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Background: Cooling towers (CTs) are crucial to myriad industrial processes, supporting thermal exchange between fluids in heat exchangers using water from lakes and rivers as coolant. However, CT water can sometimes introduce microbial contaminants that adhere to and colonize various surfaces within the CT system. These microorganisms can form biofilms, significantly hindering the system's thermal exchange efficiency. Current treatment strategies employ oxidizing biocides to prevent microbial growth. However, despite their affordability, they do not eliminate biofilms effectively and can lead to corrosive damage within the system. Herein, we aim to devise an anti-biofilm strategy utilizing hydrolytic enzymes (such as α-amylase, glucoamylase, pectin-lyase, cellulase, protease, and DNase) alongside antibiotics (including meropenem, ciprofloxacin, gentamicin, erythromycin, chloramphenicol, and ceftriaxone) to combat microbial growth and biofilm formation in cooling systems. Results: All enzymes reduced the development of the biofilms significantly compared to controls (p < 0.05). The polysaccharidases exhibited biomass reduction of 90%, except for pectin-lyase (80%), followed by DNAse and protease at 43% and 49%, respectively. The antibiotics reduced the biofilms of 70% of isolates in concentration of > 2 mg/mL. The minimal biofilm eradication concentration (MBEC) lower than 1 mg/mL was detected for some 7-day-old sessile isolates. The enzymes and antibiotics were also used in combination against biofilms using the modified Chequerboard method. We found six synergistic combinations, with Fractional inhibitory concentrations (FIC) < 0.5, out of the ten tested. In the presence of the enzymatic mixture, MBECs presented a significant decrease (p < 0.05), at least 4-fold for antibiotics and 32-fold for enzymes. Moreover, we characterized high molecular weight (> 12 kDa) exopolysaccharides (EPS) from biofilms of ten isolates, and glycosyl composition analysis indicated a high frequency of glucose, mannose, erythrose, arabinose, and idose across isolates EPS contrasting with rhamnose, allose, and those carbohydrates, which were detected in only one isolate. Conclusion: The synergistic approach of combining enzymes with antibiotics emerges as a highly effective and innovative strategy for anti-biofilm intervention, highlighting its potential to enhance biofilm management practices. [ABSTRACT FROM AUTHOR]

In industrial processes involving both heat and mass transfer, the enthalpy or total energy difference, not the temperature difference, is a more comprehensive driving-force potential for the design of heat exchanger systems, such as cooling towers. However, current enthalpy methods based on the Merkel integral require numerical integration with implied linear distributions of water temperature. If the cooling range of the cooling tower is relatively small, the outcome of the integration may carry little error. However, for a large cooling range and a substantially increased temperature, the error involved may be significant. Like log-mean temperature difference, a log-mean enthalpy difference method may require only the inlet and outlet conditions without prior knowledge of the enthalpy distributions of the fluids within the heat exchanger. The known Berman's enthalpy difference method requires correction factors and was derived based on the linearization of the interfacial enthalpy and the enthalpy difference between the interfacial moist air and the bulk moist air without underlying interpretation to demonstrate that the method could be broadly used. In this paper, an equivalent enthalpy model is proposed, and the log-mean enthalpy difference is derived without retaining model assumptions. The derived method is compared with some results of Merkel's method from literature with excellent agreement. Thus, the work in this paper would open up the possibility for broad uses of the log-mean enthalpy difference method for many industrial processes involving both heat and mass transfer. [ABSTRACT FROM AUTHOR]

This study deals with an experimental investigation of the thermal performance of a prototype mechanical wet cooling tower with a counter flow arrangement. Different volume concentrations ranging from 0.18 to 0.50 vol.% of stable Al oxide (Al2O3), Zn oxide (ZnO), and Ti oxide (Ti2O3) nanoparticles of 80, 35, and 70 nm diameter were considered. Water was taken as a base fluid, and the experiment was carried out at 60, 70, and 80 ℃, respectively, in laboratory conditions. The study revealed that an increase in the volume concentration of the nanofluids increased the cooling range, cooling efficiency, convective heat transfer coefficient, tower characteristic called number of transfer unit (NTU), and effectiveness of the cooling tower compared with water at the same mass flow rate and inlet temperature. However, increasing the volume concentration increased the viscosity of the nanofluids, leading to an increase in friction factor. For instance, for 0.18% volume concentration of ZnO, at an inlet water temperature of 66.4 ℃ and water/air (L/G) flow ratio of 1.93, the cooling range increased by 3.62%, cooling efficiency increased by 33.3%, and NTU increased by 50.5% compared with fresh water (FW). [ABSTRACT FROM AUTHOR]

The Behavior of Cement Portland Cooling Tower was evaluated numerically and experimentally. The three-dimensional simultaneous governing equations of the fluid flow, heat transfer and mass transfer were discretized and solved numerically, and the result of simulation were compared with measured data from the cement factory and with the available published result on the internet. Solid software was used as numerical software tool to predict the performance characteristics of cooling tower in Portland cement factory such as the velocity, temperature, stress and strain were simulated and compared with compute experiment. Experimentally the temperature, and pressure of gaseous and its emission across the cooling tower in White Portland cement factory were measured. The agreement seems acceptable between the numerical and experimental results. [ABSTRACT FROM AUTHOR]

A hybrid cooling tower, which is a promising type of coolers, can be used successfully to cool the circulating water of industrial enterprises taking into account the modern requirements for energy efficiency, resource saving, and environmental friendliness. A hybrid cooling tower design has been developed including a sprinkler made of inclined corrugated contact elements and an internal finned tubular radiator. The purpose of the work is to experimentally determine the volumetric coefficients of heat and mass emission in the developed hybrid cooling tower for cooling circulating water. A diagram of an experimental installation of a cooling tower with hybrid cooling system is presented and described. Graphic dependences were constructed for the volumetric coefficients of mass emission and heat emission on the average flow rate of cooling air at various wetting mass densities. A dimensionless equation has been obtained for determining the volumetric coefficients of mass emission in a hybrid cooling tower with transverse finning of radiator pipes. A comparison of volumetric coefficients of mass emission for the developed cooling tower with other water-cooling devices showed the potential of its usage for cooling circulating water, especially at high ratios of gas and liquid phase loads. [ABSTRACT FROM AUTHOR]

The number of XLPE cables being used near or beyond their design life is increasing. The importance of timely cable replacement is necessary. Therefore, research is actively being conducted using VLF Tan δ diagnostic technology to assess the insulation condition of cables. Present studies lack in measuring and analyzing the VLF Tan δ of service-aged XLPE cables. Additionally, there is a research gap considering the operating environment. Therefore, it is needed to diagnose and analyze the insulation condition of the same service-aged cable when it is operated in a different environment. This paper assesses and analyzes the insulation condition of cables installed in the BFP, cooling tower, and deaerator booster pump of a combined heat and power plant. Each cable was evaluated by measuring the VLF Tan δ, the dielectric breakdown test of the cable, and the tensile strength, elongation at break, crystallinity, and dielectric strength of the XLPE specimens. Additionally, the correlation between the VLF Tan δ and other characteristics was also analyzed. It was found that degradation progressed in the order of the BFP, the cooling tower, and the deaerator booster pump. Therefore, it was confirmed that even for the same cable, deterioration varies depending on the installation location. [ABSTRACT FROM AUTHOR]

