Dibutyl phthalate nucleation

 

In order to validate the aerosol dynamics modeling in terms of aerosol formation through nucleation and subsequent condensational growth, we simulate the Laminar Flow Diffusion Chamber (LFDC) of Nguyen et al. (1987). In this setup, a saturated vapor is released in a pipe in which a low-Reynolds number flow transports the vapor towards a cooled zone. The cooling of the mixture leads to a supersaturation of the vapor that in turn leads to nucleation. With the sectional aerosol model we may capture the complete distribution of droplets. We compare against the experimental data of Nguyen et al. (1987) in terms of the formed droplet distribution. The conditions are such that at the inlet the temperature is 375.15 K and at the outlet 294.55 K. The configuration of the case available in the AeroSolved code repository in 'cases/validation/NguyenLFDC', is described in detail in the PhD thesis of Frederix (2016). The validation case can be executed by calling the following scripts for preparation, running and post-processing: prep.sh, run.sh (will take a long time) and post.sh. The post.sh script requires Python with Matplotlib to be installed, and creates plot.pdf (see below) that shows the generated sectional droplet number concentration (in terms of dN/dlog d) as a function of the droplet size, where N is the droplet number concetration and d is the droplet diameter. The experimental data of Nguyen et al. (1987) are also shown. Note that the final distribution, which is created due to nucleation and condensation is quite close to the measured one, but shows a small underestimation of the mean droplet size. Knowing the large sensitivity of these simulations to the chosen parameters (e.g., diffusion, surface tension and vapor pressure) along with uncertainties concerning the application of the classical nucleation theory, this result can be considered as reasonable, within the context of aerosol nucleation and condensation modeling.

plot-sectionalplot-twomoment