An Analytical Non-Newtonian and Nonisothermal Viscous Flow Simulation

Polymer process control is limited by a lack of observability of the distributed and transient polymer states. An analytical solution is presented for on-line simulation of non-Newtonian and nonisothermal viscous flow in real-time polymer processing. The modeling of the non-Newtonian viscous flow utilizes a modified Ellis model that expresses viscosity as a function of shear stress; the modeling of the heat transfer utilizes a Bessel series expansion to include effects of heat conduction, heat convection, and internal shear heating. The resulting simulation is suitable for inclusion in real-time process controllers requiring sub millisecond response. Numerical verification indicates that the flow rate predictions of the described analysis compare well with the results from a commercial molding simulation. However, empirical validation utilizing a design of experiments for an injection molding process indicates that the described analysis is qualitatively useful but does not possess sufficient accuracy for quantitative process and quality control.     

STEADY SHEAR FLOW PROPERTIES OF HIGH SOLIDS SOFTWOOD KRAFT BLACK LIQUORS: EFFECTS OF TEMPERATURE, SOLIDS CONCENTRATIONS, LIGNIN MOLECULAR WEIGHT AND SHEAR RATE

The steady shear flow properties of several softwood kraft black liquors (slash pine) from a two level, four variable factorially designed pulping experiment were determined for solids concentrations from 50% to 85%, temperatures from 40°C to 140°C and shear rates up to 10,000 s-1 by using Instron capillary and Haake coaxial cylinder rheometers. It was shown that the slip velocity at the wall of the capillary is insignificant and that a two capillary method can be used to determine the viscosity of the samples. At high solids, black liquor can exhibit non-Newtonian behavior dependent upon temperature, solids concentrations, solids composition and shear rate. In general, the liquors behave as pseudoplastic fluids. The exact level of viscosity at any given condition is dependent upon the solids composition which will vary from liquor-to-liquor. The flow behavior of the liquors was described using power-law, Cross and Carreau-Yasuda models. Superposition principles developed for polymer melts and concentrated polymer solutions were applied to obtain reduced correlations for viscosity behavior of the liquors. By using a suitable reference temperature, related to the glass transition temperature of black liquors, a generalized WLF type shift factor was obtained for the liquors used in this study and can be used to obtain a reduced plot of viscosity behavior of other black liquors.     

PREPARATION AND CHARACTERIZATION OF BIODEGRADABLE POLYMER MUD BASED ON MILLET STARCH

A biodegradable polymer mud was prepared using Millet starch pre-gelatinized in the absence of a solvent. The filtration and rheological properties of the mud were studied at 25°–200°C temperature range and at 0.01–0.05 g/mL concentration of starch using filter loss and viscometric methods respectively. Experimental results showed that the new mud has better filtration control behavior and thermal stability at all the temperatures than widely used mud prepared with hydroxy propyl–modified starch. The mud displayed thermal degradation at 200°C. The values of flow index were found to be less than 1.0, showing non-Newtonian and pseudoplastic flow behavior of the mud. Shear stress and yield stress increase with increase in concentration. Viscosity decreases with increasing shear rate, showing shear thinning behavior of the mud. The polymer mud obeyed Henri Darcy and API models for static filtration as well as power law and Herschel-Bulkley models for fluid rheology. The new mud is purer and more suitable for drilling operations in environmentally sensitive areas than the widely used mud.     

Synthesis,characterization and evaluation of a quadripolymer with low molecular weight as a water based drilling fluid viscosity reducer at high temperature (245 °C)

To construct an ultra‐high temperature stable drilling mud with a relatively low viscosity, a new viscosity‐reducing additive was synthesized and evaluated. This additive is a quadripolymer of acrylic acid (AA), 2‐acryl‐amido‐2‐methyl‐1‐propane sulfonic acid (AMPS), methyl acrylate (MA) and dimethyl diallyl ammonium chloride (DDAC) with low molecular weight synthesized by free radical polymerization, and its general molecular composition was confirmed by Fourier transform infrared spectroscopy. Thermal gravimetric analysis showed that the polymer has a very high temperature tolerance, i.e. it is stable up to 340 °C. Turbidity measurements with a UV?visible spectrophotometer showed that the polymer has a high salt tolerance in solution. It remained in solution at NaCl concentrations of up to 266 958 mg L^?1 and at CaCl₂ concentrations of up to 5000 mg L^?1. The quadripolymer was found to inhibit hydration of the exchangeable ions in the clay particles and this was affirmed by a reduction in interlayer spacing. It also displayed high adsorption on calcium montmorillonite at different pH and even in the presence of NaCl, and caused the breakup of the particle network structure. This additive, when added to drilling mud prepared in both fresh and salt water, was found to reduce the mud viscosity and yield stress before and after aging for 16 h at 245 °C compared to base mud especially below 220 °C and 4.5 MPa. Importantly, this additive in mud was found to perform effectively at a relatively high pH and in a broad pH range of 7–11. © 2015 Society of Chemical Industry     

