Fluidized Bed Selective Emitter System Driven By A Non-Premixed Burner

One of the key priorities in the development of Thermophotovoltaic power technology is a highly efficient heat‐source/emitter system that is robust and stable. This paper describes a tightly coupled burner/selective emitter combination that integrates two novel concepts that are now under development: A fluidized bed emitter that consists of hollow, submillimeter spheres as the sources of radiant energy and a non‐premixed, self regulating burner. The rationale behind the proposed system is to combine the unique intrinsic features of both concepts to provide the TPV community with an enabling technology. The fluidized bed provides excellent heat transfer, temperature uniformity, high radiant power density, reduced substrate and combustion background, robustness, thermal shock resistance, minimal contamination, and long operational life. The paper discusses a fluidized bed system that consists of selectively emitting, hollow Ho‐YAG spheres with 500 micron diameter and 10–100 micron shell thickness operating at 1500 K. Key issues related to heat transfer and radiation transport in the fluidized bed are analyzed. The collective emitter efficiency and power density of a fluidized bed are discussed. The non‐premixed burner achieves very high temperatures, has a low emission in toxic byproducts, provides self regulating stability, eliminates flashback hazards, and is operable with hydrogen. The paper concludes with a description of a complete fluidized bed TPV system including an elliptic/parabolic transfer optics and a photovoltaic cavity converter that boosts the flux density received by the photovoltaic cells.