A total of 17 Legionnaires' disease cases were identified in an outbreak in a western town in New York. The cases had symptom onset dates ranging from August 1, 2019, to July 1, 2021. Staff from the New York State Department of Health and Chemung County Health Department employed numerous environmental investigation techniques. Environmental health program staff collected 74 environmental samples, including samples from cooling towers, residences, and a wastewater treatment plant. Wind direction was analyzed to determine the potential for the dispersion of aerosolized Legionella. In total, five cases were found to be genetically related by whole genome sequencing. Further testing revealed that isolates recovered from a cooling tower at an industrial facility were genetically related to four of the 2019 cases. Excessive iron was found in the tower and might have suppressed the oxidizing biocide residual and interfered with the evaluation of routine culture and other testing methods. In 2021, clinical and environmental samples from a private hot tub were found to be genetically related to the four matching cases and cooling tower samples recovered in 2019. [ABSTRACT FROM AUTHOR]

This work presents a novel sustainable approach to producing desalinated water (W des), green hydrogen (G H 2 ) and electrical energy (E elc) using Hybrid Solar Chimney Power Plant (HSCPP) coupled with a water-splitting (Wat Sp) process. The HSCPP consists of a collector, absorber, chimney, bidirectional turbine outfitted with a seawater pool, and water electrolysis (Wat elc) cell. The HSCPP harnesses solar energy to heat the air under the collector creating air movement within the structure, passing the bidirectional turbine, and producing E elc. Sprinklers were fitted within the structure to operate the HSCPP as a cooling tower (CT) in the absence of solar radiation (Sol irr). The Wat elc cell directly uses the produced E elc for the production of Hydrogen (P H 2 ) and oxygen (P O 2 ), while the condensed water at the chimney's inner walls was also collected as W des. Results revealed that the continuous operation of the HSCPP has an average annual E elc of 633 ± 10 MWh that could be efficiently used to generate 21,653 kg of G R H 2 , 173,244 kg of O 2 as well as 190,863 tons of W des. The overall efficiency of the HSCPP for the P H 2 was found to be 18.5 % , which is higher than Solar PV (max∼ 6%) and geothermal Rankine (max∼ 15%). These high efficiencies rank this technology as competitive with other renewable hydrogen production technologies. In conclusion, HSCPP has a promising future as a novel and sustainable solar tower technology to produce hydrogen. [Display omitted] • A novel solar-driven system for the production of green Hydrogen is proposed. • The proposed system generates hydrogen, electricity and desalinated water. • The integrated system achieved a solar-to-hydrogen conversion efficiency of 18.5%. • The HSCPP produced of 633 MWh, 21,653 k g H 2 , 173,244 k g O 2 and 190,863 tons H 2 O. [ABSTRACT FROM AUTHOR]

Optimization plays an important role in scientific and engineering research. This paper presents the effects of using the catenoidal shape to design the structure of a chimney cooling tower. The paper compares some geometrical variations of the catenoid with the reference existing hyperboloidal structure. It also compares internal forces, deformation and stability of the catenoidal structure. The comparison shows some predominance of the catenoid over the popular hyperboloid structure of the shell. The paper attempts to find an optimal shape of the cooling tower in order to reduce the amount of material and labor. The paper utilizes engineering tools and the designing process for chimney cooling towers. [ABSTRACT FROM AUTHOR]

This research describes a hybrid solar desalination system that includes a humidification-dehumidification unit as well as a solar still unit. The current system is being studied numerically. A one-dimensional model of the important heat and mass exchanges, as well as the flow field, was built using the finite difference method. Freshwater productivity is calculated under various operating and weather conditions. The model has been modified to investigate the steady-state behavior of the system components. Four major parameters that have a significant impact on system water production are investigated: the feed flow rate of cooling water through the dehumidifier unit, the airflow rate, and the number and height of packing columns. According to the results, the proposed hybrid desalination system provides appropriate operational compatibility between HDH technology and solar energy. The system can provide a daily production of up to 35 liters per day. Increasing the number of packing columns results in a higher increase in fresh water productivity than increasing the height of the packing columns. The optimal air flow rate at a constant saline-water flow rate is obtained. For high airflow rates, the packing column height doesn't significantly affect the daily water production. System performance is investigated by four main parameters: gained output ratio (GOR), humidifier efficiency, exergy efficiency, and system efficiency. The system efficiency reached about 65% and the GOR reached 3.1. The humidifier's efficiency varied between 50% and 75%. The maximum exergy efficiency reached about 5.2%. [ABSTRACT FROM AUTHOR]

The appearance and development of new construction materials, technology and accurate geodetic instruments have led to the necessity of their inevitable use in the health monitoring, maintenance, and restoration of civil structures and special structures such as high-rise cooling towers. This paper presents an accurate practical and analytical method for determining the structural deformation and axis inclination of high rise cooling towers using terrestrial laser scanner (TLS) observations through the projection of tower surface points coordinates on a vertical plane. Four cooling towers in El-Mahla El-Kubra city, Egypt are observed and studied. Two of them with height 56 m, and the others were 36 m height. The studied four towers have different cross-section diameters along the tower height. Each tower has a cone shape with a curved wall. The equation of the tower wall is determined using TLS observations and least squares adjustment techniques. The equations of cone projection with a curved wall are derived and presented in this paper. From TLS observations, the radii and accuracy of each 2 m tower height are determined with center coordinates, and then the inclination of the tower axis is calculated and drawn. From the results of TLS observations, data processing, and analysis using the suggested techniques, it is deduced that there is a deformation in tower walls with small values. The specified technique for observations collection and TLS data analysis through projection on a vertical plane is significant and valuable for determining the structural deformation of circular high rise buildings and towers. From the results, there are obvious deformation values in some cooling towers, so maintenance work must be included. The towers also must be checked and monitored several times at brief intervals. [ABSTRACT FROM AUTHOR]

There is a height drop in the rain area of the circulating cooling water in mechanical ventilation circulating cooling towers, resulting in the ineffective use of gravitational potential energy. High-level water collection is an effective way to reduce the energy consumption of the cooling tower. Based on this, aiming to solve the gravity energy waste problem of circulating water in the cooling tower of a steel plant, this paper innovatively puts forward the high-level water tank to utilize the energy-saving transformation technology of turbine power generation and pump power saving. Additionally, this paper explores the energy-saving effects of the two methods under different height drops. The results show that the maximum utilizable rain area height of the cooling tower is 5 m, while the annual electric energy output of turbine technology can reach 4.704 million kW·h. The high water collection technology can reduce pump power consumption and save up to 7.35 million kW·h per year of electric energy, maintaining a more significant energy-saving ability compared with the turbine power generation technology. In terms of performance, the design of a high-level water tank is to help eliminate rain areas and improve the heat exchange efficiency of water and gas, so that the water temperature of the outgoing tower is 0.13 °C lower than that of the conventional cooling tower. Meanwhile, the ventilation resistance in the rain area is weakened, the resistance coefficient can be reduced by about 40–50%, and the noise can be reduced by about 10 dB (A) under the action of the water collection device. According to the economic evaluation, the total cost of turbine power generation technology is 0.563 million dollars and the total cost of high-level water collection technology is 0.446 million dollars. The cost can be realized within two years, but the high-level water collection technology avoids additional pump maintenance costs and has better economy. This study provides a theoretical basis for the transformation and optimization design of mechanical ventilation cooling towers, and has important reference value. [ABSTRACT FROM AUTHOR]

