• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2019년도 춘계학술논문요약집
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• pp.69-69
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• 2019

The distillation of liquid cathode is necessary to separate cadmium from the actinide elements in the pyroprocessing since the actinide deposits are dissolved or precipitated in a liquid cathode. It is very important to avoid a splattering of cadmium during evaporation due to the high vapor pressure. Several methods have been proposed to lower the splattering of cadmium during distillation. One of the important methods is an installation of crucible cover on the distillation crucible. A multi-layer porous round cover was proposed to avoid a cadmium splattering in our previous study. In this study, the effect of crucible cover on the cadmium distillation was examined to develop a splatter shield. Various surrogates were used for the actinides in the cadmium. The surrogates such as bismuth, zirconia, and tungsten don't evaporate at the operational temperature of the Cd distiller due to their low vapor pressures. The distillation experiments were carried out in a crucible equipped with cover and in a crucible without cover. About 40 grams of Cd was distilled at a reduced pressure for two hours at various temperatures. The mixture of the cadmium and the surrogate was heated at $470{\sim}620^{\circ}C$. Most of the bismuth remained in the crucible equipped with cover after distillation under $580^{\circ}C$ for two hours, whereas small amount of bismuth decreased in the crucible without cover above $580^{\circ}C$. The liquid bismuth escaped with liquid cadmium drop from the crucible without cover. It seems that the crucible cover played a role to prevent the splash of the liquid cadmium drop. The effect of the cover was not clear for the tungsten or zirconia surrogate since the surrogates remained as a solid powder at the experimental temperature. From the results of this work, it can be concluded that the crucible cover can be used to minimize the deposit loss by prevention of escape of liquid drop from the crucible during distillation of liquid cathode.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.111-114
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• 2003

Drop size is one of the most important parameters which are control the performance of the engine using liquid fuel/oxidizer and drop formation is mainly controlled by aerodynamic force caused by ambient gas. Because of this, empirical data and correlation acquired under standard ambient condition are not valid. So experiments under high ambient pressure condition to measure the drop size using image processing method And find the empirical correlation between SMD and chamber pressure(density), injection velocity.

• Journal of information and communication convergence engineering
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• 제4권1호
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• pp.46-52
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• 2006

Precipitation measurement with ground-based radar needs an information of the raindrop size distribution (RSD) characteristics. A 10-month dataset was collected in tropical Atlantic coastal zone of northeastern Brazil where the weather radar was installed. The number of drop was mainly recorded in 300 - 500 drop $mm^{-3}$, of which the maximum was registered around 1.1 mm drop diameter.

• 청정기술
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• 제26권2호
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• pp.102-108
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• 2020

오늘날 석유화학, 정밀화학, 대기오염 방지산업 등에서 증류, 흡수, 추출, 탈거 등 물질분리 단위공정으로 주로 충전탑을 사용해 왔다. 충전탑은 가스-액체, 가스-가스 시스템에서의 물질들과의 접촉에 의해 운전되어 진다. 이러한 충전탑은 낮은 압력손실, 경제적 효율, 고온성 액체물질 적용, 유지보수 용이, 유해가스 처리 등의 운영에서 장점들을 가진다. 충전탑의 성능은 충진물을 통해 가스와 액체를 고르게 분산함으로써 우수한 성능을 보이며, 이는 충전탑 설계에 있어 중요한 인자로 고려되어진다. 본 실험에서는 충진물에 대한 액체부하 및 가스용량인자에 따른 건조압력손실, 수력학적 압력손실, 액체함량 변화에 대한 기하학적 특성에 대하여 연구하였다. 결과로부터 설계인자와 운전조건 등의 유해가스 처리에 필요한 인자를 도출하였다. 임의 충진물인 raschig super-ring에 대한 건조압력손실을 측정한 결과, 가스용량인자가 증가할수록 일정하게 선형적으로 증가하였고, 가스용량인자가 0.630 ~ 3.448 kg^-1/2 m^-1/2 S^-1에서 건조압력손실은 1.892 ~ 47.312 mmH₂O m^-1로 기존 산업현장에서 보편적으로 사용되는 35 mm pall-ring보다도 낮은 압력손실을 보였다. 그리고 raschig super-ring에 대한 수력학적 압력손실을 측정한 결과, 고유 액체부하에 대하여 가스용량인자가 증가할수록 압력손실도 함께 증가함을 확인하였고, 액체부하 변화에 따른 가스용량인자가 1.855 ~ 2.323 kg^-1/2 m^-1/2 S^-1으로 20% 증가할 때, 압력손실은 약 17% 증가하는 것으로 나타났다. 마지막으로, 충진물 체적에 관한 액체함량은 가스용량인자에 의존된 액체부하 매개변수로서 액체부하 변화에 따른 가스용량인자 약 3.84 kg^-1/2 m^-1/2 S^-1까지는 거의 일정한 액체함량을 보였으나, 그 이상에서는 급격하게 증가하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.107-112
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• 2001

