Design and ray tracing of a compound parabolic collector with tubular receiver

Ray tracing for solar collectors shows the behavior of light rays which falls on collector surface and reflected to the receiver. Accordingly the solar collectors are designed or modified to enhance thermal performance. Compound parabolic collectors (CPC) are capable of collecting and reflecting a large amount of solar radiation towards the receiver with less tracking effort. With the help of ray tracing technique its performance can be increased by minimizing the optical losses. In this paper, the limiting diameter (LD) of the tubular receiver at the focus of CPC is determined by the geometrical method of ray tracing. The CPC is designed and ray tracing analyses were performed without receiver to differentiate the region of maximum collection and no collection of reflected rays. The region where not a single reflected ray enters from a CPC half follows an elliptical shape which is tangent internally to the LD of the receiver at the focus and its geometrical relation with the acceptance angle is presented. The geometrical relationship between LD and maximum diameter is also determined. The receiver height is obtained on the basis of receiver surface covered and collector surface utilized.