Cooling Water System Research Articles

Physicochemical Characteristics and the Scale Inhibition Effect of Air Nanobubbles (A-NBs) in a Circulating Cooling Water System

Air nanobubbles (A-NBs) in a circulating cooling water system have not been investigated, although their role is significant. In this paper, the influences of the contents of main salts and other parameters on the physicochemical characteristics and scale inhibition performance of A-NBs in circulating cooling water were investigated and the scale inhibition mechanism of A-NBs in a simulated circulating cooling water system was explored. A-NBs realized a higher scale inhibition rate of 90%, which was higher than that of 1-hydroxyethane-1,1-diphosphonic acid (40%), and A-NBs stably existed for more than 5 days in the complex water environment. Four interface functions were proposed to interpret the scale inhibition effect of A-NBs in circulating cooling water as follows. First, the negatively charged surface of A-NBs adsorbed cations (Ca2+) reduced the concentration of scaling ions. Second, the negatively charged surface of A-NBs could also adsorb microcrystals, and their crystal-like seed action was conducive to the formation of large-size crystals, broke the rules of crystal growth, and reduced the adhesion of scales to the pipe wall. Third, A-NBs could also form a bubble layer after they were adsorbed on the inner surface of pipes, thereby preventing the deposition of scales on the surface. Fourth, A-NB burst caused local turbulence, increased the shear force onto the pipe surface, and reduced the scales adhering to the pipe surface. The interface effect of A-NBs in metal pipes is important in many industrial applications. This study laid the basis for the development of a new green A-NB scale-inhibiting technology.

Research on scale inhibition law of high sulfate mine water based on response surface methodology

AbstractThe problem of scale inhibition in thermal power plants using mine water as circulating cooling water is a major focus of current engineering attention. Mine water in North China is predominantly high sulfate mine water, with mine water in Shanxi mines generally having a sulfate content of over 1000 mg/L. Currently, most thermal power plants blindly follow the previous scale inhibitor with carbonate scale as the main scale inhibition target, which leads to a large amount of sulfate scale in its circulating cooling system, which is difficult to remove after the formation of sulfate scale. On the basis of the experiments, the corresponding scale inhibition laws were studied using the response surface method for the water quality characteristics of high sulfate mine water. The scaling process on the heat exchange surface of the circulating cooling water system was simulated by the hanging sheet deposition method, and the quantitative analysis was carried out by the weight method. Using EDTMPS as an example, the scale inhibition law of sulfate‐type scale inhibitors for this type of mine water was systematically investigated. The experiments showed that the scale inhibition rate (reduction of deposited scale after scale inhibitor dosing) reached a peak of 95.21% at a time of 6.1 h, a solution temperature of 70°C and an EDTMPS dosing rate of 6 mg/L.

Roles of Microbial Extracellular Polymeric Substances in Corrosion and Scale Inhibition of Circulating Cooling Water

Circulating cooling water plays a major role in petrochemical electric power, steel, metallurgical, and other industries. Corrosion and scale inhibitors in circulating cooling water systems face the challenges of high cost, low efficiency, and heavy pollution. Extracellular polymeric substances (EPS) were considered as novel, efficient, and environmentally friendly corrosion and scale inhibitors in circulating cooling water systems due to their availability, high efficiency, and lack of benefit from secondary pollution. However, roles of EPS in corrosion and scale inhibition remain unknown yet. Herein, Gram-negative (Pseudomonas putida) and Gram-positive (Bacillus megaterium) bacteria were selected to explore the corrosion and scale performance and mechanisms of soluble EPS (s-EPS). Performances of s-EPS from P. putida (s-EPS-P. putida) in corrosion and scale inhibition were obviously superior to those of s-EPS from B. megaterium (s-EPS-B. megaterium). The previously undiscovered roles of s-EPS in corrosion and scale were uncovered: (1) the chelating ability of s-EPS (mainly humic substances) prevented the formation and growth of CaCO3 crystals; (2) s-EPS (mainly carbohydrates) formed a dense protective film by integrating with metal ions on a carbon steel surface to prevent the corrosion of A3 carbon steel. Our work provides a deeper mechanistic understanding of corrosion and scale inhibitory performances, allowing advanced development and optimization of s-EPS as a corrosion and scale inhibitor.

