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gas-absorption
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CO2 measurement of synthetic biogas by passing it through dilute NaOH solution
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 39, Issue 3 , 2020 , Pages 107-116 ; Shayegan, J ; Sharif University of Technology
Iranian Institute of Research and Development in Chemical Industries
2020
Abstract
The feasibility of measuring CO2 content in biogas was evaluated in this research. Firstly, Curtipot pH simulator was used to visualize the titration behaviors of various percentages of dissolved CO2 in a wide range of concentration of NaOH solution. As a general output of those simulations, it was shown that when the titration curves of different CO2 content samples are separated enough, titration can provided precise information about the value of dissolved CO2. In addition, when the ratio of molar concentration of NaOH to the molar concentration of CO2 is in the range of 1 to 2(equivalent to stoichiometric ratio of bi-carbonate and carbonat), the separability of the curves is enough...
Gas absorption enhancement in hollow fiber membrane contactors using nanofluids: Modeling and simulation
, Article Chemical Engineering and Processing: Process Intensification ; Volume 119 , 2017 , Pages 7-15 ; 02552701 (ISSN) ; Rahimi, M ; Molaei Dehkordi, A ; Sharif University of Technology
Elsevier B.V
2017
Abstract
In this article, a comprehensive 2D mathematical model has been developed to simulate process intensification of carbon dioxide absorption in the presence of nanoparticles in hollow fiber membrane contactors (HFMCs). The influences of nanoparticle were taken into account considering Brownian motion and Grazing effect as dominant phenomena of mass-transfer enhancement in nanofluids. The obtained simulation results were validated against experimental data reported in the literature and excellent agreement was obtained. It was found that by adding 0.05 wt % silica nanoparticles, the absorption rate could be enhanced by 16%, while the corresponding value is 32% for CNT nanoparticles. High...
Kinetic and Equilibrium Modeling of The Gas Adsorption on Adsorbent by Multilayer and Monolayer Adsorption Mechanism
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Cyrus (Supervisor) ; Jafari Behbahani, Taraneh (Supervisor)
Abstract
gas adsorption in porous solids and adsorbent,is the important cases in gas processing industries. Including the removal of compounds such as carbon dioxide, hydrogen sulfide and mercaptans from sour gas in natural gas sweetening industry is of great importance.Also in solving the greenhouse phenomena extraction of gases such as methane and carbon dioxide of important environmental issues.To understand and predict the behavior of the absorption capacity of various adsorbents and thus the possibility of absorption systems, a mathematical model is needed.Library resources available in order to determine the kinetics and thermodynamic processes of gas adsorption on solid absorbents use...
Modeling and Simulation of Gas Absorption in Hollow Fiber Membrane Contactors Using Nanofluids
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
Today, the usage of hollow membrane contactors is considered by the researchers as a novel solution in the separation and purification industry, including the sweetening of gas. Improving the performance of these devices requires a more detailed study of the process factors and changes in its chemistry. Hence, providing a suitable mathematical model by examining the details of the flow pattern within the contactor is based on the computational fluid dynamics technique in the agenda. Also, improving the absorption of components such as carbon dioxide and hydrogen sulfide from the gas mixture using chemical absorbents such as monoethanolamine will be investigated. The change in the mass...
Determination of Solubility and Density in Acidic Gas Absoption Systems by Ionic Liquids by Means of Cubic Equations of State
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Cyrus (Supervisor) ; Jalili, Amir Hossein (Supervisor)
Abstract
Due to their low volatility, negligible flammability, and high regeneration capacity, ionic liquids have attracted a lot of attention in chemical and process engineering fields. Regarding the limited access to the laboratory facilities, developing theoretical methods such as equations of state is important in this research field. Thus, data for density and viscosity of pure ionic liquids and vapor pressure data for binary mixtures of ionic liquids and acidic gas have been collected and validated from the IL Thermo website for 42 ionic liquids. By consideration of theoretical studies and comparison of the performance of different cubic equations of state in predicting the aforementioned...
Study of Absorption Enhancement of CO2 by SiO2, Al2O3, CNT, and Fe3O4 Nanoparticles in Water and Amine Solutions
, Article Journal of Chemical and Engineering Data ; Volume 61, Issue 4 , 2016 , Pages 1378-1387 ; 00219568 (ISSN) ; Keshavarz, P ; Ayatollahi, S ; Sharif University of Technology
American Chemical Society
Abstract
In this work, the absorption process of carbon dioxide is performed in a custom designed high pressure experimental setup in which the gas and nanofluid are in direct contact at static state in a closed vessel. The initial condition of the tests are set at 20, 30, and 40 bar and 308 K. Nanoparticles of SiO2, Al2O3, Fe3O4, and carbon nanotubes (CNTs) are dispersed in pure water to form nanofluids at concentrations of 0.02, 0.05, and 0.1 wt %. Also, CNT nanoparticle has been dispersed in methyldiethanolamine and diethanolamine aqueous solutions at the concentration of 0.02 wt %. The absorption performances of different nanofluids are compared with the base solutions and with other nanofluids...
