Densities and surface tensions of ionic liquids/sulfuric acid binary mixtures

The densities and surface tensions of [Bmim][TFO]/H_2SO_4, [Hmim][TFO]/H_2SO_4 and [Omim][TFO]/H_2SO_4 binary mixtures were measured by pycnometer and Wilhelmy plate method respectively. The results show that densities and surface tensions of the mixtures decreased monotonously with increasing temperatures and increasing ionic liquid(IL) molar fraction. IL with longer alkyl side-chain length brings a lower density and a smaller surface tension to the ILs/H_2SO_4 binary mixtures. The densities and surface tensions of the mixtures are fitted well by Jouyban–Acree(JAM) model and LWW model respectively. Redlich-Kister(R–K) equation and modified Redlich-Kister(R–K) equation describe the excess molar volumes and excess surface tensions of the mixtures well respectively. Adding a small amount of ILs(xILb 0.1) into sulfuric acid brings an obvious decrease to the density and the surface tension. The results imply that the densities and surface tensions of ILs/H_2SO_4 binary mixtures can be modulated by changing the IL dosage or tailoring the IL structure.

Mechanical effects of circular liquid inclusions inside soft matrix:role of internal pressure change and surface tension

The mechanical effects of dilute liquid inclusions on the solid-liquid composite are explored,based on an analytical circular inclusion model incorporating the internal pressure change of the liquid and the surface tension of the interface.Several simple explicit dependences of the stress field and effective stiffness on the bulk modulus and the size of the liquid,the surface tension,and Poisson’s ratio of the matrix are derived.The results show that the stresses in the matrix are reduced,and the stiffness of the solid-liquid composite is enhanced with the consideration of either the surface tension or the internal pressure change.Particularly,the effective Young’s modulus predicted by the present model for either soft or stiff matrices agrees well with the known experimental data.In addition,according to the theoretical results,it is possible to stiffen a soft solid by pressured gas with the presence of the surface tension of the solid-gas interface.

A NEW MODEL FOR THE SURFACE TENSION OF BINARY AND TERNARY LIQUID MIXTURES BASED ON PENG-ROBINSON EQUATION OF STATE

Based on the surface chemical potential and Peng-Robinson equation of state,a newmodel is proposed to predict and correlate the surface tensions of binary and ternary liquid mix-tures.Using this method,the surface tensions of 73 binary and 8 ternary systems are calculatedwith average relative deviations 1.35% and 3.52% respectively.The proposed model is simple, re-liable and accurate.

Prediction of Surface Tensions of Pure Liquid Metals and Alloys

The surface tensions of pure liquid metals were estimated by using the artificial neural network method. Based on Butler's equation the surface tensions of some liquid Sn-, Ag-, Cu-based binary alloys were calculated from surface tensions of pure components and thermodynamic parameters of liquid alloys using a well designed computer program with C++ language, named STCBE. The agreement between calculated values and experimental data was excellent. The surface tensions of binary liquid Cu-RE(RE: Ce, Pr, Nd) alloys at 1400 K were predicted therewith.

AN APPROACH TO CALCULATE THE SURFACE TENSION OF THE LIQUID NITROGEN FILM ON SOLIDS FROM AN ADSORPTION ISOTHERM

The equations, used in this paper to calculate the surface tension of the liquid nitrogen film formed by the physical adsorption on many different model solids (e.g. spherical partiele, plane particle and spherical cavity pores or cylindrical pores at the openings of both ends in solid bodies), have been derived on the thermodynamie principle. The calculated results have shown that the surface tension (γ) of the adsorbed liquid nitrogen film on most of non-porous solid surfaces diminishes with the rise of the nitrogen gas pressure (p) or of the adsorbed layers (n) at 77.3K; when p reaches the vapour pressure (p_s) of the bulk liquid nitrogen, y turns into the surface tension (γ_o) of the bulk liquid nitrogen; whgn p /p, 【0.98, there is an obvious difference between γ and γ_O.

Expressions of the radius and the surface tension of surface of tension in terms of the pressure distribution for nanoscale liquid threads

The expressions of the radius and the surface tension of surface of tension Rs and γs in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics （MD） simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature[Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out.

