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Ryo Ohmura - One of the best experts on this subject based on the ideXlab platform.
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Phase Equilibrium temperature and dissociation heat of ionic semiclathrate hydrate formed with tetrabutylammonium butyrate
Fluid Phase Equilibria, 2017Co-Authors: Yuji Yamauchi, Tatsuro Yamasaki, Fuyuaki Endo, Yuta Arai, Atsushi Hotta, Ryo OhmuraAbstract:Abstract This paper reports the Phase Equilibrium temperature and dissociation heat of ionic semiclathrate hydrate formed with tetrabutylammonium butyrate (TBABu). The temperature – composition Phase diagram of the TBABu hydrate was determined in the mass fraction from 0.10 to 0.44. The highest Equilibrium temperature of TBABu hydrate was 15.4 °C in the mass fraction range from 0.35 to 0.37. On the dissociation heat of DSC measurements, a single heat flow peak of TBABu hydrate excluding ice melting peak was observed at all the mass fraction systems. The largest dissociation heat was 184.9 ± 3.1 kJ/kg at the mass fraction 0.36. TBABu hydrate could potentially be used as a thermal energy storage material.
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Phase Equilibrium of ionic semiclathrate hydrates formed with tetrabutylammonium bromide and tetrabutylammonium chloride
Fluid Phase Equilibria, 2013Co-Authors: Kai Sato, Hiroki Tokutomi, Ryo OhmuraAbstract:This paper reports the accurate Phase Equilibrium measurements of two ionic semiclathrate hydrates with tetrabutylammonium bromide (TBAB) and tetrabutylammonium chloride (TBAC). These ionic semiclathrate hydrates are suggested as cool energy storage media for air-conditioning system since their dissociation heats of Phase transitions are as large as 200–500 kJ/kg and they form at 278–293 K under atmospheric pressure. Tetrabutylammonium bromide and tetrabutylammonium chloride form ionic semiclathrate hydrates and there are several previous reports of the Equilibrium temperatures of these hydrates in the literature. However, there is inconsistency in the literature data of Equilibrium temperatures. Also, there are no clear notifications of experimental procedures and uncertainty of measurements in some of the previous reports. Therefore, we have performed accurate measurements of the Phase Equilibrium of tetrabutylammonium bromide and tetrabutylammonium chloride hydrates and the comparison with the literature data is also made in this paper. The highest Equilibrium temperature for tetrabutylammonium bromide system was 285.9 K at 0.35 < wTBAB < 0.37, where wTBAB denotes the mass fraction of tetrabutylammonium bromide (or the mole fraction of tetrabutylammonium bromide, 0.029 < xTBAB < 0.032), under atmospheric pressure. That for tetrabutylammonium chloride system was 288.2 K at wTBAC = 0.35, where wTBAC is the mass fraction of tetrabutylammonium chloride (or the mole fraction of tetrabutylammonium chloride, xTBAC = 0.034), under atmospheric pressure.
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Phase Equilibrium for structure ii clathrate hydrates formed with fluoromethane propan 2 ol 2 methyl 2 propanol or 2 propanone
The Journal of Chemical Thermodynamics, 2012Co-Authors: Masatoshi Imai, Shinnosuke Nitta, Satoshi Takeya, Ryo OhmuraAbstract:Abstract This paper presents Phase-Equilibrium pressure–temperature data for the clathrate hydrates formed in the three component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are {fluoromethane (CH 3 F) + propan-2-ol + water}, (fluoromethane + 2-methyl-2-propanol + water), and (fluoromethane + 2-propanone + water). The mole ratio of water and the water-soluble material (papan-2-ol, 2-methyl-2-propanol, or 2-propanone) was 17:1. The temperature range over which the Phase-Equilibrium measurements were performed extended to 267.6 K on the lower side and 295.8 K on the higher side. The Phase-Equilibrium pressures in these three systems were found to be lower than that in the binary (fluoromethane + water) system at a given system temperature. The crystallographic structure of the hydrates formed in the systems with 2-methyl-2-propanol and 2-propanone was determined to be structure II based on the powder X-ray diffraction measurements.
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Phase Equilibrium for clathrate hydrates formed with methane ethane propane or carbon dioxide at temperatures below the freezing point of water
Journal of Chemical & Engineering Data, 2008Co-Authors: Keita Yasuda, Ryo OhmuraAbstract:This paper reports the three-Phase (ice + hydrate + guest-rich vapor) Equilibrium pressure−temperature conditions at temperatures (243 to 273) K in the systems of water and each of the following guest gases: methane, ethane, propane, and carbon dioxide. The measurements were also performed for the water-rich liquid + hydrate + guest-rich vapor three-Phase Equilibrium conditions at temperatures above 273 K. The pressure ranges of the present measurements in the four systems are (0.971 to 2.471) MPa in the methane system, (0.122 to 0.637) MPa in the ethane system, (41.0 to 280.0) kPa in the propane system, and (0.364 to 0.963) MPa in the carbon dioxide system. On the basis of the obtained three-Phase Equilibrium data, the quadruple points for the ice + water-rich liquid + hydrate + guest-rich vapor were also determined in the respective systems. The measurements were carried out using the batch, isochoric procedure. Fine-grained ice powders with diameters of (1 to 2) mm were used to form the hydrate. The me...
