Tower Diameter Research Articles

Novel strengthening method of signal tower using prestressed CFRP plates: Concept and behavior

A novel prestressed carbon fiber reinforced polymer (CFRP) plate strengthening method for signal towers was proposed. The proposed strengthening system incorporates a circumferential anchorage system, a support system, a column system, and CFRP plates. These elements synergistically interact with the tower, forming a self-balancing system. This integrated system can provide exceptional flexural capacity and reduce the lateral displacement of the tower under wind load. To validate this novel method, a series of four static load tests were conducted. The results showed that the initial stiffness of the strengthened tower with CFRP plate prestresses of 0, 200, and 400 MPa increased by 71.0 %, 113.8 %, and 113.8 % compared with the unstrengthened tower, respectively. Moreover, the CFRP plate slacking occurred later for the strengthened tower with higher CFRP plate prestress, and the stiffness of the tower after the CFRP plate slacking kept increasing as CFRP plate prestress increases. The results indicate that the prestressed CFRP plate strengthening method effectively improved the behavior of the tower under wind load. Moreover, the finite element method (FEM) was utilized to analyze the influence of the ratio of the circumferential anchorage system height to tower height, the ratio of the support system height to tower height, the ratio of the column height to tower height, the ratio of steel support length to tower diameter, the elastic modulus of the CFRP plate and CFRP plate prestress on the strengthening effect. Finally, a strengthening procedure was proposed according to FEM results and sensitivity analysis. The analysis findings can serve as a guide for designing the strengthening system.

EFFICIENCY DETERMINATION OF SOLAR CHIMNEY POWER PLANT RETROFITTED WITH NOVEL FINNED COLLECTOR UNDER REAL-TIME SOLAR IRRADIANCE

This paper discusses the three-dimensional numerical study of a new finned collector integrated into the solar chimney power plant. Manzanares pilot's details, which are tower height 194.6 m, rooftop height 1.85 m, rooftop diameter 244 m, tower diameter 10.16 m, and pilot mean temperature 20°C with air speed 15 m/s, are implemented in this work to check the suitability of the finned collector as a way of improvement. In order to assess the unique idea, a parametric study is done with different number of fins: 46, 33, and 25; different fin widths: 0.5, 0.25, and 0.1 m, and different fin heights: 1.2, 0.925, and 0.6 m. Therefore, optimal outputs could be obtained by the novel rooftop that is proposed in this study, where the efficient case is specified dimensionally by 46 fins, a fin width of 0.1 m, and a fin height of 1.2 m, which gives 1.674% as the station performance, 700.597 kW as the resulted power of the plant, 1790.3 as the Nusselt number, and 1.96E+14 as the Rayleigh number.

The Effect of Wind Direction on the Cooling Capacity of Short Dry Natural Draft Cooling Towers Operating in Close Proximity

Abstract The layout of multiple natural draft dry cooling towers could have a significant influence on the performance of the cooling system in concentrated solar power (CSP) plants; however, this has never been quantified. Hence, this work used computational fluid dynamics (CFD) modeling to analyze the cooling capacity of two short natural draft dry cooling towers (NDDCTs) on a common site for a range of tower spacings, wind-speeds, and wind incidence angles. The results show that the cooling performance of the towers is a strong function of tower spacing and their orientation with respect to the wind direction. It was found that when the wind came at a 90-deg wind incidence angle (i.e., normal to a line drawn between the two towers), their cooling capacity was improved at tower spacings of less than 1.8 tower diameters (1.8D), though for the other tower spacings, there was no interaction between the towers. However, with the wind at 45 deg to the towers, the flow around the towers resulted in a decrease in their cooling capacity at tower spacings of 1.8D and 2.6D. Most interestingly, it was found that orienting the towers in line with the prevailing wind direction delivered improvements in the cooling capacity of up to 30%. This is due to the windward tower acting as a passive windbreak. Hence, as CSP plant capacity is increased, and additional cooling towers are required, these should be placed close to any existing tower and oriented along the line of the prevailing winds.

