QUANTITATIVE CHARACTERIZATION OF ADVECTIVE LOSSES IN A FALLING PARTICLE RECEIVER

Abstract

Concentrating solar power receivers use a thermal medium for energy storage. For falling particle receivers, ceramic particles are used both as the thermal storage and transfer medium. Inside the receiver described here, a gravity-driven particle curtain is irradiated through an open cavity with about 1 MW/m 2 of concentrated sunlight provided by a heliostat field. While this design offers important advantages, including high storage temperatures, there are some challenges associated with the design, such as advective particle loss from the receiver aperture. During operation plumes of particles being expelled out of the receiver cavity can be observed, resulting in heat/mass losses and an overall decrease in efficiency. We developed a non-intrusive measurement system to estimate these advective losses from the cavity of the receiver. It is based on an application of Particle Image Velocimetry (PIV) techniques to sets of thermograms obtained from a high-speed infrared camera. Both laboratory scale and field scale tests were conducted to validate the measurement process, after which we used field data to estimate efficiency losses, which proved to be modest.