*Kevin L Davies*: Georgia Institute of Technology, Atlanta, Georgia USA

*Christiaan J.J. Paredis*: Georgia Institute of Technology, Atlanta, Georgia USA

*Comas L. Haynes*: Georgia Institute of Technology, Atlanta, Georgia USA

Since the behavior of PEMFCs depends on both advection and diffusion; a suitable alternative to the Modelica Fluid library and the stream concept is necessary. The proposed solution uses a "mixing" scheme based on the exponential of the Peclet numbers for each transport process. Storage and transport processes are co-located in each subregion of a rectilinear grid-all in the same base model. The Onsager formulation is used; whereby the effort and flow rate are conjugates of the entropy flow rate associated with energy transfer.

The implementation is modular; it allows species to be enabled indendently for each region. In addition; the geometric axes may be independently enabled (up to 3D) and shearing (transverse momentum) may be optionally included. Chemical/electrochemical inteactions are communicated in a fully acausal manner through expandable connectors.

This paper focuses on the motivation; background; and approach. Future publications will describe the ongoing work to calibrate; validate; and utilize the model for particular case studies. The library is made available as open source.

**Keywords:** PEMFC; three dimensional; fluid dynamics; electrochemistry; heat transfer; advection; diffusion; momentum; Onsager

## Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany

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