Análise numérica do comportamento da temperatura ao longo de um coletor solar e reservatório de água

Abstract

This work was structured in order to describe the thermal behavior of a solar collector for water heating, built from recyclable materials (PET bottles and Tetrapak packaging). The main rationale for this study is the gradual importance of developing technologies associated with the use of renewable energy sources. Using Computational Fluid Dynamics resources (CFD), the main heat transfer mechanisms responsible for heating the water have been identified. A description of the dynamics of the heating hot water tank was also performed. A preliminary study indicated the slight influence the thermal conductivity of the Tetrapak packaging plays in heating the water, due to the small thickness of these surfaces. Results slave shown that the water outlet temperature is strongly influenced by the air temperature inside the PET bottles. These results were used to direct subsequent simulations. The computer simulation performed on the collector showed that the highest temperature of the fluid occurs in the output of the tubes, which is the mechanism that generates the thrust responsible for disposal. It also appeared that the outlet temperature of the water is proportional to the number of used tubes. Specifically, we arrived to a eleven percent increase in the temperature to increase in the number of tubes tenfold, given the fact that the mass flow rate was kept constant. Finally, analysis of the thermal reservoir, in transient, indicating a tendency towards thermal stratification in which the hot fluid is located at the top and bottom of the cold fluid in the equipment.