Heat transfer augmentation of a PTC with rotating absorber, utilizing nanofluid and porous lines

Static parabolic trough solar collectors (PTCs) suffer from the localized high surface temperature caused by the focused solar irradiation. Accordingly, the absorber tube of the PTC is assumed to be rotated around its axis via a certain rotational velocity. In the present paper, various nanoparticles such as Al2O3, CuO, and ZnO are studied and compared with each other; also, porous aluminum metal foam lines with three different Darcy numbers of 0.1, 0.01, and 0.001 are utilized. Via the assumption of having a laminar and steady-state flow, a 3D solution is presented. Parameters, including the effect of flow rate, different nanofluids, rotation, and the presence of porous lines on the thermal performance of a solar collector, have been investigated numerically. Results indicate that the utilization of porous lines inside a rotating absorber tube can be resulted in about 15% and 40% in low and mid-range Reynolds improvement in the nanofluid's thermal efficiency compared to the case of not using porous media. Besides, a remarkable 12 K enhancement is reported in the outlet temperature of the nanofluid once porous lines are used. In addition, it is shown that depending on the Darcy number and rotation frequency, the thermal efficiency of the PTC can be increased at least 2%, too.

Automated summary

This paper investigates the thermal performance of a solar collector using nanofluids and porous lines. The results show that the utilization of porous lines can improve the efficiency of the solar collector and significantly increase the outlet temperature of the nanofluid. Additionally, the thermal efficiency can be further enhanced depending on the rotation frequency.