Coupled optical-thermal modeling, design and experimental testing of a novel medium-temperature solar thermal collector with pentagon absorber

The simulation, prototyping and testing of novel medium-temperature solar collector is elaborated in this paper. First, selection of higher concentration reflector (1.4 x) with optimized absorber geometry (pentagon) is justifledfor medium temperature application (100-300 degrees C). Afterwards, the collector with 6 evacuated tubes, CPC reflector and manifold is designed and coupled optical-thermal simulation is studied using finite element method implemented in COMSOL Multiphysics in order to predict optical and thermal efficiency of the system before prototyping. Finally, the proposed medium-temperature collector is tested with selective-coated pentagon absorber in the real condition at University of California, Advanced solar technology institute. The experimental and numerical results underscore a close similarity which the optical efficiency of 64% and thermal efficiency of 50% at 200 degrees C are achieved both numerically and experimentally. At the end, the proposed collector is compared with all major commercial collector both in performance and cost. The levelized cost of heat for a single collector is calculated as 3.1 cents/kWh. This price is cheaper than all categories of solar collector (Evacuated flat plat, Evacuated Tube, Fresnel lenses and parabolic trough) for medium temperature application (200 degrees C). Also, LCOH of proposed collector indicates the potential for solar thermal collector to challenge natural gas as California's primary heat source in the near future.