Experimental study of a sand-air heat exchanger for use with a high-temperature solar gas turbine system

An experimental study of the heat transfer characteristics of the bulk flow of sand in a sand-air heat exchanger is conducted. The study is conducted in the context of the development of a high-temperature solar gas turbine (HTSGT) system. This system is being developed by King Saud University and the Georgia Institute of Technology with the aim of demonstrating the feasibility of using sand as the heat transfer and energy storage medium in central receiver systems. Experiments are conducted on silica sand and olivine sand, both of which are attractive options due to their wide availability. The apparatus includes a tube bank consisting of eight electrically heated tubes arranged in three rows in a staggered formation. Heat transfer coefficient results are reported for bare and finned tubes for sand feed velocities of 1-3 mm/s. They were found in the range of 80-160 W/m2 K. © 2012 American Society of Mechanical Engineers.