• Journal of Industrial Technology
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• v.25 no.A
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• pp.191-201
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• 2005

A numerical analysis was done for a tunnel fire in a 1000m road tunnel. A cartesian coordinate was adopted to make a computational grid sytem which has 448,000 computational cells. A transient flow phenomena in the tunnel was simulated by the commercial code of PHEONICS from the ignition of fire to 600 seconds by the interval of 100 seconds. Total computational time of about 44 hours was required to get a convered solution in each time step. The purpose of this research is to analyze of the backlayering pheonomena and recirculation flow in a tunnel. The compuational results say that the backlayering does not happens near the fire of vehicle in this case because the vehicle fire is located at the outside of recirculation zone of flow ocuured near the jet fan. In this research, onset of backlayering pheonomena could be escaped if jet fan is set 95m in front of the the fire of vehicle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.696-701
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• 2018

The nitrogen oxides generated during combustion reactions have a great influence on the generation of acid rain and fine dust. As an NOx reduction method, exhaust gas recirculation combustion using Coanda nozzles capable of recirculating a large amount of exhaust gas with a small amount of air has recently been utilized. In this study, for the burner outlet with dual end opening, the use of a recirculation burner was investigated for the distribution of the pressure, streamline, temperature, combustion reaction rate and nitrogen oxides using computational fluid analysis. The gas mixed with the combustion air and the recirculated exhaust gas flow in the tangential direction of the circular cylinder burner, so that there is a region with low pressure in the vicinity of the fuel nozzle exit. As a result, a reverse flow is formed in the central portion of the burner near the center of the circular cylinder burner and the exhaust gas is discharged to the outside region of the circular cylinder burner. The combustion reaction occurs on the right side of the burner and the temperature and NOx distribution are relatively higher than those on the left side of the burner. It was found that the average NOx production decreased from an air flow ratio of 1.0 to 1.5. When the air flow ratio is 1.8, the NOx production increases abruptly. It is considered that the NOx production reaction increases exponentially with temperature when the air ratio is more than 1.5 and the NOx production reaction rate increases rapidly on the right-hand side of the burner.

• Journal of the Korean Society of Combustion
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• v.7 no.1
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• pp.37-43
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• 2002

Spray characteristics in the swirling flow were investigated by Stereoscopic PIV. Spatial spray structures were measured by PIV as well as PDA in order to understand stable flame stabilization. The feasibility study of Stereoscopic PIV in spray flame was also demonstrated. The size and location of recirculation flow were measured. The stereoscopic PIV could provide 3-D flow fluctuation that cannot be measured by convectional measurement systems.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.101-106
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• 2011

In this study, the velocity distribution according to upper side coner shape of underwater construction with rectangular cylinder was measured with PIV method and the wake flow characteristics was considered. According to the coner shape, the flow pattern of wake flow was also differed greatly and the step-shaped coner of cut-off ratio B/H=0.06 was similar in the slope shape in result.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.249-251
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• 2014

Synthesis gas such as hydrogen and carbon monoxide was produced from $CH_4//oxygen$ mixture using two-section porous media combustor. Heat recirculation through the inner foam structure could extend the flow velocity of stable region over the laminar burning velocity. $H_2/CO$ ratio and module M from concentration of flue gas measured by Gas Chromatography was similar to those calculated by equilibrium. But it was made sure that the heat loss effect becomes more influential than heat recirculation effect as the mixture gets richer. To generate synthesis gas appropriate for methanol production, insulated pressurized porous media combustor will be designed and built in the future.

• International Journal of Automotive Technology
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• v.5 no.3
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• pp.195-200
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• 2004

This paper is concerned with the Homogeneous Charge Compression Ignition (HCCI) engine as a new concept in engines and a power source for future automotive applications. Essentially a combination of spark ignition and compression ignition engines, the HCCI engine exhibits low NOx and Particulate Matter (PM) emissions as well as high efficiency under part load. The objective of this research is to determine the effects of Exhaust Gas Recirculation (EGR) rate on the combustion processes of HCCI. For this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI engine, and a heating device was installed to raise the temperature of the intake air and also to make it more consistent. In addition, a pressure sensor was inserted into each of the cylinders to investigate the differences in characteristics among the cylinders.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.4
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• pp.1-5
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• 2015

In this work, a study was conducted to investigate the effect of diaphragm thickness on the regression rate of the hybrid rocket motor. To observe the flow pattern and the recirculation zone, visualizations of combustion chambers with different diaphragm thickness (5mm, 10mm) were performed. It was found that the case with 5 mm thickness had a larger recirculation zone and therefore, had a higher regression rate than the case with 10mm thickness due to the increased residence time and heat transfer toward the fuel surface. Finally, it was concluded that the thickness of diaphragm can be a critical parameter for the enhancement of the regression rate.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.95-99
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• 2001

As a way to use energy effectively, the present study is aimed at investigating the performance characteristics of a Single Effect LiBr/Water Absorption Refrigerator using a low temperature driving heat-source. It was carried out by changing the driving heat-source temperature, the cold water outlet temperature(the refrigeration load), the cooling water inlet temperature, and the weak solution flow rate and this study compares the performance characteristics of refrigerator against the existence and non-existence of the Recirculation of the Weak solution which is used as a method to improve the performance of refrigerator. In case of Recirculation of the weak solution, more improved the Refrigeration Capacity and COP was obtained, and these effects became more larger in the high temperature of driving heat-source and large quantity of solution.

• Journal of Korea Society of Waste Management
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• v.35 no.8
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• pp.785-798
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• 2018

Since the Framework Act on Resource Circulation was enacted in 2018, the government should establish a National Resource Circulation Master Plan every 10 years, which defines mid- to long-term policy goals and directions on the efficient use of resources, prevention of waste generation and recycling of waste. In addition, we must set mid- to long-term and stepwise targets for the final disposal rate, recycling rate (based on sorted recyclable materials and recycled products), and energy recovery rate of wastes, and relevant measures should be taken to achieve these targets. However, the current industrial waste (IW) statistics have limitations in setting these targets because the final disposal rate and recycling rate are calculated as the ratio of the recycling facility input to the IW generation. In this study, the material flow from the collection stage to the final disposal of industrial waste was analyzed based on the generation of 2016, and the actual recycling amount, actual incineration amount, final disposal amount and their rates were calculated. The effect on the recycling, incineration and final disposal rates was examined by changing the treatment method of nonhazardous wastes from the factory and construction and demolition wastes, which were put in landfills in 2016. In addition, the variation of the waste treatment charge was investigated according to the change of treatment methods. The results of this study are expected to be effectively used to establish the National Resource Circulation Master Plan and industrial waste management policy in the future in South Korea.

• Journal of computational fluids engineering
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• v.11 no.4 s.35
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• pp.32-38
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• 2006

The objective of this study is to evaluate the prediction accuracy of development large eddy simulation(LES) program for turbulent flow behind a bluff-body. The LES solver was implemented on parallel computer consisting 16 processors. To verify the capability of LES code, the results were compared with those of Reynolds Averaged Navier-Stokes(RANS) using standard ${\kappa}-{\varepsilon}$ model as well as experimental data. The results showed that the LES and RANS qualitatively well predicted the experimental results, such as mean axial, radial velocities and turbulent kinetic energy. In the quantitative analysis, however, the LES showed a better prediction performance than RANS. Specially, the LES well described characteristics of the recirculation zones, such as air stagnation point and jet stagnation point. Finally, the unsteady phenomena on the Bluff-body, such as the transition of recirculation region and vorticity, was examined with LES methodology.