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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 39, Issue 12 - Dec 2015
Volume 39, Issue 11 - Nov 2015
Volume 39, Issue 10 - Oct 2015
Volume 39, Issue 9 - Sep 2015
Volume 39, Issue 8 - Aug 2015
Volume 39, Issue 7 - Jul 2015
Volume 39, Issue 6 - Jun 2015
Volume 39, Issue 5 - May 2015
Volume 39, Issue 4 - Apr 2015
Volume 39, Issue 3 - Mar 2015
Volume 39, Issue 2 - Feb 2015
Volume 39, Issue 1 - Jan 2015
Selecting the target year
Development and Validation of Urea- SCR Control-Oriented Model for NO
Lee, Seung Geun ; Lee, Seang Wock ; Kang, Yeonsik ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 1~9
DOI : 10.3795/KSME-B.2015.39.1.001
To satisfy stricter
emission regulations for light- and heavy-duty diesel vehicles, a control algorithm needs to be developed based on a selective catalytic reaction (SCR) dynamics model for chemical reactions. This paper presents the development and validation of a SCR dynamics model through test rig experiments and MATLAB simulations. A nonlinear state space model is proposed based on the mass conservation law of chemical reactions in the SCR dynamics model. Experiments were performed on a test rig to evaluate the effects of the
concentrations, gas temperature, and space velocity on the
conversion efficiency for the urea-SCR system. The parameter values of the proposed SCR model were identified using the experimental datasets. Finally, a control-oriented model for an SCR system was developed and validated from the experimental data in a MATLAB simulation. The results of this study should contribute toward developing a closed-loop control strategy for
slip reduction in the urea-SCR system for an actual engine test bench.
Numerical Investigation of Deformation of Thin-walled Tube Under Detonation of Combustible Gas Mixture
Gwak, Mincheol ; Lee, Younghun ; Yoh, Jai-Ick ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 11~19
DOI : 10.3795/KSME-B.2015.39.1.011
We present the results of a multi-material numerical investigation of the propagation of a combustible gas mixture detonation in narrow metal tubes. We use an experimentally tuned one step Arrhenius chemical reaction and ideal gas equation of state (EOS) to describe stoichiometric
detonations. The purely plastic deformations of copper and steel tubes are modeled using the Mie-Gruneisen EOS and Johnson-Cook strength model. To precisely track the interface motion between the detonating gas and the deforming wall, we use the hybrid particle level-sets within the ghost fluid framework. The calculated results are validated against the experimental data because the results explain the process of the generation and subsequent interaction of the expansion wave with the high-strain-rate deformation of the walls.
Effect of Reduced Valve Overlap on Emission Characteristics of Hydrogen-Compressed Natural Gas Engine
Lee, Sungwon ; Lim, Gihun ; Park, Cheolwoong ; Choi, Young ; Kim, Changgi ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 21~27
DOI : 10.3795/KSME-B.2015.39.1.021
In order to meet the current emission regulations (EURO-6), it is necessary to significantly reduce
emissions. This study investigated the effect of a reduction in the valve overlap on the combustion and emission characteristics of a hydrogen-compressed natural gas engine under a part-load operating condition. The combustion and emission characteristics were analyzed for each fuel using the original camshaft and an altered camshaft with reduced valve overlap. The results showed that the thermal efficiency was decreased and the fuel flow was increased when using the altered camshaft. The
emissions were increased as a result of the reduced thermal efficiency. Under lean operating conditions, the
emission was decreased compared with one of the conventional camshaft. Thus, under the same fuels and operating conditions, it had a harmful influence on the emission characteristics and thermal efficiency.
Apparatus for Comparing Thermal Conductivity of Nanofluids and Base Fluid Using Simultaneously Measured Resistance Variation Signals from Two Hot Wire Sensors
Lee, Shin Pyo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 29~36
DOI : 10.3795/KSME-B.2015.39.1.029
Exact comparisons of the thermal conductivities of the base fluid and a nanofluid are very important in the early stages of nanofluid development. A simple procedure of measuring the thermal conductivity of the two fluids by the transient hot wire method and numerically dividing these values is used for this purpose. However, because the experiments are not performed simultaneously and the physical properties of the measurement system are sometimes not properly known, large errors are incurred during the evaluation process. This article proposes a new apparatus for thermal conductivity comparison where the working principle is mainly based on relative measurement rather than absolute measurement. The measuring circuit and data processing steps are explained in detail; a validation test was performed using the well-known glycerine and engine oil.