Dynamic analysis on monopile supported offshore wind turbine under wave and wind load

Monopile offshore wind turbine (OWT) accounts for more than 65% of all OWT types. Monopile OWT is a soil-pile-tower system and can be divided into three stages: the stage embedded in the soil, the stage submerged in the seawater and the stage exposed to the air. Based on the improved Tajimi formulation and dynamic principle, this paper establishes a three-stage monopile OWT model to predict the dynamic response of the structure. The displacement of the tower under different wind velocities is obtained. The solution is compared with the Finite Element Method (FEM) result to verify its correctness. The influences of different parameters on the structure are discussed. The results indicate that the structure natural frequency is sensitive to the tower length and nacelle-rotor mass. The increasing seawater depth due to scour effect can significantly decrease the foundation stiffness. The influence of axial force and wave load on the foundation stiffness is also investigated. The tower diameter and tower wall thickness are found of vital importance to the tower displacement.

Study of Organic Acid Pollutant Removal Efficient in Treatment of Industrial Wastewater with HDH Process Using ASPEN Modelling

Due to low efficiency and the material choice limitations of traditional evaporation systems to treat acid wastewater, humidification and dehumidification (HDH) as the core process was applied in the treatment and reduction of wastewater with organic acid pollutant concentrations. The forecasting of pH changes and COD reduction is important for the system’s design. Therefore, a study of the pollutant removal efficiency with different parameters, such as the reaction temperature, air quantity, and flow rate was conducted with ASPEN modeling. In this article, ASPEN modeling was used to simulate the water and acid material transformation in HDH system. The process was composed of blocks, such as RadFrac, heater and split. The analysis was taken with different air quantities, tower diameters, heat loads and flow rates. The analysis indicated that the pH of the maleic acid wastewater changed from 3.0 to 5.7. The relationship between inlet quantity, air quantity, inlet heat and the clean water yield was also shown in the modeling results. Based on these studies, we determined that the model can help engineers solve the key problems of HDH systems, such as heat balance calculation, equipment selection, and the prediction of incoming and outgoing evaporation materials.

A combined potential flow–BEM model to study the tower shadow effect in wind turbines

This paper aims to improve the understanding of the wind turbine tower shadow effect by developing a model that combines potential flow and blade-element momentum theory. The change in the flow field due to the presence of the tower is discussed in detail, together with the resulting variations in the aerodynamic forces acting on the rotating blades, as well as the effect on the output power and the blade root bending moment. The tower shadow effect is not only due to the change in wind speed but also to the change in angle of attack. A one-dimensional description of the flow field is therefore bound to be inadequate. The impact of the tower diameter and blade-tower clearance on the rotor power and blade root bending moment can be expressed as a quadratic function of a non-dimensional parameter. Apart from a mild Reynolds-number effect, the results presented are independent of turbine size.

Effect of a Support Tower on the Performance and Wake of a Tidal Current Turbine

Tidal energy is one of the major sources of renewable energy. To accelerate the development of tidal energy, improved designs of Tidal Current Turbine (TCT) are necessary. The effect of tower on performance and wake of TCT is investigated using Computational Fluid Dynamics (CFD) simulations. Transient analysis with transient rotor stator frame change model and shear stress transport turbulence model are utilized in ANSYS CFX. An experimentally validated numerical model with full scale tidal turbine with a blockage ratio of 14.27% and Tip Speed Ratio (TSR) 4.87 is used to simulate the effect of different tower diameters on performance and wake. The effect of different tower diameters is quantified in terms of coefficient of performance (CP). Coefficient of performance for a 3.5 m tower diameter is 0.472 which is followed by 3, 2.5 and 2 m with coefficients of performance of 0.476, 0.478 and 0.476 respectively. Similarly, the coefficient of thrust (CT) on the rotor for 3.5 m tower diameter is 0.902, for 3 m diameter 0.906 and for 2.5 and 2 m diameters are 0.908 and 0.906 respectively.

