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Influence of the absorber tubes configuration on the performance of low cost solar water heating systems

Barbosa, Eloiny Guimarães, Araujo, Marcos Eduardo Viana de, Moraes, Maria Joselma de, Martins, Marcio Arêdes, Alves, Beethoven Gabriel Xavier, Barbosa, Elisa Guimarães
Journal of cleaner production 2019 v.222 pp. 22-28
bottles, developing countries, heat, insulating materials, packaging, poly(vinyl chloride), polyethylene, solar collectors, solar heaters, temperature
Flat plate solar collectors have been widely used in low temperature thermal applications (<80 °C), for example, domestic use. However, in developing countries, the high cost of equipment hinders its dissemination, especially among low-income consumers. In this study, two configurations of low cost solar heaters (LCSH) were constructed and thermally evaluated. The systems were composed of flat plate solar collectors and their heat reservoirs, consisting of three alternative materials: PVC tubes, PET bottles and long life packaging. In the first configuration (LCSHS), the tubes of the absorber plate were connected in series whereas in the second configuration (LCSHP), the tubes were connected in parallel. The heat reservoirs of both systems are made of HDPE, coated with EPS for insulation. The temperature values were measured in three sections in the heat reservoirs: top section, intermediary section and bottom section. The heat loss in the reservoirs and the thermal efficiency of the systems were evaluated. LCSHP presented superior performance when compared to LCSHS. The maximum temperatures and efficiencies reached were 49.7 °C and 40.9% for LCSHP and 47.8 °C and 37.8% for LCSHS. Both systems performed similarly to the conventional systems. Therefore, they are recommended for low-income consumers who have no access to conventional energy sources. The cost of the proposed systems is about 6 times lower than conventional systems.