• Title/Summary/Keyword: Condensation control

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3D-based equivalent model of SMART control rod drive mechanism using dynamic condensation method

  • Ahn, Kwanghyun;Lee, Kang-Heon;Lee, Jae-Seon;Chang, Seongmin
    • Nuclear Engineering and Technology
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    • v.54 no.3
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    • pp.1109-1114
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    • 2022
  • The SMART (System-integrated Modular Advanced ReacTor) is an integral-type small modular reactor developed by KAERI (Korea Atomic Energy Research Institute). This paper discusses the feasibility and applicability of a 3D-based equivalent model using dynamic condensation method for seismic analysis of a SMART control rod drive mechanism. The equivalent model is utilized for complicated seismic analysis during the design of the SMART. While the 1D-based beam-mass equivalent model is widely used in the nuclear industry for its calculation efficiency, the 3D-based equivalent model is suggested for the seismic analysis of SMART to enhance the analysis accuracy of the 1D-based equivalent model while maintaining its analysis efficiency. To verify the suggested model, acceleration response spectra from seismic analysis based on the 3D-based equivalent model are compared to those from the 1D-based beam-mass equivalent model and experiments. The accuracy and efficiency of the dynamic condensation method are investigated by comparison to analysis results based on the conventional modeling methodology used for seismic analysis.

System Implementation for Dew Condensation Prevention of Distributing Boards based on the Dew Point (이슬 결로점 기반 수배전반 결로 방지 장치 제작)

  • Kim, Tae-Myoung;Jee, Suk-Kun;Kim, Young-Wan
    • Journal of IKEEE
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    • v.22 no.3
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    • pp.645-650
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    • 2018
  • IT-based automatic controller that control the temperature and humidity to prevent dew condensation of distributing board was designed and implemented in this paper. The dew condensation temperature was deduced from room temperature and humidity of distributing board. Based on the comparisons between the deduced dew condensation temperature and the temperature of surface condensation, the facilities that can prevent the condensation was implemented to be operated in due order. Also, the remote monitoring module to monitor operation status of controller was implemented using LoRa technique. The performances for controller operation and data transmission were validated from the transmission and operation test for dew condensation prevention. The controller can be put to good use at the facilities that requires the condensation prevention.

Enhancement of Condensation Heat Transfer of Anodized Aluminum by Teflon Coating and Oil-Impregnation (테플론 코팅과 오일 담지를 이용한 알루미늄 양극산화피막의 응축 열전달 향상)

  • Kang, Minjoo;Lee, Jonghoon;Cha, Soojin;Shin, Yeaji;Kim, Donghyun;Kim, Kyung-Ja;Lee, Junghoon
    • Journal of the Korean institute of surface engineering
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    • v.54 no.2
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    • pp.90-95
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    • 2021
  • Surface modification technique enabling the control of condensation provides various benefit in various engineering systems, such as heat transfer, desalination, power plants, and so on. In this study, lubricant oil-impregnation into Teflon-coated nanoporous anodic oxide layer of aluminum to enhance a de-wetting and mobility of water droplet on surface. Due to the surface treatment improving water-repellency, the condensation mode is changed to dropwise, thus the frequency of sliding condensed water droplet on surface is increased. For these reasons, the surface of oil-impregnated Teflon-coated nanoporous anodic aluminum oxide shows significantly enhanced condensation heat transfer compared to bare aluminum surface. In addition, the porosity of anodic aluminum oxide affected the mobility of water droplet even with oil-impregnation and Teflon-coating, indicating that the optimization of porous structure of anodic oxide is required for maximizing the condensation heat transfer.

A Study on the Application of the Dehumidification System for Radiant Floor Cooling Using Ondol (온돌을 이용한 바닥복사냉방의 제습시스템 적용에 관한 연구)

  • 임재한;여명석;양인호;김광우
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.7
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    • pp.607-616
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    • 2002
  • This study has been conducted to evaluate the applicability of the control method in the dehumidification-integrated radiant floor cooling system in terms of stability of the room air temperature and the control variables through experiments. To do this, the relationship between the control variables in preventing floor surface condensation is first analyzed and the control method is predetermined through simulations. The results are as follows. First, it is necessary to determine the operation status of the dehumidification system according to the relationship between floor surface temperature and dew point temperature in the conditioned space. Second, outdoor reset with indoor temperature feedback control is better than on/off bang-bang control with respect to temperature stability in controlling the room air temperature and the possibility of energy savings. Finally, the humidity sensor can be located with the current thermostat in that there are small differences in absolute humidity in vertical distribution.

