scholarly journals Effects of hydrophobic CaO and SiO2 nanoparticles on Asphaltene Precipitation Envelope (APE): an experimental and modeling approach

2018 ◽  
Vol 73 ◽  
pp. 56 ◽  
Author(s):  
Yaser Ahmadi ◽  
Babak Aminshahidy
Keyword(s):  
Experimental Data ◽  
Saturation Pressure ◽  
Sio2 Nanoparticles ◽  
Asphaltene Precipitation ◽  
Modeling Approach ◽  
Different Temperatures ◽  
Nanoparticles Concentration ◽  
Onset Pressure ◽  
The Impact ◽  
Good Agreement

An experimental and modeling approach was developed in this research to investigate the effects of CO2, new synthesized CaO and commercial SiO2 nanoparticle concentrations on the Asphaltene Precipitation Envelope (APE). First, the effects of different temperatures and CO2 concentrations on asphaltene precipitation trends were observed. Second, the impact of CaO and SiO2 nanoparticle concentrations on asphaltene precipitation were observed in the presence of CO2 at different temperatures. Third, Advanced Redlich-Kwong-Soave (RKSA) equation of state (EOS) was considered to modify Multiflash (Infochem Co.) software from the aspect of entering physical characteristics of CaO and SiO2 nanoparticles as pseudo components. Fourth, the developed model was used for predicting the effects of CO2, CaO and SiO2 concentrations on APE in ranges that no experimental data existed. At constant CO2 concentration and temperature during natural depletion, asphaltene precipitation increased above saturation pressure, while below saturation pressure, asphaltene precipitation decreased (solution gas evolved from crude oil and made it richer). As temperature increased at constant CO2 concentration, asphaltene precipitation decreased, while it was observed that the saturation pressures increased. Although two different trends were observed in upper asphaltene onsets at different temperatures and CO2 concentrations, in wide ranges of data, as temperature increased, asphaltene upper onset pressure increased. CaO and SiO2 nanoparticles decreased asphaltene precipitations in the presence of CO2, but CaO had better applications for reducing asphaltene precipitation. The proposed Software/RKSA EOS model was in good agreement with the obtained experimental data, and it was applicable for predicting the effects of CO2, CaO and SiO2 nanoparticles concentration on APE.

Temperature Dependence of Hole Impact Ionization Coefficient in 4H-SiC Photodiodes

2009 ◽  
Vol 615-617 ◽  
pp. 311-314 ◽  
Author(s):  
W.S. Loh ◽  
J.P.R. David ◽  
B.K. Ng ◽  
Stanislav I. Soloviev ◽  
Peter M. Sandvik ◽  
...  
Keyword(s):  
Phonon Scattering ◽  
Impact Ionization ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Different Temperatures ◽  
Ionization Coefficients ◽  
Increasing Temperature ◽  
The Impact ◽  
Good Agreement ◽  
Ionization Rates

Hole initiated multiplication characteristics of 4H-SiC Separate Absorption and Multiplication Avalanche Photodiodes (SAM-APDs) with a n- multiplication layer of 2.7 µm were obtained using 325nm excitation at temperatures ranging from 300 to 450K. The breakdown voltages increased by 200mV/K over the investigated temperature range, which indicates a positive temperature coefficient. Local ionization coefficients, including the extracted temperature dependencies, were derived in the form of the Chynoweth expression and were used to predict the hole multiplication characteristics at different temperatures. Good agreement was obtained between the measured and the modeled multiplication using these ionization coefficients. The impact ionization coefficients decreased with increasing temperature, corresponding to an increase in breakdown voltage. This result agrees well with the multiplication characteristics and can be attributed to phonon scattering enhanced carrier cooling which has suppressed the ionization process at high temperatures. Hence, a much higher electric field is required to achieve the same ionization rates.

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

2021 ◽  
pp. 204141962110377
Author(s):  
Yaniv Vayig ◽  
Zvi Rosenberg
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Dynamic Pressure ◽  
Oblique Impacts ◽  
Simulation Results ◽  
The Impact ◽  
Penetration Depths ◽  
Resistance To Penetration ◽  
Good Agreement

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

Empirical estimation of engine-integration noise for high bypass ra-tio turbofan engines

2021 ◽  
Vol 263 (2) ◽  
pp. 4511-4519
Author(s):  
Incheol Lee ◽  
Yingzhe Zhang ◽  
Dakai Lin
Keyword(s):  
Experimental Data ◽  
Pressure Side ◽  
Empirical Estimation ◽  
Low Frequencies ◽  
High Frequencies ◽  
Turbofan Engines ◽  
Proposed Model ◽  
The Impact ◽  
Bypass Ratio ◽  
Good Agreement

To investigate the impact of installation on jet noise from modern high-bypass-ratio turbofan engines, a model-scale noise experiment with a jet propulsion system and a fuselage model in scale was conducted in the anechoic wind tunnel of ONERA, CEPRA 19. Two area ratios (an area of the secondary nozzle over an area of the primary nozzle), 5 and 7, and various airframe configurations such as wing positions relative to the tip of the engine nacelle and flap angles, were considered. Based on the analysis of experimental data, an empirical model for the prediction of engine installation noise was proposed. The model comprises two components: one is the interaction be-tween the jet and the pressure side of the wing, and the other is the interaction between the jet and the flap tip. The interaction between the jet and the pressure side of the wing contributes to the noise at the low frequencies (≤ 1.5 kHz), and the interaction between the jet and the flap tip con-tributes to the noise at the high frequencies. The proposed model showed a good agreement with the experimental data.

