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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
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 34, Issue 12 - Dec 2010
Volume 34, Issue 11 - Nov 2010
Volume 34, Issue 10 - Oct 2010
Volume 34, Issue 9 - Sep 2010
Volume 34, Issue 8 - Aug 2010
Volume 34, Issue 7 - Jul 2010
Volume 34, Issue 6 - Jun 2010
Volume 34, Issue 5 - May 2010
Volume 34, Issue 4 - Apr 2010
Volume 34, Issue 3 - Mar 2010
Volume 34, Issue 2 - Feb 2010
Volume 34, Issue 1 - Jan 2010
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Numerical Analysis of Effect of Inhomogeneous Pre-mixture on Pressure Rise Rate in HCCI Engine by Using Multizone Chemical Kinetics
Lim, Ock-Taeck ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 449~456
DOI : 10.3795/KSME-B.2010.34.5.449
The HCCI engine is a prospective internal combustion engine with which high diesel-like efficiencies and very low NOx and particulate emissions can be achieved. However, several technical issues must be resolved before HCCI engines can be used for different applications. One of the issues concerning the HCCI engine is that the operating range of this engine is limited by the rapid pressure rise caused by the release of excessive heat. This heat release is because of the self-accelerated combustion reaction occurring in the engine and the resulting engine knock in the high-load region. The purpose of this study is to evaluate the role of thermal stratification and fuel stratification in reducing the pressure rise rate in an HCCI engine. The concentrations of NOx and CO in the exhaust gas are also evaluated to confirm combustion completeness and NOx emission. The computation is carried out with the help of a multizone code, by using the information on the detailed chemical kinetics and the effect of thermal and fuel stratification on the onset of ignition and rate of combustion. The engine is fueled with dimethyl ether (DME), which allows heat release to occur in two stages, as opposed to methane, which allows for heat release in a single stage.
Development of Oil Skimmer with Submerged Orifice
Kou, Heung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 457~464
DOI : 10.3795/KSME-B.2010.34.5.457
Representative methods for removing spilled oil include mechanical skimming, chemical treatment, burning at the surface of the spilled oil, and microbiological degradation. Among these methods, mechanical skimmer is the most efficient. Mechanical skimming can be classified into the following categories: belt-type, disk-type, weir-type, drum-type. We designed models with a submerged orifice for use in our experiments, for an objective and systematic evaluation of the recovery efficiency of mechanical skimming. Basically, oil is lighter than seawater and hence tends to float on the surface of the latter if there is sufficient time for floating. The present skimmer is kind of wear-type with the submerged orifice for seawater to be squeezed through, minimizing water content in the tank. From the experimental results, we identify the parameters that influence the oil recovery rate and recovery efficiency. The recovery efficiency can be enhanced by increasing the thickness of the oil layer in the first oil accumulative tank.
Effect of Preventive Maintenance on Performance of Air Heater in a Power Plant
Jang, Jin-Hyung ; Hong, Eun-Kee ; Hwang, Kwang-Won ; Yun, Rin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 465~469
DOI : 10.3795/KSME-B.2010.34.5.465
Air heater used in power plant helps increase the thermal efficiency of the boiler by recovering the heat from the boiler flue gas and thus preventing the loss of useful heat. This study investigates the effect of preventive maintenance on the performance of the air heater in a power plant. Performance indexes for the air heater are calculated to observe the changes in the performance and operation status of the air heater before and after preventive maintenance. The major performance indexes considered are temperature efficiency of the flue gas side, air leakage rate, heat recovery rate, heat transmission rate, and heat capacity ratio. The performance of the air heater is evaluated before and after preventive maintenance; our results show that all the abovementioned performance indexes are improved after the maintenance.
Investigation of Bubble Behavior in Rectangular Microchannels for Different Aspect Ratios
Choi, Chi-Woong ; Yu, Dong-In ; Kim, Moo-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 471~479
DOI : 10.3795/KSME-B.2010.34.5.471
The adiabatic two-phase flow in single rectangular microchannels was studied for different aspect ratios. The working fluids were liquid water and nitrogen gas. The hydraulic diameters of the rectangular microchannels were 490, 322, and
, and the widths of the microchannels were around
. The two-phase flow pattern was visualized using a high-speed camera and a long-distance microscope. This study was focused on bubble flow regimes. From the visualized images, the bubble velocity, bubble length, number of bubbles, and void fraction were evaluated. Further, the pressure drop in a single bubble was evaluated by using a unit cell model. The bubble velocity is proportional to the superficial velocity. Further, the relationship between the void fraction and the volumetric quality is linear. The pressure drop in a single elongated bubble is strongly related to the aspect ratio. Finally, the new correlation about the pressure drop of a single elongated bubble in the rectangular microchannel was proposed.
