• Title/Summary/Keyword: 증기 유량

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$MoS_2$ 박막 증착을 위한 Mo 전구체 특성 평가

  • Mun, Ji-Hun;Park, Myeong-Su;Yun, Ju-Yeong;Gang, Sang-U;Sin, Jae-Su;Lee, Chang-Hui;Kim, Tae-Seong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.252-252
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    • 2013
  • 최근 그래핀, hexagonal boron nitride (h-BN) 및 $MoS_2$ (molybdenum disulfide)와 같은 2차원 결정 물질들은 무어의 법칙(Moore's Law)를 뛰어넘어 계속적인 소자의 소형화를 가능케 하고 또한 대면적, 저비용 소자 개발을 가능케 하는 우수한 특성을 가진 차세대 반도체 트랜지스터 소재로 각광받고 있다. $MoS_2$는 bulk 상태일 때는 1.2 eV의 indirect 밴드갭을 가지지만 단층형태일 때는 1.8 eV의 direct 밴드갭을 가지며 dielectric screening 기법등을 통해 mobility를 향상시킬 수 있는 것으로 연구된 바 있다. 본 연구에서는 화학기상증착 (chemical vapor deposition)법을 이용하여 $MoS_2$ 박막을 형성하기 위한 기초연구인 Mo 전구체의 특성평가 및 적합한 공정조건 개발 연구를 수행하였다. 사용한 전구체는 $Mo(CO)_6$ (Molybdenum hexacarbonyl)이고, 온도 및 압력, 반응기체(H2 S, Hydrogen sulfide) 유량 등의 공정 조건 변화에 따른 거동을 Fourier transform infrared spectroscopy (FT-IR) 시스템을 사용하여 측정하였다. 또한 $Mo(CO)_6$의 분자구조를 상용 프로그램인 Gaussian으로 시뮬레이션 하여 실제 FT-IR 측정 결과값과 비교 분석하였다.

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Experimental Study of Air-cooled Condensation in Slightly Inclined Circular Tube (경사진 원형관에서의 공냉응축에 관한 실험적 연구)

  • Kim, Dong Eok;Kwon, Tae-Soon;Park, Hyun-Sik
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.4
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    • pp.29-34
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    • 2016
  • In this study, the experimental investigation of air-cooled condensation in slightly inclined circular tubes with and without fins has been conducted. In order to assess the effects of the essential parameters, variable air velocities and steam mass flow rates were given to the test section. The heat transfer performance of air-cooled condensation were dominantly affected by the air velocity, however, the increase of the steam mass flow rate gave relatively weaker effects to total heat transfer capability. And in the experimental cases with the finned tube, the total heat transfer rate of the finned tube was significantly larger than that of the flat tube. From those results, it can be confirmed that the most important parameter for air-cooled condensation heat transfer is the convective heat transfer characteristics of air. Therefore, for the well-designed long-term cooling passive safety system, the consideration of the optimal design of the fin geometry is needed, and the experimental and numerical validations of the heat transfer capability of the finned tube would be required.

Effect of Heat-Treatment in Se Atmosphere on the Densification of Absorber Layer Using $Cu(In,\;Ga)Se_2$ Nanoparticles ($Cu(In,\;Ga)Se_2$ 나노입자을 이용한 광흡수층 치밀화에 따른 Se 분위기의 열처리 효과)

