Capturing the Dynamics of Foam Coarsening in a HPHT Microfluidic System

The foam coarsening process is significant to foam stability in porous media. This study provides, for the first time, direct visualization of the foam coarsening process in porous media under realistic reservoir conditions. Foam coarsening behavior in porous media has shown a similar linear increase in the average bubble area to that in an open system but differs in two stages. The average bubble area increases with a faster rate in stage 1 and then increases with a slower rate in stage 2 and stage 2 dominates the foam coarsening process. The transition between the two stages occurs as the inner bubbles disappear when the edge bubbles start feeling the effects of the walls. The foam at steady-state shows a bimodal size distribution with bubbles trapped in the pore bodies and pore throats. The effects of pore pressure (600-3200 psi) and temperature (22-100 °C) were studied. Foam coarsening dynamics are sensitive to pore pressure and temperature, where higher pore pressure and lower temperature are more favorable to maintain a stable foam. Finally, the coarsening rates of foams generated with different gas phases were compared. In contrast to N2 foam and gas CO2 foam, supercritical CO2 foam exhibits the slowest coarsening rate because of its ultralow interfacial tension.

Role of Magnetic Fields in Ram Pressure Stripped Galaxies

Ram-pressure stripping is a crucial evolutionary driver for cluster galaxies and jellyfish galaxies characterized by very extended tails of stripped gas, and they are the most striking examples of it in action. Recently, those extended tails are found to show ongoing star formation, raising the question of how the stripped, cold gas can survive long enough to form new stars outside the stellar disk. In this study, we summarize the most recent results achieved within the GASP collaboration to provide a holistic explanation for this phenomenon. We focus on two textbook examples of jellyfish galaxies, JO206 and JW100, for which, via multi-wavelength observations from radio to X-ray and numerical simulations, we have explored the different gas phases (neutral, molecular, diffuse-ionized, and hot). Based on additional multi-phase gas studies, we now propose a scenario of stripped tail evolution including all phases that are driven by a magnetic draping sheath, where the intracluster turbulent magnetized plasma condenses onto the galaxy disk and tail and produces a magnetized interface that protects the stripped galaxy tail gas from evaporation. In such a scenario, the accreted environmental plasma can cool down and eventually join the tail gas, hence providing additional gas to form stars. The implications of our findings can shed light on the more general scenario of draping, condensation, and cooling of hot gas surrounding cold clouds that is fundamental in many astrophysical phenomena.

Copper(II) Perfluorinated Carboxylate Complexes with Small Aliphatic Amines as Universal Precursors for Nanomaterial Fabrication

Copper(II) carboxylate compounds with ethylamine and isopropylamine of the general formula [Cu2(RNH2)2(µ-O2CRf)4], where R = Et, iPr, and Rf = CnF2n+1, n = 1–6, were characterised in the condensed and gas phases by electron impact mass spectrometry (EI MS), IR spectroscopy, and thermal analysis. A mass spectra analysis confirmed the presence of metallated species in the gas phase. Among the observed fragments, the pseudomolecular ions [Cu2(RNH2)2(µ-O2CRf)3]+ were found, which suggests the dimeric structure of the studied complexes with axially N-coordinated ethyl- or isopropylamine molecules and bridging perfluorinated carboxylates. TGA studies demonstrated that copper transfer to the gas phase occurs even under atmospheric pressure. The temperature range of the [Cu2(RNH2)2(µ-O2CRf)4] and other copper carriers detection, observed in variable temperature infrared spectra, depends on the type of amine. The possible mechanisms of the decomposition of the tested compounds are proposed. The copper films were produced without additional reducing agents despite using Cu(II) CVD precursors in the chemical vapor deposition experiments. The layers of the gel-like complexes were fabricated in both spin- and dip-coating experiments, resulting in copper or copper oxide materials when heated. Dinuclear copper(II) carboxylate complexes with ethyl- and isopropylamine [Cu2(RNH2)2(µ-O2CRf)4] can be applied for the formation of metal or metal oxide materials, also in the nanoscale, by vapour and ‘wet’ deposition methods.