Study on Laminar Mixed Convection of Developing Flow in Vertical Pipe
Ko, Bong-Jin ; Chung, Bum-Jin ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 481~489
DOI : 10.3795/KSME-B.2010.34.5.481
Experiments on laminar mixed convection in a vertical pipe were performed for the Re range 1,000-3,000, the
, the Pr range 2,000-7,000, and aspect ratio range 1-7. Using the analogy concept, heat transfer systems were simulated by mass transfer systems. A cupric acid.copper sulfate electroplating system was adopted as the mass transfer system, and the mass transfer rates were measured. The measured Nu values were far greater than those previously reported because of the large value of pr in this experiment. As the aspect ratio in this study was not sufficiently large for the flow to be fully developed, the test results were similar to those for mixed convection on a vertical plate rather than that inside a long vertical pipe. It was concluded that the behavior of laminar mixed convection of a developing flow in a vertical pipe at a low aspect ratio and low
is similar to that of laminar mixed convection in the vertical plate. As the aspect ratio and
increase, the laminar mixed convection phenomena becomes similar to that observed in a fully developed flow in the vertical pipe.
Humidification of Air Using Water Injector and Cyclonic Separator
Kim, Beom-Jun ; Kim, Sung-Il ; Byun, Su-Young ; Kim, Min-Soo ; Kim, Hyun-Yoo ; Kwon, Hyuck-Ryul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 491~498
DOI : 10.3795/KSME-B.2010.34.5.491
Humidification of PEM fuel cells is necessary for enhancing their performance and lifetime. In this study, a humidification system was designed and tested; the system includes an air-supply tube (inner diameter: 75 mm) through which a nozzle can be directly inserted and a cyclonic separator for the removal of water droplets. Three types of nozzles were employed to study the influence of injection pressure, air flow rate, and spray direction on the humidification performance. To evaluate the humidification performance, the concept of humidification efficiency was defined. In the absence of an external heat source, latent heat for evaporation will be supplied by the own enthalpies of water and air. Thus, the amount of water sprayed from the nozzle is the most critical factor affecting the humidification efficiency. Water droplets were efficiently removed by a cyclonic separator, but re-entrainment occurred at high air flow rates. The absolute humidity and humidification efficiency were
and 86.57%, respectively, under the following conditions: nozzle type PJ24; spray direction angle
; injection pressure 1200 kPa; air flow rate 6000 Nlpm.
Study on Estimation of PM Mass in DPF from Pressure Drop in 3L Diesel Engine
Kim, Hong-Suk ; Lee, Jin-Wook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 499~504
DOI : 10.3795/KSME-B.2010.34.5.499
It is important to determine the exact soot mass in a DPF system in order to control the timing of PM regeneration. The soot mass accumulated in a filter can be estimated from the pressure drop in the filter and the exhaust gas flow rates. In this study, the soot index is defined as the pressure drop in the DPF divided by the pressure drop in a DOC. An effective signal processing method for determining the soot index is proposed; the results yielded by this method indicate good correlation between the soot index and the amount of soot loaded into the filter for both steady-state and transient-state operating conditions in a 3L diesel engine for passenger vehicles.
Basic Study on Diffusion Branch of Tribrachial Flame with the Variation of Flammability Limits and Heat Loss Under Small Fuel Concentration Gradient
Cho, Sang-Moon ; Lee, Min-Jung ; Kim, Nam-Il ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 505~513
DOI : 10.3795/KSME-B.2010.34.5.505
The tribrachial flame has attracted interest as a basic structure of the flame edge. This flame structure helps understand stabilization of laminar flames and re-ignition of turbulent flames. A number of analytical and experimental studies have been carried out on the tribrachial flame. However, the effect of the variation of the flammability limits on the structure of the tribrachial flame has not been studied in detail. In this study, the effect of non-symmetric flammability limits on the flame structure was investigated by adopting a simple numerical scheme based on several laminar flame theories. A fixed velocity field was considered and boundary matching algorithm was used on the premixed branch. The variation of the diffusion branches under the non-symmetric flammability limits and heat loss was investigated. The formation and extinction of the diffusion branch behind the premixed branch were successfully described. This basic study can help understand the fundamental structure of the flame and can form the basis of subsequent detailed studies.
Experimental Study on the Air-Side Heat Transfer Characteristics of a Spirally-Coiled Circular Fin-Tube Heat Exchanger According to Geometric Parameters
Kang, Tae-Hyung ; Lee, Moo-Yeon ; Kim, Yong-Chan ; Yun, Sung-Jung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 515~522
DOI : 10.3795/KSME-B.2010.34.5.515
The objective of this study is to investigate the air-side heat transfer characteristics of a spirally-coiled circular fin-tube heat exchanger for various geometric parameters under non-frosting conditions. The heat transfer characteristics of the heat exchanger were analyzed with respect to heat exchanger geometries, and then, the characteristics were compared with those of rectangular-plate fin-tube heat exchangers with discrete fins. The heat transfer coefficient increased with a decrease in the number of tube rows and an increase in the fin pitch. The optimum length of the L-foot was 2.7 mm. In addition, the heat transfer rate increased with a decrease in the tube pitch and the tube thickness. The heat transfer coefficient of the spirally-coiled circular fin-tube heat exchanger was 24.3% higher than that of the rectangular-plate fin-tube heat exchanger.
