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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 36, Issue 12 - Dec 2012
Volume 36, Issue 11 - Nov 2012
Volume 36, Issue 10 - Oct 2012
Volume 36, Issue 9 - Sep 2012
Volume 36, Issue 8 - Aug 2012
Volume 36, Issue 7 - Jul 2012
Volume 36, Issue 6 - Jun 2012
Volume 36, Issue 5 - May 2012
Volume 36, Issue 4 - Apr 2012
Volume 36, Issue 3 - Mar 2012
Volume 36, Issue 2 - Feb 2012
Volume 36, Issue 1 - Jan 2012
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Experimental Investigation of Variations in Inclination Angle of Natural Convective Heat Sink with Plate Fins
Do, Kyu-Hyung ; Kim, Tae-Hoon ; Han, Yong-Shik ; Choi, Byung-Il ; Kim, Myung-Bae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 571~578
DOI : 10.3795/KSME-B.2012.36.6.571
In this paper, an experimental investigation is performed to estimate the thermal performance of a natural convective heat sink with plate fins subject to the uniform wall temperature condition. Extensive experiments are performed with various input powers, fin spacings, and heights of the natural convective heat sinks with plate fins. In particular, the effect of the inclination angle on the thermal performance of the heat sink is studied. In order to validate the experimental data, the experimental results are compared with results from previous studies. Based on the experimental results, the appropriate ranges of the previous correlations between the input power, the fin spacing, the fin height, and the inclination angle for the natural convective heat sink with plate fins are evaluated.
Development of System for Measuring Evaporation Rate through Porous Medium in Fuel Cells
Kim, Jong-Rok ; Kim, Moo-Hwan ; Son, Sang-Young ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 579~582
DOI : 10.3795/KSME-B.2012.36.6.579
Removing residual water in a fuel cell is a critical operational process for managing its performance and controlling its lifetime. Understanding the mechanism of water transport in fuel cells is essential for the design of the water removal process. In this study, an experimental method for measuring the water evaporation rate through a gas diffusion layer, which is a porous medium, under steady-state conditions was developed. Experimental bench tests were conducted to apply the developed method. Then, the effects of various parameters of the drying gas and the gas diffusion layer were experimentally measured. The water evaporation rate increased as the humidity of the drying gas decreased and the flow rate of the drying gas increased. In addition, a thinner gas diffusion layer yielded a higher water evaporation rate.
Performance Characteristics of Plate Heat Exchangers with Various Geometric Design Parameters
Son, Jae-Wook ; Lee, Eung-Chan ; Kang, Hoon ; Kim, Yong-Chan ; Kim, Jung-Kyu ; Cho, Sung-Youl ; Park, Jae-Hong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 583~591
DOI : 10.3795/KSME-B.2012.36.6.583
Plate heat exchangers have been widely used in many industrial applications because of their compactness and high efficiency. Even though plate heat exchangers have been investigated extensively, studies on the effects of geometric parameters other than the chevron angle are very limited in the open literature. In this study, the effects of the chevron angle, corrugation length, corrugation depth, and the number of plates on the heat transfer and pressure drop characteristics of plate heat exchangers were investigated experimentally. Based on the experimental results, empirical correlations were proposed. More than 95% of the predictions made based on the correlations had relative deviations of less than
when compared with the measured data.
Exhaust-Gas Heat-Recovery System of Marine Diesel Engine (II) - Exergy Analysis for Working Fluids of R245fa and Water -
Choi, Byung-Chul ; Kim, Young-Min ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 593~600
DOI : 10.3795/KSME-B.2012.36.6.593
The exergy characteristics for R245fa and water working fluids have been analyzed for an electric generation system utilizing the Rankine cycle to recover heat from the wasted exhaust gas from a diesel engine used for the propulsion of a large ship. The theoretical calculation results showed that the efficiencies of exergy and system exergy improved as the turbine inlet pressure increased for R245fa at a fixed mass flow rate. Furthermore, the exergy destruction rates of the condenser and evaporator were relatively larger than those in other components. The exergy efficiency of the system increased with increasing mass flow rate. For a water working fluid, although the exergy destruction rate of the evaporator was similar to that for R245fa, the exergy loss rate varied significantly in response to variations in the pressure and mass flow rates at the turbine inlet.
