Effect of oval rib parameters on heat transfer enhancement of TiO2/water nanofluid flow through parabolic trough collector

The parabolic trough solar collector (PTSC) is recognized as one of the most efficient devices for generating solar energy. However, it suffers from relatively low thermal efficiency, which can be enhanced through the utilization of innovative coolant nanofluids (NFs) and a reconfigured receiver tube. In this study, computational simulations are conducted to analyze the thermal and hydraulic performance of a PTSC equipped with an oval ribbed receiver tube using TiO2/water NF. Turbulent flow simulations are carried out for different values of parameters, including the relative major diameter ratio, relative minimum diameter ratio, relative spanwise hydraulic diameter ratio, and relative streamwise hydraulic diameter ratio of the oval ribbed receiver tube. The simulations are performed across a range of Reynolds numbers from 8000 to 24000. Various performance indicators, such as the Nusselt number and friction factor, are examined to evaluate the overall performance of the solar collector using the k-epsilon model in commercial ANSYS Fluent 19.3 software. The optimal combination of parameters for maximum performance in the modified PTSC's receiver tube include dmaj/ Dp = 0.295, dmin/ Dp = 0.171, GSpan/ Oh = 3.0, GStream/ Oh = 24.5 at Renum of 24000 with φTiO2 = 2.0%.