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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
Editor in Chief :
Volume & Issues
Volume 35, Issue 12 - Dec 2011
Volume 35, Issue 11 - Nov 2011
Volume 35, Issue 10 - Oct 2011
Volume 35, Issue 9 - Sep 2011
Volume 35, Issue 8 - Aug 2011
Volume 35, Issue 7 - Jul 2011
Volume 35, Issue 6 - Jun 2011
Volume 35, Issue 5 - May 2011
Volume 35, Issue 4 - Apr 2011
Volume 35, Issue 3 - Mar 2011
Volume 35, Issue 2 - Feb 2011
Volume 35, Issue 1 - Jan 2011
Selecting the target year
Study on Performance and Emission Characteristics of CNG/Diesel Dual-Fuel Engine
Lim, Ock-Taeck ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 869~874
DOI : 10.3795/KSME-B.2011.35.9.869
In a CNG/diesel dual-fuel engine, CNG is used as the main fuel and a small amount of diesel is injected into the cylinder to provide ignition priming. In this study, a remodeling of the existing diesel engine into a CNG/diesel dual-fuel engine is proposed. In this engine, diesel is injected at a high pressure by common rail direct injection (CRDI) and CNG is injected at the intake port for premixing. The CNG/diesel dual-fuel engine had an equally satisfactory coordinate torque and power as the conventional diesel engine. Moreover, the CNG alternation rate is over 89% throughout the operating range of the CNG/diesel dual-fuel engine. PM emission by the dual-fuel engine is 94% lower than that by the diesel engine; however, NOx emission by the dual-fuel engine is higher than that by the diesel engine.
Modification of Balancing Piston for Trimming of Impeller Diameter for Maintaining Axial-Thrust Balance in Low-Specific-Speed Multistage Centrifugal Pumps
Yoo, Il-Su ; Park, Moo-Ryong ; Yoon, Eui-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 875~882
DOI : 10.3795/KSME-B.2011.35.9.875
In the present study, the imbalance in the axial-thrust and variation in the volumetric efficiency that occurred during the trimming of impeller diameter were investigated. The present study was focused on low-specific-speed multistage centrifugal pumps with a balancing piston as the balancing mechanism. The effects of impeller trimming on the axial-thrust balance in multistage pumps with horizontal and vertical axes were compared. The results showed that impeller trimming resulted in an additional axial-thrust acting in direction of pump inlet. The axial-thrust imbalance due to impeller trimming was more severe in the vertical-axis pumps than in the horizontal-axis pumps. The rate of increase in the diameter of the balancing piston, which was proportional to the rate of impeller trimming, was evaluated to maintain the axial-thrust balance. Furthermore, a simultaneous increase in the piston length and piston diameter was more effective for reducing the axial-thrust imbalance along with the volumetric efficiency drop.
Numerical Analysis of Flow Fields for Optimum Design of Vehicle Vacuum Pump with Multivanes
Lim, Tae-Eun ; Lee, Kye-Bock ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 883~890
DOI : 10.3795/KSME-B.2011.35.9.883
A numerical study was conducted to determine the optimal design for a vehicle vacuum pump. The degree of vacuum was examined for different design factors such as the angle of vanes, number of vanes, angle and position of the pump inlet-outlet pipe, and angular rotational speed of vanes. The results show that there is a little difference in the degree of vacuum when the angle of vanes are changed, but an angular change in the outlet pipe reduces the pump loss. As the rotational speed is increased, the mass flow rate increases, but a high rotational speed does not result in the maximum degree of vacuum. In addition, when the number of vanes is increased, the scattering range of mass flow rate decreases and pressure drop is abated.
Study on Heat Transfer Characteristics for Single-phase Flow in Rectangular Microchannels
Mun, Ji-Hyun ; Kim, Seon-Chang ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 891~896
DOI : 10.3795/KSME-B.2011.35.9.891
In this study, experiments were carried out to investigate the convective heat transfer characteristics of rectangular microchannels. The sample used in the experiments contained 20 rectangular microchannels in parallel. The channels had a hydraulic diameter of 700
. Distilled water was used as the working fluid. In the experiments, the Reynolds number ranged from 400 to 800, heat flux ranged from 35 to 85 kW/
, and the inlet fluid temperature was
. As a result, the convective heat transfer coefficient increased upon increasing the Reynolds number and ranged from 4.6 to 6.4 kW/
in the thermally fully developed region. Moreover, the higher the Reynolds number, the longer the thermal entry length in the rectangular microchannels. However, it was observed that a variable heat flux did not affect the thermal entry length. In conclusion, a correlation was proposed to indicate the heat transfer characteristics in a thermally fully developed region.
Investigation of Equivalent Circuit for PEMFC Assessment
Myong, Kwang-Jae ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 897~902
DOI : 10.3795/KSME-B.2011.35.9.897
Chemical reactions occurring in a PEMFC are dominated by the physical conditions and interface properties, and the reactions are expressed in terms of impedance. The performance of a PEMFC can be simply diagnosed by examining the impedance because impedance characteristics can be expressed by an equivalent electrical circuit. In this study, the characteristics of a PEMFC are assessed using the AC impedance and various equivalent circuits such as a simple equivalent circuit, equivalent circuit with a CPE, equivalent circuit with two RCs, and equivalent circuit with two CPEs. It was found in this study that the characteristics of a PEMFC could be assessed using impedance and an equivalent circuit, and the accuracy was highest for an equivalent circuit with two CPEs.
