Performance Of Tower Research Articles

Effect of Fly Ash on the Mass Transfer Performance of CO2 Removal Using MEA and DEA Solutions in a Packed Tower

The accumulation of uncollected fly ash from flue gas in post-combustion CO2 capture processes is a significant concern in current coal-fired power plants due to its potential impact on the performance of CO2 absorbent and absorption towers. In order to determine the effect of fly ash on the mass transfer performance of CO2 absorption into monoethanolamine (MEA) and diethanolamine (DEA) aqueous solutions, experimental studies were carried out using a small-sized packed tower equipped with θ-ring random packing. These studies were conducted under various operating parameters, including solution temperature, liquid/gas ratio (L/G), packing height, and fly ash concentration. The results show that the effect of fly ash on the outlet CO2 concentration was primarily observed during the initial stages of the experimental process. Moreover, the presence of fly ash leads to a reduction in the volumetric overall mass transfer coefficient (KGav) when using MEA and DEA solution, and increasing the fly ash concentration further exacerbates this negative impact. However, the effect of fly ash on the reduction in KGav is not significantly related to its chemical composition but rather depends on the operational parameters. With increasing solution temperature, liquid/gas ratio (L/G), and packing height, the KGav values for different solutions exhibit an upward trend. The negative effect of fly ash on KGav remains relatively stable for MEA as solution temperature and packing height increase. Compared to MEA, fly ash has a greater negative effect on DEA solution under the same experimental conditions. The analysis reveals that the detrimental effect of fly ash on KGav primarily stems from its ability to alter the distribution state of the absorption liquid within the packed tower.

Nonlinear Performance of Steel Tube Tower in Ultra-High Voltage Transmission Lines under Wind Loads

As complex, statically indeterminate structures, transmission towers are subject to complex forces and are usually simplified into truss structures that only consider the effects of axial force. When the load and deformation of a tower are small, it is reasonable to carry out analysis according to the linear elasticity theory. However, the height of an ultra-high voltage (UHV) transmission tower is significantly large, meaning that the calculation result according to the current elastic analysis method often has a large deviation from the actual stress of the structure. With the influence of the bending moment at the end of the member, a numerical model is established considering the influence of geometric nonlinearity and material nonlinearity in this paper. The stress distribution characteristics and development law of UHV transmission towers in linear and nonlinear stress states are analyzed and studied. The real tower test and elastoplastic ultimate bearing capacity analysis show that the elastoplastic analysis is closer to the actual tower. The UHV steel pipe tower designed according to the linear elasticity and small deformation theory has a large safety margin under the design load, resulting in a significant waste of materials. Under the action of heavy load, the tower exhibits strong nonlinearity, and the influence of geometric and material nonlinear factors should be fully considered when designing the structural components in UHV transmission towers.

Studi Performa Cooling Tower berdasarkan Kualitas Air Pendingin

Cooling water is used to cool fluids with a high temperature in a closed system, such as a cooling tower or heat exchanger. Sometimes, the cooling water is specified in a long tube, which risks fouling and rusk. This research will study cooling water quality as Total Dissolved Solid (TDS), chlorine concentration, and antiscale. In the design of the cooling tower at PLTGU Tanjung Uncang, the range or limit of the permitted TDS is 50,000. If this figure has been reached, the cooling tower must be blown down. Blowdown is water in the cooling tower that is deliberately removed to avoid the concentration of impurities during heat evaporation. At PLTGU Tanjung Uncang, the permitted chlorine concentration is in the range of 0.2-0.5. Chlorine flow in the cooling tower at PLTGU Tanjung Uncang is reversed with Cl concentration and TDS. Inject Antiscale aims to maintain cooling tower performance, which aims to be anti-rust.

