Construction and concentrating performance of a critically truncated compound parabolic concentrator without light escape

Abstract

Conventional solar CPC (Compound Parabolic Concentrator, CPC) has a limited collection of solar radiation at the end of the concentrating surface, which is not conducive to its wide application. In the present research, a solar CT-CPC (Critically Truncated CPC, CT-CPC) without light escape is proposed and constructed for the vacuum tube absorber, and discusses its optical properties, which provides a choice for improving or reforming the existing CPC system. Based on the edge ray principle, the geometric model of the CT-CPC is designed by the dichotomy method, and the concentrating performance of the CT-CPC is verified by the adjustable laser experiment. The study found that the average optical efficiency of CT-CPC reaches 47.84% and is 7.2% higher than the traditional S-CPC (Standard CPC, S-CPC) without light escape at the same aperture, and the energy flux distribution on the absorber surface is also more uniform, which is beneficial to improving system efficiency. The effective working hours of CT-CPC is higher than the S-CPC in the whole year, and the average effective working hours is 8.8 h and 5.7 h, respectively. The total annual radiation collection of CT-CPC is 3397 MJ/m2, which is 11.2% higher than the S-CPC. Furthermore, the economic analysis shows that solar CT-CPC has significant advantages and more friendly engineering application potential.