Pool boiling under the magnetic environment: experimental study on the role of magnetism in particulate fouling and bubbling of iron oxide/ethylene glycol nano-suspension

Abstract

A set of experiments were conducted in a high-fidelity test rig to develop a new understanding on the role of magnetic field on the particulate fouling of iron oxide/ethylene glycol nano-suspension under a high heat flux pool boiling regime. Nano-suspensions were prepared at mass concentrations 0.1 and 0.2% and the tests were conducted up to heat flux 900 kW/m². Influence of different operating parameters including heat flux, mass concentration of nanoparticles, the strength of magnetic field and bulk temperature on the pool boiling heat transfer coefficient (as an index for thermal performance) and particulate fouling resistance of the surface was experimentally investigated and discussed. Results showed that the presence of magnetic field lowers the fouling resistance and increases the heat transfer coefficient at any mass concentrations of test nanofluid. Likewise, an increase in the bulk temperature of nanofluid increased the heat transfer coefficient as well. For any mass concentrations, presence of the magnetic field suppressed the fouling rate. For all the experiments, the fouling thermal resistance reached the asymptotic point in which the fouling resistance remains constant. The value of the asymptotic point was increased with an increase in the mass concentration of nanofluid. Eventually, magnetic field was found to mitigate the fouling formation of nanoparticles at any heat fluxes, mass concentration and bulk temperature of nanofluids.