Ab Initio Study of Clean and Hydrogen-Saturated Unreconstructed SiC{0001} Surfaces

2007 ◽  
Vol 556-557 ◽  
pp. 493-496 ◽  
Author(s):  
Alexander Mattausch ◽  
T. Dannecker ◽  
Oleg Pankratov
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Surface States ◽  
Correlation Effects ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Hubbard U ◽  
The Impact ◽  
Good Agreement

Using density functional theory, we investigate the 6H-SiC{0001} surfaces in the unreconstructed 1 × 1 and the H-passivated configuration. The strong correlation effects of the dangling bonds at the surface are treated by spin-polarised calculations including the Hubbard-U parameter. We find that the clean surfaces are semiconducting with surface states in good agreement with experimental data. The impact of the Hubbard-U is stronger on the C-terminated face. For the H-passivated surfaces we find resonances in the valence band. The antibonding C−H state is located in the upper part of the bandgap around the ¯􀀀-point.

Analysis of perforation process into concrete/metal targets by rigid projectiles

2012 ◽  
Vol 227 (7) ◽  
pp. 1454-1468 ◽  
Author(s):  
N Khazraiyan ◽  
GH Liaghat ◽  
H Khodarahmi ◽  
N Dashtian-Gerami
Keyword(s):  
Experimental Data ◽  
Numerical Modeling ◽  
Cavity Expansion ◽  
Velocity Range ◽  
Material Models ◽  
Backing Plate ◽  
Expansion Theory ◽  
Cavity Expansion Theory ◽  
The Impact ◽  
Good Agreement

In this article, a semi-analytical model has been developed for perforation of a hard projectile into a single- and two-layer concrete targets. The model is based on the dynamic cavity expansion theory and the reflection of compressive waves from the end of the concrete targets. The effect of friction coefficient is also investigated in the analysis. Numerical modeling of the problem has been performed in LS-DYNA code. Holmquist–Johnson–Cook, plastic kinematic, and rigid material models have been employed for the concrete, the backing plate, and the projectile, respectively. The impact velocity range, considered in this study, is between 300 and 800 m/s. No projectile erosion is considered in this velocity range. The analytical results of the investigation for both single- and two-layer concrete targets are in a good agreement with numerical simulations and experimental data.

Modeling Gel Break-Time in Gravel Pack Fluids as a Function of Breaker and Activator Concentrations with Temperature

2011 ◽  
Vol 367 ◽  
pp. 439-448
Author(s):  
U.U. Akonye ◽  
Ogbonna F. Joel
Keyword(s):  
Experimental Data ◽  
Microsoft Excel ◽  
The Past ◽  
Time Prediction ◽  
Different Temperatures ◽  
Break Time ◽  
Experimental Values ◽  
Gravel Pack ◽  
Design And Testing ◽  
Good Agreement

Break time results carried out for 60Ibs/Mgal linear gel at different breaker and activator concentrations with temperatures for gravel pack jobs done in the past was used in this study. Temperature range investigated was from 180oF to 215oF. A mathematical model was developed for break time prediction as a function of temperature and breaker/activator concentrations. The model was regressed with experimental data using the regression tool in Microsoft Excel. Results of the model prediction were validated with experimental data. The model break time predicted showed good agreement with experimental values with less than 2% deviation. The model equation developed will help predict the break time at the various breaker and activator concentrations at different temperatures. This will help in saving time associated with the rigour in actual laboratory experimental design and testing. This will no doubt improve operational efficiency and service quality delivery.

DISPERSANT EFFECTIVENESS ON OIL SPILLS – EMPIRICAL CORRELATIONS

2008 ◽  
Vol 2008 (1) ◽  
pp. 801-804
Author(s):  
Kavitha R. Nagarajan ◽  
Niranjan Deshpande ◽  
George A. Sorial ◽  
James W. Weaver
Keyword(s):  
Experimental Data ◽  
Crude Oil ◽  
Oil Spills ◽  
Refined Oil ◽  
Mixing Energy ◽  
Oil Slick ◽  
Different Temperatures ◽  
Dispersant Effectiveness ◽  
The Impact ◽  
Full Factorial

