• 대한설비공학회지:설비저널
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• 제16권4호
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• pp.383-391
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• 1987

An experimental investigation has been conducted to determine the flow pattern for two-component , two-phase mixtures which flow vertically upwards in concentric annuli based on the measurement for the local void fraction and the distribution of the local void fraction in various radial locations in the annular gap. The annular test section consists of a lucite outer tube whose inside diameter is 38mm and a stainless steel rod, The rod diameter is either :2mm,16mm or 20mm. It is demonstrated that the probability density function of the fluctuations in void fraction may be used as an flow pattern indicator and the local void fraction distribution depends on the flow pattern and radial location in the annular passage.

• 설비공학논문집
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• 제17권5호
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• pp.397-403
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• 2005

The thermal comfort of occupants is directly related to several environmental factors such as velocity of air flow, turbulence intensity and temperature distribution of indoor air. The purpose of this study is to evaluate the indoor air flow and temperature distribution in office area using under-floor air-conditioning system (UFAC System) based on the results from physical measurements and to perform a Computer Fluid Dynamics (CFD) under the same condition of inlet and outlet as field measurement. The results from the CFD simulation are similar to those from the field measurement. The results show that UFAC system is provide proper indoor condition for occupants.

• 한국환경과학회지
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• 제17권7호
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• pp.743-753
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• 2008

Gwangyang Bay is often severely confronted by photochemical pollutants due to its location and dense emissions. It is located in a basin on the south coast of the Korean peninsula and is crossed by a remarkable cluster of hills and mountains of a small horizontal scale that forms a channel. Clearly, the air flow field has a great influence on the dispersion of air pollutants. The characteristics of the wind flow patterns have an important effect on the dispersion of pollutants emitted. In these situations, the distribution of the ozone concentration is extremely complicated because of the superposition of circulations of the air flow fields, especially in complex coastal region. In this study, we examined the distribution of the high level ozone on Gwangyang Bay particularly during the episode day (for 5 years). Among these days, A high level ozone was induced by the development of a sea/land breeze local circulation system, as well as by an anabatic/catabatic flow from the mountains and valley with weakening of the synoptic wind. High level ozone distribution pattern(6 types) on Gwangyang bay is analyzed and the comparison of each pattern reveals substantial localized differences in intensity and distribution of ozone concentration from the site coherence and UPA analysis of ozone concentration. The observed VOC concentration had much difference in concentrations and daily variations between Jungdong and Samil.

• 플랜트 저널
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• 제6권2호
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• pp.62-69
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• 2010

The stability of coal pulverizer in the 800 MW coal-fired plants is vital to maintain their performance. Thus, this study analyzed the uneven abrasion of the deflector and coal spillage due to the air velocity maldistribution in the vane wheel of a bowl-type pulverizer as it is a possible cause for problems of facility using pulverized coal. In addition, air flow in the underbowl of a bowl-type pulverizer was studied to check air velocity maldistribution in the vane wheel using numerical method. In an attempt to correct the maldistribution of air velocity, air flow of the modified duct vane was studied as enlarging the length of the duct vanes installed at the air inlet duct of the pulverizer and increasing the angle of inclination. It was found that modified duct vane make the velocity distribution at the vane wheel uniform. formed by the duct vanes installed at the air inlet duct of the pulverizer and swirling flow is the major factor in making the velocity distribution of vane wheel exit uniform. This can prevent the uneven abrasion of the deflector, which is one of the components inside the pulverizer and coal spillage.

• 설비공학논문집
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• 제20권6호
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• pp.416-426
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• 2008

The boiler tube failure often experienced in the superheater of a utility boiler can seriously affect the economic and safe operation of the power plant. It has been known that this failure is mainly caused by the thermal load deviation in the superheater tube system, and deeply intensified by the non-uniform distribution of steam flow rates. The nonuniform steam flow is distinctively prominent at low power load rather than at full power load. In this paper, we analyze the steam flow distribution in the superheater tube system by using one dimensional flow network model. At 30% power load, the deviation of steam flow rate is predicted to be within 0.8% of the averaged flow rate. This deviation can be reduced to 0.1% and 0.07% by assuming two cases, that is, the removal of 13th tube at each tube rows and the installation of intermediate header, respectively. The assumed two cases would be effective for the uniform steam flow distribution across 85 superheater tube rows.

