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

The deposition of magnetite particles from suspension in water at nominally 90°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 trapping of particles by bubbles is important; at a high rate, deposition during micro‐layer evaporation dominates. Removal occurs during sub‐cooled boiling and is nicely described by a mathematical model in which it proceeds concomitantly with deposition.