Motion of Microbeads Propelled by Bacterial Chemotaxis
Kim, Dong-Wook ; Kim, Young-Won ; Yoo, Jung-Yul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 523~529
DOI : 10.3795/KSME-B.2010.34.5.523
Recently, several research groups have been investigating the motion of flagellated bacteria, with the aim of examining the feasibility of using bacterial chemotaxis as an efficient power source for microactuators. In this study, microparticle-tracking velocimetry (
-PTV) is used for investigating the motion of fluorescent microbeads propelled by bacterial chemotaxis. Flagellated bacteria, Serratia marcescens, are spontaneously attached to the surface of the fluorescent polystyrene (PS) microbeads in an aqueous culture. The microbeads thus treated are injected into the test medium, which contains the solidified chemoattractant L-aspartate. With time, the particles slowly move toward the zone in which the L-aspartate concentration is high. This study shows that chemotaxis of flagellated bacteria can be applied as an efficient power source for microactuators.
Optimum Design of Offset-Strip Fins
Kim, Min-Soo ; Lee, Kwan-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 531~537
DOI : 10.3795/KSME-B.2010.34.5.531
This paper optimized the design parameters of the offset strip fin in a heat exchanger. To decrease the pressure drop and increase heat transfer, the performance factors such as j/f,
, and JF, which could be used to estimate the pressure drop and heat transfer simultaneously, were employed as the criteria for optimization. In the present study, STDQAO, PQRSM, and MGA were used for solving the constrained nonlinear optimization problem. The JF factor and heat transfer performance of the optimized offset-strip fin were greater than those of the reference offset-strip fin by 36% and 280%, respectively.
Numerical Investigation of Effect of Surface Roughness in a Microchannel
Shin, Myung-Seob ; Byun, Sung-Jun ; Yoon, Joon-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 539~546
DOI : 10.3795/KSME-B.2010.34.5.539
In this paper, lattice Boltzmann method(LBM) results for a laminar flow in a microchannel with rough surface are presented. The surface roughness is modeled as an array of rectangular modules placed on the top and bottom surface of a parallel-plate channel. The effects of relative surface roughness, roughness distribution, and roughness size are presented in terms of the Poiseuille number. The roughness distribution characterized by the ratio of the roughness height to the spacing between the modules has a negligible effect on the flow and friction factors. Finally, a significant increase in the Poiseuille number is observed when the surface roughness is considered, and the effects of roughness on the microflow field mainly depend on the surface roughness.
Combustion Characteristics of Non-premixed VIStA Burner in Once-Through-Type Boiler
Ahn, Joon ; Kim, Hyouck-Ju ; Choi, Kyu-Sung ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 547~552
DOI : 10.3795/KSME-B.2010.34.5.547
A modified VIStA (vortex inertial staged air) burner was developed and used in a once-through-type boiler. For safety, the combustion in this burner is of the non-premixed type. An air damper is installed to control the distribution of air to each combustion chamber. The effects of the air-fuel ratio and air distribution on NOx formation were investigated. The newly modified VIStA burner gives NOx reduction effect by maximum 20% in the combustion chamber of a boiler, while it yields more uniform flame than the conventional burner.
CFD Analysis for Simulating Very-High-Temperature Reactor by Designing Experimental Loop
Yoon, Churl ; Hong, Sung-Deok ; Noh, Jae-Man ; Kim, Yong-Wan ; Chang, Jong-Hwa ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 553~561
DOI : 10.3795/KSME-B.2010.34.5.553
A medium-scale helium loop that can simulate a VHTR (very-high-temperature reactor) is now under construction at the Korea Atomic Energy Research Institute. The heaters of the test helium loop electrically heat helium fluid up to
at pressures of 1 to 9 MPa. To optimize the design specifications of the experimental helium loop, the conjugate heat transfer in the high-temperature helium heater was analyzed by performing a CFD simulation. The analysis results indicate that the maximum temperature does not exceed the allowable limit. It is confirmed that the thermal characteristics of the loop with the given geometry satisfy the design requirements.
Study on Turbopump-Gas Generator Open-Loop Coupled Test
Kim, Seung-Han ; Nam, Chang-Ho ; Kim, Cheul-Woong ; Moon, Yoon-Wan ; Seol, Woo-Seok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 34, issue 5, 2010, Pages 563~568
DOI : 10.3795/KSME-B.2010.34.5.563
Turbopump-gas generator open-loop coupled tests are performed during the development of a 30tonf-LOx/Kerosene rocket engine. In the turbopump-gas generator open-loop tests, the propellants to gas generator are supplied from the outlets of turbopump, while the gas exhausted from the gas generator is vented out to the atmosphere, instead of being used to turbine driving. This paper presents the objectives, procedure, and results of the open-loop coupled test, in addition to a schematic representation of the test apparatus and the operating conditions for the test facility system and control system. The results of turbopump-gas generator open-loop coupled test confirm chill-down procedure, startup characteristics, nominal operability and smooth shutdown of the open-loop coupled Test Plant in test conditions simulating engine system operation environment.