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

Abstract

not Available.

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

“…For example, Abdulla et al considered H 2 recovery from a reformate mixture using a H 2 pump and summarized several additional uses including the work of Rohland et al for H 2 compression, Barbir and Gorgun for H 2 recirculation in fuel cell stacks, Sedlak et al for H 2 purification for mixed streams with specific examples cited for H 2 purification with carbon dioxide (CO 2 ) by Gardner and Ternan, and nitrogen (N 2 ) by Casati et al (1)(2)(3)(4)(5)(6). Recently, Angelo et al have demonstrated that a H 2 pump can be used to purify inert gases where H 2 was successfully separated from inert Helium (He) using a proton exchange membrane fuel cell system (PEMFCS) (7,8).…”

“…This is a costly process, however, due to challenges with liquefying the H 2 and the significant energy input required. A proton exchange membrane fuel cell operated as a H 2 pump was proposed as an alternative separation technology because the energy input is expected to be much lower than cryogenic distillation due to the facileness of the hydrogen oxidation reaction (HOR) and since system operating temperatures are much closer to ambient (7,8). Electrolytic operation was selected over galvanic operation because the He purity specifications subsequent to separation require ≤ 50 parts per million (ppm) of impurities and operating a fuel cell galvanically with air as an oxidant would result in cross-over of additional contaminants such as N 2 (7,8).…”

“…The goal was to use the value of the transport coefficient with the model to estimate the performance of larger systems. Several models have been proposed previously for determining H 2 mass transport coefficients (1,(7)(8)(9)(10)(11)(12). St-Pierre (9) provided a justification for using a differential reactor model for a galvanic cell operated at the limiting current to calculate H 2 mass transport coefficients (9) and gave a summary of the limitations of other models that used different techniques to attempt to quantify H 2 mass transport coefficients (10 -12).…”

“…To accurately compare mass transport coefficients at different operating conditions, the flow rate of all gases must be accounted for because different partial pressures of water supplied to the cell result in different H 2 concentrations. Thus, the generality of the model in (9), or more specifically, the generality of the calculated mass transport coefficient, was adjusted to account for the flow of all inert gases including water vapor and also the catalyst loading of the membrane electrode assembly (MEA) (8). This enabled a comparison of the mass transport coefficients when different amounts of water vapor were supplied to the system or when MEAs with different catalyst loadings were used to determine mass transport coefficient.…”

“…The transport coefficient in (8) was used to estimate the size of system required to remove a certain fraction of H 2 from the mixed gas stream and also to estimate the fraction of H 2 removed from a system of known size and with known inlet flow conditions. The model was found to give a good estimate of the performance of similarly sized systems with similar gas flow field designs and the same types of MEAs at the operating condition at which the transport coefficient was calculated.…”