Modeling CaCO3 crystallization fouling on a heat exchanger surface - Definition of fouling layer properties and model parameters

Crystallization fouling occurs when dissolved salts precipitate from an aqueous solution to the walls of process equipment. In the case of inversely soluble salts, like CaCO3, this may lead to crystal growth on heated surfaces. In this study, crystallization fouling of CaCO3 on a flat-plate heat exchanger surface is studied. The mass deposition rates are determined from the measurements of the fouling thermal resistance and the properties of the porous fouling layer. The uncertainty of the fouling layer properties and the mass depositions rate are quantified with a detailed uncertainty analysis, which shows that the proposed method and experimental analysis provide values that are reasonably defined and acceptable. The obtained mass deposition rates are used to determine the kinetic parameters of different fouling models using a regression analysis. The validation of the models against the experimental data shows that the closest correspondence between the experimental and modeled results occurs when the crystallization fouling is described by the surface integration model including the time scaling factor which depends on the flow velocity.