Spin-Up from Rest of a Liquid Metal with Deformable Free Surface in a Cylinder under the Influence of a Uniform Axial Magnetic Field

Spin-up from rest of a liquid metal having deformable free surface in the presence of a uniform axial magnetic field is numerically studied. Both liquid and gas phases in a vertically mounted cylinder are assumed to be an incompressible, immiscible, Newtonian fluid. Since the viscous dissipation and the Joule heating are neglected, thermal convection due to buoyancy and thermocapillary effects is not taken into account. The effects of Ekman number and Hartmann number were computed with fixing the Froude number of 1.5, the density ratio of 800, and the viscosity ratio of 50. The evolutions of the free surface, three-component velocity field, and electric current density are portrayed using the level-set method and HSMAC method. When a uniform axial magnetic field is imposed, the azimuthal momentum is transferred from the rotating bottom wall to the core region directly through the Hartmann layer. This is the most striking difference from spin-up of the nonmagnetic case.

Experimental study of wavy-annular flow in a rectangular microchannel using LIF method

This article aims at studying gas-liquid flow in a rectangular microchannel with a high aspect ratio (200 × 2045 μm). Liquid and gas phases were 95% ethanol and nitrogen mixture. Experimental flow characteristics are obtained using high-speed visualization and laser-induced fluorescence (LIF) methods. Using the LIF method for wavy-annular flow, the average film thickness, liquid film distribution, and liquid film width were measured. The dependences of the liquid film width and the average film thickness on gas superficial velocity are presented in graphical form and analyzed. An increase in gas superficial velocity causes growth of the liquid film width and thickness of the liquid film, which indicates the process of liquid transfer from the menisci area to the liquid film. For different liquid velocities and the same gas superficial velocities, close values of averaged liquid film thickness were observed for flow with 2D waves and 3D waves on liquid film.

Massive Molecular Outflow and 100 kpc Extended Cold Halo Gas in the Enormous Lyα Nebula of QSO 1228+3128

The link between the circumgalactic medium (CGM) and the stellar growth of massive galaxies at high-z depends on the properties of the widespread cold molecular gas. As part of the SUPERCOLD-CGM survey (Survey of Protocluster ELANe Revealing CO/[C i] in the Lyα-Detected CGM), we present the radio-loud QSO Q1228+3128 at z = 2.2218, which is embedded in an enormous Lyα nebula. ALMA+ACA observations of CO(4–3) reveal both a massive molecular outflow, and a more extended molecular gas reservoir across ∼100 kpc in the CGM, each containing a mass of M H2 ∼ 4–5 × 1010 M ⊙. The outflow and molecular CGM are aligned spatially, along the direction of an inner radio jet. After reanalysis of Lyα data of Q1228+3128 from the Keck Cosmic Web Imager, we found that the velocity of the extended CO agrees with the redshift derived from the Lyα nebula and the bulk velocity of the massive outflow. We propose a scenario where the radio source in Q1228+3128 is driving the molecular outflow and perhaps also enriching or cooling the CGM. In addition, we found that the extended CO emission is nearly perpendicular to the extended Lyα nebula spatially, indicating that the two gas phases are not well mixed, and possibly even represent different phenomena (e.g., outflow versus infall). Our results provide crucial evidence in support of predicted baryonic recycling processes that drive the early evolution of massive galaxies.