Gel-sol synthesis and aging effect on highly crystalline anatase nanopowder
, Article Bulletin of Materials Science ; Volume 34, Issue 6 , October , 2011 , Pages 1189-1195 ; 02504707 (ISSN) ; Askari, M ; Sadrnezhaad, S. K ; Sharif University of Technology
2011
Abstract
Highly crystalline TiO 2 anatase nanoparticles were synthesized via gel-sol method by using titanium isopropoxide and triethanolamine. The products were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric/differential thermal analysis and nitrogen gas absorption methods. The particle size ranged from 7 to 24 nm having specific surface area of 64 to 220 m 2/g. Selective Ti(OH) 4 gel specifications and hydrothermal test conditions resulted in thermodynamically- stable phase-formation. Aging at 130°C for 4 h resulted in particle size of 7 nm; while at 130 and 160°C for 12 h resulted in 12 and 21 nm, respectively
Simulation of SO2 absorption in a venturi scrubber
, Article Chemical Engineering Communications ; Volume 197, Issue 7 , Feb , 2010 , Pages 934-952 ; 00986445 (ISSN) ; Mohebbi, A ; Taheri, A ; Sharif University of Technology
2010
Abstract
In this study, a three-dimensional mathematical model, based on a nonuniform droplet concentration distribution, has been developed to simulate gas absorption in a venturi scrubber. The mass transfer process was illustrated by assuming the liquid phase as a combination of droplets and film. The flow, just as the annular two-phase flow, includes a flow of liquid film layer on the walls and a flow of gas and liquid drops in the core. Peclet number was determined using experimental data reported by Viswanathan et al. (1984) for distribution of droplets across the cross section of the scrubber. The mathematical model for gas absorption was justified by comparing the theoretical predictions with...
Electroless plating of palladium on WO3 films for gasochromic applications
, Article Solar Energy Materials and Solar Cells ; Volume 94, Issue 2 , 2010 , Pages 201-206 ; 09270248 (ISSN) ; Tahmasebi Garavand, N ; Mahdavi, S. M ; Iraji Zad, A ; Sharif University of Technology
2010
Abstract
Nowadays, gasochromic Pd/WO3 coatings as optically switchable materials during H2 absorption have become more interesting due to their novel applications in smart windows and gas sensor devices. In this study, WO3 films were fabricated by Pulsed Laser Deposition (PLD) on glass substrates. Using an electroless method, Pd nanoparticles were deposited on the surface of the produced films. The effect of Pd growth time on coloring/bleaching rate was studied for different submerging times (1, 2, 5, 10, 15, 20 and 40 min). The best coloring/bleaching velocity was attained with a growth time of 2 min. The effect of growing time and growth feature of Pd particles was further studied using Scanning...
Thermoeconomic analysis and optimization of post-combustion CO2 recovery unit utilizing absorption refrigeration system for a natural-gas-fired power plant
, Article Environmental Progress and Sustainable Energy ; Volume 37, Issue 3 , 2018 , Pages 1075-1084 ; 19447442 (ISSN) ; Soltanieh, M ; Romeo, L. M ; Sharif University of Technology
John Wiley and Sons Inc
2018
Abstract
Exergy and exergoeconomic analyses have been used to set out weaknesses of the postcombustion CO2 capture unit of Besat power plant that uses an ammonia absorption refrigeration system for CO2 liquefaction. The energy required for the absorption system is provided by the flue gas. The liquefied CO2 is used for beverage and food industries. The exergoeconomic costs of all utility streams and processes are calculated through a systematic method of assigning exergetic cost relations to the streams. The results point out that the exergy destruction of the CO2 stripper and absorber columns are the highest, and according to the cost-based information, potential locations for the process...
Thermal radiation transfer calculations in combustion fields using the SLW model coupled with a modified reference approach
, Article Journal of Quantitative Spectroscopy and Radiative Transfer ; Volume 205 , 2018 , Pages 105-113 ; 00224073 (ISSN) ; Abrar, B ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The spectral-line weighted-sum-of-gray-gases (SLW) model is considered as a modern global model, which can be used in predicting the thermal radiation heat transfer within the combustion fields. The past SLW model users have mostly employed the reference approach to calculate the local values of gray gases’ absorption coefficient. This classical reference approach assumes that the absorption spectra of gases at different thermodynamic conditions are scalable with the absorption spectrum of gas at a reference thermodynamic state in the domain. However, this assumption cannot be reasonable in combustion fields, where the gas temperature is very different from the reference temperature....
An investigation on the influence of milling time and calcination temperature on the characterization of nano cerium oxide powder synthesized by mechanochemical route
, Article Materials Research Bulletin ; Volume 47, Issue 11 , 2012 , Pages 3586-3591 ; 00255408 (ISSN) ; Amoozegar, Z ; Sadrnezhaad, S. K ; Sharif University of Technology
2012
Abstract
The synthesis of nano-sized CeO 2 powder was investigated via mechanochemical reactions between hydrate cerium chloride and sodium hydroxide as the starting materials. The process was followed by a subsequent calcination procedure. Characterization of as-synthesized powder was performed using X-ray diffraction, FTIR spectroscopy, Brunner-Emmett-Teller (BET) nitrogen gas absorption, scanning electron microscopy (SEM) and particle size analyzer (PSA). The precursors were milled for different milling times and then were subjected to different heat treatment procedure at variable temperatures from 100 to 700 °C. According to the results, milling time and calcination temperatures induce...
Exergoeconomic optimization of a trigeneration system for heating, cooling and power production purpose based on TRR method and using evolutionary algorithm
, Article Applied Thermal Engineering ; Volume 36, Issue 1 , 2012 , Pages 113-125 ; 13594311 (ISSN) ; Saidi, M. H ; Ahmadi, P ; Sharif University of Technology
2012
Abstract
In the present study, exergoeconomic optimization of a trigeneration system for cooling, heating and power purposes has been carried out. The system is made up of air compressor, combustion chamber, gas turbine, dual pressure heat recovery steam generator and absorption chiller in order to produce cooling, heating and power. The design parameters of this study are selected as: air compressor pressure ratio, gas turbine inlet temperature, pinch point temperatures in dual pressure heat recovery steam generator, pressure of steam that enters the generator of absorption chiller, process steam pressure and evaporator of the absorption chiller chilled water outlet temperature. The economic model...