• 한국분무공학회지
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• 제11권4호
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• pp.205-211
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• 2006

Impinging angle, impinging distance, length eve. diameter and injection pressure of a triplet injector were tested to evaluate the spray characteristics injected by liquid/gas combinations. Two different kinds of unlike triplet sprays were produced by changing the gas and liquid feed lines. One was the G-L-G(Gas-Liquid-Gas) type, and the other was L-G-L(Liquid-Gas-Liquid) type. Spray angles were wider with the G-L-G type than with L-G-L type. Mass distributions in spray were obtained with a, mechanical patternator. Mass distributions were not circular but elliptical distributions. When the range of mechanical patternator to injector decreased, mass distributions were more concentrated in the center region.

• 한국항공운항학회지
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• 제15권4호
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• pp.1-8
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• 2007

Spray characteristics of a unlike triplet injector were investigated experimentally. Spray images and SMD of droplet were measured to evaluate the spray characteristics injected by liquid/gas combinations. G-L-G(Gas-Liquid-Gas), L-G-L(Liquid-Gas-Liquid) type of injector were used by changing the gas and liquid feed lines. The SMD graph shows that the droplet sizes decrease in the out of radial direction at a fixed gas Reynolds number. The SMD value of decreasing tendency shows that the more ethyl alcohol ratio increase, the more SMD value decrease.

• 공업화학
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• 제33권6호
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• pp.653-660
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• 2022

In liquid hydrogen storage tanks, tank damage or leakage in the surrounding pipes possess a major risk. Since these tanks store huge amounts of the fluid among all the liquid hydrogen process facilities, there is a high risk of leakage-related accidents. Therefore, in this study, we conducted a risk assessment of liquid hydrogen leakage for a grid-type liquid hydrogen storage tank (lattice-type pressure vessel (LPV): 18 m³) that overcame the low space efficiency of the existing pressure vessel shape. Through a commercially developed three-dimensional computational fluid dynamics program, the geometry of the site, where the liquid hydrogen storage tank will be installed, was obtained and simulations of the leakage scenarios for each situation were performed. From the computational flow analysis results, the pool formation behavior in the event of liquid hydrogen leakage was identified, and the resulting damage range was predicted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.131-135
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• 2001

The atomization characteristics of an annular liquid (water) sheet of small radius with a core gas (air) flow were studied. Different sizes of annular gaps (0.2, 0.4 and 0.8 mm) were tested to find the effect of liquid sheet thickness on SMD. The inner diameter of the gas port for the core gas flow was 4 mm. Cross-section averaged SMD was measured for various liquid and gas velocities. Regions of the SMD decrease with the increase of the liquid velocity always existed regardless of the liquid sheet thickness. This attributes to the transition of the flow patterns of spray and also to the aerodynamic interaction between the atomizing gas and the ripples on the liquid sheet surface.

• Korean Chemical Engineering Research
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• 제53권3호
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• pp.315-320
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• 2015

Characteristics of gas-liquid mass transfer and interfacial area were investigated in a bubble column of diameter and height of 0.102 m and 2.5 m, respectively. Effects of gas and liquid velocities on the volumetric gas-liquid mass transfer coefficient ($k_La$), interfacial area (a) and liquid side true mass transfer coefficient ($k_L$) were examined. The interfacial area and volumetric gas-liquid mass transfer coefficient were determined directly by adopting the simultaneous physical desorption of $O_2$ and chemical absorption of $CO_2$ in the column. The values of $k_La$ and a increased with increasing gas velocity but decreased with increasing liquid velocity in the bubble column which was operated in the churn turbulent flow regime. The value of $k_L$ increased with increasing gas velocity but did not change considerably with increasing liquid velocity. The liquid side mass transfer was found to be related closely to the liquid circulation as well as the effective contacting frequency between the bubbles and liquid phases.

• 한국안전학회지
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• 제19권1호
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• pp.1-5
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• 2004

In the present study, the gas injection system based on air-water model was designed to investigate the flow characteristics of liquid phase. A PIV system was applied to analyze the flow pattern in a ladle which gas stated to rise upward from the bottom. Gas flow is one of most important factors which could feature a flow pattern in a gas injection system. As the gas injected into the liquid, the kinetic energy of bubble transfer to liquid phase and a strong circulation flow develops in the liquid phase. Such a flow in the liquid develops vortex and improve the mixing process. Due to the centrifugal force, circulation flow was well developed near both wall sides and upper region respectively. Increasing gas flow was helpful to remove dead zone but, weak flow zone still exists in spite of the increasement of gas flow rate.

