Enhanced heat transfer performance in a parabolic trough solar collector: A CFD investigation of silver and copper nanofluids utilizing porous medium

A recent study was being conducted to offer a three-dimensional numerical inspection of the water–Ag/Cu nanofluids’ hydrothermal profitability within a parabolic-trough solar collector incorporating a porous medium. This study aims to improve the thermal efficiency of parabolic-trough solar collectors by integrating nanofluids and porous media into the receiver tube. The focus is on enhancing heat transfer to the working fluid for better performance. In our numerical simulation, the working fluid of water (or nanofluid) at 5 different mass flow rates of 20, 40, 60, 80, and 100 L/h and with a temperature of 20°C enters the receiving pipe of a parabolic-trough solar collector while the non-constant heat flux is set on it. Copper and silver nanoparticles in volume fractions of (0.1 to 0.5%) and Darcy numbers of 0.1, 0.01, and 0.001 are simulated in applied porous media. The results of the simulations revealed that the use of a porous medium with (rp = 1 and Da = 0.1) and also in mass flow rate of 20 L/h, our receiver pipe saw a 2204.8% increase in the Nusselt number and 687.8% pressure drop, and the PEC was equal to the number 11.3. In the following, we examined copper and silver nanoparticles in two cases of applying porosity and without applying porosity in the receiving tube in volume fractions of 0.1 to 0.5%. Due to the creation of a high-pressure drop by the porous medium, nanofluids showed higher numbers for the performance evaluation criterion than unity for the non-porous state. Silver nanoparticles in volume fraction of 0.5% (at r_p= 1 and Da = 0.1) showed an increase of 71.3% and 197.8%, respectively, for the Nusselt number and pressure drop. In the case of non-porous copper nanoparticles with a volume fraction of 0.5%, they showcased an uptick in 217.6% and 3.8% respectively for the Nusselt number and pressure drop.