Solid-polymer-electrolyte fuel cells

Technical Report · Wed Jul 01 04:00:00 EDT 1992

DOI:https://doi.org/10.2172/7001224· OSTI ID:7001224

Fuller, T F

A transport model for polymer electrolytes is presented, based on concentrated solution theory and irreversible thermodynamics. Thermodynamic driving forces are developed, transport properties are identified and experiments devised. Transport number of water in Nafion 117 membrane is determined using a concentration cell. It is 1.4 for a membrane equilibrated with saturated water vapor at 25{degrees}C, decreases slowly as the membrane is dehydrated, and falls sharply toward zero as the water content approaches zero. The relation between transference number, transport number, and electroosmotic drag coefficient is presented, and their relevance to water-management is discussed. A mathematical model of transport in a solid-polymer-electrolyte fuel cell is presented. A two-dimensional membrane-electrode assembly is considered. Water management, thermal management, and utilization of fuel are examined in detail. The membrane separators of these fuel cells require sorbed water to maintain conductivity; therefore it is necessary to manage the water content in membranes to ensure efficient operation. Water and thermal management are interrelated. Rate of heat removal is shown to be a critical parameter in the operation of these fuel cells. Current-voltage curves are presented for operation on air and reformed methanol. Equations for convective diffusion to a rotating disk are solved numerically for a consolute point between the bulk concentration and the surface. A singular-perturbation expansion is presented for the condition where the bulk concentration is nearly equal to the consolute-point composition. Results are compared to Levich's solution and analysis.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7001224
• Report Number(s): LBL-32577; ON: DE92041204
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
300500* -- Fuel Cells
COMPUTER CODES
CONVECTION
DIFFUSION
DIRECT ENERGY CONVERTERS
ELECTROCHEMICAL CELLS
ELECTROLYTES
ENERGY TRANSFER
FUEL CELLS
HEAT TRANSFER
HYDROGEN COMPOUNDS
MASS TRANSFER
MATHEMATICAL MODELS
MEMBRANES
OXYGEN COMPOUNDS
POLYMERS
SOLID ELECTROLYTE FUEL CELLS
SOLID ELECTROLYTES
THERMODYNAMICS
WATER