Sharif Digital Repository

One of the encouraging technologies for resolving the lack of clean water in the world is forward osmosis process (FO). Reaching to a optimized development of FO membranes is essential to make fo process commercially viable.
This study’s aim is to develop a thin film composites (TFC) membrane with high FO performance (good water flux and high salt rejection) in order to seawater desalination.
Polyacrylonitrile (PAN), a hydrophilic polymer, is a less considered polymer in fabricating support layer for TFC FO membranes .TFC membranes consist of a selective polyamide active layer formed by interfacial polymerization on top of a support layer fabricated by non-solvent induced phase... 

In this research, we focus on reduction of solutes in left out water from reverse osmosis membranous units (brine) with reduction of scaling factors of membrane. This research is important from that perspective that the out put brine from reverse osmosis membranous unit After purification by this method, enter into membranous system in order to increase in recovered water volume and also minimization of out put waste from membranous system and decrease the environmental damages. The method used in this research, is three processes of cooling, chemical desalination and seeding by crystal material. In this research is investigated the type and amount of matter for chemical desalination and... 

The design and optimization of processes was focused in the past on economic issues such as profitability and return on investment, and less attention has been paid to environmental issues. In recent years, by introducing environmental criterion as pillars of sustainable development, environmental optimization of processes has becoming an inseparable element of the process engineering. Therefore, it is necessary to examine the compatibility of environmental indicators with economic objective. The purpose of this study is to investigate environmental indicators and economic objective function in optimizing the Crude Distillation Unit (CDU) of an oil refinery. The CDU is one of the most... 

Desalination of seawater is one of the best solutions for freshwater supply. Solar desalination is an appropriate way to desalinate seawater. The main disadvantage of solar desalination systems is low daily production. Considering the free radiative cooling potential, the purpose of this project is the increment of the daily yield of solar still by enhancement of condensation process. For transferring cooling potential of radiative cooling from nighttime to the daytime, phase change materials (PCMs) are used. Two types of condensers are fabricated in this project. One of them uses ambient air as a thermal sink and the other one uses radiative cooling which is saved in PCM. Describing... 

In present research work, methods of preparing ion exchange membranes, especially anion exchange membranes, were studied and chemical modification of polysulfone was chosen as a safe and economical method for preparing anion exchange membranes. The chloromethylated polysulfone was characterized by HNMR spectroscopy and functionalization degree was determined according to peak area integration. Membranes were produced by mixing and amination of the chloromethylated and normal polysulfone (40-100% wt). Morphology and chemical structure of membranes were investigated by SEM images and FTIR spectroscopy.The ionic conductivity, ion exchange capacity and water content of samples were measured. The... 

With regard to an increasing world population and the constant capacity of water resources, new and valid methods should be implemented to preserve freshwater resources and accordingly produce drinking water. In the present study, a solar hybrid system was studied by experimental and theoretical means to facilitate the transformation of waste heat from photovoltaic module (PV module) into useful heat that can be used in a solar desalination (SD) system for freshwater production purposes. The study aimed to fabricate a SD system by using both PV module and thermosyphon heat pipes (THPs) technologies in a single system. In the modeling section, the goal is to present a comprehensive model... 

In this investigation the thermodynamic, economic and environmental analysis of a 4rth generation system for simultaneous produce of heat, power, water and cooling of a residential building in Tehran-Iran has been done. Four different system have been used for power generation: 1-combined cycle of Direct Internal Reforming Solid Oxide Fuel Cell and Gas Turbine (IRSOFC-GT) 2-combined cycle of Gas Turbine and Steam Turbine (GT-ST) 3- cycle of Gas Turbine with Recuperator (GT-R) 4- cycle of Steam Turbine (ST). A double effect absorption chiller has utilized to provide the cooling load of the building, while a heat exchanger provides its thermal requirement. Also a MED-TVC system was used to... 

With the depletion of fossil resources, price of these energy careers increases. Therefore, researchers investigate for other alternative choices. One of the most interesting choice is the renewable energies. These sources of energies are attractive due to either they are permanent resources or they are environmentally friendly. The most important renewable energy resource is solar energy that in fact is the source of other renewable energies. The most important and economic method of solar energy absorption is the thermal method. Common technology in thermal method is the Parabolic-Trough. But, recently a new technology have been developed called Compact Linear Fresnel Reflector (CLFR) that... 

The subject of this thesis to assessment environmental impacts of active desalination plants in Kish Island, which explains the problems derived from concentrate discharges in to the sea, sewage network, absorbing wells and ground surface.
It also studies its impacts on land and marine ecosystem and underground aquifers that are strategic resources in Kish Island. In addition, the environmental studies done in other countries, the existing regulations and by laws in the field of environmental impacts of desalination plants and concentrate discharges are re-mentioned. Concentrates contain chemicals, which are used in pre-filtration of MED and Ro systems, which are dangerous for marine... 

The present thesis aimed to study a novel heat pump integrated humidification-dehumidification (HDH-HP) desalination system. A theoretical outline was proposed for the first time to examine the design and off-design performance of HDH-HP cycles via the compressor characteristics method. In this regard, the variations in heat pump performance were modeled in different operating conditions for a fixed-size system. To fabricate a compact HDH-HP system, an evaporative condenser was designed and used instead of a separate humidifier, heater, and air/water-cooled condensers find in previous HDH-HP systems. Meanwhile, the air dehumidification process in this work directly occurred inside the heat... 

