SUMMARY

In a proposed design for a concentrating solar power receiver, granular material falls through a target zone which is illuminated by a large field of heliostats. To increase the temperature rise of the granular material, the design proposes to increase the residence time of the particles in the receiver target by means of a series of wire mesh screens. The goal is to not only impede the path of any one particles by the series of obstacles, but to promote mixing of the particles, thereby heat transfer to particles that might not be directly in the path of the incident solar irradiation.

Full scale testing of this concept is not expected to begin for several years, while lab scale testing might not be able to fully resolve the effects of all parameters related to the characteristics of the particles and the mesh screens. Thus, it is desirable to develop and experimentally validate a numerical model to quantify these effects. To this end, this investigation has been proposed. A small test section has been developed that can measure qualitatively and quantitatively the flow of granular material through differing sized orifices and screens. These flow tests are compared against predictions of an Eularian-Eularian simulation using the commercial software ANSYS Fluent v15 using the same geometries and material properties as the test section. Preliminary simulations are in qualitative agreement with the experimental results, but further refinements can be made. Once these simulations are in close enough agreement, parametric studies will be performed to quantify the effects of various design parameters and particulate material properties on the predicted mass flux, and hence, the residence time within the receiver. The model will be expanded to include the effects of incident solar radiation on the particulate temperature distribution. The non-isothermal model predictions will be compared against data obtained using the Georgia Tech Solar Simulator.