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.