Influence of the Inclination Angle and Liquid Charge Ratio on the Condensation in Closed Two-Phase Thermosyphons with Axial Internal Low-Fins

  • Cho, Dong-Hyun;Han, Kyu-il
    • Journal of Mechanical Science and Technology
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    • v.17 no.3
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    • pp.422-428
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    • 2003
  • This study concerns the performance of the heat transfer of the thermosyphons having 60, 70, 80. 90 axial internal low-fins in which boiling and condensation occurr. Water, HCFC-141b and CFC-11 have been used as the working fluids. The operating temperature, the liquid charge ratio and the inclination angle of thermosyphons have been used as the experimental parameters. The heat flux and heat transfer coefficient at the condenser are estimated from experimental results. The experimental results have been assessed and compared with existing theories. As a result of the experimental investigation, it was found that the maximum heat flow rate in the thermosyphons is dependent upon the liquid charge ratio and inclination angle. A relatively high rate of heat transfer has been achieved by the thermosyphon with axial internal low-fins. The inclination of a thermosyphon has a notable influence on the condensation. In addition, the overall heat transfer coefficients and the characteristics at the operating temperature are obtained for the practical applications.

Study on the efficient dynamic system condensation (동적 해석의 효율적 축소 기법에 관한 연구)

  • Baek, Sung-Min;Cho, Meang-Hyo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.631-636
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    • 2007
  • Eigenvalue reduction schemes approximate the lower eigenmodes that represent the global behavior of the structures. In the, we proposed a two-level condensation scheme(TLCS) for the construction of a reduced system. In first step, the of candidate elements by energy estimation, Rayleigh quotient, through Ritz vector calculation, and next, the primary degrees of freedom is selected by sequential elimination from the degrees of freedom connected the candidate elements in the first step. In the present study, we propose TLCS combined with iterative improved reduced system(IIRS) to increase accuracy of higher modes intermediate range. Also, it possible to control the accuracy of the eigenvalues and eigenmodes of the reduced system. Numerical examples demonstrate performance of proposed method.

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PASSlVE SHOCK CONTROL IN TRANSONIC FLOW FIELD

  • Matsuo S;Tanaka M;Setoguchi T;Kashimura H;Yasunobu T;Kim H.D
    • Journal of computational fluids engineering
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    • v.10 no.1
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    • pp.80-86
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    • 2005
  • In order to control the transonic flow field with a shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock-boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically. The result showed that the flow fields might be effectively controlled by the suitable combination between non-equilibrium condensation and the position of porous wall.

Passive Shock Control in Transonic Flow Field

  • Matsuo S.;Tanaka M.;Setoguchi T.;Kashimura H.;Yasunobu T.;Kim H. D.
    • 한국전산유체공학회:학술대회논문집
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    • 2003.10a
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    • pp.187-188
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    • 2003
  • In order to control the transonic flow field with shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock - boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically. The result showed that the flow fields might be effectively controlled by the suitable combination between non-equilibrium condensation and the position of porous wall.

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Development of a warning algorithm and monitoring system for preventing condensation in utility tunnels (공동구 내 결로 예방을 위한 경고 알고리즘 및 모니터링 시스템 개발)

  • Sang-Il Choi;Jung-Hun Kim;Suk-Min Kong;Yoseph Byun;Seong-Won Lee
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.26 no.5
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    • pp.551-561
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    • 2024
  • Underground utility tunnels are spaces densely packed with various infrastructure facilities, such as power, telecommunications, and water supply and drainage systems, making internal environment management crucial. An investigation into accident cases and on-site demands in these tunnels revealed that while fires and floods are the most common types of incidents, the demand for real-time condensation prevention and response is frequent according to on-site managers. Condensation occurs due to the difference in humidity and temperature between the inside and outside of the tunnel. Frequent or prolonged condensation can lead to metal pipe corrosion, electrical failures, and reduced equipment lifespan. Therefore, this study developed a control algorithm and monitoring system to prevent condensation in underground utility tunnels. The proposed control algorithm estimates the likelihood of condensation in real-time based on the measured temperature and humidity and suggests appropriate responses for each stage to the managers. Finally, a practical condensation prevention monitoring system was built based on the developed algorithm, verifying the feasibility and applicability of this technology in the field.

Analysis on Surface Temperature Control of an Insulated Vertical Wall Under Thermal Radiation Environment (단열재가 부착된 수직벽 표면의 온도제어 해석)

  • Kang, Byung-Ha;Pi, Chang-Hun;Kim, Suk-Hyun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.4
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    • pp.323-329
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    • 2012
  • In this study, a rational procedures for estimation of insulation thickness of a vertical wall for condensation control or personnel protection has been investigated. Design parameters are height of the wall, thermal conductivity, emissivity, and operating temperatures. The results indicated that the surface emissivity plays a very important role in the design of insulation for the purpose of surface temperature control, especially in natural convection situation. radiation heat transfer coefficients for some new insulation material surface, such as elastomers, estimated to be more than 90% of the total surface heat transfer coefficient.