ASTRI: Improving performance of high-temperature receivers
A receiver is the device at the optical focal region of a solar concentrator. The role of the receiver is to convert focussed solar radiation into thermal energy, which can be carried away by a heat carrier (gas, liquid, solid particles or a mixture of these) for storage or further energy conversion downstream. The receiver strongly affects the levelised cost of electricity (LCOE) from concentrating solar thermal plants in two main ways. Firstly, LCOE scales almost linearly with the thermal efficiency of the receiver, because a more efficient receiver allows a smaller total solar collector area and secondly, the operating temperature of the receiver affects the power cycle efficiency, with higher temperatures enabling more efficient power cycles. The ASTRI receiver performance project aims to develop new, receiver technologies that are both highly efficient and that operate at temperatures suited to higher-efficiency power cycles such as ultra-supercritical steam power cycles and sCO2 Brayton cycles.
An initial scoping phase (planned for Jul 2013–Apr 2014) of this project identified opportunities that progress the state-of-the-art and have the potential to lead to significant reduction in LCOE. An internal ASTRI report presents findings across a range of topics including a review of state-of-the-art in existing receiver technologies, both commercial and under development, and in fundamental, cross-cutting areas such as heat loss mitigation, high-temperature materials, heat carriers, and selective surfaces. Exergy analysis was used to assist with the assessment of receiver concepts for further research.
The upcoming implementation phase (Jun 2014–Dec 2016) will involve development of two promising high-efficiency receiver concepts, in parallel, through to proof-of-concept stage. There will be a tubular receiver concept and a particle receiver concept. ANU will lead the tubular receiver stream, which will initially focus on a receiver with a working fluid of liquid sodium, and will examine areas such as peak flux limits, material selection, corrosion mitigation, storage and power cycle system integration, materials handling and safety issues, as well as novel ideas to minimise thermal losses including quasi-cavity designs to improve light trapping and dual-zone receiver concepts. The particle receiver stream (led by University of Adelaide) will initially assess three different particle receiver concepts. ANU will have an active role particularly with radiation, thermochemical and thermomechanical modelling of the particles, including radiative transfer in the cavity field and coupling volumetric radiation to other phenomena.