• Hydrodynamics in cooling tower packing has been numerically simulated. • Main local and system scale hydrodynamic parameters have been obtained. • Packing wetting rate and film thickness increase with water flow inlet increase. • A correlation has been proposed for interfacial area to evaluate transfer phenomena. Wet cooling towers are used in many industrial processes but hydrodynamic behaviour of air-water counter flows in towers packing remains unknown. Hydrodynamics is directly linked with main operating issues (e.g. packing fouling reducing cooling efficiency). The objective of this work is to use Computational Fluid Dynamics (CFD) simulations to characterize local hydrodynamic parameters such as water film thickness, velocity or wall shear stress and system scale parameters such as wetting rate or interfacial area. After a theoretical study of fluid mechanics, Volume of Fluid (VOF) simulations, with dedicated models for air/water interface capture and solid/liquid contact angle, successfully reproduced water falling films on packing surface. Simulations allowed the calculation of main water flow local and system parameters. The results have pointed out trends of increasing liquid film thicknesses and wetting rates with increasing water flowrate in agreement with experimental observations. A correlation of the interfacial area has been proposed as a function of the hydrodynamic adimensional numbers to characterize transfer phenomena in the considered packing. [ABSTRACT FROM AUTHOR]

Corroded points can act as stress concentrators, usually resulting in the component failure at fewer cycles than was initially projected. Aerators are widely used in waste treatment units for chemical and biological control. Due to the chemically aggressive environment to which these components are subjected, they usually fail due to corrosion in one or more components. Cooling towers are one of the most applied equipment for temperature control in industrial processes. Due to generally hostile environments and operating conditions, this equipment is subject to failures which almost always lead to system imbalance followed by the catastrophic failure of the component. This work investigates the synergic effect of corrosion and fatigue in two separate case studies. In the first, the wear of the mixing shaft of an aerator was investigated. It was observed that the root cause of wear was the corrosion of the dissimilar welded joints in the mixing blades, which suffered the sensitization phenomenon. This sensitization led to the formation of accentuated corrosion pits, which concentrated stresses and led to the failure of the welded joint. After the joint failure, the component was left in an unbalanced state, which resulted in severe wear on the mixer shaft of the aerator. In the second, the failure of a cooling tower fan shaft fracture was evaluated, with the fractured component being compared to an intact one. As means of analysis were employed: metallographic tests on macroscopic and microscopic scales, tensile, chemical composition, hardness tests, and fractography. The results indicated the component failure due to fatigue under low amplitude loading, with corrosion pits as stress intensifiers. [ABSTRACT FROM AUTHOR]

The filler is the core component of the cooling tower, filler performance refers to both its thermal and flow resistance characteristics, which use empirical formulas of tower characteristic N, volumetric mass transfer coefficient βxv, and pressure drop ΔP obtained through experimentation under specific conditions. However, the performance equations for identical countercurrent fillers can vary at different heights or seawater concentrations. Linear interpolation is the conventional method for obtaining the filler performance under different conditions, but its uncertainty limits the application. This paper explores the use of the radial basis function artificial neural network (RBF ANN) to analyze filler performance based on existing performance equations. The data set is generated by the filler performance equations. The results demonstrate that RBF ANN has a preferable prediction effect with high correlation (the determination coefficient R2 > 0.99) and prediction accuracy (the proportion of relative error within 10% N10 > 90%). Furthermore, the predicted results are consistent with the experimental results of the filler performance. Therefore, RBF ANN can accurately predict filler performance at varying heights and seawater concentrations, making it universal and providing a basis for cooling tower design. [ABSTRACT FROM AUTHOR]

A model of motion of a two-phase continuous medium in a cooling tower is presented. The medium consists of water particles and a steam/air mixture. The composition of the mixture changes, as a result of which chemical work is performed, which was not taken into account in early models. Comparison with earlier results reveals a strong influence of the chemical work on the results of modeling, with the general mathematical structure of the model remaining unchanged — in the case of free convection, it is necessary to solve an eigenvalue boundary-value problem with a continuous spectrum, where the eigenvalue is the air flow at the cooling tower inlet, and the minimum flow value corresponds to free convection. [ABSTRACT FROM AUTHOR]

Improving the environmental performance and energy efficiency of cooling towers requires systematic evaluation. However, methodological challenges emerge when applying typical environmental assessment methods to cooling towers. Hence, this paper compares the methods, analyzes their strengths and weaknesses, and proposes adaptions for evaluating cooling towers. As a case study, we applied five methods for assessing the wet cooling system of the high‐performance data center in Stuttgart. These are material flow analysis (MFA), life cycle inventory, life cycle assessment (LCA), exergy analysis, and life cycle exergy analysis (LCEA). The comparison highlights that the LCA provides the most comprehensive environmental evaluation of cooling systems by considering several environmental impact dimensions. In the case of the wet cooling tower, however, electricity and water consumption cause more than 97% of the environmental impacts in all considered impact categories. Therefore, MFA containing energy flows suffices in many cases. Using exergy efficiency is controversially debated because exergy destruction is part of the technical principle applied in cooling towers and, therefore, difficult to interpret. The LCEA appears inappropriate because construction and disposal barely affect the exergy balance and are associated with transiting exergy. The method comparison demonstrates the need for further methodological development, such as dynamic extensions or the efficiency definition of cooling towers. The paper highlights that the methodological needs depend on the specific application. [ABSTRACT FROM AUTHOR]

Optimized concepts for the deconstruction of natural draught cooling towers by blasting The deconstruction of natural draught cooling towers represents an essential part in the course of the conversion of old power plant sites. For monetary reasons in combination with reasons of sustainability, which are particularly reflected in the reusability of the site area and the recycling of the resource reinforced concrete, an immediate deconstruction of the natural draught cooling towers after the end of operation is recommended in most cases. In addition to the established state of the art, the article shows potentials for the further development of concepts for the deconstruction of natural draught cooling towers by blasting. Complex numerical simulations nowadays offer the possibility of precise simulations of both the structural stability for temporary, weakened construction stages and the collapse behaviour of reinforced concrete structures in the event of blasting. The key aspect is safety in various facets, which must also be considered and guaranteed for adjacent buildings in the immediate neighbourhood in particular. The new deconstruction concepts presented, for which no practical experience is available at this time, are compared with the established concepts with regard to the aspects of structural stability, collapse safety, vibration prognosis, necessary safety measures, effects on the environment, workload and costs. [ABSTRACT FROM AUTHOR]

Cooling towers have been linked to Legionnaires’ disease cases and outbreaks. Legionella pneumophila results (from a culture-based method) are presented for 557 cooling towers across the City of Vancouver, Canada for 2021. Results of 10 CFU/mL or greater (defined as exceedances) were reported for 30 cooling towers (5.4%), including six .1,000 CFU/mL, and L. pneumophila serogroup 1 (sg1) was identified in 17 of these cooling towers (out of 28 with serogroup-level analysis). The data indicate highly localised Legionella issues, with exceedances concentrated within 16 facilities, including two hospitals. In the 3 months preceding each cooling tower exceedance, the nearest municipal water sampling station had a free chlorine residual of at least 0.46 mg/L and a temperature of,20 °C. There was not a statistically significant correlation between the L. pneumophila concentration of a cooling tower in exceedance and the municipal water free chlorine residual, temperature, pH, turbidity or conductivity. There was a statistically significant negative correlation between the concentrations of L. pneumophila sg1 and other L. pneumophila serogroups in cooling towers. This unique dataset underscores the pivotal role of building owners and managers in preventing the growth of Legionella bacteria and the value of regulations to verify operations and maintenance practices. [ABSTRACT FROM AUTHOR]

