Thermodynamics of Nafion™–vapor interactions. I. Water vapor

On the temperature distribution in polymer electrolyte fuel cells

“…When water vapour absorbs in Nafion, a heat source is applied as 44.7 kJ mol −1 , and when water desorbs to the vapour phase, a heat sink is applied as −44.7 kJ mol −1 . These values have been measured by Reucroft et al [17] for water contents greater than = 5. According to these measurements, there is no heat sink or source when liquid water enters or leaves the membrane for > 5.…”

Effects of hydrothermal/thermal treatments on the water-uptake of Nafion membranes and relations with changes of conformation, counter-elastic force and tensile modulus of the matrix

“…Concerning vapour sorption isotherms, Fig. 5 shows a comparison of some curves obtained by various authors for Nafion 117 membranes [6,7,9,10]. In our opinion, the large discrepancies between these curves cannot be attributed to experimental errors but they are reasonably due to different initial conformations of Nafion samples used in the various laboratories (see later).…”

Heat sources in proton exchange membrane (PEM) fuel cells

“…In [35], the authors observed that the sorption enthalpy of water in Nafion 117 varies with the membrane hydration and that it is dependent on pre-treatment. However, no general trends can be drawn.…”

“…Enthalpy sorption (kJ mol −1 ) Reference Comments 46 [38] For Nafion 112 For aw > 0.2 From 60 to 43 [37] For Nafion 112 Decreasing with increasing water uptake From 52.3 to 16.7 [39] For Nafion 117 For aw > 0.2 Decreasing with increasing water uptake 28 [40] For Nafion 117 For aw > 0.2 From 45 to 110 [35] For Nafion 117 A function of water uptake and Nafion pretreatement 45 [36] For Nafion 117 43 [41] For non-sulfonated polyimide membranes From 52 to 45 [36] For sulfonated polyimide membranes Decreasing with an increasing water uptake one side of the membrane is in contact with dry hydrogen while the other is in contact with humidified air). This phenomenon is neglected in most of the thermal studies.…”