A model of wax deposit layer formation

•We model wax deposit layer formation.•We assume thermodynamic equilibrium between wax solids and a fluid.•We consider a growing porous layer with a variable porosity.•Two major model equations describe wax diffusion and deposit growth rate.•We numerically study model performance varying different parameters.

A model of wax deposit layer formation is developed. The model is based on a mathematical description of diffusion of wax molecules through a growing porous layer. The deposit layer porosity reduction is caused by the growth of wax crystals, composing porous medium, in a wax-saturated hydrocarbon fluid. The two major model equations are: (1) diffusion of wax molecules through a porous medium with varying porosity; and (2) deposit layer growth rate. The model takes into account a diffusivity reduction with a porosity decrease and a shear-removal effect. The model performance is illustrated by computations of the wax deposition in a laboratory Taylor–Couette device.