Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over...Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over the entire composition range at temperatures 298.15, 303.15 and 308.15 K. From these experimental data, the excess available volume, E a V , excess free volume, E f V , excess isothermal compressibility, E T β , excess thermal expansion coefficient, E α , and excess internal pressure, E i π , are calculated. The variation of these properties with composition and temperature are discussed in terms of molecular interactions between unlike molecules of the mixtures. It is found that the values of E a V , E f V , E T β and E α are positive and those of E i π are negative for all the mixtures at each temperature studied, indicating the presence of weak interactions between 2M2P and AN/PN/BN molecules. The variations of E a V , E f V , E T β , E α and E i π values with composition indicate that the interactions in these mixtures follow the order: AN<PN<BN, i.e., the 2M2P-nitrile interaction decreases with the increase of alkyl chain length in these nitrile molecules. In addition, the theoretical ultrasonic velocity is calculated using the scaled particle theory and compared with the experimental values.展开更多
The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of sur...The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity.展开更多
More than half a century after its first formulation by Reiss, Frisch and Lebowitz in 1959, scaled particle theory(SPT) has proven its immense usefulness and has become one of the most successful theories in liquid ph...More than half a century after its first formulation by Reiss, Frisch and Lebowitz in 1959, scaled particle theory(SPT) has proven its immense usefulness and has become one of the most successful theories in liquid physics. In recent years, we have strived to extend SPT to fluids confined in a variety of random porous matrices. In this article, we present a timely review of these developments. We have endeavored to present a formulation that is pedagogically more accessible than those presented in various original papers, and we hope this benefits newcomers in their research work. We also use more consistent notations for different cases. In addition, we discuss issues that have been scarcely considered in the literature, e.g., the one-fluid structure of SPT due to the isomorphism between the equation of state for a multicomponent fluid and that for a one-component fluid or the pure-confinement scaling relation that provides a connection between a confined and a bulk fluid.展开更多
We implemented for the first time our radioactive particle tracking as an advanced noninvasive tech- nique to further evaluate and validate our newly developed mechanistic scale-up methodology based on matching the ra...We implemented for the first time our radioactive particle tracking as an advanced noninvasive tech- nique to further evaluate and validate our newly developed mechanistic scale-up methodology based on matching the radial profile of the gas holdup.Two spouted beds with diameters of 0.076 and 0.152 m were used. Three sets of conditions were implemented; i.e., conditions of the reference case, conditions that provided a gas-holdup radial profile similar to that of the reference case, and conditions that provided a gas-holdup radial profile dissimilar to that of the reference case. The results confirm the validation of the scale-up methodology in terms of obtaining closer dimensionless values and radial profiles of compo- nents of the particle velocity, normal stress, shear stress, and turbulent kinetic energy, The results further advance the understanding of gas-solids spouted beds, provide deeper insight into the solids dynamics of the beds and present important benchmarking data for validating computational fluid dynamics codes and models.展开更多
This study presents the interaction between konjac glucanmannan（KGM） and cationic surfactant dodecyl trimethylammonium chloride（DTAC） to provide theoretical guidance and prediction for the experimental design and ...This study presents the interaction between konjac glucanmannan（KGM） and cationic surfactant dodecyl trimethylammonium chloride（DTAC） to provide theoretical guidance and prediction for the experimental design and application of this composite system. Dissipative particle dynamics（DPD） method was used to simulate the interaction between KGM and the cationic surfactant. Influences of concentration, temperature and shear process on the structure and properties of aggregates were mainly examined. The results revealed that the density peak increased with the increase of concentration of KGM. With increasing the temperature, density peak moved to the right and increased, and then decreased when the temperature rose to a certain value. The density peak moved to the right at the low shear rate while decreased at the high one. During simulation, the high viscosity related to the low diffusion rate, which made it difficult to form a large continuous phase.展开更多
Despite advancements in computational resources,the discrete element method(DEM)still requires considerable computational time to solve detailed problems,especially when it comes to the large-scale models.In addition ...Despite advancements in computational resources,the discrete element method(DEM)still requires considerable computational time to solve detailed problems,especially when it comes to the large-scale models.In addition to the geometry scale of the problem,the particle shape has a dramatic effect on the computational cost of DEM.Therefore,many studies have been performed with simplified spherical particles or clumps.Particle scaling is an approach to increase the particle size to reduce the number of particles in the DEM.Although several particle scaling methods have been introduced,there are still some disagreements regarding their applicability to certain aspects of problems.In this study,the effect of particle scalping on the shear behavior of granular material is explored.Real granular particles were scanned and imported as polygonal particles in the direct shear test.The effect of particle size distri-bution,particle angularity,and the amount of scalping were investigated.The results show that particle scalping can simulate the correct shear behavior of the model with significant improvement in computational time.Also,the accuracy of the scalping method depends on the particle angularity and particle size range.展开更多
文摘Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over the entire composition range at temperatures 298.15, 303.15 and 308.15 K. From these experimental data, the excess available volume, E a V , excess free volume, E f V , excess isothermal compressibility, E T β , excess thermal expansion coefficient, E α , and excess internal pressure, E i π , are calculated. The variation of these properties with composition and temperature are discussed in terms of molecular interactions between unlike molecules of the mixtures. It is found that the values of E a V , E f V , E T β and E α are positive and those of E i π are negative for all the mixtures at each temperature studied, indicating the presence of weak interactions between 2M2P and AN/PN/BN molecules. The variations of E a V , E f V , E T β , E α and E i π values with composition indicate that the interactions in these mixtures follow the order: AN<PN<BN, i.e., the 2M2P-nitrile interaction decreases with the increase of alkyl chain length in these nitrile molecules. In addition, the theoretical ultrasonic velocity is calculated using the scaled particle theory and compared with the experimental values.
