Application of Modified Power Law and Arrhenius Relationship in Studying Rheological Behavior of Bio-Oils

2006 ◽  
Vol 517 ◽  
pp. 147-152 ◽  
Author(s):  
W.S. Wan Nik ◽  
S.G. Eng Giap ◽  
H.H. Masjuki ◽  
H.B. Senin
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Power Law ◽  
Corn Oil ◽  
Flow Behavior ◽  
Type Equation ◽  
Power Law Model ◽  
Flow Behavior Index ◽  
Different Temperatures ◽  
Modified Power Law

Tribological aspects of bio-oils have to be investigated before they are used as industrial fluids. In this paper rheological (fluid deformation under shear) properties of four bio-oils are presented. A Couette type viscometer was used to evaluate flow behavior of the oils at seven discrete temperatures. Commercial coconut, canola, sunflower and corn oil were used in this study. For all the oil samples, viscosities were affected by the change of shear rate and temperature. Two rheological models, temperature dependence and shear rate dependence, were used in the study. The original power law gives contradict picture of flow curves and flow parameters. Thus, modified power law model was proposed. The modified model was fitted to experimental data to obtain the flow behavior index. Arrhenius type equation was fitted to experimental data to obtain the activation energy due to different temperatures and shear rates. Evaluation of rheological properties by modified power law model indicates that these bio-oils belong to the pseudo-plastic group.

The Rheological Properties of Turkish Delight

2009 ◽  
Vol 6 (1) ◽  
Author(s):  
Zurriye Yilmaz ◽  
Mehmet Dogan ◽  
Mahir Alkan ◽  
Serap Dogan
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Power Law ◽  
Food Industry ◽  
Arrhenius Equation ◽  
Flow Behavior ◽  
Effect Of Temperature ◽  
Flow Properties ◽  
Different Temperatures ◽  
Dependent Flow

In the food industry, rheological properties, such as viscosity, shear rate, and shear stress, are the most important parameters required in the design of a technological process. Therefore, in this study, we determined the flow behavior and the time-dependent flow properties of Turkish Delight (TD) in the temperature range of 25-75°C using a capillar rheometer. The structure and thermal properties of TD were investigated by XRD and a simultaneous DTA/TG analysis. The shear rate values ranged from 5 to 300s-1. We found that: (i) TD behaved as non- Newtonian pseudoplastic foodstuff; (ii) while the measurement temperature increased, viscosity decreased; and (iii) TD was a rheopectic material. The effect of temperature on viscosity was described by means of the Arrhenius equation. The activation energies for the flow of pseudoplastic TD varied from 50.1-74.2 kJ/mol, depending on shear rate. Three models were used to predict the flow behavior of TD, namely, the Power law, Bingham and Casson models. The Power law model adequately described well the flow behavior of TD at different temperatures.

Rheological investigations of water-soluble polysaccharides extracted from Moroccan seaweed Cystoseira myriophylloides algae

2020 ◽  
Vol 11 (3-4) ◽  
pp. 49-63
Author(s):  
Soumia Zaim ◽  
Omar Cherkaoui ◽  
Halima Rchid ◽  
Rachid Nmila ◽  
Reddad El Moznine
Keyword(s):  
Rheological Properties ◽  
Power Law ◽  
Flow Behavior ◽  
Viscoelastic Behavior ◽  
Shear Thinning ◽  
Water Soluble ◽  
Flow Behavior Index ◽  
Dynamic Rheological Properties ◽  
Different Temperatures ◽  
Tan Δ

The rheological properties and spectrum infrared of polysaccharides extracted from Cystoseira myriophylloides algae were investigated in the concentrations range from 3 to 9% (w/v) and at different temperatures. Results of rheological characteristics in a steady shear rate showed pseudoplastic properties and the dynamic rheological properties showed a fluid-like viscoelastic behavior. The flow and viscoelastic characteristics of polysaccharides were described using the power-law (the Ostwald model). The values of flow behavior index of the sample were close to unity (0.91) for 3% and it decreased up to 0.71 for 9% revealing the shear-thinning (pseudoplastic) nature of these polysaccharides. Moreover, the consistency coefficient increased non-linearly with concentration and it was described by a power law. The flow behavior as a function of temperature was satisfactorily described using the Arrhenius law and the activation energy values were extracted. It decreased from 15.68 and 17.21 kJ/mol when the concentration increased from 5 to 9% (w/v). Additionally, in dynamic rheological measurements, tan δ > 1 and G″ > G′ reveling a shear-thinning behavior. Finally, the analysis of the FTIR spectra of these polysaccharides showed the presence of uronic acid groups. This behavior would suggest that polysaccharides extracted from Cystoseira myriophylloides could be an interesting additive as thickeners.

