In this research a suitable system is designed and proposed for Mirza K.Khan factory. In existing system which is using by factory, the one-time path water is being employed to produce vacuum in condensers which consumpt huge amount of water. But in proposed system through considering effective parameters, a hybrid cooling tower aim to reduction of water and energy consumption was designed. Since the hybrid cooling tower is composed of wet and dry cooling towers, the most of related equations are same as equations which are relating to wet cooling tower and air cooled heat exchanger. So for realizing the behavior of flows and processes an induced fan counter flow wet cooling tower and an air cooled finned heat exchanger are numerically modeled. The results of air cooled heat exchanger modeling are validates with Aspen B-Jac software. The ratio of water mass flow by air mass flow is one of the major and important parameter in wet cooling tower designing and also many designing parameters including flow and fan dimension depend on this parameter. Through drawing of IM curve-thermal characteristics of the tower-and IP curve-cooling core characteristics- regarding to flow ratio, the collision point of these curves which defines desired design flow ratios founded. The water consumption rates of wet cooling tower and hybrid cooling tower with PPWD and SPWD configuration regarding to different ambient dry bulb temperatures for one working season – including last five month of year- are compared. Finally among three described towers, hybrid cooling tower with PPWD configuration due to least water consumption is selected.

Electrical energy storage is very expensive and there are no procedures for this work. Methods available or economical or do efficiency not very good. Pumped storage power plant way in the past few decades has been received researchers and operators. Pumped storage power plants, hydroelectric plants are types of of engine performance during low load hours electricity network on the one hand and the production of electricity at peak system load on the other hand, can play an important role in improving the performance of the system of production. In Iran, due to drought and lack of atmospheric precipitation in recent years, Pump storage method, the method is suitable and affordable. In this study is to identify the criteria for initial troubleshooting option for pumped storage power plants using criteria: a) Ideal site: topography, meteorological, hydrological, flooding, sedimentation, seismic and reservoir, the plant has been studied of the Siahbishe and Masjed Soleiman. b) Installed capacity: parameters can be in installed capacity pumping head height, the pump and turbine noted. To make primary powerhouse parameters as well as parameters to optimize installed capacity, according to mathematical modeling and methods of decision variables, objective function and constraints or related conditions identified and formulated, then, using software optimization (simplex algorithm, genetic), we aim to function optimally. In this study by comparing the location of of the Siahbishe and Masjed Soleiman Power Plant has concluded that turned pumped storage power plant. On the other hand, also improved by optimizing the values to be useful to power turbines and pumping of the Siahbishe achieved, read also be useful in optimal amounts of useful power turbines and pumping in pumped storage power plant was to become Masjed Soleiman power status. Both simplex and genetic optimization algorithm, and the two methods were compared with each other. In this comparison it was concluded that the simplex algorithm for linear modeling to genetics is faster, but less precise.

 

The process of separating suspended particles from liquid phase by gravity is referred to as sedimentation. In this research, sedimentation reservoir of Khouzestan Oxin Steel Company is investigated in full scale mode and with totally real data. Required information like particles diameter, particles aggregation and particles mass flow are obtained by doing the necessary tests such as PSA and SEM tests on samples. The settling tank is simulated by Ansys Fluent software. At first the pure water is simulated in 3-D, turbulent and steady form in the absence of particles. Then particles are injected into flow field and tracked by means of discrete phase model. By comparing the results of the simulation with experimental results, it is proved that the results of the simulation with SST K-ω model have a better agreement with experimental results compared to the Standard k-ε model. Three suggestions are presented to improve the performance of the settling tank: 1-Adding a baffle that is mounted in the floor and extends to near the free surface 2- Adding a baffle that is mounted in the free surface and extends to near the floor3-Installation a two-sided baffle that is mounted in the free surface and extends to near the floor. The settling efficiency decreases from 39.3349 to 38.1555 percent in the first state, it increases from 39.3349 to 62.95045 percent in the second case and it increases from 39.3349 to 51.6124 percent for third case. These three suggestions are checked by short circuiting phenomena condition and introducing the concept of successful settlement theory. The successful settlement theory states that a particle can be accounted as settled particle just when it stays static and stable in the floor of tank and also it doesn’t return to sewage again. Accordingly, although second proposal creates more efficiency but third suggestion is selected as the most appropriate method in order to settling tank optimization. The reason for this choice is that unlike second suggestion, the third proposal satisfies the necessary conditions for successful settlement theory and short circuiting phenomena too.

 In this research, Alstom hydrogenerator rotor fan of Karoon 4 Dam is studied numerically, in order to improve the flow of cooling air in generator zone.Geometric modeling, mesh generation and flow solution in the computational zone inside the rotor fan are included in numerical analysis of the fluid flow.Geometric modeling is done using computer-aided design software. Afterwards, mentioned geometric model has been transferred to the mesh generation software.The structured computational mesh has been created inside the rotor fan complicated computational zone. By determining the boundary conditions and the rotating reference frame, the flow was studied to find out the solution.For simulating the turbulent flow inside the rotor fan, the realizabe (k-ε) model is used. Comparing numerical and experimental results, revealed 10.8% difference.Results of flow solution are shown as pressure, velocity and temperature distributions and Stream lines in different sections of the rotor fan.Considering simulation results, rotor fan geometry has been optimized in a way that makes no changes in its overall structure.By modifying the rotor fan inlet geometry and inserting blades at its inlet in order to eliminate inlet vortexes, the flow rate has been increased up to 18.62%.