  • Yoon, Kyung-Hoon;Kim, Ki-Hyun;Ahn, Se-Jin;Ahn, Byung-Tae
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.06a
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    • pp.210-213
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    • 2006
  • 나노입자를 이용하여 치밀한 $Cu(In,\;Ga)Se_2$ 태양전지용 광흡수층을 제조하기 위해 먼저, 콜로이달 방법으로 합성된 20nm이하의 CIGS 나노입자를 저가의 스프레이 법을 이용하여 CIGS 막을 제조하였다. 제조된 CIGS막을 two-zone RTP (rapid temperature Process) 방법으로 Se 분위기 안에서 열처리를 행하였다. 입자의 치밀화를 위해 기판의 온도, Se 증발온도와 수송가스의 유량을 조절하여 CIGS 입자성장을 행하였다. 그러나, Se의 증발온도가 높을수록 CIGS와 MO 박막 사이에서 $MoSe_2$ 층이 형성되었다. 형성된 $MoSe_2$층의 부피 팽창으로 인해 하부의 유리기판과 Mo층 사이에서 peeling off 현상이 발생했다. 이러한 Peeling off현상을 억제하면서 CIGS 나노입자 성장을 하기 위해, Se 공급을 빨리 할 수 있도록 Se의 증기압을 높였으며, 최적조건에서 급속 열처리 공정을 통해 CIGS 나노입자 성장과 치밀화를 위한 소결거동을 관찰하였다.

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A Study on the Uniform Distribution of Steam Flow in the Superheater Tube System (과열기 관군에서의 증기유량 균일 배분 연구)

  • Park, Ho-Young;Kim, Sung-Chul
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.6
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    • pp.416-426
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    • 2008
  • The boiler tube failure often experienced in the superheater of a utility boiler can seriously affect the economic and safe operation of the power plant. It has been known that this failure is mainly caused by the thermal load deviation in the superheater tube system, and deeply intensified by the non-uniform distribution of steam flow rates. The nonuniform steam flow is distinctively prominent at low power load rather than at full power load. In this paper, we analyze the steam flow distribution in the superheater tube system by using one dimensional flow network model. At 30% power load, the deviation of steam flow rate is predicted to be within 0.8% of the averaged flow rate. This deviation can be reduced to 0.1% and 0.07% by assuming two cases, that is, the removal of 13th tube at each tube rows and the installation of intermediate header, respectively. The assumed two cases would be effective for the uniform steam flow distribution across 85 superheater tube rows.

A Debris Bed Model with Gab Inflow and Gas Upflow for Debris/Water/Concrete Interaction and Its Application under Severe Accident Condition in LWR. (개스 Inflow와 Upflow를 갖는 Debris/water/concrete상호작용 해석용 Debris Bed 모델 및 중대사고 조건에 그 적용해석)

  • Jong In Lee;Jin Soo Kim;Byung Hun Lee
    • Nuclear Engineering and Technology
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    • v.17 no.1
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    • pp.8-15
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    • 1985
  • A model for thermal interactions of debris/water with gas flow from within and below debris bed was presented for severe accident analysis in LWR. The consumption of steam, production of hydrogen in the debris bed, generation of gases from below debris bed and generation of chemical heat are included in the conservation equations. The model has been incorporated in the MARCH code to estimate the gas production due to both metal/oxidation and hot debris/concrete interaction. The results indicate that the hydrogen source can potentially give a significant impact on the containment pressure transient and the conductive heat loss to concrete and the convective gas cooling in the debris bed have a small effect on the debris bed coolability. However, the reheating and melting of the debris particles could be delayed by the interaction of debris with concrete.

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Laboratory Tests for Trichloroethylene (TCE) and Toluene Remediation in Soil Using Soil Vapor Extraction (토양증기추출(Soil Vapor Extraction)을 이용한 토양 내 Trichloroethylene (TCE)과 Toluene정화 실험)