Cooling towers are essentially large boxes designed to maximize the evaporation of water. The inlet water temperature and water to air mass flow rate ratio (L/G) significantly affect the performance of the cooling tower. The number of a transfer unit (NTU), Merkel number (Me), Lewis number (Le), and efficiency of the cooling tower define the performance of the forced cooling tower. In this research paper, different inlet water temperatures ranging from 28 °C to 42 °C and (L/G) ranging from 0.5, 1, and 1.5 were used to investigate the performance of the forced cooling tower. Mathematical modeling equations were used to calculate NTU, Me, Le, and efficiency at different inlet water temperatures and (L/G). Engineering equation solver (EES) software was used to solve these mathematical modeling equations. Further, an experimental investigation was carried to find forced cooling tower performance at different inlet water temperatures and (L/G), and results were compared with the theoretical results. The results revealed that increasing the inlet water temperature, NTU, Me, Le, and efficiency increased and were directly related to each other. Further, NTU and efficiency were increased by increasing (L/G). At the same time, the Me and Le reduced with (L/G). Finally, an acceptable and better agreement has been obtained between experimental and theoretical results. Based on obtained results, it has been concluded that higher values of inlet water temperature and (L/G) provided the higher performance of the forced cooling tower. [ABSTRACT FROM AUTHOR]

Overheating of photovoltaic (PV) panels decreases their efficiency and lifetime, and subsequently increases the levelized cost of energy (LCOE). Passive PV cooling would enhance the PV operational stability and durability. The cooling tower (CT) technology offers an attractive approach for zero-cost capability. In this work, we developed and customized a CT specific for passive PV cooling. Since the dense downdrafted cooled air gained high velocity, a turbine was installed at the bottom of the CT for power production. At the height's ambient temperature, the CT cooled the air from 50 °C down to 30 °C. The cooled air at 30 °C has enough capacity to cool the PV panels. This cooling capacity improved the average annual efficiency of the PV panels by 6.83%. The design specifications of the CT have the highest performance, with the maximum radius of PV area of panels that can be cooled at 50 m. Furthermore, the current design could operate during the night for power production with minimum operational cost. [ABSTRACT FROM AUTHOR]

A mathematical formulation of the problem of finding the optimal size of water droplets and their initial velocity with restrictions on the cooled water temperature and water losses in the form of steam is given. In the case of free convection, such an optimization problem also becomes a boundary-value eigenvalue problem with a continuous spectrum, where the eigenvalue is the air flow at the cooling tower inlet. To free convection there corresponds the minimum flow value. The solutions are obtained for the initial temperature of the cooled water (70°C) sprayed in the tower with 1.8 kg·m–2·s–1. Attention is drawn to the difficulty of assessing the loss of water in the form of microscopic droplets. [ABSTRACT FROM AUTHOR]

Cooling towers are essentially large boxes designed to maximize the evaporation of water. The inlet water temperature and water to air mass flow rate ratio (L/G) significantly affect the performance of the cooling tower. The number of a transfer unit (NTU), Merkel number (Me), Lewis number (Le), and efficiency of the cooling tower define the performance of the forced cooling tower. In this research paper, different inlet water temperatures ranging from 28 °C to 42 °C and (L/G) ranging from 0.5, 1, and 1.5 were used to investigate the performance of the forced cooling tower. Mathematical modeling equations were used to calculate NTU, Me, Le, and efficiency at different inlet water temperatures and (L/G). Engineering equation solver (EES) software was used to solve these mathematical modeling equations. Further, an experimental investigation was carried to find forced cooling tower performance at different inlet water temperatures and (L/G), and results were compared with the theoretical results. The results revealed that increasing the inlet water temperature, NTU, Me, Le, and efficiency increased and were directly related to each other. Further, NTU and efficiency were increased by increasing (L/G). At the same time, the Me and Le reduced with (L/G). Finally, an acceptable and better agreement has been obtained between experimental and theoretical results. Based on obtained results, it has been concluded that higher values of inlet water temperature and (L/G) provided the higher performance of the forced cooling tower. [ABSTRACT FROM AUTHOR]

With advancement of dry-air cooling technology, it has become feasible to use steel reticulated shell structures in design and construction of industrial cooling towers. Steel reticulated shell cooling towers (SRSCTs) with light weight, high strength, and rapid construction have development potential. Wind-induced collapse accidents in cooling towers frequently occur, characterized by pronounced nonlinear behavior involving significant deformation and material failure. Nevertheless, current stability and collapse analyses of cooling towers based on linear theory and elastic deformation are inadequate and unsafe. Thus, the wind-resistant stability of SRSCTs must be evaluated considering their inherent high flexibility and low damping levels. Considering a 220 m high hyperbolic SRSCT as a case study, a wind-induced collapse FEM simulation and analysis were performed. The average and fluctuating wind loads were measured in a reduced-scale model during wind tunnel tests and used as the time-variant wind pressure in a structural finite-element model. The dynamic performance and buckling collapse analyses of the cooling tower were conducted considering geometric and material nonlinearities. The entire wind-induced failure process of the SRSCT in extreme winds was systematically investigated. The weaknesses in the structural stiffness and the failure process were quantified, with five failure stages and four failure modes. The failure stages included linear elasticity, local member failure, local regional failure, overall structural failure, and collapse. The failure modes included circumferential plastic buckling zone failure, windward buckling failure of the shell, crosswind failure of the stiffening ring (hinged curved-beam mechanism), and windward failure of the stiffening ring (triangular arch-like mechanism). This study confirms that development of plastic buckling zones and formation of plastic hinges, considering geometric and material nonlinearity, are the dominant factor in wind-induced failure and collapse of SRSCTs. • Time-variant wind pressures were obtained based on the rigid pressure measurement tests. • Entire wind-induced collapse process of a 220 m high steel reticulated shell cooling tower was simulated. • Development of plastic buckling and degradation of structural stiffness were analyzed. • Wind-induced failure stages, modes, and mechanisms of the steel cooling tower were summarized and revealed. [ABSTRACT FROM AUTHOR]

