Mind the Gap: Bridging Molecular and Fluid Dynamics Simulations in the Polyurethane Foam Industry

In a previous work, a novel approach, based on the incorporation of Computational Fluid Dynamics (CFD) with the Population Balance Equation (PBE) was developed and applied for the first time to the simulation of expanding polyurethane foams. The model included a simple but realistic representation of the polymerization kinetics. The model also accounted for the presence of a physical blowing agent and of a chemical blowing agent. Notwithstanding its simplicity, a good agreement with experimental data was obtained. Yet, some limiting assumptions were adopted in the development of this approach, as follows:

1) the density of the polymerizing liquid mixture, assumed fixed to a constant value and, as such, independent of temperature and degree of cross-linking;

2) the temperature dependence of the solubility of the physical blowing agents (e.g., R-11, in the case of physically blown foams) and of the produced carbon dioxide (in the case of chemical blown foams).

To fill this gap in the present work we present an implemented version of this approach according to which molecular simulations are employed to calculate the missing quantities at points 1) and 2), and their link to the CFD code for the more realistic simulation of expanding physically and chemically blown foams.

This work was funded by the European Commission under the grant agreement number 604271 (Project acronym: MoDeNa; project identifier: FP7-NMP-2013-SMALL.