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Theoretical Foundations of Chemical Engineering - In this work, with the aim of accurate prediction of water content, H2S and CO2 absorption capacity of diethanolamine (DEA) solvent in Khangiran...  相似文献   
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The thermal property of single layer graphene sheet is investigated in this work by using an embedded approach of molecular dynamics (MD) and soft computing method. The effect of temperature and Stone–Thrower–Wales (STW) defects on the thermal conductivity of graphene sheet is first analyzed using MD simulation. The data obtained using the MD simulation is then fed into the paradigm of soft computing approach, multi-gene genetic programming (MGGP), which was specifically designed to model the response of thermal conductivity of graphene sheet with changes in system temperature and STW defect concentration. We find that our proposed MGGP model is able to model the thermal conductivity of graphene sheet very well which can be used to complement the analytical solution developed by MD simulation. Additionally, we also conducted sensitivity and parametric analysis to find out specific influence and variation of each of the input system parameters on the thermal conductivity of graphene sheet. It was found that the STW defects has the most dominating influence on the thermal conductivity of graphene sheet.  相似文献   
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Precise estimation of temperature variations throughout gas production systems can enhance designing the production amenities. Routine methods for determining the temperature profiles in gas production systems are based on the gas composition and flash calculations. However, if the gas compositions are not available, the gas production system can be modelled by employing a black-oil approach, which is also a method for calculating the oil/gas resources and for modelling the gas reservoir operation. Accordingly, for black-oil models and when the natural gas compositions are not accessible, applying robust predictive tools in this research is of high interest in natural production systems. The current study places emphasis on applying the predictive model based on the least- squares support vector machine (LSSVM) to estimate precisely the proper temperature drop associated with a given pressure drop throughout the natural gas production systems based on the black-oil approach to acquire an accurate result for the temperature drop of natural gas streams. Genetic algorithm was used to optimise hyper-parameters (γ and σ2) which are embedded in the LSSVM model. Using this method is simple and it accurately determines the temperature drop through the natural gas stream with minimum uncertainty.  相似文献   
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Ethylene oxide production process is one of the highest energy consumers in chemical industry, and therefore even a slight improvement in its overall efficiency can have a significant impact on the sustainability of the process. Efficiency improvement can be carried out using the exergy-aided pinch analysis outlined in this paper. The overall exergy loss distribution in different unit operations of an ethylene oxide process was first evaluated and mapped out in the form of “visualized exergetic process flowsheet”. An initial analysis of the four main functional blocks of the process showed that the exothermic reaction block contained the largest exergy loss (6043 and 428 kJ/kg of internal and external losses, respectively) which can be reduced by isothermal mixing, as well as increasing reaction temperature and reduction in pressure drop. The absorption block was also estimated to have the second highest contribution with total exergy losses of 3640 kJ/kg which were mainly due to the cooling column. These losses were then recommended to be reduced by improvements in the concentration and temperature gradients along the tower. Following the block-wise analysis, exergy analysis was then carried out for individual unit operations in each block to pinpoint the main sources of thermal exergetic inefficiency. Thermal solutions to reduce losses were also proposed in accordance with the identified sources of inefficiency, leading to a comprehensive list of cold and hot process streams that could be introduced to reduce losses. Finally, pinch analysis was brought into action to estimate the minimum energy requirements, to select utilities, and to design heat exchanger network. Thus, the methodology used in this work took advantage of both exergy and pinch analyses. The combined thermal-exergy-based pinch approach helped to set energy targets so that all the thermal possible solutions supported by exergy analysis were considered, preventing exclusion of any hot or cold process stream with high potential for heat integration during pinch analysis. Results indicated that the minimum cold utility requirement could be reduced from 601.64 MW (obtained via conventional pinch analysis) to 577.82 MW through screening of streams by the combined methodology.  相似文献   
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The gas holdup is an important parameter that is needed for design and development of surface facilities and transportation pipelines in the field of petroleum engineering. There is no general model for prediction of this parameter in different systems and under different conditions. As a result, development of accurate and general models for prediction of this parameter in various situations is of great importance. This study presents new experimental gas holdup data in the kerosene+CO2 and kerosene+N2 systems. The experimental data were measured by using a bubble column setup. Moreover, a computer-based model namely PSO-ANFIS model is also developed for prediction of the gas holdup in different systems. A total of 818 experimental gas holdup data in various systems were utilized including the newly measured experimental data in the present work as well as experimental data from several published works in the literature. Results showed that the developed PSO-ANFIS model is accurate for prediction of experimental data with an R2 value of 0.998 and average absolute relative deviation (AARD%) of 3.4%.  相似文献   
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Adsorption of heterocyclic sulfur- and nitrogen-containing compounds by mesostructure adsorbent (MSU-S) and its modified form with cobalt oxide is studied using model fuel. The results of characteristic tests (XRD, N2 adsorption–desorption, FTIR, and SEM) indicate that CoO impregnation causes a negative impact on mesoporous structure, crystalline phase, and particle shape along with a positive effect on surface ion exchange. CoO modification increased the adsorption loadings of DBT and BT to about 33.6% and 45.7%, respectively. For nitrogen compounds adsorption with the model fuel, adsorption loadings of quinoline and carbazole increase by 6.7% and 8.6%, respectively. Data fitting for carbazole, DBT, and BT is achieved better by the Langmuir model than the Freundlich model, and the data of quinoline fitted very well to the Freundlich model for CoO-MSU-S.  相似文献   
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An accurate prediction of the mutual solubilities of hydrocarbons and water is extremely useful in oil, gas, and chemical industries. Estimating the solubility of hydrocarbons in water is required to describe their phase distribution through the removal process and also in the design of separation equipment. The current study plays emphasis on applying the predictive model based on the least square support vector machine (LSSVM) to estimate mutual water-hydrocarbon solubility at a wide range of conditions. A genetic algorithm (GA) was employed to choose and optimize hyperparameters (γ and σ2), which are embedded in LSSVM model. Utilization of this model showed high competence of the applied model in terms of coefficient of determination (R2) of 0.9998 and 0.9994, Average absolute relative deviation (AARD) of 1.1378 and 1.12459 from experimental values for predicted water solubility in hydrocarbons and hydrocarbon solubility in water, correspondingly. Using this method is quite simple and accurate to determine the mutual water-hydrocarbon solubility with negligible uncertainty.  相似文献   
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One of the advantages of managed pressure drilling (MPD) is an increase in drilling speed and a reduction of mud filtrate invasion as a result of decreasing pressure differential. Reduction of overbalanced pressure (OBP) leads to a decrease of confining pressure around the formation rock and consequently the rock is broken more easily under the bit action and therefore the rate of penetration (ROP) increases. It is also obvious that decreasing the overbalanced pressure results a reduction in mud filtrate invasion and formation damage. In the present article the effect of MPD on increasing rate of penetration and decreasing mud filtrate invasion is studied. Artificial neural networks (ANN) were implemented to develop a model for estimation of ROP by using operational inputs including overbalanced pressure. Using the ANN model, the effect of OBP was analyzed. The effect of OBP on mud filtrate invasion was studied by using developed models of the process and simple Darcy’s law. The results demonstrated that MPD leads to about 30% increase in rate of penetration and 50% decrease in mud filtrate invasion.  相似文献   
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