Heat transfer and exergy destruction analyses with ferrofluid in LS-3 solar collector under dipole magnetic field

The parabolic trough solar collector is one of the most advanced technologies for employing solar energy. In these collectors, parabolic mirrors concentrate the sun rays on the absorber tube. In this article, performance improvement of parabolic trough solar collector (LS-3 solar collector) is studied by means of multiple line dipoles magnetic field. The non-uniform magnetic field created is perpendicular to the direction of motion of the fluid. Ferrofluid is used as a working fluid as well as to improve heat transfer properties. Monte Carlo Ray Tracing (MCRT) is used to ascertain the heat flux on the receiver's absorber tube. The exergy destruction and entropy generation are calculated using the second law of thermodynamics, and convective heat transfer coefficient is obtained for evaluating the performance of solar collector. In case of using multiple line dipoles, heat transfer and exergy destruction will increase and decrease, respectively. By applying external force, a secondary flow is created in the cross section of the absorber tube. Moreover, if the Fe₃O₄ nanoparticles are added to Therminol® VP-1, it will result in reducing the exergy destruction and improving the heat transfer. Also, with increasing ferrofluid velocity, frictional entropy and thermal entropy increase and decrease, respectively.