Optical and thermal performance of a uniaxial bidirectional tracked linear-focusing Fresnel lens solar concentrator

The focal length of linear-focusing Fresnel lens changing with incident angle is unavoidable, which goes against high-efficient solar energy collection. This paper proposes a uniaxial bidirectional tracked linear-focusing Fresnel lens solar concentrator, which maintains the advantage of single-axis tracking and meanwhile adapts to the focal length change. The uniaxial bidirectional tracker allows the Fresnel lens to track the sun axially and slide up or down to compensate for the focal length change throughout a day timely. A specially designed cylindrical Fresnel lens, which is mass-produced, is taken for study. Optical simulations are conducted to illustrate the optical characteristics of the Fresnel lens. The results indicate that the concentrator can efficiently collect solar energy when the tilt incident angle is within 45°. Then, a theoretical analysis is conducted to evaluate the concentrator's annual effectiveness with different installation modes (Tacking latitude of N40° as an example). The results indicate that the effective working hours of the concentrator in the horizontal east-west position reaches 6.8 h. Remarkably, when the concentrator is set in the south-north orientation, the full daytime solar collection throughout the year can be achieved as its installation angle β reaches 20°. Ultimately, an experimental setup is developed, and the comparative experiments well demonstrate the effectiveness of the uniaxial bidirectional tracked linear-focusing Fresnel lens solar concentrator.