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A set of experiments for CO 2 separation from CO 2 -N 2 mixture by absorption into water by means of a gas-liquid membrane contacting process is modelled using the mass continuity equation by combining process conditions, membrane and fluids properties, and module geometric characteristics. The general case of non-constant concentration of the diffusing component in the shell side (Case B) is used, which entails an integro-differential boundary condition at the lumen-wall. The computational method is compared with existing literature data in terms of the logarithmic averaged overall and lumen Sherwood numbers revalidating the superiority of the counter-current to the co-current mode of operation, while offering a theoretical prediction of the limited behaviour of the latter as a function of the equilibrium coefficient. The elaborate model is then applied in order to assess the extent of membrane wetting due to liquid penetration into the pores in terms of the resistance-in-series model by comparing with the experimental results derived in a commercial cross-flow membrane module under the counter-current mode of operation. It is revealed that the assumption of shell-side constant concentration (Case A) underestimates the wetting leading to a false estimation of the extent of liquid penetration into membrane pores. For Case B, a wetting-pattern appears showing a correlation of an increasing shell-side liquid flow rate with a decreasing wetting parameter and, thus, relatively less contribution of the liquid-filled membrane resistance to the overall membrane resistance with increasing liquid loading.

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It is generally accepted that carbon capture and storage strategies will play a crucial role for mitigating CO 2 emissions at short-and mid-term scenarios. In this study, a membrane gas absorption process was assessed as potential candidate method for CO 2 capture in a Greek brick production industry. The membrane contactor pilot unit was installed near the flue, where a slip stream of the flue gases was continuously sampled and fed in the hollow fiber membrane module. A 0.25 M aqueous diethanolamine solution was used as a typical solvent for CO 2 capture. The % CO 2 removal was chosen as a typical performance indicator and the liquid to gas flow ratio was chosen as the main controlling variable of the process. The test results indicate that almost complete CO 2 removal can be attained with a liquid to gas flow rate around 1, demonstrating the high potential of the proposed technology.

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The partial substitution of Ni with Cu in NiZn-ferrites has many economical advantages in bulk magnetic component manufacturing and additional densification advantages in multilayer chip inductor manufacturing. However, the detailed mechanism through which the presence of Cu influences the densification of NiZn-ferrites has not been outlined in literature. In this article the mechanism of NiCuZn-densification has been explained on basis of point defect chemistry and changes in the type of major defects that dominate ion transport through sintering. Although the densification of NiZn-ferrites is mainly dictated by the Fe content and is restricted at Fe excess, in the presence of Cu this limitation does not hold any more because of the additional anion vacancies introduced due to Cu 2+ to Cu + reduction at elevated temperatures. In addition, further Cu reduction, through the usage of reductive atmospheres, enhances the densification even further and this provides an extra processing parameter for tuning densification. There is no evidence for liquid phase sintering due to the formation of liquid phases ought to the presence of Cu or associated eutectic mixtures.

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