Sharif Digital Repository

Aerodynamical design of backward swept for a horizontal axis wind turbine blade has been carried out to produce more power. Computational Fluid Dynamics (CFD) calculations were used for solving the conservation equations in one outer stationary reference frame and one inner rotating reference frame, where the blades and grids were fixed in reference to the rotating frame. The Reynolds Averaged Navier-Stokes (RANS) solver was validated in a test case, the National Renewable Energy Laboratory (NREL) VI blades. Simulation results show considerable agreement with the measurements. Three different turbulence models have been compared: Spalart-Allmaras, the Standard K-ε, and Shear Stress Transport... 

Recently, a lot of attention has been devoted to the use of Darrieus wind turbines because of high power density and environment aspect in urban areas. Turbine airflows don’t effect on the power coefficient of Darrieus turbine. This turbine has an acceptable power coefficient depend on the other wind turbine in the small scale turbine. Aerodynamic performance of a Darrieus turbine is very complex due to phenomena such as dynamic stall and changing forces on the turbine caused by changing horizontal angles. So study airflows around turbine must be preformed. In this thesis the aerodynamics of an H-rotor vertical axis wind turbine (VAWT) has been studied using computational fluid dynamics in... 

Due to inherent dangerous on human and environment safety in the nuclear power plant has significant importance. In order to ensure the safety of the plant and proper functioning ofits various components,before its operational exploitation, a series of commissioning tests should be conducted according to international standards for nuclear power plants. In addition, safety of the plant can be guaranteed bymodeling of transient states and possible scenarios of accident in different situations.In this research,by gathering geometric data and information about the facilities installed in the plant, modeling of Commissioning test of Bushehr Nuclear Power Plant (BNPP) and its associated accident... 

High pressure natural gas is transported from processing plants to end users via a network of natural gas system. Pressure reduction along the transport system is compensated in compressor stations. High pressure natural gas flows in to distribution network in demand center which operates at medium pressure. Medium pressure gas is transferred to end users who can use natural gas with low pressure. Therefore, pressure of natural gas is reduced consequently when gas flows from transport systems to distribution network and end users. Work is dissipated during pressure reduction which otherwise could be converted in to power.A technology that could be utilized for conversion of pressure work in... 

Recently wind turbines with vertical axis attract attention of world’s scientific society to itself because of many reasons such as: ability to work in areas with high turbulency, structural simplicity, independency from wind direction, easy maintenance and low capital cost. So that major part of recent researches in context of wind turbines are about these turbines. In this project a small sample of wind turbine from darrieus type have been designed, manufactured and finally important parameters such as Pitch Angle, Blade numbers and Aspect Ratio have been investigated. Darrieus turbine with 4 Blades and Pitch Angle of +15° was the most appropriate sample between the test samples. In the... 

Considering the increasing growth of population and the economical development in our country, the need to drinking water as well as agricultural water sources is felt more. In this respect and with regard to the lack of water sources in central and southern parts of our country, the present project suggests a system which can be used in south of the country to produce desalinated water from the salt water of sea. This system is recommended due to the comparative advantages of the southern part of the country including the prevalence of gas turbine plants, proper solar insulation and the access to salt water. The system is suggested with the presupposition of accessibility to a working gas... 

Gas turbine is one of most widely used in power plants to generate electricity or mechanical power options in the industry , which is having its own advantages and disadvantages . if the turbine use simple , efficiency is generally below 33%. . After installing and employ , these turbines produce efficiency less than their nominal amount . The methods no change in structure exist that increase the efficiency or power of the turbine to acceptable level .In this thesis, gas turbine and to improvement performance methods has been studied . gas turbine with the methods are simulated to obtain the effect of each method in different environmental conditions . Economic sensitivity analysis... 

In this project, multi objective optimization (MOO) approach is used to optimize the SOFC/MGT integrated system performance in two strategies. In order to improve the performance and increase of Micro Gas Turbine (MGT) efficiency, it can be combined with Solid Oxide Fuel Cell (SOFC) which it has high operating temperature.The multi-objective optimisation method used allows to generate Pareto curves that represent the trade-off between conflicting thermo-economic objectives of SOFC/MGT integrated system, like, electrical efficiency, output power and electricity cost. The results of the thermo-economic optimization offer a basis for decision making and engineering improvement. SOFC capacity... 

The present study was aimed at developing a model to optimize the sizing of wind turbines according to the region’s wind condition and the capital costs of each part of the turbine. The proposed model, which consists of technical aerodynamic, economic and optimization sub-models, is used to achieve maximum annual energy production by a fixed cost of a single or a number of wind turbines. A cost model has been used to determine the detailed cost of the turbine’s components. The model’s results are presented for two regions in Iran, Khaf and Ahar, and the optimized configurations for a single turbine and a wind farm have been investigated.A case study for the region- Manjil that has some... 

Inappropriate effects of fossil fuels and conventional power generation systems on the environment have necessitated a sustainable energy system for the next decade by growing interests in renewable energy systems. The world’s most fast-growing renewable energy resource is the wind energy. The main problem of wind power is the power fluctuations at the load side caused by the variable nature of wind speed, and the main issue in case of remote locations is the long-term storage of power generated by wind turbines. Batteries can be used to store a limited amount of energy for a short time. Although new advances in this field have been achieved, most common type of batteries is hardly able to... 

