Removal of C.I. Basic Blue 41 from aqueous solution by supercritical water oxidation in continuous-flow reactor

Oxidation of aqueous solution of C.I. Basic Blue 41 (BB41), which is model azo dye pollutants, was studied in a continuous-flow reactor that was operated between 400 and 650 °C at a fixed pressure of 25 MPa. The total organic carbon (TOC) concentration of BB41 was in the range of 30.60 and 152.97 mmol/L in the feed stock solution. Hydrogen peroxide (H₂O₂) was used as an oxygen source and the oxidant concentrations were between 73.53 and 489.64 mmol/L in the feed stock solution. The results demonstrated that supercritical water oxidation (SCWO) process decreases the TOC up to 99.87% in very short reaction times (at residence times of 9–19 s). According to the wastewater and oxidant concentrations, the global rate expression was regressed from the complete set of data for each dye solution. As a result of regression analysis, the reaction rate expression for the oxidation of BB41 was determined with the activation energy of 18.88 (±0.9) kJ/mol and the pre-exponential factor of 2.8 (±0.5) mmol^?0.16 L^0.16 s^?1; and the reaction orders for BB41 (based on TOC) and the oxidant were 0.84 (±0.03) and 0.32 (±0.05) in a 95% confidence level.     

Fatigue behaviour of welded joints from magnesium alloy (AZ31) according to the local strain concept

In the present study, the results of fatigue tests with the magnesium alloy AZ31 (ISO‐MgAl3Zn1) in the material states base metal, heat affected zone and weld metal obtained under strain control at room temperature within a range from 2·10² to 5·10⁶ cycles are presented. The fatigue behaviour was characterized by the Coffin–Manson–Basquin equations and the stress – strain behaviour by the Ramberg–Osgood equation. The data can be used to assess welded magnesium joints according to the local strain concept.     

The prediction of fracture in brittle solids subjected to very short duration tensile stresses

The failure mechanism of brittle solids under very short duration tensile loading differs basically from that under prolonged tensile loads. Under static loading, or long stress pulses, the initiation and propagation of a single inherent flaw may lead to complete separation of the part. By contrast, if the loading is of very short duration, many cracks have to initiate and propagate so that they can link up and create a fracture surface during the loading period. A simple theory is proposed which relates the strength values observed under short duration stress pulses to the distribution of inherent flaws in the material. The prediction is shown to compare favorably with experimental results obtained by subjecting several types of rock to electron beams which produce stress pulses lasting from fractions of a microsecond to several microseconds.

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Résumé Le mécanisme de rupture d'un solide fragile soumis à une charge de traction de courte durée diffère fondamentalement de celui obtenu par une mise en charge prolongée. Pour une charge statique ou dans le cas des impulsions à contrainte prolongée, l'initiation de la propagation d'un simple défaut inhérent peut conduire à une séparation complète des parties. Par contraste, si la mise en charge est de courte durée, plusieurs microfissures s'initient et se propagent de telle façon qu'elles peuvent s'enchainer et créer une surface de rupture pendant la période de charge. Une théorie simple est proposée reliant les valeurs de la résistance observée pour des impulsions de contraintes de courte durée à la distribution des défauts inhérents dans le matériau. Une corrélation favorable est démontrée avec les résultats expérimentaux obtenus en soumettant divers types de roches à l'action de faisceaux d'électrons durant des fractions de microsecondes et jusqu'à plusieurs microsecondes.

     

Schwingfeste Auslegung von Schweiß‐ verbindungen aus der Magnesiumknetlegierung AZ31(ISO‐MgAl3Zn1) mit dem Konzept der fiktiven Ersatzradien von rf = 1,0 mm und 0,05 mm

Fatigue design of welded joints from the wrought magnesium alloy AZ31 (ISO‐MgAl3Zn1) by the local stress concept with the fictitious notch radius of r_f = 1.0 mm and 0.05 mm The investigations were carried out with three different types of MIG‐ and TIG‐welded magnesium joints of the alloy AZ31. The evaluation of the results showed that the local stress concept using the fictitious notch radius of r_f = 1.0 mm can be applied to magnesium welded joints from plates with thicknesses t ≥ 5 mm independently of the weld geometries (fully or partially penetrated butt welds, transversal stiffeners). Design curves are proposed for different stress ratios, i.e. R = ‐1 as well as 0 and 0.5, which allow the consideration of residual stresses as well as load induced mean stresses. The results permit also the suggestion of Δσ = 28 MPa as FAT‐value for the IIW‐Fatigue Design Recommendations. Further, the FAT‐value Δσ = 73 MPa for the fictitious radius of r_f = 0.05 mm to be applied to welded thin magnesium joints is derived, too. These FAT‐values are compared with already known data for steel and aluminium joints. A linear relationship between the FAT‐values and the Young’s modulus is determined.     

