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Yi Wang - One of the best experts on this subject based on the ideXlab platform.
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Optimization of the Production Pressure for Hydrate Dissociation by Depressurization
'American Chemical Society (ACS)', 2020Co-Authors: Li Xiao-yan, Yi Wang, Li Xiao-sen, Yu ZhangAbstract:Natural gas hydrate is considered as a promising energy resource in the future. How to choose a suitable production pressure is a key issue when depressurization is taken as the production way of gas hydrate. In this study, we conducted the experiments of methane hydrate dissociation under different production pressures. The influences of production pressure on the hydrate dissociation rate and the method to optimize the production pressure were studied. The experimental results illustrated that two stages were contained in the hydrate dissociation by depressurization: the depressurization stage (DS) and the constant pressure stage (CPS). In the DS, the sensible heat of the sediments was used for hydrate dissociation, and the hydrate dissociation amount increased with the decrease of the production pressure. In the CPS, the required heat for hydrate dissociation was transferred from the surroundings. As the production pressure decreased, the hydrate dissociation rate increased. Although the lower production pressure can improve the hydrate dissociation rate, the energy input of hydrate production in field for depressurization with the lower production pressure could be larger than that with the higher production pressure. In order to improve the production efficiency, an optimizing method of production pressure was first proposed. Based on the experimental data, the optimum production pressure was calculated with this method. The calculation result indicates that the production pressure should be as close to the pressure of hydrate Quadruple Point (2.56 MPa) as possible. Moreover, it is worth noting that the optimum production pressure in field production could be different from that obtained by experiments because the optimum production pressure is determined by the actual function of the energy input in field. However, the evaluation method is universal
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pilot scale experimental test on gas production from methane hydrate decomposition using depressurization assisted with heat stimulation below Quadruple Point
International Journal of Heat and Mass Transfer, 2019Co-Authors: Yi Wang, Jingchun FengAbstract:Abstract Natural gas hydrate can be regarded as alternative energy source in future. Therefore, developing approaches for enhancing gas recovery from hydrate reservoir is attracting extensive attention. A Pilot-Scale Hydrate Simulator (PHS) with the effective volume of 117.8 L was applied for investigating gas recovery from hydrate dissociation below Quadruple Point in porous media, where hydrate exists with ice, water, and methane gas. Depressurization and depressurization assisted with heat stimulation below Quadruple Point were selected as the hydrate decomposition method. The influence of heat stimulation on hydrate decomposition below Quadruple Point was evaluated. The experimental results indicate that the hydrate decomposition rate can be greatly enhanced by decreasing the pressure below Quadruple Point, because ice can be generated during hydrate decomposition below Quadruple Point. Heat released by ice formation can immediately supply to hydrate decomposition. During hydrate decomposition experiment by depressurization assisted with heat stimulation, the influence of heat stimulation on hydrate recovery below Quadruple Point is not obviously, because injected heat is used for ice melting rather than hydrate dissociation. Therefore, heat stimulation may not enhance hydrate dissociation below Quadruple Point.
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Pilot-scale experimental test on gas production from methane hydrate decomposition using depressurization assisted with heat stimulation below Quadruple Point
'Elsevier BV', 2019Co-Authors: Yi Wang, Feng Jing-chun, Li Xiao-senAbstract:Natural gas hydrate can be regarded as alternative energy source in future. Therefore, developing approaches for enhancing gas recovery from hydrate reservoir is attracting extensive attention. A Pilot-Scale Hydrate Simulator (PHS) with the effective volume of 117.8 L was applied for investigating gas recovery from hydrate dissociation below Quadruple Point in porous media, where hydrate exists with ice, water, and methane gas. Depressurization and depressurization assisted with heat stimulation below Quadruple Point were selected as the hydrate decomposition method. The influence of heat stimulation on hydrate decomposition below Quadruple Point was evaluated. The experimental results indicate that the hydrate decomposition rate can be greatly enhanced by decreasing the pressure below Quadruple Point, because ice can be generated during hydrate decomposition below Quadruple Point. Heat released by ice formation can immediately supply to hydrate decomposition. During hydrate decomposition experiment by depressurization assisted with heat stimulation, the influence of heat stimulation on hydrate recovery below Quadruple Point is not obviously, because injected heat is used for ice melting rather than hydrate dissociation. Therefore, heat stimulation may not enhance hydrate dissociation below Quadruple Point. (C) 2018 Elsevier Ltd. All rights reserved
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Large Scale Experimental Evaluation to Methane Hydrate Dissociation below Quadruple Point by Depressurization Assisted with Heat Stimulation
Energy Procedia, 2017Co-Authors: Jingchun Feng, Yi WangAbstract:Abstract The Pilot-Scale Hydrate Simulator (PHS), a three-dimensional 117.8 L pressure vessel, is applied to study the methane hydrate dissociation below the Quadruple Point in the sandy sediment in this work. The hydrate dissociation behaviors below and above the Quadruple Point by depressurization method and depressurization assisted with heat stimulation method are compared. The results indicate that methane hydrate dissociation below the Quadruple Point causes ice formation, which can strongly enhance the dissociation rate of the hydrate. The water generated from hydrate dissociation below the Quadruple Point may immediately form ice. Meanwhile, the hydrate dissociation below the Quadruple Point consumes the latent heat released by ice formation. In addition, it is found by depressurization assisted with heat stimulation that the heat injection has little influence on hydrate dissociation, because the injected heat is used for ice melting rather than hydrate dissociation.