The effect of ambient gas (steam) condensation on swirl spray characteristics were studied experimentally for low subcooling condition of the liquid. The configuration of the liquid(water) sheet and the breakup modes were examined. Also variation of the discharge coefficient, breakup length, local and the cross-sectional area-averaged SMD of droplets with the liquid flow(injection) rate were obtained. The perforation breakup mode appears dominant with condensation while the aerodynamic wave breakup mode is dominant without condensation(in the air environment). The discharge coefficient, breakup length and the mean drop sizes decrease in a same manner with increasing of the liquid flow rate for both cases(with and without condensation). The condensation effects are insignificant with the discharge coefficient. However, the local and cross-sectional area-averaged SMD are larger and the breakup length becomes shorter in the steam environment. The spray angle predicted from the volumetric flux distribution along the radial direction of the sprays in the steam environment becomes larger with condensation.

• 한국분무공학회지
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• 제14권2호
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• pp.65-70
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• 2009

An experimental study was performed to explore the atomization characteristics as the drop formation and the liquid breakup of an ethanol fuel using an electrohydrodynamic atomizer. A developed electrohydrodynamic atomizer controlled by a high AC power, a variable frequency, and a liquid feeding was used for the experiments. The test had been considered a disperse atomization processing at $450{\sim}4200V$ applied power, $200{\sim}400\;Hz$ frequency, and $1{\sim}3\;ml/min$ ethanol feeding to achieve an uniformed droplet formation. The goal of the research was to investigate the possibility of the liquid breakup for an ethanol fuel in an electrohydrodynamic atomizer. The results showed that the mean droplet radius decreased as the applied voltage increased or as the applied AC frequency increased. The whipping motion had been grown at the specified voltages due to the applied frequency.

• 한국분무공학회지
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• 제3권1호
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• pp.27-33
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• 1998

Correlations of drop size and velocity in a spray from the disintegration of liquid jet and liquid film from an internal mixing twin-fluid atomizer, were determined by phase Doppler method. The distribution pattern of Sauter mean diameter(SMD) in a spray was changed by a behavior of liquid flow. As smaller droplets became faster and slower easily by the surrounding conditions, the correlation between drop size and mean velocity was found to be varied as next 3 steps; firstly smaller droplets have a higher mean velocity at the area near atomizer, droplets have almost the same mean velocity and finally larger droplets have a higher mean velocity at the area far from an atomizer.

• 한국분무공학회지
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• 제23권4호
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• pp.159-168
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• 2018

Thrust throttling in a liquid rocket engine can be implemented via several ways such as high pressure drop injector, dual manifold, multiple chamber, pintle injector, and gas injection. Thrust throttling using gas injection controls thrust by usually injecting inert gas into propellant through an aerator to reduce the propellant's bulk density. In this study, the outside-in aerator was used in the propellant line to create two phase flow. Closed-type, open-type, and screw-type bi-swirl coaxial injectors were utilized for investigating throttling characteristics such as pressure drop, mixture density, and discharge coefficient according to gas-liquid mass ratio.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.659-662
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• 2002

The present paper presents the experimental results for pressure drop in inclined tube bundles located in a rectangular duct. Measurements are made for pressure drop in triangular and rotated triangular tube arrays having P/d ratio of 1.6 and inclination angles of 30,45,60 and 90 degrees. The Reynolds number based on the free stream velocity and tube diameter ranges from $8{\times}10^2\;to\;6.3{\times}10^{4}$. The experimental results show that the magnitude of dimensionless pressure drop decreases significantly when the inclined angle is less than 45 degree. The measured data are compared with two existing correlations available in the literatures. The ESDU correlation agrees well with the present data far the triangular arrays. But some discrepancies are observed for the rotated triangular arrays when the inclined angles are 30 and 45 degrees. The Idel'chik correlation generally agrees well with the measured data for the rotated triangular arrays except for the inclined angle of 30 degree. The Idel'chik correlation needs modification for the triangular arrays. The modified Idel'chik correlation agrees well with the measured data within $10{\%}$. It is found that the present measured data can be applied to the evaluation and modification of previous correlations.

• 대한의용생체공학회:의공학회지
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• 제23권1호
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• pp.27-32
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• 2002

본 연구에서는 혈관내 혈액 흐름의 압력손실을 최소화하여야 하는 제한 인자를 만족하는 새로운 막형 인공폐에서 액체흐름경향과 중공사 개수에 대한 압력손실 영향을 고찰하고자 하였다 막형 인공폐는 380 $\mu m$의 중공사 외경과 600 mm의 축 방향 길이를 갖는 수 백 개의 중공사로 이루어진 다발이다 중공사 다발은 8가지로 변화시켰으며 흐름은 펌프를 이용하여 조절하였다 혈액대용물질로 글리세롤 용액과 물을 사용하여 압력손실을 측정하였으며 동일한 흐름 경향을 각 중공사들에서 얻었다. 700개의 중공사로 이루어진 막형 인공 폐의 외부 압력손실은 13-16 mmHg이었으며 중공사 개수의 감소에 따른 마찰계수는 중공사와 액체와의 효과적인 접촉이 일어나므로 증가되었다.