Biofouling characteristics in Xinghua Bay of Fujian, China

Biofouling is one of the main factors affecting the efficiency and safety of cooling water systems in coastal nuclear power plants. Understanding the population dynamics, succession rules and cumulative effects of major fouling organisms is the basis for targeted prevention and control. A 1-year simulated concrete panel test was conducted from December 2020 to November 2021 in Xinghua Bay, China. A total of 78 species of fouling organisms were recorded by combining the monthly, seasonal, semiannual, annual and monthly cumulative panels, and the community composition was dominated by nearshore warm-water species, making for a typical subtropical inner bay-type community. The fouling organisms had a peak attachment period from June to October. Significantly more attachment was observed during summer (from June to August) than during the other three seasons. The attachment amount in the second half-year (from June to November) was much higher than that in the first half-year (from December to May). The attachment thickness, density, and biomass of the bottom summer panels reached 20 cm, 105,150 ind./m2, and 19,274.50 g/m2, respectively, while those of the bottom annual panels were 40 cm, 27,300 ind./m2, and 17,762.50 g/m2, respectively. The dominant fouling organisms with calcified shells mainly included Amphibalanus reticulatus and Pernaviridis. These species had high attachment amounts,could accumulate attachments for a long time, and even might cause secondary blockage, making them the most detrimental to the safety of a cooling system. Moreover,the seasonal upward growth of hydroids and bryozoans can also significantly reduce the efficiency of cooling water intake. We suggest that targeted prevention and control should be carried out according to the larval attachment period of different dominant groups of fouling organisms during June-October, which can greatly improve the prevention and control efficiency. Strengthening the research on the biological cycle phenomenon of the main species and their main environmental impact factors, and establishing a scientific and effective early-warning model are the governance direction of formulating and implementing scientific pollution prevention and control in the future.

Aggregation process of two disaster-causing jellyfish species, Nemopilema nomurai and Aurelia coerulea, at the intake area of a nuclear power cooling-water system in Eastern Liaodong Bay, China

The intake safety of nuclear power cooling-water systems (NPCSs) is an important aspect of operational safety of nuclear power plants (NPPs). The blockages caused by aberrant outbreaks of various aquatic organisms have seriously affected operational safety. Large jellyfish constitute the main groups of marine organisms responsible for these blockages. The processes of aggregation and the relationships of two major disaster-causing scyphozoan jellyfish species, Nemopilema nomurai and Aurelia coerulea, with four environmental factors at the intake area of an NPCS in Eastern Liaodong Bay, China, were investigated in 2019 and 2020. The findings revealed that A. coerulea ephyrae were present in the surrounding ports in mid-May; however, N. nomurai ephyrae were absent during the survey period in this study, and the medusae of N. nomurai started appearing from late May. The individual growth and relative biomass (RB) of the jellyfish increased rapidly from late June to July and decreased rapidly thereafter, in September. The RB of N. nomurai was highly correlated to the sea surface temperature (SST) and levels of dissolved oxygen (DO) in the region. The RB increased with increasing SST and decreased at increasing DO levels. The RB of A. coerulea was significantly negatively correlated with that of N. nomurai, and the peak biomass of the two species alternated over time, which could be attributed to the fact that the jellyfish species share similar ecological niches. The bell diameters were significantly positively correlated with the individual wet weights, and the value of one could be inferred from the value of the other. Although the processes of jellyfish aggregation are attributed to several factors, including interactions with environmental factors and human activities, such as fishing, the results obtained in this study would serve as an important reference and provide a basis for the prevention of jellyfish blooms in waters adjacent to NPPs. The prevention and control of jellyfish disasters at the intake area of NPCSs are not only local concerns. Therefore, remediation from the source combined with the maximum utilization of social resources for monitoring and early warning would immensely improve the efficacy of such preventive strategies.

