Energy Exergy and Environmental analysis of Parabolic Trough Solar Collector using Alumina water nanofluid and Twisted Tape Insert

Abstract

The utilization of renewable energy sources for industrial process heating has gained significant attention in recent years due to the increasing need for sustainable and environmentally friendly solutions. Solar energy, being one of the most abundant and clean sources of renewable energy, has emerged as a promising option for meeting industrial process heating requirements. Among various solar thermal technologies, parabolic trough solar collectors (PTSC) have been widely employed for their efficient and cost-effective performance. The efficiency of parabolic trough solar collectors in process heating can be improved by applying modifications in design of PTSC, by using selective coatings on absorber tube surface, by using improved heat transfer fluids, by using inserts in the absorber tube, etc. The present study includes the use of nanofluids and twisted tape inserts in the PTSC to investigate its thermo-hydraulic performance. newlineInitially, the stable Al2O3-water nanofluid was synthesized using two-step technique. Cetyltrimethylammonium bromide (CTAB) cationic surfactant is employed to improve nanofluid stability. Nanoparticles were suspended in the base fluid having different volume fractions of 0.25%, 0.5%, 0.75%, and 1%. Magnetic stirring with simultaneous heating is employed to improve distribution of nanoparticles in the carrier fluid. To enhance long-term stability, bath sonication with simultaneous heating and probe sonication technique is used. X-ray diffraction (XRD) results of nanoparticles ensured the and#947;-Al2O3 molecular composition and Scanning Electron Microscopy (SEM) image showed particle shape and mean particle size. To measure the stability, synthesized sample is tested at various time intervals such as 1, 8, 15, and 30 days using various stability evaluation techniques such as visual inspection, UV-vis spectrometry, and Dynamic Light Scattering (DLS). The nanofluid without surfactant has shown poor stability after 15 days of synthesis of nanofluid. Nanofluid with surfactant has shown higher absor