Design and analysis of a solar tower power plant integrated with thermal energy storage system for cogeneration

In the current study, a solar tower–based energy system integrated with a thermal energy storage option is offered to supply both the electricity and freshwater through distillation and reverse osmosis technologies. A high‐temperature thermal energy storage subsystem using molten salt is considered for the effective and efficient operation of the integrated system. The molten salt is heated up to 565°C through passing the solar tower. The thermal energy storage tanks are designed to store heat up to 12 hours. The temperature variations in the storage tanks are studied and compared accordingly for evaluation. The effect of operating temperatures on the freshwater production and overall system efficiency is determined. About 24.46 MW electricity is generated in the steam turbine under sunny conditions. Furthermore, the storage subsystem stores heat during sunny hours to utilize later in cloudy hours and night time. The produced power decreases to 20.17 MW in discharging hours due to temperature decrease in the tank. The electricity generated by the system is then used to produce freshwater through the reverse osmosis units and also to supply electricity for the residential use. A total flowrate of 240.02 kg/s freshwater is obtained by distillation and reverse osmosis subsystems.     

Frontiers in combustion techniques and burner designs for emissions control and CO2 capture: A review

The use of fossil fuel is expected to increase significantly by midcentury because of the large rise in the world energy demand despite the effective integration of renewable energies in the energy production sector. This increase, alongside with the development of stricter emission regulations, forced the manufacturers of combustion systems, especially gas turbines, to develop novel combustion techniques for the control of NO_x and CO₂ emissions, the latter being a greenhouse gas responsible for more than 60% to the global warming problem. The present review addresses different burner designs and combustion techniques for clean power production in gas turbines. Combustion and emission characteristics, flame instabilities, and solution techniques are presented, such as lean premixed air‐fuel (LPM) and premixed oxy‐fuel combustion techniques, and the combustor performance is compared for both cases. The fuel flexibility approach is also reviewed, as one of the combustion techniques for controlling emissions and reducing flame instabilities, focusing on the hydrogen‐enrichment and the integrated fuel‐flexible premixed oxy‐combustion approaches. State‐of‐the‐art burner designs for gas turbine combustion applications are reviewed in this study, including stagnation point reverse flow (SPRF) burner, dry low NO_x (DLN) and dry low‐emission (DLE) burners, EnVironmental burners (including EV, AEV, and SEV burners), perforated plate (PP) burner, and micromixer (MM) burner. Special emphasis is made on the MM combustor technology, as one of the most recent advances in gas turbines for stable premixed flame operation with wide turndown and effective control of NO_x emissions. Since the generation of pure oxygen is prerequisite to oxy‐combustion, oxygen‐separation membranes became of immense importance either for air separation for clean oxy‐combustion applications or for conversion/splitting of the effluent CO₂ into useful chemical and energy products. The different carbon‐capture technologies, along with the most recent carbon‐utilization approaches towards CO₂ emissions control, are also reviewed.     

Impact of graphite impurities on the structure and optical properties of the sodium borate oxide glass

For the carbon-based glass fabrication/manufacture process, different amounts of pure graphite powder were added up to 100 wt.% of sodium tetraborate oxide (the weight of one mole of the sodium tetraborate is 381.372 g/mol) and then melted at 950 °C for 2 h before fast quenching in the air at RT. The resulted solids were examined by the XRD and SEM techniques, which confirmed the amorphous natures for studied samples. FTIR spectroscopy showed that some C-atoms are shared in the glass network as C–O and CO₂. In contrast, the UV–Vis showed that the increase in the graphite contents/impurities causes a red shift in the value of the optical edge and the value of Fermi energy. Also, the increase of the graphite impurities causes a decrease in the bandgap values of both direct and indirect electronic transitions. Both the values of Urbach energy and the metallization indicated an increase in the crystallinity degree as the graphite content increase. A graphite-based glass is a promising material for wide-scale applications.

