拉伸变焦线性菲涅尔聚光器集热特性研究

Study on Heat Collection Characteristics of Linear Fresnel Lens Solar Concentrator in Tensile Deformation Causing Zoom

轻薄、光学效率高的线性菲涅尔透镜有望被广泛应用于太阳能聚光领域。然而,线性菲涅尔透镜在光线倾斜入射时焦距会变短,导致其全天有效集热时间短、集热效率低,严重阻碍了其规模化应用进程。为此,本文提出一种由超弹性透明材料制作的拉伸变焦线性菲涅尔聚光器。当光线倾斜入射时,通过力学拉伸改变透镜的棱镜结构,以此调整棱镜对光线的偏折角度,实现变焦。通过力学和光学仿真,揭示了该菲涅尔透镜在拉伸变形中的聚光特性。实际制作了开口宽度为200 mm、焦距为360 mm的菲涅尔透镜,并对其进行了实验研究。结果表明,拉伸变焦策略可将线性菲涅尔聚光集热系统的有效工作时长提高2 h以上,其全天高效聚光集热时长达6.5 h,期间的平均集热效率约为0.6。

The linear Fresnel lens is expected to be widely used in solar concentration fields because of its high optical efficiency and lightweight.However,the focal length of a linear Fresnel lens will become shorter when light tilt incidence occurs,resulting in short daily working hours and low energy collection efficiency of the Fresnel lens,which hinders its large-scale applications.In this regard,this paper presents a linear Fresnel lens made of transparent elastic material,whose focal length can be adjusted by tensile deformation.During light tilt incidence,the shape of prisms of the Fresnel lens is changed by mechanical stretching to adjust the angle of refraction of light to compensate for the change in focal length.The mechanical and optical joint simulations are carried out to study the concentrating behavior of the linear Fresnel Lens during tensile deformation.An exemplary linear Fresnel lens with an aperture width of 200 mm and focal length of 360 mm was designed and experimental studied.The test results indicate that the method of tensile deformation causing zoom can effectively increase the daily working hours of the linear Fresnel lens by more than 2 h.Additionally,the all-day experimental results indicate that the effective daily working hours of the linear Fresnel lens is 6.5 h,during which the average heat collection efficiency exceeds 0.6.