The transport of pure gases and of binary gas mixtures through a microporous composite membrane is discussed. The membrane consists of an alumina support with a mean pore diameter of 160 nm and an alumina top (separation) layer with pores of 2-4 nm. The theory of Knudsen diffusion, laminar flow and surface diffusion is used to describe the transport mechanisms. It appears for the composite memb...

Surface exchange and oxygen vacancy diffusion dynamics were studied in double-perovskites LnBaCo2O5.5+δ (LnBCO) single-crystalline thin films (Ln = Er, Pr; -0.5 < δ < 0.5) by carefully monitoring the resistance changes under a switching flow of oxidizing gas (O2) and reducing gas (H2) in the temperature range of 250 ~ 800 °C. A giant resistance change ΔR by three to four orders of magnitude in ...

Absorption of CO2 from a gas mixture containing CO2 and nitrogen by water-based CNT nanofluids in gas–liquid hollow fiber membrane contactor was modeled and solved using COMSOL Multiphysics 5.4. The model assumed partial wetting of the membrane, along with diffusion in the axial and radial directions. In addition, Brownian motion and grazing effects were both considered in the model. The main c...

Observational evidence indicates that the bubble layer beneath the sea surface may show either an exponential or an inverse-square sound speed profile down to depths greater than 10 m. An exponential profile is consistent with a model of gas transport in which the downwardflux is due to turbulent diffusion and the d@usion coeficient is independent of depth. In this paper, a theoretical model is...

Abstract: In this research plasma nitriding of pure aluminium and effect of iron elemental alloy on the formation and growth of aluminium nitride was investigated. Also corrosion properties of formed AlN were investigated. After preparation, the samples were plasma nitrided at 550oC, for 6, 9 and 12 h and a gas mixture of 25%H2-75%N2. The microstructure and phases analysis were investigated usi...

Solid-state nuclear track detectors (SSNTDs), such as LR 115, have been commonly used in diffusion chambers for long-term measurements of radon gas concentrations. For the LR 115 SSNTD, it has been found that the active layer removed during chemical etching is significantly affected by the presence and amount of stirring, and thus cannot be controlled easily. However, the sensitivity of the LR ...

In polymer electrolyte membrane fuel cells, power losses associated with slow reaction kinetics and mass-transport limits can be strongly nfluenced by convective flow characteristics. Specifically, convection in the form of channel bypass may be utilized to simultaneously increase eactant concentration and reduce product concentration in the catalyst layer, thus reducing the activation and mass...