Investigation on structural and optical characteristics for an improved compound parabolic concentrator based on cylindrical absorber

In order to achieve the separation of absorber and reflector for compound parabolic concentrator (CPC) and solve effectively the drawback of resulting gap loss, an attempt to improve the structure and optical properties of CPC with cylindrical absorber is presented. Herein, a mathematical model of profile curve for the improved CPC is firstly established according to differential geometry. The structure of the improved CPC is more compact because of its saw-tooth, and it is beneficial to economize on the material with a reduced height of 24.1%. The ray path in practical application for improved CPC is verified via home-built experimental platform with laser generator. Furthermore, the mathematical relationships of optical efficiencies versus projected incident angles are revealed via numerical fitting. The optical efficiency curve for improved CPC is smoother and the non-uniformity of local flux distribution on absorber tube is mitigated, which predicts that the energy output of improved CPC is more stable. Compared with common CPC, the improved CPC provides an enhancement of absorbed total solar energy, which is increased by 8.3%, 4.8%, 7.4% and 2.9% in spring, summer, autumn and winter, respectively. The meaningful research results are beneficial to the structure design and performance enhancement of CPC. (C) 2020 Elsevier Ltd. All rights reserved.