• Nuclear Engineering and Technology
• /
• 제56권7호
• /
• pp.2524-2533
• /
• 2024

When analyzing containment thermal-hydraulics, computational fluid dynamics (CFD) is a powerful tool because multi-dimensional and local analysis is required for some accident scenarios. According to the previous study, neglecting steam bulk condensation in the CFD analysis leads to a significant error in boundary layer profiles. Validating the condensation model requires the experimental data near the condensing surface, however, available boundary layer data is quite limited. It is also important to confirm whether the heat and mass transfer analogy (HMTA) is still valid in the presence of bulk condensation. In this study, the boundary layer measurements on the vertical condensing surface in the presence of air were performed with the rectangular channel facility WINCS, which was designed to measure the velocity, temperature, and concentration boundary layers. We set the laminar flow condition and varied the Richardson number (1.0-23) and the steam volume fraction (0.35-0.57). The experimental results were used to validate CFD analysis and HMTA models. For the former, we implemented a bulk condensation model assuming local thermal equilibrium into the CFD code and confirmed its validity. For the latter, we validated the HMTA-based correlations, confirming that the mixed convection correlation reasonably predicted the sum of wall and bulk condensation rates.

• Korean Chemical Engineering Research
• /
• 제54권1호
• /
• pp.11-15
• /
• 2016

무인항공기가 장시간 비행하기 위해서는 배터리보다 고분자전해질 연료전지(PEMFC)가 적합하다. 본 연구에서는 PEMFC에 수소를 공급하는 $NaBH_4$가수분해 반응 시스템에 대해 연구하였다. $NaBH_4$가수분해 반응 시스템의 무게를 감소시키기 위해 수소수율 향상, 응축수 회수, 안정적인 수율 유지 등에 대해 실험하였다. 반응기 압력제어를 함으로써 수소 수율을 3.4% 향상시켰다. 수소를 공랭하여 PEMFC 스택에 공급하는 과정에서 발생하는 응축수를 $NaBH_4$ 저장조에 회수하였다. 이 과정에서 응축수가 $NaBH_4$분말을 용해시켜 보충됨으로써 14%의 무게 감량효과가 있었다. 2.0 L/min의 속도로 수소를 발생시킬 때 Co-P-B촉매 2.0 g을 사용해서 10시간동안 96% 수소수율로 $NaBH_4$가수분해 반응 시스템을 안정적으로 구동하였다.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2008년도 춘계학술 발표회
• /
• pp.109-112
• /
• 2008

• 대한수학회지
• /
• 제33권3호
• /
• pp.575-585
• /
• 1996

Recently, existence theorems of coupled fixed points for mixed monotone operators have been considered by several authors (see [1]-[3], [6]). In this paper, we are continuously going to study the existence problems of coupled fixed points for two more general classes of mixed monotone operators. As an application, we utilize our main results to show thee existence of coupled fixed points for a class of non-linear integral equations.

• 대한수학회지
• /
• 제50권1호
• /
• pp.41-59
• /
• 2013

In this paper, we investigate the existence and controllability results for a class of abstract stochastic evolution differential inclusions with nonlocal conditions where the linear part is nondensely defined and satisfies the Hille-Yosida condition. The results are obtained by using integrated semigroup theory and a fixed point theorem for condensing map due to Martelli.

• East Asian mathematical journal
• /
• 제24권4호
• /
• pp.369-375
• /
• 2008

In this paper, we first introduce inwards set valued maps in hyperconvex metric spaces. Then we present fixed point theory for continuous condensing inward set valued maps.

• 약학회지
• /
• 제30권4호
• /
• pp.163-168
• /
• 1986

Thirteen compounds were synthesized by condensing the N-heterocyclic amines (piperidine, pyrrolidine, morpholine) and secondary aliphatic amines (dimethylamine, diethylamine) with 3,4-methylenedioxyphenylalkenoic acid chlorides for developing CNS depressants. Among them, N, N-diethyl-3,4-methylenedioxycinnamamide (IX) and N, N-dimethyl-5-(3,4-methylenedioxyphenyl)-2, 4-pentadienoic acid amicle (XII) exhibited strong activity in antagonism against pentylenetetrazole-induced convulsion, strychnine-induced convulsion and maximal electroshock seizure. N, N-Dimethyl-3, 4-methylenedioxycinnamide (VIII) showed more potent activity in antagonism against strychnine-induced convulsion and maximal electroshock seizure and in the prolongation of hexobarbital sleeping time.

• 대한기계학회논문집
• /
• 제7권3호
• /
• pp.344-352
• /
• 1983

격납 용기 내에 비응축성 가스(공기)가 존재하는 경우에 증기의 응축 열전달 계수를 평가하는 방 법을 연구하였다. 유일한 대규모 격납 용기 실험인 CVTR자료를 이용하여 응축 열전달 계수를 계산하여, 현재 원자력 발전소의 냉각재 상실 사고(LOCA) 및 주 증기 배관 파열사고(MSLB)시에 격납 용기의 안전 해석에서 공식적으로 사용되고 있는 Tagami와 Uchida열전달 계수 관계식과 비교해 본 결과 좋은 일치를 보여 주었다.

• Journal of applied mathematics & informatics
• /
• 제30권1_2호
• /
• pp.57-69
• /
• 2012

In this paper, we prove the existence of mild solutions for a first order impulsive neutral differential inclusion with state dependent delay. We assume that the state-dependent delay part generates an analytic resolvent operator and transforms it into an integral equation. By using a fixed point theorem for condensing multi-valued maps, a main existence theorem is established.

• 충청수학회지
• /
• 제28권2호
• /
• pp.345-352
• /
• 2015

We study the existence of mild solutions of partial neutral integrodifferential equations with unbounded delay by using the fixed point criterion for condensing operators.