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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers B
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 33, Issue 12 - Dec 2009
Volume 33, Issue 11 - Nov 2009
Volume 33, Issue 10 - Oct 2009
Volume 33, Issue 9 - Sep 2009
Volume 33, Issue 8 - Aug 2009
Volume 33, Issue 7 - Jul 2009
Volume 33, Issue 6 - Jun 2009
Volume 33, Issue 5 - May 2009
Volume 33, Issue 4 - Apr 2009
Volume 33, Issue 3 - Mar 2009
Volume 33, Issue 2 - Feb 2009
Volume 33, Issue 1 - Jan 2009
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Status and Future of Experimental Study on Nuclear Thermal Hydraulics - A Review of Research and Development Status -
Park, Goon-Cherl ; Chun, Ji-Han ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 643~657
DOI : 10.3795/KSME-B.2009.33.9.643
This paper introduces the current nuclear experimental research activities in KAERI, the unique nuclear research institute in Korea, and the universities in Korea to solve and assess the issues which have been faced in the design of new reactors such as APR1400, SMART, GEN-IV reactors as well as fusion reactor. Also the experimental evaluations of safety for operating nuclear plants have been presented. The nuclear thermalhydraulic experiments performed in such organizations are classified the fundamental test, the separated effect test, and the integral effect test with ATLAS and SNUF. Introduction is deployed according to institutes. Finally, the future works and the direction of research voyage in the nuclear thermal-hydraulic field were suggested.
Effect of the Degree of Fuel-Air Mixing and Equivalence Ratio on the NOx Emission and Heat Release in a Dump Combustor
Cho, Bong-Kug ; Choi, Do-Wook ; Kim, Gyu-Bo ; Chang, Young-June ; Song, Ju-Hun ; Jeon, Chung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 658~665
DOI : 10.3795/KSME-B.2009.33.9.658
Lean premixed combustors are used for significant NOx reduction which one of issues in current gas turbine combustor. This study was investigated to estimate the effects of the unmixedness of fuel-air, equivalence ratio on the instability mechanism, NOx emission and combustion oscillation in a lean premixed combustor. The experiments were conducted in a dump combustor at atmospheric pressure conditions using methane as fuel. The swirler angle was
, the degrees of fuel-air mixing were 0, 50 and 100 and inlet temperature was 650K. The equivalence ratio was ranging from 0.5 to 0.8. This paper shows that NOx emission was increased when the degree of fuel-air mixing is increased in same equivalence ratio and when equivalence ratio is increased. And the range of the combustion instability was enlarged as a function of increasing of the degree of fuel-air mixing.
Investigation on the Turbulent Swirling Flow Field within the Combustion Chamber of a Gun-Type Gas Burner
Kim, Jang-Kweon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 666~673
DOI : 10.3795/KSME-B.2009.33.9.666
The turbulent swirling flow field characteristics of a gun-type gas burner with a combustion chamber were investigated under the cold flow condition. The velocities and turbulent quantities were measured by hot-wire anemometer system with an X-type probe. The turbulent swirling flow field in the edge of a jet seems to cause a recirculation flow from downstream to upstream due to the unbalance of static pressure between a main jet flow and a chamber wall. Moreover, because the recirculation flow seems to expand the main jet flow to the radial and to shorten it to the axial, the turbulent swirling flow field with a chamber increases a radial momentum but decreases an axial as compared with the case without a chamber from the range of about X/R=1.5. As a result, these phenomena can be seen through all mean velocities, turbulent kinetic energy and turbulent shear stresses. All physical quantities obtained around the slits, however, show the similar magnitude and profiles as the case without a chamber within the range of about X/R=1.0.