Thermo-economic analysis of the impact of the interaction between two neighboring dry cooling towers on power generation of dual thermal power units and the energy-efficient operation strategy

Thermo-hydraulic behavior of the dry cooling tower and thermodynamic performance of the power unit was coupled by a well-developed computational framework. The interaction between two neighboring towers was detected through a numerical model under variable working conditions, and the impact of cooling performance variation of each tower on cycle efficiency of the corresponding unit was quantified by a thermo-economic model. Results showed that tower interaction mostly impacts heat rejections of radiators at the neighboring halves of both towers. A higher unit load ensures both towers better cooling performances subject to crosswind. The unfavorable wind-effect on cooling behavior of the upstream tower mitigates with increasing wind attack angle, while that on the downstream tower varies little initially and drops sharply as wind attack angle approaching 90°. For each unit, thermodynamic cycle efficiency is more sensitive to crosswind under a higher unit load. Cycle efficiency grows with unit load at low wind speeds, but generally increases and then decreases with unit load at medium–high wind speeds. Dual units should operate at the same load to maximize operational energy efficiency. Otherwise, the unit corresponding to the upstream tower should follow higher and lower load commands under small-medium and large wind attack angles, respectively.

Wind damage vulnerability analysis of narrow base tower for distribution line based on probabilistic reliability

Steel narrowbase tower has been widely used in distribution network in recent years because that it covers an area smaller than the conventional tower, and has stronger wind resistance than concrete pole. In order to fully understand the wind resistance performance of narrow base tower, a vulnerability performance of narrow base tower under different wind speeds was analyzed based on probabilistic reliability theory. According to the damage characteristics of narrow base tower and the corresponding tall structure specification, wind performance level indexes of narrow base tower were established. When calculating the effect of wind load on narrow base tower, the randomness of wind load, material properties and dimensions were considered. The probability of the narrow base tower appearing different degrees of damage under different wind speeds was calculated, and subsequently a wind vulnerability curve of the narrow base tower was drawn. It is found that the severe damage probability of narrow base tower is about 5% when the wind speed is 23.6m/s. And in the case of severe damage probability is 95%, the wind speed reaches 80m/s. Narrow base tower has good resistance to wind disaster.

Assessing outdoor comfort near graduation towers: An experimental calibration study in a public open space

This study focuses on the experimental calibration of a numerical model to quantify the cooling effects of graduation towers under heat wave conditions. Given the increasing number of hot days, tropical nights and ongoing urbanization, simulation tools for predicting and enhancing outdoor comfort have become increasingly important. To investigate the influence of the water mist emitted by the graduation towers, a 3D model was constructed using the microclimate simulation tool ENVI-met and calibrated against in-situ measurements. By means of evaporation, both air temperature and PET (Physiological Equivalent Temperature) could be reduced by up to 14.8K and 9.5K, respectively, resulting in no thermal stress in the vicinity of the graduation towers. The calibrated model can assist municipalities in assessing the cooling performance of graduation towers, enabling them to adjust water usage according to weather conditions and enhance outdoor comfort for the well-being of the population in recreational areas.

A liquid desiccant-assisted free-cooling system for energy-efficient data centers in hot and humid climates

Air conditioning and cooling are essential to ensure the reliable operation of data centers. Several studies have been conducted regarding the use of free cooling for energy-efficient cooling. However, free cooling faces challenges when used in hot and humid environments, which can lead to a decline in cooling tower performance. To address this issue, we propose a cooling system that utilizes a liquid desiccant to lower the humidity and improve the performance of the cooling tower, thereby reducing the energy consumption of the refrigeration system. Simulations were conducted in areas where the data centers were located, considering hot and humid climates. According to the simulation results, it was possible to achieve an average reduction of 35.12 % in cooling energy consumption by improving the performance of the cooling tower.

