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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

A STUDY ON COMPARISON OF VOLUME AVERAGED AND PORE SCALE RESULTS OF SOLID/LIQUID PHASE CHANGE ASSISTED BY POROUS MEDIA

Get access (open in a dialog) DOI: 10.1615/IHTC16.hte.022702
pages 5243-5250

摘要

The problem of solid/liquid phase change in a cavity assisted by a closed cell porous medium is analyzed by two approaches as pore scale method and volume averaged method. Because of the closed cell structure, the volume averaged of velocity is zero and the continuity and momentum equations are eliminated for the volume averaged approach and heat conduction in the frame and phase change material (PCM) becomes the only mechanism of heat transfer. The porosity value is chosen small (i.e., 0.54) to observe the effect of high speed propagation of heat transfer in the frame on the accuracy of the volume averaged technique. The comparison is performed for two different values of cavity Rayleigh (102 and 105) and Stefan (0.3 and 0.6) numbers. For both approaches, the equations are presented in dimensionless form to find out the dimensionless governing parameters. A cell averaged method for pore scale results is used to compare the results between two approaches. A good agreement between the results of two approaches for the frame is observed while there are differences for the PCM results. Due to high speed propagation of heat by conduction mode in the solid phase (frame), melting occurs simultaneously in entire domain however the same behavior cannot be caught by volume averaged technique. Furthermore, it is shown that the assumption of local thermal equilibrium may not be valid for the present problem.