Results 1 - 10 of 15
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[en] The paper considers the operating effect of the evaporative cooling towers of the Belarusian NPP on the formation of the local microclimate. The formation mechanisms and conditions for the occurrence of such natural phenomena of fogging and icing are analyzed. Mathematical modeling of the dynamics of moisture-containing emissions from the cooling tower was carried out taking into account the moisture content of the environment and the processes of icing. In order to determine and predict ice loads on power lines, an example of modeling the icing process is given: the deposition of liquid droplets on the surface of the wire, the calculation of the thickness and shape of the layer of ice formed. (authors)
[en] In this research, a series of experiments have been performed to study the thermal resistance of an oscillating heat pipe equipped with cooling tower. The effects of filling ratio and input heating power on the thermal resistance of the heat pipe and temperatures of different sections of evaporator and condenser of the heat pipe are investigated and discussed. All tests are taken for input heating power and filling ratio in the ranges of 20–200 W and 10–60%, respectively. A correlation for the thermal resistance is presented, which the effects of input heating power and filling ratio are taken into account in this correlation. The results showed that the heat pipe with filling ratio of 40% and input heating power of 160 W has the minimum value of thermal resistance among all cases considered in this research. Moreover, the thermal resistance decreases about 86% as the input heating power increases in the range of 20–120 W, while this reduction is only 23% by increasing the input heating power in the range of 160–200 W.
[en] This study aimed to investigate the antibiofouling activity of 3-(trimethoxysilyl)-propyl, alkyldimethylammonium chloride-based (SilQUAT)-treated glass fiber-reinforced polyester (GFRP) composite panels in model cooling tower system. All surface characterization analyses were performed by using FTIR and XPS and showed that surface chemical composition peaks confirmed the successful coating of compound. The antibiofilm efficacy of the SilQUAT-treated GFRP panels was evaluated with culture, ATP measurement and live/dead fluorescence staining, for 6 months. To mimic mechanical interventions, the durability and residual self-sanitizing activity of the treated GFRP panels was tested by modifying the EPA # 01-1A protocol, after abrasion. At the end of the 6-month period, the antibacterial effect was 95% and 99.90% for abraded and non-abraded materials, respectively. The current study provides an alternative application to prevent biofilm at source by modification and imparting antibacterial properties to the material. Prevention of biofilm at its source is an important approach by providing indirect benefits such as the reduction in corrosion and secondary environmental pollution caused by the use of excess biocides, and consequently, the reduction in cost and the risk of harm to the public/environment will also be of interest.
[en] The RSG-GAS cooling system consists of primary and secondary cooling systems. The primary cooling system functions to take heat from the reactor core while the secondary cooling system serves to take heat from the primary cooling system through a heat exchanger and release it to the environment. The reactor coolant system has been operating for more than 28 years so it needs revitalization. One part that is replaced is the cooling tower. The reactor coolant system capability after revitalization can be seen through the comparison of secondary and primary cooling system calorimetry power and comparing the Tinlet and Toutlet reactor coolant systems with their design values. From the results of the comparison, the change in calorimetry power on the primary side is proportional to the change in the secondary side calorimetry power. This shows the heat transfer from the primary to the secondary cooling system and the process of releasing heat to the environment goes well. For a comparison of the reactor coolant Tinlet-Outline at full power of 30 MW, the Tinlet-Outflow of primary and secondary cooling systems does not exceed the maximum design limit value. From all comparisons showing a new cooling tower the secondary cooling system provides a better level of heat dissipation when the reactor operates. (author)
[en] Energy balance closure is the main indicator of the quality of energy flux measurements obtained by the eddy covariance technique. Many researchers use a simple linear regression model between energy balance components to evaluate closure. However, these studies typically fail to verify the appropriateness of the statistical assumptions of regression analysis, which can lead to erroneous conclusions if the model is not satisfactory. Thus, the aim of this study was to calibrate and validate simple and robust with bootstrap and cross-validation linear regression models to verify the efficiency of energy balance closure in the Amazon ecosystem. Measurements of net radiation and latent, sensible, and ground heat fluxes were made from January to December 2008 in a tropical rain forest area in South West Amazonia in an experimental site belonging to the network of flux towers of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA). The results demonstrated that simple linear regression models are not appropriate for analyzing energy balance closure. However, robust linear regression models with bootstrap and cross-validation improved the fit to the data. Despite the better fit, there was an increase in energy balance closure residuals suggesting that the eddy covariance technique is underestimating the values of energy fluxes in Amazon forest areas more than what were reported in previous researches.
