Sharif Digital Repository

In this work, desalination of saline brines using the sweeping gas membrane distillation (SGMD) process is investigated. The Taguchi method was applied for optimization of the operating parameters. An L9 orthogonal array was used to investigate the influence of pertinent variables, including feed temperature (Tf: 45°C, 55°C and 65°C), feed flow rate (Qf: 200, 400 and 600 mL/min), feed concentration (Cf: 10, 25 and 50 g/L) and sweeping gas flow rate (Qc: 4, 10, and 16 SCFH) on the distillate flux. Results of the experiments showed that maximum distillate flux, which was about 10 L/m2 h, obtained at 65°C feed temperature, 16 SCFH sweeping gas flow rate and brackish water with 10 g/L salt... 

In the present work, the roles of inorganic oxide nanoparticles on the extraction efficiency of polyethylene terephthalate-based nanocomposites were extensively studied. Four fiber coatings based on polyethylene terephthalate nanocomposites containing different types of nanoparticles along with a pristine polyethylene terephthalate polymer were conveniently electrospun on stainless steel wires. The applicability of new fiber coatings were examined by headspace-solid phase microextraction of some environmentally important volatile organic compound such as benzene, toluene, ethylbenzene and xylene (BTEX), as model compounds, from aqueous samples. Subsequently, the extracted analytes were... 

Reinforced polydiphenylamine (PDPA) nanocomposite was synthesized by oxidation of diphenylamine in 4molL-1 sulfuric acid solution containing a fixed amount of carbon nanotubes (CNTs) in the presence of cetyltrimethylammonium bromide (CTAB). The surface characteristic of PDPA and PDPA/CNT nanocomposites was investigated using scanning electron microscopy (SEM). The prepared PDPA/CNT nanocomposite was used as an extraction medium for microextraction in packed syringe (MEPS) of selected pesticides from aquatic environment. The effect of CNT doping level and the presence of surfactant on the extraction capability of nanocomposite was investigated and it was revealed that when 4% (w/w) of CNT in... 

Wettability is one of the most important factors which significantly influences solar still efficiency. Moreover, it determines the condensation mode, i.e., filmwise or dropwise condensation. In the present study, materials with different wettability were applied as the condensing surface to evaluate the effect of wettability on the distillate production of a single slope solar still. To compare the effects of dropwise and filmwise condensation on the condensate yield, the wettability of the condensing surface was changed by applying a nano-silicon solution according to a dip coating technique. All the experiments were conducted at three surface inclination angles. The results revealed that... 

Due to the increasing need for drinking water in the world, various membrane processes have been developing significantly over the past several years. The process of membrane distillation is one of the non-isothermal processes that cause steam to pass from the membrane due to the difference in temperature and the resulting difference in vapor pressure. Due to the lack of precision in the amount of flux and thermal efficiency in various operating conditions the membrane distillation process still needs development. This article attempted to examine the effects of flowrate, temperature, and module length on the performance of the membrane distillation process using computational fluid dynamics... 

It is well known that the oil recovery is affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of medium surfaces has remained a topic of debate in the literature. Furthermore, there is a little information of the way dispersed silica nanoparticles affect the oil recovery efficiency during polymer flooding, especially, when heavy oil is used. In this study, a series of injection experiments were performed in a five-spot glass micromodel after saturation with the heavy oil. Polyacrylamide solution and dispersed silica nanoparticles in polyacrylamide (DSNP) solution were used as injected fluids. The oil recovery as well as fluid distribution in... 

Photothermally heated and mesh-gridded membrane distillation (PHMD) system is proposed for desalination of high saline aqueous solutions. A triple-layered membrane, composed of a photothermal top nanofibrous layer containing polyacrylonitrile and dispersed carbon black nanoparticles and a polyvinylidene fluoride porous membrane supported on a nonwoven polyester, was prepared. A polypropylene mesh was used to hold the membrane. A 3D numerical simulation of the PHMD system was carried out by COMSOL and the appropriate length of the membrane module was determined. The effects of various operating parameters including solar radiation intensity on the permeate flux and thermal efficiency were... 

In the present work, effects of height, length, and width of a single-slope basin-type solar still on its distillate production was investigated. For this purpose, a radiation model was developed which accounts for the influences of all walls on quantities of received solar radiation by the base and saline water of the still. Moreover, in this radiation model, the side walls of the still were considered as the trapezoid and the diffuse as well as beam components of solar irradiance were separately taken into account for the first time. Abilities of the present model were compared with earlier ones. Furthermore, the predictions of the current model were compared with the present experimental... 

In recent years, there has been a great tendency to optimize energy consumption in the oil and gas industry’s upstream and downstream equipment. One of the most energy-intensive processes in natural gas refineries is the condensate stabilization unit (gas condensate). The main bottlenecks of energy consumption in the old units are condensated stabilization (dehumidification with ethylene glycol), heater reboiler, and air coolers (air coolers). Therefore, much attention should be paid to these applications and electricity and steam consumption in this unit. In this study, a simulated model based on the Gachsaran gas refinery’s new layout has been developed. Optimization of this part of the... 

Extended Kalman Filtering (EKF) is a nonlinear dynamic data reconciliation (NDDR) method. One of its main advantages is its suitability for on-line applications. This paper presents an on-line NDDR method using EKF. It is implemented for two case studies, temperature measurements of a distillation column and concentration measurements of a CSTR. In each time step, random numbers with zero mean and specified variance were added to simulated results by a random number generator. The generated data are transferred on-line to a developed data reconciliation software. The software performs NDDR on received data using EKF method. Comparison of data reconciliation results with simulated... 