Molecular dynamics simulation of liquid-vapor surface tension

A molecular dynamics simulation model is established based on the well-known Lennard-Jones 12-6 potential function to determine the surface tension of a Lennard-Jones liquid-vapor interface. The simulation is carried out with argon as the working fluid of a given molecular number at different temperature and different truncated radius. It is found that the surface tension of a Lennard-Jones fluid is likely to be bigger for a bigger truncated radius, and tends to be constant after the truncated radius increased to a certain value. It is also found that the surface tension becomes smaller as the temperature increases.

Surface Tension and Electrostriction in a Suspended Bridge of Dielectric Liquid

The mechanism of the formation of a surprisingly long suspended liquid bridge subjected to a dc electric field has been intensively studied in the past few decades. However, the role of electrostriction and quantitative evaluation of surface tension in the bridge have not been evaluated. We present combined theoretical and experimental studies on this issue. Electrostriction is pointed out to be the driving force that pushes liquid upward against gravity and into the gap between two containers and forms the suspended bridge, which is within the framework of the Maxwell pressure tensor. Through a comparison between experiment and theory, the surface tension is found to play an important role in holding the long suspended bridge. Ignorance of the surface tension leads to much smaller bridge length than the experimental values. The dynamic stability of the bridge with respect to its diameter, length and conductance is also discussed.

Surface and transport properties of Cu-Sn-Ti liquid alloys

The lack of experimental data and / or limited experimental information concerning both surface and transport properties of liquid alloys often require the prediction of these quantities. An attempt has been made to link the thermophysical properties of a ternary Cu-Sn-Ti system and its binary Cu-Sn, Cu-Ti and SnoTi subsystems with the bulk through the study of the concentration dependence of various thermodynamic, structural, surface and dynamic properties in the frame of the statistical mechanical theory in conjunction with the quasi-lattice theory （QLT）. This formalism provides valuable qualitative insight into mixing processes that occur in molten alloys.

Heat Transfer in a Liquid-Solid Circulating Fluidized Bed Reactor with Low Surface Tension Media

Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively. Effects of liquid velocity, particle size, surface tension of liquid phase and solid circulation rate on the overall heat transfer coefficient were examined. The heat transfer coefficient increased with increasing particle size or solid circulation rate due to the higher potential of particles to contact with the heater surface and promote turbulence near the heater surface. The value of heat transfer coefficient increased gradually with increase in the surface tension of liquid phase, due to the slight increase of solid holdup. The heat transfer coefficient increased with the liquid velocity even in the higher range, due to the solid circulation prevented the decrease in solid holdup, in contrast to that in the conventional liquid-solid fluidized beds. The values of heat transfer coefficient were well correlated in terms of dimensionless groups as well as operating variables.

A Surface Tension Model for Liquid Mixtures Based on NRTL Equation

A new equation for predicting surface tension is proposed based on the thermodynamic definition of surface tension and the expression of the Gibbs free energy of the system. Using the NRTL equation to represent the excess Gibbs free energy, a two-parameter surface tension equation is derived. The feasibility of the new equation has been tested in terms of 124 binary and 16 multicomponent systems(13-ternary and 3-quaternary) with absolute relative deviations of 0.59% and 1.55% respectively. This model is also predictive for the temperature dependence of surface tension of liquid mixtures. It is shown that, with good accuracy, this equation is simple and reliable for practical use.

Substrate elastic deformation due to vertical component of liquid-vapor interfacial tension

Young＇s equation is a fundamental equation in capillarity and wetting, which reflects the balance of the horizontal components of the three interracial tensions with the contact angle （CA）. However, it does not consider the vertical component of the liquid-vapor interracial tension （VCLVIT）. It is now well understood that the VCLVIT causes the elastic deformation of the solid substrate, which plays a significant role in the fabrication of the microfluidic devices because of the wide use of the soft materials. In this paper, the theoretical, experimental, and numerical aspects of the problem are reviewed. The effects of the VCLVIT-induced surface deformation on the wetting and spreading, the deflection of the microcantilever, and the elasto.capillarity and electro- elasto.capillarity are discussed. Besides a brief review on the historical development and the recent advances, some suggestions on the future research are also provided. Key words

