Effect of magnetic field on the thermal performance of a ferrofluid‐based solar flat plate collector

Abstract

In this paper, the effectiveness of ferrofluid as a working fluid for solar flat plate collectors (FPCs) is studied. A mini‐ferrofluid‐based solar FPC is designed and tested under laboratory conditions. The thermal performance of the designed solar FPC is evaluated under different conditions and it is observed that it provides higher efficiency for the case of ferrofluid in the presence of a magnetic field. The thermal efficiency is observed to increase by 54% for ferrofluid in presence of a magnetic field as compared to no magnetic field. The thermal efficiency is observed to increase further with the increase in the magnetic field. The increase in thermal efficiency is attributed to the combined effects of higher thermal conductivity and magnetohydrodynamics of ferrofluid, which result in higher convective heat transfer from the riser tube walls into ferrofluid. The higher heat transfer for ferrofluid with a magnetic field is established by calculating the Nusselt number numerically using COMSOL. Simulation results show an increase in Nusselt number for ferrofluid with magnetic field and hence higher thermal efficiency for the solar FPC. The designed FPC provides simple modifications to conventional FPCs to use ferrofluid with magnetic field for higher thermal efficiencies.