Thermodynamic modeling of carbon dioxide adsorption in aqueous methyl diethanolamine using cubic plus association equation of state (CPA)

The vapor liquid equilibrium of the 3-component system composed of carbon dioxide, water, and methyl diethanolamine has been modeled by the cubic plus association equation of state in a wide range of temperatures (313–433 K), pressures (0.775–4,930 kPa), and methyl diethanolamine wt% (5–75). Carbon dioxide has been considered in two states in this approach: (1) an accumulative molecule bearing the structural shape of 4C and 3B, and (2) a noncumulative molecule. The results obtained from the cubic plus association equation of state showed a good compatibility with the experimental data for the 3-component system. Comparing the results gathered from the Clegg-Pitzer and N-Wilson-NRF models reveals that the cubic plus association model leads to more convincing results than both of them. Furthermore, results obtained from the 4C cumulative design for carbon dioxide in the cubic plus association equation of state shows a lesser error compared to 3B cumulative design and to no designs.     

Design and development of a low cost technique for sorting household wastes using eddy current separation process

Recovery and recycling of metals from wastes have a major role in the global economy because of the scarcity of raw materials and the problem of environmental pollution. This paper reports a technical and economic study for the development of a low-cost eddy-current separator for household waste treatment. Waste treatment in African countries suffers a developmental delay owing to the cost of such equipment. On the basis of preliminary results obtained by numerical simulation of the physical phenomena, in order to test several possible configurations, a prototype device has been built and tested. The experimental results obtained have led to an optimal configuration in terms of separation efficiency. Thus, a second more efficient device has been successfully developed and tested. The economic analysis revealed the benefit of local manufacture for such a separator.     

Nisin‐loaded alginate‐high methoxy pectin microparticles: preparation and physicochemical characterisation

The bacteriocin nisin has been extensively used as potential natural preservative in the food industry. However, antimicrobial activity of nisin due to its binding with food components and inactivation by enzymatic degradation is reduced when it is applied in food. Encapsulation of nisin is an efficient approach to overcome the problems related to the direct application of this antimicrobial peptide in foods. In this study, nisin was encapsulated in alginate‐high methoxy pectin (HMP) microparticles, and its release studies were performed in water to determine the diffusion and the kinetic behaviour of the matrix. Results showed that the nisin content had a significant influence on encapsulation efficiency (EE), loading capacity (LC) and microparticles size. The values of EE, LC and particle mean diameter were about 47–54%, 16–21% and 57–131 μm, respectively. The nisin‐loaded microparticles showed nearly spherical structure with fold on the surface, as displayed by scanning electron micrograph. Interaction between alginate and HMP was confirmed by the changes in the intensity and wave number of the stretching vibrations of the hydroxyl and carboxyl groups in alginate‐HMP microparticles FTIR spectra. Furthermore, the addition of nisin resulted in a markedly increase in intensity of carboxylic peak at 1620 cm^?1, indicating the presence of nisin inside of the microparticles. The in vitro nisin release from these microparticles followed a sustained release profile consistent with a Fickian diffusion mechanism.     

Thermal comfort analysis of earth-sheltered buildings: The case of meymand village,Iran

Vernacular buildings are known for their localized passive settings to provide comfortable indoor environment without air conditioning systems. One alternative is the consistent ground temperature over the year that earth-sheltered envelopes take the benefit; however, ensuring annual indoor comfort might be challenging. Thus, this research monitors the indoor thermal indicators of 22 earth-sheltered buildings in Meymand, Iran with a warm-dry climate. Furthermore, the observations are used to validate the simulation results through two outdoor and indoor environmental parameters, air temperature and relative humidity during the hottest period of the year. Findings indicated that the main thermal comfort differences among case studies were mainly due to their architectural layouts where the associated variables including length, width, height, orientation, window-to-wall ratio, and shading depth were optimized through a linkage between Ladybug-tools and Genetic Algorithm (GA) concerning adaptive thermal comfort model definition and could enhance the annual thermal comfort by 31%.     

Thixoforming A356 Aluminum Bipolar Plates at High Solid Fractions

Thixoforming investigations have been developed primarily for the manufacturing of bulk components, and the current knowledge is very limited with respect to the fabrication of thin cross sections of alloys. We studied the effectiveness of thixoforming process for the fabrication of A356 aluminum alloy bipolar plates with microchannels on both sides. Feedstock semisolid slurries, with different solid contents of ~55, 50, and 45 pct, were prepared at 858 K, 863 K, and 868 K (585 °C, 590 °C, and 595 °C), respectively, and were used to thixoform 1.20-mm-thick bipolar thin plates. The microstructures of the thixoformed thin plates consisted of (i) large primary α-Al globular grains, (ii) a quenched liquid phase, and (iii) fine secondary α-Al particles. The fraction and size of the primary α-Al globular grains decreased, and the primary α-Al globular grains became more spherical with the increasing thixoforming temperature. It seemed that these changes in the microstructural features led to the reduction in the agglomeration and interaction among the primary α-Al globular grains surrounded by the liquid matrix during thixoforming. This enabled the semisolid slurry to effectively flow and fill in the sharp corners (such as the microchannels) of the die cavity at higher thixoforming temperatures. The thin plates thixoformed at 868 K (595 °C), consequently, exhibited the highest dimensional stability and the fewest internal defects. The liquid matrix surrounding the primary α-Al grains solidified inside the die cavity after thixoforming. Either the liquid phase was instantly quenched or fine secondary α-Al particles were formed inside the die cavity. The fraction and size of the latter increased with increasing thixoforming temperature. The surface hardness of the thixoformed plates was measured, and the hardness values were correlated with the microstructural features of the thixoformed plates.