Enhanced heat transfer in large-aperture PTSCs with semi-circular absorbers using multi-dipole magnetic field: A numerical study

This study investigates a large-aperture parabolic trough collector design featuring a half-cylindrical absorber tube, a planar radiation shield, and a glass cover. The components of the half-cylindrical absorber tube are a planar surface and a semi-circular surface. The multiple line dipoles magnetic field is created by electrical current-carrying wires. Therminol®VP-1/Fe3O4 fluid is employed as the magnetic fluid. Response Surface Methodology (RSM) is utilized to correlate the Nusselt number and Darcy friction factor. Correlations indicate that the Reynolds number has a nonlinear effect on the friction factor. However, the magnetic flux density has a nonlinear effect on the Nusselt number. At Re = 16000, the multi-dipole magnetic field (B = 90 G, ϕ = 0.04) leads to the Nusselt number ratio, performance factor, Darcy friction factor ratio, and dimensionless maximum temperature of 2.14, 0.81, 2.64, and 1.49, respectively. While the nanofluid (ϕ = 0.04, B = 0) has a weaker performance, resulting in the corresponding values of 1.88, 0.78, 2.4, and 1.55. Also, the increase in magnetic flux density leads to an increase in the Nusselt number, Darcy friction factor, and performance factor. The non-uniform magnetic field disrupts the boundary layer, induces mixing within the ferrofluid, and elevates turbulent kinetic energy.