Gas phase reaction kinetics in boron fibre production

In the production of boron fibres using the chemical vapor deposition (CVD) technique, boron deposition and dichloroborane formation reactions occurs simultaneously. Boron deposition reaction occurs at the surface, whereas the formation of dichloroborane is the result of both gas phase and surface reactions. A continuous stirred tank reactor (CSTR) type of reactor was designed to investigate the reaction kinetics and kinetic parameters in the gas phase reactions of boron trichloride and hydrogen. It was concluded that reaction rate of the product increased with an increase in the inlet concentration of both reactants (BCl₃ and H₂) and with an increase in the reactor temperature. While reaction order with respect to BCl₃ was almost constant at about 0.5 at each temperature, reaction order with respect to hydrogen increased significantly at temperatures lower than 350°C. A general rate expression was derived for BHCl₂ formation from BCl₃ and hydrogen. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Experimental investigation of the cooling performance of a ground source heat pump system in Denizli, Turkey

The ground source heat pump system (GSHP) is installed at PamukkaleUniversity in Denizli, Turkey. The U-bend ground heat exchanger pipe length of 225 m was buried in soil at 110 m depth. In the 2008 cooling season, performance coefficients of the heat pump and the system were determined in the range of 3.1-4.8 and 2.1-3.1, respectively. The values of solar radiation, external temperature, relative humidity and wind speed were measured continuously. The relations of performance coefficients of ground source heat pump according to the meteorological data including solar radiation, wind speed, relative humidity and external temperature with this experiment were revealed exactly. The results of this study fulfil the lack in the literature.     

A Correlation Study for the Positional Dependence of Friction Factor in Dilute Phase Flows

Results of a comprehensive study on the flow friction factor data collected on suspensions of solid granular particles of semolina, fly ash, and alumina having a size range of 75.5?µm ≤ d_p ≤ 275?µm in air are presented. The experimental study was composed of 250 separate test cases in which airflow Reynolds number Re = UD/ν and loading ratio M_p/M_a were varied systematically covering the ranges of 50,000 ≤ Re ≤ 100,000 and 5% ≤ M_p/M_a ≤ 25%. An upward flow field with variable inclinations α of 10°, 20°, and 30° with the horizontal plane and a horizontal flow field, i.e, 0° inclination, were used to determine the influence of gravitational forces. Local static pressure gradients measured along the flow field with distance x were used to determine local air-particle friction factor f_{p + a}, which was observed to be under the influence of particle type, M_p/M_a, Re, and flow line inclination, α. The proposed correlation for the variation of f_{p + a} with x/D was evaluated to reach a generalized form exhibiting interactive influence of Re, M_p/M_a?, α, and particle type.     

Sensorless control application of PMSM with a novel adaptation mechanism

Neural Computing and Applications - In this paper, we consider the challenging problem of finding shared information in multiple data streams simultaneously. The standard statistical method for...     

Fatigue strength estimation of butt welded joints in magnesium AZ31 alloy using the genetic algorithm

Genetic Algorithm is applied to calculate the substitute structural length (SSL) and obtain the fatigue strength of welded joints in magnesium. Fatigue tests with unnotched and notched specimens of the base material metal (BM), the weld metal (WM) and the heat‐affected zone (HAZ) of magnesium AZ31 (MgAl3) were carried out in order to derive the unknown substitute structural length. Results of fatigue tests with geometrically similar welded joints with full and partial penetration were available. The comparison of the experimental and predicted substitute structural length using Genetic Algorithm Substitute Structural Length Estimation Model (GASLEM) shows that the developed models seem to be capable of predicting the SSL values. Fatigue strength values were also obtained using predicted SSL.