Cooling Tower Research Articles

Onsite Wastewater Treatment Upgrade for Water Reuse in Cooling Towers and Toilets

The increasing population size and housing density are responsible for greater consumption of water resources, causing drinking water shortages in many regions. To reduce water consumption, it is essential to perform wastewater treatment, particularly in onsite non-potable water systems (ONWS). This article discusses the performance of a wastewater treatment system in a shopping mall in Brazil (City of Guarulhos, São Paulo State, Brazil), using data collected over 3 years (2015–2018) that resulted in water reuse ranging from 12 to 42 m³ per day. The strategy used for this wastewater treatment and further reuse in cooling towers and toilets initially included nine steps; after adjustments, an additional step (tertiary decanter) was added. All steps were named as follows: (1) railing; (2) fats boxes; (3) aerobic reactors with selector tank; (4) denitrification; (5) flocculation; (6) secondary decanter; (7) ultrafiltration; (8) disinfection; (9) filtration by zeolites; and (10) tertiary decanter. Based on using FeCl3 as a flocculant followed by filtration by zeolites (SFM) for ion adsorption and removing above 99% of the biological oxygen demand (BOD5), generating a final BOD5 of <2.0 mg/L, total dissolved solids of 130 to 594 mg/L, pH ranging from 6.75 to 7.79, and remaining pathogen-free. This treatment demonstrated the feasibility of reusing water in air conditioning cooling towers and toilets, generating up to 797 m³/month of treated water for reuse with savings of up to 27% in drinking water consumption at the mall.

Heat and Mass Transfer of a Gas–Air Mixture in the Stack of an Evaporative Cooling Tower

Heat and Mass Transfer of a Gas–Air Mixture in the Stack of an Evaporative Cooling Tower

Coupled CFD and 3E (Energy, Exergy and Economical) analysis of using windbreak walls in heller type cooling towers

Generally, Montazer Ghaem Combined Cycle Power Plant (MGCCPP) is equipped with natural draft dry cooling towers (NDDCT) and its performance strongly depends on environmental conditions such as wind speed. Thus, the present study aims to evaluate the effects of wind blowing on the cooling towers (CTs) efficiency and propose methods to improve their performance. It can help increase plant efficiency and decrease energy loss, which leads to cleaner production. For this purpose, the cycle of MGCCPP is modeled simultaneously using CFD and energy-exergy analyses for the first time. Moreover, the effect of windbreak walls (WBWs) on CT performance and CCPP are addressed. The results of CFD analyses are used to recognize the behavior of the towers in different wind speeds and deriving heat rejection. Based on obtained results, using the WBW in the prevailing wind leads to about 6.5 MW excess power in each unit. According to the economic analysis, the payback period of the three proposed plans is 14, 15.5, and 16 months, which is fully justified.

Typhoon-Induced Failure Process and Collapse Mechanism of Super-Large Cooling Tower Based on WRF-CFD-LS/DYNA Nesting Technology

There have been several cases of large cooling towers being damaged by wind in history. A typhoon has the characteristics of a strong wind field energy and large shear wind speed. This paper simulates the entire collapse process of large hyperbolic cooling towers by the action of typhoons and refines the typhoon-induced failure mechanism for cooling towers. Firstly, based on WRF-CFD wind field downscaling technology, a fine simulation of the near-ground multiscale wind field produced by China’s strongest typhoon “Typhoon Rammasun” is performed to extract effective three-dimensional (3D) typhoon load input parameters. Then, by loading the obtained 3D wind load on the finite element model, a pseudo-dynamic analysis of the world’s tallest cooling tower “Luan Cooling Tower” is performed based on LS-DYNA explicit dynamic analysis, and the typhoon-induced collapse process is simulated. Finally, the stress distribution and distortions of the tower and the response time history of key units are compared and analyzed to determine the collapse mechanism. The process of collapse begins with large deformation of the windward surface of the tower throat, which shows folds in the range of 62° on both sides. Eventually, collapse occurs due to uncoordinated deformation. The collapse mechanism can be divided into a bending arch mechanism and a suspension wire mechanism.

A New Method for the Simulation of High Reynolds Number Effects on Cooling Tower Models in Wind Tunnels

To protect large cooling towers against strong winds, wind tunnel model tests have traditionally been undertaken. As typical circular cylindrical structures, simulations of high Reynolds number (Re) effects are indispensable on scale models of large cooling towers to validate the truthfulness of test results. However, two issues currently exist that hinder the effectiveness of high Re effects simulation: (1) the mean wind pressure distribution at high Re is usually utilized as the sole simulation target, and the simulation results are not typically checked for other dynamic wind effects that are equally important; and (2) it is not clear whether the wind effects obtained and generalized by other researchers for small-sized cooling towers can be used as simulation targets for large cooling towers. In light of these issues, a new method for the simulation of high Re effects that takes into account real simulated dynamic wind effects is proposed in this study and compared with the traditional simulation method, which only considers the simulation of the mean wind pressure distribution. By comparing the wind effects measured on a 167 m-high large cooling tower with those obtained on small-sized cooling towers, the irrationality of treating the wind effects measured on small-sized cooling towers as high Re effects simulation targets for large cooling towers is demonstrated. With these findings, future model tests are expected to reproduce more realistic wind effects on large cooling towers.

