定日镜场光学效率的计算模型

A Computational Model for the Optical Efficiency of the Heliostat

定日镜场可将太阳光反射汇聚到安装在镜场中的吸收塔集热器上从而实现能量转换,不同的定日镜场参数会影响定日镜场的光学效率.本文通过光线追踪法与坐标变换等建立了定日镜场的光学效率计算模型,具体地,首先建立大地坐标系、镜面坐标系和光锥坐标系,并给出入射光线、反射光线以及法向的向量表示;其次,建立3个坐标系之间的坐标变换,利用坐标变换矩阵和方程联立判断并计算阴影遮挡损失、余弦损失、集热器截断效率等;最后,根据镜面反射率、大气透射率建立了定日镜场每块镜面的光学效率计算模型.

The heliostat field serves to reflect sunlight onto the absorber collector positioned within the mirror field,facilitating energy conversion.Various parameters within the heliostat field play a pivotal role in influencing its optical efficiency.In this study,we formulate a model for calculating the optical efficiency of the heliostat field through the implementation of ray tracing methodology and coordinate transformation.To begin with,our approach involves the establishment of a geodetic coordinate system,mirror coordinate system,and light cone coordinate system.We further develop the mathematical model for incident and reflected light within these systems.Subsequently,we establish coordinate transformations among the mirror,earth,and light cone coordinate systems.Through the utilization of coordinate transformation matrices and equations,we assess and compute shading efficiency,cosine loss,and efficiency of truncation.Finally,the optical efficiency of each mirror within the heliostat field is determined based on mirror reflectivity and atmospheric transmittance.