• Develop a inclined folding wave packing. • Contrast analysis of inclined folding wave and ramp packing performance. • Numerical simulation studies on different operating parameters. • Fitting the empirical equation of thermal resistance. Improve the heat transfer performance of cooling tower packing in the field of energy saving and environmental protection is of great significance, this study proposes a kind of inclined folding wave packing, using experimental research and numerical calculations combined method to study the heat and mass transfer characteristics of inclined folding wave packing, the results show that: inlet wind speed rises, the cooling tower approximation reduced from 4.38 °C to 2.78 °C; when the gas to water mass ratio increases from 0.322 to 1.019, the cooling number from 1.115 to 1.754; when the gas to water mass ratio of 0.54, the height of the packing from 0.915 m to 1.830 m, the cooling number from 1.15 to 1.64, the height of the packing to enhance the channel of the gas-liquid heat transfer effect. Compared with the traditional ramp packing, the cooling efficiency of the developed inclined folded wave packing is improved by 15.32 %. Combined with the actual engineering test found that the packing height can be increased to reduce gas to water mass ratio and air volume requirements, up to 28 % of the air volume can be saved. The motor output power of 1.830 m high inclined folding wave packing in actual operation is 0.268 kW, compared with 0.915 m high inclined folding wave packing, the difference in energy consumption is 0.246 kW. Inclined folding wave packing can not only improve the overall performance of the cooling tower, but also significantly reduce energy consumption, which can guide the engineering practice. [ABSTRACT FROM AUTHOR]

• Simulated seismic response of a reinforced concrete cooling tower using SAP2000. • Analyzed the impact of different column support systems on seismic behavior. • Identified areas of excessive stress, deformation, and vulnerable components. • Insights guide improvements for seismic resistance and structural integrity. The seismic behavior analysis of a reinforced concrete cooling tower using SAP2000 aims to simulate and evaluate the structure's response to seismic loads, both from near and far movements. This process begins with the creation of a numerical model that incorporates the tower's geometry, construction materials, and anticipated seismic loads and constraints. The cooling tower is supported by I-type and Ʌ-type columns. Relevant comparisons of the dynamic response of the structural system have been made at the base level (where the columns meet the shell), throat level, and at the top of the tower. The results from these analyses enhance our understanding of the cooling tower's seismic behavior, highlighting areas of excessive stress, potential deformations, and components vulnerable to damage during an earthquake. This information is vital for informing structural improvements that enhance the seismic resistance of the cooling tower and ensure its stability during seismic events, regardless of their proximity. [ABSTRACT FROM AUTHOR]

• Aerodynamic characteristics and load distributions of super large cooling towers (SLCTs) exposed to tornados were obtained. • Local stability and structural reinforcements of the SLCTs exposed to the tornado-like vortices was investigated. • Effects of swirl ratios, SLCT layouts, and the central distances between the SLCTs and the tornado were investigated. • Various interference criteria at aerodynamic loading and structural reinforcement aspects were contrastive analyzed. • Time-variant dynamic reinforcement ratio is more reasonable for evaluating tornado-induced interference effects on SLCTs. A comprehensive investigation was conducted aiming at the interference effects on wind pressure distribution, aerodynamics characteristics, structural stability and reinforcement areas of super large twin cooling towers exposed to tornado-like vortices, and the effects of swirl ratios of tornados, grouped tower layouts, and relative central distances between the towers and the tornado were analysed based on a tornado-like vortex simulator. Two types of rigid model wind tunnel experiments were constructed for base forces and wind pressure distribution measurements. The experimental results demonstrate that the interference effects on base forces and local wind pressures are significantly influenced by the swirl ratios, central distances, and grouped tower layouts, etc. Moreover, the layout with a tornado located on the side of tandem twin cooling towers (along with the tornado translation direction being perpendicular to the central axis of the tandem combined twin cooling towers) is the most unfavourable, resulting in obvious amplification effects on base forces and local wind pressures compared with an isolated tower, and the maximum of interference factors (IFs) is 1.68 and 1.41 for the along-wind total wind force coefficient and minimal net mean pressure coefficient respectively. Subsequently, local stability indices and time-variant dynamic reinforcement envelopes were selected as the other evaluation criteria for estimating the interference effects on the cooling towers exposed to the tornado-like vortices, and the interference effects result in enlargements of the structural responses with the maximal IF of 1.36 for the inside meridional reinforcement. Finally, the various interference criteria at aerodynamic loading and structural reinforcement aspects were contrastive analysed, showing that the criterion of time-variant dynamic reinforcement area envelopes is a more reasonable criterion for evaluating the interference effects on the super large cooling towers exposed to the tornado-like vortices. This investigation aims to contribute to a better understanding of the wind-related effects of the cooling towers exposed to extreme non-synoptic winds, particularly tornadic vortex impacts. [ABSTRACT FROM AUTHOR]

A cooling tower is an important guarantee for the proper operation of a solar system. To ensure proper operation of the system and to maintain high-efficiency points, the cooling tower must operate year-round. However, freezing is a common problem that degrades the performance of cooling towers in winter. For example, the air inlet forms hanging ice, which clogs the air path, and the coil in closed cooling towers freezes and cracks, leading to water leakage in the internal circulation. This has become an intractable problem that affects the safety and performance of cooling systems in winter. To address this problem, three methods of freeze protection for cooling towers are studied: (a) the dry and wet mixing operation method—the method of selecting heat exchangers under dry operation at different environments and inlet water temperatures is presented. The numerical experiment shows that the dry and wet mixing operation method can effectively avoid ice hanging on the air inlet. (b) The engineering plastic capillary mats method—its freeze protection characteristics, thermal performance, and economics are studied, and the experiment result is that polyethylene (PE) can meet the demands of freeze protection. (c) The antifreeze fluid method—the cooling capacity of the closed cooling towers with different concentrations of glycol antifreeze fluid is numerically studied by analyzing the heat transfer coefficient ratio, the air volume ratio, the heat dissipation ratio, and the flow rate ratio. The addition of glycol will reduce the cooling capacity of the closed cooling tower. [ABSTRACT FROM AUTHOR]

This research work deals with the performance of high-density polyethylene sheets arranged in splash used as a fill for a cooling tower. “A forced-draught counterflow cooling tower” of 400 mm × 400 mm cross-sectional area and 1.7m in height was built. The fill has been studied theoretically and experimentally. Air rates of 0.6, 1.2, and 1.8 kg/s.m2 were utilized with water flow rates within the range of 1 to 1.6 kg/s.m² . The overall volumetric heat transfer coefficient, volumetric mass transfer coefficient (Mt), and the tower characteristics (Mt/L) are shown to be functions of the air and water flow rates concurrently. Four available input parameters were inlet water temperature, airflow rate, water flow rate, and full height. A computer program was prepared to perform numerical analysis for reducing data sets obtained from the plant. In addition, analysis was carried out for evaluating the volumetric heat and mass transfer coefficients along with the performance coefficient. [ABSTRACT FROM AUTHOR]

Uncertainties due to maldistribution in the operation of packed columns are one of the major issues in column design. Thus, thorough knowledge of the liquid distribution and the mass transfer processes within the packed bed is necessary. Models able to predict maldistribution are crucial for avoiding extensive experimental investigations. In the present study, the TUM-WelChem cell model is expanded by the simulation of heat and mass transfer in a packed column operated as a cooling tower. The simulation approach is based on experimental data obtained at the Technical University of Munich using a Ø0.634 m random packed column. Temperature profiles and global outlet values of liquid and gas temperatures along with the humidities are evaluated and discussed for the Hiflow® ring 50–6 polypropylene. The presented study provides insight into the applicability of the heat and mass transfer calculation by validating the simulation results with experimental data. [Display omitted] • Simulation of heat and mass transfer in a random packed column using a cell model. • Usage of the TUM-WelChem cell model as basis for liquid distribution. • Sequential and simultaneous calculation of the heat and mass transfer phenomena. • Bayesian optimization for correlations for heat and mass transfer coefficients. • Comparison of simulated temperature profiles and outlet values with experiments. [ABSTRACT FROM AUTHOR]