Energy-efficient Pump Control in Industrial Cooling Water Systems Using a Multi-Agent System

Nations worldwide are facing the challenge of reducing their greenhouse gas emissions. Thermal energy supply systems in industrial companies account for 75 % of their final energy demand, and are therefore of particular importance. Regarding thermal energy distribution, 3 % of the industrial final energy demand is used for pumps. Especially in cooling water systems, the largest share of energy demand accounts for pumping systems. Currently, industry usually uses operating strategies that provide pressure control without considering individual pump operating points and efficiencies. However, research shows that more intelligent operating strategies can improve the energy efficiency of such systems significantly. Therefore, this paper presents a collaborative multi-agent approach to control the pumping system in a central cooling water system considering the energy efficiency of each pump agent. This approach is compared with a conventional operating strategy using a centralized, rule-based decision making process to control the system's feed pressure.In a first step, each agent calculates the energy efficiency difference to its optimum and whether it wants to increase or decrease its rotational speed to reach its optimum. This information is collected by a organization unit and distributed to all agents. Then, depending on the system requirements and the states of the other agents, each agent decides whether to adjust its own rotational speed or leave it to another agent showing a higher difference to its optimum. The multi-agent system is implemented within a Python framework and validated for a central cooling water system using a dynamic simulation model. For an exemplary use case, the energy efficiency of the overall system improves up to 12.4 % against the baseline while still ensuring operational requirements.

Numerical modelling of the cooling water system of a 106MW Hydro-Power Plant using EPANET

The present paper studies the behavior of the new proposed cooling water pumps for a 106 MW Hydro-Power Plant using EPANET. This case-study Hydropower Plant, located in the south of Romania and equipped with two Francis units 53 MW each, processing a 269m gross head, presently goes through a rehabilitation process. The cooling water system of this Hydro-Power Plant consists in four centrifugal pumps, two for each unit, and two additional pumps for the 130 MVA step-up transformer. The rehabilitation process involves the replacement of these pumps. A numerical model following the exact configuration of the cooling water system in what regards pipes diameters, lengths and roughness was designed in EPANET. The focus is to verify if the required pressure is ensured at the cooling water consumers of the plant considering their specific flow demand and if the velocity in the system pipes is within the acceptable limits during the power production process.

All-Ceramic Heat-Flux Sensor for Continuous Measurement Under High Temperature and Harsh Environmental Conditions

In this study, an all-ceramic heat-flux sensor with high temperature resistance and no water-cooling system was designed to address the problems of short effective lifespan and low sensitivity of heat-flux sensors under harsh ultra-high temperatures and high heat-flux conditions. The sensor components comprised high temperature resistant ceramic materials, that is, alumina (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ), indium tin oxide (ITO)-In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thermopile, and nano SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Structural parameters of the proposed heat-flux sensor were optimized via simulations. A high-temperature test platform was built to evaluate the sensor performance; the sensor exhibited an excellent thermoelectric performance. The output voltage of the sensor reached 9.96 mV at 1300 °C, and the average sensitivity in the range of (50–340) kW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> was 31.5 μV/(kW∙m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ). The drift rate of the proposed sensor in the high-temperature maintenance experiment at 1200 °C for 5 h was 2.7 (kW/m²)∙h <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The time constant of the sensor under pneumatic heating was 2.3 s. The proposed sensor can continuously work at ultra-high temperatures; therefore, it can be practically employed in the heat flux measurement of turbines and supersonic aircrafts.

Method for Increasing Net Power of Power Plant Based on Operation Optimization of Circulating Cooling Water System

Method for Increasing Net Power of Power Plant Based on Operation Optimization of Circulating Cooling Water System

A Key To Sustainable Development-Solar Powered Water Cooling System

A Key To Sustainable Development-Solar Powered Water Cooling System

Enhancing solar panel efficiency through cooling techniques: A review

This study focuses on investigating the impact of temperature on solar panels and explores various cooling techniques to enhance their efficiency. The electric power output and efficiency of Photovoltaic (PV) cells decrease as the temperature increases. The temperature reduction depends on the type of solar panels and their temperature coefficient, which typically falls within the range of -0.3% to -0.5% per degree °C. The objective of this study was to determine the most effective cooling technique for solar systems. This study analyzed and compared various cooling methods and revealed that when water cooling is applied on both sides of a solar panel, it is the most efficient method to increase the efficiency by approximately 14.1%. Furthermore, the water-cooling system achieved a temperature reduction of up to 20 °C. The advantage of water cooling supports the self-cleaning of the solar panels, which further enhances their efficiency. The ability of water to remove dust and debris from the panel surface helps maintain optimal performance over time. The findings of this study provide valuable insights into the selection of the most suitable cooling technique for solar systems. Water cooling in solar panels offers substantial improvements in efficiency and temperature reduction.