Direct Numerical Simulation of Turbulent Mixed Convection in Heated Vertical Annulus
Jun, Yong-Joon ; Bae, Joong-Hun ; Yoo, Jung-Yul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 674~681
DOI : 10.3795/KSME-B.2009.33.9.674
Turbulent mixed convection in heated vertical annulus is investigated using Direct Numerical Simulation (DNS) technique. The objective of this study is to find out the effect of buoyancy on turbulent mixed convection in heated vertical annulus. Downward and upward flows with bulk Reynolds number 8500, based on hydraulic diameter and mean velocity, have been simulated to investigate turbulent mixed convection by gradually increasing the effect of buoyancy. With increased heat flux, heat transfer coefficient first decreases and then increases in the upward flow due to the effect of buoyancy, but it gradually increases in downward flow. The mean velocity and temperature profiles can not be explained by the wall log laws due to the effect of buoyancy, too. All simulation results are in good quantitative agreement with existing numerical results and in good qualitative agreement with existing experimental results.
PIV Measurements on the Flame Initiation and Propagation under Gas Explosions by Electrostatic Discharge Energies in a Confined Chamber with an Obstacle
Park, Dal-Jae ; Lee, Seok-Hwan ; Sung, Jae-Yong ; Lee, Young-Soon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 682~687
DOI : 10.3795/KSME-B.2009.33.9.682
In order to investigate the effects of three different electrostatic discharge energies on gas explosions, a high-speed PIV system has been applied. The present study paid attention to the flame initiation by the gas explosions and its propagation at the existence of an obstacle within a chamber. Three different ignition energies such as 0.56 mJ, 52.87 mJ and 112.5 mJ were used. It is found that the ignition kernel is bent by the electrostatic discharge during the flame initiation. Tangential velocities of unburnt mixture ahead of initially propagating flame fronts are increased with increasing ignition energy, which makes the flame propagation faster before it reaches the obstacle. Although the flame speed was found to be less sensitive to the ignition energies, the flame developments were different. The effects of the energies on explosion pressures were also discussed.
Numerical Study of Land/Channel Flow-Field Optimization in Polymer Electrolyte Fuel Cells (PEFCs) (II) - The Effects of Land/Channel Flow-Field on Temperature and Liquid Saturation Distributions -
Ju, Hyun-Chul ; Nam, Jin-Moo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 688~698
DOI : 10.3795/KSME-B.2009.33.9.688
Using the multi-dimensional, multi-phase, nonisothermal Polymer Electrolyte Fuel Cell (PEFC) model presented in Part I, the effects of land/channel flow-field on temperature and liquid saturation distributions inside PEFCs are investigated in Part II. The focus is placed on exploring the coupled water transport and heat transfer phenomena within the nonisothermal and two-phase zone existing in the diffusion media (DM) of PEFCs. Numerical simulations are performed varying the land and channel widths and simulation results reveal that the water profile and temperature rise inside PEFCs are considerably altered by changing the land and channel widths, which indicates that oxygen supply and heat removal from the channel to the land regions and liquid water removal from the land toward the gas channels are key factors in determining the water and temperature distributions inside PEFCs. In addition, the adverse liquid saturation gradient along the thru-plane direction is predicted near the land regions by the numerical model, which is due to the vapor-phase diffusion driven by the temperature gradient in the nonisothermal two-phase DM where water evaporates at the hotter catalyst layer, diffuses as a vapor form and then condenses on the cooler land region. Therefore, the vapor phase diffusion exacerbates DM flooding near the land region, while it alleviates DM flooding near the gas channel.
Flame Structure of a Liftoff Non-Premixed Turbulent Hydrogen Jet with Coaxial Air
Oh, Jeong-Seog ; Yoon, Young-Bin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 699~708
DOI : 10.3795/KSME-B.2009.33.9.699
To understand hydrogen jet liftoff height, the stabilization mechanism of turbulent lifted jet flames under non-premixed conditions was studied. The objectives were to determine flame stability mechanisms, to analyze coexistence of two different flame structure, and to characterize the lifted jet at the flame stabilization point. Hydrogen flow velocity varied from 100 to 300 m/s. Coaxial air velocity was changed from 12 to 20 m/s. Simultaneous velocity field and reaction zone measurements used, PIV/OH PLIF techniques with Nd:YAG lasers and CCD/ICCD cameras. Liftoff height decreased with the increase of fuel velocity. The flame stabilized in a lower velocity region next to the faster fuel jet due to the mixing effects of the coaxial air flow. The flame stabilization was related to turbulent intensity and strain rate assuming that combustion occurs where local flow velocity and turbulent flame propagation velocity are balanced. At the flame base, two different flame structures were found that was the partial premixed flames and premixed flame.
