Design and analysis of a novel 3-D elliptical hyperboloid static solar concentrator for process heat applications

Abstract

In the present thesis, performance characterisation of a novel non-imaging concentrator, a 3-D elliptical hyperboloid concentrator (EHC) for process heat applications (medium temperature) is investigated. In this investigation, optical and thermal characterisations are extensively carried out for the novel 3-D static concentrator. In the optical study, a 2-D ray tracing simulation was carried out in MATLAB® to predict the optical efficiency of the EHC. The 3-D ray tracing was also carried out in OptisTM software to obtain the optical efficiency. Detailed flux distributions on the receiver are also analysed. Ray tracing and flux distributions were investigated for different solar incidence angle by varying the system parameters such as concentrator height, receiver diameters and concentration ratio. A parametric analysis of four different system configurations, (I) Elliptical Hyperboloid Concentrator (EHC), (ii) Circular Hyperboloid Concentrator (CHC), (iii) Elliptical Parabolic Concentrator (ECPC) and (IV) Circular Parabolic Concentrator (CCPC) were performed. Based on the parametric analysis it was found that the EHC gives better optical performance compared to other configurations. It was found that the EHC gives better optical performance than others. It was also found that for a wide range of acceptance angles (±30) the optimised concentration ratio of 20× resulted in an optimised optical efficiency of 28%. For thermal performance, separate indoor and outdoor characterisations were conducted to predict the receiver stagnation and fluid temperatures. In the indoor test, the performances of three different hyperboloid solar concentrators (EHC1, EHC2 and CHC) were investigated. The outdoor performance test was also carried out for a scaled-up version of the developed prototype of the 3-D static elliptical hyperboloid concentrator system (EHC) of 20× concentration ratio. The tests were carried out at Chennai, INDIA to obtain the maximum stagnation temperature and daily performance of the EHC system. It was observed that a maximum temperature of 150°C is obtained as the stagnation temperature. In the daily performance test, the maximum fluid temperature of 90°C was observed. Thus, the developed 3-D static elliptical hyperboloid concentrator system can be effectively used for medium temperature applications.