针对平面线聚焦菲涅尔太阳能聚光透镜在光线倾斜入射条件下的焦距变化问题,从菲涅尔透镜结构、材料折射率以及光线倾斜入射角对其焦距的影响出发,分析得出兼顾许用倾斜入射角范围大和焦距变化范围小的设计参数.进而示例设计宽度为200 mm、焦距为300 mm、材料折射率为1.5的平面线聚焦菲涅尔透镜,分析其焦距变化特性,并采用缩短接收面与菲涅尔透镜之间安装距离的方法,分析得到适用于该菲涅尔透镜的最佳接收器宽度和安装位置,使其许用光线倾斜入射角范围达到±40°以上,以此维持平面线聚焦菲涅尔太阳能聚光器的有效工作时间达到接近6 h.
STUDY ON VARIATION OF FOCAL LENGTH OF FLAT-PLATE LINEAR-FOCUSING FRESNEL LENS
The design parameters of a flat-plate linear-focusing Fresnel lens were analyzed based on the influences of its structure,material refractive index,and tilt incident angle of sunlight on focal length.The analysis aimed to achieve large allowable tilt incident angles and small focal length changing ranges.An example was designed with a width of 200 mm,focal length of 300 mm,and material refractive index of 1.5.The characteristics of the Fresnel lens'focal length variation were examined,and an optimal receiver width and mounting position suitable for the lens were determined by shortening the mounting distance between it and the receiving surface.With an allowable light tilt incident angle range reaching±40° or more,nearly six hours of daily effective working time can be maintained.
solar energyFresnel lenslinear focusingtilted incidencefocal length change
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