     

A green approach for modification and functionalization of wool fabric using bio- and nano-technologies

In the present work, we propose a green and sustainable strategy for eco-friendly surface modification of wool structure using biosynthesized kerationlytic proteases, from C4-ITA-EGY, Streptomyces harbinensis S11-ITA-EGY and Streptomyces carpaticus S33-ITA-EGY, followed by subsequent environmentally sound functionalization of the bio-treated substrates using ZnONPs, ZrO₂NPs, ascorbic acid and vanillin, individually, to provide durable antibacterial as well as UV-protection properties. Both surface modification changes and the extent of functionalization of the final products were characterized by SEM, EDX, antibacterial efficacy, UV-blocking ability, loss in weight, nitrogen content and durability to washing analysis. The obtained data reveal that the developed green wool fabrics exhibit outstanding durable antibacterial activity and UV-blocking ability for fabricating multi-functional textile products that can be utilized in a wide range of sustainable protective textiles, irrespective of the used post-finishing formulation ingredients. The results also show that both modification and functionalization processes are governed by the type of enzyme and kind of active material respectively. Moreover, the biosynthesized kerationlytic proteases could be accessibly used to remove protein-based stains like blood and egg.

Graphical abstract

     

Properties and microstructure of copper-alloyed solid solution-strengthened ductile iron

Solid solution-strengthened ductile iron (DI) exhibits outstanding mechanical properties due to the high silicon content. The strengthening by silicon addition is limited since additions above 4.3?wt-% lead to embrittlement. For a further improvement of mechanical properties, other alloying elements need to be considered. In the present work, the effect of various copper additions on the microstructure and the mechanical properties of solid solution-strengthened DI were investigated. The results show that no appreciable strengthening can be achieved by copper addition without the formation of pearlite in the matrix. The pearlite content increases considerably for Cu-additions above 0.23?wt-% and is independent of the cooling rate for the cooling conditions analysed.     

Determining parameters of heat exchangers for heat recovery in a Cu–Cl thermochemical hydrogen production cycle

A heat exchanger is a device built for efficient heat transfer from one medium to another. Shell and tube heat exchangers are separated wall heat exchangers and are commonly used in the nuclear and process industry. The CuCl cycle is used to thermally crack water in to H₂ and O₂. The present study presents the heat exchanger thermal design using analysis of variance for heat recovery from oxygen at 500 °C, coming from the molten salt reactor. Polynomial regressions in terms of the amount of chlorine in the oxygen, the mass flow rate on the tube side, and the shell's outlet temperature are estimated for various exchanger parameters and the results are compared with the bell Delaware method. Based on energy and exergy analysis, this study also discusses the best possible path for the recovered heat from oxygen. Optimal heat exchanger parameters are estimated by Design-Expert^® Stat-Ease for most effective heat recovery.     

Improved monarch butterfly optimization for unconstrained global search and neural network training

This work is a seminal attempt to address the drawbacks of the recently proposed monarch butterfly optimization (MBO) algorithm. This algorithm suffers from premature convergence, which makes it less suitable for solving real-world problems. The position updating of MBO is modified to involve previous solutions in addition to the best solution obtained thus far. To prove the efficiency of the Improved MBO (IMBO), a set of 23 well-known test functions is employed. The statistical results show that IMBO benefits from high local optima avoidance and fast convergence speed which helps this algorithm to outperform basic MBO and another recent variant of this algorithm called greedy strategy and self-adaptive crossover operator MBO (GCMBO). The results of the proposed algorithm are compared with nine other approaches in the literature for verification. The comparative analysis shows that IMBO provides very competitive results and tends to outperform current algorithms. To demonstrate the applicability of IMBO at solving challenging practical problems, it is also employed to train neural networks as well. The IMBO-based trainer is tested on 15 popular classification datasets obtained from the University of California at Irvine (UCI) Machine Learning Repository. The results are compared to a variety of techniques in the literature including the original MBO and GCMBO. It is observed that IMBO improves the learning of neural networks significantly, proving the merits of this algorithm for solving challenging problems.     