Low effiencies of equipments and lack of forecasting heat integration in some oil regions are the reasons of primary energy losses in these regions. Also there have been difficulties in providing electric power demands in regions separate from the state electricity network which is a barrier in front of exploiting all the potentials of the region. This research introduces a model that can lead to selection of optimal configuration of equipments and units in order to establish a CCHP system that answers variable electric, heating and cooling demands ensuring a safe margin of power generation. The model simultaneously has the ability to select between existing and new installable equipments.... 

As a matter of fact, power systems are always faced with a variety of uncertainties. These uncertainties change system parameters in an unwanted manner which may deteriorate the system security and reliability. For instance, a transmission line which is designed for a certain capacity may be suffered as a result of load increment and consequently may influence the normal operation of other network elements. In recent years, as a result of environmental considerations and especially after the oil shock at 1973 which caused the the energy prices to increase unprecedentedly, the human has taken more attention to renewable energies exploitation. Theses energies have a fluctuating nature and are... 

World environmental concerns sharp increase in necessity of using energy in comparison with permanent progress in the field of renewal energy technologies causes modern forms of energy sources which can be used by public. This project studies the increasing influence of the wind power in power systems and also designing and exploiting techniques of local saving energy systems. For this purpose, models and possibilities in order to anticipate the operation of wind farm which is connected to grid by saving energy is described. In this project, the operation of compound system components which is totally a combination of three systems is being studied. The considered compound systems consist of... 

Nowadays, the use of gas turbines with low capacity have acceptance in large quantity. This type of gas turbines with a capacity of approximately 5-200kW are known as microturbines. This type of turbines due to the existence of limitations on increasing of turbine inlet temperature and compressor pressure ratio has low efficiency compared to the turbine with high capacity. Therefore the use of a recuperator in the cycle is necessary. Optimum design of heat recuperator has important effect on improving of gas turbine cycle efficiency. In this project for optimum design of heat recuperator, the effect of recuperator on gas turbine cycle efficiency is studied. By determining geometric... 

It has been well documented over the years that axial and radial inflow turbines have traditionally been the solutions of choice for organic Rankine cycles. Recently, the advantages of radial outflow turbines in various operating conditions of the organic Rankine cycle have been highlighted. However, no research has been done on the use of this type of turbine in other cycles and for relatively high cycle pressure and temperature conditions. Further, there is no information on the design process of radial outflow turbines in the open literature. The purpose of this research is to compile a relatively accurate process of designing a radial outflow turbine and the feasibility of using it in a... 

This research investigates the use of baffles in sector jets for film cooling of turbine blades. The goal of this study is to compare the cooling performance in three conditions: sector jet without baffles (one 90-degree arc), with one baffle (two 45-degree arcs), and with two baffles (three 30-degree arcs). The effect of using this type of cooling is also compared to the crossflow jet, which is the simplest type of cooling jet. In all conditions, the mass flow ratio is constant and equal to 1. The problem is solved for a turbine blade with the “AGTB-B1” airfoil. The problem is first solved with the Transition SST turbulence model, and the results are used as the initial conditions for the... 

The limitations of metals in tolerating thermal stresses is one of the main obstacles in increasing temperature of combustion products. In addition, strong desires to use higher temperatures than are allowed for metals, have led to use of different cooling methods for protecting surfaces adjacent to hot gases. Previous valid studies show that more than 25% of research in the field of gas turbine is related to their blades cooling. On the other hand, one of the very important methods of cooling such surfaces is film cooling. The results of this and previous researches conducted by the team of this thesis’ supervisors can for instance help designers to predict more suitable positions for... 

Increasing the surge margin of compressors and preventing surge and stall phenomena have always been one of the main concerns of gas turbine engines. This research aims to numerically investigate the fluid injection effects on the surge margin in centrifugal compressors. In this regard, the NASA CC3 compressor is selected for validation purposes. Considering the available geometrical data, a simulation is performed by using Ansys software, and results are compared with those available from public literature.After the performance and accuracy of the fluid injection simulation results are validated, fluid injection is implemented in the newly selected location and its impact on the compressor... 

One way to increase the power and efficiency of the gas turbines is to cool their incoming air. There are different methods to cool down the inlet air. One of the most widely used and suitable method is spraying or fogging the water droplets into the air at the gas turbine air inlet. In this research and for the first time, the effect of fogging system on the performance of a combined cycle incorporated with a J-class gas turbine (M-501J) is investigated using the computational fluid dynamics (CFD). There are so many parameters, which affect the amount of achieved efficiency. A few of them includes the average temperature and humidity at the outlet, the evaporation efficiency of the water... 

This project has been carried out to investigate the feasibility of using thermoplastic materials in constructing large wind turbine blades made of composite materials. By proving the similarity of the mechanical behavior of blades made of thermoplastic and thermosetting composite materials, the possibility of using these materials with better recycling capabilities has been studied. By studying different thermosetting and thermoplastic resins and checking the Processing methods and mechanical properties of thermoplastic resins, the materials for blades have been selected. The suitable manufacturing method for producing large blades with dimensions above 30 meters is the vacuum-assisted...