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large scale experimental evaluation to methane hydrate dissociation below Quadruple Point in sandy sediment
Applied Energy, 2016Co-Authors: Yi Wang, Yu Zhang, Jingchun Feng, Xiaosen Li, Gang LiAbstract:The Pilot-Scale Hydrate Simulator (PHS), a three-dimensional 117.8L pressure vessel, is applied to study the methane hydrate dissociation below the Quadruple Point in the sandy sediment in this work. The hydrate dissociation behaviors below and above the Quadruple Point are compared. The influences of the production pressure, the initial reservoir temperature, and the water saturation on the hydrate dissociation below the Quadruple Point by depressurization are investigated. The results indicate that methane hydrate dissociation below the Quadruple Point causes ice formation, which can strongly enhance the dissociation rate of the hydrate. The water generated from hydrate dissociation below the Quadruple Point may immediately form ice and the pore water in the reservoir turns into ice at the same time. Meanwhile, the hydrate dissociation below the Quadruple Point consumes the latent heat released by ice formation. The lower production pressure causes the higher driving force for hydrate dissociation and ice formation, which results in the higher dissociation rate of the hydrate. In addition, when the production pressure is lower than the Quadruple Point, a lower initial reservoir temperature is favorable for ice formation, which leads to the higher hydrate dissociation rate. The experimental results from hydrate dissociation in the ‘water-saturated’ reservoir and ‘gas-saturated’ reservoir indicate that the rate of ice formation is slower in the ‘water-saturated’ reservoir.
Jingchun Feng - One of the best experts on this subject based on the ideXlab platform.
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pilot scale experimental test on gas production from methane hydrate decomposition using depressurization assisted with heat stimulation below Quadruple Point
International Journal of Heat and Mass Transfer, 2019Co-Authors: Yi Wang, Jingchun FengAbstract:Abstract Natural gas hydrate can be regarded as alternative energy source in future. Therefore, developing approaches for enhancing gas recovery from hydrate reservoir is attracting extensive attention. A Pilot-Scale Hydrate Simulator (PHS) with the effective volume of 117.8 L was applied for investigating gas recovery from hydrate dissociation below Quadruple Point in porous media, where hydrate exists with ice, water, and methane gas. Depressurization and depressurization assisted with heat stimulation below Quadruple Point were selected as the hydrate decomposition method. The influence of heat stimulation on hydrate decomposition below Quadruple Point was evaluated. The experimental results indicate that the hydrate decomposition rate can be greatly enhanced by decreasing the pressure below Quadruple Point, because ice can be generated during hydrate decomposition below Quadruple Point. Heat released by ice formation can immediately supply to hydrate decomposition. During hydrate decomposition experiment by depressurization assisted with heat stimulation, the influence of heat stimulation on hydrate recovery below Quadruple Point is not obviously, because injected heat is used for ice melting rather than hydrate dissociation. Therefore, heat stimulation may not enhance hydrate dissociation below Quadruple Point.