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Phase Equilibrium for clathrate hydrates formed with difluoromethane or krypton each coexisting with propan 2 ol 2 methyl 2 propanol or 2 propanone
Journal of Chemical & Engineering Data, 2007Co-Authors: Shuntaro Imai, Ryo Ohmura, Kumiko Miyake, Yasuhiko H MoriAbstract:This paper presents Phase-Equilibrium pressure−temperature data for the clathrate hydrates formed in six three-component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are difluoromethane + propan-2-ol + water, difluoromethane + 2-methyl-2-propanol + water, difluoromethane + 2-propanone + water, krypton + propan-2-ol + water, krypton + 2-methyl-2-propanol + water, and krypton + 2-propanone + water. The temperature range over which the Phase-Equilibrium measurements were performed using each system extended to (268.65 to 266.75) K on the lower side and (284.05 to 293.35) K on the higher side. The Phase-Equilibrium temperatures in the three difluoromethane-containing systems were found to be lower than that in the binary difluoromethane + water system at the same system pressure above 0.2 MPa at which the Equilibrium temperature in the binary system is nearly 275 K. On the contrary, the Phase-Equilibrium temperatures in the thre...
Yasuhiko H Mori - One of the best experts on this subject based on the ideXlab platform.
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Phase Equilibrium for clathrate hydrates formed with difluoromethane or krypton each coexisting with propan 2 ol 2 methyl 2 propanol or 2 propanone
Journal of Chemical & Engineering Data, 2007Co-Authors: Shuntaro Imai, Ryo Ohmura, Kumiko Miyake, Yasuhiko H MoriAbstract:This paper presents Phase-Equilibrium pressure−temperature data for the clathrate hydrates formed in six three-component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are difluoromethane + propan-2-ol + water, difluoromethane + 2-methyl-2-propanol + water, difluoromethane + 2-propanone + water, krypton + propan-2-ol + water, krypton + 2-methyl-2-propanol + water, and krypton + 2-propanone + water. The temperature range over which the Phase-Equilibrium measurements were performed using each system extended to (268.65 to 266.75) K on the lower side and (284.05 to 293.35) K on the higher side. The Phase-Equilibrium temperatures in the three difluoromethane-containing systems were found to be lower than that in the binary difluoromethane + water system at the same system pressure above 0.2 MPa at which the Equilibrium temperature in the binary system is nearly 275 K. On the contrary, the Phase-Equilibrium temperatures in the thre...
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Phase Equilibrium for clathrate hydrates formed with difluoromethane either cyclopentane or tetra n butylammonium bromide
Journal of Chemical & Engineering Data, 2005Co-Authors: Shuntaro Imai, Ryo Ohmura, Kazunori Okutani, Yasuhiko H MoriAbstract:This paper presents Phase Equilibrium data for the clathrate hydrates formed in two three-component systemsa difluoromethane + cyclopentane + water system and a difluoromethane + tetra-n-butylammonium bromide + water system. The vapor + liquid + liquid + hydrate four-Phase Equilibrium in the former system was measured at pressures from 0.027 MPa to 1.544 MPa and at temperatures from 280.45 K to 299.75 K, while the vapor + liquid + hydrate three-Phase Equilibrium in the latter system was measured at pressures from 0.175 MPa to 1.215 MPa and temperatures from 286.45 K to 289.95 K. The pressure in the former four-Phase Equilibrium was found to be lower than that in the two-component difluoromethane + water system by an extent from 0.3 MPa to 0.9 MPa over the temperature range from 280.45 K to 294.1 K, the upper quadruple point for the two-component system. The three-Phase Equilibrium pressure of the difluoromethane + tetra-n-butylammonium bromide + water system has a strong temperature dependency such that, ...
G P Rangaiah - One of the best experts on this subject based on the ideXlab platform.
