• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.45-47
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• 2005

We have investigated the mixing behavior of a tubular heat exchanger reactor using CFD and compared its mixing performance with different type of reactors such as jet mixer and continuous stirred tank reactor (CSTR). The mixedness in each reactor was quantified introducing a statistical average value, the coefficient of variation (CoV), which is a normalized standard deviation of concentration of a component over the whole fluid domain. Through the analysis of the flow pattern and turbulent energy distribution, we suggested a simple but effective way to improve the mixing performance of the tubular heat-exchanger reactor, which include the addition of the internals and/or the increase of the recycle flow rate. It was found that the CoV value of the tubular reactor could be nearly equivalent to that of CSTR by applying those two alternatives suggested here.

• 한국환경과학회지
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• 제6권4호
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• pp.399-407
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• 1997

The pyrolysis reactions of atomic hydrogen with chloroform were studied In a 4 cm 1.6. tubular flow reactor with low flow velocity 1518 cm/sec and a 2.6 cm 1.4. tubular flow reactor with high flow velocity (1227 cm/sec). The hydrogen atom concentration was measured by chemiluminescence titration with nitrogen dioxide, and the chloroform concentrations were determined using a gas chromatography. The chloroform conversion efficiency depended on both the chloroform flow rate and linear flow velocity, but 416 not depend on the flow rate of hydrogen atom. A computer model was employed to estimate a rate constant for the initial reaction of atomic hydrogen with chloroform. The model consisted of a scheme for chloroform-hydrogen atom reaction, Runge-Kutta 4th-order method for Integration of first-order differential equations describing the time dependence of the concentrations of various chemical species, and Rosenbrock method for optimization to match model and experimental results. The scheme for chloroform-hydrogen atom reaction Included 22 elementary reactions. The rate constant estimated using the data obtained from the 2.6 cm 1.4. reactor was to be 8.1 $\times$ $10^{-14}$ $cm^3$/molecule-sec and 3.8 $\times$ $10^{-15}$ cms/molecule-sec, and the deviations of computer model from experimental results were 9% and 12% , for the each reaction time of 0.028 sec and 0.072 sec, respectively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.1948-1952
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• 2007

Heat transfer augmentation based on the process intensification concept in heat exchangers and thermal reactors has received much attention in recent years, mainly due to energy efficiency and environmental considerations. The concept consists of the development of novel apparatuses and techniques that, compared to those commonly used today, are expected to bring dramatic improvements in manufacturing and processing, substantially decreasing equipment size, energy consumption, and ultimately resulting in cheaper, sustainable technologies. The objective of this paper was to investigate the heat transfer characteristics of tubular thermal reactor using static mixing technology. Glycerin and water were used as the test fluids and water was used as the heating source. The results for heat transfer rate were strongly influenced by tube geometry and flow conditions.

• 한국응용과학기술학회지
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• 제28권2호
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• pp.178-184
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• 2011

The analysis of reaction kinetics provided that the reaction order was the $1^{st}$ of triglyceride and the rate constant was 0.067 $min^{-1}$. The transesterification of camelina oil using 0.6 wt% mixed catalyst which consists of 40 v/v% of potassium hydroxide (1 wt%) and 60 v/v% of tetra methyl ammonium hydroxide (0.8 wt%), was carried out at $65^{\circ}C$ on the tubular reactor packed with static mixer. The conversion was shown to be 95.5% at the 6:1 molar ratio of methanol to oil, flow rate of feed of 3.0 mL/min and 24 of element of static mixer. The volume of washing water emitted by 0.6 wt% mixed catalyst was the half of the volume emitted by 1 wt% potassium hydroxide.

• Korean Chemical Engineering Research
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• 제46권5호
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• pp.931-937
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• 2008

공정변수의 변화와 반응기의 성능을 정확하게 예측하기 위하여 Water Gas Shift Reaction(WGSR)을 위한 Multi-Tubular Reactor (MTR)의 상세 multiscale 모델링과 모사를 수행하였다. MTR은 비 균일 고체 촉매로 충진 된 4개의 관형반응기와 냉각을 위해 주변을 싸고 있는 shell side로 구성되어 있다. 유체의 흐름과 반응 kinetics가 반응기 성능에 큰 영향을 주고 있는 점을 고려할 때, Computational Fluid Dynamics (CFD)기법과 공정모델링 기법을 포함한 multiscale 방법론의 채택은 자연스럽고 필수 불가결한 일이다. $345^{\circ}C$로 관형반응기 부분으로 유입된 반응물은 반응의 결과 $390^{\circ}C$로 $45^{\circ}C$가량 온도가 증가하였으며, CO의 전환율은 0.89에 이르렀다. 쉘 사이드로 $190^{\circ}C$로 유입된 유체는 쉘 출구에서 $240^{\circ}C$로 약 $50^{\circ}C$ 가량의 온도 증가를 보였으며 이를 통하여 에너지 절감효과를 가져 올 수 있었으며 높은 전환율을 얻기 위해 반응기 부분의 온도를 적절히 제어할 수 있었다. 모사의 결과는 여러 문헌에 보고된 실험 결과와 매우 근접한 값을 나타내 본 연구를 통해 제시된 모델과 모사의 결과가 정확함을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제13권2호
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• pp.101-109
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• 2002

