Average Absolute Deviation Percent Research Articles

Viscosity measurements of ortho-xylene, meta-xylene, para-xylene and ethylbenzene

The compressed liquid viscosities of ortho-xylene, meta-xylene, para-xylene and ethylbenzene were measured using a vibrating-wire viscometer at different temperatures and pressures. The measurements were performed over the temperature ranges of (273 to 373)K for o-xylene and m-xylene, (293 to 373)K for p-xylene and (253 to 373)K for ethylbenzene, at pressures from (0.1 to 30)MPa, except for ethylbenzene for which the pressure range was up to 35MPa. The combined expanded uncertainty of the reported viscosity is better than 2% with a confidence level of 0.95 (k=2). The experimental data were correlated with the empirical Andrade–Tait equation which reproduced the results with the average absolute percentage deviations of (0.25, 0.15, 0.16 and 0.23)% for o-xylene, m-xylene, p-xylene and ethylbenzene, respectively. The present results are in good agreement with most of the literature values.

Experimental measurement and thermodynamic modeling of CO2 solubility in aqueous solutions of morpholine

In the present work, new experimental data of CO2 solubility in aqueous solutions of 2, 3 and 4.5M (17.5, 26.1 and 39.16wt.%) morpholine (MOR) at two different temperatures (313.15 and 333.15K) is obtained by static method. The Deshmukh–Mather thermodynamic model is performed to calculate CO2 solubility in aqueous MOR solutions. The short-range interaction parameters between ion–ion and ion–molecule species in the activity coefficient model are considered to be function of temperature and are adjusted to experimental data. The model shows good results for the solubility calculations. The overall average absolute relative percent deviation (AAD%) for all the data points of CO2 partial pressure is 9.86%.

Experimental study and thermodynamic modeling for determining the effect of non-polar solvent (hexane)/polar solvent (methanol) ratio and moisture content on the lipid extraction efficiency from Chlorella vulgaris

In this research, organic solvent composed of hexane and methanol was used for lipid extraction from dry and wet biomass of Chlorella vulgaris. The results indicated that lipid and fatty acid extraction yield was decreased by increasing the moisture content of biomass. However, the maximum extraction efficiency was attained by applying equivolume mixture of hexane and methanol for both dry and wet biomass. Thermodynamic modeling was employed to estimate the effect of hexane/methanol ratio and moisture content on fatty acid extraction yield. Hansen solubility parameter was used in adjusting the interaction parameters of the model, which led to decrease the number of tuning parameters from 6 to 2. The results indicated that the model can accurately estimate the fatty acid recovery with average absolute deviation percentage (AAD%) of 13.90% and 15.00% for the two cases of using 6 and 2 adjustable parameters, respectively.

Thermodynamic modelling of hydrophobic interaction chromatography of biomolecules in the presence of salt

Hydrophobic interaction chromatography (HIC) is a useful method for isolation and purification of macromolecules. HIC separates proteins on the basis of surface hydrophobicity while generally retaining the activity of proteins. Aqueous mobile phases with high salt concentrations are often used to adsorb the proteins on a mildly hydrophobic support. In this research, the thermodynamic model of Chen and Sun, which predicts the adsorption isotherms of protein in presence of different type of salts, was modified by substitution the protein and salt activities in the mobile phase instead of their concentrations. In addition, model was examined for studying the adsorption of BSA, HSA, α-lactalbumin and Trypsinogen on different sepharose gels. The model parameters of Chen and Sun are adsorption equilibrium constant (KP), protein dehydration equilibrium constant (Ks), salt coefficient (α) and number of ligand binding (n). By substitution activity instead of salt and protein concentration, two other parameters (c1 and As), which related to the activity coefficients, are added to the model. The parameters of this nonlinear model are calculated by genetic algorithm (GA).The maximum average absolute percentage deviation (AAD) for the data which are obtained from the adsorption isotherm of BSA on phenyl sepharose gel, in the presence of different concentration of NaCl was 4.8%, while for Chen and Sun model, was 22.0%. Also maximum ADD for HSA, α-lactalbumin, and Trypsinogen adsorption was 7.8, 6.9, and 8.4, respectively. The results indicate that the modified model has adequate accuracy to predict protein HIC behaviour.

