A research program is under way at the University of New Brunswick to improve our understanding of the particulate fouling of water-cooled heat exchangers and to develop methods of predicting fouling under a variety of operating conditions. The program, so far, has involved experimental studies of the transport and deposition of colloidal magnetite on an Alloy-800 tube under non-boiling (reported here) and sub-cooled boiling conditions.
Fluent, a commercial fluid-dynamic software package, is used to compute the thermalhydraulic properties of the flow in the test section, via a k-ε turbulent model. The experimental deposition velocities are very well predicted using a convection-diffusion equation including Brownian and turbulent diffusion (Eulerian model). A Lagrangian model, based on the resolution of the equation of momentum for a particle, is also used to characterize better the relative importance of thermophoresis, lift and Brownian motion on the transport of magnetite particles.