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Large Scale Experimental Evaluation to Methane Hydrate Dissociation below Quadruple Point by Depressurization Assisted with Heat Stimulation
Energy Procedia, 2017Co-Authors: Jingchun Feng, Yi WangAbstract:Abstract The Pilot-Scale Hydrate Simulator (PHS), a three-dimensional 117.8 L pressure vessel, is applied to study the methane hydrate dissociation below the Quadruple Point in the sandy sediment in this work. The hydrate dissociation behaviors below and above the Quadruple Point by depressurization method and depressurization assisted with heat stimulation method are compared. The results indicate that methane hydrate dissociation below the Quadruple Point causes ice formation, which can strongly enhance the dissociation rate of the hydrate. The water generated from hydrate dissociation below the Quadruple Point may immediately form ice. Meanwhile, the hydrate dissociation below the Quadruple Point consumes the latent heat released by ice formation. In addition, it is found by depressurization assisted with heat stimulation that the heat injection has little influence on hydrate dissociation, because the injected heat is used for ice melting rather than hydrate dissociation.
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large scale experimental evaluation to methane hydrate dissociation below Quadruple Point in sandy sediment
Applied Energy, 2016Co-Authors: Yi Wang, Yu Zhang, Jingchun Feng, Xiaosen Li, Gang LiAbstract:The Pilot-Scale Hydrate Simulator (PHS), a three-dimensional 117.8L pressure vessel, is applied to study the methane hydrate dissociation below the Quadruple Point in the sandy sediment in this work. The hydrate dissociation behaviors below and above the Quadruple Point are compared. The influences of the production pressure, the initial reservoir temperature, and the water saturation on the hydrate dissociation below the Quadruple Point by depressurization are investigated. The results indicate that methane hydrate dissociation below the Quadruple Point causes ice formation, which can strongly enhance the dissociation rate of the hydrate. The water generated from hydrate dissociation below the Quadruple Point may immediately form ice and the pore water in the reservoir turns into ice at the same time. Meanwhile, the hydrate dissociation below the Quadruple Point consumes the latent heat released by ice formation. The lower production pressure causes the higher driving force for hydrate dissociation and ice formation, which results in the higher dissociation rate of the hydrate. In addition, when the production pressure is lower than the Quadruple Point, a lower initial reservoir temperature is favorable for ice formation, which leads to the higher hydrate dissociation rate. The experimental results from hydrate dissociation in the ‘water-saturated’ reservoir and ‘gas-saturated’ reservoir indicate that the rate of ice formation is slower in the ‘water-saturated’ reservoir.
Xiaobing Ren - One of the best experts on this subject based on the ideXlab platform.
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large electrostrain with nearly vanished hysteresis in eco friendly perovskites by building coexistent glasses near Quadruple Point
Nano Energy, 2021Co-Authors: Dong Wang, Xiaobing Ren, Le Zhang, Lixue Zhang, Danyang Wang, Xiaoqing PanAbstract:Abstract One of the key questions in the development of eco-friendly piezoelectrics lies in how to achieve large hysteresis-free electrostrain responses in a facile and effective manner, to meet the requirements of high-precision electromechanical devices. Here, through integrating phase-field modeling and experimental approach, a highly effective strategy is proposed for large electrostrain outputs with negligible hysteresis in lead-free perovskite oxide ferroelectrics, by building coexistent glasses with diverse local symmetries near a Quadruple Point rendering low energy barriers between different polar states. Guided by phase-field simulations, a superior electrostrain of ~ 0.21% with nearly-zero hysteresis is obtained at the constructed glasses region near the Quadruple Point of Bi-doped Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 ceramics, outperforming almost state-of-the-art lead-free piezoelectric substitutions when taking both electrostrain and hysteresis into account. The strategy of building coexistent glasses near the Quadruple Point provides a novel design paradigm for high-performance piezoelectric materials in the application of high-precision actuators.
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existence of a Quadruple Point in a binary ferroelectric phase diagram
Physical Review B, 2021Co-Authors: Sen Yang, Yu Wang, Dong Wang, Luo Zhao, Jinghui Gao, Yunzhi Wang, Xiaobing RenAbstract:In experimentally measured temperature-composition ferroelectric phase diagrams of ${\mathrm{BaTiO}}_{3}$-based binary systems, a Quadruple Point where cubic (C), tetragonal (T), orthorhombic (O), and rhombohedral (R) phases converge has been frequently reported in previous work. More interestingly, the Quadruple Points are experimentally found to behave as a critical Point with large enhancement in properties. However, it has remained a fundamental question as to whether a Quadruple Point in a binary ferroelectric system defies the thermodynamic phase rule and whether such a Point necessarily goes critical. In this study, it is demonstrated by Landau theory that a C-T-O-R Quadruple Point in a binary ferroelectric system can only exist in the form of a unique type of critical Point at which two first-order transition lines and two second-order ones meet, and such critical Quadruple Points do not defy the thermodynamic phase rule. It is further shown that at such a critical C-T-O-R Quadruple Point, the system exhibits infinitely large piezoelectric coefficients, which agrees with the high piezoelectricity observed at the C-T-O-R Quadruple Point in a number of ${\mathrm{BaTiO}}_{3}$-based binary ferroelectric systems and also helps to explain the large piezoelectricity obtained at the morphotropic phase boundaries of these Quadruple Point based systems.
