Convective Heat Transfer Enhancement Using Alternating Magnetic Fields and Particle Laden Fluid Applied to the Microscale

摘要

This research investigated the miniaturization of a novel heat transfer enhancement technique. The technique, using alternating magnetic fields to influence a ferromagnetic particle laden fluid, was demonstrated to be effective on conventional scales using an oil based suspension, increasing the coefficient of heat transfer, h, by 260%. In order to determine the viability of this enhancement technique at smaller scales using a water based suspension, an experimental apparatus was designed to measure the coefficient of convective heat transfer in mini- and micro-scale flows. Water based suspensions of ferromagnetic particles were pumped through a 1.1 mm diameter heated tube. External alternating magnetic fields acted on the suspension, causing the particles to be attracted to and then released from the heat transfer surface. The efficacy of this enhancement technique was determined by comparing the heat transfer coefficients between enhanced and non-enhanced trials, while also considering the resulting increase in pressure loss. Dispersions of Fe and Fe304 particles were used during experimentation.