  • 이민희;강현민
    • Economic and Environmental Geology
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    • v.35 no.3
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    • pp.221-227
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    • 2002
  • Column experiments were performed to evaluate the removal efficiency of soil vapor extraction (SVE) iota TCE (trichloroethylene) and toluene in soil. Homogeneous Ottawa sands and real soils collected from contaminated area were used to investigate the effect of soil properties and SVE operation conditions on the removal efficiency. In column teats with two different sizes of Ottawa sand, the maximum effluent TCE concentration in a coarse sand column was 442 mg/L and 337 mg/L in a fine sand column. However, after 20 liter gas flushing, the effluent concentrations were very similar and more than 90% of initial TCE mass were removed from the column. For two real contaminated soil columns, the maximum effluent concentration decreased 50% compared with that in the homogeneous Ottawa coarse sand column, but 99% of initial TCE mass were extracted from the column within 40 liter air flushing, suggesting that SVE is very available to remove volatile NAPLs in the contaminated soil. To investigate the effect of contaminant existing time on the removal efficiency, an Ottawa sand column was left stable for one week after TCE was injected and the gas extraction was applied into the column. Its effluent concentration trend was very similar to those for other Ottawa sand columns except that the residual TCE after the air flushing showed relatively high. Column tests with different water contents were performed and results showed high removal efficiency even in a high water content sand column. Toluene as one of BTEX compounds was used in an Ottawa sand column and a real soil column. Removal trends were similar to those in TCE contaminated columns and more than 98% of initial toluene mass were removed with SVE in both column.

A Study on the CO2 Removal Efficiency with Aqueous MEA and Blended Solutions in a Vortex Tube Type Absorber (Vortex Tube 형 흡수장치에서 MEA와 혼합흡수용액을 이용한 CO2 제거 효율 고찰)

  • Ryu, Woo-Jung;Han, Keun-Hee;Choi, Won-Kil;Lee, Jong-Sub;Park, So-Jin
    • Korean Chemical Engineering Research
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    • v.47 no.6
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    • pp.795-800
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    • 2009
  • In this study, the $CO_2$ removal characteristics of the Vortex tube type absorbtion apparatus were investigated to enhance the compactness of $CO_2$ absorption process and to reduce the amount of absorbing solution of the $CO_2$ separation process. The Vortex tube with the diameter of 17 mm and the length of 250mm was introduced in the experimental apparatus to treat $20Nm^3/hr$ of $CO_2$ containing flue gas. The flue gases for experiments containing 11~13 vol% of $CO_2$ were supplied from the coal-firing CFBC power plant with 12 ton/hr of steam producing capacity. The mixed solutions of 20 wt% of MEA as base solution with the adding solutions like HMDA, AMP and KOH were used as absorbents. The experiments were executed under the various conditions like the absorbing solution concentrations in the range of 20 to 50 wt%, the flow rate of $CO_2$ containing flue gases in the range of 6 to $15Nm^3/hr$ and the flow rate of absorbing solution in the range of 1.0 to 3.0 l/min. As a results, the $CO_2$ removal efficiency of mixed absorbent of 20 wt% of MEA with HMDA was remarkable. From this study, we concluded that the efficient separation of $CO_2$ from flue gases using the features of the Vortex tube type absorbing unit for gas/liquid contact and the separation of gas/liquid be possible. But more works are needed to increase the $CO_2$ removal efficiency of Vortex tube process.

An Experimental Study on Flow Distributor Performance with Single-Train Passive Safety System of SMART-ITL (SMART-ITL 1 계열 피동안전계통을 이용한 유동분사기 성능에 대한 실험연구)

  • Ryu, Sung Uk;Bae, Hwang;Yang, Jin Hwa;Jeon, Byong Guk;Yun, Eun Koo;Kim, Jaemin;Bang, Yoon Gon;Kim, Myung Joon;Yi, Sung-Jae;Park, Hyun-Sik
    • Journal of Energy Engineering
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    • v.25 no.4
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    • pp.124-132
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    • 2016
  • In order to estimate the effect of flow distributors connected to an upper nozzle of CMT(Core Makeup Tank) on the thermal-hydraulic characteristics in the tank, a simplified 2 inch Small Break Loss of Coolant Accident(SBLOCA) was simulated by skipping the decay power and Passive Residual Heat Removal System(PRHRS) actuation. The CMT is a part of safety injection systems in the SMART (System Integrated Modular Advanced Reactor). Each test was performed with reliable boundary conditions. It means that the pressure distribution is provided with repeatable and reproducible behavior during SBLOCA simulations. The maximum flow rates were achieved at around 350 seconds after the initial opening of the isolation valve installed in CMT. After a short period of decreased flow rate, it attained a steady injection flow rate after about 1,250 seconds. This unstable injection period of the CMT coolant is due to the condensation of steam injected into the upper part of CMT. The steady injection flow rate was about 8.4% higher with B-type distributor than that with A-type distributor. The gravity injection during hot condition tests were in good agreement with that during cold condition tests except for the early stages.

