فهرست مطالب

Chemical and Petroleum Engineering - Volume:53 Issue: 1, 2019
  • Volume:53 Issue: 1, 2019
  • تاریخ انتشار: 1398/05/05
  • تعداد عناوین: 12
  • Niloufar Bahrami Panah, Iman Danaee * Pages 1-10
    The inhibition properties of synthesized imine compounds N,Nʹ-bis(2,4-dihydroxyhydroxybenzaldehyde)-1,3-Propandiimine, N, N′-bis(2,4-dihydroxypropiophenone)-2,2-dimethylpropandiimine, N,Nʹ-bis(2,4-dihydroxyacetophenone)-1,3-Propandiimine has been investigated for API-5L-X65 steel corrosion in hydrochloric acid by scanning electron microscopy, potentiodynamic polarization and impedance spectroscopy. Aqueous hydrochloric acid was applied to simulate the oil and gas well acidizing fluid. Potentiodynamic polarization studies indicated that compounds retard both the anodic and cathodic reactions through adsorption and blocking the active corrosion sites. The inhibition efficiency increased with inhibitor concentration. Electrochemical impedance spectroscopy data were studied by equivalent circuit and showed that with increasing inhibitor concentration, the resistance of charge transfer enhanced and the capacitance of double layer reduced. The measured data proposed that the inhibition efficacy was increased for inhibitor in the absence of alkyl addition. The geometrical steric hindrance offered by the alkyl groups in the imine compounds plays an important role in its corrosion inhibition properties. Scanning electron microscopy was used to study the steel surface with and without inhibitors.
    Keywords: Corrosion, Imine Compounds, Impedance, Inhibitor, Well Acidizing Fluid
  • Ahmed Zoeir *, Mahshid Reyhani, Mohammad Simjoo Pages 11-24
    Future exploitation scheme of an oil reservoir in each cycle within its production life depends on the profitability of the current extraction scenario compared with predicted recoveries that acquire with applying other available methods. In fractured reservoirs appropriate time to pass from the gas injection process into chemical enhanced oil recovery (EOR) firmly depends on the oil extraction efficiency within the gas invaded zone. Several variables including fluid characteristic, fracture network and matrix units properties, etc., impact gas-oil gravity drainage (GOGD) performance within the gas invaded zone. In this work, CMG GEM and ECLIPSE 300 were used to simulate GOGD mechanism in several 2D cross-sectional models to investigate effects of the matrix height, matrix rock type, fracture network transmissibility, and miscibility conditions on the oil extraction rate, change of average pressure and producing gas-oil ratio (GOR). Results showed that in small heights of the matrix units especially at compacted rock types, GOGD was weak that caused a rapid decrease in oil production rates and early increase in producing GOR. Results also showed that wherever the matrix porosity and permeability values were high, recovery was accelerated and GOR remained constant for longer exploitation times. Furthermore, using high-pressure lean gas injection for miscible GOGD gives higher extraction efficiencies rather than applying rich or enriched gas.
    Keywords: Fractured Reservoir, Gas Invaded Zone, Miscible GOGD, CMG GEM, ECLIPSE 300
  • Behrouz Raei *, Sayyed Mohsen Peyghambarzadeh Pages 25-36
    Heat transfer coefficient and thermal efficiency of γ-Al2O3/water nanofluids flowing through a double tube heat exchanger were experimentally investigated. The nanoparticles were well dispersed in distilled water at 0.05–0.15 %vol. A large number of experiments were performed at different fluid flow rates under turbulent flow regime (18,000<Re<40,000) and various nanofluid inlet temperatures ranging from 45 °C to 65 °C. The heat transfer coefficients were measured along the length of the heat exchanger. Results showed that the local heat transfer coefficients have an asymptotic behavior. Furthermore, the addition of these small amounts of nanoparticles to the base fluid augmented the heat transfer up to 16% at the best conditions. In the end, the thermal performance factor was calculated to find the optimum condition at which the nanofluid was used. It was shown that the thermal performance factor of this nanofluid could reach to 1.11. This value was obtained at the nanoparticle concentration of 0.15 vol.% and Reynolds number 18000
    Keywords: Experimental, Friction factor, Heat transfer, Nanofluid, Reynolds Number
  • Somayeh Alijani *, Mohammad Vaez, Abdolsamad Zarringhalam Moghaddam Pages 37-51
    In the present study, a new step-based photoreactor was presented to investigate the degradation of Acid Red 73 under visible light irradiation. Four N-TiO2-coated alumina foams prepared by the modified sol-gel process were arranged in each step as photocatalyst. The experimental design methodology was employed to assess the interaction between the operational parameters in the step-based photoreactor. The effect of the initial dye concentration and the dipping time of the support on degradation efficiency is highly significant. The optimal values were found to be a flow rate of 587.96 mL/min, an initial dye concentration of 5.82 mg/L, an H2O2 concentration of 1.26 mg/L and the dipping time of 43 min. The 94% reduction in the chemical oxygen demand (COD) value indicated the effective mineralization of organic reactants of the solution. The kinetics analysis shows that the photocatalytic removal of Acid Red 73 in such photoreactor follows a first-order model. It was also shown that the proposed modified photoreactor could improve the degradation efficiency compared to the conventional step photoreactor. Results indicate that there is a potential to develop thin film coatings integrated into this new step-based photoreactor, allowing an effective photocatalytic process.
