Compound Parabolic Concentrator for Pentagon Shape Absorber
Abstract
The design and development of new medium-temperature solar thermal external compound parabolic concentrator (XCPC) is presented. A nonimaging reflector is paired with an evacuated tube absorber for efficient heat collection between 100-300 °C. Several absorber geometries are simulated, with the final selection of a modified pentagon absorber shape chosen for manufacturability. The modified absorber shape, gap loss, and truncated reflector result in a geometric efficiency of 93% compared to an ideal CPC. Several selective coatings are compared for down-selection, and a Mylar reflective film with ~89% reflectance is chosen for its low cost and durability. The final prototype has a 4.56 m2 aperture. Simulations predict an optical efficiency of 71% and thermal efficiency of 50% at 200 °C and experimental test results have confirmed an optical efficiency of 62% and a thermal efficiency near 50% at 200 °C. The stagnation temperature was measured at 333 °C. World-wide installations are presented.