scholarly journals Rheological and functional properties of Roselle (Hibiscus sabdariffa) leaves puree

10.5219/929 ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 46-57
Author(s):  
Jaga Mohan Meher ◽  
Bidyut Mazumdar ◽  
Amit Keshav
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Flow Behavior ◽  
Hibiscus Sabdariffa ◽  
Temperature Level ◽  
Flow Behavior Index ◽  
Rheological Models ◽  
Rheological Analysis ◽  
Ir Analysis ◽  
Behavior Index

Pureed form of leaves (Hibiscus sabdariffa L. (Roselle)) was taken for physicochemical and rheological analysis at temperatures and TSS range of 278 K - 318 K and 3 - 5 °Brix respectively. The steady-state rheological analysis was performed with a shear rate of 1 - 100 s-1. Different rheological models are tried; Power-law was best fitted with the experimental data (R2 ≥0.98). Temperature dependence of viscosity was found out using an Arrhenius-type relationship at a shear rate of 10, 50, 100 s-1 IR analysis was done to know the influence of functional groups on rheological properties of purees. Consistency index (K) of puree increases with increase in TSS content but at a fixed TSS, there is a decrease in K with an increase in temperatures but the opposite was observed for flow behavior index (n). Puree showed a shear thinning behavior with an increment in temperature level and puree having 5 °Brix (8.37) has higher activation energy (kJ.mol-1) than 3 °Brix (6.32).  

Static Rheological Study of Ocimum basilicum Seed Gum

2015 ◽  
Vol 11 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Fakhreddin Salehi ◽  
Mahdi Kashaninejad
Keyword(s):  
Power Law ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Power Law Model ◽  
Rotational Viscometer ◽  
Flow Behavior Index ◽  
Consistency Coefficient ◽  
Salt Addition ◽  
Seed Gum ◽  
Behavior Index

Abstract A rotational viscometer was used to investigate the effect of different sugars (sucrose, glucose, fructose and lactose, 1–4% w/w) and salts (NaCl and CaCl2, 0.1–1% w/w), on rheological properties of Basil seed gum (BSG). The viscosity was dependent on type of sugar and salt addition. Interactions between BSG gum and sugars improved the viscosity of solutions, whereas the viscosity of the BSG solutions decreased in the presence of salts. Power law model well-described non-Newtonian shear thinning behavior of BSG. The consistency index was influenced by the sugars and salts content. Addition of sucrose, glucose, lactose and salts to BSG led to increases in flow behavior index (less shear thinning solutions), whereas fructose increased shear thinning of solutions. Flow behavior index values of the power law model vary as follows: 0.43–0.49, 0.53–0.64, 0.21–0.26, and 0.57–0.67 for sucrose, glucose, fructose and lactose, respectively. The consistency coefficient (k) of BSG was affected by sugars and salts. It decreased from 0.14 to 0.09 Pa.sn with increasing CaCl2 from 0 to 4% w/w (20°C, 0.2% w/w BSG). The consistency coefficient values vary as follows: 0.094–0.119, 0.075–0.098, 0.257–0.484, and 0.056–0.074 for sucrose, glucose, fructose and lactose, respectively.

scholarly journals Polyconvex hyperelastic modeling of rubberlike materials

2021 ◽  
Vol 43 (7) ◽  
Author(s):  
Cyprian Suchocki ◽  
Stanisław Jemioło
Keyword(s):  
Experimental Data ◽  
Power Law ◽  
Curve Fitting ◽  
Constitutive Relations ◽  
Data Sets ◽  
Power Law Model ◽  
Stored Energy ◽  
Data Approximation ◽  
Exponential Power ◽  
Hyperelastic Models

