• Title/Summary/Keyword: Coolant Flow Rate

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Characterization Tests on the SIT Injection Capability of the ATLAS for an APR1400 Simulation (APR1400 모의를 위한 ATLAS 안전주입탱크의 주입 성능에 관한 특성 시험)

  • Park, Hyun-Sik;Choi, Nam-Hyun;Park, Choon-Kyung;Kim, Yeon-Sik
    • Journal of Energy Engineering
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    • v.17 no.2
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    • pp.67-76
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    • 2008
  • A thermal-hydraulic integral effect test facility, ATLAS (Advanced Thermal-hydraulic Test Loop for Accident Simulation), has been constructed at KAERI (Korea Atomic Energy Research Institute). Recently several integral effect tests for the reflood period of a LBLOCA (Large Break LOss of Coolant Accident) of the APR1400 have been performed with the ATLAS. In the APR1400 a high flow condition is changed to a low flow condition due to an fluidic device during an operation of the SIT. As the self-controlled fluidic device was not installed in the ATLAS, a set of characterization tests was performed to simulate its injection capability from the SIT for the APR1400 simulation. In the ATLAS the required SIT flow rate in the high flow condition was acquired by installing orifices with an optimized flow area to throttle the SIT discharge line and the low flow condition was achieved by changing the opening of the flow control valve in the SIT injection line. The test results showed that the safety injection systems of the ATLAS could simulate the required high and low flow rates of the SIT for the APR1400 simulation efficiently.

Air-side Heat Transfer and Pressure Drop of a Fin-and-Tube Heat Exchanger Under Low Temperature Condition (저온 조건에서 핀-관 열교환기의 공기측 열전달 및 압력손실)

  • Kim, Nae-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.4
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    • pp.15-20
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    • 2017
  • Currently, residential air conditioners operate as a heat pump during winter. In this case, the outdoor heat exchanger acts as an evaporator obtaining heat from cold air. On the other hand, it acts as a condenser during summer transferring heat to hot air. The outdoor temperature changes significantly from high to low. Generally, the air-side j and f factors are obtained at a standard outdoor temperature. Therefore, the applicability of the j and f factors under different outdoor conditions needs to be checked. In this study, tests were conducted for a two-row louver finned heat exchanger changing the outdoor temperature to subzero. The effects of the tube-side brine flow rate were also checked. The results showed that air-side j and f factors were essentially constant and independent of the outdoor temperature, suggesting that an extension of j and f factors obtained under standard conditions to a low outdoor temperature is acceptable. All j and f factors agreed within 9% and 3%, respectively. Tests were also conducted by changing the coolant flow rate. Both the j and f factors did not change according to the flow rate, suggesting that the tube-side heat transfer correlation is acceptable.

Numerical Study on the Cooling Characteristics of a Passive-Type PEMFC Stack (수동공기공급형 고분자 전해질 연료전지 스택에서의 냉각특성에 대한 전산해석 연구)

  • Lee, Jae-Hyuk;Kim, Bo-Sung;Lee, Yong-Taek;Kim, Yong-Chan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.8
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    • pp.767-774
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    • 2010
  • In a passive-type PEMFC stack, axial fans operate to supply both oxidant and coolant to cathode side of the stack. It is possible to make a simple system because the passive-type PEMFC stack does not require additional cooling equipment. However, the performance of a cooling system in which water is used as a coolant is better than that of the air-cooling system. To ensure system reliability, it is essential to make cooling system effective by adopting an optimal stack design. In this study, a numerical investigation has been carried out to identify an optimum cooling strategy. Various channel configurations were applied to the test section. The passive-type PEMFC was tested by varying airflow rate distribution at the cathode side and external heat transfer coefficient of the stack. The best cooling performance was achieved when a channel with thick ribs was used, and the overheating at the center of the stack was reduced when a case in which airflow was concentrated at the middle of the stack was used.

Development of Hard-wired Instrumentation and Control for the Neutral Beam Test Facility at KAERI

