BIRGERSSON, Karl Erik

Assistant Professor

PhD (Fluid Mechanics) KTH Sweden, 2004
Licentiate (Fluid Mechanics) KTH Sweden, 2003
MSc (Chemical Engineering) KTH Sweden, 1998

Contact information
Blk E2, 5 Engineering Drive 2, #02-35, Singapore 117576
Tel: (65) 6516 7132    Fax: (65) 6779 1936
Email: chebke@nus.edu.sg

RESEARCH

Energy systems (Fuel cells)

In view of the increasing levels of environmental pollution and thus a desire to replace the fossil-fuel-based economy with a
cleaner alternative, fuel cells have, in recent years, emerged as prime candidates for automotive, portable and stationary applications. These fuel cells convert hydrogen or hydrocarbon fuels directly into
electricity. Understanding fuel cells calls for mathematical modeling, which has been the main objective of our research. Several models for the polymer electrolyte (PEFC) and direct methanol fuel cell (DMFC) have been derived and successfully validated with experiments. Methods used involve nondimensionalization, scaling arguments and elementary asymptotic techniques. These provide valuable insights and allow for considerable reduction of the governing set of equations, thus alleviating computational complexity and cost. Experiments have been carried out with segmented PEFC to measure local current densities and a DMFC, equipped with a transparent endplate for visualization of two-phase flow on the anode.

Drying

Drying of products containing multicomponent liquid films is performed in many industrial processes. Some of these include the manufacture of pharmaceuticals, coated laminates and magnetic storage media. In most of the applications, the drying process is of importance for the final quality of the product. It is therefore of interest to simulate the drying process in order to optimize and ensure product quality. Models for multicomponent transient drying of liquid films at high drying rates have been derived and analyzed.

Responsive materials (Hydrogels)

Recently, biosensors/actuators comprising stimuli-responsive polymeric hydrogels have attracted much attention for their potential usage in biological applications. These range from drug delivery and artifical muscles to BioMEMS devices such as microvalves and microfluidic controllers. Such potential stems from the capability of hydrogels to undergo large volume changes when subjected to outer stimuli, in particular to changes in pH, temperature and electric fields. This volume change is associated with a wide range of physical phenomena, requiring a blend of continuum mechanics, material science and
electrochemistry to properly model the kinetics. In short, these models are necessary for elucidating the inherent transport processes that occur during the swelling/deswelling of the hydrogels, for improving the design and materials, as well as allowing for fast models that can be incorporated in system studies. Models have been derived for slow- and fast-response hydrogels subject to temperature stimuli. Due to the finite deformations that occur, a total Lagrangian formulation for the hydrogel coupled with an Arbitrary Lagrangian Eulerian (ALE) formulation, i.e. a moving mesh, for the external field has been implemented.

SELECTED PUBLICATIONS

E. Birgersson and M. Vynnycky, "A Quantitative Study of the Effect of Flow-Distributor Geometry in the Cathode of a PEM Fuel Cell", Journal of Power Sources, 153 (1), 76-88 (2006).

E. Birgersson, M. Noponen and M. Vynnycky, "Analysis of a Two-phase Non-Isothermal Model for a PEFC", Journal of The Electrochemical Society, 152 (5), A1021-A1034 (2005).

Vynnycky and E. Birgersson, Mathematical Modelling of Fuel Cells: From Analysis to Numerics, book chapter in Transport Phenomena in Fuel Cells, B. Sunden \& M. Faghri (eds), WIT Press (2005).

Luna, E. Birgersson and J. Martinez, "Diffusion equation applied to isothermal drying of a multicomponent liquid film", Drying Technology, 23 (9-11), 1953-1975 (2005).

E. Birgersson, J. Nordlund, M. Vynnycky, C. Picard and G. Lindbergh, " Reduced Two-Phase Model for Analysis of the Anode of a DMFC", Journal of the Electrochemical Society, 151 (12), A2157-A2172 (2004).