To beam or not to beam down

摘要

Concentrating solar thermal (CST) technologies can be employed for high-temperature applications such as electricity generation, industrial process heat and solar thermochemistry. There has been on-going interest in tower reflectors or beam-down systems without any commercial systems in operation yet. This paper reviews the geometry of beam-down central receiver tower systems along with the resultant receiver flux distributions to develop an understanding of the opportunities for beam-down systems. It includes a qualitative analysis in terms of the field, tower, secondary reflector and receiver, as well other CST beam-down systems. Although beam-down systems will have a lower optical efficiency than an equivalent tower system, there is also a trade-off between either power or energy collection and concentration, although there are design options to improve these. The application of beam-down systems may be suited to applications, such as solar thermochemistry, where the cost of the additional plant is warranted by the value of the products.