Modeling and Simulation
A. Das; N. Azimi
Abstract
This research presents the performance of bladeless wind turbines. It also familiarizes readers with the phenomenon of eddy current, which serves as the foundation for bladeless turbines. In this direction, these kinds of bladeless turbines have been designed, modeled, and simulated. Firstly, a two-dimensional ...
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This research presents the performance of bladeless wind turbines. It also familiarizes readers with the phenomenon of eddy current, which serves as the foundation for bladeless turbines. In this direction, these kinds of bladeless turbines have been designed, modeled, and simulated. Firstly, a two-dimensional vibrational movement of the cylinder with a natural frequency of 2 Hz was modeled at Re = 51000. Additionally, it was noted that the values of the displacement amplitude, and lift coefficient are -0.1-0.1, and -1.5-1.5 respectively. After that, using 2D simulation, the impacts of two different geometries, horizontal and vertical ellipsoids, on displacement amplitude are examined. Investigations were conducted on important factors such as lift coefficients and displacement amplitude, as well as the vortex flow pattern formed behind these shapes. It was discovered that the vertical ellipsoid shape had the maximum values for the height of the displacement amplitude, and lift coefficient. The most important factor influencing the performance of this type of geometry was examined, namely the dimensionless Reynolds number, which ranges from 15000 to 90000. It was determined that the intended geometry exhibited a larger displacement response as the Reynolds number increased.
Modeling and Simulation
K.H. Hanon; E. Ebrahimi
Abstract
The purpose of this research is CFD modeling of the fluid flow inside an industrial valve in order to discover the areas with high shear stress and to determine the effect of hydrodynamic on the erosion rate. CFD results are compared with the existing experimental data in a valid reference and the model ...
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The purpose of this research is CFD modeling of the fluid flow inside an industrial valve in order to discover the areas with high shear stress and to determine the effect of hydrodynamic on the erosion rate. CFD results are compared with the existing experimental data in a valid reference and the model is verified with high accuracy. The impact of the pressure at inlet and the disc angle on the erosion is investigated. By increasing inlet pressure, maximum velocity, turbulence intensity, wall shear stress and particle erosion increased. However, the wall shear stress, turbulence intensity, and particle erosion are clearly reduced as the disc angle decreases. When the disc angle is less than 50o, the range of dependent parameters changes has a small value. Reducing the disc angle or increasing the inlet pressure led to an increase in cavitation. Therefore, to prevent the erosion of the butterfly valve, it is necessary to increase the disc angle or reduce the pressure at inlet. Erosion of the butterfly valve significantly occurred at the front and rear of the disc. Depending on the disc angle, the shear stress of wall for the modified configuration is 10 to 80 times lower than the original butterfly valve. Therefore, it can be stated that the modified geometry can reduce the wall shear stress and consequently the erosive for all the disc angles of the studied butterfly valve.
Modeling and Simulation
M. Khajeh Amiri; A. Ghaemi; H. Arjomandi
Volume 16, Issue 1 , March 2019, , Pages 54-64
Abstract
In this work, zeolite 13X with porosity structure has been used as an adsorbent for adsorption of CO2 flue gas. The effect of operating conditions including pressure and time on adsorption capacity were investigated. The experiments conditions are constant temperature, the range of pressure 1 - 9 bar ...
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In this work, zeolite 13X with porosity structure has been used as an adsorbent for adsorption of CO2 flue gas. The effect of operating conditions including pressure and time on adsorption capacity were investigated. The experiments conditions are constant temperature, the range of pressure 1 - 9 bar and the registration of adsorption capacity with passing of time. Experimental data were adjusted with adsorption isotherm models including two and three parameters isotherm. Also the process was studied in terms of kinetic models and after the implementation of the experimental data with kinetic models, the speed of this process equations were obtained. The best kinetic model for this process was selected first order equation. The results showed that adsorption capacity of 13X is 71.5 mg/g at pressure of 8 bars. Also the result indicate that 13x has high capacity at low pressures. With regard to achieved results for adsorption isotherm modeling, the adsorption isotherm followed of the three-parameter and among three-parameter models, Toth isotherm can be interpreted the process. Also the results of the fixed bed indicate a very high adsorbent selectivity to carbon dioxide adsorption and there was little oxygen and nitrogen adsorption.
