Sharif Digital Repository

Continued uncontrolled gas emission can cause extreme changes in climate all over the world and threaten the life So, the removal and/or reduction of CO2 from the atmosphere is essential to prevent its side effects. CO2 separation is the costliest part of the gas removal process from fossil fuel combustion. Among several available CO2 capture technologies, the MEA-based post-combustion CO2 capture process is considered a mature technology for mitigating CO2 emissions. In this study a steady-state MEA-based CO2 capture process from the coal power plant is developed in Aspen Plus. Subsequently, steady-state model with appropriate modifications, is exported into Aspen Plus Dynamics to study... 

Two experimental models were designed and tested to extract energy from vortex induced vibrations of a elastically mounted one degree of freedom rigid cylinder in the Reynolds range of 120000 < Re <220000. In the first model the amplitude and frequency of the movement was measured then a second model was designed to be tested in the Emam Hossein marine laboratory. The model was designed in a way that many of its properties like mass ratio, spring constant and damping coefficient were able to be altered. In this study the vortex induced vibration of an elastically mounted cylinder was scrutinized in high Reynolds and very low mass ratios for the first time and an amplitude ratio of 2.49 were... 

The aim of this study is to survey the ability of vortex tube cascade for separating heavy components of a gas mixture. For this purpose, three vortex tubes based on previous experiences have been manufactured. Also, a helical double pipe heat exchanger has been designed and constructed. Because of the vortex tube’s ability in developing thermal separation, the effect of thermophysical parameters like feed’s temperature, inlet and outlet pressure of air on the thermal separation performance were evaluated. The recommended correlations for estimating outlet temperature of hot and cold flows, have been validated against experimental data. Moreover, various arrangements of vortex tubes to... 

Supersonic separators (3Ss) are used in gas separation processes such as dehumidification of humid air thanks to their high performance and good pressure recovery. Moreover, 3Ss because of their simple mechanical construction and absence of any environmental impact are preferred to other dehydration methods of natural gas, such as adsorption, cooling, and membrane. Also using the 3Ss for relatively large facilities with considerable investment is more than evident. In the first phase of present study, 2-D simulation is performed to investigate the effect of operational and thermo-physical parameters on shockwave position in a specially conceived wet air 3S. Moreover, the effect of cyclonic... 

One of the most important environmental problem across the world is global warming due to increase in greenhouse gas concentration in atmosphere. The main objective of this thesis is to try to find some ways that lead to stop or decrease, increasing trend in greenhouse gas emission, espicialy CO2. The investigation of the sources of emission of CO2 and proposed methods to decrease the rate of the emission, reveals that sepration of CO¬2 from combustion products and its storage is the only promising solution of this problem. The common feature of all propsed methods for elimination of CO¬¬2 from combustion gas, is the presence of a separation step. The addition of this separation step to... 

Supported Ionic Liquid Membranes (SILMs) are fabricated by saturating the pores of a porous support with ionic liquids. To assess the performance of SILMS, it is necessary to obtain data about the properties of ionic liquids such as diffusivity, solubility, and etc. To accomplish this task, in this project the permeability and diffusivity of CO2 and CH4 through three immidazolium-based ionic liquids: [bmim][PF6], [hmim][Tf2N], and "1-methyl-3-(3- tri methoxi silil propyl) imidazolium bis (tri fluoro methyl solphonyl)" , in the temperature range between 27-45 ℃ and pressures within 10-50 kPa, are measured. It is shown in data validation section that the results of this study are in good... 

Due to the increasing concentration of greenhouse gases in the earth's atmosphere and their destructive consequences, many scientists and researchers have turned to preventing the emission of greenhouse gases, such as carbon dioxide. One of the primary sources of carbon dioxide emissions is flue gases. Carbon dioxide is one of the most important greenhouse gases, the release of which causes global temperature increase and climate change. One of the options for reducing carbon dioxide emissions from gas streams is using reactive amine solvents, considered the most critical technologies for carbon dioxide removal. The only commercially available carbon dioxide separation method is absorption... 

Separation of speech signals has many applications. For example, it is used human-machine communications. This problem can be divided into three categories: overdetermined, determined and underdetermined. If the number of mixtures is greater than the number of sources, the problem is called overdetermined; if it is equal to the number of sources, the problem is called determined and if it is less than the number of sources that problem is called underdetermined. This MS thesis studies the undertermined case. Moreover, speech signals are sparse in time-frequency domain, meaning that in each time-frequency point, usually only one source is active. So, for separatig the speech signals,the... 

Particle separation has a variety of applications in biology, chemistry and industry. Among them, circulating tumor cells (CTCs) separation has drawn significant attention to itself due to its high impact on both cancer diagnosis and therapeutics. In recent years, there has been growing interest in using inertial microfluidics to separate micro/nano particles based on their sizes. This technique offers label-free, high throughput, and efficient separation and can be easily fabricated. However, further improvements are needed for potential clinical applications. In this study, a novel inertial separation technique using spiral microchannel with stair-like cross section is introduced. The... 

This study is aimed to investigate the effect of Fe3O4 nanoparticles in liquid membrane efficiency, four liquid membrane was studied. Due to the unique properties of ionic liquids have been highly regarded. Hence in this project for both ionic liquid and conventional liquid permeability and selectivity has been investigated.
One of the most important features of the liquid membrane is the stability. Performance of cyclohexane liquid indicated that it is not useful for liquid membrane. To improve the stability of the membrane of cyclohexane ionic liquid membrane is used as shielding.
Permeability of O2 and CO2 in five partial pressure in the feed gas (20, 35, 50, 65 and 80%) liquid... 