Performance of Various Drug-Eluting Stent Geometries Measured Using Computational Analysis
Seo, Tae-Won ; Barakat, Abdul I. ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 601~607
DOI : 10.3795/KSME-B.2012.36.6.601
In this study, we performed computational fluid dynamic simulations to explore how the detailed design of drug-eluting stents affects both the flow field in the vicinity of the stent as well as the concentration of the eluted drug at the endothelial cell surface. Simulations were performed on three idealized stent geometries we developed and on geometries approximating three commercial stents,: Medtronic's Aurora stent, Cordis's BX Velocity stent, and Boston Scientific's Wallstent. An important contribution of the present study is the introduction of the stent effectiveness index (EI), which provides a quantitative assessment of stent performance and an objective basis for comparing the performance of different stents. Among the three commercial stents studied, our simulations have revealed that the BX Velocity stent is associated with the lowest in-stent EI values for the range of flow Reynolds numbers studied (
). In addition to commercial stent designs, we investigated the EI in three idealized stents and determined that a spiral stent provides excellent performance (low EI) under all flow conditions investigated.
Numerical Study of Impact of Microdroplet Containing Nanoparticles
Roh, Sang-Eun ; Son, Gi-Hun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 609~617
DOI : 10.3795/KSME-B.2012.36.6.609
The impact, spreading and recoil processes of a nanoparticle-laden droplet impacting on a horizontal solid surface are numerically investigated by solving the conservation equations for mass, momentum, energy and mass fraction. The liquid-air interface is tracked using a level-set method that is modified to include the effect of contact angle hysteresis at the wall. The species transport equation including a thermal diffusion term is additionaly solved to determine the nanoparticle distribution in the droplet. The effect of nanoparticle concentration and contact angle are also studied.
Characteristics of Electroosmotic Pump with Cylindrical Porous Glass Frits
Kwon, Kil-Sung ; Kim, Dae-Joong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 619~624
DOI : 10.3795/KSME-B.2012.36.6.619
In this study, we demonstrated the operation of an electroosmotic pump with cylindrical porous glass frits and evaluated its long-term operation. The performance of this electroosmotic pump was characterized in terms of maximum flow rate, current, and pressure using deionized water and 1 mM borate buffer. The maximum flow rate, current, and pressure linearly increase with voltage. The maximum flow rate is normalized by the pumping area and voltage for comparison of the performance between the electroosmotic pumps with cylindrical and planar frits. The normalized maximum flow rate of the cylindrical-type pump is higher than that of the planar-type pump because of their different geometries. The cylindrical-type electroosmotic pump has five times better performance than the planartype electroosmotic pump for a given pump package volume. It can operate stably for over 3 hours.
Study on Flooding Phenomena at Various Stoichiometries in Transparent PEM Unit Fuel Cell
Nam, Ki-Hoon ; Byun, Jae-Ki ; Choi, Young-Don ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 625~632
DOI : 10.3795/KSME-B.2012.36.6.625
The objective of this paper is to demonstrate the cathode channel flooding effects at different stoichiometries in proton exchange membrane (PEM) fuel cells by using visualization techniques. The phenomena of liquid water formation and removal caused by current variations were also examined experimentally. Tests were conducted at cathode stoichiometries of 1.5 and 2.0, and the anode stoichiometry was fixed at 1.5. It is found that at an air-side stoichiometry of 2.0, liquid water begins to form and the flooding occurs faster than at an air-side stoichiometry of 1.5. Also, when the air-side stoichiometry of 1.5 is maintained, the dry-out phenomena is observed in the dry-out area 7.8 A following the field of flooding. Thus, a stoichiometry of 1.5 produced better performance in terms of membrane electrode assembly (MEA) durability and hydrogen ion conductivity than did a stoichiometry of 2.0, in which dry-out occurs beyond 8A.
Assessment of Maximum Spreading Models for a Newtonian Droplet Impacting on a Solid Surface
An, Sang-Mo ; Lee, Sang-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 633~638
DOI : 10.3795/KSME-B.2012.36.6.633
The maximum spreading is the maximum extent to which a drop can spread after impacting on a surface. It is one of the crucial factors determining the spraying performance in many applications. In this study, the existing maximum spreading models for a Newtonian liquid droplet impacting on a dry solid surface were reviewed and compared with the experimental results over the ranges of
. The surface wettability was found to have only a minor influence on the maximum spreading, compared to the liquid viscosity and impact velocity. Among the models tested, the Roisman (2009) model showed the best agreement with the experimental results, matching 80% of the measured data within
Characteristics of Autoignited Laminar Lifted Flames in Heated Coflow Jets of Carbon Monoxide/Hydrogen Mixtures
Choi, Byung-Chul ; Chung, Suk-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 639~646
DOI : 10.3795/KSME-B.2012.36.6.639
The characteristics of autoignited lifted flames in laminar jets of carbon monoxide/hydrogen fuels have been investigated experimentally in heated coflow air. In result, as the jet velocity increased, the blowoff was directly occurred from the nozzle-attached flame without experiencing a stabilized lifted flame, in the non-autoignited regime. In the autoignited regime, the autoignited lifted flame of carbon monoxide diluted by nitrogen was affected by the water vapor content in the compressed air oxidizer, as evidenced by the variation of the ignition delay time estimated by numerical calculation. In particular, in the autoignition regime at low temperatures with added hydrogen, the liftoff height of the autoignited lifted flames decreased and then increased as the jet velocity increased. Based on the mechanism in which the autoignited laminar lifted flame is stabilized by ignition delay time, the liftoff height can be influenced not only by the heat loss, but also by the preferential diffusion between momentum and mass diffusion in fuel jets during the autoignition process.
