Effect of warm mix additives on the interfacial bonding characteristics of asphalt binders

The quality of the interfacial bonding between asphalt binder and aggregates plays a significant role in determining the durability of asphalt mixtures. Warm mix asphalt (WMA) modifiers have been used extensively in the last decade primarily to reduce production and compaction temperatures as well as to improve workability of asphalt mixtures. This study aimed to provide better understanding of the effects of these WMA modifiers on the interfacial bonding between asphalt binders and aggregates. The evaluation focused on measuring surface energy of binders in unaged and aged states and aggregates and then calculating energy parameters that describe the potential of a given asphalt-aggregate combination to resist fatigue cracking and moisture damage. Results show that the combination of asphalt-WMA additive, as well as the content applied of WMA additive has a significant impact on the fatigue cracking and moisture damage resistance. The results suggest that it is poor practice to use a given type and percentage of WMA modifier without regard for binder type. Instead, test methods are recommended to evaluate the compatibility of asphalt binder, WMA additive type/content, and aggregates for improved performance at different conditions.     

Carbon dioxide absorption by ammonia intensified with membrane contactors

Membrane gas absorption technology is a promising alternative for CO₂ removal from post-combustion coal-fired flue gases. This study examines an alternative which consists in absorbing carbon dioxide by ammonia aqueous solution in a membrane contactor to improve the capture processes and to intensify the gas–liquid transfer. Absorption measurements through a membrane contactor have been made. The influence of the material nature constituting the membrane and operating parameters on the capture efficiency has been studied. The potentialities of dense skin membrane contactors are discussed with regard to both increased CO₂ mass transfer performances and mitigation of ammonia volatilization. The results have shown that it is possible to capture CO₂ from ammonia through a membrane with capture efficiency greater than 90 %. The membrane limits ammonia losses but does not eliminate it. The experimental results are used to calculate an intensification factor of 5, which represents the comparison between the membrane overall absorption rate to that of the column.     

3D line-support grid flattening for more accurate geostatistical reservoir population with petrophysical properties

Reservoir models are essential if we need to clearly understand the fossil resources and, hence, to make better use of them. Feeding these models with physical properties on the basis of wells data is a key step in their construction. Line-support (LS) grid is the most popular grid in reservoir engineering, it is massively used for reservoir simulations. In the current methods used to populate with properties the LS grid of a reservoir unit, a Cartesian grid of equivalent size (in each direction), obtained by averaging the edge lengths, is first of all completed. The properties calculated in this way are then transferred as they are into the initial LS grid, because there is cell-for-cell correspondence. This leads to distortion of the Cartesian grid, making it fit the shape of the LS grid. This has the effect of altering calculations of correlation distances between well markers in geostatistical population simulations. Consequently, this primarily induces distortions on the simulated bodies. To resolve this problem, in this paper, we propose innovative methods for a “smooth” conversion from the LS grid of the structural space to the Cartesian grid of the geostatistical population space. The basic principle is to calculate the correlation distances between wells on the basis of “quasi-isometric” flattening of the stratigraphic unit LS grid in the population space. This same flattening technique is then used for inverse transfer of the properties from the population space to the structural space.     

Parametric study of an efficient renewable power-to-substitute-natural-gas process including high-temperature steam electrolysis

Power-to-Substitute Natural Gas processes are investigated to offer solutions for renewable energy storing or transportation. In the present study, an original Power-to-SNG process combining high-temperature steam electrolysis and CO₂ methanation is implemented and simulated. A reference process is firstly defined, including a specific modelling approach of the electrolysis and a methanation modelling including a kinetic law. The process also integrates a unit to clean the gas from residual CO₂, H₂ and H₂O for gas network injection. Having set all the units, simulations are performed with ProsimPlus 3™ software for a reference case where the electrolyser and the methanation reactors are designed. The reference case allows to produce 67.5 Nm³/h of SNG with an electrical energy consumption of 14.4 kW h/Nm³. The produced SNG satisfies specifications required for network injection. From this reference process, two sensitivity analyses on electrolysis and methanation working points and on external parameters and constraints are considered. As a main result, we observe that the reference case maximises both process efficiency and SNG production when compared with other studied cases.     