Design of a high power solid target for 211At

The new SPIRAL2 LINAC at GANIL delivers light beams (p, d, alpha,…) with very large intensities. In order to exploit these beams in an optimal way, high power target stations are requested. In this contribution, we present such an irradiation station designed to optimize the production of 211At, an alpha emitter of interest for targeted alpha therapy. In order to dissipate at least 10 kW of beam power, a rotating, water-cooled system comprising twelve individual targets has been developed together with a fast and safe extraction mechanism.

Study of the influence of cooling water quality and inhibitors on the corrosion rate of brass in cooling water

At present, our country does not have an effective programme for the organization of water-chemical regimes of circulating refrigeration systems, solving three problems at the same time: the prevention of sedimentation, Reduction of corrosion rates of copper-based construction materials and avoidance of biological growth within the system and on heating surfaces. In addition, the influence of cooling water quality on the corrosion of copper-containing alloys in high-inertial water-cooling systems of turbine condensers has also been largely unknown. The use of film-forming amines (in particular, chelamine and octadesilamine) is a promising method to address this problem, but information on this issue is scarce. Therefore, it is essential to optimize the water-chemical modes of recycling cooling systems of turbine condensers in order to reduce the corrosion rate of brass. Thus, the aim of the work is to study the influence of the quality of cooling water and corrective reagents on the corrosion rate of brass in order to optimize the water-chemical modes of cooling systems of turbine condensers.

Improving energy efficiency of photovoltaic/thermal systems by cooling with PCM nano-emulsions: An indoor experimental study

This study was to evaluate the application of phase change material nano-emulsions as novel coolants for improving the overall efficiency of liquid-cooled photovoltaic/thermal systems. A self-designed lab-scale photovoltaic/thermal module was constructed with serpentine cooling tube of two different geometries. Two phase change material nano-emulsions with a melting point 29 °C or 38 °C were evaluated at various flow rates and solar irradiance periods on the energy and exergy efficiencies. The total thermal-equivalent energy efficiency was 84.41% on average and 89.23% maximum for the module by employing the nano-emulsion, in comparison to 79.95% and 83.23% in the water-cooled system, while the total exergy efficiency was 10.69% with the nano-emulsion, even lower than that of 11.66% with water. The results also suggested that latent heat release in a narrow temperature range was essential for a better energy performance using the nano-emulsion as a coolant. A relatively low flow rate of the nano-emulsion was usually favorable to the overall energy efficiency in consideration of pump power. Moreover, particle size and thermal properties of the nano-emulsion before and after the operation in the systems showed only marginal differences, indicating the high stability for long-term usage in liquid-cooled photovoltaic/thermal systems with performance enhancement.

Assessment of Biogrowth at Two Different Environments of Nuclear Power Plant Cooling Water System Located at Southern Coast of India

A systematic assessment of biogrowth development on titanium coupons exposed to ambient seawater (intake) and chlorinated seawater (pump house) environments of a coastal nuclear power plant was carried out. Titanium coupons were exposed for a period of 2 years and periodically removed at monthly intervals for biogrowth assessment. Biofouling biomass at the seawater intake station ranged from 0.8-12.5 kg m-2 during the 2 years of study. Continuous chlorination of 0.2 ± 0.1 mg L-1 and shock dose chlorination for 1 h/day at residuals of 0.4 ± 0.1 mg L-1 was very effective in reducing the biofouling load in the cooling water system. A reduction in fouling biomass of 95% was observed on titanium coupons between the intake and the pump house stations. Biofoulants recruitment was found to occur throughout the year at varying intensities. Diversity of organisms on the coupon was influenced by seasonality and distinct successional patterns were observed at the seawater intake. Barnacles were the dominant fouling organisms followed by mat forming ascidians, bryozoans, oysters, hydroids and seaweeds at the intake station. Sluggish biofouling development was observed on coupons at the intake due to the sub-tidal intake system (-5 m), which had a lesser load of meroplanktonic organisms. The study also showed that low dose continuous chlorination was an effective strategy for biofouling control in the cooling water system of the tropical power station which uses titanium heat exchangers for steam condensation.

