جستجوی مقالات مرتبط با کلیدواژه "آنالیز حساسیت" در نشریات گروه "شیمی"

Today, the CO2 emission from the combustion of fossil fuels is recognized as one of the main causes of global warming and its consequent problems. Oxy-fuel combustion (OFC) is an effective way to separate CO2 from combustion flue gas. CO2 Compression and Purification Unit (CO2CPU) is a relatively new industrial unit for the separation of CO2 from the combustion gas produced by OFC process. However, the high energy required for the compression and refrigeration process is one of the main challenges of this unit. Therefore, identification and sensitivity analysis of the parameters affecting the process are needed for appropriate optimization and control of these parameters. The present study, while introducing this unit, aimed at sensitivity analysis, optimization and improvement of the process. The process was simulated in the Aspen Plus environment. In addition, Peng-Robinson thermodynamic equation of state was applied to estimate the thermodynamic properties and it was improved using the data ​​in the literatures to increase the accuracy of the thermodynamic coefficients. Given that the interaction of operational parameters is effective on the optimization results, the response surface methodology (RSM) was employed for optimization. The results of this study show that the process can be performed at 25 bar pressure by improving the operating conditions, while the operating pressure of this process was previously reported to be 30 bar. Obviously, reducing operating pressure decreases not only the operating costs but also the investment costs and thus, the total costs.

One way to progress towards sustainable energy is to use solar energy in the world. Iran also has great potential for the use of solar energy, but identifying suitable areas for the construction of solar power plants is an important issue. The purpose of this study is to evaluate the solar energy potential of 9 provincial centers in Iran with 3 multi-criteria decision-making methods Simple Additive Weighting, TOPSIS, and ELECTRE. In this regard, the three main criteria of installation location, weather conditions, and risk have been used, which include 11 sub-criteria and were weighed by the Shanon entropy method. In this weighting, the highest and lowest weights were allocated to population criteria and horizontal radiation, respectively. The results of prioritization also show that Zahedan has priority over other options in all three methods. Zahedan's score in the Simple Additive Weighting method is 0.488904, and in the TOPSIS method is 0.8485 and in the ELECTRE method, Zahedan and Tabriz both with 5 advantages over other Options are a priority, also Tehran was selected as the worst option for the construction of solar power plants, and the score of this option in the Simple Additive Weighting method is 0.167015, in the TOPSIS method 0.4452316 and the ELECTRE method, along with Kerman, without having superiority over other options, were in the last priority. Also, in 6 different cases, sensitivity analysis was performed on the presented models. The results of the sensitivity analysis show that the TOPSIS method is less sensitive to the weights of the indicators than the other two methods.

Carbonate acidizing modeling presents an effective tool to determine dynamic behavior trends during matrix acidizing treatment. A successful matrix acidizing process requires a minimum volume of injected acid while creating highly conductive wormholes. In this work, the two-scale continuum model was used to simulate carbonate acidizing using finite difference approach.  This model describes the reactive transport of acid at the Darcy scale and determines the local permeability, porosity, pore radius, and solid-fluid interfacial area changes at the pore-scale through structure-property relationships. In this study, a two-dimensional model was employed with constant flow rate inlet boundary condition, constant pressure outlet boundary condition, and no flow boundary condition on the lateral sides. To perform a grid independent verification, the normalized acid concentration was plotted versus mesh elements which, then, results in determining the optimum number of grid blocks. To solve governing equations, finite difference approach was used by employing initial and boundary conditions. The results of the two-dimensional homogeneous model revealed that there is a uniform acid concentration profile with a reduction trend during the model length. A sensitivity study on acid injection velocity in a heterogeneous model showed that there is an optimum injection velocity of 0.33 to 1.5 cm/s in which deep wormholes with a minimal amount of acid are created. Moreover, as time passes, the reactive dissolution process takes place and results in a dynamic change in the model porosity. This model indicated a good capability to qualitatively capture the experimentally observed wormhole propagation and growth.