DMFC Performance of Polymer Electrolyte Membranes Prepared from a Graft-Copolymer Consisting of a Polysulfone Main Chain and Styrene Sulfonic Acid Side Chains
Polymer electrolyte membranes (PEMs) for direct methanol fuel cell (DMFC) applications were prepared from a graft-copolymer (PSF- g -PSSA) consisting of a polysulfone (PSF) main chain and poly(styrene sulfonic acid) (PSSA) side chains with various average distances between side chains ( L av) and side chain lengths ( L sc). The polymers were synthesized by grafting ethyl p -styrenesulfonate (EtSS) on macro-initiators of chloromethylated polysulfone with different contents of chloromethyl (CM) groups, and by changing EtSS content in the copolymers by using atom transfer radical polymerization (ATRP). The DMFC performance tests using membrane electrode assemblis (MEAs) with the three types of the PEMs revealed that: a PSF- g -PSSA PEM (SF-6) prepared from a graft copolymer with short average distances between side chains ( L av) and medium L sc had higher DMFC performance than PEMs with long L av and long L sc or with short L av and short L sc. SF-6 had about two times higher PD max (68.4 mW/cm 2 ) than Nafion ® 112 at 30 wt % of methanol concentration. Furthermore, it had 58.2 mW/cm 2 of PD max at 50 wt % of methanol concentration because of it has the highest proton selectivity during DMFC operation of all the PSF- g -PSSA PEMs and Nafion ® 112.
High-performance composite membrane based on synergistic main-chain/side-chain proton conduction channels for the vanadium redox flow battery
Synergistic proton conduction channels of side-chain SPPTA and main-chain SPEEK implement a trade-off between conductivity and permeability, and the hydrophilic/hydrophobic phase separation structure exhibits excellent VRFB performance.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.