scholarly journals Non-Isothermal Models to Determine the Rheological Constants of Different Kuwaiti Crude Oils

2021 ◽  
Author(s):  
Bader Albusairi ◽  
◽  
Adam Al-Mulla ◽  
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Crude Oils ◽  
Rheological Characteristics ◽  
Exponential Factor ◽  
Empirical Relations ◽  
Eyring Equation ◽  
Statistical Estimations

The rheological characteristics of four Kuwaiti crude oils samples collected from four different collection points; namely, MG 23T, MG 29T, MG 34T and MG 108T were investigated. The investigation were conducted in the temperature range 298–313 K using the Bingham, Ostwald–de Waele, Herschel–Bulkley, Casson, and modified Casson models. The experimental data of the shear stress were modeled as a function of the shear rate and temperature. Statistical estimations were used to determine the most accurate model and non-isothermal empirical relations. The Ostwald–de Waele and Herschel–Bulkley models yielded the most accurate predictions for MG 23T, MG 29T and MG 108T, and MG 34T, respectively. It is noted that all the crude oils follow shear thinning behavior. Arrhenius-Eyring equation has been used to estimate the activation energy and the pre-exponential factor of these crude oils at a shear rate of 10.3 s-1.

Investigation on the Rheological Behavior of Polyamide6/Montmorillonite Nanocomposites by Reactive Extrusion

2011 ◽  
Vol 233-235 ◽  
pp. 1998-2001 ◽  
Author(s):  
Ming Zhao ◽  
Xiao Zhong Lu ◽  
Kai Gu ◽  
Xiao Min Sun ◽  
Chang Qing Ji
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Rheological Behavior ◽  
Reactive Extrusion ◽  
Shear Thinning ◽  
Experimental Results ◽  
Montmorillonite Nanocomposites

The rheological behavior of PA6/montmorillonite(MMT) by reactive extrusion was investigated using cone-and-plate rheometer. The experimental results indicated that PA6/MMT exhibited shear-thinning behavior. The shear stress of both neat PA6 and PA6/MMT increased with the increase in the shear rate. The reduction of the viscous activation energy with the increase of shear stress reflected PA6/MMT can be processed over a wider temperature.

ENTROPY INFLUENCE ON THE DEPENDENCE OF THE NANOFLUIDS VISCOSITY ON TEMPERATURE AND SHEAR RATE

2021 ◽  
Vol 7 (3) ◽  
pp. 89-105
Author(s):  
Lyudmila P. SEMIKHINA ◽  
Daniil D. Korovin
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Viscous Flow ◽  
High Reliability ◽  
Narrow Particle Size Distribution ◽  
Disperse Systems ◽  
Rotational Viscometer ◽  
Surfactant Micelles ◽  
Dispersed Systems

A Brookfield DV-II + Pro rotational viscometer was used to study the viscosity of 7 samples of concentrated nanodispersed systems (nanofluids) with a similar viscosity (6-22 mPa ∙ s), the particles of the dispersed phase in which are nanosized surfactant micelles and conglomerates from them. It was found that for 5 out of 7 studied reagents, there is a decrease in viscosity typical for dispersed systems with an increase in the shear rate, and their flow curves, that is, the dependence of the shear stress on the shear rate, correspond to the ideal plastic flow of non-Newtonian fluids. Moreover, with high reliability, R2 ≥ 0.999 is described by the Bingham equation with a small value of the limiting shear stress (less than 0.2 Pa). It is shown that all the studied reagents are also characterized by an increase in the activation energy of a viscous flow Е with an increase in the shear rate. As a result, a decrease in viscosity with an increase in shear rate, typical for disperse systems, including nanofluids, is provided by a more significant increase in entropy changes ΔS compared to Е. It has been substantiated that, depending on the ratio between the activation energy of viscous flow Е and the change in entropy ΔS, the viscosity of concentrated micellar dispersed systems with an increase in the shear rate can decrease, remain unchanged, and increase. The last two cases, not typical for disperse systems and nanofluids, were identified and studied using the example of two demulsifiers, RIK-1 and RIK-2, with a maximum of a very narrow particle size distribution at 160 ± 5 nm, corresponding to the size of a special type of very stable micelles Surfactant — vesicle.

