After validating the numerical method, further analyses are conducted to examine the influence of initial temperature value of water on solidification process. Time-wise temperature, local Nusselt number and local entropy generation variations are presented together with the isotherms, streamlines, and entropy generation patterns. The results indicate that influences of the local entropy generation and natural convection become significant for the initial temperature that is higher than density inversion temperature of water. For the parameters studied, entropy generation as associated with heat transfer becomes a deterministic factor for all cases.

Keywords: solidification; natural convection; density inversion; water; local entropy generation; phase change; annulus; circular tubes; local Nusselt number; heat transfer; temperature.

DOI: 10.1504/IJEX.2013.055074

International Journal of Exergy, 2013 Vol.12 No.4, pp.423 - 450

Received: 02 Apr 2012
Accepted: 01 Jul 2012

Published online: 15 Jul 2013 *

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