• Title/Summary/Keyword: Heat flux test

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A Study on Transport and Heat Utilization of Ice Slurries (아이스 슬러리의 수송 및 냉열이용에 관한 연구)

  • 길복임;이윤표;정동주;조봉현;최은수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.11
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    • pp.1065-1071
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    • 2001
  • To investigate hydraulic and thermal characteristics of ice slurries in a circular tube, ice slurries were tested in a flow loop with a constant heat flux test section, for ranges of flow velocity, ice fraction and heat flux. Heat transfer coefficients and friction factors of ice slurries were calculated by measuring the outer wall temperatures of the test section and the pressure drops over the test section. Heat transfer coefficients of ice slurries were 9% higher than the heat transfer coefficients expected by Petukhov. Friction factors were about 4% lower than the friction factors expected by Petukhov. The effective thermal capacity of ice slurry with 12.8% ice fraction, was found to be about 3 times higher than the thermal capacity of water.

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Convective Heat Transfer of Using an Ice Slurry in n circular pipe (아이스 슬러리의 원형관내 대류열전달에 관한 연구)

  • Jung, Dong-Ju;Choi, Eun-Soo
    • Proceedings of the KSME Conference
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    • 2000.11b
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    • pp.130-135
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    • 2000
  • To enhance heat transfer characteristics of water, fine ice was added to it. The convective heat transfer characteristics of the ice slurry were investigated in a flow loop with a constant heat flux test section. The Nusselt number and Fanning friction coefficient of water flow were found to be similar to the expected curve by Petukhov. The Nusselt number of the ice sin flow was higher than the Nusselt number of water. Effective thermal capacity of the 10.84% ice slurry was found to have 2.39 times of the thermal capacity of water.

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Characteristics of tungsten coated graphite using vacuum plasma spraying method

  • Lim, Hyeonmi;Kang, Boram;Kim, Hoseok;Hong, Bong Guen
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.200.1-200.1
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    • 2016
  • Tungsten coatings on the graphite (CX-2320) were successfully deposited using the vacuum plasma spraying (VPS) method. An optimum coating procedure was developed and coating thicknesses of $409{\mu}m$ (without an interlayer) and $378{\mu}m$ (with an interlayer) were obtained with no cracks and no signs of delamination. The mechanical characteristics and microstructure of the tungsten coating layers were investigated using a Vickers hardness tester, FE-SEM, EDS, and XRD. The effect of a titanium interlayer on the properties of the tungsten coating was investigated. It was shown that the titanium interlayer prevented the diffusion of carbon to the tungsten layer, thereby suppressing the formation of tungsten carbide. Vickers hardness data yielded values that were 62.5 ~ 80.46% of those for bulk tungsten, indicating that tungsten coatings on graphite can be utilized as a plasma-facing material. High heat flux tests were performed by using thermal plasma with a maximum flux of $10MW/^2$. Vickers hardness after the heat flux test is performed to see a change in the mechanical properties. The formationof a tungsten carbide and the effect of the titanium interlayer for the diffusion barrier are investigated by using energy dispersion spectroscopy (EDS).

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Enhancement of Convective Heat Transfer by Using a Micro-Encapsulated Phase-Change-Material Slurry (피복된 미립 상변화물질 슬러리를 이용한 대류 열전달의 향상에 관한 연구)

  • Jung, Dong-Ju;Choi, Eun-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.9
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    • pp.1277-1284
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    • 2000
  • To enhance heat transfer characteristics of water, micro-encapsulated octadecane of about $10{\mu}m$ diameter was added to water. Viscosity of the slurry was measured by using a capillary tube viscometer. The measured viscosity decreased as the temperature of the slurry increased, and it increased as the fraction of the capsules in the slurry increased. Thermal characteristics of the octadecane were studied by using a differential scanning calorimeter. The melting temperature and the melting energy of the octadecane were found to be $28.6^{\circ}$ and 34.4kcal/kg, respectively. The convective heat transfer characteristics of the slurry were investigated in a flow loop with a constant heat flux test section. Friction factor of the slurry flow was found to be similar to the expected curve by Petukhov. The Nusselt number of the slurry flow was highest when the octadecane melted. Effective thermal capacity of the 14.2% slurry was found to have 1.67 times of the thermal capacity of water.

