جستجوی مقالات مرتبط با کلیدواژه "مزرعه باد" در نشریات گروه "مکانیک"

In the current research, a renewable system based on wind, solar, and geothermal energy was analyzed with a targeted combination of fuel cell units, heat pump, proton exchange membrane electrolyzer, steam turbine and reverse osmosis. Transient modeling and simulation of the proposed system was done using TRNSYS software. This system was designed and evaluated to meet the needs of a residential complex with 80 residential units and 320 people for electrical energy, cooling, and heating. A case study was conducted for the feasibility of setting up the proposed system in the coastal city of Bandar Anzali in Iran. Optimization of system performance was done by determining two objective functions of production power and system life cycle cost with response surface method and Design Expert software. Five parameters affecting the system performance including the number of wind turbines, number of solar panels, fuel cell capacity, steam turbine capacity, and proton exchange membrane electrolyzer capacity were selected as optimization variables. In its most optimal state, the system can reach a production power of 3036105.022 kWh and a life cycle cost of 781944.254 $. The environmental results showed that by setting up the system in an optimal mode in Bandar Anzali city and producing electricity at the rate of 3036.1 MW per year, it is possible to help expand 3 hectares of green space per year. It also helped reduce carbon dioxide emissions by 619.36 tons of CO2 at a cost of 14,864.74 $.

In this paper, first the complete geometry of the Vestas wind turbine has been created, and an unstructured mesh around the blades is produced. Velocity profiles have been extracted by assuming a single wind turbine in the assumed computational area and inlet velocity of 6.7 m/s, and it was found that the maximum reduction in velocity has occurred at the nacelle height approximately. Also, velocity recovery at a distance of 2 to 6 times of rotor’s diameter (2D to 6D) is far greater than the distance of 10 to 20 times of the rotor’s diameter (10D to 20D). The velocity reduction has been recovered in 10D downstream of a wind turbine up to 50% and still exists in 20D downstream. It was shown that the wake effect occurs at a maximum distance of 1D besides the turbine. According to the results, the efficiency of the wind farm is 62.0263% if the distance between the turbines is 5D and the input speed to the computational area is 10 m/s. The calculated velocity profile and efficiency obtained from the assumed wind farm come to the conclusion that the optimal distance for placement of wind turbines is 5D downstream and 1.5D lateral.

Nowadays, with regard to the reduction of fossil fuels and the management of their use, wind power is now rising as one of the most efficient renewable energy sources. Moreover, wind farms, which include sets of turbines in a vast farm, have become more developed and their designs and optimizations have risen recently. In this paper, the wind turbines are located in the wind farm and the effects of their positions and arrangements on the production power of the whole system are investigated. For this purpose, a square farm is considered and, having information on how the winds and wind speeds in each case (based on the Weibull distribution function), will extract the optimum location of wind turbines in the farm using optimization algorithms. The main goal of this research is to increase the total amount of power extracted from the wind farm based on the changes in the locations and arrangements of the turbines. This optimization problem is subjected to some constraints, such as the maximum number of turbines in the farm, the minimum distance between turbines and the overall size of the farm. To solve this optimization problem, the GA and PSO algorithms are used and the results of these methods are compared. The results of this study indicate that the power produced from all the turbines located in the wind farm has increased compared to previous works.

With the recognition of wind energy in the world, wind farms are expected to become more extended and cover increasingly larger surface areas. The most important issue in large wind farms is increasing power and efficiency. When wind turbines are deployed in large arrays, their efficiency decreases due to complex interactions among themselves and with the atmospheric boundary layer (ABL). When the length of the wind farms exceeds the height of the ABL by over an order of magnitude, a “fully developed” flow regime can be established. Since the length of the farm is larger than the atmospheric boundary layer thickness, changes in the streamwise direction can be neglected and the relevant exchanges occur in the vertical direction. In the wind farms established in the fully developed atmospheric boundary layer, the kinetic energy extracted by the wind turbines is transported into the wind-turbine region by vertical fluxes associated with turbulence. Surface roughness is one of the most important factors affecting this phenomenon. In this research, the effect of surface roughness on the efficiency of the large wind farm in the ABL by large eddy simulation is investigated. For this purpose, the large eddy simulation (LES) is applied to solve the turbulence flow equations. In this article wind turbines are modeled using the classical drag disk. The various surface roughnesses are modeled by logarithmic wall functions applied to the bottom of the domain. The results show that the efficiency and power of the wind farm are decreased by increase of surface roughness.

