The fouling of alloy-800 heat exchange surfaces by magnetite particles

The deposition of magnetite particles from suspension in water at nominally 90 degrees C onto Alloy-800 surfaces has been studied by chemical and radiotracing techniques under various conditions of flow, chemistry and boiling heat transfer. The experiments indicated that, under non-boiling conditions, mechanisms based on diffusion and thermophoresis control deposition while removal is negligible. For sub-cooled boiling at a low rate, the frapping of particles by bubbles is important; at a high rate, deposition during microlayer evaporation dominates. Removal occurs during sub-cooled boiling and is nicely described by a mathematical model in which it proceeds concomitantly with deposition.