Optical Analysis of an Air Heating Concentrator Using a 2D Ray Tracing Technique
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2. ENGINEERING AND TECHNOLOGY, 2.3 MECHANICAL ENGINEERING
Solar concentrators offer a reasonable alternative to flat-plate collectors for delivering hot air flows at higher temperatures. They are designed to receive solar radiation through an aperture area and direct it towards a smaller absorber area by employing a reflective material. The design and analysis of solar concentrators are mostly based on ray tracing techniques. The aim of this paper is to analyse the optical performance of an Asymmetric Compound Parabolic Concentrator (ACPC) collector with an Inverted Transpired Absorber (ITA) for air heating. It accepts direct solar radiation during the summer period for up to 8 hours a day. The tool used for the optical modelling is the Ray Tracing technique, which consists of an algorithm developed in Matlab® that simulates solar rays entering this collector. The analysis considered the effect of the angle of the lower parabola axis, the glazing inclination and the tertiary section on the direct optical efficiency. Moreover, it also considered the energy distribution on the absorber surface under the effect of the tertiary section. The results show that the glazing optical losses can be reduced by inclining the glass from the vertical aperture as shown in Fig. 2, and that the reflection losses and the reflector material can be reduced by changing the lower parabola axis. The optical efficiency decreases as the tertiary section height increases however the energy distribution becomes more uniform.
Guerreiro, F. et al. (2018) Optical Analysis of an Air Heating Concentrator Using a 2D Ray Tracing Technique, International Conference on Energy, Environment and Economics, Edinburgh, 11-13 December 2017.