Experimental Investigation of the Effect of Collector Profile, Tower Diameter and Tower Height on the Performance of Small-Scale Solar Updraft Power Generator

The performance of a small-scale solar updraft power generator is experimentally investigated under the effects of collector profile, tower diameter and tower height. The updraft velocity and temperature are measured from a total of 36 experiment cases. The current study’s objective is investigating the optimum configuration that produces maximum updraft velocity and mechanical power output. The highest average updraft velocity of 1.22 m/s was recorded in experiment case number A-20. The highest average mechanical power of 12.35 mW is produced by experiment case number A-24. Both the collector height and tower diameter have optimum ranges that result in maximum updraft velocity and mechanical power. Increasing the collector height is bounded by heat losses in the collector and lowering the collector height is limited by the friction force where the airflow entrance is restricted. Having a larger tower diameter could have a negative effect on system performance. This situation was observed in experiment case number A-11 where increasing the tower diameter leads to a reduction of both updraft velocity and mechanical power. Since increasing the tower height always results in increased mechanical power, the collector height must be carefully matched with the tower diameter for a given tower height.

Impact of tower spacing on the performance of multiple short natural draft dry cooling towers for calm conditions

Natural draft dry cooling towers (NDDCTs) serve a fundamental role in the deployment of concentrating solar power (CSP) plants. In a multi-tower cooling system, there is a need to be able to position them correctly so that their performance as a group is maximised. To do this, an understanding of the effect they have on one another is needed. Hence, this work investigated the effect of tower spacing on the performance of multiple cooling towers under calm conditions using computational fluid dynamics (CFD) simulations. The applied CFD methods were validated by comparing the current results with real cooling tower results. It found that towers in close proximity would compete for air at their inlet, resulting in distorted velocity and temperature distributions at the radiator surface. Furthermore, the results show that at a tower spacing of less than two tower diameters (2 D) where D is the diameter of the tower, a reduction in the scavenging area between the towers limits the air supply to the towers and this interaction decreases the cooling performance of the towers. The results of three NDDCTs showed that the heat rejection of the middle tower which is surrounded by two towers is highly influenced by the tower spacing and at very low tower spacings, the heat rejection decreases by up to 15%. This new finding holds particular design significance if multiple NDDCTs are deployed on CSP sites that experience a high frequency of calm (no-wind) conditions.

Numerical investigation on the performance of a small scale solar chimney power plant for different geometrical parameters

In recent decades, demand for energy has been significantly increased, and considering environmental impacts and the degrading nature of fossil fuels, clean and emission-free renewable energy production has attracted a great deal of attention. One of the most promising renewable energy sources is solar energy due to low cost and low harmful emissions, and from the 1980s, one of the most beneficial applications of solar energy is the utilization of solar chimney power plants (SCPP). A SCPP is a simple and reliable system that consists of three main components; a solar collector, a chimney (tower) and a turbine to utilize electrical energy. Recently, by the advancement in computer technology, the use of CFD methodology for studying SCPP has become an extensive, robust and powerful technique. In light of the above, in this study, numerical simulations of a SCPP through three-dimensional axisymmetric modeling is performed. A numerical model is created using CFD software, and the results are verified with an experimental study from the literature. After ensuring good agreement with the experiments, chimney’s and collector’s geometric parameters effects and different configurations effects on SCPP performance, simultaneously and additively is investigated. The study introduces an insight to the performance enhancement methods and finding the best configuration of a SCPP model, which will be the basis of a detailed prototyping process. Based on the numerical results, the best configuration of the SCPP has been found as the diverging chimney which enhances the generated power. The results of the study showed that the chimney height and collector radius increase has a positive effect on the power output and efficiency of the system, but when construction and material costs are also considered, each has an optimal value. The maximum impact on the performance is found to be by the chimney tower radius and the collector height and inclination are found to have optimum values considering performance. According to the obtained results, the best performance for the SCPP was obtained with 3.5 m chimney height, 30 cm tower diameter, 400 cm of collector diameter with 6 cm height and zero inclination angle. By the correct selection of the dominant performance parameter which can be done by correctly interpreting the results of this study, “the best” design of a SCPP real scale prototype considering maximum power requirement can be done.

