• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.262-267
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• 2016

This paper describes a design of a hair drier to improve its performance. the performance of the hair drier can be improved by increasing the wind velocity of its discharge port. the design of the hair drier is accomplished by using the CFD. the validity of design results were verified by comparison with the dry change of the hair drier. In this paper, the initial condition of the applied hair drier is as follows, the number of the blade is 9, the diameter of the suction port is 40[mm], the tip clearance is 12.5[mm], the con angle is $28.5^{\circ}$ and the fan angle is 27.5R. From design results, the enhanced condition of the hair drier can be obtained as follows, the number of the blade is 3, the diameter of the suction port is 50[mm], the tip clearance is 10.5[mm], the con angle is $21.5^{\circ}$ and the fan angle is 75R. At the enhanced condition of the hair drier, the wind velocity of the hair drier is 29[%] increase, and the dry time is 40[%] increase compare to the initial condition of the hair drier.

• Atmosphere
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• v.21 no.1
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• pp.95-108
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• 2011

The effects of an apartment complex on flow and pollutant dispersion in an urban area are numerically investigated using a computational fluid dynamics (CFD) model. The CFD model is based on the Reynolds-averaged Navier-Stokes equations and includes the renormalization group k-${\varepsilon}$ turbulence model. The geographic information system (GIS) data is used as an input data of the CFD model. Eight numerical simulations are carried out for different inflow directions and, for each inflow direction, the effects of an apartment complex are investigated, comparing the characteristics of flow and dispersion before and after construction of the apartment complex in detail. The observation data of automatic weather system (AWS) is analyzed. The windrose analysis shows that the wind speed and direction after the construction of the complex are quite different from those before the construction. The construction of the apartment complex resulted in the decrease in wind speed at the downwind region. It is also shown that the wind speed increased partially inside the apartment complex due to the channeling effect to satisfy the mass continuity. On the whole, the wind speed decreased at the downwind region due to the drag effect by the apartment complex. As a result, the passive pollutant concentration increased (decreased) near the downwind region of (within) the apartment complex compared with that before the construction.

• Land and Housing Review
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• v.10 no.2
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• pp.53-58
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• 2019

Particulate matter (PM) is designated as a group 1 carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). In South Korea, the health threat caused by PM is the most serious level internationally. Therefore, in order to solve the urban PM problem, it is important to develop the technology that can control PM efficiently. In this study, CFD(Computational Fluid Dynamics) simulation was performed for PM pre-filter (type 1-3 with different PM collecting room) to develop a high-efficiency PM collecting device. The complex flow field and the local flow phenomenon inside the PM collecting device were understood with CFD simulation by changing the shape and size of the pre-filter. The PM removal performance can be described with flow rate through the device and PM removal efficiency. The type-1 pre-filter with 5x5 size collecting room was confirmed to have the highest efficiency. Based on the analysis results, the optimal type of pre-filter could be developed and it would be applied as an element technology included in the PM collecting device.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.7
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• pp.673-680
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• 2009

In this study, die cooling system using the nitrogen gas has been applied to hot aluminum extrusion process for refining grains and reducing of grain growth. Computational fluid dynamics(CFD) has been carried out to evaluate die cooling effect by nitrogen gas, and the results of CFD have been used to FE-simulation for the prediction of the extrudate temperature in hot extrusion process. Experimental hot extrusion has been performed to observe microstructure and to measure temperature of extrudate. The results of FE-Simulation have been good agreement with those of experiment. Finally, process condition of hot extrusion can be established to reduce grain growth of Al6061 through the experiment.

• Plant Journal
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• v.9 no.3
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• pp.48-52
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• 2013

In this study, the internal flow field of SCR Denitrification Plant was simulated by using Computational Fluid Dynamics(CFD). In order to analyze the uniformity of flow field, an interpretation on the pre-existing facilities was performed, and some moot points were identified and compensated through this analysis. The compensatory methods include the installation of the Porous Plate below the bottom of the Baffle to create uniform flow and also, and the Guide Vane was also placed in the bend of pipe to guide the flow uniformly. Lastly, the Baffle was installed to deduct equalized space distribution of the air flow, initially flowed into the SCR Plant.

