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

Abstract

The simulation, prototyping and testing of novel medium-temperature solar collector is elaborated in this paper. First, selection of higher concentration reflector (1.4×) with optimized absorber geometry (pentagon) is justifiedfor medium temperature application (100–300 °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 °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 °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.