• 동력기계공학회지
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• 제18권5호
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• pp.35-41
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• 2014

The wood pellet, which is one of the woody biomass energy, has very high economic efficiency and combustion efficiency during their combustion. The existing pellet burner have many problems such as low combustion efficiency, flame stabilization, ash problem and ignition time etc. We developed cyclonic wood pellet burner aim to 20,000kcal/hr boiler and measured temperature profiles and exhaust gases in order to investigate the flame stability and optimum combustion condition at any air flow conditions. As results, we confirmed the reappearance and the isotropy of the experimental results in the burner. At the first air flow inlet condition of excess air ratio ${\alpha}=0.02$, second air flow $490{\ell}/min$ had the best combustion condition when pellet supplied 30g. This result means that we need much air supply only for the swirling of second air flow. So we tested various second air flux at first air excess air ratio ${\alpha}=0.7$ condition. At this condition, we could find out that we don't need much second air and total air flux compared to the former condition. We will continuously test this work of air flow distribution, and swirl effect of first air flow, and ash elimination.

• 설비공학논문집
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• 제20권3호
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• pp.175-180
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• 2008

Flow quantity to supply to a coil in floor heating system is important to achieve comfortable indoor air condition in the winter season. The hot water header is used to distribute the water into the coil. Experimental study has been performed using the water header that have 5 branches consisted of flow control valves and automatic shut-off valves. Each branch line connected it with X-L pipe. Experimental tests accomplished it to investigate the flow distribution characteristics of the hot water header. Experimental results show that the selection of the pump head and differential pressure are very important to save running energy of the system, and high differential pressure needs more friction loss in the case of suitable differential pressure for balancing of the header.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1996년도 추계 학술발표회
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• pp.29-34
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• 1996

In the present paper, the flow distribution in the hot air drying chamber of a sizing machine was numerically analyzed with respect to the geometries of the intake duct to obtain the more uniform flow distribution in the chamber. The result shows that the velocity distribution in the inlet of the chamber was significantly dependent on the the geometry of the intake duct. The degree of the non-uniformity in the chamber was reduced as the incident angle of the intake duct became to be smaller.

• 한국산업보건학회지
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• 제5권2호
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• pp.226-240
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• 1995

This research has a purpose to achieve experimental data used for design of ventilation systems necessary for indoor air quality control and their operation and management. For the study, spatial concentration distribution of indoor air quality according to pollutant site in a simplified model chamber. In low flow ventilation, flow pattern of indoor air was mainly influenced by diffusion and additionally, spatial distribution was formed by convection. Distribution of ventilation efficiency according to each pattern of model chamber was evaluated. It was confirmed that diffusion patterns of a pollutant among sites were formed, centering around main stream areas of supply and exhaust outlets.

• 한국대기환경학회지
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• 제20권3호
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• pp.411-419
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• 2004

Titania particles are widely used as a photocatalyst to treat various contaminants in air and water. Titania particles were formed by vapor-phase oxidation of titanium tetraisopropoxide (TTIP) in a tube furnace between 773 and 1,273 K. The effect of process variables such as furnace temperature, flow rate of carrier air, and flow rate of sheath air on powder size and phase characteristics was investigated using a scanning mobility particle sizer (SMPS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The size distribution of synthesized titania particles was characterized with mode diameter and peak concentration. The mode diameter ranging from 20 to 80 nm decreased with increasing flow rates of sheath air and carrier air, and increased with increasing furnace temperature. The peak concentration increased with increasing flow rates of sheath air and carrier air The best synthetic condition for high production rate can be derived from the experimental data set represented by mode diameter and peak concentration. The crystal structure of synthesized titania particles was found to be anatase phase, ensuring high photocatalytic potential.