Thermo-hydraulic performance of a parabolic trough solar collector filled with three different waste materials

This study presents the experimental investigation of the performance enhancement of a parabolic trough solar collcector (PTC) utilising air as the working fluid and various metallic waste materials as absorber fillers. The experiments have been carried out according to the ISO 9806:2017 norm under clear sky conditions for several days. The application of wire mesh, metal chips and bearing balls as the absorber filling has led to the increase in the performance of PTC and higher outlet temperatures compared to the smooth pipe as a receiver: 282 % (117.6 °C), 250 % (103.1 °C) and 335 % (128.3 °C) respectively. A decrease in PTC performance due to pressure drop was observed. The maximum drop for wire mesh, metal chips and bearing balls filling was: 9.7 %, 5.7 % and 5.7 % respectively. It has been shown that the use of metallic waste materials can significantly improve the thermal performance of PTC, but the rapidly increasing hydraulic resistance may limit their application for high flow rates. • PTC outlet air temperature increased by up to 76 % thanks to the use of metal inserts. • Waste materials as absorber filling caused a relative efficiency increase of max 335 %. • A decrease in PTC efficiency due to pressure drop of up to 9.7 % was observed.