The current work studies the economic investigation of reverse osmosis (RO) desalination unit and multi-effect distillation (MED) considering the average global and also Iran circumstances. Technical and operational parameters are taken into account for economic modeling of both methods to choose the proper and economic method for water desalination based on different operational conditions. The cost of the desalination plants is investigated in two different parts of capital cost and operating and maintenance cost. Capital cost is divided into direct and indirect cost subsections. Based on these calcifications, the effect of economic parameters on change of capital cost and operating and... 

The scarcity of potable water is one of the world's challenges. In the Middle East, this crisis is even worse and as a consequence, the most aggregation of desalination plants has been constructed in this area. However, brine effluent discharged from these plants entails serious environmental issues. Despite the extensive studies about the investigation of dilution and the area which faces the brine discharges as submerge jets, there are a few experimental investigations with a focus on the injecting brine discharge into the shallow environment. Whereas the Persian Gulf's coastal environment is shallow. Moreover, there is a huge construction of desalination held in this area. Accordingly,... 

The sea's ecosystem is the most sensitive and essential as the last recipient of sea and land pollution. The increasing requirement for building thermal power plants and desalination plants and a great demand for their thermal effluents discharge causes a serious threat to the rich coastal environment. In this project, a general study on environmental and meteorological data required to investigate the environmental effects of effluent discharge from desalination plants in the Persian Gulf and the Sea of Oman has been conducted, and the general process of conducting thermal effluent discharge research in this area is presented. Next, in a case study using MIKE hydrodynamic software and... 

Agriculture is one the most water consuming sections in the world and roughly 60% of water demand is dedicated for this purpose. A seawater greenhouse manages to combine fan and pad greenhouse with humidification-dehumidification desalination in order to achieve water production next to agriculture products using moister in air which was used for cooling. The most important aspect of a seawater greenhouse is the amount of produced water. Many research on the condenser type and materials have been conducted in order to achieve a better performance, suggesting the utilization of a low temperature water source for the condenser. In this research, using a thermodynamic correlations to model the... 

Providing fresh water for domestic and agricultural purposes has become one of the most pressing issues of the present century. Due to the dependency of conventional desalination on fossil fuels, these methods are associated with carbon dioxide and other greenhouse gas emissions. Therefore, renewable energy-based desalination systems have come to the fore. This study scrutinizes the performance of the solar Humidification-Dehumidification (HDH) desalination systems with subsurface condensers. In this system, solar energy evaporates water, and subsurface condensers condense water vapor into fresh water. Therefore, this system uses two renewable solar and geothermal energy. Due to the lack of... 

Water is the most essential human need and the lack of fresh water soon is one of the biggest problems of mankind. One way to deal with the lack of fresh water is desalination of seawater. Seawater desalination is done by different thermal and membrane methods. In this research, the methods and history of freshwater supply methods and the role of chains in the progress of seawater desalination, and the measures taken in the field of seawater desalination have been investigated. Among the various methods discussed and proposed in this research, it was concluded that reverse osmosis membrane is available and has an acceptable economic efficiency compared to other methods. After choosing the... 

The solar-driven humidification-dehumidification desalination system with a geothermal dehumidifier (SD-HDH-GD) has been given special attention, for producing drinking water and subsurface irrigation applications. This contribution scrutinizes the performance of the geothermal dehumidifier of the SD-HDH-GD system. To this aim, a comprehensive three-dimensional transient computational fluid dynamics model of the geothermal dehumidifier and the surrounding soil is developed. An experimental setup is established to verify the developed numerical model. At first, the performance of the system in a short-term period of 12 hours is investigated, and the effect of several operation parameters is... 

The world's freshwater resources are rapidly decreasing due to population growth, industrial and technological progress, successive droughts, climate changes, increased food demand, and poor management of water resources. Using desalination methods is one of the ways to produce the required freshwater. Several methods have been developed for desalination. The most widely used method is reverse osmosis (RO). In this thesis, an electrodialysis (ED) desalination system was designed and modeled using up-to-date and reliable articles. This modeling was done in EES software and after validating that, the effect of considering Donnan's potential was investigated. At the 60 ppt concentration of the... 

According to current researches, graphene oxide (GO) membranes show promising desalination properties due to ease of synthesis, low production cost, and high efficiency. There are several experimental works to study ionic sieving properties of GO membranes. However, it is difficult to characterize atomistic mechanism of water permeation and ion rejection by experimental approaches. On the other hand, there exist a few reports in which the atomistic picture of water permeation across GO membranes is investigated by means of molecular dynamics (MD) simulation. In the present work, in addition to water desalination, the atomic scale mechanism of ion rejection is studied using large scale MD... 

Reverse osmosis (RO) is by far the most widely used membrane desalination process worldwide. The RO process depends on the properties of semi-permeable membranes which allow the separation of water from a salt solution by applying external pressure higher than the osmotic pressure on the seawater. The main problem in membrane separation process is the fouling of the membrane walls, which decreases the permeate flux. Having spacer filaments in the feed channel has been proven to dynamically change the concentration boundary layer and preventing fouling. The impact of spacer configurations (cavity, zigzag and submerged) on the alleviation of concentration polarization and the enhancement of...