Compressed Liquid Viscosity Measurements of HFE-7000, HFE-7100, HFE-7200, and HFE-7500 at Temperatures from (253 to 373) K and Pressures up to 30 MPa

The compressed liquid viscosities of heptafluoropropyl methyl ether (HFE-7000), methoxy-nonafluorobutane (HFE-7100), ethoxy-nonafluorobutane (HFE-7200), and 2-trifluoromethyl-3-ethoxydodecafluorohexane (HFE-7500) were measured using a vibrating- wire viscometer over the temperature range of (253 to 373) K and at pressures from (0.1 to 30) MPa. The combined expanded uncertainty of the reported viscosity is about 2 % with a confidence level of 0.95 (k = 2). The experimental data were correlated with the empirical Andrade–Tait equation which could reproduce the results with average absolute percentage deviations of 0.44 %, 0.38 %, 0.56 %, and 0.56 %, respectively.

High-temperature, high-pressure viscosity of n-octane and isooctane

Experimental viscosity data are reported for n-octane and isooctane (2,2,4-trimethylpentane) at pressures between 4 and 242MPa and temperatures between 303 and 523K. These extreme conditions are representative of those encountered in ultra-deep petroleum formations beneath the deepwaters of the Gulf of Mexico. The measurements are performed using a windowed, variable-volume, rolling-ball viscometer. A comparison of reported viscosity values with available literature data for n-octane and isooctane covering limited pressure and temperature ranges shows that the average absolute percent deviation (AAPD) varies between 1.0% and 2.5%. The data are correlated by a non-linear surface fit as a simultaneous function of temperature and pressure that yields AAPD values of 0.6% and 0.8% for n-octane and isooctane, respectively. The viscosity data are also correlated with a model suitable for use in reservoir simulators; the free volume theory model with density values obtained from the Peng–Robinson equation of state (PR EoS), the volume-translated PR EoS (VT-PR EoS), the perturbed chain statistical associating fluid theory (PC-SAFT EoS), and the PC-SAFT EoS in which the parameters are fit to high temperature, high pressure density data (HTHP PC-SAFT EoS). If the parameters of the free volume theory model are fit with the EoS incorporated into the model, comparable results are obtained with each of the density models. However, if the parameters of the free volume theory model are first fit using experimental density data and then an EoS is incorporated into the free volume theory model, the best viscosity results are obtained with the most accurate density models, which are the HTHP PC-SAFT and VT-PR EoS.

Liquid Density of 2-Methoxyethyl Acetate, 2-Ethylhexyl Acetate, and Diethyl Succinate at Temperatures from 283.15 K to 363.15 K and Pressures up to 100 MPa

The density data for 2-ethylhexyl acetate, 2-methoxyethyl acetate, and diethyl succinate were reported. The density measurements were conducted with a high-pressure vibrating-tube densimeter over 9 isotherms at (283.15 to 363.15) K and 16 isobars at (0.1 to 100) MPa. The uncertainty of each obtained datum was estimated, and the expanded uncertainties of density measurements with a confidence level of 0.95 (k = 2) of density measurement for 2-ethylhexyl acetate, 2-methoxyethyl acetate, and diethyl succinate are 0.1 %. The experimental densities were correlated with the Tait-type equation, and the absolute average percentage deviations were 0.010 %, 0.009 %, and 0.011 % for 2-ethylhexyl acetate, 2-methoxyethyl acetate, and diethyl succinate, respectively. In addition, the isothermal compressibility and the isobaric thermal expansivity were derived from the Tait-type equation.

A developed equation for predicting the vapor pressure of C-H-O hydrocarbons

Abstract Prediction of the available vapor pressure data in the case of C-H-O hydrocarbons led to derivation and recommendation of standard equations for this property. The accuracy of vapor pressure estimations is essential because it is used as a basis to calculate the acentric factor and the thermal and equilibrium properties. In this study, an accurately developed equation for calculation of vapor pressure is presented for 213 pure C-H-O hydrocarbons as a function of reduced temperature and critical pressure. With this equation, vapor pressures have been calculated and compared with the experimental data reported in the literatures for 213 pure hydrocarbons for more than 3800 data points, and the overall average absolute percentage deviation is only 0.286%. The accuracy of the developed equation has been compared to Antoine, Wagner, and other most used equations, and the comparison indicates that the developed method provides more accurate results than other methods used in this work.

