aperture area has been installed at DLR inCologne (Figure 12) with financial support from the „Arbeitsgemeinschaft Solar“ of the
federal state Northrhine-Westfalia. The size of the field allows for realistic efficiency
measurements, which include e.g. soiling of the collector surface and blocking and shading of
structural elements. Inlet temperatures between 20°C and 200°C and mass flows up to 10 m³/h
are delivered by a balance of plant, using pressurized water as heat transfer medium. The
receiver is not evacuated and contains an absorber tube with black nickel selective coating. A
polymeric reflective film glued to an aluminum sheet concentrates the radiation.