Concentrating Collectors

High-temperature collectors using optical concentration and tracking, are described in this chapter. The determination and optimization of the optical performance of line-focusing and point-focusing technologies is key for reaching high temperatures. We classify therefore the collectors by their optical concentrator principle. Although also the selected heat transfer fluid has an impact on the temperature level which can be achieved, due to fluid stability and receiver material durability issues, this aspect is only treated in Chap. 10 on high temperature collector systems and fields. Here, the focus is on the main components and designs of individual collectors. As solar radiation is transformed into heat in the receiver, the design of this element is mainly responsible for minimizing the thermal losses. However, thermal losses play a minor role, the higher the optical concentration. We present receiver designs, determine the selection of materials, and define the performance. Finally, some line- and point-focusing collector types are compared with respect to their optical performance characteristics.