In the nuclear industry, gas centrifuges are considered of high importance for the purpose of uranium enrichment. Today, with advances in science and technology, the use of gas centrifuges for separating isotopes other than uranium, is so common. With respect to the use of conventional methods such as Pancake equation in calculating the velocity profile in centrifuges, it is needed that A^2=(MV^2)/2RT≫1 (M: Feed molecular weight; V: Peripheral speed of centrifuge; T: Mean temperature of feed; R: The universal constant of gases). While the molecular weight of the feed mixture gets lower, the A2 parameter gets closer to one. So, other methods for modeling the behavior of the gas in the... 

Waste of iron ore concentrate production plant of Chadormalu contains apatite mineral. The content of rare earths elements (REEs) in apatite concentrate of Chadormalu is about one percent. However, considering apatite deposite and production rate, extraction of REEs from apatite is one of valuable source for production of REEs. Lanthanum, cerium and neodymium which have most application amonge other REEs and have the highest frequency in the apatite. Due to their similar physical and chemical properties, it is difficult to separate individual rare earths from each other and the separation process are too complicated. In this study, in order to extract REEs from apatite, it was leached by... 

Membrane processes are accounted as the newest technology for gas separation and nowadays are more applicable in different petroleum, gas and petrochemical industries because of abundant advantages. One of important application of membrane gas separation technology is syngas adjustment and hydrogen enrichment. In this research, the appropriate alumina nanocomposite membranes for this purpose are prepared and their gas separation performance is investigated. Therefore the mixed matrix membranes, containing the continues polymeric phase polyethersulfone and dispersed phase alumina nanoparticles is synthesized by using methods of experimental design. As the best of our knowledge, there is no... 

With the increasing number of applications in internal combustion engines, environmental impact and air pollution caused by emissions has been much attention. Natural gas is a promising fuel for limiting pollution laws in many countries. The use of fuel with a higher ratio of hydrogen gas to carbon pollution reduction motor. In this context and with regard to development policy and also due to the diversity basket NGV fuel, fuel injection, has been modeled analytically and numerically in a direct injection engine. In this study, an analytical model for spray injection fuel delivery and is dissolved. The resolution of the method of separation of variables is taken. The effect of the nozzle... 

A new microfluidic device is introduced for sorting the particles based on the hydrodynamic resistance induced in a microchannel which is not needed for additional detection or sorting modules. Hydrodynamic resistance affects physical properties, such as size and deformability of the particle. This device could apply application in cell sorting for remedies, diagnostics, and industrial applications. The device design is performed using an equivalent resistance model, and also numerical simulations are performed. For validation of the results, they are compared with experimental results. Moreover, we will discuss threshold particle size and will introduce a way to approximate it to ... 

Triclosan is widely used as an antibacterial agent in personal health care products, especially in recent years with the spread of the Coronavirus. This substance is one of the emerging contaminants, and due to its stable and toxic nature, this material cannot be destroyed in the process of biological wastewater treatment. In this research, a new bacterial strain was isolated and purified from industrial wastewater for the biological removal of triclosan. Based on 16S rRNA sequencing, it was found that the isolated strain belongs to the Enterobacter cloacae family and can grow in high concentrations of triclosan. It was observed that naphthalene dioxygenase and laccase enzymes are active... 

Porous materials using polymers have been developed for a variety of industrial applications. These structures mostly contain well-aligned microchannels and exhibit good mechanical properties and high porosity.There are several ways to prepare porous polymeric structures, such as sintering, stretching, track etching and phase separation processes. In this work Phase separation method using anti-solvent of selected polymer in liquid nitrogen was used to fabricate the porous structures. Considering physical and chemical peroperties of polycyclic aromatic hydrocarbons, porous polystyrene make to be good sorbents. Solvent supported microextraction technique was applied to extract polycyclic... 

In today's complex engineering systems, any increase in efficiency naturally comes with concerns about accepted level of safety. As demand for aerial transportation is increasing, more researches are conducted to increase the capacity of current controlled airspaces; as the limited capacity of the so called "en-route" corridors appears to be the main concern in the industry. Meanwhile, a solution is expected to be in more efficient exploitation of the current airspace capacities via optimizing the standards related to maintaining Separation Minima (SM) among flying aircrafts. Current standards assume an aircraft to be at the center of a circle with a radius equal to 5 nm. In this work,... 

It is necessary to monitor pollutants in aquatic samples, because many of these compounds can pose threats to human health and the ecosystem. Separation technology based on magnetic materials has received considerable attention in recent years. The magnetic extraction method is not only convenient, economical and highly efficient, but it also overcomes problems with conventional solid-phase extraction. In order to remove anionic dyes from single and ternary systems, zinc ferrite nanoparticle was synthesized using co-precipitation method and its surface was modified by Cetyltrimethyl ammonium bromide (CTAB) cationic surfactant. Surface characteristics of ZFN-CTAB was studied using Fourier... 

Because of higher hydrogen demand in recent years, study of hydrogen separation from gas mixtures is highly regarded. Because of some parameters such as high surface to volume ratio and ability to withstanding high pressure, polymeric hollow fiber membranes have a good potential of hydrogen recovery. So in this study, fabrication of single-layer and dual-layer hollow fiber membranes have been investigated. Selective polymer that used in both single and dual layer membranes is polyethersulfone. Membranes were fabricated by dry-wet phase inversion method and effects of extrusion rates and their ratio, composition and temperature of polymer solution, composition of bore fluid, coating and air...