 The simulation of the two-phase flow of the lower bearing of the generator of Shahid Abbaspour Power Plant in the city of Masjed Soleyman, Khuzestan province, was carried out in this research. The flow of problem is steady and laminar. The intended geometry consists of three general parts of the lower bearing, an oil tank with fitting L shape blades installed on the body on it and a steel shaft. The shaft and the oil tank are circulating at a special speed. At first, the solid model of these parts with the area around the blade was created according to the existing plans of Shahid Abbaspour Power Plant by Salidworks software. After it, the volume of fluid passing through solid parts was pulled out and was modeled as the computational domain of this research. So the three dimensional model was meshed with Gambit software and the appropriate boundary conditions for the problem was selected and analysed by VOF method in Fluent software. The variables of velocity, pressure and temperature were investigated in different points of the system. The results showed that the blades installed on the body of the tank play a significant role in cooling of the set and the heated oil. Whatever the oil film builds faster, the performance of the set is improved. At the earliest times of rotating of the system, the oil is created on the oil film with more speed and when the oil reaches the outlet pipes, the filling of upper parts is done slowly. To improve the cooling operation, two methods were proposed. The first method is to change the dimensions of the blade in two directions, longitudinal and transverse, and the second method is to increase the volume of oil in the rotating tank. The results showed that the pressure changes reached to the maximum value near the grooves and the highest temperature in the system is related to the very thin oil film. The most changes in the pathlines occur in the hot zones of the bearing because this part of geometry is the core of the system and most pipes are connected to this area. The results were compared with the existing data of the power plant and a good match between the results observed.

The ground temperature, in the summer, is lower than the ambient temperature; as a result, the ground can be employed as a natural heat sink. In other words, the air is circulated by the earth tubes which are buried in the ground. The surrounding cool air is then transferred and the interior space, which is supposed to be an industrial space, is air-conditioned. Regarding the required cooling load of the industrial space, the earth tubes are laid in parallel lines with an appropriate distance from each other. In this work, a D model of the cooling ground exchanger is designed in the Gambit software. This model is then analyzed for a full day of Tehran’s climate using the Fluent software. The system is supposed to air-condition an industrial space. The diffusion of the heat in the surrounding soil of the earth tube and also the effects of the soil thermal saturation on the cooling potential of these exchangers are considered for more accurate results. By determining the cooling load generated in an earth tube and investigating the effects of the geometric parameters, soil thermal characteristics, and the air flow rate on the heat exchanger’s performance, it is found that reduction of the tube’s diameter, reducing the inlet air velocity of the exchanger, and increasing the exchanger’s length can improve the system’s cooling potential. In addition, burying depth of more than m has negligible effects on the exchanger’s outlet temperature. It is also observed that the maximum soil thermal saturation occurs at the entrance lengths of the earth tubes as the duration of hours elapses. Lastly, it is found that providing comfortable thermal conditions of an industrial space using the cooling ground heat exchanger is only applicable for large numbers of earth tubes because of the considerable cooling load of the industrial space.

The purpose of this research is design and analysis of hybrid propulsion systems to using in an operational Unmanned Aerial Vehicle (UAV) and discovering applicative aerodynamic design with that. Therefore the project has been done in three steps of designing and building of hybrid propulsion systems, designing UAV body and at the last, UAV stability analyzing. With selection of desirable propulsion system and check type of devices arrangement and emplacement, The device is designed to simulate the hybrid propulsion system and at three electric, Fuel and hybrid mode, UAV endurance is examined. Experiment results and numerical analysis shown that the endurance improved in hybrid mode with respect to electric mode by 17 percent and to fuel mode by 8 percent. Then, according to the propulsion system emplacement, UAV aerodynamic design is done. Based on the geometric shape design, the weight of different parts of the bird, the aerodynamic center location and the gravity center location is specified by the Catia software. Then UAV aerodynamic coefficients is calculated by the Digital Datcom software in this gravity center location and by the output data of this software, longitudinal dynamic stability of UAV is examined. The results of this study and experimental test show that the UAV has a convergent semi-swinging stability at the center of gravity of 40 percent and 4° angle of attack, also if the bird weight reduces to the range of below 4.5 kg, the UAV will has a non-swinging stability.

