Optical dual-optimization strategy for a solar collector integrated compound parabolic concentrator with large-gapped reflector and absorber

Compound parabolic concentrator with large reflector-absorber gaps has proved to be advantageous but still need to enhance optical performance. It suffers from local radiation leakage that cannot be mitigated by reflector geometry modifications alone. A dual-optimization strategy was presented, which includes employing a baffle of 13 % absorber area on the flat absorber, and adjusting tilt of reflector in different seasons. Photothermal conversion calculations and ray-tracing simulations using Chinese meteorological data were validated by optics experiments, and results show some quantitative rules. The small baffle resolves local leakage in the large-gapped structure, and increase diffuse and direct radiation collection by 6.94 % and 2.31 %, respectively. Though this increase in not remarkable, its synergy effect caused by combining with tilt angle adjustment by single-axis rotation can significantly improve the seasonal optical performance, with greatest benefits in annual collected radiation increase by 84.34 % in winter. A novel index, integrating radiative performance and space utilization efficiency, enables optimal tilt angle determination for different cities. The dual-optimization could achieve 2.4–2.9 times enhancement in the performance index for winter and 1.8–2.5 times for summer. This work provides efficient optimization methodology for a particular type of concentrators, offering practical guidance for solar collecting system design.