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evaluation of covariance matrix adaptation evolution strategy shuffled complex evolution and firefly algorithms for Phase stability Phase Equilibrium and chemical Equilibrium problems
Chemical Engineering Research & Design, 2012Co-Authors: Seifeddeen K Fateen, Adrian Bonillapetriciolet, G P RangaiahAbstract:a b s t r a c t Phase Equilibrium calculations and Phase stability analysis of reactive and non-reactive systems play a significant role in the simulation, design and optimization of reaction and separation processes in chemical engineering. These challenging problems, which are often multivariable and non-convex, require global optimization methods for solving them. Stochastic global optimization algorithms have shown promise in providing reliable and efficient solutions for these thermodynamic problems. In this study, we evaluate three alternative global optimization algorithms for Phase and chemical Equilibrium calculations, namely, Covariant Matrix Adaptation-Evolution Strategy (CMA-ES), Shuffled Complex Evolution (SCE) and Firefly Algorithm (FA). The performance of these three stochastic algorithms was tested and compared to identify their relative strengths for Phase Equilibrium and Phase stability problems. The Phase Equilibrium problems include both multi-component systems with and without chemical reactions. FA was found to be the most reliable among the three techniques, whereas CMA-ES can find the global minimum reliably and accurately even with a smaller number of iterations.
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a review on global optimization methods for Phase Equilibrium modeling and calculations
The Open Thermodynamics Journal, 2011Co-Authors: Haibo Zhang, Adrian Bonillapetriciolet, G P RangaiahAbstract:The Phase Equilibrium modeling for multi-component systems is essential in process systems engineering. In particular, Phase stability analysis, Gibbs free energy minimization and estimation of parameters in thermodynamic models are challenging global optimization problems involved in Phase Equilibrium calculations and modeling for both reactive and non-reactive systems. To date, many significant works have been performed in the area of global optimization, and several algorithms and computational contributions of global optimization have been used for solving these problems; global optimization methods used include both deterministic and stochastic algorithms. To the best of our knowledge, there is no review in the literature that focuses on the global optimization methods and their applications to Phase Equilibrium modeling and calculations. In this paper, we briefly describe selected deterministic and stochastic optimization algorithms, and then review their use for Phase stability analysis, Gibbs free energy minimization and parameter estimation in Phase Equilibrium models. In short, we provide a general overview of global optimization for modeling and calculating the Phase behavior of systems with and without chemical reactions including the prediction of azeotropes and critical points.
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tabu search for global optimization of continuous functions with application to Phase Equilibrium calculations
Computers & Chemical Engineering, 2003Co-Authors: G P RangaiahAbstract:Abstract Tabu (or taboo) search (TS) has been successfully applied to combinatorial optimization but it has not been used for global optimization of many continuous functions including Phase Equilibrium calculations via Gibbs free energy minimization. In this study, a version of TS, namely, enhanced continuous TS (ECTS), is first tried for benchmark test functions having multiple minima and then evaluated for Phase Equilibrium calculations. Examples for the latter involve several components, typical conditions and common thermodynamic models. Performance of ECTS is compared with a genetic algorithm (GA). The results show that both TS and GA have high reliability in locating the global minimum, and that TS converges faster than GA thus reducing the computational time and number of function evaluations.
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a study of equation solving and gibbs free energy minimization methods for Phase Equilibrium calculations
Chemical Engineering Research & Design, 2002Co-Authors: Y S Teh, G P RangaiahAbstract:Phase Equilibrium calculations are often involved in the design, simulation, and optimization of chemical processes. Reported methods for these calculations are based on either equation-solving or Gibbs free energy minimization approaches. The main objective of this work is to compare selected methods for these two approaches, in terms of reliability to find the correct solution, computational time, and number of K-value evaluations. For this, four equation-solving and three free minimization methods have been selected and applied to commonly encountered vapour–liquid Equilibrium (VLE), liquid–liquid Equilibrium (LLE), and vapour–liquid–liquid Equilibrium (VLLE) examples involving multiple components and popular thermodynamic models. Detailed results show that the equation-solving method based on the Rachford–Rice formulation accompanied by mean value theorem and Wegstein's projection is reliable and efficient for two-Phase Equilibrium calculations not having local minima. When there are multiple minima and for three-Phase Equilibrium, the stochastic method, genetic algorithm (GA) followed by modified simplex method of Nelder and Mead (NM) is more reliable and desirable. Generic programs for numerical methods are ineffective for Phase Equilibrium calculations. These findings are of interest and value to researchers and engineers working on Phase Equilibrium calculations and/or developing thermodynamic models for Phase behaviour.