Influence of the air-cooled supercritical carbon dioxide recompression cycle design-point on molten salt power tower techno-economic performance

This paper investigates the techno-economic performance of a molten salt power tower integrated with an air-cooled supercritical carbon dioxide recompression cycle. Prior research into the cycle design point showed trade-offs between efficiency, cost, and temperature difference across the heat input, resulting in trade-offs between the design-point generation of the molten salt power tower system and the cost of sensible-heat thermal energy storage. Prior research into cycle off-design showed that colder ambient temperature designs have higher efficiencies on cold days but lower efficiency and capacity degradation on hot days. We present a framework to evaluate how cycle design, cost, and corresponding off-design performance affect the techno-economic performance of the molten salt power tower system. We use a steady-state off-design cycle model assuming fixed shaft speeds, inventory control, and air-cooler fan power control and integrate the cycle model with the molten salt power tower model from the National Renewable Energy Laboratory’s System Advisor Model. First, we present a surrogate model that uses a heuristic approach to correct the interpolation when the cycle reaches capacity limitations at ambient temperatures hotter than design. Next, we evaluate how the recompression cycle design-point ambient temperature, air-cooler approach temperature, air-cooler fan power, and recuperator conductance influence cycle and system design metrics. Finally, we complete annual simulations using an hourly “duck curve” pricing schedule and present annual performance metrics to evaluate the cumulative effects of the cycle design parameters and corresponding off-design performance on molten salt power tower techno-economics.

Development of seismic fragilities for a base station steel lattice cellular tower

A large portion of the country of Turkey is located in a very high seismic region known as a first-degree earthquake zone where earthquakes occur frequently. Earthquakes result in damage to infrastructure including base station towers and subsequently failure of mobile communication networks. The loss of functionality of mobile communication networks following an earthquake has a direct impact on emergency response and both short and long-term recovery phases. Understanding both these phases requires systematic modeling of infrastructure components, which rely on fragility curves representing the probabilistic relationship between seismic intensity and damage. This study focuses on the development of damage fragility curves (fragilities) for an archetypical mobile cellular tower, namely a 55 m tall steel lattice tower (SLT) used in base station towers in Turkey. Nonlinear time history analysis was performed using a robust suite of far field ground motion records to model the performance of the archetype tower and develop damage fragilities for five specific damage states which were defined in terms of likely performance: damage state 0 (no damage), damage state 1 (uninterrupted communication), damage state 2 (communication interruption), damage state 3 (communication failure), damage state 4 (structural failure). While fragility curve has been developed for lattice towers of different types and sizes in the literature, there is no specific study for 55 m SLT and the novelty of this study is that the resulting SLT archetype fragilities can serve as a benchmark dataset for use in community-level risk and resilience analyses to improve response and recovery planning following earthquakes.

Computational study of multiphase flow in cement plant gas conditioning towers: a review

Gas conditioning towers (GCTs) or cooling towers have broad industrial applicability, especially in the cement industry. Most cement factories deal with the same problems faced by other factories. However, the solutions to these problems are barely internationally published and have not received much attention, meaning a lot of time and money is spent on researching previous solutions. Iran is among the top ten cement manufacturing countries in the world. Therefore, many of these problems have occurred in Iranian cement factories. The purpose of this paper is to provide a review of studies in this field over the last couple of decades, with a particular focus on advances in Iran. The most important findings in the literature are summarised in order to suggest the best possible solutions for improving the performance and lifetime of GCTs and decreasing common problems such as dust build-up and wet bottom. Numerical methods for modelling different aspects of GCTs are reviewed. The results can be used to reduce water and energy consumption, air pollution and the repair and maintenance costs of cement factories.

