This study, conducted by Alexandre M.S. Costa of the State University of Maringá and published by the State University of Ponta Grossa in Brazil, analyzes the annual energy performance of a closed-loop hot water solar thermal system under various weather conditions in 6 Brazilian cities (Curitiba, São Paulo, Rio de Janeiro, Recife, Salvador and Brasília) using the -f chart method. This method is based on 2 different approaches. It calculates the fraction (f) of monthly heat load that comes from solar energy. The calculation model uses a series of equations which are explained in details in the document. The results of this analysis show important variations of solar radiation from one season to another; higher in the summer and lower in the winter. It was also noticed that in the spring and the fall, the latitude of the cities plays a big role in terms of solar radiation. Results also showed a 4% decrease in solar contribution due to heat losses from the storage tank.
Author: Alexandre M.S. Costa
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