Pool Boiling Heat Transfer Coefficient of HFC32/HFC152a on a Plain Surface (평판 표면에서 HFC32/HFC152a 혼합냉매의 풀 비등 열전달계수)

  • Kang, Dong-Gyu;Lee, Yohan;Jung, Dongsoo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.9
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    • pp.484-492
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    • 2013
  • Nucleate pool boiling heat transfer coefficients (HTCs) are measured with HFC32/HFC152a mixture at several compositions. All data are taken at the liquid pool temperature of $7^{\circ}C$, on a horizontal plain square surface of $9.53{\times}9.53$ mm, with heat fluxes of 10 $kW/m^2$ to 100 $kW/m^2$ with an interval of 10 $kW/m^2$, in the increasing order of heat flux. Test results show that the HTCs of these mixtures are up to 45% lower than those of the ideal HTCs calculated by a linear mixing rule with pure fluids' HTCs, due to the mass transfer resistance associated with non-azeotropic refrigerant mixtures. Pool boiling data show the deduction in HTCs with an increase in GTD of the mixture. The present mixture data agree well with five well known correlations, within 20% deviation.

A Study of Application on the Pulsating Heat Pipe for Heat Transfer Enhancement of Metal Hydride Alloy (수소 저장합금층의 열전달 촉진을 위한 진동형 히트 파이프 적용에 관한 연구)

  • Lee, Min-Jae;Im, Yong-Bin;Bae, Sang-Chul;Kim, Jong-Soo
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.346-351
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    • 2006
  • When metallic alloys are reacted to hydrogen, heat transfer of storage tank effects hydrogen storage rate and capacity. If pulsating heat pipe are used to improve heat transfer efficiency, production of hydrogen storage tank can be more simple and economical. Experiment of heat pipe was conducted by varying working fluids and heat flux. According to supply heat flux, test indicate that R-22 and R-l42b were found lower temperature difference between evaporator and condenser than R-134a and Ethanol. Thermal resistances of R-22 and R-142b were also lower than others. Using R-142b as a working fluid, heat pipe type hydrogen storage tank is tested in absorption and desorption processes.

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Contribution of thermal-hydraulic validation tests to the standard design approval of SMART

  • Park, Hyun-Sik;Kwon, Tae-Soon;Moon, Sang-Ki;Cho, Seok;Euh, Dong-Jin;Yi, Sung-Jae
    • Nuclear Engineering and Technology
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    • v.49 no.7
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    • pp.1537-1546
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    • 2017
  • Many thermal-hydraulic tests have been conducted at the Korea Atomic Energy Research Institute for verification of the SMART (System-integrated Modular Advanced ReacTor) design, the standard design approval of which was issued by the Korean regulatory body. In this paper, the contributions of these tests to the standard design approval of SMART are discussed. First, an integral effect test facility named VISTA-ITL (Experimental Verification by Integral Simulation of Transients and Accidents-Integral Test Loop) has been utilized to assess the TASS/SMR-S (Transient and Set-point Simulation/Small and Medium) safety analysis code and confirm its conservatism, to support standard design approval, and to construct a database for the SMART design optimization. In addition, many separate effect tests have been performed. The reactor internal flow test has been conducted using the SCOP (SMART COre flow distribution and Pressure drop test) facility to evaluate the reactor internal flow and pressure distributions. An ECC (Emergency Core Coolant) performance test has been carried out using the SWAT (SMART ECC Water Asymmetric Two-phase choking test) facility to evaluate the safety injection performance and to validate the thermal-hydraulic model used in the safety analysis code. The Freon CHF (Critical Heat Flux) test has been performed using the FTHEL (Freon Thermal Hydraulic Experimental Loop) facility to construct a database from the $5{\times}5$ rod bundle Freon CHF tests and to evaluate the DNBR (Departure from Nucleate Boiling Ratio) model in the safety analysis and core design codes. These test results were used for standard design approval of SMART to verify its design bases, design tools, and analysis methodology.

High Heat Flux Test of Cu/SS Mock-up for ITER First Wall (ITER 일차벽의 Cu/SS Mock-up에 대한 고열부하 시험)

  • Lee, D.W.;Bae, Y.D.;Hong, B.G.;Lee, J.H.;Park, J.Y.;Jeong, Y.H.
    • Journal of the Korean Vacuum Society
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    • v.15 no.3
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    • pp.325-330
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    • 2006
  • In order to verify the integrity of the first wall (FW) of the International Thermonuclear Experimental Reactor (ITER), the fabricated Cu/SS mock-up is tested in the JAEA Electron Beam Irradiation Test Stand (JEBIS). To fabricate the Cu/SS mock-up, CuCrZr and 316L authentic stainless steel (SS316L) are used for Cu alloy and steel, respectively The hot isostatic pressing (HIP) is used as a manufacturing method with a $1050^{\circ}C$ and 150 MPa. The high heat flux (HHF) test is performed using an electron beam with a heat flux of $5MW/m^2$ and a cycle of 15-sec on time and 30-sec off time. The temperature measurement in the HHF test shows good agreement with the results obtained from ANSYS code analysis, which is used for determining the HHF test conditions.