Thermal and optical performance test results for compound parabolic concentrators (CPCs)

The primary objective of the present study was to evaluate the performance characteristics (thermal and optical) of a properly truncated CPC that could be used in two-stage solar thermal power generation systems. The CPCs selected for testing were the 5:1 cones with a 25° acceptance angle and an untruncated concentration ratio of 5.6×. Experiments were carried out at the Advanced Components Test Facility of the Georgia Tech Research Institute. Several cones of the same dimensions but with different shell materials, reflector surfaces, and employing various heat removal methods were tested. It has been demonstrated experimentally for the first time that the CPCs with high reflectivity surfaces can have optical efficiencies in the range of 90% and above. In order to verify these results, a computer ray-trace analysis was also performed. These tests have shown that passive cooling alone is adequate for small-scale, low-power systems.