Abstract:
A computational approach is presented, which uses the finite volume (FV) method in the Computational Fluid Dynamics (CFD) solver
ANSYS Fluent to conduct the ray tracing required to quantify the optical performance of a line concentration Concentrated Solar
Power (CSP) receiver, as well as the conjugate heat transfer modelling required to estimate the thermal efficiency of such a receiver. A
Linear Fresnel Collector (LFC) implementation is used to illustrate the approach. It is shown that the Discrete Ordinates method can
provide an accurate solution to the Radiative Transfer Equation (RTE) if the shortcomings of its solution are resolved appropriately in
the FV CFD solver. The shortcomings are due to false scattering and the so-called ray effect inherent in the FV solution. The approach is
first evaluated for a 2-D test case involving oblique collimated radiation and then for a more complex 2-D LFC optical domain based on
the FRESDEMO project. For the latter, results are compared with and validated against those obtained with the Monte Carlo ray tracer,
SolTrace. The outcome of the FV ray tracing in the LFC optical domain is mapped as a non-uniform heat flux distribution in the 3-D
cavity receiver domain and this distribution is included in the FV conjugate heat transfer CFD model as a volumetric source. The result
of this latter model is the determination of the heat transferred to the heat transfer fluid running in the collector tubes, thereby providing
an estimation of the overall thermal efficiency. To evaluate the effectiveness of the phased approach in terms of accuracy and computational
cost, the novel 2-D:3-D phased approach is compared with results of a fully integrated, but expensive 3-D optical and thermal
model. It is shown that the less expensive model provides similar results and hence a large cost saving. The novel approach also provides
the benefit of working in one simulation environment, i.e. ANSYS Workbench, where optimisation studies can be carried out to maximise
the performance of linear CSP reflector layout and receiver configurations.