Intrinsic second-order nonlinearity in chalcogenide glasses containing HgI2

Frequency conversion using nonlinear optical (NLO) crystals is widely used in advanced photonic technologies to produce coherent light in the spectral regions where the available laser sources are missing. Isotropic glasses usually do not show second order nonlinear processes like second harmonic or difference frequency generation (SHG, DFG) except for temporarily induced anisotropy under external stimuli. Here, we show that a HgI₂–Ga₂S₃–GeS₂ homogeneous glass exhibits a strong intrinsic SHG response comparable with that of the well-known NLO single crystal LiNbO₃. The origin of this extremely rare phenomenon seems to be noncentrosymmetric bent HgI₂ molecules embedded in a sulfide glassy host. Taking into account the unique properties of chalcogenide glasses (wide IR transmission, low phonon density, unlimited ability to be modified changing the appropriate glass properties, fiber drawing and thin layer design), the observed phenomenon opens up the possibility of creating fundamentally new devices for mid-IR photonics.     

Photochemische Primärprozesse von Xanthenfarbstoffen. I. Blitzlichtspektroskopische Untersuchung der Primärprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. I. Investigations of the Primary Processes of Selenopyronine by Flash Excitation The triplet-state of selenopyronine absorbs light in the whole investigated spectral range (λ_max = 400 nm, 480 nm, 690 nm). As results of the bimolecular triplet decay a half-reduced (λ_max = 430 nm) and a half-oxidized (λ_max = 475 nm) form of the dye are observed. p-Benzoquinone quenches the triplet-state (k₇ = 1,5 · 10⁹ l/mol s) and the results are the half-oxidized form and the p-benzosemiquinone ion. For these two products different decay processes exist. The reducing agents DABCO, EDTA and Hydroquinone also quench the triplet state (k₁₀ = 1,2 · 10⁶ l/mol s, k₁₁ = 1,0 · 10⁶ l/mol s, k₁₂ = 1,0 · 10⁹ l/mol s) and as result the half-reduced form is observed. Measurements with thiopyronine give analogous results, which are in good agreement with investigations published in the literature.     

Photochemische Primärprozesse von Xanthenfarbstoffen. III. Blitzlichtspektroskopische Untersuchungen zum Einfluß von kationischen Mizellen auf die Photoredoxprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. III. Investigations of the Influence of Cationic Micelles on the Photoredox Processes of Selenopyronine by Flash Excitation Cationic micelles have no influence on the decay of the triplet state of selenopyronine (³F⁺). The products of photoredox reactions ³F⁺ + ³F⁺ (F⁺) → F^· + F and ³F⁺ + DABCO → F^· + DABCO live longer in the presence of the cationic micelles. The reason for the change of the lifetime is a separation of the photoredox products by micelles. F^. is stored in the interior of the micelles. The positively charged F and DABCO are repelled from the micelles and the electron back transfer is hindered.     

Photochemische Primärprozesse von Xanthenfarbstoffen. II. Blitzlichtspektroskopische Untersuchungen zum Einfluß von anionischen Mizellen auf die photochemischen Primärprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. II. Investigations of the Influence of Anionic Micelles on the Primary Processes of Selenopyronine by Flash Excitation In aqueous solutions containing anionic micelles, the dye cations of selenopyronine are present at the micellar surface. If the concentration of the dye ions is much lower than the concentration of micelles, only monomolecular triplet decay (k₁^aM = 2 · 10⁻³s⁻¹) is observed. Under these conditions, the half-oxidized and half-reduced form of selenopyronin is not formed. If the concentration of the dye ions is much higher than the concentration of micelles, two or more dye ions are present at every micelle, and a fast bimolecular decay of the triplet state during the flash is observed. The quenching of the triplet state with p-benzoquinone (k₇^aM = 1,9 · 10⁹ l/mol s), DABCO (k₁₀^aM = 1,6 · 10⁷ l/mol s) and EDTA (k₁₁^aM = 1,3 · 10⁵ l/mol s) and the decay processes of the half-reduced and half-oxidized form in the micellar solution are investigated.     

Computations of shear driven vortex flow in a cylindrical cavity using a modified k-ε turbulence model

In this paper, a new variant of the k-ε turbulence model (Saqr et al., CFD Letters, 1(2) pp. 87–94) is used to compute the shear driven vortex flow in an open cylindrical cavity. The results are compared with published LDA measurements for such flow configuration. The modified turbulence model demonstrated good agreement with experimental results, which further supports its validity in computing vortex dominated flows.