scholarly journals Morphology Investigation on Cyclopentane Hydrate Formation/Dissociation in a Sub-Millimeter-Sized Capillary

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 307
Author(s):  
Qiang Sun ◽  
Mei Du ◽  
Xingxun Li ◽  
Xuqiang Guo ◽  
Lanying Yang
Keyword(s):  
Growth Rate ◽  
Memory Effect ◽  
Significant Influence ◽  
Driving Force ◽  
Hydrate Formation ◽  
Formation Temperature ◽  
Water Interface ◽  
Supercooling Degree ◽  
Three Phase ◽  
Formation Driving

The formation, dissociation, and reformation of cyclopentane (CP) hydrate in a sub-millimeter-sized capillary were conducted in this work, and the morphology of CP hydrate was obtained during above processes, respectively. The influences of the supercooling degree, i.e., the hydrate formation driving force, on CP hydrate crystals’ aspect and growth rate were also investigated. The results demonstrate that CP forms hydrate with the water melting from ice at the interface between the CP and melting water at a temperature slightly above 273.15 K. With the action of hydrate memory effect, the CP hydrate in the capillary starts forming at the CP-water interface or CP–water–capillary three-phase junction and grows around the CP–water interface. The appearance and growth rate of CP hydrate are greatly influenced by the supercooling degree. It indicates that CP hydrate has a high aggregation degree and good regularity at a high supercooling degree (or a low formation temperature). The growth rate of CP hydrate crystals greatly increases with the supercooling degree. Consequently, the temperature has a significant influence on the formation of CP hydrate in the capillary. That means the features of CP hydrate crystals in a quiescent system could be determined and controlled by the temperature setting.

scholarly journals Carbon Isotope Fractionation during the Formation of CO2 Hydrate and Equilibrium Pressures of 12CO2 and 13CO2 Hydrates

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4215
Author(s):  
Hiromi Kimura ◽  
Go Fuseya ◽  
Satoshi Takeya ◽  
Akihiro Hachikubo
Keyword(s):  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Small Difference ◽  
Hydrate Formation ◽  
Formation Temperature ◽  
Carbon Isotope Fractionation ◽  
Unit Cell Size ◽  
Naturally Occurring ◽  
Three Phase ◽  
The Difference

Knowledge of carbon isotope fractionation is needed in order to discuss the formation and dissociation of naturally occurring CO2 hydrates. We investigated carbon isotope fractionation during CO2 hydrate formation and measured the three-phase equilibria of 12CO2–H2O and 13CO2–H2O systems. From a crystal structure viewpoint, the difference in the Raman spectra of hydrate-bound 12CO2 and 13CO2 was revealed, although their unit cell size was similar. The δ13C of hydrate-bound CO2 was lower than that of the residual CO2 (1.0–1.5‰) in a formation temperature ranging between 226 K and 278 K. The results show that the small difference between equilibrium pressures of ~0.01 MPa in 12CO2 and 13CO2 hydrates causes carbon isotope fractionation of ~1‰. However, the difference between equilibrium pressures in the 12CO2–H2O and 13CO2–H2O systems was smaller than the standard uncertainties of measurement; more accurate pressure measurement is required for quantitative discussion.

Research Progress on the Driving Force of Gas Hydrate Formation

2012 ◽  
Vol 616-618 ◽  
pp. 902-906 ◽  
Author(s):  
Chun Long Wang ◽  
Xue Min Zhang ◽  
Jin Ping Li ◽  
Lin Jun Wang ◽  
Liang Jiao
Keyword(s):  
Growth Rate ◽  
Gas Hydrate ◽  
Induction Time ◽  
Driving Force ◽  
Hydrate Formation ◽  
Research Direction ◽  
Research Progress ◽  
Force Model ◽  
Hydration Reaction ◽  
Gas Hydrate Formation

Predicting the driving force accurately is the key process to hydrate nucleating and growing of hydration reaction. The nucleating and growing process of hydrate is relevant to temperature, pressure and component of reactant, and the property of reaction tank and intermiscibility of reactant have notable effect on the formation process of hydrate with its nucleating position, the induction time, growth rate and hydration rate. However, the present driving force model of hydrate cannot predict nucleating area, induction time, growth rate and the reaction limit, and also can't explain the influence of some factors such as cooling rate, temperature disturbance and inlet way on the hydration reaction, it is uncertain of the process to gas hydrate nucleation. We introduced some driving force models, analyzed their merits and demerits, and looked into the distance of research direction to driving force in the future.

Memory effect of CO2-hydrate formation in porous media

Fuel ◽  
2021 ◽  
Vol 299 ◽  
pp. 120922
Author(s):  
Zhiang Wen ◽  
Yanbin Yao ◽  
Wanjing Luo ◽  
Xin Lei
Keyword(s):  
Porous Media ◽  
Memory Effect ◽  
Hydrate Formation

scholarly journals Evolutionary economics: Crisis, transformation and metamorphosis

2021 ◽  
pp. 1-8
Author(s):  
Milan Zeleny
Keyword(s):  
Growth Rate ◽  
Productivity Growth ◽  
Driving Force ◽  
Evolutionary Economics ◽  
Regional Economies ◽  
Economic Evolution ◽  
Economic Sectors ◽  
Advanced Economies ◽  
First Time

Most world economies are undergoing fundamental transformations of economic sectors, shifting their employed workforce through the secular sequence of (1. Agriculture⟶2. Industry⟶3. Services⟶4. Government). The productivity growth rate is the driving force. Most advanced economies have reached the final stages of the sequence. Assorted recessions, crises and stagnations are simply cofluent, accompanying phenomena. Crises might be cyclical, but economic evolution is unidirectional. Traditional economics can hardly distinguish phenomena of crisis from those of the transformation. Because there is no “fifth sector”, some economies are entering the phase of metamorphosis, for the first time in history. Metamorphosis is manifested through deglobalization, relocalization and autonomization of local and regional economies. We are entering the Age of Entrepreneurship.