[en] One important component of the reactor coolant system is the cooling tower. The RSG-GAS cooling tower has been operated for more than 30 years. The study of the performance of cooling towers has been carried out at a nominal power operation of 30 MW in terms of the safety of reactor operations. The study was conducted to determine the performance of cooling towers in removing heat into the environment. Parameters for evaluating the performance of cooling towers used include the range, approach, effectiveness, efficiency and coolant temperature entering the reactor core. From a 1992 operational data study, a range value of 7,2 oC was obtained, the approach value of 8,0 oC, the effectiveness value of 47.37 %, and the temperature of the cooling inlet temperature was 40.0 oC. From a 2018 operational data study, the range value of 6.7 oC was obtained, the approach value of 9.3 oC, the effectiveness value of 41.84 %, and the cooling inlet temperature value was 41.96 oC. The value of the cooling temperature entering the core in 1992 was below the reactor protection system activation limit, while the value of the cooling temperature entering the core in 2018 approached the reactor protection system activation limit. It can be concluded that the performance of cooling towers after 30 years operation cannot meet the safety criteria of reactor operations. (author)
[en] The water distribution system of the cooling tower is to sprinkle the hot water on the top surface of the packing evenly. The uniformity of water dripping has a great influence on the cooling effect of the cooling tower, which is directly related to the efficiency, energy consumption and investment of the cooling tower. The design of water distribution of a super large natural counter flow seawater cooling tower (17500m2) in a nuclear power plant is carried out in this paper. Based on the weather conditions and the layout scheme of the packing, the water distribution scheme is optimized by hydraulic calculation and cooling performance composition. The final scheme meets the requirements of cooling tower water distribution uniformity and winter anti freezing operation, and improves the heat transfer efficiency of the cooling tower. (author)
[en] Climate change and environmental commitments force the need to make improvements in energy systems. Improving efficiency is one way to contribute to the goal of reducing impact on the environment. Gen energija, the owner of the Slovenian part of the nuclear power plant (NPP) in Krško, is constantly trying to improve operation of its generating units. GEN carried out a feasibility study on cogeneration in NPP Krško. The study analysed potentials of heat utilisation, potential customers and heat demand in the area. Another example of efficiency enhancement is managing the hydro power plants on Sava River in synergy with NPP Krško. With coordinated operation of hydropower plants on Sava River and NPP Krško cooling towers, noticeable energy savings were achieved. (author)
[en] ETRR-2 is an open pool research reactor of nominal power 22 MW cooled with light water. The core is composed of 29 fuel elements of MTR type with 19 fuel plates each. The core cooling system (CCS) consists of two coolant loops through which a coolant flow rate of 1950 m3/h is pumped. The coolant goes through the core in upward flow where it removes the heat generated and then through heat exchangers where the heat is transferred to the secondary coolant system, (SCS). Operation with two coolant loops is known as two pumps operation mode. About 50 m3/h of the coolant flow returning from heat exchanges is diverted to the reactor pool to provide a downward flow in the chimney preventing core activated water from reaching the pool top. The secondary coolant system with flow rate of 3055 m3/h is responsible for the final dissipation of the heat generated in the reactor core. It consists of cooling tower, pipes from the tower to the heat exchangers, and secondary pumps. Two plate type heat exchangers are used in the coolant systems. In the heat exchanger, the heat transfer area is composed of series of corrugated plates which means that each two plates form a flow channel. A complete description is given and a schematic view of the ETRR-2 primary and secondary coolant systems is shown.
[en] The layout and the water intakes of a small modular reactor are quite different from previous nuclear power plants (NPPs). There are three main problems with the water intake engineering in this small modular reactor: the water supply problem of the service water system during the plant maintenance; the problem of biofouling in the water intake tunnel; and the high unit energy cost (UEC) of water intake engineering. In order to solve these problems, a variety of solutions are proposed and analyzed in this paper. (author)