• 한국연소학회지
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• 제7권4호
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• pp.10-20
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• 2002

This paper discusses effect of solid mass inventory on the hydrodynamic characteristics of circulating fluidized bed(CFB). Operating parameters of solid mass inventory and air flow rates were varied to understand their effects on fludization pattern. Experimental measurements were made in a CFB of which height and diameter are 3m and 0.05m respectively. Black SiC particles ranging from $100{\mu}m\;to\;500{\mu}m$ were employed as the bed material. Superficial gas velocity of riser and J-valve fluidizing velocity were in the ranges of $1.39{\sim}3.24m/s\;and\;0.139{\sim}0.232m/s$, respectively. The axial solid fraction and solid circulation rate of CFB were calculated based on the experimental data and compared with modellings through IEA-CFBC Model and commercial CFD code.

• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.103-110
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• 2000

A two phase compound jet, which mixes pulverized solid particles with the air in the test section, is experimentally analyzed in this study. Two phase flow is jetted 10 degree upward in the primary jet, while the secondary jet utilizes the air only. The height difference between the primary and secondary central axises is 32.5mm. The velocity vector field, concentration field, and turbulent properties of solid particles are measured by using 3-Dimensional Particles Dynamics Analyzer. When the jet angle of the secondary jet goes into effect, the solid particle recirculation zone becomes larger. Also, solid particle concentration becomes more dense due to a velocity decrement of particles.

• 설비공학논문집
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• 제2권3호
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• pp.208-217
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• 1990

A rectangular test section is devised by assuming two dimensional melting of a solid phase change material heated from two sides which are maintained at constant temperature and allowing a free expansion due to density difference between solid and liquid. The timewise melting shape is recorded photographically by the shadow graph method for several experimental conditions. The analysis shows that the melting process consists of four regimes. At first, the pure conduction heat transfer is dominant, and as time goes by natural convection grows and plays a role greatly. Experiments are carried out varying not only the wall temperature but height of the wall. Each effect of them on the melting process is obtained in the form of combination of dimensionless parameters, $Ste^{0.8}\;FoRa^{0.2}$. An algebraic correlation is suggested, which predicts the melted fraction well.

• 한국전산유체공학회지
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• 제21권4호
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• pp.90-95
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• 2016

Leidenfrost drops with ellipsoidal shaping can control the bouncing height by adjusting the aspect ratio(AR) of the shape at the moment of impact. In this work, we focus on the effect of the AR and the impact Weber number(We) on the non-axisymmetrical spreading dynamics of the drop, which plays an important role in the control of bouncing. To understand the impact dynamics, the numerical simulation is conducted for the ellipsoidal drop impact upon the perfect non-wetting solid surface by using volume of fluid method, which shows the characteristics of the spreading behavior in each principal axis. As the AR increases, the drop has a high degree of the alignment into one principal axis, which leads to the consequent suppression of bouncing height with shape oscillation. As the We increases, the maximum spreading diameters in the principal axes both increase whereas the contact time on the solid surface rarely depends on the impact velocity at the same AR. The comprehensive understanding of the ellipsoidal drop impact upon non-wetting surface will provide the way to control of drop deposition in applications, such as surface cleaning and spray cooling.

• 한국화재소방학회논문지
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• 제23권1호
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• pp.1-6
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• 2009

본 연구의 목적은 화재 예측모델로 널리 사용되는 FDS(Fire Dynamics Simulation) ver. 4.07을 여객열차 화재예측에 적용하기 위하여 민감도 분석(Sensitivity analysis)을 수행하는 것이다. 주요 분석 변수(Parameter)는 격자 크기(Grid size)와 Solid angle number이다. 분석결과, 격자크기의 변화는 온도(Plume temperature 상부층 온도(Upper layer temperature), 연기층 높이(Layer height)결과 값에 약$10{\sim}20%$의 차이를 갖게 하는 주요 민감도 변수이며 Solid angle number는 민감도에 영향을 크게 미치지 않는 것으로 분석되었다. 또한, 0.05m의 Grid size가 0.1m보다 결과 해상도가 높은 것으로 나타났다.