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large piezoelectricity and dielectric permittivity in batio3 xbasno3 system the role of phase coexisting
EPL, 2012Co-Authors: Yonggang Yao, Dong Wang, Chao Zhou, Yaodong Yang, Xiaobing RenAbstract:We report ultrahigh dielectric and piezoelectric properties in BaTiO3-xBaSnO3 ceramics at its quasi-Quadruple Point, a Point where four phases (Cubic-Tetragonal-Orthorhombic- Rhombohedral) nearly coexist together in the temperature-composition phase diagram. At this Point, dielectric permittivity reaches ∼ 75000, a 6-7-fold increase compared with that of pure BaTiO3 at its Curie Point; the piezoelectric coefficient d33 reaches 697 pC/N, 5 times higher than that of pure BaTiO3. Also, a quasi-Quadruple Point system exhibits double morphotropic phase boundaries, which can be used to reduce the temperature and composition sensitivity of its high piezoelectric properties. A Landau-Devonshire model shows that four-phase coexisting leading to minimizing energy barriers for both polarization rotation and extension might be the origin of giant dielectric and piezoelectric properties around this Point. Copyright c � EPLA, 2012
Kavssery Parameswaran Ananthapadmanabhan - One of the best experts on this subject based on the ideXlab platform.
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solubility limits and phase diagrams for fatty acids in anionic sles and zwitterionic capb micellar surfactant solutions
Journal of Colloid and Interface Science, 2012Co-Authors: Sylvia S Tzocheva, Peter A Kralchevsky, Krassimir D Danov, Gergana Georgieva, Albert Joseph Post, Kavssery Parameswaran AnanthapadmanabhanAbstract:Abstract By analysis of experimental data, a quantitative theoretical interpretation of the solubility limit of medium- and long-chain fatty alcohols in micellar solutions of water-soluble surfactants is presented. A general picture of the phase behavior of the investigated systems is given in the form of phase diagrams. The limited solubility of the fatty alcohols in the micelles of conventional surfactants is explained with the precipitation of their monomers in the bulk, rather than with micelle phase separation. The long chain fatty alcohols (with n = 14, 16 and 18 carbon atoms) exhibit an ideal mixing in the micelles of the anionic surfactant sodium laurylethersulfate (SLES) and the zwitterionic surfactant cocamidopropyl betaine (CAPB) at temperatures of 25, 30, 35 and 40 °C. Deviations from ideality are observed for the alcohols of shorter chain (n = 10 and 12), which can be explained by a mismatch with the longer chains of the surfactant molecules. Using the determined thermodynamic parameters of the systems, their phase diagrams are constructed. Such a diagram consists of four domains, viz. mixed micelles; coexistent micelles and precipitate (dispersed crystallites or droplets); precipitate without micelles, and molecular solution. The four boundary lines intersect in a Quadruple Point, Q. For ionic surfactants (like SLES), a detailed theory for calculating the boundary lines of the phase diagrams is developed and verified against data for the positions of the kinks in surface tension isotherms. The theory takes into account the electrostatic interactions in the micellar solutions and the effect of counterion binding. The results can be useful for a quantitative interpretation and prediction of the phase behavior of mixed solutions of two (or more) surfactants, one of them being water soluble and forming micelles, whereas the other one has a limited water solubility, but readily forms mixed micelles with the former surfactant.