Modeling and Simulation
k. movagharnejad; F. Saffar
Volume 15, Issue 2 , May 2018, , Pages 78-90
Abstract
In the present research, three different architectures were investigated to predict the coefficients of the Daubert and Danner equation for calculation of saturated liquid density. The first architecture with 4 network input parameters including critical temperature, critical pressure, critical volume ...
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In the present research, three different architectures were investigated to predict the coefficients of the Daubert and Danner equation for calculation of saturated liquid density. The first architecture with 4 network input parameters including critical temperature, critical pressure, critical volume and molecular weight, the second architecture with 6 network input parameters including the ones in the first architecture with acentric factor and compressibility factor. The third architecture contains 12 network input parameters including 6 input parameters of the second architecture and 6 structural functional groups of different hydrocarbons. The three different architectures were trained and tested with the 160 sets of Daubert and Danner coefficients gathered from the literature. The trained neural networks were also applied to 15 un-known hydrocarbons and the outputs (Daubert and Danner coefficients) were used to predict the saturated liquid densities. The calculated liquid densities were compared with the experimental values. The Results indicated that the coefficients obtained from the second architecture produced more precise values for the liquid densities of the 15 selected hydrocarbons.
Petroleum and Reservoir Engineering
F. S. Shariatmadar; Sh. Ghanbari Pakdehi; M. A. Zarei
Volume 13, Issue 1 , January 2016, , Pages 84-97
Abstract
Examination of the available ignition delay time data and correlations in the case of methane, butane, heptane, decane, kerosene, Jet-A and ethylene fuels, allowed the derivation and recommendation of standard equations for this property. In this study, a new accurate substance dependent equation for ...
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Examination of the available ignition delay time data and correlations in the case of methane, butane, heptane, decane, kerosene, Jet-A and ethylene fuels, allowed the derivation and recommendation of standard equations for this property. In this study, a new accurate substance dependent equation for ignition delay time as a function of pressure, number of carbon atoms, mixture equivalence ratio, fuel mole fraction and temperature has been developed to estimate ignition delay time of some hydrocarbon fuels. With the presented model, ignition delay time has been calculated and compared with the data reported in literature. The accuracy of the obtained model has been compared to the mostly used predictive models and the comparison indicated that the proposed correlation provides more accurate results than other models used in the previous works.
Modeling and Simulation
R. Rahimi; M. H. Soodmand; M. Zivdar; A. Alborzi; M. Rahmanian
Volume 12, Issue 1 , January 2015, , Pages 60-67
Abstract
The distillation process remains as the most common method ofseparation in chemical process industries. The energy used from this process accounts for an estimated 3% of the world energy consumption. The Dividing-Wall Column (DWC) for separation of multi-component mixtures has recently become a major ...
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The distillation process remains as the most common method ofseparation in chemical process industries. The energy used from this process accounts for an estimated 3% of the world energy consumption. The Dividing-Wall Column (DWC) for separation of multi-component mixtures has recently become a major concern ofindustries. The design ofDWC is based on Thermally Coupled Distillation System (TCDS) eliminating some of the operational equipment. This paper presents the results of simulation of a DWC by using 3-simple sequence column model based on shortcut method by a commercial chemical Engineering software for purification of1,3 butadiene unit. From the results, it is shown, by using a DWC instead of two conventional sequential column, the heat duties ofboth the condenser and the reboiler are reduced about 28.5% and also desirable purity ofthe key-components for the case ofstudy have been achieved.
Modeling and Simulation
Volume 2, Issue 1 , January 2005, , Pages 52-60
Abstract
n this paper, a mathematical model has been derived to predict the granulation time of anaerobic sludge in UASB reactors. In the proposed model, some physical, chemical and biological parameters affecting the granulation phenomena have been considered. To validate the model, 12 pilot-scale experiments ...
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n this paper, a mathematical model has been derived to predict the granulation time of anaerobic sludge in UASB reactors. In the proposed model, some physical, chemical and biological parameters affecting the granulation phenomena have been considered. To validate the model, 12 pilot-scale experiments in 4 UASB reactors are carried out and the results are discussed here. The reactors are started up at different environmental conditions and the granulation time in each experiment is determined. The results show that the model is able to explain different mechanisms involved in the granulation process.