Papers by Keyword: Flux

Abstract: Heat removal from nuclear reactor core has been one of the major Engineering considerations in the construction of nuclear power plant. At the center of this consideration is the nuclear fuel pellet whose burning efficiency determines the rate of heat transfer to the coolant. This research, focuses on the study of temperature distribution of solid fuel, temperature distribution of annular fuel with external cooling and the temperature distribution of annular fuel with internal and external cooling. We analyzed the different distribution and made a conclusion on the possibility of improving temperature management of Nuclear fuel rod, by designing fuel pellets based on this geometrical and thermal Analysis. To date, a lot of studies has been done on the thermal and geometrical properties of Nuclear fuel pellet, it is observed that annular fuel pellet with simulteneous internal and external cooling can achieve better temperature distribution which leads to high linear heat generation rate, thus generating more power in the design [1]. It has also been observed that annular fuel pellets has low fission gas release [10]. In large LOCA, the peak cladding temperature of annular fuel is about 600 which is significantly less than that of solid fuel (920 ), this is due to the fact that annular fuel cladding has lower initial temperature and the thinner annular fuel can be cooled more efficiently than the solid fuel. One of drawbacks of annular fuel technology is “the fuel gap conductance assymmetry” which is caused by outward thermal expansion, it has a potential effect on the MDNBR (Minimum Departure from Nucleate Boiling Ratio), which is the minimum ratio of the critical to actual heat flux found in the core [10]. In this model, we used the ceramic fuel pellet of UO₂ as our case study. All the parameters in this model are assumed parameters of UO₂. The Heat Transfer tool (ANSYS APDL) was used to validate the Analytical Model of this research.

Abstract: Presented are the results of the use of metallurgical wastes as constituents of welding fluxes. On the basis of fine particle gas purification in aluminum production, a carbon fluoride additive (FD-UFS) has been designed for welding fluxes which allows for manufacturing of steel constructions of northern execution with improved mechanical properties of welded joints. It is shown that the introduction of FD-UFS to fluxes AN-348, AN-60 and AN-67 increases the range of the required mechanical properties. Composition and manufacturing technology has been developed for a new welding flux with application of slag from silicomanganese production. Fractional composition of the flux has been selected. A comparative assessment of the mechanical properties of the developed flux with widely used flux AN-348 (GOST 9087-81) showed that the mechanical properties of the new flux are much greater. It has been determined that the introduction of flux additive FD-UFS in the amount of 2-8 % significantly increases the value of toughness KCV at a temperature of minus 20 °C.

Abstract: Studied the effect of the introduction of vanadium and cobalt into the charge powder fused wire system Fe-C-Si-Mn-Cr-Ni-Mo-V, used in cladding assemblies and equipment parts and mechanisms operating under abrasive and abrasive shock loads. the cored wires samples were manufactured in the laboratory conditions and using appropriate powder materials and as a carbonfluoride contained material were used the dust from gas purification of aluminum production.

Abstract: The fluxing agent usually used to reduce the sintering temperature of ceramic production. In order to achieve this study, the potassium feldspar had used as a fluxing agent in range between 15.2 - 42.5 %. The mixture of slurry was formulated by using ball clay, silica, polyethylene glycol and potassium feldspar to produce the ceramic pieces. The sample was prepared by aging the mixed clay with additives and aging for 24 hours before casting on the flat mould to form rectangular ceramic pieces. The body pieces then undergo thermal treatment at temperature of 800C, 900°C, 1000°C, 1100°C and 1200°C for 2 hours with heating rate 5°C/min as to study the effect of flux towards sintering behavior of the samples. The characterization of the samples was conduct in order to study the chemical composition of sample. The effect of the fluxing agent towards sintering temperature was evaluated in order to investigate the firing shrinkage, density, porosity and water absorption. The result shows at temperature of 1100°C with increasing the amount of flux, the firing shrinkage decreasing from 18 to 13 %. Increasing the amount of flux had decrease the porosity and water absorption of ceramic pieces and the density of the ceramic pieces almost uniform. The optimum amount of flux was 42.5% and sintering temperature was 1100°C.

