LAUSR

Abstract The thermal and thermodynamic performance of parabolic trough solar collector (PTC) could be enhanced by using nanofluids due to their enhanced thermophysical properties. In this work, numerical and experimental investigations were carried out to study the effect of suspended industrial-grade multi-walled carbon nanotubes (MWCNTs) in distilled water (DW) for low to medium temperature PTCs. Stable nanofluids were prepared at various volume concentration of 0.05%, 0.1%, and 0.3%. Moreover, a one-dimensional numerical model is developed to investigate the optical and thermo-hydraulic performance of the commercial IST-PTC at different locations in the United Arab Emirates (UAE). The results of simulations show that Abu Dhabi is the best location with the highest annual thermal efficiency of 49.52%. Also, the suspension of MWCNTs nanoparticles in water results in an improvement of Nusselt number by 12%, 16%, and 21% for nanoparticle concentrations of 0.05%, 0.1%, and 0.3%, respectively. The impact of inlet temperature and flow rate are also investigated, and a thermodynamic analysis is carried out to study the entropy generation. The use of nanofluid at low concentrations could enhance the thermo-hydraulic performance for flow rates lower than 0.2 L/s, while nanoparticles concentration should be increased at higher flow rates for better heat transfer.