Abstract:
Many studies have been published on the performance and optimisation of the Brayton cycle
and solar thermal Brayton cycle showing the potential, merits and challenges of this
technology. Solar thermal Brayton systems have potential to be used as power plants in
many sun-drenched countries. It can be very competitive in terms of efficiency, cost and
environmental impact. When designing a system such as a recuperative Brayton cycle there
is always a compromise between allowing effective heat transfer and keeping pressure
losses in components small. The high temperatures required in especially the receiver of the
system presents a challenge in terms of irreversibilities due to heat loss. In this paper, the
authors recommend the use of the total entropy generation minimisation method. This
method can be applied for the modelling of a system and can serve as validation when
compared with first-law modelling. The authors review various modelling perspectives
required to develop an objective function for solar thermal power optimisation, including
modelling of the sun as an exergy source, the Gouy-Stodola theorem and turbine modelling.
With recommendations, the authors of this paper wish to clarify and simplify the optimisation
and modelling of the solar thermal Brayton cycle for future work. The work is applicable to
solar thermal studies in general but focuses on the small-scale recuperated solar thermal
Brayton cycle.