Frequency-Constrained Optimization of a Real-Scale Symmetric Structural Using Gold Rush Algorithm

The optimal design of real-scale structures under frequency constraints is a crucial problem for engineers. In this paper, linear analysis, as well as optimization by considering natural frequency constraints, have been used for real-scale symmetric structures. These structures require a lot of time to minimize weight and displacement. The cyclically symmetric properties have been used for decreasing time. The structure has been decomposed into smaller repeated portions termed substructures. Only the substructure elements are needed when analyzing and designing with the concept of cyclic symmetries. The frequency constrained design of real-scale structures is a complex optimization problem that has many local optimal answers. In this research, the Gold Rush Optimization (GRO) algorithm has been used to optimize weight and displacement performances due to its effectiveness and robustness against uncertainties. The efficacy of the concept of cyclic symmetry to minimize the time calculated is assessed by three examples, including Disk, Silo, and Cooling Tower. Numerical results indicate that the proposed method can effectively reduce time consumption, and that the GRO algorithm results in a 14–20% weight reduction of the problems.

Impact of cooling tower technology on performance and cost-effectiveness of CSP plants

Cooling towers are indispensable components for heat rejection in concentrated solar power (CSP) plants. However, the overall performance of CSP plants relies heavily on the choice of cooling tower technology. This paper aims at assessing the impact of cooling tower technology on CSP plant from performance, economic, and environmental perspectives. To achieve this goal, seven CSP projects worldwide with distinct features were selected, and multiple simulations on System Advisor Model software were performed to evaluate the annual energy production, capacity factor, and levelized cost of electricity (LCOE). Moreover, the impact assessment was performed in terms of key metrics, such as discounted payback period (DPP), savings-to-investment ratio (SIR), greenhouse gases (GHG) emissions, water-saving, and total costs savings (TCS) including energy, carbon and water costs savings.The results showed that the wet cooling technology achieved the highest performance findings followed by hybrid and dry cooling technologies. The environmental analysis revealed that the wet cooling technology could avoid roughly 7.02% and 2.93% of GHG emissions compared to dry and hybrid cooling ones, respectively; however, it was found that dry and hybrid cooling technologies could be more profitable in arid regions with water scarcity, since they could save on average 93.30% and 69.83% of water, respectively, compared to the wet technology. Furthermore, the economic results showed that wet and hybrid cooling towers exhibit the best cost-effectiveness over dry cooling one as the LCOE was found to be $0.231/0.244 per kWh, and the DPP ranged between 13.41 and 23.46/14.95 and 34.75 years by integrating wet/hybrid technologies in CSP plants. Overall, wet and hybrid cooling technologies yield better TCS and SIR outcomes over dry cooling one. However, with respect to energy conservation, water savings, and GHG emissions savings, hybrid cooling tower could be considered as an optimal technology. This paper is expected to be a guideline for selecting the most cost-effective and eco-friendly cooling technology for future CSP plants, based on key criteria.

Bacterial Antagonistic Species of the Pathogenic Genus Legionella Isolated from Cooling Tower.

Legionella pneumophila is the causative agent of Legionnaires’ disease, a severe pneumonia. Cooling towers are a major source of large outbreaks of the disease. The growth of L. pneumophila in these habitats is influenced by the resident microbiota. Consequently, the aim of this study was to isolate and characterize bacterial species from cooling towers capable of inhibiting several strains of L. pneumophila and one strain of L. quinlivanii. Two cooling towers were sampled to isolate inhibiting bacterial species. Seven inhibitory isolates were isolated, through serial dilution plating and streaking on agar plates, belonging to seven distinct species. The genomes of these isolates were sequenced to identify potential genetic elements that could explain the inhibitory effect. The results showed that the bacterial isolates were taxonomically diverse and that one of the isolates may be a novel species. Genome analysis showed a high diversity of antimicrobial gene products identified in the genomes of the bacterial isolates. Finally, testing different strains of Legionella demonstrated varying degrees of susceptibility to the antimicrobial activity of the antagonistic species. This may be due to genetic variability between the Legionella strains. The results demonstrate that though cooling towers are breeding grounds for L. pneumophila, the bacteria must contend with various antagonistic species. Potentially, these species could be used to create an inhospitable environment for L. pneumophila, and thus decrease the probability of outbreaks occurring.

