Journal of Chemical and Petroleum Engineering
Volume:56 Issue: 2, Dec 2022

The flow responses of aramid and cellulose nanowhisker (fibrids) or CNCs (cellulose nanocrystal) suspended in a sulfuric acid and water respect at loadings of about 17% weight fraction was determined in transient shear flow. The effect of temperature and shearing conditions were examined. Aramid solution exhibits strong shear thinning with power law indices about 0.2-0.3, and cellulose nanowhisker suspension indices is below 0.15. Formation of an interacting flocculated network at rest is the reason for the large relative viscosity and offers the least flow resistance during shear flow. The structure formed at rest is easily destroyed, and this is the reason for the observed shear thinning. Evolution of shear stress data versus time over four of shear rate were described the structure of nematic phase in aramid\sulfuric acid solution. Also shear rheology results of nanowhisker/water suspension show shear thinning behavior, and behave as a plastic system at different temperature. For spinning process, the aramid\sulfuric acid dope through the air gap entered into cold water. Orientation of polymer solution emerged from the spinneret and through very high extensional shear in the air gap resulted in excellent tensile properties of the final spun fibers.

In this study, the effect of silica nanoparticles on the stability of foams that are stabilized with sodium dodecyl sulfate anionic surfactant was investigated. This surfactant can significantly increase the stability of the foam by reducing the surface tension. For experiments, first, the stability of the foam obtained from this surfactant in the presence of deionized water and then in the presence of NaCl solution and seawater were investigated. Then, by changing the salinity of NaCl solution and seawater, a change in the stability of the resulting foams was investigated, and the results were reported. The effect of the simultaneous presence of different concentrations of silica nanoparticles in the above solutions was investigated, and stability results were reported. According to the experimental results, the amount of foaming and the half-life of foam in the presence of deionized water is equal to 201 minutes, but the addition of brine reduces this amount. The presence of nanoparticles increases stability. In the presence of deionized water and surfactant, it reaches more than 280 minutes. Finally, the surface tension changes in the optimal concentration of the surfactant in exchange for the change in the concentration of nanoparticles were investigated. In the optimal concentration of surfactant and NaCl solution, the surface tension decreased to 21 mN/m.

In this study, the effective parameters in mass transfer in the process of gas absorption in the bubble column by amine solvents have been investigated. Also, the aim of this study is to present a general and accurate correlation with the least simplifying assumptions to calculate the mass transfer flux of gas phase to liquid phase components in three electrolyte systems MDEA-Pz, MEA-Pz, and MEA-MDEA. The effect of parameters on mass transfer such as retention time, apparent gas velocity, liquid phase properties, operating conditions, type of distributor, and bubble characteristics was analyzed. Effective parameters were expressed to achieve functional correlations using dimensionless numbers by using the pi-Buckingham theorem. The correlation coefficients for MDEA-Pz, MEA-Pz, and MDEA-MEA were obtained at 0.951, 0.981, and 0.924, respectively. The mean relative error obtained from predicting the mass transfer flux correlation for all three MDEA-Pz, MEA-Pz, and MDEA-MEA amine combination systems was 3.6, 4.5, and 4.8%, respectively. The results showed that the proposed correlations for mass transfer flux compared to other correlations have high accuracy.

Based on the Tao-Mason equation of state we have proposed a nonlinear ordinary differential equation that asymptotically converges to the compressibility factor of a pure substance or a mixture of chemical species. We have used the Dormand-Prince pair algorithm to solve the aforementioned differential equation in a purely numerical manner. Our method is devoid of the adverse convergence issues that are usually associated with the Newton-type solvers. We have provided two case studies concerning two industrially common compounds namely ethane and carbon dioxide, for the sake of exposition. For 96 points of different temperatures and pressures, our method succeeded at calculating the compressibility factor of carbon dioxide with an average absolute error of 6.53×10-5 and a maximum absolute error of 4.79×10-4. Unlike the previous root finding algorithms, we only need to perform “formal” polynomial deflations in our method, which circumvents the computation-intensive synthetic divisions, to obtain all compressibility factors offered by the Tao-Mason EOS.

