Desenvolvimento de um coletor solar assistido por termossifões

Abstract

In Brazil, a significant part of the electricity consumed on residences is for water heating. Worried about electricity high costs, solar collectors have been more used for this purpose. They have been highlighted, because solar collectors may promote water heating through solar irradiation, which is power source available and renewable. The main kinds of solar collectors are the flat plate and the focus ones. Between them, there are the solar collectors assisted by thermosyphon (or by vacuum) which are more efficient. These solar collectors have been developed in some Asian countries, Canada, USA and Middle East, meanwhile Brazil they are starting its process. On this term paper, will be presented a development methodology and experimental tests of a solar collector assisted by thermosyphon. First of all, it is stated the building process and five thermosyphon tests. They were tested individually for some different potential, filling ratios and tilt angle to evaluate its thermal behavior. A simple mathematical model, based on the operation limits, was applied to help in the thermosyphon development. After the construction and qualification through thermosyphons experimental tests, they were attached on solar collector. In sequence, the solar collector assisted by five thermosyphons was developed and tested on the laboratory. These tests showed that the thermal efficiency the collector was 59 % in a tilt angle of 9°, 69 % in a tilt angle of 17° and, finally, when the tilt angle was 25°, the thermal efficiency was 74 %. These values demonstrate that the solar collector assisted by thermosyphon has a higher thermal efficiency to conventional flat-plate solar collector tested by Carvalho and Sionek .