The paper focuses on water losses in the turbine condenser cooling system of the 905 MW power unit in Opole Power Plant (Opole Poland). The evaporative and drift losses are determined for various operating and atmospheric conditions. The drift loss is found to be 0.125–0.375% of the cooling water flux and some increase in this loss is noticed with increase in unit power and ambient temperature. The studies have shown that the presence of wind increases the total water loss related to the power generated by the power unit. This effect is analysed for selected constant air temperature values Tamb. The increase of the cooling water loss stream, related to the power of the unit, is at the level of 14.8% for Tamb equal to 7 °C, 23% for 15 °C, and approximately 10% at 22 °C. These increases are related to the level of losses in almost no wind conditions. It is investigated how the change in the cooling water flux affects the power unit operation and the amount of water loss. For the power unit under consideration, the reduction of the cooling water flux from 80,000 to 60,000 ton/h raises the temperature of water behind the condenser and lowers the temperature of the cooled water tw2 within the range of 0.75–1.5 °C, depending on the unit power and the ambient temperature. Reducing the cooling water flux in the analysed range results in an increase in condenser vapour pressure, within 0.5 kPa at Tamb = 25 °C. This increase is lower at lower ambient temperatures. Within the range of variations analysed, the effect of cooling water flux on evaporative losses is negligibly small. The increase in condenser steam pressure significantly affects the power generated by the turbine generator unit. The calculations show that it is possible to optimize the size of the cooling water flux for the analysed power unit and condenser cooling system. This optimization would allow (within a limited range of load variability) an increase in the net power generated by the power unit. [ABSTRACT FROM AUTHOR]

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°C. 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. [ABSTRACT FROM AUTHOR]

A calculation method is presented for determining the capacity of small-scale cooling towers equipped with polymeric fills under film flow conditions, for establishing the geometric dimensions and relative position of polymeric fibers comprising the mesh frame, as well as ascertaining the specific flow rate and the cooling tower capacity at which film flow conditions are provided. The presented dependences indicate that a smaller cell size in the fill pack improves the mass flow rate of the liquid to be cooled, which, however, increases the mass of the fill per unit volume of the cooling tower. In addition, it is noted that the reduced size of individual fill cells leads to a rise in the aerodynamic drag coefficient that is proportional to the specific flow rate. [ABSTRACT FROM AUTHOR]

When water supply restrictions increasingly escalate to water supply risks, developing strategies to minimize the water footprint of wet cooling systems becomes crucial. This study compares two water engineering approaches to minimize the water footprint of a recirculating evaporative cooling tower (CT): (1) reusing cooling tower blowdown and (2) producing demineralized water to increase the cycles of concentration (CoC) of the CT. Our techno-economic analysis across various scenarios and CT settings reveals that reusing blowdown (option 1) is the most feasible approach for an industrial cooling system currently operating at CoCs of > 3, discharging blowdown with a conductivity of 2 mS/cm and a total organic carbon (TOC) concentration of approximately 20 mg/L. Compared to enhanced make up treatment, blowdown reuse allows higher water savings (13 %) and involves lower implementation and operation costs. Pilot scale trials validated the feasibility of both approaches. Blowdown and enhanced make up treatment included biologically activated carbon filtration, ultrafiltration and reverse osmosis, producing high-quality permeate, suitable for (re)use as CT make up or within other processes. The blowdown treatment reached a product quality of 80 μS/cm conductivity and 70 μg/L TOC, make up treatment 20 μS/cm in conductivity and 60 μg/L TOC, respectively. The study's findings underscore the viability of blowdown reuse as a cost-effective and efficient strategy to minimize the water footprint of cooling systems under increasing water scarcity conditions. [Display omitted] • Cooling tower feed water quality determines optimal water minimization strategy. • High-quality cooling tower feed water favors cooling tower blowdown treatment. • Cooling tower blowdown treatment and reuse proves feasible in pilot tests. • Reuse of cooling tower blowdown reduces water footprint by 13 %. [ABSTRACT FROM AUTHOR]

Cooling towers are typical high-rise thin-walled structures which are of hyperbolic rotating shell structure type and significantly sensitive to wind loads. Wind-related local instability is the key control factor in the design of structural geometric shape and tower shell thickness optimization. In fact, this kind of stability analysis has only conducted aiming at normal climate (such as monsoon, etc.) under the guideline of series of national Codes. In order to deal with the issues under disaster climate, physical and numerical investigation to evaluate local stability performance of a super large cooling tower (SLCT) under tornado environments based on Buckling Stress State (BSS) method is implemented. Besides, whole process elastic–plastic collapse simulation of the SLCT exposed to the tornados was also carried out to study the failure mechanism and re-evaluated the reasonability of the well-accepted BSS method for structural wind-resistant design. The results revealed that the tornados would have obvious adverse effects on the structural local stability when the SLCT is located at the tornado vortex core radius compared with those under traditional synoptic winds. The swirl ratios and the central distances between the SLCT and the tornado vortex core have significant effects on the local instability of the SLCT. The extended elastic–plastic collapse simulation discovered that the position of the first crack during SLCT collapse process is basically consistent with the critical position from the elastic local stability analysis of the SLCT, indicating that strengthening measures can be carried out in advance at the critical position for structural local stability improvement under tornado conditions. Besides, the extended elastic–plastic collapse numerical simulation of the SLCT could be as the effective supplement to the structural elastic stability assessment (such as BSS method) in the wind-resistant design of the SLCT. • Local stability and failure mechanism of SLCT exposed to tornados were investigated. • Tornado would be more adverse to local stability of SLCT compared to normal climate. • Swirl ratios and central distances have obvious impacts on local stability of SLCT. • Elastic–plastic collapse simulation of SLCT could be as supplements to BSS method. [ABSTRACT FROM AUTHOR]

Very few studies have considered modelling the statuses of loading and component combinations (LC) in chiller systems. This study uses a decision tree (DT) and a neural network (NN) to model accurately six output levels of LC in terms of 11 predictor variables. The NN model gave a higher correct prediction of 89.52% than 84.44% in the DT model. A variable dropout analysis from the DT and NN models generalizes the top five significant variables: the statuses of cooling towers and primary chilled water pumps, and the supply temperature, return temperature and flow rate of chilled water. The system coefficient of performance (SCOP) modelled by NN has an improved R2 of 84.18% versus 74.62% when the significant variables are included as inputs. The SCOP maximization brings three optimal strategies—implementing chiller sequencing, operating components in pairs and optimizing chilled water supply temperature—which reduce CO2 emissions by 99,815–346,987 kg. [ABSTRACT FROM AUTHOR]