Machine learning-based thermo-electrical performance improvement of nanofluid-cooled photovoltaic–thermal system

Hybrid photovoltaic–thermal (hPVT) collectors are devices that allow the conversion of sun energy into useful thermal and electrical energy simultaneously. The power obtained from the photovoltaic (PV) module introduces random fluctuations into the system. While obtaining the data for PV power output in advance and for reducing the impact of random fluctuations, exact day-ahead PV power prediction is crucial. Machine learning algorithms have been proven an effective tool in PV technology for day-ahead prediction of PV-power output. This research employs the Gaussian process regression method using the Matlab environment for forecasting the hPVT collector's performance operating with pure water and Fe/water nanofluid. A one-year historical data pertaining to solar irradiance as well as ambient temperature for Roorkee (29.8543 °N, 77.8880 °E), India location has been used to validate the proposed model. This data is utilized for day-ahead forecasting of solar irradiance and ambient temperature. The outcome elucidates that as the mass-flow rate increases, the thermo-electric performance of the hPVT collector enhances. Raising the mass-flow rate of Fe/water nanofluid from 0.01 to 0.1 kg/s, the cell temperature decreases by 9.35 °C and 9.47 °C, respectively, for the actual and predicted data. The thermal, electrical, as well as overall efficiency of the hPVT collector, improves by 2.73%, 7.11%, and 9.84%, respectively, using Fe/water nanofluid ( ϕ = 2%) in contrast to the water-cooled PVT system. Finally, results demonstrate that the outcomes obtained using the forecasted data closely follow the results obtained using the actual data. In conclusion, this analysis provides a comprehensive solution for utilizing nanofluids as a coolant in the most cost-effective ways.

A Development of Meso-Scale Vortex Combustion for a Micro Power Generator Based on a Thermoelectric Generator

The development of portable electronic devices has increased; this development needs to be accompanied by the development of reliable power sources. In this study, two different vortex combustor sets were used in conjunction with a thermoelectric generator to determine their energy output. This study focuses on the development of a meso-scale vortex combustor to obtain the electric energy for a micro power generator; different materials and different vortex designs are analyzed. Numerical and experimental methods have been used to analyze the development of the vortex combustor. A horizontal vortex combustor made from stainless steel had higher wall temperature and voltage output measurements. To analyze the energy output for the micro power generator, a single TEG and double TEG are analyzed; according to the results, a double TEG with a water-cooled system has the highest electric power compared with the other results.

Thermal‐Driven Soft‐Contact Triboelectric Nanogenerator for Energy Harvesting and Industrial Cooling Water Monitoring

In this paper, a quaternary dielectric soft-contact rotary triboelectric nanogenerator (QDSR-TENG) of low frictional resistance is fabricated for combining TENG with a shape memory alloy (SMA) engine. The introduction of rabbit fur brush and FEP brush results in charge pumps with a partially soft contact structure. Benefiting from the low friction loss of the structure, the QDSR-TENG can operate stably and continually for 100k cycles without significant output degradation. The SMA engine exhibits thermally induced phase transformation and super-elasticity and can be utilized for harnessing waste heat energy. The thermal-driven QDSR-TENG can operate with a water source of 43°C with a distinguishable response to the variation of temperatures. Such a low starting temperature not only promotes the harvesting of low-grade thermal energy, but also results in a self-monitoring industrial cooling water system. The coupled elastocaloric power and cooling cycle proposed in the thermal-driven QDSR-TENG opens a new paradigm for the application in energy harvesting and smart sensing.

Ultrasonic Vibration Technology to Improve the Thermal Performance of CPU Water-Cooling Systems: Experimental Investigation

The rapid growth of the electronics industry and the increase in processor power levels requires new techniques to improve the heat transfer rate in their cooling systems. In this study, ultrasonic vibration technology was introduced as an active method to enhance the thermal performance of water-cooling systems. The effects of ultrasonic vibrations at power levels of 30, 60, and 120 watts for different cooling airflow rates were investigated experimentally. The results were validated with available empirical correlations to ensure the accuracy of the measurement systems. The findings indicated that the ultrasonic vibrations enhanced the heat transfer in the liquid-cooling heat exchangers. In addition, the thermal performance of the ultrasonic vibrations was improved by reducing the airflow rate and increasing the ultrasonic power. In addition to the feature of heat transfer improvement, ultrasonic waves are widely used for the cleaning of different types of heat exchangers. Regarding the anti-fouling and anti-accumulation effects of the ultrasonic vibrations, the introduced technology could provide a practical way for developing high-performance nanofluids-based computer cooling systems.

Model free optimization of building cooling water systems with refined action space

Model free optimization of building cooling water systems with refined action space