For industrial applications, the two-fluid model is preferred due to its efficient modelling of small-scale interfaces. Whereas, a thin film model, based on a long wave approximation, is used for the unresolved interfaces to obtain the film features by solving the 2D Navier-Stokes equations for wall films. Within the project, the target is to develop an experimentally validated 3D-CFD model to investigate the separation efficiency of droplet separators for fuel cell systems. A hybrid model is developed, which couples the two-fluid model with a thin film model via mass transfer terms for droplet deposition, droplet entrainment and film separation. A two-way coupling between droplets and the thin film is established using mass and momentum source terms, derived analytical and from available experiments. The droplet separator is an essential component of an automotive fuel cell system that segregates a significant amount of liquid fractions from the air-water mixture. The flow dynamics inside a droplet separator consist of a dispersed gas and liquid with a wall adhered thin liquid film. The modelling is divided into the following stages due to the complex fluidic phenomenon inside a generic droplet separator:

Droplet deposition model,
Film separation model,
Film transition model, and
Population balance model.

The numerical simulations are validated and fine-tuned with experiments carried out at HZDR.

The research project was self-financed (FVV funding no. 1455) by the FVV e.V.