With the increasing intensity of the ecological and environmental problems and the scarcity of fresh water, this paper was introduced to investigate the ability to use treated wastewater as a cooling media via studying its behavior throughout a cooling tower. The simultaneous transfer of heat and mass from the treated wastewater to air over splash-fill packing arranged in a zigzag manner was studied. The characteristic of the cooling tower, the outlet water temperature, and the rejected heat were investigated as the water-to-air ratio and inlet water temperature were varied. The core results show that the cooling tower of the tower decreases with increasing water-to-air ratio, and increases with the raise of inlet water temperature. Moreover, relationships between cooling tower and water-toair ratio were obtained for each. It was also observed that the outlet water temperature increases gradually with increasing water-to-air ratio and temperature, and the difference between the inlet and outlet temperature becomes larger by increasing the inlet temperature. The heat rejected value increases with increasing the air-flow rate, water flow rate, and temperature. This study revealed that cooling tower of splash fills arranged in a zigzag manner was higher compared to other types of packing. In the same time, the results for the treated wastewater and fresh water were very close that gives approximate behavior, and this can save a huge amount of fresh water for other humanistic utilization, along with taking benefit from the treatment process of wastewater instead of through it into the aquatic systems. [ABSTRACT FROM AUTHOR]

Global natural resources are affected by several causes such as climate change effects or unsustainable management strategies. Indeed, the use of water has been intensified in urban buildings because of the proliferation of HVAC (Heating, Ventilating and Air Conditioning) systems, for instance cooling towers, where an abundant amount of water is lost during the evaporation process. The measurement of the evaporation is challenging, so a virtual sensor could be used to tackle it, allowing to monitor and manage the water consumption in different scenarios and helping to plan efficient operation strategies which reduce the use of fresh water. In this paper, a deep generative approach is proposed for developing a virtual sensor for probabilistic estimation of the evaporation in cooling towers, given the surrounding conditions. It is based on a conditioned generative adversarial network (cGAN), whose generator includes a recurrent layer (GRU) that models the temporal information by learning from previous states and a densely connected layer that models the fluctuations of the conditions. The proposed deep generative approach is not only able to yield the estimated evaporation value but it also produces a whole probability distribution, considering any operating scenario, so it is possible to know the confidence interval in which the estimation is likely found. This deep generative approach is assessed and compared with other probabilistic state-of-the-art methods according to several metrics (CRPS, MAPE and RMSE) and using real data from a cooling tower located at a hospital building. The results obtained show that, to the best of our knowledge, our proposal is a noteworthy method to develop a virtual sensor, taking as input the current and last samples, since it provides an accurate estimation of the evaporation with wide enough confidence intervals, contemplating potential fluctuations of the conditions. [ABSTRACT FROM AUTHOR]

In this study, real-time predictive control and optimization model based on an ANN (artificial neural network) was developed to evaluate the cooling energy saving performance of the optimized control of CndWT (condenser water temperature). For this purpose, the difference in TCEC (total cooling energy consumption) between the conventional control strategy when the CndWT produced by the cooling tower is fixed and the optimized control strategy when real-time control of the CndWT through the optimal ANN model is applied was compared and analyzed. For the modeling of the building to be simulated, the co-simulation of EnergyPlus and MATLAB was built through the middleware Building Controls Virtual Test Bed. For the prediction of TCEC, an ANN model was developed through MATLAB's neural network toolbox. The model accuracy of the ANN was examined through Cv(RMSE) index and as a result, Cv(RMSE) of the optimized ANN model turned out to be approximately 25 %. More importantly, the predictive control technique was able to save TCEC by 5.6 % compared to the conventional control method constantly fixing CndWT set-point to 30 °C. These results showed that the CndWT needs to be dynamically controlled using artificial intelligence technique such as ANN model and that significant energy savings were achievable compared to the conventional fixed control. [ABSTRACT FROM AUTHOR]

Summary: This study presents a novel design that combines cooling tower (CT) and traditional solar chimney power plant (SCPP) technologies for electricity generation and seawater desalination. The proposed hybrid solar chimney power plant (HSCPP) shares the operation of the chimney part and the bi‐directional turbine between the SCPP and CT, allowing alternative operation of the CT during the nighttime and the SCPP during the daytime, and achieving continuous system utilization. The performance of the HSCPP design was validated against baseline models using 1 year of weather data from the city of Aqaba in Jordan. Results revealed that the HSCPP has the potential to produce ~50% electricity (528 MWh/year) higher than the traditional SCPP (365 MWh/year). The annual seawater desalination capacity of the HSCPP was estimated at 138300 m3, which is 1.5 folds higher than the traditional SCPP. The HSCPP reduced the annual CO2 emissions by 40% (~500 tons) compared to traditional SCPP with annual revenue of US$190 000. Furthermore, the results show that the HSCPP is 1.4 times more efficient than the traditional SCPP. The HSCPP achieved a system utilization factor of 0.73% compared to 0.52% for the traditional SCPP. The HSCPP showed promising sustainable and economical technology for the production of electricity and water while reducing the emission of GHG. [ABSTRACT FROM AUTHOR]

Thermal power plants are users of high water consumption, and the water consumption of cooling towers accounts for more than half of the total water consumption of the whole plant. Therefore, water saving of cooling towers is the key to water saving in thermal power plants. Wave-plate demister as a component of cooling tower influences the performance of entire system. Demister realizes the collection of liquid droplets with the penalty of extra pressure loss. Curved bends and drainage hooks are proposed as enhancing structures of demister to increase separation efficiency and reducing pressure loss simultaneously. Computational result shows that interaction between curved bend and hooks improves the overall performance of demister. Moreover, effect of enhancing parameters on the performance is presented, specifically, Euler number and separation efficiency are correlated as functions of curved bend radius and hook length. Most importantly, an experiment is conducted on a real cooling tower. It shows that the overall thermal capacity is lowered with the presence of demister. Pressure drop, separation efficiency and heat transfer of the entire system are tested with and without demisters, based on which a new criterion is proposed to evaluate the influence of demister on the overall performance of cooling tower in terms of thermal efficiency and droplets collection. Performance indexes as functions of enhancing parameters and droplets dynamic are plotted. Therefore, a quick design of demister can be realized in achieving an optimal performance of cooling tower. [ABSTRACT FROM AUTHOR]

The prospects of using packing materials based on metalworking machine waste as heat and mass transfer blocks for evaporative cooling of industrial recycled water are considered. A procedure is provided for treating experimental data making it possible during analysis of parameters for various packing materials to evaluate the efficiency of their application in specific mass transfer processes and equipment. A procedure is used for processing experimental data making it possible during analysis of a wide range of different packing materials to evaluate the prospects for their industrial application in specific mass transfer processes and equipment. Results of mathematical modeling and design of evaporative cooling equipment for industrial recycled water with the proposed energy and resource-saving heat and mass transfer packing based on metalworking waste are presented. [ABSTRACT FROM AUTHOR]

Cooling towers are structures mainly used in industrial zones such as natural gas facilities, nuclear energy plants, power plants and petrol refineries for supplying cooling water and designed accordingly. The need for industrial facilities in our country has been increasing every passing day. Cooling towers are quite tall and have a big diameter which is why they are exposed to wind loads due to their wide surface area. Considering different seasonal conditions and the hot water circulation, it can be said that thermal effects also have an impact for the cooling towers. In this study that is within this context, as model parameters; 120 m, 160 m, 200 m of heights for concrete shell, 18 m steel columns, 37.5 m s-1 wind speed and temperatures of +20 °C, +40 °C, -40 °C, 30-60 °C are chosen for analyses. Analysis results are evaluated for the chosen parameters. As a result, it was observed that the temperature loads combined with the wind load had a significant effect on the tower shell. [ABSTRACT FROM AUTHOR]

