An investigation of the efficiency of the receiver of a solar thermal cooker with thermal energy storage.

Abstract

A small scale solar concentrator cooker with a thermal energy storage system was designed, constructed and tested on the roof of the Physics building at UKZN, Westville campus (GPS co-ordinates: -29.817897, 30.942771) in Durban, South Africa. The system consisted of a 2.4 m diameter half-parabolic concentrating dish, a receiver, an automated solar tracking system, an oil heat transfer system and a pebble bed thermal storage. The effi ciencies of a at coil receiver and a cavity receiver were tested and compared, and the effi ciency of the thermal energy storage was investigated. The tests were conducted under similar conditions of solar insolation, wind speed and ambient temperature during the months of December 2012 and January 2013. The cavity receiver was found to have an effi ciency of 47 +- 12 %, which was more e fficient than the at coil receiver which had an e fficiency of 40 +- 11 %. The thermal energy storage was found to have an effi ciency of 87+- 3 %.