Performance of Heat Recovery System using Evaporative Cooling
Yoo, Seong Yeon ; Kim, Tae Ho ; Kim, Myung Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 37~43
DOI : 10.3795/KSME-B.2015.39.1.037
Evaporative cooling is a very effective way for exhaust heat recovery that uses both latent heat and sensible heat. This study investigated the performance of a heat recovery system using evaporative cooling. The experimental apparatus comprised a plastic heat exchanger, a water spray nozzle, an air blowing fan, a water circulation pump, and measuring sensors for the temperature, humidity, and flow rate. The effectiveness of the sensible heat recovery without evaporation was measured and compared with that of the total heat recovery with evaporation. The effectiveness of the sensible and total heat recoveries decreased as the air flow rate increased, and a much higher effectiveness was obtained with the counterflow arrangement in both cases. For total heat recovery, the effectiveness increased with the water flow rate, and the parallel flow arrangement was found to be more sensitive to the water flow rate than the counterflow arrangement.
Effects of Intake and Exhaust Valve Timing on Combustion and Emission Characteristics of Lean-Burn Direct-Injection LPG Engine
Park, Cheolwoong ; Kim, Taeyoung ; Cho, Seehyoen ; Oh, Seungmook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 45~51
DOI : 10.3795/KSME-B.2015.39.1.045
In order to meet the enforced emission regulations and reduce fuel consumption, various new technologies are employed in engines. The problem of NOx emissions under a lean mixture condition should be solved, because a lean-burn direct-injection engine can realize stable lean combustion with a stratified mixture, which results in improvements in fuel economy and emissions. This study investigated the effects of intake and exhaust valve timing changes on the performance and emission characteristics of a lean-burn LPG direct-injection engine. Under a partial-load operating condition without throttling, an increase in the intake valve opening led to an increase in NOx emissions due to an increase in the amount of excess air. The fuel consumption deteriorated with an increase in the exhaust valve opening due to a decrease in the expansion work and an increase in the pumping loss.
Combustion Characteristics for Co-firing of Biomass (Walnut Shell)
Kim, Jin-Ho ; Lee, Byoung-Hwa ; Sh, Lkhagvadorj ; Kim, Sang-In ; Jeon, Chung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 53~59
DOI : 10.3795/KSME-B.2015.39.1.053
Combustion characteristics for co-firing of biomass (Walnut Shell) as blending fuel in coal fired boiler have investigated using thermogravimetric analyser (TGA) and drop tube reactor (DTR). The results show that devolatilization and char combustion for WS occurs at lower temperature than those of existing coals and has lower activation energy value, which is resulting in higher reactivity. When the WS is blended with coal, TGA results show linear profiles depending on blending ratio for each fuel. However, DTR results exist the non-additive phenomena for blending of WS. As blending ratio of WS increase, the UBC decrease at BBR 5%, but the UBC rather increase from BBR 10% due to oxygen deficiency formed from rapid combustion of WS. This paper propose that fuel lean condition by oxygen rich lead to higher blending ratio of biomass by solving the oxygen deficiency condition.
Mixed Flow and Oxygen Transfer Characteristics of Vertical Orifice Ejector
Kim, Dong Jun ; Park, Sang Kyoo ; Yang, Hei Cheon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 61~69
DOI : 10.3795/KSME-B.2015.39.1.061
The objective of this study is to experimentally investigate the mixed flow behaviors and oxygen transfer characteristics of a vertical orifice ejector. The experimental apparatus consisted of an electric motor-pump, an orifice ejector, a circulation water tank, an air compressor, a high speed camera unit and control or measurement accessories. The mass ratio was calculated using the measured primary flow rate and suction air flow rate with experimental parameters. The visualization images of vertically injected mixed jet issuing from the orifice ejector were qualitatively analyzed. The volumetric oxygen transfer coefficient was calculated using the measured dissolved oxygen concentration. At a constant primary flow rate, the mass ratio and oxygen transfer coefficient increase with the air pressure of compressor. At a constant air pressure of the compressor, the mass ratio decreases and the oxygen transfer coefficient increases as the primary flow rate increases. The residence time and dispersion of fine air bubbles and the penetration of mixed flow were found to be important parameters for the oxygen transfer rate owing to the contact area and time of two phases.
