Hot air solar engine

Abstract

A hot air solar engine has two heat engines at opposing ends of a common piston assembly to provide alternate cooperative expansion and compression action. Each of the heat engines has a compressor and an expander wherein a single dual-diameter piston head serves as the piston portion of each. The hot air solar engine further includes a solar collector having positioning means for maintaining alignment with the sun's position. The solar collector has a paraboloid cylinder shaped reflector and a heat exchanger assembly disposed about the focal line of the reflector for receiving concentrated sunlight. The heat exchanger assembly includes first and second heat exchangers cooperating with the first and second heat engines. The heat exchangers are comprised of multiple parallel tubes each having a recuperator portion located within a recuperator chamber which receives heated air exhausted by the heat engines, and a collector portion located within a collector chamber equidistant from the focal line of the reflector which receives heat from the concentrated solar radiation. The recuperator chamber is contiguous to the collector chamber to increase solar efficiency, and the heat engines and heat exchanger assembly use environmental air as the working fluid allowing open system operation on an air-standard thermodynamic cycle. Fuel may be supplied to further heat the exhaust air through combustion as it is supplied to the recuperator chamber, thus permitting operation without sunlight.