Viscometric investigation of binary, ternary and quaternary liquid mixtures: Comparative evaluation of correlative and predictive models

Transport properties provide a deep and meaningful insight of the various interactions taking place in binary and higher component liquid mixture. Literature reveals scarcity of data on ternary and higher order multicomponent liquid mixtures. Absolute viscosities of four binary, one ternary and one quaternary systems containing benzene, cyclohexane, n-hexane and n-decane at 298.15K have been evaluated. These systems have significant usage and applications in multifarious industries, viz., chemical, pharmaceutical, and petrochemical. Sixteen approaches have been employed involving empirical, semi-empirical, correlative and predictive models including McAllister 3 and 4 body, Grunberg–Nissan, Wijk, Hind, Katti-Chaudhri and Tamura–Kurata. The absolute average percentage deviations (AAPDs) have been used to compare their predictive capabilities. The modified McAllister relation, which employs the ECN approach developed for 308K, shows its versatility by proving its validity even at 298.15K.

Solubility of virgin coconut oil in supercritical carbon dioxide

The dynamic method was utilized to investigate the solubility of virgin coconut oil (VCO) in SC-CO2 at temperatures and pressures ranging from 313K to 353K and 20.7MPa to 34.5MPa, respectively. The highest solubility, 0.0408g/g, was obtained at 353K and 34.5MPa, which were the highest temperature and pressure levels used in the study. VCO solubility increases with temperature at pressures between 31.0 and 34.5MPa, while at pressures between 20.7 and 24.1MPa, VCO solubility decreases with an increase in temperature. At pressures between 27.5 and 30.5MPa, a solubility cross-over region was observed. VCO solubility data was correlated with the Chrastil and del Valle-Aguilera models. Within the range of experimental conditions, the solubility data showed a good correlation to both models, with an average absolute percent deviation (AAPD) value of 0.93 and 0.39 for the Chrastil and del Valle-Aguilera model, respectively.

Correlations for the prediction of the density and viscosity of 1-alcohols at high pressures

We present a correlation for the 1-alcohols density at high pressure based upon the Tait equation. The new equation includes a generalized correlation for the calculation of the density of 1-alcohols at atmospheric pressure and correlates the density of methanol to 1-decanol from (173.15 to 373.15)K at pressures up to 279MPa within an average absolute percentage deviation of 0.11% from the experimental density values. Also, we use this equation to obtain a model to correlate the liquid viscosities of 1-alcohols. The new model correlates the viscosity at atmospheric pressure within an average absolute percentage deviation of 2.14% from the experimental values. At high pressures (up to 423MPa), the new model correlates the viscosity of 1-alcohols (methanol through 1-hexadecanol) at temperatures from (293 to 423)K within an average absolute percentage deviation of 3.38%.

Application of SAFT‐VR Equation of State for Prediction of Thermophysical Properties of Sugar Solutions

AbstractThe thermodynamic properties of sugar solutions, which are important solutions in food industries, have been calculated. Because of the large molecules and hydrogen bonding in the water/sugar solutions, the statistical association fluid theory of variable ranged (SAFT‐VR) equation of state was used to calculate the thermodynamic properties such as water activity, solubility, vapor pressure and boiling temperature of the aqueous sugar solutions, including glucose, sucrose and fructose. The SAFT‐VR parameters were calculated using vapor pressure and density data for water and water activity data for sugars. The total average absolute deviation percentage (AAD%) for all the calculated properties was 1.93%. The results showed that the model can accurately predict the properties of the sugar solution.Practical ApplicationsSugar solutions have important roles and uses in different industries such as food production, food preservation industries, chemical feed stock, pharmaceutical industries, metabolic reactions, industrial operations and chemical processes, such as crystallization, evaporation and selective separation. For example, water activity in a solution can be used to stop deteriorative reactions. The density of the solution is important in separation processes and mixing equipment. Solubility of sugar in water is another important property in food preservation and processes such as gasification and separation. The boiling temperature of the solution is an important thermodynamic property in different industrial processes such as purification and separation processes.