Zero Liquid Discharge and Water Reuse in Recirculating Cooling Towers at Power Facilities: Review and Case Study Analysis

Zero Liquid Discharge and Water Reuse in Recirculating Cooling Towers at Power Facilities: Review and Case Study Analysis

Model Predictive Control of Induced Draft Cooling Towers in a Large Scale Cooling Plant

We study the problem of designing a model predictive control strategy for multiple induced draft cooling towers. The common objective of the cooling towers is to regulate the outlet water temperature of the common collection basin to the desired set point. Each cooling tower can be operated in different modes (bypass, showering, ventilation) to meet the heat rejection requirement. To deal with the interacting dynamics and logic, we propose a model predictive control strategy based on mixed integer programming (MIP) which accounts for the changing weather conditions and active heat load to simultaneously determine the best operational mode and optimal fan speed for each cooling tower. Dwell time constraints are added to avoid excessive switching between different operational modes. Although the proposed formulation can account for different operational efficiencies of the cooling towers, an adaptive penalty is designed to balance the run time among identical cooling towers. The inherent over-actuated structure of the cooling process is exploited to provide robustness against the unavailability of an operational mode of a cooling tower. The efficacy of the proposed approach is demonstrated on experimentally validated models of induced draft cooling towers. Simulation results show significant performance improvements and energy savings over conventional heuristic solutions.

Experimental study of a natural draft hybrid (wet/dry) cooling tower with a splash fill type

<abstract> <p>Cooling towers have such a significant influence on work and efficiency that researchers and designers are working tirelessly to enhance their performance. A prototype design for a natural draft hybrid (wet/dry) cooling tower has been created, relying on geometrical, dynamic, and thermodynamic similarities. Based on Iraqi weather, experiments have been conducted using splash fill (150 mm) in summer (hot and dry) weather conditions. This study investigated heat transfer mechanisms of both air and water in a natural draft hybrid cooling tower model(NDHCTs), both directly (wet section) and indirectly (dry section). The tower is filled with splash-style packing, and the warm water is spread throughout the building using sprayer nozzles. The influences of water flow rates, fill thickness, and air velocity on the cooling range, approach, cooling capacity, thermal efficiency of the cooling tower, water evaporation loss into the air stream and water loss percentage were explored in this study. The experimental were carried out with four different water flow rates, ranging from 7.5 to 12 (Lpm) litres per minute, and eight different air velocities, all while keeping a constant inlet water temperature and a zero (m/s) crosswind. Data has been gathered, and performance variables have been determined. The findings demonstrate that the cooling tower's efficacy increases when the water flow rate is low, and the cooling range increases with increasing air velocity and decreases with increasing water flow rate; for a 7.5 Lpm water flow rate and a 2.4 m/s air velocity, it expanded to 19.5 ℃. The cooling capacity increased to 23.2 kW for a water flow rate of 12 Lpm and an air velocity of 2.4 m/s.</p> </abstract>

Efficient Stochastic Model for Operational Availability Optimization of Cooling Tower Using Metaheuristic Algorithms

Metaheuristic algorithms are extensively utilized to find solutions and optimize complex industrial systems’ performance. In this paper, metaheuristic algorithms are utilized to predict the optimum value of the operational availability of a cooling tower in a steam turbine power plant. These techniques have some flaws like poor convergence speed, being stuck in local optima, and premature convergence. For this purpose, a novel efficient stochastic model is proposed for a cooling tower that is configured with six subsystems. The Markovian birth-death process is utilized to develop the Chapman-Kolmogorov differential-difference equations. All the random variables are statically independent, and repairs are perfect. Failure rates are exponentially distributed, while repair rates follow the arbitrary distribution. Steady-state availability (SSA) of the system is derived concerning various failure and repair rates. The sensitivity analysis of SSA is also performed to identify the most critical component. Further, system availability is optimized using genetic algorithm (GA) and particle swarm optimization (PSO) because they are found to be more suitable for such types of problems. It is revealed that the PSO outperforms GA in predicting the availability of cooling towers used in steam turbine power plants.

Heat and mass transfer performance and exergy performance evaluation of seawater cooling tower considering different inlet parameters

Cooling towers are important components within re-circulating cooling water systems. Due to a shortage of freshwater resources, seawater cooling towers are widely used both in manufacturing and everyday life. This paper researches the mechanical draft counterflow wet seawater cooling tower, and establishes and verifies a detailed thermal performance calculation model. Referring to the Second law of thermodynamics, the heat and mass transfer performance and exergy performance of the seawater cooling tower were studied. The effects of salinity, inlet air speed, and air wet-bulb temperature on the cooling efficiency, thermal efficiency, and exergy efficiency were analyzed. The results show that compared to the air wet-bulb temperature, changes in air speed have more influence on cooling and thermal efficiency under the study conditions. Moreover, the air wet-bulb temperature is the significant parameter affecting exergy efficiency. With an increase in salinity, the cooling, thermal, and exergy efficiency are about 2.40-8.25%, 1.06-3.09%, and 2.47-7.73% lower than that of freshwater, respectively, within an air speed of 3.1-3.6 m/s. With an increase in salinity, the cooling, thermal, and exergy efficiency are about 2.28-8.47%, 1.03-3.37%, and 2.44-7.99% lower than that of freshwater, respectively, within an air wet-bulb temperature of 25-27?. Through the exergy analysis of the seawater cooling tower, it is obvious that the heat and mass transfer performance and exergy performance can be improved by selecting the optimum operating conditions and appropriate packing specifications.