Methods and results of static shear stress study of Timan-Pechora Province waxy crude oils using a controlled shear rate rheometer

2018 ◽  
pp. 18-25
Author(s):  
V.O. Nekuchaev ◽  
◽  
А.Y. Lyapin ◽  
M.M. Mikheev ◽  
◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Crude Oils ◽  
Waxy Crude ◽  
Stress Study ◽  
Waxy Crude Oils ◽  
Static Shear

scholarly journals Kinetic Parameters for the Thermal Decomposition of Forest Waste Using Distributed Activation Energy Model (DAEM)

2017 ◽  
Vol 19 (1) ◽  
pp. 15-32 ◽  
Author(s):  
Alok Dhaundiyal ◽  
Pramod Tewari
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Asymptotic Expansion ◽  
Nitrogen Atmosphere ◽  
Energy Model ◽  
Pine Needle ◽  
Distributed Activation Energy Model ◽  
Exponential Factor ◽  
Forest Waste

Abstract The purview of paper pivoted around the pyrolysis decomposition of forest waste (pine needle litter) by thermogravimetric analysis (TGA). Experiments were carried out in the presence of Nitrogen atmosphere. The experimental data was compared with those obtained by numerical solution of distributed activation energy model (DAEM). Asymptotic expansion is adopted to evaluate the pre-exponential factor, mean activation energy and variance. The correction factor Bi has been invoked to describe accurately the differential thermogravitmeric curves of thermal decomposition of pine needles.

Rheological Properties of Cooking Creams: Effect of Freeze-Thaw Treatment

2007 ◽  
Vol 3 (3) ◽  
Author(s):  
Angeles Cancela ◽  
Rocio Maceiras ◽  
Nathalie Delgado-Bastidas ◽  
Estrella Alvarez
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Frozen Storage ◽  
Rheological Behaviour ◽  
Rheological Characteristics ◽  
Concentric Cylinder ◽  
Freeze Thaw ◽  
Rheological Measurements ◽  
Treated Sample ◽  
Freezing Cycle

Rheological characteristics of commercial creams were investigated at different freeze-thaw conditions. This study was carried out to determine the effect of the freeze-thaw treatment on rheological behaviour and the activation energy in different commercial creams. Freeze-thaw treatment was made at different times of frozen storage within a range from 0 to 6 weeks. For each freezing cycle, the sample was submitted to rheological measurements within range of temperature between 20 and 40° C. A rotational, concentric cylinder viscosimeter Viscotester VT550 (Germany) type Searle was used in this work. The apparent viscosity is defined as the ratio of shear stress and shear rate, which was varied between 17.8 and 445 s-1. The Power Law or Oswaltd Waele model describes well the rheological behaviour of the analyzed samples. Furthermore, in all cases sample viscosity increased when was exposed to freeze-thaw treatment with respect to the not treated sample. And other hand, the activation energy has high values; hence there is clear evidence that the rheological behaviour presents a high dependence with the temperature.

Modeling and Analysis of the Electrorheological Fluids (Suspension Flow) with Aligned-Structure Reformation

2012 ◽  
Vol 77 ◽  
pp. 103-107
Author(s):  
Young Wook Seo ◽  
Hyoung Jin Choi ◽  
Yong Sok Seo
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Shear Rate ◽  
Field Strength ◽  
Electrorheological Fluids ◽  
Suspension Flow ◽  
Polarization Model ◽  
Modeling And Analysis ◽  
Proposed Model ◽  
Er Fluids

A new rheological model is applied to the analysis of the behavior of electrorheological (ER) fluids. A comparison of the model’s predictions with experimental data shows that the proposed model correctly predicts the shear stress behavior both quantitatively and qualitatively. The shear stress data for the aligned particles’ structure reformation can be fitted as a function of shear rate with the new model. The yield stress was found to be almost linearly dependent on the field strength, different from the predictions of the polarization model.

scholarly journals Processing the Vane Shear Flow Data from Couette Analogy

2008 ◽  
Vol 18 (3) ◽  
pp. 34037-1-34037-6 ◽  
Author(s):  
Patrice Estellé ◽  
Christophe Lanos ◽  
Arnaud Perrot ◽  
Sofiane Amziane
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Shear Rate ◽  
Shear Flow ◽  
Rotational Velocity ◽  
Rheological Behaviour ◽  
Bingham Fluid ◽  
Flow Data ◽  
Velocity Data ◽  
Torsional Flow