Recent Progress in Fill Media Technology for Wet Cooling Towers

Cooling towers are extensively utilized in diverse industries for efficient heat dissipation. Fill media are a critical component, facilitating heat and mass exchange between water and air, impacting overall cooling tower efficiency. Given its vital importance, this study comprehensively reviews recent advancements in fill media technology, illuminating cooling tower technology progress and exploring the effects of different fill media configurations and materials on cooling tower performance. It should be noted that the majority of research is focused on the Range of 2.5 °C to 25 °C and Approach of 1 °C to 9 °C. Through comprehensive analysis and evaluation, the effects of various fill media on heat transfer efficiency, water cooling capacity, and energy consumption are intensively summarized. By understanding these effects, engineers and designers can make rational decisions to optimize cooling tower performance and ensure efficient heat dissipation. Notably, in some reported cases, new fill media enhanced cooling range, effectiveness, and the Merkel number by 28%, 85%, and 131%, respectively. Ultimately, this paper serves as a valuable resource for academics, researchers, and professionals in the field of cooling tower design and thermal management. The insights provided in this study can help industries achieve greater energy efficiency, sustainability, and overall operational excellence.

Experimental and analytical study on the performance of wind turbine tower attached with particle tuned mass damper

According to the global wind energy council report, a dramatic increase in the annual wind installations is needed to satisfy the goal of net-zero, which means there will be a large market for wind turbine towers. Therefore, the safety and suitability of wind turbine towers must be ensured by certain methods under wind and seismic excitations for reliable wind energy production. This paper presents a comprehensive study involving experimental, analytical, and computational approaches to study the performance of the particle tuned mass damper (PTMD) that is attached to a 1/20 scaled wind turbine tower model through a shaking table test. During the test, the overall performance of PTMD is analyzed under earthquake and equivalent wind excitations. The results indicate that PTMD can significantly mitigate the dynamic responses of the tower top and tower body. Then, a parametric study of PTMD is carried out to detail its damping mechanisms. The results show that the robustness of PTMD is good, and PTMD possesses a wider vibration control frequency band. Finally, based on the experimental test, a finite element model is built, and then a comparison of experimental and numerical results is conducted to investigate the vibration reduction effect of PTMD under coupled wind and earthquake excitations. The numerical simulation and experimental results agree well, and PTMD has good vibration reduction effectiveness under coupled wind and earthquake excitations. Besides, the numerical simulation indicates that aerodynamic damping can restrain the vibration of the wind turbine tower to a certain extent. Both the experimental and numerical results indicate that the PTMD can reduce the vibration of wind turbine towers significantly under wind and earthquake excitations.

Feature Enhancement Using Multi-Baseline SAR Interferometry-Correlated Synthesis Images for Power Transmission Tower Detection in Mountain Layover Area

The detection performance of power transmission towers in mountainous areas using SAR amplitude images is obviously influenced by the strong layover background (mainly including vegetation and soil) clutter interference around the towers. In this paper, power transmission tower detection in a mountainous layover area, using single-baseline SAR interferometry coherence images, which show better feature enhancement effectiveness compared to SAR amplitude images, is presented. Moreover, a novel feature enhancement method, that of generating multi-baseline SAR interferometry-correlated synthesis images for power transmission tower detection in a mountain layover area, is proposed. It demonstrates better feature enhancement (layover background cluster suppression) than that using single-baseline SAR interferometry coherence images. Theoretical analysis illustrates that the mountainous layover background clutter interference can be suppressed in the proposed single-baseline/multi-baseline SAR interferometry-correlated synthesis image. Experiments including over 12 repeat-pass TerraSAR-X staring spotlight mode acquisitions were conducted, and the results demonstrate that the detection performance with the use of multi-baseline SAR interferometry-correlated synthesis images showed an improvement of more than 43.6%, compared with the traditional method of using SAR amplitude images when benchmark deep learning-based detectors are used, i.e., Faster RCNN and YOLOv7.

Experimental Investigation into the Heat and Mass Transfer in an Indirect Contact Closed Circuit Cooling Tower

The heat and mass transfer coefficients of the indirect contact closed circuit cooling tower, ICCCCT, were investigated experimentally. Different experiments were conducted involving the controlling parameters such as air velocity, spray water to air mass flow rate ratio, spray water flow rate, ambient air wet bulb temperature and the provided heat load to investigate their effects on the performance of the ICCCCT. Also the effect of using packing on the performance of the ICCCCT was investigated. It was noticed that these parameters affect the tower performance and the use of packing materials is a good approach to enhance the performance for different operational conditions. Correlations for mass and heat transfer coefficients are presented. The results showed a good agreement with other published works. Correlations are showed that the spray heat transfer coefficient is a function flow rates of spray water and air as well as spray water temperature while mass transfer coefficient is a function of spray water and air flow rates only.

