Design and thermal analysis of nanofluid-based compound parabolic concentrator

• Published in: Renewable energy 2022-02, Vol.185, p.348-362
• Main Authors: Bhalla, Vishal, Khullar, Vikrant, Parupudi, Ranga Vihari
• Format: Article
• Language: English
• Subjects: Compound parabolic concentrator; Exergy efficiency; Nanofluid; Nanoparticles; Thermal efficiency
• ISSN: 0960-1481; 1879-0682
• DOI: 10.1016/j.renene.2021.12.064

Given the enormous demand for intermediate temperature applications such as heating, cooling, desalination and process industry; it is imperative to develop efficient low-cost solar thermal systems. In this direction, we propose a nanofluid based volumetrically absorbing receiver housed in a novel asymmetric compound parabolic concentrator (NCPC). Herein, we synergize the benefits of volumetric absorption and non-imaging concentrators for enhancing the output temperatures without increasing the collector area. A comprehensive optical-thermal modeling framework has been developed to assess the performance of the proposed design. Detailed analysis reveals that proposed design maintains high optical efficiency for a much wider range of angle of incidence (acceptable values of AOI: 30° to +90°) as compared to the conventional CPC design (acceptable values of AOI: 20° to +20°). Furthermore, a detailed parametric analysis reveals that nanoparticle volume fraction is the most critical parameter that impact the performance characteristics. Also, there exist, optimum values of nanoparticles' volume fraction (0.7%, 0.07% and 0.05% for carbon, aluminum and silver nanoparticles respectively) at which the system performs most efficiently. Finally, NCPC has been found to possess 8% higher thermal efficiency as compared to a corresponding non-concentrating nanofluid based collector under similar operating conditions and for a given aperture area. [Display omitted]