Worst-case losses from a cylindrical calorimeter for solar simulator calibration

Abstract

© 2015 Optical Society of America.High-flux solar simulators consist of lamps that mimic concentrated sunlight from a field of heliostats or parabolic dish. These installations are used to test promising solar-thermal technologies for commercial potential. Solar simulators can be calibrated with cylindrical calorimeters, devices that approximate black body absorbers. Calorimeter accuracy is crucial to solar simulator characterization and maintenance. To discover the worst-case performance of a cylindrical calorimeter during flux measurement Monte Carlo ray tracing was coupled to finite volume simulations. Results indicated that the calorimeter can exhibit an observer effect that distorts the solar simulator flux profile. Furthermore, the proposed design was sensitive to changes in calorimeter optical properties, changes that can result from oxidation and/or photobleaching over time. Design fidelity and robustness were substantially improved through the use of a beveled (conical) calorimeter aperture.