Open AccessAn experimental study of freezing and melting of water inside spherical capsules used in thermal energy storage systems
Author(s) -
Reda I. Elghnam,
Ramdan A. Abdelaziz,
Mohamed H. Sakr,
Hany E. Abdelrhman
Publication year - 2011
Publication title -
ain shams engineering journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.505
H-Index - 46
eISSN - 2090-4495
pISSN - 2090-4479
DOI - 10.1016/j.asej.2011.10.004
Subject(s) - materials science , thermal energy storage , heat transfer fluid , heat transfer , volumetric flow rate , volume (thermodynamics) , ethylene glycol , thermodynamics , thermal , energy storage , volume fraction , mass transfer , composite material , chemical engineering , power (physics) , physics , engineering
This paper reports the results of an experimental study on the heat transfer during freezing (charging) and melting (discharging) of water inside a spherical capsule of the type often found in the beds of thermal (ice) storage systems used for the building air conditioning systems. Spherical capsules of different diameters and materials are tested. The aqueous solution of 35-wt% ethylene glycol is used as the heat transfer fluid (HTF). The major studied parameters are the size and material of the spherical capsule, the volume flow rate and temperature of the heat transfer fluid (HTF). The effects of these parameters on the time for complete charging/discharging, the solidified/melted mass fraction, the charging/discharging rate, the energy stored/regain, and the energy recovery ratio (ERR) are studied. The experimental results show that the energy recovery ratio is becoming better when using metallic capsules, increasing the capsule size and reducing the HTF volume flow rates
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