Measurements of the isobaric heat capacity of pressurized liquid trans-1,3,3,3-tetrafluoropropene [R1234ze(E)] by scanning calorimetry

Isobaric heat capacity of pressurized liquid trans-1,3,3,3-tetrafluoropropene [R1234ze(E)] was measured by scanning calorimetry. The experimental system basically consists of a Calvet calorimeter (Setaram C80) and a pressure balance unit. A total of 95 data points were obtained at temperatures from 310.15 to 365.15 K and pressures up to 5.5 MPa. An empirical equation was used to correlate the experimental data with an average absolute percentage deviation of 0.18 %. Besides, a comparison was carried out between present data and literature data and three latest fundamental equations of state. Finally, saturated liquid heat capacity of R1234ze(E) was also investigated in this paper.

Isobaric heat capacities of R245fa and R236fa in liquid phase at temperatures from (315 to 365) K and pressures up to 5.5 MPa

Isobaric heat capacities of compressed liquid 1,1,1,3,3-pentafluoropropane (R245fa) and 1,1,1,3,3,3-hexafluoropropane (R236fa) were measured by scanning calorimetry. The experimental system basically consists of a calvet calorimeter (Setaram C80) and a pressure balance unit. A total of 55 data points for liquid R245fa and 52 data points for liquid R236fa were obtained at temperatures from (315 to 365)K and pressures up to 5.5MPa. The uncertainties for the heat capacity of R245fa and R236fa were estimated to be (1.8 and 1.6)%, respectively. The experimental data was correlated to an empirical equation, the form of which was decided by stepwise fit method. The average absolute percentage deviations between the data points and the equation were (0.23 and 0.10)% for R245fa and R236fa.

TU-F-CAMPUS-I-02: Validation of a CT X-Ray Source Characterization Technique for Dose Computation Using An Anthropomorphic Thorax Phantom

Purpose: To experimentally validate a rotational kV x-ray source characterization technique by computing CT dose in an anthropomorphic thorax phantom using an in-house dose computation algorithm (kVDoseCalc). Methods: The lateral variation in incident energy spectra of a GE Optima big bore CT scanner was found by measuring the HVL along the internal, full bow-tie filter axis. The HVL and kVp were used to generate the x-ray spectra using Spektr software, while beam fluence was derived by dividing the integral product of the spectra and in-air mass-energy absorption coefficients by in-air dose measurements along the bow-tie filter axis. Beams produced by the GE Optima scanner were modeled at 80 and 140 kVp tube settings. kVDoseCalc calculates dose by solving the linear Boltzmann transport equation using a combination of deterministic and stochastic methods. Relative doses in an anthropomorphic thorax phantom (E2E SBRT Phantom) irradiated by the GE Optima scanner were measured using a (0.015 cc) PTW Freiburg ionization chamber, and compared to computations from kVDoseCalc. Results: The agreement in relative dose between dose computation and measurement for points of interest (POIs) within the primary path of the beam was within experimental uncertainty for both energies, however points outside the primary beam were not. The average absolute percent difference for POIs within the primary path of the beam was 1.37% and 5.16% for 80 and 140 kVp, respectively. The minimum and maximum absolute percent difference for both energies and all POIs within the primary path of the beam was 0.151% and 6.41%, respectively. Conclusion: The CT x-ray source characterization technique based on HVL measurements and kVp can be used to accurately compute CT dose in an anthropomorphic thorax phantom.

Prediction of the critical properties of n-alkanes and their mixtures with two versions of SAFT equation of state

Two versions of statistical associating fluid theory (SAFT) equation of state (EoS), namely modified SAFT-BACK and original SAFT, were used to calculate the critical temperatures and pressures of 10 n-alkanes (from $$c_{1}$$ to $$c_{10}$$ ). The obtained results were compared with the available experimental data to assess the predictive power of these EoSs in the critical region. The absolute average percentage deviation (AAD %) of the results obtained from the modified SAFT-BACK model indicated that this EoS had a good performance in the prediction of the critical points of the n-alkanes, but the deviation resulting from the original SAFT EoS reflected the limitations of the latter EoS in representing the critical region. Moreover, the critical temperatures for binary mixtures of n-alkane were calculated using both the original SAFT and the modified SAFT-BACK models and the results were compared with the data predicted by the correlation relations. The modified SAFT-BACK model showed a very good performance, while the original SAFT model did not yield an appropriate prediction of the critical temperatures of n-alkane binary mixtures.

