Coupled optical and thermal analysis of large aperture parabolic trough solar collector

• Published in: International journal of energy research Vol. 45; no. 3; pp. 4630 - 4651
• Main Authors: Malan, Anish, K., Ravi Kumar
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Inc 10.03.2021
• Subjects: Absorbers; Analysis; Apertures; Capital costs; Computational fluid dynamics; Darkening; Deformation; Diameters; Displacement; Distribution; Flow rates; Fluctuations; Fluids; Flux; flux distribution; Heat transfer; large aperture; Limb darkening; limb darkening effect; Liquid sodium; Mass flow rate; parabolic trough; Performance enhancement; Power plants; receiver displacement; Sodium; Solar collectors; Temperature gradients; Thermal analysis
• ISSN: 0363-907X; 1099-114X
• DOI: 10.1002/er.6128

Summary Large‐aperture parabolic trough solar collector (PTSC) has the potential to improve the performance of the solar field and also to reduce the capital cost of the power plant. In the present study, coupled flux distribution and thermal analysis of large aperture PTSC are presented by incorporating the limb darkening effect. MATLAB tool is used to develop the in‐house model to obtain the circumferential flux distribution on the absorber surface. The analyses are performed for different Sun shape models, the number of rays, aperture, rim angle, slope error, and receiver displacement on the flux distribution. The flux distribution for large aperture PTSC such as 7, 8, 9, and 10 m has also been studied with an available absorber diameter of 70, 80, 90 and 110 mm. Better manufacturing standards need to be incorporated to improve the performance of the large aperture PTSC with available receiver sizes. There is no significant effect on the intercept factor for the upward and downward displacement of larger aperture PTSC receiver, but the downward displacement of the conventional PTSC receiver drastically decreases the intercept factor. Based on the flux distribution analysis, a collector geometry having an aperture of 9 m with an absorber diameter of 110 mm has been considered for the thermal analysis. The effect of variation of the mass flow rate, aperture, and various heat transfer fluids are studied on the PTSC thermal performance. Liquid sodium offers the least thermal gradient around the absorber circumference, which leads to less deformation of the receiver from the focal length. In this article coupled optical‐thermal analysis of large aperture PTSC is performed to improve the nonuniformity of the flux distribution and minimise the thermal gradient on the absorber circumference. The analysis is performed for the various aperture sizes such as 5.77, 7, 8, 9 and 10 m with commercially available absorber diameter, that is, 70, 80, 90 and 110 mm. Furthermore, the effect of receiver displacement from the focal plane is also performed.