Analysis of the Effect of Packing Materials (Fills) and Flow Rate on the Range and Efficiency of a Forced Draft Evaporative Cooling Tower

In the present study, experimental investigation is carried out on two different kinds of packing materials (fills). PVC fills that are traditionally used in the industry are compared and analyzed against the cellulose-based paper fills. Different mass flow rates of air are used to study the effect of the flow rate of air on the forced draft cooling tower. The volume flow rate of water also varied, and the range of the cooling tower, along with efficiency, was analyzed. Along with these two parameters, the effect of inlet water temperature on the performance of the tower was studied. Cooling tower efficiency was plotted against different L/G ratios ranging from 0.95 to 7.67. Results showed that the type of packing has a significant impact on the cooling tower performance. Paper fills gave a maximum cooling tower efficiency and range equal to 93.12% and 16.5 °C, respectively. The optimal L/G ratio range of 0.96 to 1.44 was identified as the point at which the cooling tower demonstrated its highest performance. The effect of the mass flow rate of water on the performance of the tower was far greater compared to the volume flow rate of water and inlet water temperature. The paper fills are found to be most effective under current experimental conditions, and the same can be implemented in the industrial towers under a wide spectrum of inlet water temperatures, mass flow rates of air, and volume flow rates of water.

Correction to: An interdisciplinary investigation of the seismic performance of a historic tower in Istanbul during the 1999 Kocaeli earthquake

Correction to: An interdisciplinary investigation of the seismic performance of a historic tower in Istanbul during the 1999 Kocaeli earthquake

Assessing parallel path cooling tower performance via artificial neural networks

Real-time monitoring of a research nuclear reactor, a system in which all generated power is dissipated to the environment, can be performed via analysis of the heat rejection from the cooling system. Given an inlet water temperature and flow rate, the reactor power can be well-approximated from the outlet water temperature; however, the instrumentation to measure outlet conditions may not be robust or accurate. If we know how a cooling tower performs from historical data, but cannot measure the outlet temperature, a mathematical representation of the system can be inverted to obtain the outlet water temperature that describes the cooling capacity. Unfortunately, model inversion processes are computationally expensive. To address this, an artificial neural network (ANN) is implemented to assess the performance of a multi-cell cooling tower for a nuclear reactor. This approach leverages the Merkel model to obtain an extensive data set describing performance of the cooling tower cells throughout a wide array of potential operating conditions. The Merkel model is expressed as a function of four parameters: the inlet and outlet water temperatures, inlet air wet bulb temperature, and ratio of liquid-to-gas mass flow rates (L/G), which together provide a non-dimensional number indicative of cooling tower performance, called the Merkel integral. Computing a 4-dimensional data structure that describes finite combinations of the Merkel integral, an inverse model is then generated using an ANN to determine the cell outlet water temperature from the other three model parameters along with the computed Merkel integral. Compared to traditional model inversion methods, the ANN reduces the computational time by approximately 4 orders of magnitude, with effectively no sacrifice to solution accuracy, and could be applied for different cooling towers in the event the performance curve is known. Three use cases of the ANN are then reviewed: (1) determining the cell outlet water temperatures when gas flow at rated conditions (GFRC) is known, (2) performing the prior case without knowledge of the GRFC, and (3) assessing performance differences between the individual tower cells.