AbstractIn this work a number of selected, isotropic, invariant-based hyperelastic models are analyzed. The considered constitutive relations of hyperelasticity include the model by Gent (G) and its extension, the so-called generalized Gent model (GG), the exponential-power law model (Exp-PL) and the power law model (PL). The material parameters of the models under study have been identified for eight different experimental data sets. As it has been demonstrated, the much celebrated Gent’s model does not always allow to obtain an acceptable quality of the experimental data approximation. Furthermore, it is observed that the best curve fitting quality is usually achieved when the experimentally derived conditions that were proposed by Rivlin and Saunders are fulfilled. However, it is shown that the conditions by Rivlin and Saunders are in a contradiction with the mathematical requirements of stored energy polyconvexity. A polyconvex stored energy function is assumed in order to ensure the existence of solutions to a properly defined boundary value problem and to avoid non-physical material response. It is found that in the case of the analyzed hyperelastic models the application of polyconvexity conditions leads to only a slight decrease in the curve fitting quality. When the energy polyconvexity is assumed, the best experimental data approximation is usually obtained for the PL model. Among the non-polyconvex hyperelastic models, the best curve fitting results are most frequently achieved for the GG model. However, it is shown that both the G and the GG models are problematic due to the presence of the locking effect.

Electroosmotic Flow of Power-Law Fluids in a Slit Microchannel

2009 ◽  
Author(s):  
Cunlu Zhao ◽  
Chun Yang
Keyword(s):  
Shear Stress ◽  
Double Layer ◽  
Power Law ◽  
Dynamic Viscosity ◽  
Electroosmotic Flow ◽  
Flow Behavior ◽  
Flow Behavior Index ◽  
Power Law Fluids ◽  
Hyperbolic Cosine ◽  
Behavior Index

Electroosmotic flow of power-law fluids in a slit channel is analyzed. The governing equations including the linearized Poisson–Boltzmann equation, the Cauchy momentum equation and the continuity equation are solved to seek analytical expressions for the shear stress, dynamic viscosity and velocity distributions. Specifically, exact solutions of the velocity distributions are explicitly found for several special values of the flow behavior index. Furthermore, with the implementation of an approximate scheme for the hyperbolic cosine function, approximate solutions of the velocity distributions are obtained. In addition, a mathematical expression for the average electroosmotic velocity is derived for large values of the dimensionless electrokinetic parameter, κH, in a fashion similar to the Smoluchowski equation. Hence, a generalized Smoluchowski velocity is introduced by taking into account contributions due to the finite thickness of the electric double layer and the flow behavior index of power-law fluids. Finally, calculations are performed to examine the effects of κH, flow behavior index, double layer thickness, and applied electric field on the shear stress, dynamic viscosity, velocity distribution, and average velocity/flow rate of the electroosmotic flow of power-law fluids.

TRANSPORT CURRENT CHARACTERISTICS OF THE TEXTURED Bi-2223 THICK FILM

1995 ◽  
Vol 09 (21) ◽  
pp. 1369-1376 ◽  
Author(s):  
Z. H. WANG
Keyword(s):  
Magnetic Field ◽  
Thick Film ◽  
Power Law ◽  
Flow Behavior ◽  
Transport Current ◽  
Transport Critical Current Density ◽  
Flux Flow ◽  
Different Temperatures ◽  
Current Characteristics ◽  
Activated Flux

The transport current characteristics of the textured Bi-2223 thick film were studied by the measurement of the voltage–current curves for different temperatures and various magnetic fields. The results show that the transitions can be fitted approximately by a power law with n-values at the low electrical field region. The n-value is observed to fall with increased applied magnetic field and temperature, and exhibits the thermally activated flux flow behavior. The activation energies U(T, H, J) derived from the V-I curves were found to follow a (n − 1)k B T × ln (J0/J). The critical temperature T c was found to follow the irreversibility line described by the function of H ∝ (1− T CH /T CO )1.47 for H//ab-plane. The temperature and magnetic field dependences of the transport critical current density follow a power law J c ~ (1−T COH /T COO )m and J c ~ H−α for H//ab-plane. The exponent m increases with increasing magnetic field, and α decreases with decreasing temperature. These indicate that the flux motion may be caused by a weak pinning potential energy.

