Concepção e avaliação de concentradores solares do tipo disco e lente de fresnel para dessalinização de água

Abstract

The Sun is the main source of energy on Earth. Its energy capacity can be considered inexhaustible, it does not produce waste and has an adaptive allocation. Also in abundance, salt water is available on the planet covering most of the Earth\'s surface. However, today, more than one billion people around the world do not have access to clean water. In this scenario, the production of drinking water by desalination of salt water becomes fundamental. Therefore, this study aimed to the use of solar energy to desalinate water through solar concentrators, the disc types (CSD) and Fresnel lens (CSLF). For this, a theoretical study considering geometrical optics concepts was implemented to investigate, among four surfaces, the best that concentrated the sun\'s rays. In the same way, a computer simulation enabled the analysis of a dynamic heating through fundamental equations of Transport Phenomena. Thus, two prototypes were constructed using: a satellite dish, a Fresnel lens for an overhead projector, a tripod with astrophotography purposes and a simplied distillation system. These devices were experimentally characterized and the production of distilled water was determined considering solutions with 0% to 4% of sea salt. Therefore, the productivity of solar concentrators were compared, and a factorial experiment determined mathematically, system optimization conditions. As a result, the parabolic surface was the one with the biggest factor interception was therefore chosen as the prototype model. The simulation of the heating dynamics were validated experimentally and the highest temperature reached was of 319 graus C with a heating ramp that reached 75.56 graus C.min -1. In the construction of the prototype, the dish was mirrored by a chroming process and both the evaporator and the condenser was modified during the testing to take the format adopted in the experiments. In terms of productivity, the best results were 4.95 kg.m -2.day -1 for the CSD and 5.40 kg.m -2.day -1 for CSLF. The mass loading was the most significant variable indicated by the design of experiments but was also in uenced by colligative properties of the water. Therefore, this equipment meets a local demand for water due to the fact desalinate and disinfect brackish and salt water being able to satisfy, every m2 captured from sun\'s rays, the thirst of at least two adults.