Influência do material, tipo de escoamento e proteção transparente sobre o desempenho do coletor de um aquecedor solar de baixo custo

Abstract

Modern civilization is characterized by a large and disorganized energy consumption. As the sun is a renewable energy source, clean and inexhaustible, the operation of its light and heat becomes one of the most promising energy alternatives. Recent studies have encouraged the domestic use of solar energy replacing the use of conventional energy. The industry of solar collectors has been improved, in order to get a lower heat loss and thus a better utilization of solar energy. The use of alternative materials for the construction of collecting plates has been widely researched. This study aims to evaluate and compare the performance of two Low Cost Solar Heaters (LCSH) using PVC and polypropylene as raw material of the collector plate. Assays were performed passive (natural circulation) and active (forced circulation by peristaltic pumps) and with some setup changes in the experimental unit. These tests were performed in the main period of sunshine of the day, with the temperature values obtained by a monitoring system and data acquisition in real time. The information obtained, together with the knowledge of the values of solar radiation provided by a meteorological research center, the National Institute of Meteorology (INMET Instituto Nacional de Meteorologia), allowed the calculation of the efficiency of the collectors, the latter being defined by the ratio of heat absorbed by the plates and radiation total incident on them. Analysis of maximum temperatures attained by the systems \'boiler+plate\', the temperature gradients achieved in each setting, as well as knowledge of time and temperature obtained in the simulation of baths that use water from the reservoir of each backup catcher, lead to conclusion that the use of collector PP, together with the simplest configuration studied (thermosyphon without protection cover), provides water at a temperature for domestic use. This configuration for the LCSH has the advantages, in addition to the affordability of the population that does not yet have this technology, ease of handling and a positive contribution to eco-efficiency and environmental conservation.