Calculating Hydrogen Mass Transport Coefficients in a PEMFC at Different Operating Conditions Using a Hydrogen Pump Configuration

Abstract

A proton exchange membrane fuel cell system (PEMFCS) operated electroytically at its limiting current was proposed previously as a technology to separate H 2 and He through the electrochemical oxidation of H 2 . In this work the fraction of H 2 remaining in the effluent of two different sized PEMFCs with different flow field designs was studied at several operating conditions which included different: system temperatures, inlet relative humidity (R.H.), and system pressures to determine the most efficient operating condition. Experiments were performed at a fixed dry gas flow rate with an inlet H 2 dry gas fraction of 10 %. System performance was found to depend significantly on operating conditions with optimum performance attained at 60 ºC and 100 % R.H. for both system sizes. To assist in the performance modeling of each system a differential chemical reactor model was used to determine H 2 mass transport coefficients at each operating condition.

A Study of the Durability and Performance of a Proton Exchange Membrane Electrode Assembly Used in the Separation of Hydrogen From Helium

“…Previous work demonstrated that a PEMFC operated as an electrolytic cell at the limiting current could attain outlet streams with less than 50 parts per million (ppm) H 2 by controlling the flow rate of gases in the feed (1). The fuel cell operating conditions that resulted in the greatest He purity were also identified (2). However, the effects of continuous operation for an extended duration on the fraction of H 2 removed by the PEMFC (i.e.…”