• Title/Summary/Keyword: Fuel Particles

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Influences of heating processes on properties and microstructure of porous CeO2 beads as a surrogate for nuclear fuels fabricated by a microfluidic sol-gel process

  • Song, Tong;Guo, Lin;Chen, Ming;Chang, Zhen-Qi
    • Nuclear Engineering and Technology
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    • v.51 no.1
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    • pp.257-262
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    • 2019
  • The control of microstructure is critical for the porous fuel particles used for infiltrating actinide nuclides. This study concerns the effect of heating processes on properties and microstructure of the fuel particles. The uniform gel precursor beads were synthesized by a microfluidic sol-gel process and then the porous $CeO_2$ microspheres, as a surrogate for the ceramic nuclear fuel particles, were obtained by heating treatment of the gel precursors. The fabricated $CeO_2$ microspheres have a narrow size distribution and good sphericity due to the feature of microfluidics. The effects of heating processes parameters, such as heating mode and peak temperatures on the properties of microspheres were studied in detail. An optimized heating mode and the peak temperature of $650^{\circ}C$ were selected to produce porous $CeO_2$ microspheres. The optimized heating mode can avoid the appearance of broken or crack microspheres in the heating process, and as-prepared porous microspheres were of suitable pore size distribution and pore volume for loading minor actinide (MA) solution by an infiltration method that is used for fabrication of MA-bearing nuclear fuel beads. After the infiltration process, $1000^{\circ}C$ was selected as the final temperature to improve the compressive strength of microspheres.

OH Radical Distribution and Sooting Characteristics in Co-Flow Diffusion Flames (동축류 확산화염의 OH 라다칼 분포 및 매연 특성)

  • Lee, Won-Nam;Song, Young-Hoon;Cha, Min-Suk
    • 한국연소학회:학술대회논문집
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    • 1997.06a
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    • pp.1-11
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    • 1997
  • The soot and OH radical distributions have been experimentally studied in ethylene and propane laminar diffusion flames. The integrated soot volume fraction was measured along the centerline of a flame using a laser light extinction method. Planar laser light scattering and PLIF techniques are employed for the soot and OH radical distribution measurements utilizing Nd:YAG laser and OPO, FDO system. The concentration of OH radical is rapidly decreased at the edge of sooting region, which implies the importance of OH radical species on the soot oxidation process. For ethylene flames, the addition of air in fuel moves the OH radical distribution towards the center line of a flame at the soot oxidation region, while the concentration of OH radical remains relatively high at the soot formation region. The interaction between soot particles and OH radicals becomes more active with fuel-air at the soot oxidation region. For propane flames, however, any indication of the increased interaction between soot particles and OH radicals with fuel-air was not noticed.

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Role of Different Oxide to Fuel Ratios in Solution Combustion Synthesis of SnO2 Nanoparticles

  • Chavan, Archana U.;Kim, Ji-Hye;Im, Ha-Ni;Song, Sun-Ju
    • Journal of the Korean Ceramic Society
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    • v.53 no.1
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    • pp.122-127
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    • 2016
  • Tin oxide ($SnO_2$) nanoparticles have been synthesized by solution combustion method using citric acid as a fuel. The oxide to fuel ratio has been varied to obtain ultrafine nanoparticles with better surface area; such particles will be useful in many applications. With this synthesis method, spherical particles are formed having a particle size in the range of 11-30 nm and BET surface area of ~ $24m^2/g$. The degree of agglomeration of $SnO_2$ nanoparticles has been calculated.

Modeling of Combustion and Heat Transfer in the Iron Ore Sintering Bed (제철 소결기 베드 내 연소 및 열전달 모델링)

  • Yang, Won;Ryu, Chang-Kook;Choi, Sang-Min
    • Journal of the Korean Society of Combustion
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    • v.7 no.3
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    • pp.23-31
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    • 2002
  • Processes in an iron ore sintering bed can characterized as a relatively uniform progress of fuel, cokes combustion and complicated physical change of solid particles. The sintering bed was modelled as an unsteady one-dimensional progress of the fuel layer, containing two phases: solid and gas. Coke added to the raw mix, of which the amount is about 3.5% of the total weight, was assumed to form a single particle with other components. Numerical simulations of the condition in the iron ore sintering bed were performed for various parameters: moisture contents, cokes contents and air suction rates, along with the various particle diameters of the solid for sensitivity analysis. Calculation results showed that the influence of these parameters on the bed condition should be carefully evaluated, in order to achieve self-sustaining combustion without high temperature section. The model should be extended to consider the bed structural change and multiple solid phase, which could treat the inerts and fuel particles separately.