Motion planning algorithms for molecular simulations: A survey

Motion planning is a fundamental problem in robotics that has motivated research since more than three decades ago. A large variety of algorithms have been proposed to compute feasible motions of multi-body systems in constrained workspaces. In recent years, some of these algorithms have surpassed the frontiers of robotics, finding applications in other domains such as industrial manufacturing, computer animation and computational structural biology. This paper concerns the latter domain, providing a survey on motion planning algorithms applied to molecular modeling and simulation. Both the algorithmic and application sides are discussed, as well as the different issues to be taken into consideration when extending robot motion planning algorithms to deal with molecules. From an algorithmic perspective, the paper gives a general overview of the different extensions to sampling-based motion planners. From the point of view of applications, the survey deals with problems involving protein folding and conformational transitions, as well as protein–ligand interactions.     

Ontogeny of the testicular excurrent duct system of male Japanese quail (Coturnix japonica): A histological,ultrastructural, and histometric study

The testicular excurrent duct system undergoes several physiological and morphological changes during the reproductive stage or breeding season in mammals, birds, and reptiles. Studies on normal age-related histomorphological changes in the excurrent duct system of Japanese quails (Coturnix japonica) remain unreported, despite the extensive use of this bird as an avian model in research studies. The current study investigated the histological, ultrastructural, and histometric changes in the testicular excurrent duct system of the Japanese quail during three reproductive stages, namely prepubertal, pubertal, and adult. Simple squamous to low cuboidal cells formed the epithelia of the rete testis in prepubertal and pubertal birds, while in adult birds the lining was low cuboidal to cuboidal. In pubertal and adult birds, the nonciliated Type I epithelial cells of the proximal efferent duct displayed a subapical endocytotic apparatus comprising coated pits, coated apical tubules, and endosomes. There was a significant increase (p ≤ .001) in epithelial heights of all ducts of the excurrent duct system in the mature, sexually active, adult birds when compared to the other age groups. The luminal and tubular diameters, and the cross-sectional areas of efferent ducts and the epididymal duct unit increased significantly (p ≤ .001) with age. It is concluded that the morphology and morphometry of the excurrent ducts of the testis of the Japanese quail change as birds mature.     

Thermodynamics-antioxidant activity relationships of some 4-benzylidenamino-4, 5-dihydro-1h-1,2,4-triazol-5-one derivatives: Theoretical evaluation

Density functional methods were used to predict the antioxidative efficiency of thirteen 4-benzylidenamino-4, 5-dihydro-1H-1,2,4-triazol-5-one derivatives in the gas phase and in the solution phase (water and benzene). Optimized geometries of molecules and reaction thermodynamic energies (enthalpies and reaction-free energies) of three main antioxidant mechanisms (hydrogen atom transfer, single electron transfer-proton transfer, and sequential proton loss electron transfer) were studied at B3LYP/6-31G (d,p) level. Solvent contributions to thermodynamic energies were computed employing integral equation formalism integral equation formalism polarized continuum model method. Obtained results revealed that the three main working mechanisms were endothermic, but not spontaneous especially in the gas phase. We found that the single electron transfer process from the anionic form was more preferable than that from the neutral form in the gas phase. The comparison of the ionization potentials of 4-benzylidenamino-4, 5-dihydro-1H-1,2,4-triazol-5-one derivatives to those of classical antioxidants (gallic acid, caffeic acid, ferulic acid, and ascorbic acid) indicated that the electron transfer mechanism was more predominant in the thirteen 4-benzylidenamino-4, 5-dihydro-1H-1,2,4-triazol-5-one derivative compounds. Thermodynamically, single electron transfer process from the anionic form was the most preferable mechanism in the gas phase. Solvent effect drastically modified thermodynamic energies of mechanisms. The proton transfer process was the thermodynamically favored mechanism as compared to other mechanisms in both solvents. It is worth mentioning that all the mechanisms were found not to be spontaneous in the solution phase except the proton transfer process.