Used lubricating oil (ULO) is a heavy mixture of various hydrocarbons and needs to be treated before discharging. Considering ULO nature, it is more favorable to recover lighter hydrocarbon cuts from ULO, which not only improves the whole process economically, but also prevents the emission of hardly decomposable hydrocarbons into the environment. In this research, the potential of pyrolysis method for ULO recovery was studied. Furthermore, graphene nanoplatelets (GNP), γ- Fe2O3 and ZnO nanoparticles were used to improve the kinetics of the process and their impacts on the final product quality were evaluated. Based on the results, adding nanomaterials increased the tendency to produce gas... 

Solar stills are considered an environmentally friendly technique to produce fresh water. The condensation surface plays an essential role in controlling the efficiency of the solar still. This main parameter is critically affected by the wettability of the condensation surface that affects the condensation mechanism, namely drop-wise or film-wise condensation. This study aims to enhance the efficiency of solar stills by altering the surface wettability hence changing the condensation mechanism using nanomaterials. In this experimental work, different condensation surfaces were coated by silicone nanoparticles to change the condensation mechanism from film to dropwise. Scanning electron... 

It is well known that the displacement efficiency of EOR processes is mainly affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of pores surfaces remains a topic of debate in the literature. Furthermore, a little is known about how the dispersed silica nanoparticles affect the microscopic/macroscopic recovery efficiency of heavy oils during common immiscible EOR processes such as water flooding. In this study, a series of injection experiments was performed on five-spot glass micromodel which is initially saturated with the heavy oil. Distilled water and dispersed silica nanoparticles in water (DSNW) at different values of weight percent... 

It is well known that the displacement efficiency of EOR processes is mainly affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of pores surfaces remains a topic of debate in the literature. Furthermore, a little is known about how the dispersed silica nanoparticles affect the microscopic/macroscopic recovery efficiency of heavy oils during common immiscible EOR processes such as water flooding. In this study, a series of injection experiments was performed on five-spot glass micromodel which is initially saturated with the heavy oil. Distilled water and dispersed silica nanoparticles in water (DSNW) at different values of weight percent... 

In this article the methodology proposed by Li and Wang for mixed qualitative and quantitative modeling and simulation of temporal behavior of processing unit is reexamined and extended to more complex case. The main issue of their approach considers the multivariate statistics of principal component analysis (PCA), along with clustered fuzzy digraphs and reasoning. The PCA and fuzzy clustering provide tools to categorize the quantitative dynamic trends, describing the temporal behavior of joint human-process interactions qualitatively, and through the proposed neuro-fuzzy reasoning the system responses can be obtained when the system is exposed to uncertain disturbances. First, the method... 

The resistance and capacitance values of the water samples are measured by using two different cell probes (length 10 cm and 5 cm) and a measuring module. Measured conductivities for the different water samples are compared where the lowest conductivity is obtained for the distilled water (3.28 μS/cm) and the highest value is for the boiled water 325.91 μS/cm. Using the measured series resistance values, and by knowing the frequency (1 kHz), the imaginary part of permittivity value is also determined. The imaginary part of the permittivity for the distilled water with the long cell probe is about 0.524 × 10 -7 F/m (for the short probe is 0.523 × 10-7 F/m) while for the boiled water sample is... 

Biosurfactant production through a fermentation process involving the biodegradation of soybean oil refining wastes was studied. Pseudomonas aeruginosa MR01 was able to produce extracellular biosurfactant when it was cultured in three soybean oil refinement wastes; acid oil, deodorizer distillate and soapstock, at different carbon to nitrogen ratios. Subsequent fermentation kinetics in the three types of waste culture were also investigated and compared with kinetic behavior in soybean oil medium. Biodegradation of wastes, biosurfactant production, biomass growth, nitrate consumption and the number of colony forming units were detected in four proposed media, at specified time intervals.... 

In the present experimental study, the effect of operating parameters such as inlet and outlet pressure as well as inlet temperature on the mass separation capability of vortex tubes (VTs) for a gas mixture is investigated. Specifically, concentrating heavier components of a gas mixture in the hot outlet stream is considered. Proposing a semi-empirical index from the experimental study, the simulation of different arrangements of VTs, and the effect of recycling a portion of the hot outlet stream on its mass separation performance are investigated. Moreover, the proposed separation method by VTs is economically compared with commonly used methods by distillation columns and two-phase... 

Low Grade Heat Driven Multi-effect Distillation and Desalination describes the development of advanced multi-effect evaporation technologies that are driven by low grade sensible heat, including process waste heat in refineries, heat rejection from diesel generators or microturbines, and solar and geothermal energy. The technologies discussed can be applied to desalination in remote areas, purifying produced water in oil-and-gas industries, and to re-concentrate process liquor in refineries.
This book is ideal for researchers, engineering scientists, graduate students, and industrial practitioners working in the desalination, petrochemical, and mineral refining sectors, helping them... 

In this study electrical properties of different water liquids at frequency range of 100-2000 Hz are investigated by using the short invasive and non-invasive cylindrical capacitive sensors (CCSs). Operation of the capacitance measurement module for such probes is based on the auto balancing bridge method. Comparison of the measured capacitances and measured resistances for different water liquids shows decrease by increasing the frequency. In another study the dielectric constant of distilled water, mineral water, tap water and salt water are measured. The effects of the frequency on the resistivity, permittivity and conductance of the different water liquids are also investigated