• Title/Summary/Keyword: Gas condensation method

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IMPROVEMENTS OF CONDENSATION HEAT TRANSFER MODELS IN MARS CODE FOR LAMINAR FLOW IN PRESENCE OF NON-CONDENSABLE GAS

  • Bang, Young-Suk;Chun, Ji-Ran;Chung, Bub-Dong;Park, Goon-Cherl
    • Nuclear Engineering and Technology
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    • v.41 no.8
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    • pp.1015-1024
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    • 2009
  • The presence of a non-condensable gas can considerably reduce the level of condensation heat transfer. The non-condensable gas effect is a primary concern in some passive systems used in advanced design concepts, such as the Passive Residual Heat Removal System (PRHRS) of the System-integrated Modular Advanced ReacTor (SMART) and the Passive Containment Cooling System (PCCS) of the Simplified Boiling Water Reactor (SBWR). This study examined the capability of the Multi-dimensional Analysis of Reactor Safety (MARS) code to predict condensation heat transfer in a vertical tube containing a non-condensable gas. Five experiments were simulated to evaluate the MARS code. The results of the simulations showed that the MARS code overestimated the condensation heat transfer coefficient compared to the experimental data. In particular, in small-diameter cases, the MARS predictions showed significant differences from the measured data, and the condensation heat transfer coefficient behavior along the tube did not match the experimental data. A new method for calculating condensation heat transfer coefficient was incorporated in MARS that considers the interfacial shear stress as well as flow condition determination criterion. The predictions were improved by using the new condensation model.

A study on effect of heat transfer of condensation including noncondensable gas over a flat plate (불응축가스가 평판위 응축열전달에 미치는 영향에 관한 연구)

  • 양대일;정형호
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.1
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    • pp.25-30
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    • 2000
  • In present paper, mass transfer over a flat plate with film condensation including noncondesable gas is analyzed with the help of similarity methods. Couette flow was assumed in liquid film and boundary-layer approximation was used in the ambient flow. Governing equations were transformed into the ordinary differential equtions by the similarity methods. Runge-Kutta and shooting method were used in order to fine the effect of mass transfer on the velocity and concentrations at the liquid-vapor interface.

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Construction and Evaluation of $O_3$ Condensation System for Oxide Thin Film (산화 박막 성장을 위한 $O_3$ 농축 시스템의 구축 및 평가)

  • Lim, Jung-Kwan;Ryu, Sun-Jong;Park, Yong-Pil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.1192-1195
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    • 2003
  • A highly condensed ozone gas be transferred to the superconductor thin film growth chamber because ozone is strong oxidizing gas. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper an ozone condensation system was evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone was condensed by an adsorption method and the ozone concentration reached 8.5 mol% in 2.5 h after the beginning of the ozone condensation process, indicating high effectiveness of the condensation process. Ozone was continuously desorbed from the silica gel by the negative pressure.

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Processing of Tin Oxide Nanoparticles by Inert Gas Condensation Method and Characterization

  • Simchi, Abdolreza;Kohi, Payam
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.122-123
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    • 2006
  • Tin oxide nanoparticles (n-SnO and $n-SnO_2$) were synthesized by the inert gas condensation (IGC) method under dynamic gas flow of oxygen and argon at various conditions. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) method were used to analysis the size, shape and crystal structure of the produced powders. The synthesized particles were mostly amorphous and their size increased with increasing the partial pressure of oxygen in the processing chamber. The particles also became broader in size when higher oxygen pressures were applied. Low temperature annealing at $320^{\circ}C$ in air resulted to crystallization of the amorphous n-SnO particles to $SnO_2$.

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Characteristics of dry-process based metal nano ink for printed electrodes

  • Kim, Dong-Kwon;Lee, Caroline;Hong, Seong-Je;Kim, Young-Seok
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.1466-1468
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    • 2009
  • The preparation method of copper nanopowder by dry process for conductive ink was investigated. Inert gas condensation method was used to synthesize copper nanopowder. The produced powders was spherical and sized 10~100nm flowing the conditions. The results showed that input voltage and evaporation rate is critical variables for nano-sized copper powder.