ILAR中醇及电解质对非牛顿流体中气-液传质的影响

在-气升式内环流反应器中试验考察了非牛顿流体羧甲基纤维素钠(CMC)中的气泡聚并现象以及表面活性物质对液相体积传质系数的影响。结果表明,非牛顿流体中气-液传质效率随黏度的增加而降低,其原因是黏度增加使Taylor泡的尾流趋于稳定,降低了液相扰动,气泡间易聚并,从而气-液传质效率低。向非牛顿流体中添加醇类物质会影响气-液传质行为,对于聚合物含量低的流体,添加微量醇可以促进气-液传质,聚合物含量高的非牛顿流体,微量醇的加入反而不利于气-液间传质过程。非牛顿流体在ILAR上升管中的气含率随着黏度的增加变化不大,而下降管中的气含率有所提高。     

Investigation of Polymer Adsorption on Rock Surface of Highly Saline Reservoirs

Blocking or reducing water production from oil wells is a serious problem in oil industry. Two types of polymers, namely, polyacrylamide (PAA) and polysaccharides (xanthan) have been investigated in this paper. The viscosity of both polymer solutions was first evaluated at different salinities, shear rates and concentrations. Afterwards, the solutions were injected into core samples to examine the adsorption on the rock surface by calculating the resistance factor as well as the residual resistance factor. Also, the effect of the injection rate of the polymer solutions has been studied. The results show that xanthan solution is tolerant of high salinity (20 %), while PAA solution is very sensitive to salt. Both polymer solutions show a pseudoplastic flow as a function of the shear rate. The core sample experiments show that both polymer solutions suffer a reduction in the adsorption rate with salinity increase. However, xanthan shows acceptable values even with a salinity up to 20 % and a temperature of 60 °C. Therefore, xanthan can be recommended to shut off water in high salinity and high temperature reservoirs. It was also found that the lower the injection rate the higher the adsorption on the rock surface.     

Viscous properties of polymer-thickened water-in-oil emulsions

The viscous flow properties of polymer-thickened water-in-oil emulsions were measured using a coaxial cylinder viscometer. The emulsions were prepared using deionized water and polyisobutylene in oil solutions. Three different molecular weight polyisobutylenes (Vistanex MML-140, Vistanex MML-100, and Vistanex MML-80) were studied. The effects of polymer concentration and water (droplet) concentration on the flow properties were determined. The polymer concentration varied from 0 to 3.96% by weight based on the oil phase whereas the water concentration varied from 0 to 80% by volume (based on total emulsion volume). The polymer solutions behaved like non-Newtonian Ellis model fluids. At low water concentrations, the flow curves for emulsions were similar to their suspending medium (polymer solution). At high values of water concentration, emulsions clearly exhibited a yield stress. The yield stress increased with both water and polymer concentrations. The shear stress/shear rate data for the emulsions possessing a yield stress were described adequately by a modified Herschel-Bulkley model. A comparison was also made of the relative viscosities of emulsions having different polymer concentrations. The relative vis-cosities for polymer-thickened emulsions were found to be significantly lower than the corresponding values for emulsions without polymer. The correlation of relative viscosity/ concentration data is discussed. © 1993 John Wiley & Sons, Inc.     

Rheology of oil in water emulsions with added solids

The effect of added solids on the rheology of oil in water emulsions was investigated. The range of the oil concentration, solids free basis, was (0-70%) and the solids volume fraction was (0-0.16). The solids mean diameter was 45 μm and it was about four times larger than the oil droplets. In the absence of added solids, non-Newtonian behaviour was observed for oil concentrations above 40%. The added solids increased the emulsion viscosity in a manner similar to the addition of solids to a homogeneous fluid. The rheological data of all the emulsion-solids mixtures investigated were correlated as relative viscosity versus solids volume fraction, where the relative viscosity is defined as the ratio of the emulsion-solids mixture viscosity to the solids-free emulsion viscosity. In the case of non-Newtonian systems, the emulsion-solids mixture viscosity and the solids-free emulsion viscosity were calculated at the same shear stress. The Barnea and Mizrahi viscosity correlation was found to fit the data well.     

MASS TRANSFER IN DRIPPING PLATE COLUMN FOR NON-NEWTONIAN FLUIDS

In this paper, the mass transfer for non-Newtonian liquid has been studied in a dripping plate column fitted with perforated trays. The rate of evaporation of polymer solution in the column was measured and correlated. It was found that temperature, presure, mass flow rate and the non-Newtonian behavior of the solution are the significant factors having effects on mass transfer.     