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Prediction of Combustion and Heat Transfer in the Sintering Bed of Iron Ore (제철 소결공정의 철광석-코크스 베드에서의 연소와 열전달 해석)

  • Yang, Won;Ryu, Chang-Kook;Choi, Sang-Min
    • 한국연소학회:학술대회논문집
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    • 2001.11a
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    • pp.161-168
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    • 2001
  • Sintering bed of iron ore in the steel making process is one of typical applications of solid fuel bed, which has relatively uniform progress of fuel and simple processes of combustion. The sintering bed was modelled as an unsteady one-dimensional progress of fuel layer containing the two phases of solid and gas. Cokes added to the raw mix of which the amount is about 3.5% of the total weight was assumed to form a single particle with other components. In the early predition results presented in this paper, the flame propagation within the bed was not sustained after the top surface of the bed was ignited with hot gas. It suggests that the model should be extended to consider the multiple solid phase, which can treat the ore particles and the coke particles separately.

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A Study on the Designation of Standard Solid Test Particles for Marine Centrifugal Purifier Performance Test (선박용 정유기 고형분 분리 성능시험 표준시료 지정에 관한 연구)

  • Jeong, Sang-Hu
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.6
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    • pp.804-809
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    • 2007
  • In order to provide reliability. reproducibility. objectivity of solid particle separation performance test on marine centrifugal purifier, an investigation had been done on solid test dusts. test standards and designation of a definite standard test dust In test specifications or standards. ISO 121031-1 A2 test dust is the best test particle to meet commercial and military fuel oil and lube oil requirements on marine standards.

Analyses of Size of Solidified Particles in Steam Explosions of Molten Core Material (원자로 물질의 증기폭발에서 고화 입자 크기 분석)

  • Park, Ik-Kyu;Kim, Jong-Hwan;Min, Beong-Tae;Hong, Seong-Wan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.12
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    • pp.1051-1060
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    • 2010
  • The effect of materials on fuel coolant interactions (FCIs) was analyzed on the basis of a solidified particle size response for TROI experiments.$^{(1)}$ The solidified particle size response can provide an understanding of the relationship among the initial condition, the mixing, and an explosion. Through a comparison of the size distributions of the solidified particles in the case of explosive and non-explosive FCIs, it is revealed that an explosive FCI results in the production of a large amount of fine particles and a small amount of large particles. The material effect of the size of solidified particles was analyzed using non-explosive FCIs without losing the information on the mixing. This analysis indicates that an explosive melt includes large particles that participate in the steam explosion, whereas a nonexplosive melt includes smaller particles and finer particles.

Natural Gas Combustion Characteristics of Mass Produced Oxygen Carrier Particles for Chemical-looping Combustor in a Batch Type Fluidized Bed Reactor (회분식 유동층 반응기에서 매체순환식 가스연소기용 대량생산 산소공여입자들의 천연가스 연소특성)

  • Ryu, Ho-Jung;Kim, Kyung-Su;Park, Yeong-Seong;Park, Moon-Hee
    • Transactions of the Korean hydrogen and new energy society
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    • v.20 no.2
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    • pp.151-160
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    • 2009
  • Natural gas combustion characteristics of mass produced oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor. Five particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN703-950, OCN703-1100 were used as oxygen carrier particles. Natural gas and air were used as reactants for reduction and oxidation, respectively. During reduction reaction, high fuel conversion and high $CO_2$ selectivity were achieved for most of oxygen carriers. During oxidation, NO emission was very low. These results indicate that inherent $CO_2$ separation and low NOx combustion are feasible for the natural gas fueled chemical-looping combustion system. Among the five oxygen carriers, OCN703-1100 particle was selected as the best candidate for demonstration of long-term operation in large-scale chemical-looping combustor from the viewpoints of fuel conversion, $CO_2$ selectivity, $CH_4$ concentration, and CO concentration.

Effects of the Counter Ion Valency on the Colloidal Interaction between Two Cylindrical Particles

  • Lee, In-Ho;Dong, Hyun-Bae;Choi, Ju-Young;Lee, Sang-Yup
    • Bulletin of the Korean Chemical Society
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    • v.30 no.3
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    • pp.567-572
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    • 2009
  • In this study, the effects of counter ion valency of the electrolyte on the colloidal repulsion between two parallel cylindrical particles were investigated. Electrostatic interactions of the cylindrical particles were calculated with the variation of counter ion valency. To calculate the electrical repulsive energy working between these two cylindrical particles, Derjaguin approximation was applied. The electrostatic potential profiles were obtained numerically by solving nonlinear Poission-Boltzmann (P-B) equation and calculating middle point potential and repulsive energy working between interacting surfaces. The electrical potential and repulsive energy were influenced by counter ion valency, Debye length, and surface potential. The potential profile and middle point potential decayed with the counter ion valency due to the promoted shielding of electrical charge. On the while, the repulsive energy increased with the counter ion valency at a short separation distance. These behaviors of electrostatic interaction agreed with previous results on planar or spherical surfaces.