An experimental study on the effect of gas injection configuration on flow characteristics in high viscosity oil columns

Gas-viscous liquid bubbly and slug flow are very common in petroleum, chemical, bioengineering, polymer, and food processing. However, there is a major knowledge gap in two-phase flow research in the design of gas injectors/distributers in very high viscosity oil systems. The present study investigates the effect of gas injection methods in columns containing very high viscosity oils (i.e., realistic liquids), and more specifically using 360 Pa · s viscosity oil in a 240-mm diameter column. The effects that the radial positioning, number of gas nozzles, and their distance from each other have on the structure of the flow in viscous liquids are presented in detail. Electrical capacitance tomography (ECT) is used to extract experimental data. Void fraction, bubble velocity, frequency, liquid film thickness, and bubble length were measured and analyzed at different radial gas injection positions. It has been observed that bubble length increases significantly by 0.3 m when the injection nozzle is located next to the wall of the pipe. Bubble velocity and length also increase by 0.217 m/s and 3.6 m, respectively, with increasing gas flowrate when multiple injection points are used. Increasing the distance between the gas injection points increased bubbles' length by 1.2 m. Bubbles' velocity and frequency (at higher gas flow rate) were also increased

Small bubbles formation and contribution to the overall gas holdup in large diameter columns of very high viscosity oil

A limited number of studies are available in literature on the small bubbles which create from gas-very high viscosity oils interaction and its contribution to the gas holdup in the system. The rate of small bubble formation has an important impact on heat and mass transfer in many chemical and industrial processes. The work presented in the current paper provides unique information on the formation of bubbles of millimetre diameter in high viscosity oil. A column of 290 mm diameter and Silicon oil of 330 Pa.s viscosity, were employed besides Electrical Capacitance Tomography and a high-resolution camera to investigate the characteristics of the small bubbles. Mechanism of bubble generation, effect of gas injection time and flowrate were studied. The average void fraction, total gas-liquid height, overall Probability Density Function (PDF) profile, small bubbles volume fractions and diameter were measured. Small bubbles generate from the eruption of large bubbles, at gas injection nozzles, coalescence of large bubbles, and at liquid bridges at transition to churn flow regime. Properties and concentration of the small bubbles are controlled by the location of the bubble generation, gas flowrate, and gas injection time. Small bubbles contribute by 6.6- 30% to the total gas holdup. Bubble diameter increased from 0.68 mm to 0.75 mm and decreased from 1.1 mm to 0.75 mm at the top and the bottom sections of the column respectively after 60 minof gas injection

Dynamics of flow transitions from bubbly to churn flow in high viscosity oils and large diameter columns

The dynamic behaviour of the gas-liquid two phase flows and in particular the flow pattern stability and transition between the flow regimes are influenced significantly by both the properties of the liquid and gas as well as the pipe diameter. The majority of the studies reported in the literature on the dynamics of gas-liquid flow transitions focus only on low viscosity liquids (e.g. water) and small diameter pipes. In the present work a series of experiments were carried out to study the dynamics of flow transitions (bubbly to slug and slug to churn) of gas rising through very viscous oils (330 Pa s and 360 Pa s) in two large diameter columns (290 and 240 mm, respectively), using Electrical Capacitance Tomography (ECT) and pressure sensors. The experiments aimed to imitate a number of realistic flow conditions that might be encountered, for examples, in; bitumen, crude oil, viscous liquids in food processing and volcanic magmatic flows. Observation and quantification of bubbly to slug and slug to churn flow transitions for gas-high viscous liquids in large pipe diameters are presented for the first time. Flow parameters and characteristics including; void fraction, pressure gradient, Probability Density Function, structure velocity, lengths of large/Taylor bubbles and liquid slugs and the effect of liquid temperature on the void fraction and Taylor bubble lengths, were measured and analysed. It was found that transition to slug and churn flow occurs gradually. Transition to slug flow occurs at a gas superficial velocity of 0.011 m/s–0.016 m/s, while transition to churn appears in the range of 0.127–0.243 m/s in both columns

An Oxalate Bridged Binuclear Iron(III) Ionic Liquid for the Highly Efficient Glycolysis of Polyethylene Terephthalate under Microwave Irradiation

An oxalate-bridged binuclear iron(III) ionic liquid combined with an imidazolium based cation, (dimim)2[Fe2Cl4(µ-ox)], was synthesized and characterized by a wide range of techniques. This halometallate ionic liquid was active in catalyzing the depolymerization of polyethylene terephthalate (PET) by glycolysis, under conventional and microwave-assisted heating conditions. Both methodologies were very selective towards the production of bis(2-hydroxyethyl)terephthalate (BHET). The employment of microwave heating proved beneficial in terms of time and energy saving when compared to the use of thermal heating. Indeed, dielectric spectroscopy studies revealed that the binuclear iron-containing ionic liquid exhibits an excellent heating response under an electromagnetic field. The catalyst provided quantitative conversions to BHET in the glycolysis of post-consumer PET bottles in only 3 h through microwave heating, as compared to 80 % conversion after 24 h under conventional heating

