CFD modelling of CaCO3 crystallization fouling on heat transfer surfaces

Modelling of solid formation by heterogeneous reactions through a multicomponent transport model of diluted ionic species: Simulation of barite fouling in a geothermal heat exchanger

“…One of the first studies conducted with the development of CFD modelled fouling by calcium sulphate deposition as a fictitious crystal growth: the impact of the solid formation is not taken into account in the description of the liquid flow . This approach can be found in other works like those by Pääkkönen et al and Johnsen et al where the growth of the deposit does not affect the position of the interface, which is treated as fixed. A pseudo dynamic approach has been developed by Zhang et al to overcome this limitation.…”

“…Some models are developed by adding an empirical crystallization‐fouling model into a CFD description of heat and mass transfer . In addition to the kinetic law that is required, a diffusive term is included in the description of the boundary, but is redundant with the CFD description.…”

“…In addition to the kinetic law that is required, a diffusive term is included in the description of the boundary, but is redundant with the CFD description. Furthermore, no profit is made from the knowledge of the local value of concentration as the rate of crystallization is evaluated from a mean value . In many papers, the reaction is included as homogeneous with a volume term in the transport equations but is then traduced as a surface growth of the deposit .…”

“…The link between the two terms is unclear. In a general way, the models presented are not complete, with often only a partial description of the internal equations and boundary conditions not present, incomplete or not linked with the internal models . Moreover, the models found in the literature focus on only one reaction and the ionic species are treated as uncharged, ie, electro‐migration is neglected.…”

“…The majority of these models are based on the approach introduced by Kern and Seaton in 1959, describing the growth of the fouling layer as the difference between the deposition rate and the removal rate. The earlier development of CFD allowed a better description of the phenomenon, but as seen previously, the full potential of this tool is not exploited and empirical models of solid growth are still used . Barite deposition has also been investigated as a crystal production process in various applications such as a hollow fibre membrane contactor, a stirred tank, and a coaxial pipe mixer, but the models are not satisfactory as we saw previously.…”