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solubility limits and phase diagrams for fatty acids in anionic sles and zwitterionic capb micellar surfactant solutions
Joint International Conference on Information Sciences, 2012Co-Authors: Sylvia S Tzocheva, Peter A Kralchevsky, Krassimir D Danov, Albert Joseph Post, Gergana S Georgieva, Kavssery Parameswaran AnanthapadmanabhanAbstract:The limiting solubility of fatty acids in micellar solutions of the anionic surfactant sodium laurylethersulfate (SLES) and the zwitterionic surfactant cocamidopropyl betaine (CAPB) is experimentally determined. Saturated straight-chain fatty acids with n=10, 12, 14, 16, and 18 carbon atoms were investigated at working temperatures of 25, 30, 35, and 40°C. The rise of the fatty acid molar fraction in the micelles is accompanied by an increase in the equilibrium concentration of acid monomers in the aqueous phase. Theoretically, the solubility limit is explained with the precipitation of fatty acid crystallites when the monomer concentration reaches the solubility limit of the acid in pure water. In agreement with theory, the experiment shows that the solubility limit is proportional to the surfactant concentration. For ideal mixtures, the plot of the log of solubility limit vs. the chainlength, n, must be a straight line, which is fulfilled for n=14, 16, and 18. For the fatty acids of shorter chains, n=10 and 12, a deviation from linearity is observed, which is interpreted as non-ideal mixing due to a mismatch between the chainlengths of the surfactant and acid. The data analysis yields the solubilization energy and the interaction parameter for the fatty acid molecules in surfactant micelles. By using the determined parameter values, phase diagrams of the investigated mixed solutions are constructed. The four inter-domain boundary lines intersect in a Quadruple Point, whose coordinates have been determined. The results can be applied for the interpretation and prediction of the solubility, and phase behavior of medium- and long-chain fatty acids and other amphiphiles that are solubilizable in micellar surfactant solutions, as well as for determining the critical micellization concentration (CMC) of the respective mixed solution.
Jiro Nagao - One of the best experts on this subject based on the ideXlab platform.
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experimental evaluation of the gas recovery factor of methane hydrate in sandy sediment
RSC Advances, 2014Co-Authors: Yoshihiro Konno, Kazunori Shinjou, Jiro NagaoAbstract:Gas production tests have been conducted on artificial sandy sediments saturated by methane hydrate and water using a unique apparatus referred to as High-pressure Giant Unit for Methane-hydrate Analyses (HiGUMA), which is the world's largest reservoir simulating vessel intended for gas hydrate analysis. The gas recovery factor was investigated at various depressurization schemes, including one-step depressurization, multistep depressurization, and depressurization below the Quadruple Point of methane hydrate. The gas production rate increased during the depressurization process with sediment temperature reduction; however, the rate decrease and stabilized at a very low level after the temperature reached a newly established equilibrium condition. This result indicates that an appropriate heat of the hydrate-bearing sediments is a crucial factor for driving hydrate dissociation. The potential economic recovery factor was 14% for 4.6 MPa of production pressure in the one-step depressurization. In the multistep depressurization, the recovery factor was increased with a reduction in production pressure and showed values of 13%, 31%, and 40% for 4.0 MPa, 3.1 MPa, and 2.5 MPa, respectively. However, depressurization above the Quadruple Point could not dissociate all the existing hydrate due to the lack of heat. In contrast, it was determined that 65% of the in-place methane could be produced when the production pressure was decreased to 2.1 MPa, which is below the Quadruple Point, because the latent heat of ice formation was efficiently used for hydrate dissociation. The results show that intentional ice formation by adjusting production pressure can potentially enhance methane hydrate recovery at a comparable level of conventional natural gas production.
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dissociation behavior of methane hydrate in sandy porous media below the Quadruple Point
Energy & Fuels, 2012Co-Authors: Yoshihiro Konno, Jiro Nagao, Takashi Uchiumi, Hiroyuki Oyama, Yusuke Jin, Yoshihiro Masuda, Hisanao OuchiAbstract:To investigate the effect of ice formation on gas production from gas-hydrate-bearing sandy porous media, we conducted dissociation experiments using artificial methane hydrate cores by depressurizing them to below the Quadruple Point. We prepared water- and gas-saturated hydrate cores to evaluate the influence of water content on ice formation. The experiments showed that gas production under the ice formation regime had a unique high-rate period in the early stage of production, whereas under the water generation regime, the high-rate period was not observed. During ice formation, the gas production rates of the water-saturated cores exhibited greater acceleration than those of the gas-saturated cores. We conducted numerical simulations using the hydrate reservoir simulator MH21-HYDRES for quantitative analyses. The results showed that ice forms faster in a water-saturated core because of the availability of pore water for ice formation. This further enhances the gas production rate of a water-saturated core. Sensitivity analyses indicated that the rate of ice formation and the permeability reduction by ice formation are key model parameters affecting gas production behavior. From the experimental and numerical investigations, we conclude that depressurization-induced gas production can be accelerated by ice formation during hydrate dissociation at a pressure below the Quadruple Point.