Abstract A new procedure is described to convert the vane torque and rotational velocity data into shear stress vs shear rate relationships. The basis of the procedure consists in considering locally the sheared material as a Bingham fluid and computing a characteristic shear rate from Couette analogy. The approach is first applied to experimental vane data of Newtonian fluid, then used to process vane experimental data of non-Newtonian and yield stress materials. Results, which are favourably compared with torsional flow, show that the approach correctly predicts the rheological behaviour of the materials investigated.

scholarly journals Modeling of Isocyanate Synthesis by the Thermal Decomposition of Carbamates

Computation ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 89
Author(s):  
Ratmir Dashkin ◽  
Georgii Kolesnikov ◽  
Pavel Tsygankov ◽  
Igor Lebedev ◽  
Artem Lebedev ◽  
...  
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Mathematical Model ◽  
Thermal Decomposition ◽  
Computer Models ◽  
Computational Experiments ◽  
Comsol Multiphysics ◽  
Suggested Model ◽  
Exponential Factor ◽  
Calculation Results

The presented work is devoted to isocyanate synthesis by the thermal decomposition of carbamates model. The work describes the existing isocyanate-obtaining processes and the main problems in the study of isocyanate synthesis by the thermal decomposition of carbamates, which can be solved using mathematical and computer models. Experiments with carbamates of various structures were carried out. After processing the experimental data, the activation energy and the pre-exponential factor for isocyanate synthesis by the thermal decomposition of carbamates were determined. Then, a mathematical model of the reactor for the thermal decomposition of carbamates using the COMSOL Multiphysics software was developed. For this model, computational experiments under different conditions were carried out. It was shown that the calculation results correspond to the experimental ones, so the suggested model can be used in the design of the equipment for isocyanate synthesis by the thermal decomposition of carbamates.

scholarly journals Comparison between different models for rheological characterization of sludge from settling tank

2017 ◽  
Vol 34 (1) ◽  
pp. 191-196 ◽  
Author(s):  
Beata Malczewska ◽  
Adrian Biczyński
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Shear Rate ◽  
Settling Tank ◽  
Coaxial Cylinder ◽  
Municipal Sludge ◽  
Rheological Characterization ◽  
Rheological Models ◽  
Bingham Plastic

Abstract The municipal sludge characterized non-Newtonian behaviour, therefore the viscosity of the sewage sludge is not a constant value. The laboratory investigation was made using coaxial cylinder with rotating torque and gravimetric concentration of the investigated sludge ranged from 4.40% to 2.09%. This paper presents the investigation on the effect of concentration of rheological sludge behaviour. The three different rheological models: Bingham (plastic model), Ostwald-de Waele (power-law), Hershel-Bulkley’s were calculated by fitting the experimental data of shear stress as a function of shear rate to these models. In this study, the 3-parameter Herschel- Bulkley’s model fits the experimental data best.

Diffusion in Partially Ion Exchanged Molecular Sieves

1974 ◽  
Vol 52 (20) ◽  
pp. 3523-3528 ◽  
Author(s):  
D. M. Ruthven
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Activation Energy ◽  
Molecular Sieves ◽  
Entire Range ◽  
Abrupt Change ◽  
Ionic Composition ◽  
Exponential Factor ◽  
Gradual Variation ◽  
Ionic Forms

Results of a simple idealized numerical simulation are presented showing the variation of sorbate diffusivity with degree of ion exchange in a system such as the Na–Ca A zeolites. Theoretical curves showing the expected variation of diffusivity, diffusional activation energy, and pre-exponential factor are given. The pattern of behavior predicted depends on the ratio of the diffusivities for the extreme ionic forms. When this ratio is small there is a gradual variation in diffusivity, activation energy, and pre-exponential factor over the entire range of ionic compositions but for large ratios there is an abrupt change at a particular ionic composition. Limited experimental data for the diffusion of n-butane in partially Ca2+ exchanged 4A sieve are presented and interpreted in terms of the theoretical model.

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