OPTIMIZATION OF A SMALL SOLAR CHIMNEY

An optimization study to maximize the exergy efficiency of a small-scale solar chimney was carried out. Optimization variables include collector diameter (Dc), collector height (Hc), tower height (Ht), and tower diameter (Dt). Models from the literature were used to predict environmental and airflow parameters. Exergy efficiency and solar chimney efficiency were determined, on an hourly basis, for a one-year period. The model was simulated using the EES software. Two methods of optimization were used, the method of conjugate directions and the method of variable metric, both providing similar results. Results were compared to the results from an experimental prototype, and it was found that the energetic and exergetic efficiency were significantly improved. The analysis indicated that the height and diameter of the chimney and collector are the most important physical variables in the design of a solar chimney. For both methods, it was found that the maximum exergy efficiency was obtained with a collector height of 0.5 m, a collector diameter of 30 m, a tower diameter of 1 m, and a tower height of 17.8 – 18.8 m. The exergy efficiency was 44 %.

Specification for water balance test of cooling towers

This test procedure describes the evaluation method used to determine the water consumption performance of cooling towers and evaporative cooling equipment, which provides a unified test instrument, test procedure, parameter measurement, test data processing, and test results. This test procedure provides the manufacturer and the owner an objective and fair evaluation, outlines practical methods for monitoring the water consumption performance of cooling towers. The loss of water in cooling tower is measured by U-type liquidometer, and the law of collecting basin liquid level. When the liquid level of the collecting basin decreased by 1 mm, the water quantity loss of one cooling tower diameter D=42 m was 1.38 m3. And cooling tower water loss and specification for water balance test is established. The water quantity loss of cooling tower can be obtained conveniently, accurately and quickly. This provides conditions for further accurate analysis of water quantity loss of cooling tower, etc. It is widely used and has great significance in the hydraulic design of cooling tower, the analysis of air status in the tower, the water balance test to determine the water used in cooling tower, the reduction of water loss and the drift recovery. And provides explicit test procedures that yield results with the highest level of accuracy and consistent with the best current engineering practices and knowledge in this field.

Structural and durability assessment of ECC/concrete dual-layer system for tall wind turbine towers

The increasing consumption of wind energy necessitates the development of taller concrete turbines towers with larger installed rotors. A previous study demonstrated that a dual layer system that incorporates protective layers made from engineered cementitious composites (ECC) improves the durability performance of these towers (Jin and Li, 2019 [1]). However, the introduction of ECC layers could affect the tower design due to its low elastic modulus relative to concrete. This paper first studies the structural impacts of the concrete towers with added ECC layers. An iterative method is employed to examine the requirements of strength, deflection, natural frequency and fatigue. The results show that ECC protective layer produces nonconsequential effects on tall concrete towers with less than 4% increase in tower diameter. After satisfying the aforementioned requirements, a durability analysis is conducted to compare the tower designs with and without ECC layers. The results indicate that the application of ECC layers significantly delays the initiation of chloride-induced corrosion of steel reinforcement and prolongs the service life of concrete wind turbine towers by four times. Therefore, this study allays the concerns that ECC protective layers may compromise the tower’s structural performance and confirms its potential application in tall wind turbine towers for improved durability performance.

Pilot-scale experiment and simulation optimization of dual-loop wet flue gas desulfurization spray scrubbers

The efficiency of wet flue gas desulfurization (WFGD) used in thermal power plants that burn high-sulfur coal can be improved by adopting dual-loop spray tower (DLST). In this paper, the process of gas–liquid flow, mass transfer and chemical reaction in the DLST were fully investigated through a pilot-scale DLST and the corresponding numerical model. The numerical model was verified based on the experiment and applied to predict a DLST of 200MW coal-fired unit. Investigation results show that higher the inlet SO2 concentration, more significant advantage on improving the desulfurization efficiency for DLST. The mass transfer resistance of liquid-film is still the main effect of SO2 absorption for the upper and lower loops in DLST. The ratios of the gas-film resistance to liquid-film resistance in the upper and lower loops are 0.65 and 0.35, respectively. The designed size of the bowl separator has a significant effect on the system resistance loss. The minimum ratio between the diameter of the bowl and the diameter of the desulfurization tower to avoid “flooding” phenomenon above the bowl separator is about 0.7. Furtherly, the lowest system operating resistance loss can be obtained when the ratio is about 0.82. The simulation results of the desulfurization efficiency and system resistance loss agree well with the test data.

