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|Title: ||Impact of different internal convection control strategies in a non-evacuated CPC collector performance|
|Authors: ||Horta, Pedro|
|Editors: ||Norton, Brian|
|Keywords: ||CPC collector|
|Issue Date: ||14-Feb-2012|
|Abstract: ||Over the last decade the technological advances observed in solar collector materials, namely better spectrally selective absorber coatings
and ultra clear glass covers, contribute to performance improvements and translate into higher operational temperature ranges with
higher efficiency values.
While the use of Evacuated Tube Collectors (ETCs) is becoming widespread in the thermal conversion of solar energy, non-evacuated
solar collectors still hold advantages at manufacturing, reliability and/or cost levels, making them interesting and competitive for a large
range of applications, in particularly, in temperature ranges up to 80 C. However, these advantages have not prevented the major drawback
of these collectors when compared to ETCs: thermal losses due to internal convection which prevent their general use in the range of
operating temperatures up to 150 C.
Insulation, double glazing or selective coatings can be used in non-evacuated collectors to reduce heat losses. To prevent internal convection
losses in these solar collectors, different control strategies have been studied, such as the adoption of different inert gases within
the collector cavity, physical barriers reducing air flow velocities over the absorber or cover surfaces or the use of concentration.
In the present article, an assessment of adopting such internal convection control strategies in a CPC collector is presented. Each of
the presented strategies is assessed in terms of the resulting collector optical and thermal characterization parameters and yearly collector
yield. For this purpose, an integrated tool allowing the design, optical and thermal characterization of CPC collectors was developed.|
|Appears in Collections:||CI-ER - Publicações - Artigos em Revistas Internacionais Com Arbitragem Científica|
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