This study aims to numerically determine the roles of the geochemical reactions during the injection of a strong acid into a sandstone sample. As a case study, we used laboratory results of hydrochloric acid (HCl) injection into a sandstone core plug sample from the literature. As the exact cement composition of the implemented sandstone was not available, two probable cement compositions were considered (i.e., calcite and dolomite cement). A fully-implicit model, coded in Python, was used to simulate the underlying geochemical reactions during the HCl injection (i.e., equilibrium and kinetical reactions). In addition, the reactive surface area and porosity-permeability changes of the rock sample were included in the model. The modelling results show that dolomite cement matched better than calcite cement with the experimental acidizing data. A perfect effluent pH prediction was therefore achieved when the reactive surface area was considered as a function of mineral volume fraction. Moreover, a detailed analysis of the dissolution/precipitation rate of different minerals involved in simulations was provided. The presented model improves our understanding of sandstone acidizing by determining dominant reactions.

Microchannel reactors, known as high-process intensification reactors, are utilized in various fields due to their intensive micromixing performance, which is crucial for fast chemical reactions. The work presented here depicts the Computational Fluid Dynamics (CFD) modeling of five generic microchannel reactors (MCRs), namely T-square, T-trapezoidal, Y-rectangular, concentric, and caterpillar designs based on the experimental published data of the parallel competing Villermaux-Dushman reaction. The main objective of this study is to numerically quantify the effects of the total liquid flow rate (1-18 mL/min), micromixer dimension (150-1600 µm) and configuration on the values of the pressure drop, energy dissipation, mixing time, and segregation index (XS).The CFD results revealed that under constant concentrations of the reactants ( , , , = 0.091, 0.0224, 0.016, 0.0033 M), the dissipation rate intensified with increasing the total flow rate but weakened with the change in symmetry and the channel diameter. Further, the estimated values of the segregation index illustrated that the caterpillar design could bring about a reasonable enhancement in micromixing performance with energy dissipation (ε) and segregation index of 1335700 W/kg and 0.0024, followed by T-square and Y-rectangular with Xs~ 0.0061 and 0.0161, respectively. The low values of mixing time for caterpillar MCR were found in the range of 0.01-0.1 s for liquid flow rates of 1-18 mL/min.

COVID-19 has hurt the world economy since its global spread. So various economic sectors, particularly the energy sector, have been impacted negatively. Statistical analysis has been used in numerous research to assess the effects and repercussions of COVID-19 on the energy sector. However, the influence of its interaction with other sectors, such as households and businesses, on the energy sector has not been studied. The DSGE model provides a framework for analyzing the effect of COVID-19 on the energy sector in dealing with households, businesses, government, and central bank policymakers. The energy sector is separated into two parts in this paper: renewable energy and fossil fuel energy. The impact of COVID-19 on consumption, production, investment in renewable energy, and investment in fossil fuels was then studied using the DSGE framework. The results indicated a decline in production and investment in these two sectors, as well as a rise in consumption. The results also indicate that the fossil fuel energy sector has had a greater decline in production, a greater increase in production costs, a greater loss in investment, and a greater increase in consumption than the renewable energy sector.

A numerical evaluation was performed to understand the effect of catalytic bed geometry on the catalyst deactivation and propane dehydrogenation reactor performance with respect to coke formation. Furthermore, the temperature distribution and propane conversion along the reactor were studied. The governing equations with appropriate initial and boundary conditions were solved numerically, while two different bed arrangements (i.e. rectangular and parallelogram) were evaluated to find the optimized geometry in order to avoid the creation of hot spots. Findings indicated that parallelogram arrangement causes more conversion percentage owing to more axial as well as the radial mixing of reactants compared to the rectangular arrangement. Moreover, the obtained numerical results revealed that the optimum operating temperature to achieve the maximum conversion is 550 °C. As the temperature increases from 450 ºC to 650 ºC, the conversion of propane increases from 68.15% to 99.51%, during the reactor length. When the temperature exceeds above the optimum operating temperature, hot spots are created due to coke formation and also accumulation of coke on the catalyst bed surface that will lead to the deactivation of catalysts. The results of this work can be useful to examine the effects of operating conditions to better understand physical and chemical phenomena occurring in the propane dehydrogenation reactor.

