Performance of high temperature PEM fuel cell materials. Part 1: Effects of temperature, pressure and anode dilution

Abstract

High temperature proton exchange membrane (HT-PEM) fuel cells operate most effectively at temperatures 160 o C or greater and can tolerate high carbon monoxide concentrations in fuel feeds. For practical mobile fuel cell systems, the ability to tolerate high levels of carbon monoxide enables a simplified integrated reformer fuel cell design, where a one-step reforming process can directly feed the fuel cell. This creates the potential for practical fuel cell systems to be designed that are capable of operating using an on-board hydrocarbon fuel. Hydrocarbon reforming processes (i.e., partial oxidation, steam reforming, or autothermal reforming) generate effluent gas compositions that typically contain various amounts of hydrogen, carbon monoxide, carbon dioxide, nitrogen, and water. While there are several studies that have examined the effects of CO dilution on HT-PEM fuel cell performance, there are very few that have examined the effects of other common reformate species, particularly while operating at varying temperatures and pressures. This work aims to fill the research gap in published data through evaluation of the performance exhibited by two HT-PEM membrane-electrode assembly (MEA) types, Advent's TPS ©-based MEA and the BASF Celtec series MEA, based on acid-doped polybenzimidazole (PBI). In Part I of this series, the effects of temperature and pressure for various percentages of anode dilution were investigated. Temperatures and pressures were varied from 160 to 200 o C and 101.3 to 200 kPa, respectively. The effect of hydrogen diluted with nitrogen in the anode feed was examined with nitrogen concentrations up to 70%. Overall, the PBI MEA provided greater performance than the TPS for all tested conditions. Our results show that the performance loss due to high dilution levels can be wholly mitigated by an increase in operating temperature, pressure, or a combination thereof. For example, even at a dilution level containing 70% nitrogen, operating the cell at 200 o C and at 200 kPa provides the same power output as running the cell on pure hydrogen at 160 o C and at atmospheric pressure. This data can be used to model the performance effect of high diluent concentrations in the anode gas feed when developing an integrated reformer/fuel cell system.

Numerical Analysis of Temperature Distributions in Single Cell of Polymer Electrolyte Fuel Cell when Operated in Elevated Temperature Range

“…Some studies [14][15][16][17][18][19][20][21][22][23][24][25][26] have investigated PEFC operated under elevated temperature than usual. Although the dynamic power generation characteristics [14][15][16][17][18][19], the degradation test [20][21][22], the water distribution [23], the power generation performance under different temperatures, relative humidity, gas flow rate and pressure [24,25] have been investigated, there have been a few reports [26,27] on temperature distribution in the cell of PEFC. Especially, the temperature distribution on "reaction surface" has not been investigated yet, except in our former study [28] using the proposed heat transfer model.…”

A coupled and interactive influence of operational parameters for optimizing power output of cleaner energy production systems under uncertain conditions

“…In different researches, operating parameters, viz, temperature, pressure, and current density, have been usually thought to be the main factors that influence the output power of PEMFC . Recently, a research has used a new methodology: moment‐based uncertainty evaluation technique, a framework which is accurate and reliable to study the influence of some uncontrollable factors, viz, SC, stack temperature (ST), oxygen excess ratio (OER), inlet air humidity (IAH), and hydrogen excess ratio (HER) . To some extent, these uncontrollable factors have a bad influence on the output power and operation of the fuel cell .…”

“…[8][9][10][11] Recently, a research has used a new methodology: moment-based uncertainty evaluation technique, a framework which is accurate and reliable to study the influence of some uncontrollable factors, viz, SC, stack temperature (ST), oxygen excess ratio (OER), inlet air humidity (IAH), and hydrogen excess ratio (HER). 3,[12][13][14][15][16][17][18][19][20][21][22] To some extent, these uncontrollable factors have a bad influence on the output power and operation of the fuel cell. 2 However, the relation between the output power and these parameters cannot be explicitly represented by a mathematical function, because the PEMFC system is multi-dimensional and complex, which cannot be modeled by experiments or by trial-and-error approach.…”

An Experimental Method to Measure Flow Distribution in the Cathode of High‐Temperature Polymer Electrolyte Membrane Fuel Cells Stack

“…For λ ≥ 2@0.2 A cm À2 (the air flow is more than 0.3 L min À1 ), as the temperature raises, the activation polarization loss and the ohm polarization loss decrease, so the cell voltage increases. [26] For λ < 2@0.2 A cm À2 (the air flow is less than 0.3 L min À1 ), as the temperature rises, the cell voltage increases, which is mainly caused by the reduction of mass transfer polarization loss. [27] The effect of temperature on oxygen transfer in the HT-PEMFC cathode and the effect of temperature on K are different, so it is necessary to ensure the same temperature when using this method to quickly evaluate and screen the cathode diffusion layer.…”