AN ACCURATE GENERAL METHOD TO CORRELATE SATURATED VAPOR PRESSURE OF PURE SUBSTANCES

In this study, a generalized equation is presented to calculate vapor pressure of pure substances as a function of reduced temperature, critical pressure, and acentric factor. With the presented model, vapor pressures have been calculated and evaluated with NIST data bank for 70 pure substances for about 14000 data points, and the overall average absolute percentage deviation has been only 0.783%. Also the accuracy of obtained model has been evaluated with mostly used equations and the results indicate the superiority of the proposed model against other methods used in this work.

An apparatus proposed for density measurements in compressed liquid regions at the pressures 0.1-60 MPa and the temperatures 288.15-413.15 K

In this work an apparatus for density measurements in the compressed liquid regions was presented. This installation is based on the use of the DMA HP density measuring cell and the DMA 5000 densimeter (both instruments are products of Anton Paar, Gratz, Austria). Calibration of DMA HP cell was performed by applying the classical method where a vacuum, water and n-decane were recommended to be used as calibration fluids. To test the capabilities of the set-up, the densities of n-hexane, toluene and dichloromethane were measured in the temperature interval 288.15 to 413.15 K and the pressure range 0.1-60 MPa. The obtained results were compared with the corresponding values found in the literature. Depending on the literature selected for comparison (the temperature and pressure ranges available) the average absolute percentage deviations were: for n-hexane 0.03-0.10%; for toluene 0.04-0.08% and for dichloromethane 0.02-0.03%. A deeper insight into the results of this work shows that most of them are in a good agreement with the literature values; higher discrepancies are remarked in the vicinity of the ends of the temperature and pressure ranges.

A new correlation for the prediction of refractive index and liquid densities of 1-alcohols

This paper presents a new correlation for the refractive index of 1-alcohols. The correlation relies upon a linear behavior with temperature from (293 to 353)K. This correlation uses the carbon number as a variable, and the universal constants result from curve fits of 117 experimental refractive index measurements for 1-alcohols from methanol to 1-decanol. The new equation correlates the refractive index within an average absolute percentage deviation of 0.05%. The correlation for the density also uses the temperature, the carbon number and the refractive index as variables. The new density equation correlates the density of 1-alcohols from (159 to 373)K within an average absolute percentage deviation of 0.08%. The extrapolative ability of both equations agrees with the data within the experimental error.

Measurement of Hybrid III Head Impact Kinematics Using an Accelerometer and Gyroscope System in Ice Hockey Helmets.

Helmet-based instrumentation is used to study the biomechanics of concussion. The most extensively used systems estimate rotational acceleration from linear acceleration, but new instrumentation measures rotational velocity using gyroscopes, potentially reducing error. This study compared kinematics from an accelerometer and gyroscope-containing system to reference measures. A Hybrid III (HIII) adult male anthropometric test device head and neck was fit with two helmet brands, each instrumented with gForce Tracker (GFT) sensor systems in four locations. Helmets were impacted at various speeds and directions. Regression relationships between GFT-measured and reference peak kinematics were quantified, and influence of impact direction, sensor location, and helmet brand was evaluated. The relationship between the sensor output and the reference acceleration/velocity experienced by the head was strong. Coefficients of determination for data stratified by individual impact directions ranged from 0.77 to 0.99 for peak linear acceleration and from 0.78 to 1.0 for peak rotational velocity. For the data from all impact directions combined, coefficients of determination ranged from 0.60 to 0.80 for peak resultant linear acceleration and 0.83 to 0.91 for peak resultant rotational velocity. As expected, raw peak resultant linear acceleration measures exhibited large percent differences from reference measures. Adjustment using regressions resulted in average absolute errors of 10-15% if regression adjustments were done by impact direction or 25-40% if regressions incorporating data from all impact directions were used. Average absolute percent differences in raw peak resultant rotational velocity were much lower, around 10-15%. It is important to define system accuracy for a particular helmet brand, sensor location, and impact direction in order to interpret real-world data.