Dynamic Modeling of Wind Turbines Based on Estimated Wind Speed under Turbulent Conditions

Large-scale wind turbines with a large blade radius rotates under fluctuating conditions depending on the blade position. The wind speed is maximum in the highest point when the blade in the upward position and minimum in the lowest point when the blade in the downward position. The spatial distribution of wind speed, which is known as the wind shear, leads to periodic fluctuations in the turbine rotor, which causes fluctuations in the generator output voltage and power. In addition, the turbine torque is affected by other factors such as tower shadow and turbine inertia. The space between the blade and tower, the tower diameter, and the blade diameter are very critical design factors that should be considered to reduce the output power fluctuations of a wind turbine generator. To model realistic characteristics while considering the critical factors of a wind turbine system, a wind turbine model is implemented using a squirrel-cage induction motor. Since the wind speed is the most important factor in modeling the aerodynamics of wind turbine, an accurate measurement or estimation is essential to have a valid model. This paper estimates the average wind speed, instead of measuring, from the generator power and rotating speed and models the turbine’s aerodynamics, including tower shadow and wind shear components, without having to measure the wind speed at any height. The proposed algorithm overcomes the errors of measuring wind speed in single or multiple locations by estimating the wind speed with estimation error less than 2%.

Performance analysis and quantitative design of a flow‐guiding sieve tray by computational fluid dynamics

AbstractAn evolution of the traditional sieve tray, the flow‐guiding sieve tray (FGST), has been utilized in many separation processes, especially for handling viscous systems. The objectives of this work are to optimize the design process of FGSTs and realize the full potential of their separation performance. A computation fluid dynamic (CFD) model that incorporated the modified interphase momentum transfer term was developed. Simulated measures of hydrodynamic performance, such as pressure drop, weeping, entrainment, and clear liquid height agree well with the experimental data, thus verifying the accuracy and reliability of the CFD model established in this work. Furthermore, based on the obtained hydrodynamic parameters, a quantitative model for designing flow‐guiding holes was established and validated by modifying an experimental FGST (diameter 476 mm) and reconstructing an industrial sieve‐tray tower (diameter 1,200 mm). The hydrodynamic parameters and quantitative model are of vital importance for better design and further modification of FGST.

Numerical simulation of thermal performance for super large-scale wet cooling tower equipped with an axial fan

For the super large-scale natural draft wet cooling towers (S-NDWCTs), the higher rain zone produces water dropping potential energy which can be used to drive an axial fan, meanwhile, the larger diameter deteriorate the whole ventilation performance. Based on these issues, a three dimensional (3D) numerical model for a S-NDWCT equipped with an axial fan was established to analyze the thermal performance at different fan diameters and fan power. In order to evaluate the influence of fan, one dimensionless number m, represents the ratio between the fan diameter and the cooling tower diameter, was introduced in this paper, as well as air velocity uniformity coefficient ψvel and air temperature uniformity coefficient ψtem. Simulation results manifested that, compared with natural draft pattern, the thermal performance and ventilation performance of S-NDWCT with an axial fan improve partly according to these two uniformity coefficient and several thermal performance parameters, and they improve continuously with the increasing of fan diameter and fan power. At the given fan rotate speed (20 rpm), the water temperature drop ΔT, ventilation rate G, Merkel number N and cooling efficiency η enhance persistently as the diameter of the fan increases, while these parameters enhance firstly, and then reduce at the given power (300 kW). Under 15.0 m fan diameter (m = 0.125) and 300 kW fan power conditions, compared with natural draft pattern, ΔT, G, N, and η all reach to the maximum of 9.31 °C, 31,549 kg/s, 1.65 and 53.5%, and enhance by 0.14 °C, 611 kg/s, 0.04 and 0.8%, respectively. It demonstrates that the cooling tower shows out the outstanding thermal and ventilation performance when the diameter ratio m is 0.125.

