Investigation of energy storage in parabolic rotary trough solar collectors using various porous fins with magnetic nanoparticles

The present study investigates the performance of various porous fin materials (copper, aluminum, bronze, and steel) with different porosities in a parabolic rotary trough solar collector driven by magnetic nanofluid. The nanofluid circulates in the rotary pipe and flows into the attached inner porous fin by a centrifugal force. This design enhances the heat transfer while reducing the pressure drop in the parabolic trough solar collector compared to previous configurations. Based on the results, the copper foam has the best performance among the studied materials, and the role of porous material is more salient in the rotational state than in the stationary one. Moreover, the increment of porosity causes more energy storage in the solar collector, while an optimal value is obtained for the rotational speed. The findings show that the heat transfer rate and pressure drop increase 3.7 times and 2.6 times in the optimal state of using copper porous fin with 97 % porosity in the rotary pipe with 0.6 rad/s angular velocity, respectively. Also, the energetic and exergetic performance increases from 71.6 % to 87.2 % and from 24.2 % to 40.5 %, respectively, and more than half of the lost energy is restored in the manipulated system.