Analysis of Size and Economic Sensitivities according to Changes in Component Replacing Costs of Renewable Hybrid Generation System
Lim, Jong Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 71~78
DOI : 10.3795/KSME-B.2015.39.1.071
This paper presents a method for analyzing the size and economic sensitivity of a new renewable hybrid generation system according to changes in the component replacement costs based on HOMER (Hybrid Optimization Model for Electric Renewables). The design of a hybrid system can be optimized by reducing the size of a sensitive component based on sensitivity analysis using the change in cost of a component. Sensitivity analysis can also provide information on what combinations are necessary for the optimal hybrid system. As an example, sensitivity analysis was performed on the residential load provided by HOMER, and the effects of component replacement costs on the system size and cost were quantitatively analyzed.
Numerical Investigation of Mixing Characteristics in Cavity Flow at Various Aspect Ratios
Shin, Myung Seob ; Yang, Seung Deok ; Yoon, Joon Yong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 79~88
DOI : 10.3795/KSME-B.2015.39.1.079
This study numerically examined the mixing characteristics of rectangular cavity flows by using the hybrid lattice Boltzmann method (HLBM) applied to the finite difference method (FDM). Multi-relaxation time was used along with a passive scalar method which assumes that two substances have the same mass and that there is no interaction. First, we studied numerical results such as the stream function, position of vortices, and velocity profile for a square cavity and rectangular cavity with an aspect ratio of 2. The data were compared with previous numerical results that have been proven to be reliable. We also studied the mixing characteristics of a rectangular cavity flow such as the concentration profile and average Sherwood number at various Pe numbers and aspect ratios.
Experimental Study of Compressor Surge for 250-hp Class Vehicular Turbocharger
Lee, Hyungchang ; Han, Jaeyoung ; Lee, Myeonghee ; Im, Seokyoen ; Yu, Sangseok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 89~95
DOI : 10.3795/KSME-B.2015.39.1.089
A surge phenomenon cause noise and pulsations in a turbo compressor, which is an unstable operating regime. Because surge protection ensures a safe compressor operation, it is important to understand the physics of the surge phenomenon. In this study, the surge characteristics of a 250-hp class turbo-compressor were evaluated experimentally. The experimental parameters were the rotational speed, opening angles of the inlet guide vane and exit valve, and inlet pipe diameter and flow rates of the inlet gases. The results showed that the compressor surge was very sensitive to the gas flow rates, exit pressure, rotational speed, and bypass flow rates.
Approximate Model of Viscous and Squeeze-film Damping Ratios of Heat Exchanger Tubes Subjected to Two-Phase Cross-Flow
Sim, Woo Gun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 97~107
DOI : 10.3795/KSME-B.2015.39.1.097
An analytical model was developed to estimate the viscous and squeeze-film damping ratios of heat exchanger tubes subjected to a two-phase cross-flow. Damping information is required to analyze the flow-induced vibration problem for heat exchange tubes. In heat exchange tubes, the most important energy dissipation mechanisms are related to the dynamic interaction between structures such as the tube and support and the liquid. The present model was formulated considering the added mass coefficient, based on an approximate model by Sim (1997). An approximate analytical method was developed to estimate the hydrodynamic forces acting on an oscillating inner cylinder with a concentric annulus. The forces, including the damping force, were calculated using two models developed for relatively high and low oscillatory Reynolds numbers, respectively. The equivalent diameters for the tube bundles and tube support, and the penetration depth, are important parameters to calculate the viscous damping force acting on tube bundles and the squeeze-film damping forces on the tube support, respectively. To calculate the void fraction of a two-phase flow, a homogeneous model was used. To verify the present model, the analytical results were compared to the results given by existing theories. It was found that the present model was applicable to estimate the viscous damping ratio and squeeze-film damping ratio.
Study on Improvement in Cooled Air Defense Gun System Including Closed Drum Basket
Hwang, Boo Il ; Lee, Dong Hui ; Kim, Chi Hwan ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 1, 2015, Pages 109~113
DOI : 10.3795/KSME-B.2015.39.1.109
Combat vehicles need an air-conditioning unit, although new combat systems tend to use an integrated system for heating, cooling, and ventilating. The specifications of an air-conditioning unit depend on the combat vehicle's purpose. It is difficult to send cooling air from the air-conditioning unit to a gun turret through the drum basket because the gun turret rotates and consists of a closed anti-aircraft shell magazine. In this study, we considered an air-conditioning unit for armored combat vehicle based on the special requirements and military specifications. We evaluated the performance of the air-conditioning unit despite the rotating gun turret through analysis and tests in terms of flow improvement compared to the previous model.