Experimental Study of a Domestic Solar Heater With Iron Ore as the Absorber

Abstract

In Brazil's households, the use of electricity to heat water prevails, but its replacement by solar collectors can be justified due to the country's high level of solar radiation, average temperature and number of sunny days. A drawback preventing the broad spread of this technology its elevated inicial cost that, in spite of the short return on investment time, hinders its insertions on the population lower classes. Thereby, this study's goal is to search a cheaper alternative to one of the collector's most expensive component, by proposing the replacement of the aluminium sheets, used as absorber, by iron ore. This material was chosen due to its abundance in Minas Gerais, low cost and for being dark colored, ensuring high levels of absortance (0,4 < λ< 0,7 µm). A finely grained hematitic () ore was used to achieve an uniform compaction throughout its area, reducing this way, the thermal contact resistance between the absorber and the copper tubes. The collector was built and tested in similar conditions it would have faced during its lifespan, and the result shows that the maximum thermal efficiency was 58%.