Microporous foam, magnetic nanoparticles, and revolutionary tubes: Sophisticated combination of three solar energy materials in flat plate solar collectors

A novel and cost-effective method is employed to obviate conventional shortages of plate solar collectors by utilizing revolutionary tubes, microporous metal foam, and nanoparticles. In the new design, a thin metal foam is attached inside the tubes as a porous fin to increase the heat transfer area near the surface. Then, as the nanofluid passes through the tube, the rotation of the tube circulates the nanofluid and pushes it toward the porous fin by centrifugal force. This combined technique improves both convection and conduction mechanisms in the tubes and causes more thermal energy storage. Besides, the proposed method requires less pumping power because centrifugal force supplies part of the momentum for transport in the porous fin. Results reveal that 50.68% of the lost energy is managed and restored using the new method in the collector. In other words, 413 W more energy storage is achieved by the equipped solar collector compared to the simple one. Also, energy and exergy efficiencies rise by 22.8% and 8.5% in the manipulated system. Results confirm that the consuming power for pumping the nanofluid and rotating the tubes can be supplied by the system itself.