Rheological Properties of Butia Pulp

2006 ◽  
Vol 2 (1) ◽  
Author(s):  
Charles Windson Isidoro Haminiuk ◽  
Maria-Rita Sierakowski ◽  
Giselle Maria Maciel ◽  
José Raniere Mazile Bezerra Vidal ◽  
Ivanise Guilherme Branco ◽  
...  
Keyword(s):  
Yield Stress ◽  
Apparent Viscosity ◽  
Good Description ◽  
Flow Behavior ◽  
Rheological Parameters ◽  
Concentric Cylinder ◽  
Flow Behavior Index ◽  
Different Temperatures ◽  
Stress Flow ◽  
Behavior Index

Rheological parameters of Butia pulp were determined at different temperatures using a concentric cylinder Haake Rotovisco rheometer, model RV-20, with measurement system ZA-30. Butia pulp was found to exhibit non-Newtonian, pseudoplastic behavior at all temperatures and the rheological parameters were adequately described by the Herschel-Bulkley model. Yield stress, flow behavior index, and consistency coefficient were significantly affected by temperature. The yield stress decreased exponentially with process temperature and ranged between 36.60 and 21.70 Pa. Apparent viscosity calculated through the Herschel-Bulkley model decreased with an increase in temperature. The Arrhenius model gave a good description of temperature effect on apparent viscosity of the pulp.

Non-Newtonian Natural Convection Along a Vertical Heated Wavy Surface Using a Modified Power-Law Viscosity Model

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
M. M. Molla ◽  
L. S. Yao
Keyword(s):  
Boundary Layer ◽  
Natural Convection ◽  
Shear Rate ◽  
Power Law ◽  
Leading Edge ◽  
Numerical Results ◽  
Wavy Surface ◽  
Viscosity Model ◽  
Length Scale ◽  
Modified Power Law

Natural convection of non-Newtonian fluids along a vertical wavy surface with uniform surface temperature has been investigated using a modified power-law viscosity model. An important parameter of the problem is the ratio of the length scale introduced by the power-law and the wavelength of the wavy surface. In this model there are no physically unrealistic limits in the boundary-layer formulation for power-law, non-Newtonian fluids. The governing equations are transformed into parabolic coordinates and the singularity of the leading edge removed; hence, the boundary-layer equations can be solved straightforwardly by marching downstream from the leading edge. Numerical results are presented for the case of shear-thinning as well as shear-thickening fluid in terms of the viscosity, velocity, and temperature distribution, and for important physical properties, namely, the wall shear stress and heat transfer rates in terms of the local skin-friction coefficient and the local Nusselt number, respectively. Also results are presented for the variation in surface amplitude and the ratio of length scale to surface wavelength. The numerical results demonstrate that a Newtonian-like solution for natural convection exists near the leading edge where the shear-rate is not large enough to trigger non-Newtonian effects. After the shear-rate increases beyond a threshold value, non-Newtonian effects start to develop.

Height Extrapolation of Wind Data

1985 ◽  
Vol 107 (1) ◽  
pp. 10-14 ◽  
Author(s):  
A. S. Mikhail
Keyword(s):  
Wind Speed ◽  
Power Law ◽  
Wind Data ◽  
Power Law Model ◽  
Short Term ◽  
Shape Factors ◽  
Wind Speeds ◽  
Average Wind ◽  
Modified Power Law

Various models that are used for height extrapolation of short and long-term averaged wind speeds are discussed. Hourly averaged data from three tall meteorological towers (the NOAA Erie Tower in Colorado, the Battelle Goodnoe Hills Tower in Washington, and the WKY-TV Tower in Oklahoma), together with data from 17 candidate sites (selected for possible installation of large WECS), were used to analyze the variability of short-term average wind shear with atmospheric and surface parameters and the variability of the long-term Weibull distribution parameter with height. The exponents of a power-law model, fit to the wind speed profiles at the three meteorological towers, showed the same variability with anemometer level wind speed, stability, and surface roughness as the similarity law model. Of the four models representing short-term wind data extrapolation with height (1/7 power law, logarithmic law, power law, and modified power law), the modified power law gives the minimum rms for all candidate sites for short-term average wind speeds and the mean cube of the speed. The modified power-law model was also able to predict the upper-level scale factor for the WKY-TV and Goodnoe Hills Tower data with greater accuracy. All models were not successful in extrapolation of the Weibull shape factors.

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