Análise do efeito de alterações de parâmetros de projeto em coletores solares planos para aquecimento de água
Abstract
The objective of this work is to present the manufacturing parameters of the solar
collectors, subject to modification, resulting in improved performance. A discretization of the
components of the solar collector was made, identifying the points that could be improved, the
importance of each one and its influence on the operation of the collector as a whole. These
modifications were simulated by means of a mathematical model, namely: the position of the
absorber surface; The distance between the absorber surface and transparent cover; The
relationship between thickness and width of the absorber surface. The EES (Engineering
Equation Solver) software was used to perform the simulation. The model that was
implemented in the EES was a flat solar collector of 1.0 m². After the simulation was carried
out, three prototypes were built, one with characteristics common to the collectors available in
the market and called the Standard and two more manufactured with the proposed
modifications. All the models were sent to the Thermal Efficiency test in a laboratory accredited
by INMETRO. The results of the simulation indicated that the change in the position of the
absorber surface shows an increase of 0.11 m² in the absorber area of the collector; The
computational simulation indicated that the increase in the distance between the absorber
surface and the transparent cover in the collectors generated an increase in heat loss from the
top of the collector of 0.058 W / m²K; The change of the thickness and width of the absorber
surface generated a reduction in the efficiency of 94% in the standard collector to 90% in the
proposed prototype. The combination of the mounting position and the distance between the
absorber surface and the cover showed a 5% increase in the energy production of this collector.
For the results of the laboratory tests it was observed that the prototype with the modifications
in the thickness and width of the absorber surface showed a decrease in its performance and the
prototype with the combination of the mounting position with the distance between the absorber
surface did not show an improvement in its performance , Which was contrary to the
mathematical model and whose explanation is due to the uncertainty of ± 2.92% of the
production line of the company supplying the prototypes.