Consistent heat transfer analysis for performance evaluation of multichannel solar absorbers

The numerical evaluation of solar absorber performance must be based on the coupling between solar flux modeling and heat transfer modeling. We have developed a ray-tracing method to model the solar flux distribution absorbed at SiSiC multichannel absorber surfaces under a solar furnace, and solved one-dimensional heat transfer governing equations that import the solar flux modeling results. By consistently dealing with changes in properties or dimensions of absorbers for the two modeling processes, we are able to evaluate absorber performance with the balance of radiation loss. It turns out that the diffuse irradiation assumption is applicable for performance evaluation on multichannel absorbers although it may differ from a real solar flux distribution. A sensitivity analysis demonstrates that the increase of absorptivity is most effective to performance enhancement because the increase of reflection loss dominates the decrease of emission loss. The proposed consistent approach provides a better understanding of heat transfer in volumetric solar absorbers and thus helps the improvement of their performance.

► We evaluate the performance of volumetric absorbers with a consistent approach.
► The consistent approach allows us to break down radiation losses.
► Absorber performance is most sensitive to the absorptivity.
► The diffuse irradiation assumption in solar flux modeling is applicable for the evaluation of absorber performance.