Modeling of CaSO4 crystallization fouling of finned tubes during nucleate pool boiling

Abstract

The thermal superiority of nucleate boiling over convective heat transfer can greatly be compromised if crystallization fouling occurs on heat transfer surfaces for aqueous solutions with inverse solubility. The change of surface structure, such as finned tubes, though, is shown to have profoundly retarded the deposition process. There is not, nonetheless, a sound model in the open literature to predict fouling of structured surfaces, i.e. finned tubes. The present study proposes a new phenomenological model for finned tubes during nucleate pool boiling at different heat fluxes where CaSO4 solution was used as foulant. The proposed model can predict the supersaturation in the microlayer beneath the bubbles, which are formed on the surface during nucleate pool boiling, as a function of geometry. The fouling resistances predicted from the model were compared with the experimental data, and good quantitative/qualitative agreement was achieved.