  • Jung Ki-Sok;Yoon Byung-Joo;Yoon Jae-Sung;Seo Min-Seok
    • Journal of Electrical Engineering and Technology
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    • v.1 no.3
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    • pp.359-365
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    • 2006
  • Since the start of the KSTAR (Korea Superconducting Tokamak Advanced Research) project, Instrumentation and Control (I&C) of the Neutral Beam Test Facility (NB-TF) has been striving to answer diverse requests arising from various facets during the project's development and construction phases. Hard-wired electrical circuits have been designed, tested, fabricated, and finally installed to the relevant parts of the system. In relation to the vacuum system I&C, controlling functions for the rotary pumps, a Roots pump, two turbomolecular pumps, and four cryosorption pumps have been constructed. I&C for the ion source operation are the temperature and flow rate signal monitoring, Langmuir probe signal measurements, gradient grid current measurements, and arc detector circuit. For the huge power system to be monitored or safely operated, many temperature measurement functions have also been implemented for the beam line components like the neutralizer, bending magnet, ion dump, and calorimeter. Nearly all of the control and probe signals between the NB test stand and the control room were made to be transmitted through the optical cables. Failures of coolant flow or beam line vacuum pressure were made to be safely blocked from influencing the system by an appropriate interlock circuit that will shut down the extraction voltage application to the system or prevent damages to the vacuum components. Preliminary estimation of the beam power through the calorimetric measurement shows that 87.9% of the total power of the 60kV/18A beam with 200 seconds duration is absorbed by the calorimeter surface. Most of these I&C results would be highly appropriate for the construction of the main NBI facility for the KSTAR national fusion research project.

Study on Heat Transfer Characteristic in Combustor Nozzle (연소기 노즐에서의 열전달 특성 연구)

  • NamKoung, Hyuck-Joon;Kim, Hwa-Jung;Han, Poong-Gyoo;Lee, Kyoung-Hun;Kim, Young-Soo;Jeong, Hae-Seung;Lee, Sang-Youn
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.11a
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    • pp.34-40
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    • 2006
  • For a cooling performance research of the combustor operated in a extreme environment of a high temperature and high pressure, we accomplished a cooling performance analysis. Generally a heat transfer characteristic in cooling passage is known well experimentally and theoretically, however heat flux in the combustion chamber isn't. In this study, fluid flow combined with heat transfer and thermal structural analysis is accomplished about a combustor nozzle. We tried to analyze the cooling performance with a heat transfer characteristic of a gas and coolant side in the view point of quantity on the mass flow rate to be supplied to the cooling channel. And finally, evaluation on the thermal and structural safety of nozzle wall material was accomplished.

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A Study on Finned Tube Used in Turbo Refrigerator(III) -for Pressure Drop- (터보 냉동기용 핀 튜브에 관한 연구 (III) -압력 손실에 관하여-)

  • Han, Kyu-Il;Kim, Si-Young;Cho, Dong-Hyun
    • Journal of Fisheries and Marine Sciences Education
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    • v.6 no.1
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    • pp.58-76
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    • 1994
  • Heat transfer and pressure drop measurements are made on low integral-fin tubes in turbulent water flow condition. The integral-fin tubes investigated in this paper are nominally 19mm in diameter. Eight tubes have been used with trapezoidally shaped integral-fins having fin density from 748 to 1654 fpm and 10, 30 grooves. Plain tube having same diameter as finned tube is also tested for comparison. Experiments are carried out using R-11 as working fluid. The refrigerant condensates at a saturation state of $30^{\circ}C$ on the outside tube surface cooled by coolant. The amount of noncondensable gases present in the test loop is reduced to a negligible value by repeated purging. For a given heat input to the boiler and given cooling water flow rate, all test data are taken on steady state. The heat transfer loop is used for testing single long tubes and cooling water is pumped from a storage tank through filters and flowmeters to the horizontal test section where it is heated by steam condensing on the outside of the tube. The pressure drop across the test section is measured by means of pressure gauge and manometer. Each tube tested is cleaned with sodium dichromate pickling solution and well rinsed with water prior to installation in the test section. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, heat transfer of finned tube is enhanced up to 4 times as that of a plain tube at constant Reynolds number and up to 2 times at constant pumping power. 2. Friction factors are up to 1.6~2.1 times those of plain tube. 3. At a given Reynolds number, Nusselt number decrease with increasing pitch to diameter. 4. The constant pumping power ratio for low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio.

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Intercooler for Multi-stage Turbocharger Design and Analysis of the Hydrogen Reciprocating Engine for HALE UAV (고고도 장기체공 무인기용 수소 왕복 엔진의 다단터보차저용 인터쿨러 설계 및 해석)

  • Lee, Yang Ji;Rhee, Dong Ho;Kang, Young Seok;Lim, Byoeung Jun
    • The KSFM Journal of Fluid Machinery
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    • v.20 no.1
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    • pp.65-73
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    • 2017
  • Intercoolers for multi-stage turbocharger of the hydrogen reciprocating engine for HALE UAV are installed for reducing the charged air inlet temperature of the engine. The intercooler is air to air, cross flow, plate-fin type and the fin configuration is offset-strip fin which is referenced from the heat exchanger of the ERAST. Most of HALE UAV's cruising altitude is 60,000 ft and the density of air for this altitude is very low compared to sea level. Therefore the required heat transfer area for the HALE UAV is about three-times bigger than the sea level. Consequently, it is essential to design to meet the required efficiency of intercooler in the range of not excessively growing the weight of the heat exchanger. The quasi-one dimensional heat transfer design/analysis for satisfying the requirement of the engine are written in this paper. The numerical analyses for estimating the coolant flow rate of the engine bay and pressure loss in the header and core are also summarized.