    Keywords: Immobilization on Alumina Foam, N-TiO2-P25 Nanoparticles, Response Surface Methodology, Step-Based Photoreactor, Wastewater Treatment
  • Amir Hossein Saeedi Dehaghani *, Saeed Karami, Mahdi Golriz Pages 53-62
    Rotational drilling was a revolution in drilling technology. It made the drilling process more efficient and faster and more depth of well could be achieved through rotation method. Besides all of its advantages, the rotation approach induced some problems like pipe sticking and downhole cleaning to the drilling procedure. Hole cleaning and reduction of torque and drag seems to be vital in inclined and horizontal ones due to its complexity and inclination. In this manuscript, hydraulic, torque and drag analysis were surveyed to investigate whether the path proposed for a well in the south of Iran is adequate or not. The required information was provided from associated drilling company and the proposed well trajectory used with hydraulic and drag data to run simulations via drilling office software. Effective axial load, Interaction of well and drill string, Comparison of stresses and von Mises graph were reported. Mentioned graphs showed the consistency of drilling project. The sensitivity of pressure drop to the pump flow rate and critical required rate to clean up annulus also reported pressure drop through the drilling system and required flow rate to clean up the bottom hole. In another word, obtained results of drag and hydraulic showed the consistency of trajectory.
    Keywords: Hydraulics, Torque, Drag analysis, Drilling office, Von Mise graphs
  • Seyed Foad Mousavi, Seyed Hassan Hashemabadi * Pages 63-71
    Ultrasonic transducers play a significant role in generating and receiving the acoustic waves in ultrasonic flowmeters. Depending on the required accuracy, the ultrasonic transducers can be installed either in one pair or more in an ultrasonic flowmeter. The main part of an ultrasonic transducer is its piezoceramic element. In this work, four piezoceramic elements with different diameter to thickness ratio were fabricated and one of them with center frequency of 200 kHz was selected for the numerical simulations. The piezoceramic element and its gaseous propagation environment were simulated numerically using the finite element method. Similar to the experiments, air was considered as the propagation medium and PZT-5H was used as the piezoceramic element. The results showed that the numerical simulation is in good agreement with the experimental data which indicates that numerical simulation could be an efficient alternative way to reduce trial and errors. It leads to good results if reasonable assumptions are used.
    Keywords: Experimental Fabrication, PZT-5H, Simulation, Ultrasonic Flowmeter, Ultrasonic Transducers
  • Hossein Mahmoodi Darian * Pages 73-80
    In the present work, a framework is developed for implementation of finite difference schemes on Graphic Processing Units (GPU). The framework is developed using the CUDA language and C++ template meta-programming techniques. The framework is also applicable for other numerical methods which can be represented similar to finite difference schemes such as finite volume methods on structured grids. The framework supports both linear and nonlinear finite difference stencils. Furthermore, the arithmetic operators and math functions are overloaded to ease the array-based computations on GPUs. The reduction algorithms are also efficiently included in the framework. The discharge process of a lead-acid battery cell is simulated using the facilities provided by the framework. The governing equations are unsteady and include two nonlinear diffusion equations for solid (electrode) and liquid (electrolyte) potentials and three transient equations for acid concentration, porosity and the state of charge. The equations are discretized using the finite volume method. The framework allows the user to develop the numerical solver with a few efforts. The numerical simulation results are reported for different relations for open circuit potential and the electrolyte diffusion coefficient
    Keywords: CUDA, Discharge Process, Finite Difference Method, Finite Volume Method, Graphics Processing Units, Lead-Acid Battery
  • Somayeh Jafari, Hasan Khaleghi *, Reza Maddahian Pages 81-90
    In this research, the results of comparative analysis of a single fuel droplet evaporation models are presented. Three well-known evaporation models including Spalding, Borman-Johnson and Abramzon-Sirignano models are analyzed using Computational Fluid Dynamic (CFD). The original Spalding model is extended to consider the effects of the Stefan flow, unsteady vaporization, and variable properties. The evaporation models are validated using already existing experimental data. Numerical results show that the Spalding model overestimates the temperature of the droplet surface in comparison with the other two models, although some modifications were made in the aforementioned model. Our final evaluation concludes that Abramzon-Sirignano model predictions are in good agreement with the experimental data. Therefore, in this paper, this model is used for the parametric study of the effects of droplet size, ambient temperature and pressure on the droplet lifetime and temperature. Results indicate that by increasing the droplet size, the lifetime of the droplets will increase and the steady-state droplet temperature is higher at higher ambient pressures and temperature.