A New Method of Studying Surface Activity for Liquid Alloys

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Investigation of Different Ionic Liquids in Improving Oil Recovery Factor

In order to improve oil recovery, Enhanced Oil Recovery (EOR) techniques have been applied to several light and medium oil reservoirs. This research was directed towards the development of chemical flooding methods for such reservoirs. The main objective of this experimental work was to investigate the efficiency of introducing various types of Ionic Liquids (ILs), 1-Ethyl-3-methylimidazolium Chloride [EMIM][Cl], 1-Benzyl-3-methylimidazolium Chloride [BenzMIM][Cl], and Trihexyltetradecylphosphonium Chloride [THTDPh][Cl] on the Recovery Factor (RF) of medium oil (Weyburn oil, 30.25 API°) at room temperature. The series of flooding experiments were carried out by introducing a slug of IL mixtures. Results demonstrated that maximum oil recovery factor was obtained when [EMIM][Cl] was added in the displacing fluid. Further investigations have been conducted to examine the effect of ILs concentrations on the recovery mechanisms by measuring Surface Tension (SFT), pH, and viscosity of the displacing phases. Finally, the effect of theses ILs in wettability alteration was examined.

Effects of Atmospheric Pressure on Developmental Characteristics and the Stability of Air Entraining Agent for Concrete

In order to ascertain the effects of atmospheric pressure on developmental characteristics and the stability of AEA(air-entraining agent)solution bubbles,AEA solution experiments and AEA solution bubble experiments were,respectively,conducted in Peking(50 m,101.2 kPa)and Lhasa(3,650 m,63.1 kPa).Surface tensions and inflection-point concentrations were tested based on AEA solutions,whilst developmental characteristics,thicknesses and elastic coefficients of liquid films were tested based on air bubbles of AEA solutions.The study involved three types of AEAs,which were TM-O,226A,and 226S.The experimental results show that initial sizes of TM-O,226A,and 226S are,respectively,increased by 43.5%,17.5%,and 3.8%.With the decrease of ambient pressure,the drainage rate and the drainage index of AEA solution bubbles increase.Interference experiments show that the liquid film thicknesses of all tested AEA solution bubbles are in micron scales.When the atmospheric pressure decreases from 101.2 to 63.1 kPa,the liquid film thicknesses of three types of AEA solutions decrease in various degrees;and film elasticities at critical thicknesses increase.Liquid film of 226S solution bubbles is the most stable,presenting as a minimum thickness variation.It should be noted that elastic coefficient of liquid film only represents the level at critical thickness,thus it can not be applied as the only evaluating indicator of bubble stability.For a type of AEA,factors affecting the stability of its bubbles under low atmospheric pressure include initial bubbles size,liquid film thickness,liquid film elasticity,ambient temperature,etc.

Modeling of Surface Tension and Viscosity for Non-electrolyte Systems by Means of the Equation of State for Square-well Chain Fluids with Variable Interaction Range

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.

Liquid crystal model of vesicle deformation in alternating electric fields

Considering the effects of osmotic pressure, elastic bending, Maxwell pressure, surface tension, as well as flexo-electric and dielectric properties of phospholipid membrane, the shape equation for sphere vesicle in alternation （AC） electric field is derived based on the liquid crystal model by minimizing the free energy due to coupled mechanical and AC electrical fields. Besides the effect of elastic bending, the influence of osmotic pressure and surface tension on the frequency dependent behavior of vesicle membrane in AC electric field is also discussed. Our theoretical results for membrane deformation are consistent with corresponding experiments. The present model provides the possibility to further disclose the frequency-depended behavior of biological cells in the coupled AC electric and different mechanical fields.

MATERIALS FOR RETENTION OF LIQUID CRYOGENS CONTAINED IN SPACE QUALIFIED COOLER

A new kind of material used in liquid cryogen cooler has been found and investigated in our group It is anticipated that the materials can be applied in the conditions of launching, rotation in any orientation and weightlessness. The mechanism on which the material relies is similar to 'sponge' trapping the liquid cryogens within its micro-pores with surface tension. Preliminary tests have been performed on wicking. Also,we apply the materials to the cryogenic optical cooler whjch needs to be maintained within the temperuture range of 80-100 K. The results are satisfactory.