基金Supported by the National Natural Science Foundation of China （20776040 20876041 20736002） the National Basic Research Program of China （2009CB219902）+1 种基金 the Program for Changjiang Scholars and Innovative Research Team in University of China （Grant IRT0721） the 111 Project （Grant B08021） of China
文摘The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity.
文摘More than half a century after its first formulation by Reiss, Frisch and Lebowitz in 1959, scaled particle theory(SPT) has proven its immense usefulness and has become one of the most successful theories in liquid physics. In recent years, we have strived to extend SPT to fluids confined in a variety of random porous matrices. In this article, we present a timely review of these developments. We have endeavored to present a formulation that is pedagogically more accessible than those presented in various original papers, and we hope this benefits newcomers in their research work. We also use more consistent notations for different cases. In addition, we discuss issues that have been scarcely considered in the literature, e.g., the one-fluid structure of SPT due to the isomorphism between the equation of state for a multicomponent fluid and that for a one-component fluid or the pure-confinement scaling relation that provides a connection between a confined and a bulk fluid.
文摘We implemented for the first time our radioactive particle tracking as an advanced noninvasive tech- nique to further evaluate and validate our newly developed mechanistic scale-up methodology based on matching the radial profile of the gas holdup.Two spouted beds with diameters of 0.076 and 0.152 m were used. Three sets of conditions were implemented; i.e., conditions of the reference case, conditions that provided a gas-holdup radial profile similar to that of the reference case, and conditions that provided a gas-holdup radial profile dissimilar to that of the reference case. The results confirm the validation of the scale-up methodology in terms of obtaining closer dimensionless values and radial profiles of compo- nents of the particle velocity, normal stress, shear stress, and turbulent kinetic energy, The results further advance the understanding of gas-solids spouted beds, provide deeper insight into the solids dynamics of the beds and present important benchmarking data for validating computational fluid dynamics codes and models.
基金supported by the National Natural Science Foundation of China(31471704 and 31271837)
文摘This study presents the interaction between konjac glucanmannan（KGM） and cationic surfactant dodecyl trimethylammonium chloride（DTAC） to provide theoretical guidance and prediction for the experimental design and application of this composite system. Dissipative particle dynamics（DPD） method was used to simulate the interaction between KGM and the cationic surfactant. Influences of concentration, temperature and shear process on the structure and properties of aggregates were mainly examined. The results revealed that the density peak increased with the increase of concentration of KGM. With increasing the temperature, density peak moved to the right and increased, and then decreased when the temperature rose to a certain value. The density peak moved to the right at the low shear rate while decreased at the high one. During simulation, the high viscosity related to the low diffusion rate, which made it difficult to form a large continuous phase.
文摘Despite advancements in computational resources,the discrete element method(DEM)still requires considerable computational time to solve detailed problems,especially when it comes to the large-scale models.In addition to the geometry scale of the problem,the particle shape has a dramatic effect on the computational cost of DEM.Therefore,many studies have been performed with simplified spherical particles or clumps.Particle scaling is an approach to increase the particle size to reduce the number of particles in the DEM.Although several particle scaling methods have been introduced,there are still some disagreements regarding their applicability to certain aspects of problems.In this study,the effect of particle scalping on the shear behavior of granular material is explored.Real granular particles were scanned and imported as polygonal particles in the direct shear test.The effect of particle size distri-bution,particle angularity,and the amount of scalping were investigated.The results show that particle scalping can simulate the correct shear behavior of the model with significant improvement in computational time.Also,the accuracy of the scalping method depends on the particle angularity and particle size range.