Production of Fluorosilicic Acid from Phosphoric Acid Slurry of a Fertilizer Manufacturing Plant (비료공장의 인산 슬러리로부터 규불산 제조)

  • Kim, Se-Won;Moon, Woo-Kyun;Park, Hung-Suck
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.2
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    • pp.926-933
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    • 2012
  • Phosphoric acid used for the production of phosphate fertilizers is synthesized by the reaction of phosphate rock and sulfuric acid. As the reaction is exothermic, yield of phosphoric acid is poor at elevated temperature. Therefore, enhancement in its yield requires the process temperature be maintained by releasing the vapor ($80^{\circ}C$) containing HF and SiF4 through a vacuum cooler. However, these valuable resources; Fand Si, which can be utilized for the manufacture of refrigerant and polysilicon, respectively, are being wasted in the treatment process. We performed lab-scale experiments to estimate the amount of recoverable H2SiF6, a by-product of phosphoric acid manufacturing process. The experimental results showed a decrease of fluorine concentration by 0.12wt% in the liquid phase. Preliminary estimation showed a possible recovery of 5,509 ton/yr of fluorine considering the scale of the fertilizer manufacturing plant. Furthermore, field-scale experiment showed that H2SiF6 could be enriched in liquid phase from 0.35wt% to 7.33wt% and the vapor flow-rate from vacuum cooler was estimated at $51,000m^3/hr$. Anew, the efficiency of fluorine recovery in the pilot-scale experiment was found to be 76.74% and the production of H2SiF6 was estimated at 5,340 ton/yr.

Comparison Of CATHARE2 And RELAP5/MOD3 Predictions On The BETHSY 6.2% TC Small-Break Loss-Of-Coolant Experiment (CATHARE2와 RELAP5/MOD3를 이용한 BETHSY 6.2 TC 소형 냉각재상실사고 실험결과의 해석)

  • Chung, Young-Jong;Jeong, Jae-Jun;Chang, Won-Pyo;Kim, Dong-Su
    • Nuclear Engineering and Technology
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    • v.26 no.1
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    • pp.126-139
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    • 1994
  • Best-estimate thermal-hydraulic codes, CATHARE2 V1.2 and RELAP5/MOD3, hate been assessed against the BETHSY 6.2 tc six-inch cold leg break loss-of-coolant accident (LOCA) test. Main objective is to analyze the overall capabilities of the two codes on physical phenomena of concern during the small break LOCA i.e. two-phase critical flow, depressurization, core water level de-pression, loop seal clearing, liquid holdup, etc. The calculation results show that the too codes predict well both in the occurrences and trends of major two-phase flow phenomena observed. Especially, the CATHARE2 calculations show better agreements with the experimental data. However, the two codes, in common, show some deviations in the predictions of loop seal clearing, collapsed core water level after the loop seal clearing, and accumulator injection behaviors. The discrepancies found from the comprision with the experimental data are larger in the RELAP5 results than in the CATHARE2. To analyze the deviations of the two code predictions in detail, several sensitivity calculations have been performed. In addition to the change of two-phase discharge coefficients for the break junction, fine nodalization and some corrections of the interphase drag term are made. For CATHARE2, the change of interphase drag force improves the mass distribution in the primary side. And the prediction of SG pressure is improved by the modification of boundary conditions. For RELAP5, any single input change doesn't improve the whole result and it is found that the interphase drag model has still large uncertainties.

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