THEORETICAL AND EXPERIMENTAL EVALUATION OF CONCENTRATING SOLAR COLLECTORS USING THE QUASI DYNAMIC METHODOLOGY
DOI:
https://doi.org/10.59627/cbens.2014.2168Keywords:
Parabolic cylinder concentrators, quasi-dynamicAbstract
This work presents a study of case utilizing data obtained from tests performed in a solar concentrating through collector and had the main goals to evaluate the thermal efficiency, as well, as, other important parameters which allowed the characterization of the collector, such as, the determination of the incident angle modifier “IAM”, and the effective collector thermal capacity. The concentrator is the main component of a small solar facility, named “Solar Plant”, which is localized at the Campus II of CEFET-MG. In this work it was utilized a methodology denominated “quasi dynamic method” described in the Brazilian Standard ABNT NBR 15745-2 of 2009, which is based on the European Standard EN 12975 of 2006. The standards use the model proposed by (Peres, 1997apud Osório, 2011) and according Osório this method is very versatile. Further, the Standards established other tests beyond the more conventional steady state test, such as, the tests to determinate the IAM and the thermal capacity of the collectors (Fischer et all, 2006). The tests were conducted in the months of July and August of 2013 and the collected data were the collector flowrate, inlet and outlet temperatures of the working fluid though the collector beyond the solar radiation incident in the horizontal plane, as well as, in the aperture plane of the collector. A mathematical model named Multivariable Linear Regression “MLR” is recommended by the standards and was used in this work to determine the thermal efficiency, the IAM among others parameters for the collector characterization. This method, according Osório, allows speed up the process of testing collectors in an order of two, compared to the conventional steady steady state method. The mayor advantage of the quasi dynamic method is that it is more flexibility than the steady state regarding the restriction of data acquisition, allowing the variation of variables such as solar beam radiation and fluid temperatures during part of the tests. In this work it is also presented an option that allowed the separation of the angle of incidence for the beam radiation, that allowed to obtain the terms of the thermal efficiency and the parameter “ b0 ” part integrant of the IAM.
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References
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