Modeling and Prediction of Urea-Water-Solution Droplet Evaporation Behaviour Under a Convective Environment

The current study involves developing and validating a bi-component droplet evaporation model for the urea-water-solution (UWS) droplet under a high-temperature convective environment for the urea-SCR after-treatment system. The conventional single-component droplet evaporation model developed by Abramzon-Sirignano was modified to a multi-component droplet evaporation model to predict the vaporization rates of a single isolated bi-component UWS droplet in high-temperature convective conditions through an in-house code developed in MATLAB®. An Effective Diffusivity (ED) droplet liquid phase model was adopted to account for the transient and spatial variation of temperature and species inside the UWS droplet by numerically solving the one-dimensional discretized energy and species transport equations using a finite difference approach. Most of the UWS droplet evaporation studies are validated with experimental data from a non-convective environment. Our model is validated with the recently published experimental data on UWS droplet evaporation under high-temperature convective conditions, and the predictions are in line with the experimental data. The three droplet liquid phase models, Rapid mixing (RM), Diffusion limit (DL), and Effective diffusivity (ED) models, were compared under different convective ambient temperature conditions. The results of the effective diffusivity (ED) model are close to experimental results when compared to the rapid mixing (RM) and diffusion limit (DL) models.