Quantum gate algorithm for reference-guided DNA sequence alignment

Reference-guided DNA sequencing and alignment is an important process in computational molecular biology. The amount of DNA data grows very fast, and many new genomes are waiting to be sequenced while millions of private genomes need to be re-sequenced. Each human genome has 3.2 B base pairs, and each one could be stored with 2 bits of information, so one human genome would take 6.4 B bits or about 760 MB of storage (National Institute of General Medical Sciences). Today most powerful tensor processing units cannot handle the volume of DNA data necessitating a major leap in computing power. It is, therefore, important to investigate the usefulness of quantum computers in genomic data analysis, especially in DNA sequence alignment. Quantum computers are expected to be involved in DNA sequencing, initially as parts of classical systems, acting as quantum accelerators. The number of available qubits is increasing annually, and future quantum computers could conduct DNA sequencing, taking the place of classical computing systems. We present a novel quantum algorithm for reference-guided DNA sequence alignment modeled with gate-based quantum computing. The algorithm is scalable, can be integrated into existing classical DNA sequencing systems and is intentionally structured to limit computational errors. The quantum algorithm has been tested using the quantum processing units and simulators provided by IBM Quantum, and its correctness has been confirmed.Comment: 19 pages, 13 figure

Traceable measurement and imaging of the complex permittivity of a multiphase mineral specimen at micron scales using a microwave microscope

This paper describes traceable measurements of the dielectric permittivity and loss tangent of a multiphase material (particulate rock set in epoxy) at micron scales using a resonant Near-Field Scanning Microwave Microscope (NSMM) at 1.2 GHz. Calibration and extraction of the permittivity and loss tangent is via an image charge analysis which has been modified by the use of the complex frequency to make it applicable for high loss materials. The results presented are obtained using a spherical probe tip, 0.1 mm in diameter, and also a conical probe tip with a rounded end 0.01 mm in diameter, which allows imaging with higher resolution (≈10 µm). The microscope is calibrated using approach-curve data over a restricted range of gaps (typically between 1% and 10% of tip diameter) as this is found to give the best measurement accuracy. For both tips the uncertainty of scanned measurements of permittivity is estimated to be±10% (at coverage factor k=2) for permittivity ⪝10. Loss tangent can be resolved to approximately 0.001. Subject to this limit, the uncertainty of loss tangent measurements is estimated to be±20% (at k=2). The reported measurements inform studies of how microwave energy interacts with multiphase materials containing microwave absorbent phases

The ANZUS Treaty during the Cold War: a reinterpretation of U.S. diplomacy in the Southwest Pacific

This article explains the origins of the Australia–New Zealand–United States (ANZUS) Treaty by highlighting U.S. ambitions in the Pacific region after World War II. Three clarifications to the historiography merit attention. First, an alliance with Australia and New Zealand reflected the pursuit of U.S. interests rather than the skill of antipodean diplomacy. Despite initial reservations in Washington, geostrategic anxiety and economic ambition ultimately spurred cooperation. The U.S. government's eventual recourse to coercive diplomacy against the other ANZUS members, and the exclusion of Britain from the alliance, substantiate claims of self-interest. Second, the historiography neglects the economic rationale underlying the U.S. commitment to Pacific security. Regional cooperation ensured the revival of Japan, the avoidance of discriminatory trade policies, and the stability of the Bretton Woods monetary system. Third, scholars have unduly played down and misunderstood the concept of race. U.S. foreign policy elites invoked ideas about a “White Man's Club” in Asia to obscure the pursuit of U.S. interests in the region and to ensure British exclusion from the treaty

Churn flow in high viscosity oils and large diameter columns

Churn flow is an important intermediate flow regimoccurring in between slug and annular flow patterns in two-phase flow, with profound implications in chemical and petroleum industry. The majority of studies to date in churn flow has been carried out mainly using water or liquids of low viscosities and limited information exists regarding the behaviour of high viscosity liquids which resemble realistic process conditions. In this paper, a study that investigated churn flow and its characteristics in high viscosity oils (360 and 330 Pa.s) and large diameter columns (240 and 290mm) is presented for a first time. Transition to churn flow regime starts when the structure velocity, length and frequency of the liquid bridges, which appear at the end of slug flow, increase. In churn flow, gas flows at the core of the oil column with a wavy passage, leaving the top surface open to atmosphere with a possibility of creating a very long bubble. The average length of the bubbles seen to decrease with increasing the gas flow rate. While, no considerable change is observed in void fraction, structure velocity and film thickness at this flow pattern