Enhanced Heat Collection Element Performance Through Surface Geometry

Concentrated solar power produces electricity by using a mirror to focus sunlight on a fluid filled tube known as a heat collection element. The fluid inside the element is then used as a heat source for steam generation in a conventional steam turbine power plant. It is possible that adding microstructures to the surface of the conventionally smooth heat collection element could improve system efficiency, motivating the need for an improved understanding of the radiation characteristics of a microstructured surface. The goal of this work was to experimentally determine the impact of different microscale geometries on net radiative heat gain when angle of incidence was varied. Five test pieces, one with a smooth surface and four with microstructured surfaces were compared experimentally for a given infrared energy input and flow rate and five different angles of incidence. Over the entire range of angles the microstructured test pieces absorbed more energy than the smooth test piece.