Modeling a solar pressurized volumetric receiver integrated in a parabolic dish: Off-design heat transfers, temperatures, and efficiencies
[EN]Concentrated solar power plants are commonly recognized as one of the most attractive options within carbonfree
power generation technologies because of their high efficiency and feasible hybridization and/or storage
implementation. In this work, a complete heat transfer analysis for an air volumetric receiver coupled to
a parabolic dish focused on distributed generation (in the range of kWe) is carried out. It includes most
relevant heat losses. Dish collector optical efficiency is computed by means of a ray-tracing software while
the thermal performance of the solar receiver is modeled under steady-state conditions using a comprehensive
set of equations with a clear physical origin and meaning. Detailed information on the temperatures and
heat transfers along the different inner and outer receiver zones are computed with a built from scratch inhouse
code programmed in Mathematica®. The model considers the main losses from convection, conduction
and radiation and through the surrounding insulator. The resulting thermal efficiency mainly depends on the
incoming solar irradiance at the glass window, the receiver geometry and the type of materials considered,
as well as on the ambient temperature. Explicit numerical results are given at two locations under different
meteorological conditions. Optical efficiencies reach values of about 84%. For irradiance values around 800–
900 W/m2, at the receiver outlet, air can reach temperatures of about 1200 K and receiver thermal efficiency
is over 80%. It is expected that this model (precise but not too expensive from the computational viewpoint)
could help to identify the main efficiency bottlenecks, paving the way for optimization when designing this
type of concentrated solar plants through further coupling with a power block, as Brayton or other cycles.
