Optical Cascade Heat-Collection for Effective Solar Energy Gain

Optical cascade heat collection of solar energy has proved effective for gaining thermal energy in the medium temperature region (80∼150° C). The cascade system consists of two separate absorbers (one hot and the other warm) and an optical system including CPC’s and Fresnel lenses which concentrate the direct solar radiation on one of the two absorbers. The temperature of the heat transfer fluid can be increased effectively if the fluid flows into the warm absorber first and then flows into the hot absorber. This type of solar collector, having no mechanical tracking device, can theoretically collect heat at a higher temperature than usual flat-plate collectors.