Earthquake response and damage patterns assessment of two historical masonry churches with bell tower

The earthquake response of two historical masonry churches is investigated through a finite element macro-modelling approach and non-linear dynamic analyses. The main aim of the study is to evaluate the church walls effects on the seismic performance and damage patterns of slender bell towers, which are analyzed also in the isolated configuration to perform a comprehensive comparison with the confined counterpart. The results of the numerical simulations point out that both the churches, which present different sizes, structural features and dynamic properties, are highly vulnerable to low-to-moderate seismic actions and the bell tower is one of the most critical elements, suffering widespread damage due to also the interactions effects with the neighboring church walls. The presence of shorter adjacent structural elements significantly modifies the main structural dynamic characteristics, seismic response and damage patterns of the bell tower. For both the confined towers, the first cracks originate in the connection regions with the adjacent church walls: on the other hand, for both the isolated towers, the first cracks originate mainly at the base. An advance of damage onset is also detected in the case of confined towers with respect to isolated towers. At the end of the numerical analyses, for both the case studies, the confined configurations show more remarkable damage patterns and larger values of energy density dissipated by tensile damage than the isolated ones, presenting relevant cracks concentrations mostly near the connection regions with the church walls and in the middle-upper part of the bell tower. The results of this study emphasize the paramount importance of taking into account the interactions effects with the surrounding church walls for a proper damage and failure mechanisms assessment of bell towers within the church context: simplified analyses performed on isolated configurations without considering such interaction effects may lead to significant underestimations of damage for the bell tower inside the church.

Reliability assessment for hybrid solar tower under near-fault pulse-like ground motions using Kriging surrogate and subset simulation

Concentrated solar towers are commonly designed as high-rise hybrid structures, which exhibit properties of non-uniform mass and rigidity along the height of the tower, and consequently are vulnerable to strong seismic ground motions. This study presents a comprehensive analysis of the seismic performance of a hybrid solar tower, which is one of the tallest hybrid solar towers in the world. The hybrid solar tower includes a reinforced concrete tube at the bottom and a steel-truss tube at the top and is subjected to near-fault pulse-like ground motions. A simulation technique that utilizes the stochastic point-source model and a velocity pulse model was introduced to generate stochastic pulse-like ground motions. The stochastic response of the hybrid solar tower to near-fault pulse-like ground motions was computed to estimate the tower’s reliability. To enhance the efficiency of reliability estimation, an algorithm combining the Kriging surrogate and subset simulation (K-SS) was presented. The aggregate response of the tower was found to be significantly more damaging over the border of the reinforced concrete tube and the steel-truss tube than below the border. The study found that the hybrid solar tower has a reliability of 90.53% when subjected to stochastic near-fault pulse-like ground motions with a peak ground acceleration of 0.62 g. The findings of this study contribute to the understanding of the seismic performance of high-rise hybrid solar towers under near-fault pulse-like ground motions.

Influence mechanism of the louver on the thermal performance of the mechanical draft wet cooling tower

To explore the performance influence of louvers on mechanical draft wet cooling towers (MCTs), the specific structure of the louver is described in this paper. The inclination angle of louvers, crosswind velocity, and crosswind direction are taken as the main study variables. Numerical analysis is employed to elaborate the impact mechanism of louvers on tower performance under crosswinds, by estimating the airflow distribution, air-water ratio distribution, ventilation capacity, and outlet water temperature. Results show that the thermal and ventilation performance of MCTs can be regulated in a large range by controlling the inclination angle of louvers. Compared with the MCT without the louver, the variation range of ventilation rate is −16.45 % to 6.25 %, and that of outlet water temperature is −0.73 °C to 0.81 °C. The MCT has the best thermal performance when the inclination angle of louvers is 90°, with an average decrease of outlet water temperature by 0.40 °C under the crosswind angle of 0°, 0.36 °C under that of 45°, and 0.25 °C under that of 90°. With the increase of the inclined angle of the louver, the influence range of the longitudinal vortex on the upper edge of the air inlet of the MCT gradually declines or even disappears. The current findings can promote efficient regulation of the thermal performance of the MCT by adjusting the inclination angle of the louver.