Heat Transfer Enhancement Using Ferromagnetic Particle Laden Fluid and Oscillating Magnetic Fields

A convective heat transfer enhancement technique and the experimental method used to quantify the improvement in heat transfer are introduced. The enhancement technique employs time varying magnetic fields produced in a pipe to cause the ferromagnetic particles of a particle laden fluid (mineral oil and iron filings) to be attracted to and released from the pipe wall. The magnetic field remains energized long enough to attract particles to the wall and allow the heat to be quickly transferred to the highly thermally conductive particles. The released particles utilize their large surface area when dispersed to efficiently transfer heat to the bulk fluid. The ferromagnetic particles act not only to advect heat into the bulk fluid, but they also disrupt the boundary layer, allowing cooler fluid to reach the high temperature pipe wall, increase thermal energy transfer directly to the fluid and contribute to the overall improvement in heat transfer rate. The experimental method utilized to quantify increased effectiveness of convective heat transfer uses an experimental apparatus designed to replicate an internally cooled fin. The pipe test section acts as an internally cooled fin whose surface temperature is measured with an IR camera. These temperature measurements are then utilized to calculate the convective heat transfer coefficient (h) of the fluid within the pipe. The enhancement technique demonstrated a 250% increases in heat transfer coefficient for the experimental parameters tested.