A solar Stirling renewable energy power system for earth and space applications.

A SOLAR STIRLING RENEWABLE ENERGY POWER SYSTEM FOR EARTH AND SPACE APPLICATIONS. Nathan Tinker, Covenant Christian Academy, Huntsville, AL 35803.

Lightweight, reliable power system designs are needed for portable earth-based applications and future space missions. The purpose of this project was to investigate electrical power generation of a solar-powered Stirling engine fitted with lightweight thin-film and acrylic concentrators. The concentrators provide focused solar energy to heat the engine, and enable the system to be lightweight. The Stirling engine was adapted for generating electricity by installing a lightweight linear alternator. Different solar concentrators were tested to discover the effects of concentrator parameters on energy collected. Experiments were also performed with 15.24 cm diameter acrylic Fresnel lenses to determine the effect of lunar dust simulant on concentration performance. Full system tests in ambient sunlight were performed with the concentrators and the modified Stirling engine. The lightweight concentrators were effective for heating the Stirling engine. The best performing concentrators were the 46 cm acrylic Fresnel lens and thin-film parabolic reflector, having concentration ratios of 92 and 58, respectively. A 50 g/m2 layer of lunar dust simulant on a Fresnel lens caused an 83% loss of concentrated energy. System output voltage increased consistently with increasing engine operating temperature, magnetic field strength, and coil length. The results achieved in this project indicate that the solar Stirling system with Stirling engine and lightweight Fresnel lenses or thin-film concentrators shows considerable potential for earth applications and future lunar missions. However, further development is needed for lunar applications to prevent the accumulation of dust on the concentrator.