Nowadays the importance of air-conditioning is not covered for anybody. For air-conditioning in hot and humid regions such as Persian Gulf countries, using mechanical vapor compression devices (MVC) is the most common method. These devices have two main drawbacks: First, they consume high rates of electrical energy and second that, they are environmental pollutant and harmful to ozone layer, because of using chlorofluorocarbons (CFCs) as refrigerant. For such reasons many researchers are looking for alternative ways for MVC method. One alternative method is evaporative cooling. Because of the direct contact of air and water streams in evaporative cooling mechanism (which usually happens on an external solid bed), a small amount of water evaporates and the temperature of water and air streams decreases simultaneously. It's worth mentioning that evaporation (which is a reducing factor of tempereture) is highly dependent on relative humidity of air stream. considering this, in the case of humid air stream, no significant temperature drop occurs. Therefore, this cooling method is not efficient in conditions with high relative humidity. To resolve this problem in Direct Evaporative Coolers (DEC), some parts such as air pre-cooler and cooling tower can be added to reduce the temperature of output air. In this study, by adding these sections on a DEC and carrying out the cooling process in two stages, its performance is experimentally measured and compared to a DEC. Innovation used in this research is the separation of direct evaporative cooling section water loop from air pre-cooler water loop. As the result, DEC section water temperature can reach to the pre-cooled air wet-bulb temperature, which is lower than the ambient air wet-bulb temperature and the cooling tower outlet water temperature. Results indicate that the efficieny of DEC in normal operating conditions, ranges from 55 to 72% with an average of 65%. While the average efficiency of new design Two Stage Evaporative Cooler (TSEC) in the same condition is about 115%. The TSEC in almost all hours of operation was above 100% and have been recorded up to 120% in some hours. this means that the outlet temperature of the new TSEC design is less than the ambient wet-bulb temperature. A closer examination of the results shows that the efficiency of the TSEC is almost independent of ambient air relative humidity and its wet-bulb temperature.

The performance of dry gas seal is simulated by using Computational Fluid Dynamics. The effect of gas flow state on the seal performance is analyzed under different gas film thickness.The Laminar model and k-ε RNG turbulent model are used separately to obtain the opening force, leakage rate and stiffness film.The geometric model of the problem that includes a rotating ring and a fixed ring, was obtained.The grooves of the rotating ring in order to compress the flow. Therefore, the computational area is gas film between two ring and the film gas into the groove. Then the computational domain transfrerred to generate computational mesh software. For the computational domain have been used structure hexahedron cells. According to the results, it was found for all three geometric model that dry gas seal works in laminar flow. For uni-directional optimized geometric parameters are α=15, ξ=1.25 and γ=0.4 Obtained. where α is the groove angle, ξ is the ratio of groove with to the land with(circumferential) and γ is the ratio of dam length(radial).the effect reverse speed on the performance dry gas seal is analyzed. The results showed that the opening force reduces 8% while rate leakage increases 0.38%. Therefore we use the bi-directional groove. For bi-directional groove the two geometric models is analyzed. The results showed that the first geometric model is better than the second geometric model.

The most important factor of sedimentation in reservoirs of damsis the dense or density currents. In the torrential seasons,te entrance current to the reservoir has high concentration of sediment material because this flow is spread in lake froth, its velocity is reduced and during its movement suspended particles is deposited gradually and in the form of turbidity current is flowed to the dam's body. One of the prevention methods for the deposition of sediments and unloading them from the reservoir is using hydrodynamic force of water.The progressive section or the forehead is the most important and considerable parts in dynamic of the dense currents.The main goal of this research is the understanding the speed of movement and the method of diffusion of the sediment currents. In this study, reservoir is simulated with a physical model. In this case,the main channel which its length is 6 and its width is 1.44 meters by a glass made wall can be separated into two parts the smaller part is for store dense fluid and larger part is for reservoir containing clear water is used.Also these two parts connected to each other with gate slide for density current. With changing the geometry of the reservoir froth and building a channel that it has two type, constant and convergent cross section, at the entrance dense current into clean water tank, which is tried to reduce diffusion of dense current and to increase the flow velocity and therefore reduce deposition of sedimentary particles. Twelve, tests series were used for experiments. Variable parameter in doing experiment included two concentration 3 and 6 g/l, and two flow rate 2 and 3.5 m3/h, and in order to change the geometry of channel froth which is considered three models: without input channel, input channel with constant cross section and input channel with convergent cross section.The results show that, the velocity and height of forehead in during the movement and diffusionare reduced, and with increasing the initial concentration and flow rate, velocity is increased. Also is observed, Whatever the flow rate is lower, creating guiding channel in entrance density current lead to increasing velocity and forehead concentration and effect of constant section channel as compared with convergent section channel, in increasing of velocity and concentration is best.

Turbidity current analysis is important in settling tank clarifiers. In this thesis manner of propagation, velocity and concentration profiles in high concentrated turbid current of a prototype geometry is investigated. In this research, turbid current is simulated using Fluent commercial software. Unsteady simulations are performed in two phase flow. Mixture multi-phase model is used to simulated high concentrated turbid current. High concentrated turbid current is considered as a non-Newtonian fluid which viscosity is related to concentration. In Fluent software, user define function is used for fluid viscosity. The effect of different factors such as entering turbid current velocity, Newtonian and non-Newtonian turbidity current on velocity and concentration profiles were investigated. The simulation results were compared with the experimental ones. The agreement between simulations and experimental data confirms the capability of this method for modeling the turbidity current. The simulation results show that maximum velocity and sedimention height in non Newtonian turbidity current are more than maximum velocity and sedimention height in Newtonian turbidity current and it is because of high concentration in non-Newtonian turbidity current.