Effects of Compound Angle, Diffuser Angle, and Hole Pitch on Film-cooling Effectiveness
Kim, Sun-Min ; Lee, Ki-Don ; Kim, Kwang-Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 903~913
DOI : 10.3795/KSME-B.2011.35.9.903
A numerical study is carried out to analyze the steady three-dimensional turbulent flow through cylindrical and fan-shaped holes and the film cooling of these holes at low and high blowing ratios. Compressible Reynoldsaveraged Navier-Stokes equations and the energy equation are solved using a finite-volume-based solver, and a shearstress transport model is used as the turbulence closure. The effects of the compound angle, pitch to diameter ratio, and lateral expansion angle of the hole on the film-cooling effectiveness are evaluated by the film-cooling effectiveness. It is observed that the compound angle of the hole enhances the film performance for the cylindrical hole, and a small hole pitch induces interactions between the coolants from the adjacent holes, thus reducing the film-cooling performance.
A Numerical Study on the Thermal Stimulation of Continuous Moxibustion
Yang, So-Ra ; Kang, Ho-Young ; Jeon, Byoung-Jin ; Choi, Hyoung-Gwon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 915~922
DOI : 10.3795/KSME-B.2011.35.9.915
In this paper, the unsteady incompressible Navier-Stokes equation coupled with energy equation was solved in order to investigate the thermal stimulation of continuous moxibustion using a commercial code (ANSYS-Fluent). In the simulations, various periods were selected for the continuous moxibustion, which was done by burning multiple disks successively. It has been found that the depth of the effective stimulation zone increases only when the replacing temperature is equal or larger than body temperature whereas the increase rate of the effective stimulation depth decreases as the number of disc increases. Further, it has been shown that the optimal period, for which the duration time of the effective stimulation zone is maximum, exists.
Numerical Study on Heat Transfer Characteristics of Turbulent Flow in Transition Duct
Yoo, Geun-Jong ; Choi, Hoon-Ki ; Choi, Kee-Lim ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 923~932
DOI : 10.3795/KSME-B.2011.35.9.923
Because of the instability of a flow pattern in the inlet transition square duct (hereinafter referred to as "transition duct") of a heat recovery steam generator (hereinafter referred to as "HRSG") in a combined cycle power plant, the Reynolds number in the first row of a tube bank is differs sharply from that in the sectional area of the transition duct. This causes differences in the heat flux in each tube in the tube bank. The computational fluid dynamics (CFD) predictions provide three-dimensional results for velocity, temperature, and other flow parameters over the entire domain of the duct and HRSG. A renormalization group theory (RNG) based k-
�� turbulent model is used for obtaining the results cited in this study. A porous media option is used for modeling the tube banks and the number of transfer units method is used for determining the heat transfer characteristics. This study describes a comparison between the numerical simulation results and actual design output.
Heat Transfer Characteristics with Changing Distances between Burner and Heat Exchanger
Kim, Jong-Min ; Lee, Jae-Park ; Yu, Byeong-Hun ; Kum, Sung-Min ; Lee, Chang-Eon ; Lee, Seung-Ro ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 933~938
DOI : 10.3795/KSME-B.2011.35.9.933
In this study, the heat transfer characteristics and NOx and CO emissions of a heat exchanger were investigated using a premixed burner. The experiments involved changing the distance between the burner and heat exchanger to 30, 40, and 50 mm with various equivalence ratios. The results showed that the NOx and CO emissions increased as the equivalence ratio was increased because the flame temperature increased, regardless of the distance between the burner and heat exchanger. In particular, the CO emission increased significantly as the distance between the burner and heat exchanger was decreased. The optimal equivalence ratio for the A-type heat exchanger (distance between the burner and heat exchanger: 30 cm) was 0.7 in the experimental range. In this case, the CO and NOx emissions were 94.5 ppm and 11.2 ppm, respectively, and the efficiency was 84.1%.
Coal Ash Combustion Simulation for 500-MW Coal-firing Boiler
Hwang, Min-Young ; Jeon, Chung-Hwan ; Song, Ju-Hun ; Kim, Gyu-Bo ; Kim, Seung-Mo ; Park, Myung-Suk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 939~946
DOI : 10.3795/KSME-B.2011.35.9.939
In thermal power generation companies, the recycling of refined ash (LOI < 6%) obtained from a PC-firing furnace is beneficial for the companies, e.g., it can be used for making lightweight aggregates. However, ash having a high LOI, which cannot be reused, is still buried in the ground. To obtain refined ash, the re-burning of high-LOI ash (LOI > 6%) in a PC-firing furnace can be an alternative. In this study, a numerical analysis was performed to demonstrate the effects of ash re-burning. An experimental constant value was decided by TGA (thermo-gravimetric analysis), and a DTF (drop-tube furnace) was used in the experiment for calculating the combustion of ash. On the basis of the trajectory of the moving particles of coal and ash, it was concluded that supplying ash near the burner, which is located high above the ground, is appropriate. On the basis of numerical results, it was concluded that an ash supply rate of 6 ton/h is suitable for combustion, without affecting the PC-firing boiler.
