Sharif Digital Repository

Emission control, especially Carbon Monoxides (CO) as one of the major by-products of combustion processes, is one of the most serious challenges in burning waste-gases with high amounts of humidity and Carbon Monoxide. We investigated an oil waste-gas incinerator serving to a bitumen production line located in Pasargad Oil Company, Shazand, Arak, Iran. The aforementioned incinerator was criticized seriously for its high CO emissions. We were requested to find a solution to reduce the undesirable CO emission from that. Following the environmental standards, there is an upper limit of 150 ppm for the CO produced by an industrial waste oil incinerator. To present an inclusive solution for such... 

Incineration of oil wastes is a very important subject in oil refinery Industries. Such wastes may include toxic ports such as CO or hydrocarbon compounds, in either liquid or gas forms. In this project, we simulate an oil refinery incinerator. The industry has decided to increase the waste capacity to 150% of its design conditions. This causes the appearance of CO and methane at the outlet of incinerator stack. We investigated the incinerator operation and-found that we might solve the pollution problem by re-design of air and waste inlets to the incinerator. In this regard, we first simulated the incinerator in its normal operation to validate our numerical modeling. Next, we assumed... 

Dissemination of an analyte under the laminar flows plays a major role in measuring and assessment of biological fluids such as sample preparation in the context of microfluidic systems. Due to the development of manufacturing technology in the Lab-on-a-chip devices, the production of rectangular microchannels with finite aspect ratios and micron and submicron sizes has been provided by which the effect of electrokinetic phenomena on concentration distribution will be magnified in these systems. On the other hand, these biofluids are viscoelastic and show extraordinary flow behaviors, not existing in Newtonian fluids and adopting appropriate constitutive equations these exotic flow behaviors... 

Because of unique features and numerous advantages, the fluidized bed has been considered as one of the most widely used process equipment in various industries. However, many aspects of the hydrodynamic behavior of the equipment are unknown. In this study, using simulation tool, hydrodynamic behavior and mixing process of binary solids particle mixture in the tapered fluidized bed with a jet at the entrance were studied. Eulerian – Eulerian multifluid model incorporating the kinetic theory of granular flow is used to simulate the gas-solid multiphase flow with open-source MFIX software. To increase the accuracy of the results standard k-ε turbulence model was used. Validation of results was... 

This thesis tries to suggest a simple solution to reduce the amplitude of occurred fluctuations in mixing tees. Temperature fluctuations can induce cyclical thermal stress and thermal fatigue. In order to estimate the lifetime of pipeline material and reduce the frequency and amplitude of these fluctuations, an accurate diagnosis of these fluctuations must be conducted. For this aim, a comparison between Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models was carried out to show the ability of LES model in prediction of temperature fluctuations. The effect of Peclet number on the amplitude was discussed. The effect of placing simple pipe segments and orifices to... 

Today, due to the decline of drinkable water, many desalination plants have been established and operated around the world. Disposal of these brines, which have higher density and temperature than receiving water, causes many environmental impacts. Industrial power plants discharge these effluents into the seawater body mostly as submerged jets due to their higher effectiveness. Many experimental researches have been done on the negative and positive buoyant jet that discharged form desalination plants. But a few numerical studies have been done with investigating the full Navior-Stokes equations and they have been flawed in modeling. For example, some of these models have been able to... 

High mixing efficiency and high liquid-liquid mass transfer rate are two key features of spinning disk contactors. This work presents the experimental investigation of mixing and liquid-liquid mass transfer characteristics in a new double coaxial spinning disks contactor. The micromixing efficiency was investigated using a standard system of competitive parallel reaction known as iodide/iodate test reaction. The influences of various operating conditions such as the rotational speed of the disks, the direction of rotation, the feed radial location, the feed distribution pattern, the distance between the disks, and the feed flow rate on the mixing quality were examined carefully. The obtained... 

Urmia Lake is a strong electrolyte containing various salts, with a thermodynamic identity. Changes in the temperature and volume of lake water cause a change in the concentration of ions in this brine as well as the composition and precipitation of salts in the lake. As a result of these changes, the thermodynamic properties of brine are also changed. The purpose of this study was to investigate the effect of mixing the rivers entering the lake and calculate and analyze the changes in the quality and hydrogeochemical characteristics of Urmia Lake and the amount of precipitation and dissolution of the main minerals in Urmia Lake during the period of 2007-2013 per month. For this purpose,... 

The main objective of this study is a numerical simulation of flow and mixing behavior of two miscible liquids in a new static mixer over the Reynolds number in the range of 20-160. The performance of the proposed static mixer has been compared with the well-known three different static mixers namely, Kenics, SMX, and Komax. Pressure drop ratio (Z-factor), a coefficient of variation (CoV) and extensional efficiency (α) characteristics were, respectively, used to evaluate power consumption, distributive mixing and dispersive mixing performances in all static mixers. Since there are no experimental data for examined mixers, firstly, the CFD model was validated with measured data of the... 

This research aimed at production of Cu-rGO via the combination of Molecular-Level-Mixing (MLM) method and powder metallurgy route (PM). First, Cu-GO composite powder was produced via MLM method. Subsequently, the resultant powder was mixed with electrolytic copper powder.Synthesis process included adjustment of the solution containing copper sulfate and 2Na.EDTA using NaOH solution. In the next step, GO suspension was added to the aforementioned solution. Finally, reduction of copper powder and formation of nanocomposite powder completed via the addition of Sodium Borohydrate. Nanocomposite powder was washed and dried in vacuum oven in 70˚C. GO reduction process took place using a tube... 

The process of gas injection is well-known for Enhanced Oil Recovery (EOR) among researchers in the past few decades. This process depends on both compositional effects and IFT reduction effects as the conditions approach miscibility. This study seeks to evaluate the interactions of these two fundamental mechanisms in the process of enriched gas injection for EOR. At first, we investigate the relative dominance of the key mechanisms, as well as composition paths, component and phase distribution, and component production via compositional simulation of the process of gas injection into 1D homogeneous porous media such as slim tube and core under immiscible and near-miscible conditions. Then,... 

Motivated by the role of interfacial instabilities in sediment resuspension, this paper provides quantitative measurements of the long-time behavior of the interfacial waves and the changes in vertical density during motion of a surface wave over a muddy bed. After an initial fluidization process, a 3D quasi-standing interfacial wave was observed at the interface as a result of a resonant wave interaction with the surface wave. In the process, the quasi-standing wave started growing exponentially at a rate of 0.052-0.081 1/s and then reached a maximum amplitude (kexpb=0.77-0.83). The interfacial wave then took a downward trend in the transition stage and approached a steady state... 

Due to environmental concerns about fossil fuels energy sources, countries are striving to replace fossil fuels with renewable energy sources. However, most alternative energy sources are highly dependent on weather and seasonal conditions. Underground hydrogen storage (UHS), unlike carbon dioxide storage which only experiences the gas injection phase, involves injection and production cycles. Therefore, it faces different challenges, each of which has different effects on the final hydrogen recovery rate and, consequently, cost estimation. Some of the major challenges ahead include the reservoir structure, heterogeneity of reservoirs, selection of suitable cushion gas, the impact of the...