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Title:
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Experimental evaluation of commercial heat exchangers for use as PCM thermal storage systems
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Author:
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Medrano Martorell, Marc; Yilmaz, M.O.; Nogués Aymamí, Miquel; Martorell, Ingrid; Roca Enrich, Joan; Cabeza, Luisa F.
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Notes:
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Phase change materials (PCM) possess a great capacity of accumulation of energy in their temperature of
fusion thanks to the latent heat. These materials are used in applications where it is necessary to store
energy due to the temporary phase shift between the offer and demand of thermal energy. Thus, possible
applications are the solar systems as well as the recovery of residual heat for its posterior use in other processes.
In spite of this great potential, the practical feasibility of latent heat storage with PCM is still limited,
mainly due to a rather low thermal conductivity. This low conductivity implies small heat transfer coefficients
and, consequently, thermal cycles are slow and not suitable for most of the potential applications.
This work investigates experimentally the heat transfer process during melting (charge) and solidification
(discharge) of five small heat exchangers working as latent heat thermal storage systems. Commercial
paraffin RT35 is used as PCM filling one side of the heat exchanger and water circulates through the other
side as heat transfer fluid. Average thermal power values are evaluated for various operating conditions and
compared among the heat exchangers studied. When the comparison is done for average power per unit
area and per average temperature gradient, results show that the double pipe heat exchanger with the
PCM embedded in a graphite matrix (DPHX-PCM matrix) is the one with higher values, in the range of
700–800 W/m2-K, which are one order of magnitude higher than the ones presented by the second best.
Onthe other hand, the compact heat exchanger (CompHX-PCM) is by large the one with the highest average
thermal power (above 1 kW), as it has the highest ratio of heat transfer area to external volume.
The work was partially funded with the Project ENE2005-08256-C02-01/ALT and the Project 2005-SGR-00324. |
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Subject(s):
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-PCM
-Heat exchangers
-Heat transfer enhancement |
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Rights:
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(c) Elsevier, 2009
info:eu-repo/semantics/restrictedAccess |
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Document type:
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article
publishedVersion |
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Published by:
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Elsevier
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Share:
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