Research of Cooling Tower Filler Based on Radial Basic Function Artificial Neural Network (Rbf Ann)

Research of Cooling Tower Filler Based on Radial Basic Function Artificial Neural Network (Rbf Ann)

An Analytical and Numerical Solutions for the Thermal Analysis of a Mechanical Draft Wet Cooling Tower

An Analytical and Numerical Solutions for the Thermal Analysis of a Mechanical Draft Wet Cooling Tower

Development of an Icing Prediction Model for Water Vapor from Geothermal Power Plant Cooling Towers

Development of an Icing Prediction Model for Water Vapor from Geothermal Power Plant Cooling Towers

Influence of New Vertical Corrugated Packing on Thermal Performance of Cooling Tower

Influence of New Vertical Corrugated Packing on Thermal Performance of Cooling Tower

Fostering Engineering Laboratory Course Teaching by Embedding an Inquiry-Guided Learning Approach Using Computer-Aided Learning Packages: Evaluation of Learning Outcomes in a Cooling Tower Experiment in the Unit Operations Lab

A Computer-Aided Learning Package as Inquiry-Guided Learning (CALP/IGL) was implemented in a cooling tower experiment for 43 students enrolled in four sections of the Unit Operations Laboratory course in the chemical engineering program at Qatar University. The impact of this approach on the attainment of learning outcomes was evaluated. Results show that CALP/IGL helped improve the attainment level of course learning outcomes by ~35%. The skills improved were mainly those aiming for the students' ability to interpret and discuss the experimental data. The criteria for improvement were mainly the students' ability to explain the chart trends according to the relevant theoretical principles, leading to addressing misconceptual mistakes. It also helped mitigate educational logical fallacies and reduce the academic gap among students of different learning styles and capabilities.

Kinetic and Thermodynamic Studies of Ion Exchange Process in Removal of Ca2+ and Mg2+ from Cooling Tower Water using Amberlite IR 120 and Amberjet 1200

In this study, the thermodynamics and kinetics parameters of the ion exchange process in removing Ca2+ and Mg2+ from cooling tower water using Amberlite IR1200 and Amberjet were investigated. Thermodynamics and kinetics were studied by varying the amount of contact time (min), adsorbent (mL), temperature (K), concentration (mg/L) and pH of the solutions. The effectiveness of pecentage removal was found to rely on pH, as there was a significant increase of removal percentage Ca2+ and Mg2+ from pH of 3 to 6. The contact time was reached after 60 min on both resins. The correlation coefficients (R2) of Langmuir, Freundlich and Tempkin isotherms ranged from 0.92 to 1, suggesting that the experimental data best described the models. However, correlation coefficients (R2) for the D-R model range between 0.5 to 0.8, which means that experimental data does not fit the model well. Thermodynamic functions such as entropy (ΔSº), enthalpy (ΔHº) and change of free energy (ΔGº) were obtained from the gradient and intercepts of straight-line graphs. The positive values of ΔGº indicated that the adsorption is not spontaneous. Positive values of ΔHº were found, meaning the endothermic type of adsorption, which indicates the chances of physical adsorption. The correlation coefficient (R2) values of pseudo-first-order, pseudo-second-order and intraparticle models ranged from 0.89 to 1 on both metals. This observation indicates that pseudo-first-order, pseudo-second-order and intraparticle diffusion models best describe the experimental data in removing Ca2+ and Mg2+ from cooling tower water.

Research on Innovative Design of Industrial Heritage's Regeneration through a Combination of Extenics and BIM: TangShan Cooling Tower as an Example

In the process of urban development, a large number of industrial heritages are in needs of being renovated as a result of the failure of meeting new needs. However, there has not yet formed an innovative and sustainable update design process. Based on the analysis of the problems existing in the renewal and reconstruction of industrial heritages, this paper, hereinafter, will establish an innovative design system by way of introducing extenics and BIM and combining the formalized and innovative advantages of extenics and the characteristics of BIM: information storage, processing and visual programming. In combination with the design of practical cases, this essay conducted the system, to verify its rationality and effectiveness; to discover limitations in its operation, and as the ultimate purpose, to propose directions for further research.