    Keywords: Computational Fluid Dynamics, Droplet, Vaporization
  • Mohammad Reza Rasaei *, Fahime Firoozpour Pages 91-100
    Simulating fluid flow at micro level is an ongoing problem. Simplified macroscopic flow models like Darcy’s law is unable to estimate fluid dynamic properties of porous media. The digital sample reconstruction by high resolution X-ray computed tomography scanning and fluid-dynamics simulation, together with the increasing power of super-computers, allow to carry out pore-scale simulations through digitally-reconstructed porous samples. The pore-scale flows which derived from computational fluid dynamic are then evaluated using the finite volume method implemented in the open-source platform OpenFOAM®. In this work to verify the solver in porous media we simulated fluid flow around sphere in body-centered cubic (bcc) lattice and calculated the dimensionless permeability for a wide range of radius and porosity; the results are comparable with those obtained by using carman-kozeny equation. Then this solver is performed on realistic sample to investigate the effect of sample size on calculated permeability and tortuosity and the mesh refinement levels for a fixed image resolution.
    Keywords: CFD, Computed Micro-tomography, Digital Rock Physics, Finite Volume Method, OpenFOAM, Permeability
  • Mohammad Hossein Seraji, Hasan Khaleghi * Pages 101-110
    In the present paper, a three dimensional annular developing incompressible laminar flow through 270- degree curved pipe is numerically simulated. The dimensionless governing equations of continuity, momentums and energy are driven in toroidal coordinates. The governing equations are discretized by projection algorithm using forward difference in time and central difference in space. A three-dimensional computer code together with a grid generation program are developed in toroidal coordinates by which the present results were obtained.There is a non-uniform heat source q˝=Be^Aθ in the solid core and the outer wall is assumed to be adiabatic. Considering the effect of Reynolds number on thermo-hydraulic properties such as formation of secondary flow and axial velocity, it is possible to increase heat transfer using a non-uniform heat flux instead of the uniform one. The numerical results indicated that the average Nusselt number is increased by non- uniform heat flux compared with the uniform one assuming that both have the same average flux values. Also, the results indicate heat transfer increases as the aspect ratio is reduced.
    Keywords: Curved pipe, non-uniform heat source, Projection algorithm, Toroidal coordinates, Annular flow
  • Amir Heidari *, Parisa Shamlou Pages 111-121
    Wall-to-bed (or wall-to-fluid) heat transfer issues in trickle bed reactors (TBR) has an important impact on operation and efficiency in this category of reactors. In this study, the hydrodynamic and thermal behavior of trickle bed reactors was simulated by means of computational fluid dynamics (CFD) technique. The multiphase behavior of trickle bed reactor was studied by the implementation of the Eulerian-Eulerian multiphase approach. Also, bed porosity effect was modeled by porosity function method. In order to study the effect of operating parameters on wall-to-bed heat transfer, the influence of catalyst particle diameter and catalytic bed porosity was investigated on wall-to-bed Nu number. The results showed that the enhancement of catalytic bed porosity from 0.36 to 0.5 decreases the Nu number about 15% due to a reduction of liquid velocity adjacent to the reactor wall. Also, the increase of particle diameter from 4 to 6 millimeter decreases wall-to-bed Nu number about 15% owing to a reduction in liquid phase volume fraction.
    Keywords: CFD Simulation, Eulerian-Eulerian Approach, Wall Effect, Trickle Bed Reactors, Wall-to-Bed Heat Transfer
  • Samira Jamali, Alamooti, Rahmat Sotudeh, Gharebagh * Pages 123-135
    Vibration signals were measured in a lab-scale fluidized bed to investigate the changes in particle sizes. Experiments were carried out in the bed with a different mass fraction of coarser particles at different superficial gas velocities, and probe heights. The S-statistic test evaluates the dimensionless squared distance between two attractors reconstructed from time series of vibration signals. Values of parameters needed for the attractor reconstruction were derived from time series. These parameters consist of time delay, embedding dimension, bandwidth, and segment length with the values of 1, 35, (0.4-0.8), and (300-400), respectively. To reduce the sensitivity of the S-statistic to small changes in superficial gas velocities, the vibration signals were normalized in order to apply the attractor comparison test. The results showed that the attractor comparison can be a reliable technique for detecting particles size changes in fluidized beds even with small changes in the amount of coarser particles. The sensitivity of the method to particle size changes was decreased with an increase in superficial gas velocity. The results also show that the S-statistic test was almost independent of the measurement position of the vibration signals.
    Keywords: Agglomeration, Hydrodynamics, Fluidization, Particle Size Changes S-Statistic, Vibration Signature