Sharif Digital Repository

In the earthquake conditions, the collapse of cooling towers can stop power station activities and heavy financial losses that can be led increasing disaster dimentions finally. In this thesis for analysis of concrete hyperbolic cooling towers and generally for analysis of shell structures, the endurance time (ET) method benefits are used. Also with comparision between ET and standard time history method (THA), accuracy and probable errors of ET method are discussed. It should be noted that ET method is a new time history based method of seismic analysis expect that in this method, structure is imposed under specific intensifying acceleration functions. ET method is capabable for nonlinear... 

The huge jam complex unit in assaluye (tenth olefin plan) with the capacity of 1320000 tons of ethylene and 306 thousand tons of propylene is considered as one of the biggest olefin units of all world. It is found that the bottleneck of increasing the capacity is the demethanizer unit. In this thesis, after simulation of the demethanizer towers, capacity enhancement is accomplished along with comparing the outlet stream with PFD data in terms of mass fractions, temperature and pressure. in addition, the hydrolic treat ment of towers is checked. This is continued till a problem occures in each of towers. In the bottleneck capacity , a solution and some changes have been offered. Thereafter... 

In this paper, carbon structures such as multi wall carbon nano tubes, graphene and hybrid graphene-iron oxide, for utilisation in wet cooling towers in order to improve heat transfer are being discussed. All synthesized nanoparticles are prepared by chemical vapour deposition and wet chemical methods. Nature and structure of the created particles is also being examined by using X-Ray diffraction, transmission electron microscope and scanning electron microscope. The water used in this research is a kind of brine water, currently being used in industrial cooling towers at oil-rich regions of southern Iran. Performing the ICP test on the available water and by exact determination of its... 

Electrical power is an inseparable part of human life. Therefore, design and analysis of electrical transmission towers have always been important for scientists. In common design methods due to the lightness of these structures only the wind load is considered and earthquake effects are neglected. On the other hand, regarding regulation No.2800 a lot of areas of Iran are located in earthquake zones. Therefore, it is necessary to evaluate the performance of these structures against earthquakes. In this research, regarding conducted studies, we decided to use incremental dynamic analysis method (IDA) in order to evaluate seismic performance of the tower. In sake of thoroughness of the... 

In this research, a multigeneration system was designed and evaluated, utilizing solar and geothermal energy to generate electricity, fresh water, hydrogen, and oxygen. The system's performance was assessed from energy, exergy, and economic perspectives. The setup involves a solar tower contributing energy to the gas cycle and a geothermal well supplying preheated water for the steam cycle. The system employs a molten salt cycle to capture heat from the solar receiver, transferring it to the air cycle. The remaining energy requirement is met by the Air Brayton cycle, which combines methane and hydrogen as fuels within the combustion chamber. Additionally, a steam cycle is integrated to... 

The utilization of tower cranes at construction sites presents numerous inherent risks. These cranes are commonly employed for lifting heavy loads, which carry the potential hazard of accidental falls. Simultaneously, workers may inadvertently overlook overhead dangers while focusing on their tasks. To mitigate these risks, laws in many countries explicitly prohibit individuals from occupying the vicinity directly beneath suspended loads, known as the fall zone. Such measures are vital to safeguard against the peril of heavy loads plummeting onto people. However, existing studies have not offered a comprehensive and efficient approach to identify crane load fall zone. To address this gap,... 

Airport Traffic Control Towers (ATCTs) are among the most critical structures in an airport that are expected to keep their level of serviceability after severe strong earthquakes. Therefore analysis and design of these structures need a detailed investigation on the seismic behavior of the structure based on the structural characteristics. In this study three different existing reinforced concrete ATCTs have been investigated. As important parameters of earthquake design of structures, response modification factor (R-factor) of these towers will be determined. R-factor reduces elastic force level to design force level and contains the effect of ductility, overstrength. In Iranian seismic... 

The enviromental wind would cause serious drop in the performance of Heller cooling systems in thermal powerplants working on Rankin cycle. Therfore, it is necessary to consider the wind velocity in the design of such cooling tower systems. We use the computational fluid dynamics (CFD) and simulate the 3D buoyant flow passing through and over a heel cooling tower. We consider three different wind veocities of 0, 5 and 10 m/s in our simulations. In order to consider the low efficiency of the cooling system in efficiency drop of the main rankin cycle, we need to consider actual power generated by the powerplant generator, which is directly affected by the turbine back pressure. To connect the... 

In a solar central system plant about 40% of energy losses occurs in the heliostat field. Furtheremore, half of the investment costs for construction of the plant is related to the heliostat field. Therefore, an optimal design of the heliostat field is necessary for reduction of levelized cost of energy in solar tower power plants. In this study, in order to optimally design the heliostat field, first energy performance of the helistat field in one year is simulated. Solar power and sun’s position at each moment of the day is determined by mathematical relations. Then, loss factors in the field are modelled and heliostat field layout is designed by an algorithm. Finally, by using PSO... 

Elevated tanks are typically used to store water for drinking as well as fire fighting purposes. The failure of these critical structures during earthquakes can potentially lead to shortage of drinking water, difficulty in putting out fires, and substantial economical losses. Due to the fact that a large number of water tanks with insufficient seismic resistance were extremely damaged or collapsed during past earthquakes, (e.g. the elevated tank of Rasht in 1989 Gilan's earthquake), the reliability of these structures against failure under seismic loads is of critical concern. Numerous studies have analyzed and investigated the dynamic behavior of fluid storage tanks; however, most of them...