Investigation of heat transfer in the internal flow of ferrofluid under the effect of magnetic field

In this thesis, the laminar forced convective heat transfer performance of a water-based ferrofluid composed of Fe₃O₄ nanoparticles under the influence of a magnetic field is experimentally investigated in a circular cross-section pipe. Two novel systems are designed for the application of the magnetic field as, phase-shifted magnetic field and variable-direction magnetic field. The experiments were conducted under a magnetic field intensity of 700 G, at various Reynolds numbers (ranging from 400 to 1000) and nanoparticle volume fractions (0.5% and 1%). In the phase-shifted magnetic field application, the heat transfer performance is evaluated for specific magnetic field frequencies (0 Hz, 1 Hz, and 5 Hz) and phase angles (0°, 90°, and 180°). In the variable-direction magnetic field application, heat transfer performance are analyzed for six different magnet configurations (M1a, M1b, M1c, M2a, M2b, and M2c). The enhancements in heat transfer rates, along with the corresponding pressure drop values are analyzed using a Performance Evaluation Criterion (PEC). According to the findings, the highest enhancements in heat transfer were observed at a 1% nanoparticle concentration and low Reynolds numbers. The maximum thermal performance is achieved at a frequency of 1 Hz and a phase angle of 180° for the phase-shifted magnetic field and with the M2b configuration for the variable-direction magnetic field.