Estimation of the CO2-oil minimum miscibility pressure for enhanced oil recovery

The authors' aim was to present new models based on artificial neural network (ANN) and two optimization algorithms including cuckoo optimization algorithm (COA) and teaching learning based optimization (TLBO) to predict the pure and impure CO₂ MMP. Thirty-four and 11 training and testing data sets were used to develop these models with following inputs: reservoir temperature, the mole percent of volatile oil components (C₁ and N₂), mole percent of intermediate oil components (C₂-C₄, CO₂, and H₂S), molecular weight of C₅₊ fraction in oil phase (MW_C5+) and mole percentage of CO₂, N₂, C₁, C₄, and H₂S in the injected gas. Statistical comparisons show that although two models yield acceptable results, the ANN-TLBO model has better performance with the lower mean absolute percentage error (2.6%) and standard deviation (3.37%) and the higher coefficient of determination (0.993). Moreover, among the available correlations, the Cronquist's (1978 Cronquist, C. (1978). Carbon dioxide dynamic miscibility with light reservoir oils. Fourth Annual U.S. DOE Symposium, Tulsa, Oklahoma. [Google Scholar]; corrected by Sebastian et al., 1985 Sebastian, H. M., Wenger, R. S., and Renner, T. A. (1985). Correlation of minimum miscibility pressure for impure CO2 streams. J. Pet. Technol. 37:2076–2082.[Crossref] , [Google Scholar]) correlations have better performance. Finally, the sensitivity analysis on the ANN-TLBO showed that MW_C5+ and reservoir temperature are the most influential parameters in determining the CO₂ MMP, respectively.     

A study on the effects of Fex/Niy/MgO(1−x−y) catalysts on the volumetric and electrochemical hydrogen storage of multi-walled carbon nanotubes

The effects of various ratios of Fe/Ni/MgO and growth temperatures on yield, diameter and quality of multi-walled carbon nanotubes (MWCNTs) were studied. Thermal gravimetric analysis (TGA) confirmed that the MWCNT yield depends on Fe/Ni ratio with the following order; Fe_0.5 Ni_0.5 > Fe > Fe_0.75 Ni_0.25 > Fe_0.25 Ni_0.75 > Ni. The results indicated that there is an optimum temperature (940 °C) for the MWCNT growth both from quality and quantity (yield) aspects as compared to other temperatures. Moreover, the changes on Fe/Ni to MgO ratio for the MWCNT growth revealed that Fe/Ni/MgO with the ratio of 17.5/17.5/65 had the highest quality and surface area as compared to the other ratios. The hydrogen storage capacities of MWCNTs grown on Fe/Ni/MgO with various ratios obtained by using volumetric technique were in ascending order as 17.5/17.5/65, 15/15/70, 12.5/12.5/75, 10/10/80, 20/20/60, 22.5/22.5/55 and 25/25/50. In addition, the defective sites and mean diameter of the MWCNTs influenced the desorption temperature of stored hydrogen. Hydrogen storage by using electrochemical technique showed that Fe/Ni/MgO with the ratio of 17.5/17.5/65 had the highest hydrogen storage capacity compared with the other ratios. Based on electrochemical analysis, there are two regimes for hydrogen adsorption on the MWCNTs, one at about 0.8 V and the other at 0.15 V. The study on two kinds of adsorption region showed that the ratio of hydrogen storage capacity at 0.8 V to hydrogen storage capacity at 0.15 V increased with the increasing of the mean diameter of MWCNTs. The ratio reached to maximum value for the MWCNTs grown on Fe/Ni/MgO with the ratio of 20/20/60 as compared to the other ratios.     

Aquaporin-Based Biomimetic Membranes for Low Energy Water Desalination and Separation Applications

The emergence of biomimetic materials developed using nature's inspiration and biological domains can drive a paradigm shift in the design and operation of future-generation materials in separation applications. In recent years, biomimetic membranes have drawn interest of many researchers for water treatment applications. Among the biomimetic membranes, protein-based membranes, specifically those synthesized by aquaporin, have received much attention in recent years due to their high osmotic water permeability and excellent ability to remove small molecules, thereby overcoming the trade-off between the water flux and the contaminant's rejection. The separation efficiency and fouling properties are significantly improved by taking advantage of the strategies evolved in nature. This review provides a comprehensive overview of the state-of-the-art aquaporin-based biomimetic membranes (ABMs), mainly focusing on their synthesis, characterization, and performance as selective layer in composite membranes for reverse osmosis, nanofiltration, and forward osmosis for water desalination. Fabrication methods and characterization techniques of ABMs and their performance in water desalination are also reviewed, while the main obstacles for their successful commercial viability in wastewater treatment are provided. The applications of ABMs in various separation processes other than water desalination and their potential market are presented to inspire future researchers in this versatile area.     

Regional energy system optimization – Potential for a regional heat market

Energy supply companies and industrial plants are likely to face new situations due to, for example, the introduction of new energy legislation, increased fuel prices and increased environmental awareness. These new prerequisites provide companies with new challenges but also new possibilities from which to benefit. Increased energy efficiency within companies and increased cooperation between different operators are two alternatives to meet the new conditions. A region characterized by a high density of energy-intensive processes is used in this study to find the economic potential of connecting three industrial plants and four energy companies, within three local district heating systems, to a regional heat market, in which different operators provide heat to a joint district heating grid. Also, different investment alternatives are studied. The results show that the economical potential for a heat market amounts to between 5 and 26 million EUR/year with payback times ranging from two to eleven years. However, the investment costs and the net benefit for the total system need to be allotted to the different operators, as they benefit economically to different extents from the introduction of a heat market. It is also shown that the emissions of CO₂ from the joint system would decrease compared to separate operation of the systems. However, the valuation of CO₂ emissions from electricity production is important as the difference of emitted CO₂ between the accounting methods exceeds 650 kton/year for some scenarios.     

Melamine–formaldehyde curing acceleration by TiO2-based silver-white pigments catalysis

European Journal of Wood and Wood Products - The preparation of melamine–formaldehyde (MF) resins for paper impregnation for wood panels laminating was found to be catalyzed by TiO2-mica...