Sharif Digital Repository

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,... 

In this research energy and exergy Balance has been studied for a turbocharged three-cylinder engine. Energy balance is a method based on the first law of thermodynamics and based on this method the control volume is selected on the engine and the input and output energies of the control volume are calculated. Exergy balance is also a method based on the second law of thermodynamics which achieves the amount of irreversibility and ability to convert useful work for different energies in the control volume. In the tests performed, the net output power, output exhaust energy, energy transferred to the cooling fluid and other energies, including convection and radiation heat transfer from the... 

Access to potable water with standard quality is an inevitable component of human’s lives. Seawater desalination is the precedure of removing the impurities and contaminants in water to achieve the suitable quality for human consumption. Freeze desalination, by consuming relatively much lower energy compared to other techniques has shown to be a promising method for desalination. This technique requires the exertion of a cold source to the system which is then accompanied by simultaneous rejection of the impurities from the water. Regarding this, a numerical study on freeze desalination a hollow cylinder is carried out to determine the effects of the design variables such as heat flux,... 

Co-culture of different cells is necessary for cancer spheroid formation in preclinical drug tests. It is possible to produce thousands of micro-droplets containing different cells, i.e. microcapsules, in a short time, using droplet microfluidics. However the homogeneity of the cell numbers in the droplets has remained as an unsolved problem.Despite the large amount of experimental efforts to reduce the number of undesirable microcapsules, no one tried to utilize the ease of computer aided simulation for investigating different parameters. In this study, we develop a novel method for capturing cell encapsulation using CFD simulations. The effect of the cell suspension inhomogeneity and... 

Analytical biological research has gained significant attention due to the critical importance of processes such as cell separation, cell lysis, DNA purification, and amplification for disease diagnosis and genetic studies. These processes are essential in biological assays for molecular pathogen detection, immunological assessments, and studies on the effects of drugs on diseases. The objective of this research is to design and develop microfluidic systems in three main areas: cell separation, DNA extraction, and amplification for the identification of BRCA1 mutations. The cell separation platform is solely designed for simulation on a microfluidic chip, while the extraction and... 

In this thesis, engine performance parameters such as power, torque, fuel consumption and in-cylinder pressure are investigated with considering ignition timing in order to achieve the minimum value of knock index. The implemented methods include engine dynamometer tests and simulating vehicle powertrain in GT- POWER software. Based on the acceptable precision of the GT-POWER model, it can be used to predict the engine performance in other ignition timings. Final results prove that for wide open throttle status altering the ignition timing to reach the minimum possible value impact differently on the engine performance so that in low engine speeds for basic and new ignition timings, a... 

The application of internal combustion engine is vast in different context, such as transportation and power generation. Therefore to investigation of these objects and the importance of flame front development, a combustion chamber with constant volume is designed and manufactured. The chamber designing is based on the experimental knowledge and numerical simulation of chamber and glasses. The combustion chamber made of stainless steel and contained transparent quartz glasses in both side of it to provide the ability of using schlieren photography method and investigation of flame. The great advantage of present chamber is the capability of different type of combustion, including fuel and... 

In the present study, a 3D combustion chamber was simulated using FLUENT6.32. The objectives were to obtain detailed information on the combustion characteristics and NO formation in the furnace, and also to examine the effect of Oxygen enrichment on the combustion process. The combustion chamber has internal dimensions of 60 cm wide, 90 cm high and 190 cm long. The fuel pipe diameter is 1.25 cm and the air pipe diameter is 3.5 cm. The 3-D Reynolds Averaged Navier Stokes (RANS) equations together with standard k-ε turbulence model are solved by Fluent 6.3. Air/fuel flow rate ratio is varied as 1.3, 3.2 and 5.1 and the oxygen enriched flow rates are 28, 54, 68 lit/min. NO emission was... 

In this work, wind farm layout optimization problem is dealt with a new approach. The aim of this work is maximizing the output power of a wind farm by considering wake loses. Layout optimization minimizes the wake loses regarding the wind direction. Three different wind scenarios including different wind direction angles, wind direction blowing probabilities and Weibull distribution parameters for wind speed are assumed. Since, the problem is nonlinear and constrained, imperialist competitive algorithm is used as a modern and powerful algorithm for continuous optimization problems. The optimization outcomes indicate that imperialist competitive algorithm yields promising results.... 

Sustainable development is a general concept in all aspects of human life, including social, economic, environmental, etc. Since one of the pillars of achieving sustainable development is the optimization of energy consumption, and on the other hand, energy consumption in buildings accounts for one third of the country's annual energy consumption, so it is very important to provide solutions that can reduce energy consumption in this sector. Therefore, in this research, with the aim of optimizing energy consumption in buildings, examples in different climates of Iran are selected and effective strategies to reduce energy consumption are identified according to each climate and used to... 

Nowadays, nanotechnology has emerged in many processes; hence the construction of this scale is also important. By reducing the size of equipment, raw material consumption is reduced and less space is needed for equipment. In addition it is economical. LIGA method has the potential to make parts with small dimensions and accurate tolerances, that it is impossible with other methods (chemical vapor deposition, physical vapor deposition, bulk micromachining, surface Machining). It is possible to assemble the pieces by producing micro-molding in LIGA procedure.In this thesis, numerical simulation of electrodeposition that is one of the main steps in the LIGA procedure has been investigated. One... 