• Journal of Biosystems Engineering
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• v.35 no.6
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• pp.393-400
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• 2010

Uniform and rapid pre-drying of mandarin is important to improve the storage quality. The aim of this study was to suggest the basic design of forced ventilated pre-drying facility for mandarin by thermal flow analysis using computational fluid dynamics software (FLUENT 6.2). Developed CFD simulation model was verified by comparison with experimental data. Airflows and temperature distributions in the five conceptional designs including existing ordinary temperature storage rooms were analyzed and appropriate basic design was determined. Analysis of the effect of arrangement of windows and exhaust fans on thermal flow in facility was carried out for more detailed design. The results of this investigation showed that the predicted airflow velocity by CFD simulation showed a good agreement with the measured value and optimum design condition for simulated forced ventilated pre-drying facility of mandarin has two exhaust fans and two windows on both sidewalls and cover on loaded mandarin.

• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.85-90
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• 2014

Turbo chiller is widely used for the air conditioner and uses hydrochlorofluorocarbon 123 (HCFC-123) as a refrigerant. HCFC-123 is one of the chemicals being considered as a replacement for the chlorofluorocarbons. High concentrations of HCFC-123 cause a deficiency of oxygen with the risk of unconsciousness or death, the vapour is heavier than air and may accumulate in low ceiling spaces causing deficiency of oxygen. In this study, the concentration distribution of oxygen indoor was investigated by using computational fluid dynamics(CFD) as four workers were killed in HCFC-123 gas leaks at machine room of hypermarket in 2011.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.745-753
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• 2016

The objective of this study was to investigate design factors of the electrolysis reactor through the CFD(computational fluid dynamics) simulation technique. Analyses of velocity vector, streamline, chloride ion concentration distribution showed differences in flow characteristics between the plate type electrode and the porous plate type electrode. In case of the porous plate type electrode, chlorine gas bubbles generated from the anode made upward density flow with relatively constant velocity vectors. Electrolysis effect was more expected with the porous plate type electrode from the distribution of chloride ion concentration. The upper part of the electrolysis reactor with the porous plate type electrode had comparatively low chloride concentration because chloride was converted to the chlorine gas formation. Decreasing the size and increasing total area of rectifying holes in the upper part of cathodes, and widening the area of the rectifying holes in the lower part of cathodes could improve the circulation flow and the efficiency of electrolysis reactor.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.277-282
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• 2006

In order to predict the indoor air pollutant, the VOCs emission rate is used through small chamber in the design process. However, the small chamber method has limitations as the convective mass transfer coefficient, the most important factor when predicting VOCs contamination of indoor air, is different between the small chamber result and the measured data in the actual building. Furthermore, the existing studies which analyzed mass transfer coefficient in the small chamber were directed on the small chambers developed at the time and FLEC(Field and Laboratory Emission Cell), thus, are different from the current small chamber which has been changed with improvements. The purpose of this study is to determine the emission rate of pollutant in double-layered building materials through the CFD(Computational of Fluid Dynamics) and Numerical analysis based on the mass transfer coefficient on singled-layered building material by using the current small chamber widely used in Korea. Futhermore, this study used the new convective mass transfer coefficient($h_m'$) which indicates the existing convective mass transfer coefficient($h_m$) including VOC partition coefficient(k). Also, formaldehyde was selected as target pollutant.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.614-621
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• 2020

Recently, as the fine dust is increased and the emission regulations of diesel engines are strengthened, interest in diesel soot filtration devices is rapidly increased. In particular, there is a demand for technology development for higher efficiency of diesel exhaust gas after-treatment devices. As part of this, many studies conducted to increase the exhaust gas treatment efficiency by improving the flow uniformity of the exhaust gas in the DPF and reducing the pressure drop between the inlet and outlet of disel particle filter (DPF). In this study, computational fluid dynamics (CFD) simulation was performed when exhaust gas flows into the canning reduction device equipped with a 13" asymmetric DPF in order to maintain the flow uniformity in the diesel exhaust system and reduce the pressure. In particular, a study was conducted to find the geometry with the smallest pressure drop and the highest flow uniformity by simulating the DPF I/O ratio, exhaust gas temperature, inlet-outlet pressure and flow uniformity according to the geometry and hole size of distributor.