Cross-leak

In addition to optimal bulk conductivity the contact resistance at the surface of the bipolar plate has also to be reduced as much as possible. Gas tightness is required to prevent leaks to the exterior as well as cross-leaks between the fluids in the stack. 

Keywords Analysis Cross leak degradation High temperature membrane Perfluorosulfonic acid PFSA Reinforcement... 

High temperature DMFC low cross leak of methanol... 

Decrease in swelling and methanol cross leak of membranes in DMFC applications is one of the most important development items, and various efforts and trials have been performed to improve these characteristics for both perfluorinated and hydrocarbon membranes. 

The development of high temperature membranes applicable to operation at up to 120 °C or higher, no or low humidity, and low pressure conditions has been expected to offer better efficiency and more compact stacks and radiators for automobiles. These expectations for membranes are typically reflected by the DOE s 2010 targets shown in Table 1. Operation at higher temperature (120 °C) and lower humidity (1.5 kPa), lower cross leak, lower... 

In recent years, PVA has been used as PEM for fuel cell applications [11-16]. Furthermore, it shows unique characterizations of good resistance to organic solvent and superior methanol barriers to Naflon, where the alcohol cross leak is a key issue in practical uses for direct methanol fuel cells (DMFCs). Since no ionic group is contained in the side chains, acid or basic groups should be introduced through ionic polymers or ionic solution. 

Cross-country gas pipelines generally must odorize the normally odorless, colorless, and tasteless gas ia urban and suburban areas, as is required of gas distribution companies. Organosulfur compounds, such as mercaptans, are usually used for this purpose, and code requires that the odor must be strong enough for someone with a normal sense of smell to detect a gas leak iato air at one-fifth the lower explosive limit of gas—air mixtures. The latter is about 5%, so the odorant concentration should be about 1%, but most companies odorize more heavily than this as a safety precaution. 

The modulus of elasticity can also influence the adhesion lifetime. Some sealants may harden with age as a result of plasticizer loss or continued cross-linking. As a sealant hardens, the modulus increases and more stress is placed on the substrate—sealant adhesive bond. If modulus forces become too high, the bond may faH adhesively or the substrate may faH cohesively, such as in concrete or asphalt. In either case the result is a faHed joint that wHl leak. 

It is generally desirable to minimize the diameter of a tubular reactor, because the leak rate in case of a tube failure is proportional to its cross-sectional area. For exothermic reactions, heat transfer will also be more efficient with a smaller tubular reactor. However, these advantages must be balanced against the higher pressure drop due to flow through smaller reactor tubes. 

Pipe AP above leak 477 psi Pipe AP below leak 646.5 psi AP across leak 312.5 psi Leak cross-section 0.24 in. - ... 

Static leak-off experiments with borate-crosslinked and zirconate-cross-Unked hydroxypropylguar fluids showed practically the same leak-off coefficients [1883]. An investigation of the stress-sensitive properties showed that zirconate filter-cakes have viscoelastic properties, but borate filter-cakes are merely elastic. Noncrosslinked fluids show no filter-cake-type behavior for a large range of core permeabilities, but rather a viscous flow dependent on porous medium characteristics. 

Plasma colloid osmotic pressure is generated by proteins in the plasma that cannot cross the capillary wall. These proteins exert an osmotic force, pulling fluid into the capillary. In fact, the plasma colloid osmotic pressure, which is about 28 mmHg, is the only force holding fluid within the capillaries. Interstitial fluid colloid osmotic pressure is generated by the small amount of plasma proteins that leaks into the interstitial space. Because these proteins... 

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