Influence Analysis on the Number of Ruptured SG u-tubes During mSGTR in CANDU-6 Plants (중수로 증기발생기 다중 전열관 파단사고시 파단 전열관 수에 대한 영향 분석)

  • Seon Oh Yu;Kyung Won Lee
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.18 no.2
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    • pp.37-42
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    • 2022
  • An influence analysis on multiple steam generator tube rupture (mSGTR) followed by an unmitigated station blackout is performed to compare the plant responses according to the number of ruptured u-tubes under the assumption of a total of 10 ruptured u-tubes. In all calculation cases, the transient behaviour of major thermal-hydraulic parameters, such as the discharge flow rate through the ruptured u-tubes, reactor header pressure, and void fraction in the fuel channels is found to be overall similar to that of the base case having a single SG with 10 u-tubes ruptured. Additionally, as the conditions of low-flow coolant with high void fraction in the broken loop continued, causing the degradation of decay heat removal, the peak cladding temperature (PCT) would be expected to exceed the limit criteria for ensuring nuclear fuel integrity. However, despite the same total number of ruptured u-tubes, because of the different connection configuration between the SG and pressurizer, a difference is foud in time between the pressurizer low-level signal and reactor header low-pressure signal, affecting the time to trip the reactor and to reach the PCT limit. The present study is expected to provide the technical basis for the accident management strategy for mSGTR transient conditions of CANDU-6 plants.

Numerical and statistical analysis of Newtonian/non-Newtonian traits of MoS2-C2H6O2 nanofluids with variable fluid properties

  • Manoj C Kumar;Jasmine A Benazir
    • Advances in nano research
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    • v.16 no.4
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    • pp.341-352
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    • 2024
  • This study investigates the heat and mass transfer characteristics of a MoS2 nanoparticle suspension in ethylene glycol over a porous stretching sheet. MoS2 nanoparticles are known for their exceptional thermal and chemical stability which makes it convenient for enhancing the energy and mass transport properties of base fluids. Ethylene glycol, a common coolant in various industrial applications is utilized as the suspending medium due to its superior heat transfer properties. The effects of variable thermal conductivity, variable mass diffusivity, thermal radiation and thermophoresis which are crucial parameters in affecting the transport phenomena of nanofluids are taken into consideration. The governing partial differential equations representing the conservation of momentum, energy, and concentration are reduced to a set of nonlinear ordinary differential equations using appropriate similarity transformations. R software and MATLAB-bvp5c are used to compute the solutions. The impact of key parameters, including the nanoparticle volume fraction, magnetic field, Prandtl number, and thermophoresis parameter on the flow, heat and mass transfer rates is systematically examined. The study reveals that the presence of MoS2 nanoparticles curbs the friction between the fluid and the solid boundary. Moreover, the variable thermal conductivity controls the rate of heat transfer and variable mass diffusivity regulates the rate of mass transfer. The numerical and statistical results computed are mutually justified via tables. The results obtained from this investigation provide valuable insights into the design and optimization of systems involving nanofluid-based heat and mass transfer processes, such as solar collectors, chemical reactors, and heat exchangers. Furthermore, the findings contribute to a deeper understanding of stretching sheet systems, such as in manufacturing processes involving continuous casting or polymer film production. The incorporation of MoS2-C2H6O2 nanofluids can potentially optimize temperature distribution and fluid dynamics.

Study of On-chip Liquid Cooling in Relation to Micro-channel Design (마이크로 채널 디자인에 따른 온 칩 액체 냉각 연구)

  • Won, Yonghyun;Kim, Sungdong;Kim, Sarah Eunkyung
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.4
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    • pp.31-36
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    • 2015
  • The demand for multi-functionality, high density, high performance, and miniaturization of IC devices has caused the technology paradigm shift for electronic packaging. So, thermal management of new packaged chips becomes a bottleneck for the performance of next generation devices. Among various thermal solutions such as heat sink, heat spreader, TIM, thermoelectric cooler, etc. on-chip liquid cooling module was investigated in this study. Micro-channel was fabricated on Si wafer using a deep reactive ion etching, and 3 different micro-channel designs (straight MC, serpentine MC, zigzag MC) were formed to evalute the effectiveness of liquid cooling. At the heating temperature of $200^{\circ}C$ and coolant flow rate of 150ml/min, straight MC showed the high temperature differential of ${\sim}44^{\circ}C$ after liquid cooling. The shape of liquid flowing through micro-channel was observed by fluorescence microscope, and the temperarue differential of liquid cooling module was measuremd by IR microscope.