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evaluation of genetic algorithms and simulated annealing for Phase Equilibrium and stability problems
Fluid Phase Equilibria, 2001Co-Authors: G P RangaiahAbstract:Phase Equilibrium calculations require global minimization of free energy, and Phase stability analysis too often involves global minimization of tangent plane distance function (TPDF). In this study, two stochastic global optimization techniques, namely, genetic algorithm (GA) and simulated annealing (SA) are evaluated and compared for Phase Equilibrium and stability problems. Typical examples and different thermodynamic models are considered. The results show that GA is generally more efficient and reliable than SA for Phase Equilibrium calculations. Both GA and SA exhibited poor reliability for locating the global minimum of free energy function for some complex Phase Equilibrium systems. For these problems, a hybrid GA incorporating SA for individual learning, is proposed and its improved capability is shown. The results on Phase stability problems show that GA is able to locate the global minimum of TPDF with 100% reliability in all the examples tried. It is also found to be very efficient compared to other global techniques reported in the literature.
Shuntaro Imai - One of the best experts on this subject based on the ideXlab platform.
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Phase Equilibrium for clathrate hydrates formed with difluoromethane or krypton each coexisting with propan 2 ol 2 methyl 2 propanol or 2 propanone
Journal of Chemical & Engineering Data, 2007Co-Authors: Shuntaro Imai, Ryo Ohmura, Kumiko Miyake, Yasuhiko H MoriAbstract:This paper presents Phase-Equilibrium pressure−temperature data for the clathrate hydrates formed in six three-component systems each consisting of a hydrate-forming gas, a water-soluble freezing-point depression material, and water. These systems are difluoromethane + propan-2-ol + water, difluoromethane + 2-methyl-2-propanol + water, difluoromethane + 2-propanone + water, krypton + propan-2-ol + water, krypton + 2-methyl-2-propanol + water, and krypton + 2-propanone + water. The temperature range over which the Phase-Equilibrium measurements were performed using each system extended to (268.65 to 266.75) K on the lower side and (284.05 to 293.35) K on the higher side. The Phase-Equilibrium temperatures in the three difluoromethane-containing systems were found to be lower than that in the binary difluoromethane + water system at the same system pressure above 0.2 MPa at which the Equilibrium temperature in the binary system is nearly 275 K. On the contrary, the Phase-Equilibrium temperatures in the thre...
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Phase Equilibrium for clathrate hydrates formed with difluoromethane either cyclopentane or tetra n butylammonium bromide
Journal of Chemical & Engineering Data, 2005Co-Authors: Shuntaro Imai, Ryo Ohmura, Kazunori Okutani, Yasuhiko H MoriAbstract:This paper presents Phase Equilibrium data for the clathrate hydrates formed in two three-component systemsa difluoromethane + cyclopentane + water system and a difluoromethane + tetra-n-butylammonium bromide + water system. The vapor + liquid + liquid + hydrate four-Phase Equilibrium in the former system was measured at pressures from 0.027 MPa to 1.544 MPa and at temperatures from 280.45 K to 299.75 K, while the vapor + liquid + hydrate three-Phase Equilibrium in the latter system was measured at pressures from 0.175 MPa to 1.215 MPa and temperatures from 286.45 K to 289.95 K. The pressure in the former four-Phase Equilibrium was found to be lower than that in the two-component difluoromethane + water system by an extent from 0.3 MPa to 0.9 MPa over the temperature range from 280.45 K to 294.1 K, the upper quadruple point for the two-component system. The three-Phase Equilibrium pressure of the difluoromethane + tetra-n-butylammonium bromide + water system has a strong temperature dependency such that, ...
Hongkun Zhao - One of the best experts on this subject based on the ideXlab platform.
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saturated vapor pressure of 4 fluorophthalic anhydride and 4 chlorophthalic anhydride and isobaric vapor liquid Phase Equilibrium of 4 fluorophthalic anhydride 4 chlorophthalic anhydride measurement and modeling
Fluid Phase Equilibria, 2015Co-Authors: Shuo Han, Jing Wang, Ganbing Yao, Hongkun ZhaoAbstract:Abstract The saturated vapor pressures of 4-fluorophthalic anhydride and 4-chlorophthalic anhydride at various temperatures ranging from T = (426 to 560) K, and the isobaric vapor–liquid Phase Equilibrium data for binary system of 4-fluorophthalic anhydride (1) + 4-chlorophthalic anhydride (2) at pressures of 21.33 kPa, 41.33 kPa, 61.33 kPa and 81.33 kPa were measured experimentally by means of an inclined ebulliometer. The relationship between saturated vapor pressure and temperature was fitted by using two Antoine equations and the Antoine constants were acquired for 4-fluorophthalic anhydride and 4-chlorophthalic anhydride, respectively. The semi-empirical method, Herington method was employed to test thermodynamic consistency of the vapor–liquid Equilibrium data. The isobaric vapor–liquid Phase Equilibrium data were fitted with three thermodynamic models, which corresponded to Wilson, NRTL and UNIQUAC. The parameters of the three activity coefficient models were obtained by the method of nonlinear least-square regression. The calculated vapor–liquid Phase Equilibrium data with the three activity coefficient models agree very well with the experimental values.
