Dynamic Simulation of a High Temperature Polymer Electrolyte Membrane Fuel Cell: Stack Performance

Abstract

One of the attractions of high temperature polymer electrolyte membrane (PEM) fuel cell is the quality of the heat co-produced with power that could be recovered for use in a combined heat and power system. In this study, a one-dimensional model for a single PEM fuel cell was developed and implemented in Engineering Equations Solver (EES) environment to express the cell voltage as a function of current density among others. The single cell model was employed to investigate the energetic behaviour of a 1 kWe high temperature PEM fuel cell stack system, and the corresponding power and thermal efficiencies at different operating modes. A multiple parametric analyses using the built-in EES uncertainty propagation tool was used to determine the stack performance for the selected parameter range. The influence of the stack operating temperature, hydrogen utilization, the carbon monoxide content in the anode gas feed and the current density, on the efficiency of the fuel cell stack were studied at the required stack electrical output. The study showed that an increase in temperature increased the stack electrical power output whilst the thermal output decreased. The stack electrical power output was seen to increase with increase in the current density and hydrogen stoichiometry. It can be seen that ratio between the electrical power and thermal output increased as the current density increases. This ratio becomes unity at an operating current density of 0.3 A/cm², representing the optimal operating current density of the stack. An increase in the hydrogen utilization has positive effects on both the cogeneration and thermal efficiency.

Key findings

• ▸Increasing the stack operating temperature increases the stack electrical power output.
• ▸Thermal output decreases with increasing temperature.
• ▸Hydrogen utilization, carbon monoxide content, and current density have significant effects on stack efficiency.

Keywords

Identifiers

DOI

10.1115/fuelcell2012-91509

Journal

ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology

Year

2012