This work aims to develop a one-dimensional mathematical model for a novel multi - tubular thermally coupled reactor in the steady-state condition. The mentioned thermally coupled reactor includes the endothermic reaction of cyclohexane dehydrogenation in the inner tube and the exothermic hydrogenation reaction of nitrobenzene to aniline in the outer one. This research aims to use the generated heat by the exothermic process instead of the heat supplier equipment such as heaters and furnaces. Therefore, the proposed configuration acquires a remarkable reduction in energy consumption. Besides, the required hydrogen is provided for the hydrogenation reaction of nitrobenzene to aniline by the dehydrogenation reaction of cyclohexane in the same reactor. Furthermore, higher efficiency is achieved in the proposed configuration based on the heat transfer between the exothermic and endothermic sides of the thermally coupled reactor rather than the conventional reactors that operate under the same conditions as the thermally coupled reactor.

The diffusion coefficient of gases in a wide range of chemical processes is of great importance. Semi-empirical models for diffusion coefficient prediction are useful due to their relatively lower cost compared to laboratory methods. In this study, to facilitate the equations and accelerate the calculations, appropriate models have been presented using existing parameters such as molecular mass and critical properties to determine the binary diffusion coefficient of gases. The calculations have been performed using a particle swarm optimization (PSO) algorithm. This model has been used to obtain the diffusion coefficient of 84 gas dual systems at P=101.325 kPa and variable temperature (373.15-673.15 K). Also, during the validation phase, the suggested model attained the most accurate prediction with R^2=0.9989. This model is capable to predict the diffusion coefficient of gases with a mean relative error percentage of 2.57% and mean square error percentage of 0.15% compared to actual data. These results are significantly better than those obtained from other models.

After the carbonate reservoir acidizing and the damaged wellbore stimulating, the pH of the environment has particular importance in reducing corrosion during production. In this study, the pH change after the calcium carbonate and hydrochloric acid reaction was modeled, and the optimum pH after the reaction was determined. Also, the effect of temperature HCl concentration and calcium carbonate grain size on final pH was investigated. According to the findings, an increase in temperature causes an increase in final pH. The effect of concentration is against temperature, and pH decreases with increasing concentration. Also, the grain size of calcium carbonate particles has an insignificant effect on pH alteration. Hence, the maximum pH in all grain sizes occurs at 70 oC and 1.95 wt.% HCl and equals 6.7. The R square, adjusted R square, and predicted R square of the models are acceptable values and show that experimental data agrees with prediction data.

In this research, the influence and comparison of ultrasonic and microwaves on the wettability of carbonate rock have been investigated. Wettability is one of the most fundamental parameters of the oil reservoir, according to which the fluid movement in the porous medium can be examined. The aged thin sections were placed in a microwave oven and an ultrasonic bath and they were exposed to radiation for 2-10 minutes. Using the contact angle analysis, it was observed that the angle between the rock and oil drop of microwaved and ultrasonicated samples changed by 57 and 71 degrees, respectively. Contact angle and temperature changes started faster for the ultrasonicated samples. The surface charge of the rocks was determined by zeta potential analysis, and it was found that in both samples, in the first minutes of radiation, negatively charged colloids were liberated from the samples by absorbing the waves, which reduced the surface negative charges, and with the continued radiation, positively charged colloids were decreased due to the evaporation of light oil compounds. The reduction of zeta potential occurred faster for the ultrasonicated sample, but the rate of decrease was lower. By examining Fourier-transform infrared spectroscopy (FTIR) results, it was concluded that the heavy compounds on the surface of the samples were cracked and turned into lighter hydrocarbons, and the changes for both samples were almost equal. Also, the polar compounds, sulfur, and nitrogen in samples increased, decreased, and decreased respectively for both samples, and these changes were more for the ultrasonicated samples.