ENTECH proposes an innovative solar concentrator applicable to both static and dynamic energy conversion systems. The novel concentrator is an ultralight inflatable Fresnel lens, which can be configured as either a point-focus dome lens or a line-focus cylindrical lens. The point-focus dome lens will provide excellent optical efficiency ( 90%) at high concentration ratios (500-2,000X) required for solar dynamic conversion systems (i.e., Brayton and Stirling cycle converters). The line-focus cylindrical lens will provide excellent optical efficiency ( 90%) at moderate concentration ratios (9-30X) required for advanced photovoltaic arrays. Both configurations will provide extremely low mass due to the inflatable self-supporting structural approach. Both configurations will provide a 300-fold advantage in shape error tolerance over reflective optical oncentrators due to the proposed symmetrical-refraction lens design. Under the proposed Phase I program, ENTECH will produce conceptual designs for both lens versions, estimate their mass properties, perform a micrometeoroid damage analysis, determine the best methods for manufacturing the lenses, define optical performance levels, fabricate proof-of-concept models of the line-focus lens, prepare plans for later phases, and document all key results. The result of this SBIR project is expected to be a new family of inflatable, refractive, solar concentrators for future space power applications.
Potential Commercial Applications:The two versions of the inflatable Fresnel lens solar concentrator will have different commercial applications. The large dome-shaped, point-focus lens will be used to concentrate sunlight into cavity thermal receivers of solar dynamic conversion systems (Stirling, Brayton, or Rankine cycles) for space power. The small cylindrical line-focus lens will be used to concentrate sunlight onto advanced photovoltaic cells (GaAs,GaInP/GaAs tandem, GaAs/GaSb tandem) in space solar arrays. The line-focus version will be a natural improvement over existing rigid lenses made by ENTECH for photovoltaic concentrator arrays (PASP+, SCARLET1, SCARLET2). The point-focus version will be ideally suited for the potentially more efficient, lighter weight, and lower cost thermodynamic energy conversion systems of the future. The point-focus concentrator will also be used in solar thermophotovoltaic converters and solar furnaces for space material processing.