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Size Control of Bismuth Nanoparticles by Changes in Carrier-Gas Flow Rate and Chamber Pressure of Gas Condensation Apparatus (가스응축장치 캐리어가스 공급속도 및 압력변화를 통한 비스무스 나노분말 입도제어)

  • Lee, Gyoung-Ja;Kim, Chang-Kyu;Lee, Min-Ku;Rhee, Chang-Kyu
    • Journal of Powder Materials
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    • v.17 no.5
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    • pp.379-384
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    • 2010
  • In the present work, bismuth nanopowders with various particle size distributions were synthesized by controlling argon (Ar) gas flow rate and chamber pressure of a gas condensation (GC) apparatus. From the analyses of transmission electron microscopy (TEM) images and nitrogen gas adsorption results, it was found that as Ar gas flow rate increased, the specific surface area of bismuth increased and the average particles size decreased. On the other hand, as the chamber pressure increased, the specific surface area of bismuth decreased and the average particles size increased. The optimum gas flow rate and chamber pressure for the maximized electrochemical active surface area were determined to be 8 L/min and 50 torr, respectively. The bismuth nanopowders synthesized at the above condition exhibit 13.47 $m^2g^{-1}$ of specific surface area and 45.6 nm of average particles diameter.

Evaluation of Oxidation System for Metal Oxide Thin Film (금속 산화물 박막 제작을 위한 산화 시스템의 평가)

  • Lim, Jung-Kwan;Ryu, Sun-Jong;Park, Yong-Pil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05d
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    • pp.25-28
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    • 2003
  • Ozone is a strong and useful oxidizing gas for the fabrication of oxide thin films. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper an ozone condensation system was evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone was condensed by an adsorption method and the ozone concentration reached 8.5 mol% in 2.5 h after the beginning of the ozone condensation process, indicating high effectiveness of the condensation process. Ozone was continuously desorbed from the silica gel by the negative pressure. We found the decomposition in the ozone concentration negligible if the condensed ozone is transferred from the ozone condensation system to the film growth chamber within a few minutes.

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Superhydrophobic Surfaces for condensation by using spray coating method

  • Oh, Seungtae;Seo, Donghyun;Lee, Choongyeop;Nam, Youngsuk
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.157.2-157.2
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    • 2016
  • Water repellent surfaces may enhance the condensation by efficiently removing the condensed droplets. However, such surfaces may lose their original performance as they are exposed to external mechanical stresses. In this work, we fabricated spray-coated mechanically robust superhydrophobic surfaces using treated titanium dioxide (Type 1) or silica particles (Type 2). Then we compared the mechanical robustness of such surfaces with the silane-coated superhydrophobic surface and PEEK coated surface using a controlled-sand blasting method. The results show that the spray-coated samples can maintain the same level of the contact angle hysteresis than silane-coated superhydorphobic surface after sand blasting at 2 bar. The spray-coating method was applied to the tube type condenser and the condensation behaviors were observed within the environmental chamber with controlled pressure, humidity and non-condensable gas. Previously-reported droplet jumping was observed in the early stage of the condensation event, but soon the droplet jumping stopped and only dropwise condensation was observed since the condensed droplets were pinned on the cracks at spray-coated surfaces. The static contact angle decreases from $158.0^{\circ}$ to $133.2^{\circ}$, and hysteresis increases from $3.0^{\circ}$ to $23.5^{\circ}$ when active condensation occurs on such surfaces. This work suggests the benefits and limitation of spray-coated superhydrophobic condensers and help develop advanced condensers for practical use.

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Construction and Evaluation of Oxidation System for Superconductor Thin Film (초전도 박막 제작을 위한 산화 시스템 구축 및 평가)

  • 임중관;박용필;송경용
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.2
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    • pp.163-167
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    • 2003
  • Ozone is strong and useful oxidizing gas for the fabrication of oxidation thin films. In order to obtain high quality thin film, the ozone concentration must be increased. An ozone condensation system is evaluated in the viewpoint of an ozone supplier for oxidation thin film growth. Ozone is condensed by the adsorption method and ozone concentration reaches 8.5 mol% by 2.5 h after the beginning of the ozone condensation is negligible if the condensed ozone is transferred between the ozone condensation system and the film growth chamber within a few minutes. CuO peak which is the result of the obtained Cu-films using condensed ozone appears by XRD patterns.