Experimental Study on Auto-Transmission Fluid Heat Exchanger for Improving Vehicle Fuel Efficiency
Jang, Chung-Man ; Lee, Yong-Kyu ; Kang, Byeong-Dong ; Yoo, Jai-Suk ; Lee, Jong-Hwa ; Kim, Hyun-Jung ; Kim, Dong-Kwon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 947~954
DOI : 10.3795/KSME-B.2011.35.9.947
Drive-train friction loss in a vehicle may account for 4% of its total fuel consumption loss. An ATF W/C (auto-transmission fluid warmer/cooler) plate-fin heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between the auto-transmission fluid and coolant. The use of an ATF W/C heat exchanger can result in a fuel economy improvement of about 1% in vehicles. An experimental setup for testing the thermal performance of an ATF W/C plate-fin heat exchanger is developed. In this study, the influence of the ATF and coolant, flow rates, and temperature on the efficiency of an ATF W/C heat exchanger are investigated experimentally. From the experimental data, a simple correlation for predicting the efficiency of an ATF W/C heat exchanger is proposed. On the basis of this correlation, the fuel economy of a vehicle with and without an ATF W/C heat exchanger is compared by using Simulink. Finally, it is shown that the fuel economy is improved by 0.992% when an ATF W/C heat exchanger is installed in the vehicle.
A Feasibility Study on the Energy Harvesting Technology for the Real-Time Monitoring System of Intelligent Railroad Vehicles
Kim, Jae-Hoon ; Lee, Jae-Youn ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 955~960
DOI : 10.3795/KSME-B.2011.35.9.955
This study was aimed at investigating the applicability of energy harvesting technologies, which are regarded as new and renewable energy sources for real-time/wireless monitoring of intelligent railroad vehicles. The surrounding energy generated in a normal operating environment was monitored using a high-speed railroad vehicle in operation. This monitoring was performed in an attempt to evaluate the effectives of energy harvesting and the applicability of energy-harvesting-monitoring technologies under the conditions in which thermal energy and vibration energy are generated.
New Method for Estimating Gas Interchangeability for 13A Gas Appliances
Ha, Young-Cheol ; Park, Seo-Jong ; Park, Won-Sic ; Choi, Kyoung-Seok ; Lee, Chang-Eon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 961~967
DOI : 10.3795/KSME-B.2011.35.9.961
The objective of this study was to develop a new method for estimating gas interchangeability for 13A gas appliances. The three basic principles for the development of this method are as follows: 1) to derive the secondary interchangeability factor that represents the effect of gas composition, in addition to the major interchangeability factor, i.e., Wobbe index; 2) to test every type of and each maker's domestic gas appliances that are widely used in our country, particularly including premixed gas appliances; and 3) to develop a simple estimation method. On the basis of these principles, thirty representative gas appliances were tested, and as a result, a simple two-dimensional interchangeability diagram consisting of Wobbe index and relative density was developed. Unlike conventional methods for estimating interchangeability, this method can be applied to premixed gas appliances, which have a narrow stable flame range, and the interchangeability range of this method then becomes narrower than that of the conventional methods.
Development of Numerical Model for Predicting Deposition Thickness Distribution during Spray Process for Carbon Nanotube Thin Films
Choi, Du-Soon ; Kim, Duck-Jong ; Jang, Dong-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 969~974
DOI : 10.3795/KSME-B.2011.35.9.969
A carbon nanotube (CNT) is a cylindrical carbon nanostructure with good transport properties along the tube's axis. As an approach for realizing the practical use of CNTs, CNT networks are fabricated and their applications in many fields are investigated. To fabricate thin CNT-based films, several methods have been proposed and used. Among these methods, the spray coating method is a robust method for fabricating a large area. However, it is difficult to achieve uniformity in the CNT network. To solve this problem, it is necessary to understand the effect of the sprayprocess parameters on the deposition thickness distribution. In this study, a numerical model for predicting the deposition thickness distribution during the spray process was developed. The spatial deposition thickness distributions obtained according to various nozzle paths were analyzed using the developed numerical model.
Introduction to Flame Transfer Function in Lean Premixed Gas Turbine Combustor
Kim, Dae-Sik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 35, issue 9, 2011, Pages 975~979
DOI : 10.3795/KSME-B.2011.35.9.975
Lean premixed gas turbine combustors were successful in meeting current NOx emission regulations. However, these combustors have been found to be susceptible to combustion instability. In this study, general mechanisms for combustion dynamics and instabilities in lean premixed gas turbine combustors are introduced. In addition, the flame transfer functions in the combustor are experimentally determined. The inputs to the flame transfer function are the imposed velocity fluctuations of the mixture. The key results of the measurements are reviewed.