A review of different working fluids used in the receiver tube of parabolic trough solar collector

Parabolic trough solar collectors (PTSCs) or parabolic trough collectors have caught the interest of scientists and renewable energy enthusiasts due to their wide range of operating temperatures between 100 and 700 °C and their potential for power production as well as industrial process heating. More PTSCs have been constructed than all other concentrated sun-producing apparatuses put together. One of the most important functional components of the PTSC is the space for heat collection, also known as the absorber tube and transporting fluids. To increase its thermal potential, numerous investigations on the fluids in the absorber tube flow have been conducted. Better fluid thermo-physical properties are required to improve heat transfer and the system's overall efficiency. Examining different heat transfer fluids (HTF) that have been used for PTSC absorber tube/receiver tube is the goal of the current review. The usage of novel HTFs like nanofluids is also investigated, along with conventional fluids like thermic fluid and water. Review of the performance of the PTSC with various fluids using experiments and numerical methods are presented.. There are many difficulties with once-through PTSCs since two-phase flow circumstances make them worse and can occasionally cause tube bending. Summarized comparisons of several studies looking at the stability, manufacturing methods, and effects of hybrid nanofluids on PTSC thermal properties are summarized. For HTF inside the absorber tube, hybrid nanofluids and nanofluids may be used to enhance the thermal and optical characteristics of PTSC. It also demonstrates that metal oxide hybrid nanofluids are discovered to be more successful and efficient in enhancing thermal conductivity causing heat transfer augmentation than oxide nanofluids. This research, in our opinion, will encourage scientists and manufacturers to choose appropriate working fluids for PTSC applications.