Short Reaction Mechanism for Premixed CH
-Air Flames at High Pressure
Lee, Su-Gak ; Lee, Ki-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 647~653
DOI : 10.3795/KSME-B.2012.36.6.647
A short reaction mechanism for premixed
-air flames at high pressure was developed using a reduction method based on the combined application of the simulation error minimization connectivity method and the iterative species-removal sensitivity method. It consisted of 43 species and 554 elementary reactions under the condition that it produces less than 5% of the maximum error. The flame structures obtained using a detailed reaction mechanism and the short reaction mechanism were compared for
-air flames with various initial temperatures and equivalence ratios at high pressure, and the results were in good agreement. Therefore, the short reaction mechanism developed could reproduce the flame speeds, temperatures, and concentrations of major and minor species at high pressure.
Detection of Abnormal Leakage and Its Location by Filtering of Sonic Signals at Petrochemical Plant
Yoon, Young-Sam ; Kim, Cheol ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 655~662
DOI : 10.3795/KSME-B.2012.36.6.655
Gas leakage in an oil refinery causes damage to the environment and unsafe conditions. Therefore, it is necessary to develop a technique that is able to detect the location of the leakage and to filter abnormal gas-leakage signals from normal background noise. In this study, the adaptation filter of the finite impulse response (FIR) least mean squares (LMS) algorithm and a cross-correlation function were used to develop a leakage-predicting program based on LABVIEW. Nitrogen gas at a high pressure of 120 kg/
and the assembled equipment were used to perform experiments in a reverberant chamber. Analysis of the data from the experiments performed with various hole sizes, pressures, distances, and frequencies indicated that the background noise occurred primarily at less than 1 kHz and that the leakage signal appeared in a high-frequency region of around 16 kHz. Measurement of the noise sources in an actual oil refinery revealed that the noise frequencies of pumps and compressors, which are two typical background noise sources in a petrochemical plant, were 2 kHz and 4.5 kHz, respectively. The fact that these two signals were separated clearly made it possible to distinguish leakage signals from background noises and, in addition, to detect the location of the leakage.
Application and Verification of Cold Air Velocity Technique for Solving Tube Ash Erosion Problem in PC Boilers
Yoo, Ki-Soo ; Jeong, Kwon-Seok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 663~668
DOI : 10.3795/KSME-B.2012.36.6.663
Fly ash erosion is a leading cause of boiler tube failure in PC boilers. Therefore, shields or baffle plates are installed in specific areas to mitigate fly ash erosion and prevent boiler tube failure. However, the tube failure problems caused by fly ash erosion cannot be eliminated with this solution alone, because each PC boiler has a different flue-gas flow pattern and erosion can become severe in unexpected zones. This problem is caused by an asymmetric internal flow velocity and local growth of the flue gas velocity. For these reasons, clearly defining the flow pattern in PC boilers is important for solving the problem of tube failure caused by fly ash erosion. For this purpose, the cold air velocity technique (CAVT) can be applied to the fly ash erosion problem. In this study, CAVT was carried out on the Hadong #2 PC boiler and the feasibility of application of CAVT to conventional PC boilers was validated.
Optimization of the Community Energy Supply System for D-Cube City, Multi Purpose Building
Lee, Tae-Won ; Kim, Yong-Ki ; Lee, Kun-Woo ; Lee, Ki-Bong ; Cho, Dong-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 36, issue 6, 2012, Pages 669~674
DOI : 10.3795/KSME-B.2012.36.6.669
D-Cube City is a recently completed multi purpose building consisting of four types of facilities; offices, a department store, a hotel, and congregation spaces. A community energy supply system(CES) has been installed to supply this building with electricity, steam, heat, and cold water. The BEMS, building energy management system, is currently being designed to reduce building energy consumption through the efficient operation of the various pieces of building service equipment. In this study the optimal methods for operating the CES of D-Cube City were considered. This system includes three combined heat and power systems, seven steam boilers, two hot water boilers, two absorption chillers, and four turbo chillers, and various other pieces of equipment. In result, the optimal methods of operating the CES for various energy demand levels were obtained along with the seasonal effects on the economic efficiency of the operation. The effect of the amount of energy demanded by the various facility areas on the total energy consumption was also analyzed.