Abstract: The paper presents some aspects regarding the wetting conditions in aluminium – graphite composite. The wettability depends on several factors like the presence of the oxide skin at the melt surface, formation Al₄C₃ at the interface between Al and particles, temperature, pressure etc. In this paper, the conditions of perfect wettability of carbon by molten Al achieved under MCl–_K2TiF6 molten salts (fluxes), alloying of the melt with surface active elements, heat treatment of reinforcement material and coating of the particles with a metallic thin layer.

Abstract: Paper presents the main pollutants of the working environment at welding under flux, methodical determination which the main chemical reactions resulting in pollution and pollution coefficient calculation. A number of welding working regime in order to achieve a coefficient of minimal pollution. The experimental results demonstrate that the process of welding under flux is less polluting than manual arc welding and coated electrode but more polluting than the process of welding in protective gas environment. It shows the influence of welding regime parameters for the most important gas pollutants.

Abstract: Deep red emitting CaAl_12-xO₁₉:xMn⁴⁺ phosphors were synthesized by solid state reaction method. Various fluxes (BaF₂, H₃BO₃, Na₂CO₃ and NH₄Cl) were added in preparation of the phosphors. The influences of the various fluxes on the crystal structure, morphology and luminescent properties of CaAl₁₂O₁₉:Mn⁴⁺ phosphors were studied. The results show that the obtained phosphors with fluxes possessed better luminescent intensity than that of the phosphors without fluxes. The maximum luminescent intensities were found with the following order: H₃BO₃ (2.0 wt%) > Na₂CO₃ (0.5 wt%) > NH₄Cl (0.3 wt%) > BaF₂ (0.1 wt%) > no flux. The H₃BO₃ flux can decrease the single phase forming temperature of CaAl₁₂O₁₉:Mn⁴⁺ phosphors by about 150°C.

Abstract: The aim of this study was an investigation of the influence of technological parameters of the process of self-propagating high-temperature synthesis (SHS) on the formation of nanoparticles of titanium carbide from a mixture of powders of titanium and carbon in molten aluminum and on the properties of the obtained composite Al-10 wt. %TiC. The results show that the application of such techniques as the use of titanium powder of coarse fraction, the integrated flux of composition 30-35% NaCI, 52-57% KCI, 10-13% Na₂SiF₆ and adding aluminum powder to the initial charge can reduce the size of most of the synthesized particles of the carbide phase TiC to ultrafine sizes. At the same time, the replacement of 20% titanium metal powder in the charge with the titanium-containing salt Na₂TiF₆ makes it possible to synthesize nanoparticles of titanium carbide with size less than 0.1 μm in the composite Al-10%TiC. The produced SHS composite Al-10%TiC is characterized by a high level of physico-mechanical and tribological properties with good corrosion resistance. Reinforcement with ultrafine and nanosized particles of TiC enhances the strength characteristics of the composite Al-10%TiC by 2.5-2.9 times in comparison with pure aluminum, while the reinforcement with microsized particles of TiC (2-4 μm) only by 1.5-1.7 times; resistance to corrosion increases by 4-5 times.

Abstract: One of the considerations many power plants today is whether they can get more power out of their existing equipment especially generator. However, it is required design review and feasibility study in order to extend the operating life and increase the capability and reliability. In this study, analysis of magnetic field was performed due to power uprating in order to prevent a saturation of the magnetic field in the core laminate which can lead to the emergence of heat concentration. Based on the results of magnetic analysis using finite element, there are no saturation of the magnetic field in the core lamination which can lead to the magnetic saturation and heat concentration, both for existing and uprating conditions.Therefore, the increasing a design margin on the generators from the current design of the margin of 471,000 kVA to 494,550 kVA with the 0.85 power factor will not pose a problem as long as all of the following recommendations can be implemented. Although it is predicted, there will be no saturation and hotspots on the generator, but the risk of temperature rise due to the uprating should be reduced by replacing the stator winding using the Full Class F Insulation which is resistant to temperatures up to 155 °C.

Abstract: The paper considers the study of the electromagnetic force (EMF) of a synchronous generator based on the three-phase induction machine. The stand includes: a frequency converter, an induction motor, a synchronous generator, a three-phase rectifier, an active load resistance, power protection and inclusion industrial electrical network. The study provides an analytical solution to one of the main objectives within theoretical foundations of electrical engineering, formulated so to reflect the decision making while designing new types of synchronous generators with permanent magnets.