Shape Comparison for Solar Thermal Parabolic Collector

The KU EcoHawks are a mechanical engineering, undergraduate, senior design group at the University of Kansas that focuses on projects emphasizing a sustainable approach to automobiles and energy infrastructure. Much of the EcoHawks construction work is completed at a barn on campus that does not currently contain a heating or air conditioning system. Due to the temperature extremes reached in Kansas during the summer and winter months, thermal comfort is problematic for students working within the barn. This past academic year, one design group implemented a heating system for the barn utilizing a solar thermal parabolic collector. During the design phase, research of the literature found relatively little information in regards to the optimized depth of the parabolic curve. As a result, a prototype solar thermal parabolic trough was built in order to test three different parabolic shapes with varied depths. Static testing of a 50-50 mix of ethylene glycol and water found that the parabolic shape with the smallest focal length had the greatest solar collection efficiency. From this assessment, a final parabolic trough design was created. The assumptions, testing procedure, and results of static testing for the optimum parabolic shape of a solar trough collector will be addressed herein.