• Korean Chemical Engineering Research
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• 제43권2호
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• pp.286-293
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• 2005

기체 수송층 흡수탑과 기포 유동층 재생탑으로 구성된 $CO_2$ 회수 공정에 대한 해석의 첫 단계로 이 공정에서 고체 순환특성을 해석하였다. 흡수제 고체 입자에 대한 입도별 물질수지를 해석하여 공정의 흐름에서 고체 흐름량과 입도 분포를 결정하였다. 실험실 규모 공정(흡수탑: 직경 25 mm, 높이 6 m; 재생탑: 직경 0.1 m, 높이 1.2 m)에서 고체순환특성을 모사하였다. 흡수탑의 입도분포는 재생탑의 입도분포와 거의 같았다. 흡수탑에서 유속과 정체층 높이가 증가함에 따라서 고체순환량과 새 흡수제 주입량은 증가하였다. 반면에 흡수탑 내 입자의 평균입경은 감소하였다. 흡수탑사이클론의 절단입도가 증가함에 따라서 고체순환속도는 감소하였으며, 새 흡수제 주입속도와 흡수탑 내 입자의 평균 입경은 증가하였다. 흡수제 입자의 마모계수가 증가함에 따라서 고체순환속도는 증가하고, 새 흡수제 주입속도는 증가하며, 흡수탑 내 입자의 평균입경은 감소하였다.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.186-190
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• 2018

For the first time, the characteristics of solid circulation rate ($G_S$) were investigated in a three-phase (gas-liquid-solid) viscous circulating fluidized bed (TPCFB). The solid circulation rate was controlled separately by adjusting the experimental apparatus as well as operating variables. Effects of primary and secondary liquid velocities ($U_{L1}$ and $U_{L2}$), gas velocity ($U_G$), particle size ($d_p$), height of particles piled up in the solid recycle device (h), and viscosity of continuous liquid media (${\mu}_L$) on the value of $G_S$ were determined. The experimental results showed that the value of $G_S$ increased with increases in the values of $U_{L1}$, $U_{L2}$, h and ${\mu}_L$, while it decreased with increasing $U_G$ and $d_p$ in TPCFBs with viscous liquid media. The values of $G_S$ were well correlated in terms of dimensionless groups within this experimental conditions.

• Near Infrared Analysis
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• 제1권1호
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• pp.23-26
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• 2000

The objectives of this study were to examine the ability to predict soluble solid and firmness in intact apple based on the visible/near-infrared spectroscopic technique. Two cultivars of apples, Delicious and Gala, were handled, tested and analyzed. Reflectance spectra, Magness-Taylor (MT) Firmness, and soluble solids in apples were measured sequentially. Maximum and minimum diameters, height, and weight of apples were recorded before the MT firmness tests. Apple samples were divided in to a calibration set and a validation set. The method of partial least squares (PLS) analysis was used. a unique set of PLS loading vectors (factors) was development for soluble solid and firmness. The PLS model showed good relationship between predicted and measured soluble solids in intact apples in the wavelength range of 860∼1078 nm. However, the PLS analysis was not good enough to predict the apple firmness.

• Korean Chemical Engineering Research
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• 제47권3호
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• pp.355-361
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• 2009

선택적 고체순환을 위한 2탑 유동층 공정에서 고체분리기에 의한 고체분리속도에 미치는 조업변수들의 영향을 측정 및 고찰하였다. 본 연구에서 개발한 고체분리기를 이용하여 굵은입자(212~300 또는 $425{\sim}600{\mu}m$)와 고운입자($63{\sim}106{\mu}m$)의 분리가 가능하였으며 고체분리속도는 66~987 g/min의 범위를 나타내었다. 고체분리속도는 고체분사노즐의 유속, 고체층 높이, 고체분사노즐의 직경, 고운입자와 굵은입자의 입자크기 차이, 고체분리기 금속망 간극크기 및 혼합입자 중 고운입자의 무게분율이 증가함에 따라 증가하였으며 유동화 속도의 영향은 크지 않았다.

• 환경영향평가
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• 제28권5호
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• pp.457-470
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• 2019

서남해 해상풍력 실증단지 해역을 중심으로 구축된 모니터링 자료를 분석하여 해양물리, 해양수질, 해저퇴적물의 환경 특성을 파악하고 현황을 제시하였다. 파고와 부유사 농도, 유속과 부유사 농도의 상관관계를 분석하여 연구 해역 토사의 부유 특성을 고찰하였다. 춘계 시(1 개월) 파고와 부유사 농도 사이에는 상관계수 0.61~0.69의 상관성을 보였으며, 1 m 이상의 높은 파고가 발생하면 75 mg/L 이상의 부유사 농도가 관측되었다. 수질평가지수 산정 시 필요한 항목을 중심으로 수질 현황을 분석하였으며 대부분의 정점에서 1등급(매우 좋음)을 보이고 있었다. 클로로필-a의 변동폭이 다른 항목에 비해 상대적으로 높게 나타나 수질평가지수에 영향을 주는 중요 인자로 파악되었다. 해저퇴적물 내 중금속 현황은 모든 항목의 평균값이 해양환경 주의기준 이하로 검출되었으며 강열감량과 입도분포는 높은 연관성을 보였다.