The influence of non-Newtonian flow on effective viscosity and channel efficiency in screw pumps

A method is given for selecting the “effective viscosity” for isothermal flow of non-Newtonian liquids in screw pumps or melt extruders. Effective viscosity is the Newtonian viscosity that would give the same screw-pump performance with non-Newtonian liquids at the same flow rate and speed. When effective viscosity is known, it can be inserted in performance equations for simple Newtonian flow. The analysis is restricted to shallow screw-pump channels with large aspect ratios and to shear stress/shear rate curves with modest curvatures when shown in a double logarithmic plot. The shear stress/shear rate curve is replaced by a power-law tangent to that curve in the domain of prevailing shear rates, but the analysis could be extended to more complex behavior. Curves are also included for calculating the efficiency of the screw-pump channel, which can be used to estimate the energy dissipated in screw-pumps. It is shown that efficiency decreases with decreasing power-law exponent.     

淋降塔内非牛顿流体的传质研究

本文研究非牛顿幂律流体传质过程,实验采用淋降塔装置,测定高聚物溶液的传质速率.实验结果表明传质速率随温度和溶液流量增加而增大,还随压力和溶液稠度系数下降而增加.并应用相似论原理分析非牛顿幂律流体传质过程,得到柯尔本因子与雷诺数关系式j_m=BRe~B_1,由实验数据经线性回归得到B=2.2708×10~(-5),B_1=-0.7013相关系数0.99.     

Effect of micro-aggregation behavior on the salt tolerance of polymer solutions

Polymer solution for oil displacement is mostly used in the middle and late stage of water flooding reservoir development, and reservoir groundwater conditions are often one of the main conditions restricting polymer application. Therefore, it is necessary to develop salt tolerance of polymer solutions with different aggregation behaviors, so as to facilitate the synthesis and optimization of suitable polymer systems. The differences in the micro-aggregation behavior of three polymers with different molecular structures were explored. On this basis, the effects of divalent metal cations on the properties of the polymer solutions were analyzed by assessing the micro-aggregation behavior, apparent viscosity, hydrodynamic size, and shear rheological characteristics. The results showed that the linear partially hydrolyzed polyacrylamide (HPAM) was seriously affected by divalent cations, and the viscosity decreased obviously. The aggregation behavior of the polymer changed by hydrophobic association can enhance the salt tolerance of the solution. The hydrophobically modified partially hydrolyzed polyacrylamide (HMPAM) with “chain beam” aggregation behavior has strong intermolecular connection, which enables it to withstand the content of calcium and magnesium ions of 1100 mg l⁻¹. When the content of calcium and magnesium ions exceeds 600 mg l⁻¹, dendritic hydrophobically associating polymer (DHAP) will destroy the interaction between molecular chains, resulting in the decrease of apparent viscosity and hydrodynamic size. For polymer flooding in high-salinity reservoir, salt tolerant polymer system can be constructed by optimizing molecular weight and hydrophobic group content.     

Aqueous solution properties of poly(trimethyl acrylamido propyl ammonium iodide) [poly(TMAAI)]

The aqueous solution properties of a cationic poly(trimethyl acrylamido propyl ammonium iodide) [poly(TMAAI)] were studied by measurements of reduced viscosity, intrinsic viscosity, and flocculation test. The reduced viscosity and intrinsic viscosity of this cationic polyelectrolyte were related to the types and concentration of added salt. “Soft” salt anions were more easily bound on the quaternary ammonium (R₄N⁺) of poly(TMAAI) than those of “hard” salt anions. Halide anions are hard anions; consequently, hard cations were more easily attracted to halide anions for reducing the binding degree of halide anion on the quaternary ammonium group (R₄N⁺). Some salt ions were observed to strongly attract the quaternary ammonium of the cationic polymeric side chain for coagulation of the polymers. This effect would make the polymeric aqueous solution become turbid. The intrinsic viscosity behavior for cationic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain is contrasted with polyampholyte. A comparison of various flocculants as to the effect of flocculation was also studied. © 1994 John Wiley & Sons, Inc.     

Rheology of polymer melts in high shear rate

Little is known of the rheology of polymer melts in the high shear rate up to 10⁶ s^?1 or more. A specially designed high-shear-rate rheometer was developed, by which the rheology of polymer melts for shear rates up to 10⁸ s^?1 can be investigated. Two non-Newtonian regions and a transition or the second Newtonian region were observed in the wide range of shear rates up to 10⁷ s^?1. The observed flow curves for various polymer melts are classified into three typical patterns. One is the flow curve typically shown of high-density polyethylene in which a clear second Newtonian region appears after the first non-Newtonian region. The second is the typical flow curve of polystyrene in which a “transition region” appears instead of the second non-Newtonian region. The third is the flow curve shown of acrylonitrile-styrene copolymer, which exhibits behavior between the two types. A generalized flow curve is proposed to explain the observed flow behaviors of various polymers over a wide range of shear rates. The flow behavior in high shear rate results from high orientation and scission of polymer molecules.     