Wind power is an important parameter for estimating the potential of a wind farm; it is used to compare different sites. In this study, wind power estimation under four different regions of Iran was investigated. For this purpose, the wind data of the Mayan, Bardsir, Morche Khort and Khash have been recorded at a time interval of 10 minutes per year. The algebraic and graphical methods were used to estimate the constants of the Weibull function, which were used to determine the wind power in the selected regions. The Weibull function used in this study is a twovariable function. After determining the Weibull constants, the wind power was determined. Six types of turbines with different powers and heights were used to estimate the power output. The results showed that in the selected cities, using wind turbines with variable power, which were required low wind speeds to start, could be producing electricity. The Mayan station is the most desirable space to install the wind farm.

In this paper, the axisymmetric actuator disk method (2D) with acceptable accuracy and low computational cost based on computational fluid dynamics have been adopted to study the flow behavior around the horizontal wind turbine rotor and the wake. For this sake, a C code is developed as a self-developed user-defined function (UDF) in commercial software package ANSYS FLUENT. The rotor is modeled as a virtual disc and its effect is added to the Navier-Stokes equations as a sink term. The results obtained for the 5 MW NREL wind turbine in this study show the appropriate accuracy and speed-up. The interaction of two wind turbines in the wind farm has been investigated. The results depict that the output power and thrust of the downstream rotor due to the presence of an upstream turbine drop up to 88% and 57%, respectively. Also, radial distribution of the downstream rotor power shows that at a closer distance, the middle part of the blade has a larger contribution to power generation. Further, the effect of downstream rotor on the upstream rotor performance is up to 1.5% and 0.7% reduction in power and thrust respectively.

The increasing use of the photovoltaiv sources and their low efficiency, makes it very important to study on different ways of anhancing their efficiency. In this paper, after designing a photovoltaic farm, the heat transfer equations in solar cells are investigated. Considering the effect of the wind speed on these equations, a solution is provided to decrease the temperature and then increase the efficiency of the photovoltaic panels. Therefore, by means of the meteorological data and three softwares (System advisor model, Matlab and Meteonorm), the 1 MW photovoltaic farm in climate condition of Yazd province is simulated. Then, the effect of wind speed on the efficiency of the photovoltaic farm is investigated. Results shows that with the increase of the wind speed up to 17 m/s, the output power of the farm is considerably increased. For the wind speed upper than 17 m/s, the output power increase is negligible.

Research on atmospheric boundary layers in wind farms is an important task. Especially, wind effect on wind turbines installed in mountainous area with complex terrain is complicated. In this research, the wake of a wind turbine and wind flow in complex terrain have studied with computational fluid dynamic (CFD) method in OpenFOAM software. Actuator-disk model with introducing forces, based on Blade Element Momentum Theory, on the disk are used. For simulation of wind turbine in wind farm, Reynolds averaged Navier Stokes equation with k-ɛ turbulence model has been used. Structured mesh was used for simulation domain. Also, main wind direction has been determined from North toward south considering wind rose of area. One of wind turbines is studied by detail. The numerical results show an extended wake effect around 5d (five times the rotor diameter). Wind speed deficit is 26% at this distance. Captured wind power from the simulation is close to real data. Also, wind regime has been studied and analyzed for different seasons. For November, December and January, the time period that wind blows in effective speed, is decreased less than %50 which is important in wind farm design and operation.