In large-building water systems, Legionella pneumophila is exposed to common environmental stressors such as copper. The aim of this study was to evaluate the susceptibility to copper of L. pneumophila isolates recovered from various sites: two clinical and seven environmental isolates from hot water system biofilm and water and from cooling tower water. After a 1-week acclimation in simulated drinking water, strains were exposed to various copper concentrations (0.8 to 5mg/liter) for over 672 h. Complete loss of culturability was observed for three isolates following copper exposure to 5mg/liter for 672 h. Two sequence type 1427 (ST1427)-like isolates were highly sensitive to copper, while the other two, isolated from biofilm samples, maintained higher culturability. The expression of the copper resistance gene copA evaluated by reverse transcription-quantitative PCR (RT-qPCR) was significantly higher for the biofilm isolates. All four ST1427-like isolates were recovered from the same water system during an outbreak. Whole-genome sequencing results confirmed that the four isolates are very close phylogenetically, differing by only 29 single nucleotide polymorphisms, suggesting in situ adaptation to microenvironmental conditions, possibly due to epigenetic regulation. These results indicate that the immediate environment within a building water distribution system influences the tolerance of L. pneumophila to copper. Increased contact of L. pneumophila biofilm strains with copper piping or copper alloys in the heat exchanger might lead to local adaptation. The phenotypic differences observed between water and biofilm isolates from the hot water system of a health care facility warrants further investigation to assess the relevance of evaluating disinfection performances based on water sampling alone. IMPORTANCE Legionella pneumophila is a pathogen indigenous to natural and large building water systems in the bulk and the biofilm phases. The immediate environment within a system can impact the tolerance of L. pneumophila to environmental stressors, including copper. In health care facilities, copper levels in water can vary, depending on water quality, plumbing materials, and age. This study evaluated the impact of the isolation site (water versus biofilm, hot water system versus cooling tower) within building water systems. Closely related strains isolated from a health care facility hot water system exhibited variable tolerance to copper stress, shown by differential expression of copA, with biofilm isolates displaying highest expression and tolerance. Relying on the detection of L. pneumophila in water samples following exposure to environmental stressors such as copper may underestimate the prevalence of L. pneumophila, leading to inappropriate risk management strategies and increasing the risk of exposure for vulnerable patients. [ABSTRACT FROM AUTHOR]

Biofilm is a microbial population which live in a self-produced extracellular polymeric matrix by attaching to surfaces. Biofilms consist of different different types of organisms such as bacteria, fungi, protozoa, etc. Many biofilms that develop in nature consist of more than one type of organism. Biofilms protect bacteria from adverse conditions such as temperature fluctuation and disinfectants. The aim of this study was to determine the effective elimination strategies for combating biofilm and planktonic bacteria in cooling tower model system using different decontamination / disinfection techniques. In this study, 14 week-old biofilms were treated with temperatures of 4 °C, 65 °C; pH of 3, 11; 2 and 10 mg/l chlorine, 2 and 10 mg/l monochloramine; hypotonic salt (0.01% NaCl) and hypertonic salt (3% NaCl) solution. For enumeration, number of aerobic heterotrophic bacteria was determined by conventional culture method, number of live bacteria was determined by LIVE/DEAD viability kit, CTC-DAPI and Alamar blue staining methods. Temperature of 65 °C, pH of 3, 10 mg/l monochloramine and hypertonic salt solution were the most effective parameters for decontamination of biofilm and planktonic bacteria. Biofilm bacteria in the circulating water system were significantly more resistant than planktonic bacteria against stress factors. When the numbers of epifluorescence microscopy and conventional culture technique were compared, significantly higher number of live bacteria were detected using epifluorescence microscopy. Bacteria enter the viable but non-culturable phase by loosing their culturability under stress conditions. For this reason, the conventional culture method should be supported by different techniques to get more realistic numbers. [ABSTRACT FROM AUTHOR]

Sensible and latent heat rejection from heat engines is of high necessity for system efficiency and continuous production. The cooling tower is one of the major heat-exchanging systems used for cooling industrial heat systems by intimately mixing hot water with cooling air. Optimal operating conditions and parameters of the system are highly essential for its effectiveness and efficiency. This study used the Poppe model to evaluate selected thermodynamic relations of a rectangular counter-flow industrial cooling tower of a steel rolling mill using the system's inlet and outlet data as initial conditions. The effect of increasing the water temperature on the air moisture content, Merkel number, and specific enthalpy was studied across the fills of the cooling tower. Air moisture content, Merkel number and specific enthalpy of the system increase with increasing water temperature. However, while other variables reach a stationary point at half the nodal segments, the specific enthalpy increases across the fills in the system. It was concluded that the use of nano particles with high heat removal rate could increase the efficiency of the system. Also, an increase in the quantity of the makeup water of a force draft system is recommended towards increasing the system efficiency. [ABSTRACT FROM AUTHOR]

The results of experimental studies of hydraulic resistance, heat and mass transfer characteristics of a prismatic lattice polymer regular packing for various options of its installation in space are presented. Based on the conducted experimental studies, the most rational design of packing installation was determined (taking into account the decrease in hydraulic resistance and the increase in the efficiency of heat and mass transfer processes), for which the geometric characteristics are given and empirical dependences are obtained, which make it possible to determine the value of the hydraulic resistance of the dry and irrigated packing, the values of the volumetric coefficients of mass transfer and heat transfer. The results of the study can be used in enterprises where different types of cooling towers or devices for conducting heat and (or) mass transfer processes, such as absorption, are used, as well as in the development of packed scrubbers. [ABSTRACT FROM AUTHOR]

In the present work, a Matlab® computer code for cooling tower simulation was developed to perform a parametric analysis that determines the effect of the column cross-sectional area on multiple operating variables such as air humidity, air and water outlet temperature, among others. The computer code uses the Merkel's model and the CDAWC (Continuous Differential Air-Water Contactor) model for later comparison. It was observed a decrease in the outlet water temperature by approximately 14% when the tower's cross-sectional area increased from 1 to 2 m2. It increases the air outlet temperature by about 17% due to increased air-water contact. A negative convective heat transfer in the air was obtained in the cooling tower´s bottom due to the large amount of energy required for the heat transfer by vaporization, which was much larger than the convective heat. The evaporative heat transfer is over 80% of the total heat transferred. [ABSTRACT FROM AUTHOR]

The cooling water system is an indispensable part in the removal of the indoor cooling load in heating, ventilation, and air‐conditioning (HVAC) systems. However, the complexity and strong coupling characteristics of the controlled objects lead to unsatisfied control effects in most practical engineering applications. In this paper, the cooling water system is studied as a whole from the perspective of online application. Firstly, the mathematical models of the cooling water system are introduced and simplified based on the experimental data from the actual system. The simplified models have easy obtained inputs and programmable structure, which renders higher feasibility and practicality for the model‐based control method applied in the real system. On this base, an easily implemented control method for cooling water system is proposed to improve the global efficiency. By comparing with the conventional constant temperature difference control strategy and constant speed control strategy in the simulation platform, the proposed water flow optimization control strategy is superior in both global COP and energy saving at the same operating conditions, and 0.37% and 3.45% of energy consumption can be saved, respectively. The simulation results imply that the proposed simplified method is a referable control method for designing or retrofitting the real cooling water system. [ABSTRACT FROM AUTHOR]