Three-dimensional solidification and flow of polymers in curved square ducts

Steady three-dimensional laminar flow with and without partial solidification of an initially molten polymer in square ducts, both straight and with a 90-degree curve, was numerically studied with a version of the SIMPLE algorithm. The non-Newtonian characteristics of the fluid polymer were represented by a power-law model. The temperature variation of fluid properties was taken into account. Viscous dissipation, being significant for all flow regimes studied, provided thermal energy input which was balanced by heat transfer outward across duct boundaries. For the non-Newtonian fluid with solidification and variable viscosity, it was found that the effective heat transfer coefficient in the curved section of the square duct is larger than in a straight section; in the curved section, this coefficient is larger at the outside of the bend than at the inside. These findings are in agreement with measurements reported in the literature for similar situations. The combined mechanisms of solidification on the wall and viscous dissipation result in the possibility of two different flow rates for a specified pressure gradient. The flow channel that remains unfrozen in a curved square duct meanders within the confines of the duct much as a river meanders in its valley; the wave length of the meander is sensitive to the fluid flow rate and radius of curvature.     

The formation mechanism of asymmetric membranes

Aromatic polyamide asymmetric “skin type” membranes have been prepared by the Loeb-Sourirajan technique. Two different structures were obtained, depending on the rate of precipitation. Low precipitation rates produced membranes with sponge-like structures. These membranes usually had high salt rejections and low water fluxes. High precipitation rates produced membranes with large finger-like pores. These membranes had low salt rejections and high water fluxes. Possible mechanisms producing these two structures are discussed. It is proposed that high concentrations of polymer in the casting solution, and hence high viscosities at the point of precipitation, or a thick viscous sublayer in advance of the precipitating polymer front both favour sponge-structured membrane formation. The suggested mechanisms are supported by data showing the effect of various preparation parameters such as polymer concentration and casting solution and precipitation bath composition on membrane structure.     

水基钻井液降粘剂JNG-1的合成与性能评价

以苯乙烯磺酸钠（SSS）、丙烯酰胺（AM）和丙烯酸（AA）为原料,合成了SSS/AM/AA共聚物降粘剂,并对其在泥浆中的降粘性能进行了评价。最佳合成方案为：n（苯乙烯磺酸钠）∶n（AM）∶n（AA）=2∶1∶4,单体质量为15%,反应温度80℃,反应时间3 h,引发剂用量为2%。在此条件下,合成的聚合物降粘剂结构和预计的结构一致,具有较好的抗温能力,在盐浓度为30%的盐水泥浆中,降粘率为62.71%。     

Modified bead spring theory of dilute polymer solutions. III. Inclusion of multiple relaxation times

A previously derived constitutive equation, representing a blending of the molecular dumbbell theory and a continuum theory of anisotropic fluids, has been extended to the multidumbbell (Rouse-Zimm) case. The equation thus derived yields predictions equivalent to the Rouse-Zimm theory in small-amplitude dynamic shearing, with the exception that the introduction of an “effective molecular weight” as the concentration of polymer is increased is no longer required. In simple shearing flow, the theory predictions are far superior to those of the Rouse-Zimm model, yielding realistic non-Newtonian viscosity behavior, a positive primary normal stress difference, and a negative secondary normal stress difference. In stress relaxation following the cessation of steady shearing flow, the rate of relaxation is found to depend to the initial velocity gradient, but the effect is predicted to be too small to be observed experimentally in typical dilute polymer solutions. The effects of molecular weight, molecular weight distribution, and polymer–solvent interaction are explicitly accounted for, and in all cases the theory predictions are in excellent qualitative agreement with accepted experimental behavior.     

一串上升气泡周围流体的湍动特性(英文)

The turbulence behavior of gas-liquid two-phase flow plays an important role in heat transfer and mass transfer in many chemical processes. In this work, a 2D particle image velocimetry (PIV) was used to investigate the turbulent characteristic of fluid induced by a chain of bubbles rising in Newtonian and non-Newtonian fluids. The instantaneous flow field, turbulent kinetic energy (TKE) and TKE dissipation rate were measured. The results demonstrated that the TKE profiles were almost symmetrical along the column center and showed higher values in the central region of the column. The TKE was enhanced with the increase of gas flow and decrease of liquid viscosity. The maximum TKE dissipation rate appeared on both sides of the bubble chain, and increased with the increase of gas flow rate or liquid viscosity. These results provide an understanding for gas-liquid mass transfer in non-Newtonian fluids.