For optimum designing of dry friction clutch, we should taking into account a lot of parameters, in order to the clutch have good efficiency in torque transmission and power train. These parameters include: the type of friction plate and the mechanical properties, Clutch geometry, diaphragm spring and its ability to make pressure. In this project, the goal is the analysis of effect of different parameters in clutch's temperature distribution and effect of these issues in torque transmission. In next step, the clutch's temperature distribution analyzed by changing the friction plate (ceramic), pressure applied and relative round in order to gain optimum properties of clutch. These works done... 

The purpose of present work is to study the effect of different parameters on the solar chimney used in ventilation. Experimental model and numerical model were used to achieve this goal. First, the model was numerically analyzed by Fluent software using Boussinesq approximation. The results of numerical modeling were validated by the empirical model. Finally, the numerical model can be used to investigate the effects of parameters which modeling is not possible by the empirical model for any reason. Experimental modeling was performed on a chimney with height and width of 180 and 62 cm, respectively. The thickness and angle of chimney in both experimental and numerical methods varied from 5... 

Design hybrid systems to supply electrical energy for off grid domestic consumer in the remote villages in Iran are the main objective of this work. The hybrid systems considered in this study consist of photovoltaic array, wind turbine, battery and diesel generator. Measured wind speed data used for wind turbine energy production model. The hybrid system optimized to supply 6, 14, 20, 40 and 60 families in Bojnoord, Moorchehkhoort, Kish, Langrood, Khash and Meshkinshahr. The main purpose of optimization is to find the economic system, able to fulfill the energy requirements of a given load distribution; so Iran’s current economy and cost, considered. The optimized results for studied cities... 

The purpose of this study is to determine a function which estimate fuel/air equivalence ratio distribution inside combustion chamber of spark ignition engine for pollution minimization and maximum efficiency. To do this, we developed a code by which, we are able to model one SI engine cycle.
Seven distributions for fuel/air equivalence ratio were examined which include: Homogeneous, linearly decreasing, linearly increasing, sinusoidal increasing and decreasing, sinusoidal decreasing and increasing, cosinusodal decreasing, and cosinusodal increasing. The average fuel/air equivalence ratio for all of these distributions was 0.85.
The results for indicated power showed that,... 

Three-dimensional cell culture and forming multicellular aggregates is superior over traditional monolayer approaches due to better mimicking in vivo conditions and hence functions of a tissue. A considerable amount of attention has been devoted to devising efficient methods for the rapid formation of uniform sized multicellular aggregates. Restoring cartilage to healthy state is difficult due to low cell density and hence low regenerative capacity. Currently used platforms are not compatible with clinical translation and require dedicated handling of trained personnel. However, when engineering and implanting cell microaggregates in a higher concentration, new cartilage is efficiently... 

Droplet-based microfluidic logic gates have many applications in diagnostic tests and biosciences due to their automation and cascading ability. Although most biological fluids, such as blood, exhibit non-Newtonian properties, all previous studies in this field have been with Newtonian fluids. Additionally, none of the previous work has studied the functional area of logic gates. In the present work, AND-OR logic gate with power-law fluid is considered. The effect of important parameters such as non-Newtonian fluid properties, droplet length, capillary number, and geometrical properties of the microfluidic system on the operating region of the system has been investigated. The results show... 

Significant advances in biotechnology have led to the emergence of a cost-effective way with less ethical issues to study disease, organ functions, tumors, and their response to drugs besides studying on animals. Microfluidic devices and organ on a chip (tumor on a chip) were introduced to remove those obstacles. Organ on a chip is a powerful tool for studying different types of tissues and simulating diseases, especially cancers, for biological and medical applications. Organ (tumor) on a chip is considered as a smaller scale of the real organ or tumor and it causes to the real-time study of tissues and their functions more accurately. In this study, to fabricate a droplet-based... 

One of the critical challenges in droplet based micro- and nanofluidic devices is handling the droplet breakup such that a controllable droplet size is produced. The experimental and numerical investigations at the microscale indicate that the droplet size can be well controlled by T junction geometries. In the present study we use non-equilibrium molecular dynamics (NEMD) simulations to investigate this phenomenon at the nanoscale. In order to generalize the study the Lennard-Jones type potential between the fluids and the walls have been considered and the strength and the effective range of the potential are changed to consider a wide variety of materials. Our results reveal that the... 

Rapid growing use of energy resources in recent decades, caused to focus on combined heat and power generation systems according to their high efficiencies. Energy efficiencies with these technologies will be up to 90 percent. Some benefits of Co-generation systems are their high efficiencies, omitting of transmission and distribution lossesin the electricity grid, fuel consumption reduction, moving to ward privatization,independent and decentralized production of electricity and heat, increase competition in the power generation and reduction theemission of greenhouse gases, particularly carbon dioxide. In This article theeconomicsof combined heat and power generator stobe installed...