Affiliation:
1. ENEA—Italian National Agency for New Technologies, Energy and Sustainable Economic Development, via Anguillarese 301, Roma 00123, Italy
2. ENEA—Italian National Agency for New Technologies, Energy and Sustainable Economic Development, via Anguillarese 3, Roma 00123, Italy
Abstract
Abstract
A linear receiver able to achieve temperatures up to 800 °C is presented. The high-temperature resistance is achieved by avoiding critical aspects (vacuum, glass-metal joints, surface films) that limit the temperature in usual receivers; the thermal insulation is obtained by enclosing the receiver tube in an elliptic reflecting cavity. The tube is placed near a focus of the cavity, and the primary collector concentrates the radiation on the other focus, where the cavity has a small opening: the ellipse reflects the radiation toward the tube and largely contains the reflected radiation and thermal emission, thus acting both as a secondary reflector and as a cavity receiver. Optical and thermal simulations show that temperatures up to 800 °C can be achieved, with optical efficiency above 70% and thermal efficiency in the range 45–85% for temperatures in the range 500–800 °C; the local overall efficiency ranges from about 40% to 66%, depending on the receiver tube emissivity and fluid temperature. In this way, the field of applicability of the linear collector technology can be significantly extended to include a vast amount of processes such as thermochemical cycles for hydrogen production, and solar fuel production processes, which require temperatures above 700 °C.
Subject
Energy Engineering and Power Technology,Renewable Energy, Sustainability and the Environment