Numerical Study on the Performance and the Heat Flux of a Coaxial Cylindrical Steam Reformer for Hydrogen Production
Park, Joon-Guen ; Lee, Shin-Ku ; Bae, Joong-Myeon ; Kim, Myoung-Jun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 709~717
DOI : 10.3795/KSME-B.2009.33.9.709
Heat transfer rate is a very important factor for the performance of a steam reformer because a steam reforming reaction is an endothermic reaction. Coaxial cylindrical reactor is the reactor design which can improve the heat transfer rate. Temperature, fuel conversion and heat flux in the coaxial cylindrical steam reformer are studied in this paper using numerical method under various operating conditions. Langmuir-Hinshelwood model and pseudo-homogeneous model are incorporated for the catalytic surface reaction. Dominant chemical reactions are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming (DSR) reaction. Although coaxial cylindrical steam reformer uses 33% less amount of catalyst than cylindrical steam reformer, its fuel conversion is increased 10 % more and its temperature is also high as about 30 degree. There is no heat transfer limitation near the inlet area at coaxial-type reactor. However, pressure drop of the coaxial cylindrical reactor is 10 times higher than that of cylindrical reactor. Operating parameters of coaxial cylindrical steam reformer are the wall temperature, the inlet temperature, and the Gas Hourly Space Velocity (GHSV). When the wall temperature is high, the temperature and the fuel conversion are increased due to the high heat transfer rate. The fuel conversion rate is increased with the high inlet temperature. However, temperature drop clearly occurs near the inlet area since an endothermic reaction is active due to the high inlet temperature. When GHSV is increased, the fuel conversion is decreased because of the heat transfer limitation and short residence time.
Thermoelectric Power Generation System with Loop Thermosyphon
Kim, Sun-Kook ; Rhi, Seok-Ho ; Won, Byung-Chul ; Kim, Dae-Hyun ; Lee, Chung-Gu ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 718~721
DOI : 10.3795/KSME-B.2009.33.9.718
A new progressive advanced approach (Loop thermosyphon Thermoelectric Power generation System) is suggested to optimize heat recovery ability from vehicle exhaust gas. As an initial look at device feasibility, the present new TE system adopted the loop thermosyphon as a cooling heat exchanger. The TE system with loop thermosyphon was investigated in terms of working fluids, instability of system, amount of working fluid, and so on. Basically, the present experimental works have been focused on finding the optimum working condition of the system to improve thermoelectric power output and to obtain stable power generation to operate hybrid vehicles. The present experimental results with the loop thermosyphon TE module shows possibilities as an improved TE system for future thermoelectric hybrid vehicles.
The Effect of the Intake Flow on the Spray Structure of a High Pressure 11-Hole Fuel Injector in a DISI Engine
Kim, Seong-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 33, issue 9, 2009, Pages 722~727
DOI : 10.3795/KSME-B.2009.33.9.722
The effect of the intake flow on the spray structure of a high pressure 11-hole fuel injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing and in-cylinder charge motion were investigated using the 2-dimensional Mie scattering technique. It was confirmed that in the homogeneous charge mode, the in-cylinder swirl charge motion played a major role in the fuel spray distribution during the induction stroke rather than the tumble flow. But, in the stratified charge mode, the effect of the in-cylinder charge was not so large that the injected spray pattern was nearly maintained and the increase of in-cylinder pressure by the upward moving piston reduced the fuel spray penetration.