Ferromanganese smelters generate significant amounts of fumes containing saturated vapours of metals. These conditions favour the formation of metal oxide nanoparticles. The presence of these nanoparticles in furnace off-gas may significantly affect the heat and mass transfer to the extraction ducting. Understanding this phenomenon can improve the design of the gas cleaning equipment. In this work, a mathematical model has been developed to quantify the effect of the presence of metal oxide nanoparticles on the overall heat and mass transfer in the gas flow.

This model considers the full set of Navier–Stokes equations for continuum fluid flows as well as the population balance equation to describe the spatial-temporal evolution of the particle size distribution. The model is built in the open-source OpenFOAM environment. The extended quadrature method of moments (EQMOM) is used to solve the population balance equation.

The simulation results include the distributions of velocity, pressure, temperature, and species concentrations in a typical exhaust duct. The model predicts the evolution of the moments of the particle size distribution function in the computational domain. The effect of the particles on the radiative heat transfer to the ducting is quantified.

Both the average particle size and distribution deviation increase along the flow in the ducting and in time. The rate of deposition of nanoparticles on the duct walls can be derived to determine the thickness and effective thermal conductivity of the layer deposited.