Análise da variação dos parâmetros geométricos no desempenho de um refletor Fresnel Linear

Abstract

The objective of this work was to analyze the impact of the linear Fresnel reflector (LFR) parameters on its geometric efficiency and to define the width of the absorber according to the dispersion of the radiation reflected by the field of mirrors in the absorber input plane. The parameters analyzed were absorber height, mirror width, mirror spacing, radius of curvature for cylindrical curved mirrors and focal length for parabolic curved mirrors. The geometric efficiency was evaluated considering the energy in the form of solar radiation incident on the LFR during a day and the energy that effectively reached the absorber. In this analysis we also evaluated the losses present in the process, such as shading of the mirrors by the absorber, loss of radiation between mirrors, blocking between mirrors, cosine effect and losses by shading between mirrors. The methodology used for the analysis was the ray tracing, executed with a code developed in MATLAB. It was possible to conclude that the use of curved mirrors, with small rim angles, enables greater efficiency than with flat mirrors. The shape of the curvature, whether parabolic or cylindrical, did not affect the efficiency of the LFR. Spacing between mirrors must be the minimum that allows the movement of mirrors without the risk of interference. The increased height of the absorber also caused an improvement in the efficiency of the LFR. The parameters that minimize the width of the absorber, which was very important to minimize the losses by shading of the absorber on the field of mirrors, were determined. Other losses were also determined for each set of analyzed parameters. The results obtained can provide information for new projects.