Coupled wind turbine design and layout optimization with nonhomogeneous wind turbines

Abstract. In this study, wind farms were optimized to show the benefit of coupling complete turbine design and layout optimization as well as including two different turbine designs in a fixed 1-to-1 ratio in a single wind farm. For our purposes, the variables in each turbine optimization include hub height, rotor diameter, rated power, tower diameter, tower shell thickness, and implicit blade chord-and-twist distributions. A 32-turbine wind farm and a 60-turbine wind farm were both considered, as well as a variety of turbine spacings and wind shear exponents. Structural constraints as well as turbine costs were considered in the optimization. Results indicate that coupled turbine design and layout optimization is superior to sequentially optimizing turbine design, then turbine layout. Coupled optimization results in an additional 2 %–5 % reduction in the cost of energy compared to optimizing sequentially for wind farms with turbine spacings of 8.5–11 rotor diameters. Smaller wind farms benefit even more from coupled optimization. Furthermore, wind farms with closely spaced wind turbines can greatly benefit from nonuniform turbine design throughout the farm. Some of these wind farms with heterogeneous turbine design have an additional 10 % cost-of-energy reduction compared to wind farms with identical turbines throughout the farm.

Optimization of turbine design in wind farms with multiple hub heights, using exact analytic gradients and structural constraints

AbstractWind farms are generally designed with turbines of all the same hub height. If wind farms were designed with turbines of different hub heights, wake interference between turbines could be reduced, lowering the cost of energy (COE). This paper demonstrates a method to optimize onshore wind farms with two different hub heights using exact, analytic gradients. Gradient‐based optimization with exact gradients scales well with large problems and is preferable in this application over gradient‐free methods. Our model consisted of the following: a version of the FLOw Redirection and Induction in Steady‐State wake model that accommodated three‐dimensional wakes and calculated annual energy production, a wind farm cost model, and a tower structural model, which provided constraints during optimization. Structural constraints were important to keep tower heights realistic and account for additional mass required from taller towers and higher wind speeds. We optimized several wind farms with tower height, diameter, and shell thickness as coupled design variables. Our results indicate that wind farms with small rotors, low wind shear, and closely spaced turbines can benefit from having two different hub heights. A nine‐by‐nine grid wind farm with 70‐meter rotor diameters and a wind shear exponent of 0.08 realized a 4.9% reduction in COE by using two different tower sizes. If the turbine spacing was reduced to 3 diameters, the reduction in COE decreased further to 11.2%. Allowing for more than two different turbine heights is only slightly more beneficial than two heights and is likely not worth the added complexity.

Upwind 2MW Horizontal Axis Wind Turbine Tower Design and Analysis

Wind energy is one of the quickest growing renewable energies in the world due to era of wind energy is smooth and non-polluting; it does now not produce any byproducts dangerous to the environment. Large scale machines are in particular nicely appropriate for wind energy. The fee of foundations doesn’t upward push in share to the dimensions of the device, and protection costs are largely impartial of the size of the system. In areas where it is difficult to find sites for more than a single turbine, a large turbine with a tall tower uses the existing wind resource more efficiently. Different subcomponents are designed depend on the purpose of the turbines among these the tower of a wind turbine helps the nacelle and the rotor and affords the necessary elevation of the rotor to hold it clear off the floor and produce it as much as the level where the wind sources are. The towers for large wind turbines are typically made from steel; however concrete towers are every so often used. The tower is normally connected to its helping basis by using a bolted flange connection or a weld. The tower constitutes a low-generation aspect whose layout is easy to optimize, and which therefore for the duration of the layout manner lends itself easily as an item for possible fee discount. This may additionally are available in useful because the fee of a tower typically establishment a sizeable a part of the entire fee of a wind turbine. The design and analysis of the tower focused on large wind turbines. It examines the result of loading on the tower, the optimum tower height and the verification of safety against bending and buckling. The buckling of 2 MW horizontal axis wind turbine tower tube with tower base diameter of 3.9m, top tower diameter of 2m and length of 80m is studied by theoretical analysis and numerical simulation by using ANSYS and MATLAB software. Based on this study the results are calculated based on theoretical and FEM method and their error is shown, buckling modes and vibrational analysis are done, shear and bending diagrams are shown, extreme loading conditions are also shown.