• 한국환경과학회지
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• 제3권4호
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• pp.403-408
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• 1994

Catalytic slurry reactors, in which a solid maintained in the rom of fine particles suspended in a liquid, are frequently used in chemical and biochemical and industries. In these processes the particle loading is normally low so that the effects of particles on the liquid-film mass transfer coefacent and the gas-liquid interface area are assumed to be negligible. But it is known from the works, amongst others, that the finely powdered activated carbon can increase the gas-liquid mass transfer significantly in surface-aerated reactors. The stirred cell (13.2cm inside diameter) contained four baffles and at the stirring speeds range of 80 ∼ 300ppm, the gas-liquid interfacial area could be considered as that of the cross section of the vessel (that is, 130.1cm2). When the stirrer speeds were increased, the effective interfacial area was slightly higher than the geometric area and was obtained experimentally from the Danckwerts plots. Key Words : gas-liquid interfacial area, Duckwert's Plot stirred dell. mass transfer coefficient.

• 대한기계학회논문집B
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• 제40권4호
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• pp.227-236
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• 2016

본 논문에서는 $600{\times}600{\mu}m$ 사각 마이크로 채널에서 T자형 합류지점에서의 기체 및 액체의 주입방법이 기포 및 액체 슬러그의 생성에 미치는 영향을 실험을 통해 살펴보았다. 실험 유체로는 질소와 물을 사용하였으며, 액체 및 기체 겉보기 속도는 각각 0.05 - 1 m/s, 0.1 - 1 m/s 의 범위로 테일러 유동이 나타나는 구간에서 데이터를 얻었다. 기포 길이, 액체 슬러그 길이, 기포 속도 그리고 기포 생성 빈도를 고속 카메라를 사용하여 이미지 분석을 통해 측정하였다. 유사한 입구 겉보기 속도 조건에서, T-자형 합류지점의 main channel에 기체를 주입하는 방법(T_gas-liquid)이 액체를 주입하는 방법(T_liquid-gas)보다 기포와 액체 슬러그의 길이가 길었고 기포 생성 빈도는 낮았다. 한편, 두 주입방법에서 기포 속도는 유사하게 나타났다. T_liquid-gas 주입방법의 기존 예측 상관식은 T_gas-liquid 주입방법의 기포 길이, 기포 속도, 액체 슬러그 길이, 기포 생성 빈도 실험데이터를 각각 ~24 %, ~9 %, ~39 %, ~55 %로 예측하였다.

• 한국환경과학회지
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• 제23권3호
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• pp.369-378
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• 2014

Effect of improvement of the dielectric barrier discharge (DBD) plasma system on the inactivation performance of bacteria were investigated. The improvement of plasma reactor was performed by combination with the basic plasma reactor and UV process or combination with the basic plasma reactor and circulation system which was equipped with gas-liquid mixer. Experimental results showed that tailing effect was appeared after the exponential decrease in basic plasma reactor. There was no enhancement effect on the Ralstonia Solanacearum inactivation with combination of basic plasma process and UV process. The application of gas-liquid mixing device on the basic plasma reactor reduced inactivation time and led to complete sterilization. The effect existence of gas-liquid mixing device, voltage, air flow rate (1 ~ 5 L/min), water circulation rate (2.8 ~ 9.4 L/min) in gas-liquid mixing plasma, plasma voltage and UV power of gas-liquid mixing plasma+UV process were evaluated. The optimum air flow rate, water circulation rate, voltage of gas-liquid mixing system were 3 L/min, 3.5 L/min and 60 V, respectively. There was no enhancement effect on the Ralstonia Solanacearum inactivation with combination of gas-liquid mixing plasma and UV process.

• Journal of Korean Society for Atmospheric Environment
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• 제15권E호
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• pp.17-28
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• 1999

Gas-liquid contact tests above a perforated-plate were conducted with air and water at flooding gas-flow conditions in order to study two-phase flow characteristics in a limestone-gypsum SO2 absorber. Gas layers were in the form of air pockets and confined to the limited areas around each duct pipe, while the remaining tary area were in the wet condition. The liquid above the tray was always in the flooded and even fluidized conditions at gas flows over the range studied, although vigorous bubbly or churn-turbulent two-phase regime was only observed in the immediate vicinity of the gas hole exit at low gas loads. The froth zone was extremely active to provide intimate contact between gas and liquid so that the necessary mass transfer operation can take place, which is the primary purpose of high-performance SO2 absorbers. Howefer, the absorber $\Delta$P was 250mmH2O for the initial water level at 150mm, which is an important issue to be resolved for economical operation of the SO2 absorber. It was seen in the liquid level-and gas flow-transient tests that changes in the absorber liquid inventory were much more pronounced for intimate gas-liquid contact than changes in the gas flow. Based on the 4- and 8-duct pipe test results, grouping the duct pipes near the center of the test tray seemed to promote better recirulation of liquid from gas-liquid contact zone back to the reaction tank so that the absorbed SO2 can be neutralized.