Hydrocarbon Retention and the Case for Vertical Migration

Complex hydrocarbon charging and distribution in which reservoirs are filled by oil and gas phases with different densities and genetic types inter-fingering within the basin, are common phenomena, and often attributed to vertical migration. This paper discusses the factors that control vertical hydrocarbon migration and presents modelling of the hydrocarbon charging and entrapment history in a tertiary basin in Southeast Asia as a case study. According to the Young-Laplace flow theory of the secondary hydrocarbon migration mechanics, migration occurs in a state of capillary equilibrium in a flow regime dominated by buoyancy and capillary forces. In this study, the invasion percolation simulation algorithm, based on the Young-Laplace flow, was used. During the simulation, three-dimensional (3D) seismic data were used as the high-resolution base grid for migration to capture the effect of both structure and facies heterogeneities on fluid flow. A model of an unfaulted system was presented to make the case. In the study area there is inter-fingering between oil and gas across different formations; most oils are trapped in the deeper formation, oil and gas inter-fingering occurs in the middle formation, and the upper formation contains mostly gas. This arrangement is possible because of the interplay between the expelled fluid buoyancy and relatively weak intra-formational seals within the basin. The modeling results were then calibrated to known accumulations or fluid presence in wells. In a basin dominated by a vertical migration regime, hydrocarbons are prevented from travelling far from the kitchen, thus decreasing prospectivity away from the kitchen. Through a case study, this paper helps to understand the factors that influence hydrocarbon retention and migration that control fluid distribution within a basin. Eventually the study helps geologists to understand prospectivity risking related to hydrocarbon charging, which is one of the main risks in exploration especially in mature basins.

Preparation and Characterization of Metal Membranes for Gas Separation

The purpose of this article is the characterization of permeability and the ideal selectivity of new metallic brass membranes with a “sandwich” structure. Characterization is an important factor related to the morphology, structure, and properties of the membrane. The membranes were examined for simple gas phases, including various exogenous factors on their performance (temperature, pressure, durability). To evaluate their performance, permeate measurements were made at temperatures from -18 to 300°C and at various pressures from 1 to 10 bar. Results have shown that permeability is influenced by the molecular weight and exhibits ideal selectivity greater or equal by Knudsen’s ideal separation factor in a sequence of Η2>He>CH4>N2>O2>Ar≥CO2. The permeability is also a function of the thickness of the membrane, as it shows there’s a decrease in permeability and an increase in selectivity when the thickness is increased. The effect of temperature on these metal membranes is considered an important factor in the operation of membranes and membrane systems. The main feature is the reduction of permeability with the increase of temperature.

Similarity model for predicting the performance of an R718 compressor

A general compression refrigeration system consists of a compressor, condenser, pressure-reducing valve, and evaporator to induce phase changes in the refrigerant. The performance of the compression refrigeration system strongly depends on the type and characteristics of the refrigerant. However, synthetic refrigerants such as chlorofluorocarbon, hydrochloro-fluorocarbon, and hydrofluorocarbon directly affect the environment as greenhouse gases and indirectly affect the environment by generating substances as they decompose. Thus, researchers have been focusing on developing refrigerants with a low or zero global warming potential. R718 (i.e. water) is an ecofriendly refrigerant, but its specific volume rapidly changes between the liquid and gas phases. This requires making the components of the compression refrigeration system larger than normal to accommodate these volume changes, which is inefficient for manufacturing prototypes. In this study, an alternative refrigerant was applied to the design of a centrifugal compressor that uses R718 as the working fluid. To address the volume change of R718, a numerical analysis was conducted by using the similarity method, where the size of the impeller was reduced and the rotational speed was controlled. To ensure the reliability of the similarity model, its results were compared against the experimental data of the original model for verification.

Pengaruh Fraksi Berat Serbuk Alumina Terhadap Porositas Busa Aluminium Hasil Injeksi Gas

Aluminum foam is a very interesting material to develop. This material is a material that has a combination of characteristics between physical and mechanical properties such as high stiffness and low density. There are several processes for making aluminum foam that have been developed, either through the liquid, solid, or gas phases. And of these various processes, the process of making aluminum foam through the liquid phase by using the gas injection method is the simplest and cheapest process. The principle of the process of making aluminum foam with this method is that bubbles are produced from the process of blowing the gas into the aluminum liquid in which there are additive particles that function as a bubble stabilizer. These stable bubbles will become pores after the aluminum liquid solidifies. This research will discuss the effect of the weight fraction of alumina powder with an average size of 5.77 μm added to liquid aluminum on the macro-pore structure in the form of shape and size as well as the spread of the resulting pores. And the result is that the optimal weight fraction of adding alumina powder is 15%, where the resulting pores have a more homogeneous and evenly shaped and sized.