ABSTRACT When a dispersant is applied to an oil slick, its effectiveness in dispersing the spilled oil depends on various factors such as oil properties, wave mixing energy, temperature of both oil and water, and salinity of the water. Estuaries represent water with varying salinities. In this study three salinity values in the range of 10–34 ppt were investigated, representing potential salinities found in typical estuaries. Three oils were chosen to represent light refined oil, light crude oil and medium crude oil. Each oil was tested at three weathering levels to represent maximum, medium and zero weathering. Two dispersants were chosen for evaluation. A modified trypsinizing flask termed the ‘Baffled Flask’ was used for conducting the experimental runs. A full factorial experiment was conducted for each oil to investigate the effect of salinity (3 levels), temperature (6 levels), oil weathering (3 levels) and mixing energy (150, 200, and 250 rpm) on dispersant effectiveness. Each experiment was replicated four times in order to evaluate the accuracy of the test. Statistical analyses of the experimental data were performed separately for each of the three oils three times (with or without dispersant). Viscosity of the three oils at the different temperatures and weathering conditions were determined. An empirical correlation of the viscosity for each of the three oils was then obtained. A linear regression model incorporating the viscosity correlations to represent temperature and weathering, the other remaining main factors (salinity and flask speed) and second order interactions among the factors was developed and was found to accurately represent the experimental data. The empirical approach to the interaction between the dispersant and oil slick developed could provide a useful or practical approach for including dispersants in a model to assess the impact of dispersant usage on oil spills.

scholarly journals The temperature dependence of the zeta potential in porous media

2017 ◽  
Vol 33 (4) ◽  
Author(s):  
Luong Duy Thanh
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Theoretical Model ◽  
Zeta Potential ◽  
Main Trend ◽  
Published Data ◽  
Average Increase ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Good Agreement

The measurements of the zeta potential of five consolidated samples including natural and artificial ceramic rocks saturated with 5.0×10-3 M NaCl electrolyte at different temperatures have been reported. The zeta potential obtained in this work is always negative and increases in magnitude with increasing temperature for all samples (an average increase of the zeta potential of 0.4 mV/ oC in magnitude). The experimental results are in good agreement with previously published data. The experimental data is then explained by a theoretical model. It is shown that the model is able to reproduce the main trend of the experimental data from our work and from published articles.

The influence of blanching pretreatments on the quality of dehydrated broccoli stems/ Influencia del tipo de escaldado en la calidad de tallos de bróculi deshidratados

2000 ◽  
Vol 6 (3) ◽  
pp. 227-234 ◽  
Author(s):  
N. Sanjuan ◽  
J. Benedito ◽  
G. Clemente ◽  
A. Mulet
Keyword(s):  
Experimental Data ◽  
Diffusion Equation ◽  
Product Quality ◽  
Chlorophyll Content ◽  
Improve Product Quality ◽  
Chemical Additive ◽  
Different Temperatures ◽  
High Chlorophyll Content ◽  
Good Agreement

Different blanching treatments were applied to sliced broccoli stems prior to dehydration in order to improve product quality. The pretreatments used were a conventional blanching in water at 100°C, and a stepwise blanching using different temperatures for the first step (50, 55, 60, 65 and 70°C). Five rehydration temperatures were used (25, 40, 55, 65 and 80 °C). Rehydration rate, chlorophyll content and texture of the rehydrated product were evaluated. Rehydration was modeled based on Fick's diffusion equation. A good agreement between the model and the experimental data was obtained when D eff and W e values were identified for each temperature (average percent variation 99.3). Samples stepwise blanched at 60 °C showed, on average, the lowest We and Ea values. Stepwise blanching at 60 and 65 °C and rehydration at 25, 40 and 55 °C were the combinations that gave the firmest product. Stepwise blanching at 50 °C and rehydration between 25 and 65 °C was the combination that preserved the highest chlorophyll content. From these results, it seems difficult to obtain firm samples with high chlorophyll content without any chemical additive.

Prediction of Steel Transformation Temperatures Using Thermodynamic Modeling and Design of Experiments (DOE)

2018 ◽  
Vol 941 ◽  
pp. 2284-2289
Author(s):  
Abdelhalim Loucif ◽  
Heithem Touazine ◽  
Mohammad Jahazi
Keyword(s):  
Experimental Data ◽  
Design Of Experiments ◽  
Maximum Error ◽  
Simple Approach ◽  
Alloying Element ◽  
Transformation Temperatures ◽  
Combined Use ◽  
The Impact ◽  
Liquidus Temperatures ◽  
Good Agreement

This paper presents a methodology in order to predict A1, solidus and liquidus temperatures using a relatively simple approach. The proposed approach is based on the combined use of the thermodynamic software Thermo-Calc and the composite centered design of experiments (DOE) method. Four important alloying elements (C, Ni, Mn and Cr) were considered in the DOE. The impact of each alloying element on the transformation temperatures was determined and discussed. It was found that carbon has the most important impact on solidus and liquidus whereas Ni, Mn, and Cr have a significant impact on A1. The proposed models were generated using Analysis of Variance (ANOVA) method. A good agreement between experimental and predicted results was found with a maximum error of 1.1 % for transformation temperatures. Furthermore, the proposed models were validated using a large amount of experimental data published in the literature with a maximum error equal to 7.8 %.

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