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- 주제어 : overall mass transfer coefficient (검색결과 11 건)
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Hadi Poortalari,Javad karimi Sabet,Farshad Varaminian 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.5
A simple non-equilibrium modeling approach is proposed to simulate multicomponent distillation process in packed columns. The real behavior of the column is simply considered by the evaluation of interphase mass transfer rate based on the overall mass transfer coefficient. Two distinct methods are used to calculate this overall coefficient including the effective mass transfer coefficient method and the packing efficiency method. The modelling procedure consists of an iterative segment-wise algorithm implemented in a MATLAB home-code. For verification, the obtained composition profiles from a structured and a random packed column are compared with reported experimental data. Comparisons show that the packing efficiency-based model could acceptably predict the experimental profiles with an average relative deviation of 18% and 25% for structured and random packed columns, respectively. This confirms that our simple non-equilibrium approach is a reliable and robust model for the performance evaluation of packed columns.
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3-메틸아미노프로필아민과 N-메틸-2-피롤리돈을 포함한 저수계 흡수제의 CO2 포집 특성
홍연기,왕슈아이,홍정현,유정균 한국화학공학회 2023 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.61 No.4
Conventional aqueous amine-based CO2 capture has a problem in that a large amount of renewable energy is required for CO2 stripping and solvent regeneration in its industrial applications. This work proposes a water-lean absorbent that can reduce regeneration energy by lowering the water content in the absorbent with high absorption capacity for CO2. To this purpose, this water-lean solvent introduced NMP (N-methyl-2-pyrrolidone), which has a higher physical solubility in CO2 and a low specific heat capacity comparing to water, along with 3-methylaminopropylamine (MAPA), a diamine, into the absorbent. The circulating absorption capacity and absorption rate for CO2 of this water-lean solvent were measured using a packed tower. When NMP was added to the absorbent, the absorption rate was improved. In the case of the absorbent containing 2.5M MAPA was used, the maximum circulating absorption capacity was obtained when 10 wt% of NMP was included in absorbent. The overall mass transfer coefficient increased as the concentration of NMP increased. However, at loading values higher than 0.5, the increment in mass transfer coefficient decreased as the concentration of NMP increased. When the lean loading value is low, the mass transfer resistance due to viscosity of the absorbent is low, so the overall mass transfer coefficient increases with the addition of NMP. However, as the lean loading value increases, the viscosity of the absorbent increases, and the diffusivity of CO2 and MAPA decreases, resulting in sharply decreasing of the overall mass transfer coefficient.
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젖은 벽탑을 이용한 디에틸렌트리아민과 디에틸에탄올아민 수용액의 CO<sub>2</sub> 흡수속도 측정
유정균 ( Jong Kyun You ),이준 ( Jun Lee ),홍연기 ( Yeon Ki Hong ) 한국화학공학회 2022 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.60 No.4
Biphasic solvents are attracting attention as energy-reducing solvents for capturing CO<sub>2</sub> from flue gas in combustion process. In this study, considering diethylenetriamine (DETA) and diethylethanolamine (DEEA) mixed solvents, one of the biphasic solvents by blending of two types of amines, the CO<sub>2</sub> absorption rates of DETA and DEEA was measured by wetted wall column. The effects of DETA and DEEA concentrations and operating temperature on the overall mass transfer coefficient were investigated. As a result, the overall mass transfer coefficient was proportional to the DETA concentration. However, in the case of the DEEA concentration, the effect was small and when the concentration was exceeded, the overall mass transfer coefficient decreased. The DETA aqueous solution showed little change in the overall mass transfer coefficient with the operating temperature, whereas the DEEA aqueous solution increased the overall mass transfer coefficient with the operating temperature. As a result of obtaining the observed reaction rate constant under the pseudo-first-order reaction assumption, it was found that the observed reaction rate constant in DETA aqueous solution was proportional to the DETA concentration, but DEEA did not fit the pseudo-firstorder reaction assumption.
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β-Glucan 추출에 미치는 온도, 용매 농도 및 pH의 영향
이상훈,장귀영,김기종,이미자,김태집,이준수,정헌상,Lee, Sang Hoon,Jang, Gwi Yeong,Kim, Kee Jong,Lee, Mi Ja,Kim, Tae Jip,Lee, Junsoo,Jeong, Heon Sang 한국식품영양학회 2012 韓國食品營養學會誌 Vol.25 No.4
This study investigated the effects of temperature, solvent concentration, and pH on the ${\beta}$-glucan extraction. Oat bran ${\beta}$-glucan was extracted with different extraction conditions, using various combinations of experiment factors, such as temperature (40, 45, 50, 55, and $60^{\circ}C$), ethanol concentration (0, 5, 10, 15, and 20%), and pH (5, 6, 7, 8, and 9). Under the various extraction conditions, ${\beta}$-glucan extraction rate and overall mass transfer coefficient of oat bran ${\beta}$-glucan, and viscosity of oat bran extracts were investigated. As increasing the extraction time, the extraction rate of ${\beta}$-glucan increased. The overall mass transfer coefficient of ${\beta}$-glucan ranged from $3.36{\times}10^{-6}$ to $8.55{\times}10^{-6}cm/min$, indicating the lowest at the extraction condition of $45^{\circ}C$, 15% and pH 8, and the highest at $50^{\circ}C$, 0% and pH 7. It was significantly greater with increasing extraction temperature and decreasing ethanol concentrations of extraction solvent, except for solvent pH. There were positive correlations among the overall mass transfer coefficient, the extraction rate of ${\beta}$-glucan, and the viscosity of extract.
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M. M. A. Sarker,김은필(E. P. Kim),문춘근(C. G. Moon),윤정인(J. I. Yoon) 한국동력기계공학회 2005 동력시스템공학회지 Vol.9 No.2
The experiment of thermal performance about closed-wet cooling tower was conducted in this study. A closed cooling tower is a device similar to a general cooling tower, but with cooling tower replaced by a heat exchanger. The test section for this experiment has the process that the cooling water flows from the top of the heat exchanger to the bottom side in the inner part of the tube, and spray water flows in the gravitational direction in the outer side. Air comes in direct contact with the spray water at the outer side of the tube while passing from the lower the upper part having a counterflow to the spray water. The heat transfer pipe used in this experiment is a bare-type tube having an outer diameter of 15.88mm. The heat exchanger is consisted of seven rows and fifteen columns. In this experiment, thermal performance of the cooling tower is derived from overall heat transfer coefficients between the process fluid and sprayed water and volumetric overall mass transfer coefficient between sprayed water and air.
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내부순환반응기의 scale-up에 따른 동력학적 특성의 변화
최윤찬,박영식,서정호,김동석,송승구 한국환경과학회 1997 한국환경과학회지 Vol.6 No.1
The variations of gas hold-up, overall volumetric oxygen mass transfer coefficients and liquid circulation velocity in an internal loop reactor were investigated to manifest scale-up effect. The relationship between superficial gas velocity and gas hold-up were found as Ugr = 0.045 εr in the pilot-scale and Ugr = 0.056 εr in the bench-scale reactor. The overall volumetric oxygen mass transfer coefficient, K_La was slightly increased in the pilotscale than in the bench-scale reactor. Flow regime was changed from the bubble flow to the churn-turbulent flow when the superficial gas velocity reached to 3.5 - 4 ㎝/sec in the pilot-scale.
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