Direct insight into the formation driving force, sensitivity and detonation performance of the observed CL-20-based energetic cocrystals

CrystEngComm ◽  
2018 ◽  
Vol 20 (38) ◽  
pp. 5790-5800 ◽  
Author(s):  
Binghui Duan ◽  
Yuanjie Shu ◽  
Ning Liu ◽  
Bozhou Wang ◽  
Xianming Lu ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Driving Force ◽  
Underlying Mechanism ◽  
Detonation Performance ◽  
Force Sensitivity ◽  
Insight Into ◽  
Formation Driving

This work elucidated the underlying mechanism of the dramatic and divergent physicochemical properties of CL-20-based energetic cocrystals.

The effects of SDS, SLES and THF on the growth rate, kinetic behaviors and energy consumption during ethylene hydrate formation process

2019 ◽  
Vol 294 ◽  
pp. 111608 ◽  
Author(s):  
Ali Al-Sowadi ◽  
Hadi Roosta ◽  
Ali Dashti ◽  
S. Arash Pakzad ◽  
Reza Ghasemian ◽  
...  
Keyword(s):  
Growth Rate ◽  
Energy Consumption ◽  
Formation Process ◽  
Hydrate Formation ◽  
Hydrate Formation Process

scholarly journals On the theory of the unsteady-state growth of spherical crystals in metastable liquids

2019 ◽  
Vol 377 (2143) ◽  
pp. 20180209 ◽  
Author(s):  
Dmitri V. Alexandrov ◽  
Irina V. Alexandrova
Keyword(s):  
Growth Rate ◽  
Moving Boundary ◽  
Integral Transform ◽  
Steady State Solution ◽  
Unsteady State ◽  
Power Functions ◽  
Supercooling Degree ◽  
Internal Structures ◽  
State Growth ◽  
Spherical Crystals

Motivated by a large number of applications, we consider the process of non-stationary growth of spherical crystals in a supercooled binary melt. The moving-boundary problem describing the unsteady-state distributions of temperature and impurity concentration around the growing crystal as well as the dynamics of its radius and growth rate is solved by means of the methods of small-parameter expansion and Laplace–Carson integral transform. We show that the growth rate of crystals contains the main contribution (which is proportional to the supercooling degree Δ) and the first correction (which is proportional to Δ 2 t , where t is time). The second correction is also found. The non-stationary temperature and concentration fields are determined as power functions of Δ and t . We demonstrate that the first corrections to the dynamics of crystal radius R ( t ) and its growth rate V ( t ) play an important role. It is shown that R ( t ) and V ( t ) can change more than twice in comparison with the previously known steady-state solution with the course of time. Such a behaviour will significantly modify the dynamics of a polydisperse ensemble of crystals evolving in a metastable liquid. This article is part of the theme issue ‘Heterogeneous materials: metastable and non-ergodic internal structures’.

scholarly journals Effect of Cold Working on the Driving Force of the Crack Growth and Crack Growth Rate of Welded Joints under One Overload

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Hongliang Yang ◽  
He Xue ◽  
Fuqiang Yang ◽  
Shuai Wang
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Creep Rate ◽  
Crack Growth ◽  
Heat Affected Zone ◽  
Driving Force ◽  
Cold Working ◽  
Crack Tip ◽  
Simulation Method ◽  
Fusion Line

To understand the effect of cold working of welding heat-affected zone on the driving force of the crack growth and crack growth rate of stress corrosion cracking (SCC) near the welding fusion line, the finite element simulation method was used to analyze the effect of cold working on the tensile stress of the crack tip at different locations near the fusion line. On this basis, the strain rate of the crack tip in the Ford-Andresen model is replaced by the creep rate of the crack tip, and the creep rate of the crack tip is used as driving force for the crack growth of SCC. The effect of the cold working level at the heat-affected zone on the driving force of the crack growth and crack growth rate of SCC are analyzed, and driving force of the crack growth and crack growth rate of SCC after one overload was compared.

scholarly journals Modeling of Sedimentation and Creaming in Suspensions and Pickering Emulsions

Fluids ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 186 ◽  
Author(s):  
Rajinder Pal
Keyword(s):  
Modeling And Simulation ◽  
Strong Influence ◽  
Water Interface ◽  
Pickering Emulsions ◽  
Hindered Settling ◽  
Drift Flux ◽  
Three Phase ◽  
Oil Water ◽  
Single Droplets ◽  
Emulsions And Suspensions

Suspensions and emulsions are prone to kinetic instabilities of sedimentation and creaming, wherein the suspended particles and droplets fall or rise through a matrix fluid. It is important to understand and quantify sedimentation and creaming in such dispersed systems as they affect the shelf-life of products manufactured in the form of suspensions and emulsions. In this article, the unhindered and hindered settling/creaming behaviors of conventional emulsions and suspensions are first reviewed briefly. The available experimental data on settling/creaming of concentrated emulsions and suspensions are interpreted in terms of the drift flux theory. Modeling and simulation of nanoparticle-stabilized Pickering emulsions are carried out next. The presence of nanoparticles at the oil/water interface has a strong influence on the creaming/sedimentation behaviors of single droplets and swarm of droplets. Simulation results clearly demonstrate the strong influence of three-phase contact angle of nanoparticles present at the oil/water interface. This is the first definitive study dealing with modeling and simulation of unhindered and hindered creaming and sedimentation behaviors of nanoparticle-stabilized Pickering emulsions.

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