: 1h nmr spectra of a series of enaminones r-co-ch=c(nhch2ph)-r  [1, r=ch3; 2, r=c6h5; 3, r=cf3; 4, r=ch2ch2ch2; 5, r=ch2c(ch3)2ch2], were obtained in the presence of trifluoroacetic acid in cdcl3 or dmso-d6 at 28 °c. steric, solvent, electronic and hydrogen bonding effects on the rates of acid-catalyzed nh proton exchanges were investigated. rate constants were calculated by 1h nmr line shape ...

an essential requirement for an operating pem fuel cell is providing proper water content in the membrane. to avoid water flooding an appropriate water balance is required. here, an analytic model of a planar membrane humidifier for pem fuel cell is proposed where the effect of dimensional parameters includes membrane thickness, membrane area and channel hydraulic diameter are investigated. a n...

Proton exchange membrane fuel cells have been receiving more and more attention these recent years. Maintaining a fuel cell system in correct operating conditions requires good controller. Based on the mathematical model of proton exchange membrane fuel cells described in this paper, the fuzzy logic controllers was designed for the proton exchange membrane fuel cell to make it possible to outpu...

In this study, a series of sulfonated hydrocarbon pentablock terpolymers (NEXAR® Polymers) with different ion exchange capacities (1.0, 1.5, and 2.0 meq g−1) were characterized investigated as membranes ionomers in hydrogen fuel cells. All NEXAR® Membranes exhibited higher proton conductivity (>0.2 S cm−1 at 80 °C, 90% RH) than Nafion (the most frequently used polymer membrane cells). The Membr...

in the polymer electrolyte membrane fuel cells (pemfcs), low corrosion resistance and high interfacial contact resistance (icr) are two controversial issues in usage of aisi 316l stainless steel as a metallic bipolar plate. for solving these problems, investigation and development of different coatings and/or surface treatments are inevitable. corrosion behavior and icr of aisi 316l specimens c...

An essential requirement for an operating PEM fuel cell is providing proper water content in the membrane. To avoid water flooding an appropriate water balance is required. Here, an analytic model of a planar membrane humidifier for PEM fuel cell is proposed where the effect of dimensional parameters includes membrane thickness, membrane area and channel hydraulic diameter are investigated. A N...

Recent advances in developing hydrocarbon-based proton-exchange membrane fuel cells have focused on optimizing materials. Voltage recovery (VR) has shown notable improvements for perfluorosulfonic acid-based cells. This study is the first to present a VR protocol designed specifically The proposed involves 100 voltage steps at 0.08 V and 0.12 V, lasting 20 seconds each, 80 °C, under backpressur...

Proton exchange membrane fuel cells are promising energy sources that produce electrical currents with almost null pollutant emissions, and they have been received growing attention in recent years. Maintaining a fuel cell system in correct operating conditions requires good system control. Based on the mathematical model of proton exchange membrane fuel cells, model linearization is carried ou...