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Title:
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Inventarisatie warmte-opslag-concepten
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Author(s):
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Published by:
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Publication date:
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ECN
Energy Efficiency in Industry
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1-12-1999
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ECN report number:
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Document type:
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ECN-I--99-016
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Other
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Number of pages:
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Full text:
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126
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Download PDF
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Abstract:
Heat storage can improve the exploitation of renewable energy in thebuilt environment. The storage of thermal energy can be subdivided in short
and long-term storage, in active and passive systems and in working
principles (sensible, latent and chemical heat). In this report an overview
of heat storage systems is presented. Usually, storage systems are insulated
tanks filled with water. Small tanks are used in combination with solar
collector systems and large tanks in greenhouses. For a better stratification
vertical systems are preferred to horizontal tanks. Disadvantages are the
heat loss and the requirement of a large temperature difference to unload the
system. Phase Change Materials (PCM) have a large storage capacity in a small
melting range. Examples are salt hydrates and paraffines. A great deal of
research has been carried out to improve the heat conduction and heat
transfer. To avoid oxidation of the salt and loss of material, some PCMs are
encapsulated. These macro-encapsulated PCMs can be used in water tanks or a
water bag to increase the storage density. For passive systems in buildings
it is also possible to use organic or micro-encapsulated PCM in building
materials like wallboard and plasters. These building materials are not
commercially available yet. Chemical reactions like hydratation make it
possible to store energy without loss of heat and to transform the heat to
another temperature level. ECN is carrying out investigations on the
Na2S.nH2O system in the SWEAT project. In many locations in the
Netherlands, energy is stored in aquifers for large scale cooling and heating
demand. It is also possible to use small size closed systems with horizontal
or vertical heat exchangers in the ground. They are mostly used as a source
for heat pumps. 66 refs.
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