This work was focused on the thermal decomposition of methane into hydrogen and carbon black without emitting carbon dioxide. Extensive experimental investigation on the thermal decomposition of methane has been carried out using a continuous flow reaction system with tubular reactor. The experiments were conducted at the atmospheric pressure condition in the wide range of temperature ($950-1150^{\circ}C$) and flow rate (250 - 1500 ml/min) in order to study their dependency on hydrogen yield. During the experiments the carbon black was successfully recovered as an useful product. Undesirable pyrocarbon was also formed as solid film, which was deposited on the inside surface of tubular reactor. The film of pyrocarbon in the reactor wall became thicker and thicker, finally blocking the reactor. The design of an efficient reactor which can effectively suppress the formation of pyrocarbon was thought to be one of the most important subjects in the thermal cracking of methane.

• 한국전산유체공학회지
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• 제21권1호
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• pp.43-49
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• 2016

Thermal cracking is commonly modeled as plug flow reaction, neglecting the lateral gradients present. In this paper, 2-dimensional computational fluid dynamics including turbulence model and molecular reaction scheme are carried out. This simulation is solved by means of coupled implicit scheme for stable convergence of solution. The reactor is modeled as an isothermal tube, whose length is 1.2 m and radius is 0.01 m, respectively. At first, The radial profile of velocity and temperature at each point are predicted in its condition. Then the bulk temperature and conversion curve along the axial direction are compared with other published data to identify the reason why discussed variations of properties are important to product yield. Finally, defining a new non-dimensional number, Effect of interaction with turbulence, heat transfer and chemical reaction are discussed for design of thermal cracking furnace.

• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.448-454
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• 2009

Hydrogen was produced from water plasma excited in high frequency (HF) inductively coupled tubular reactor. Mass spectrometry was used to monitor gas phase species at various process conditions, Water dissociation rate depend on the process parameters such as ICP power, $H_{2}O$ flow-rate and process pressure, Water dissociation percent in ICP reactor decrease with increase of chamber pressure, while increase with increase of ICP power and $H_{2}O$ flow rate. The effect of $CH_4$ gas addition to a water plasma on the hydrogen production has been studied in a HF ICP tubular reactor. The main roles of $CH_4$ additive gas in $H_{2}O$ plasma are to react with 0 radical for forming $CO_x$ and CHO and resulting additional $H_2$ production. Furthermore, $CH_4$ additives in $H_{2}O$ plasma is to suppress reverse-reaction by scavenging 0 radical. But, process optimization is needed because $CH_4$ addition has some negative effects such as cost increase and $CO_x$ emission.

• 멤브레인
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• 제20권2호
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• pp.113-119
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• 2010

카놀라유, 대두유, 자트로파유와 메탄올을 연속적으로 분리막 반응기에 순환시켜 바이오디젤을 제조하였다. 분리막은 반응기 역할과 반응 생성물로부터 미반응된 유지를 분리하여 고순도의 fatty acid methyl ester (FAME)를 생산하는 역할을 한다. 공칭 세공크기 0.2, 0.5 ${\mu}m$인 정밀여과형 세라믹 관형 분리막을 사용하였다. 운전압력 0.5 bar에서 0.2 ${\mu}m$ 정밀여과막에 대한 투과유속은 공급유량 400 mL/min일 경우 15 L/$m^2{\cdot}hr$이었다. 또한 투과액중 FAME 함량은 0.5 bar에서 가장 높았으며 운전압력이 증가할수록 감소하였다.

• 한국응용과학기술학회지
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• 제19권4호
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• pp.327-334
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• 2002

Transesterfication of vegetable oils and methanol with alkaline catalyst was carried out to produce biodiesel fuel by continuous process. The process consists of two static mixers, one tubular reactor and two coolers and gave $96{\sim}99$% of methyl ester yield from soybean oil and rapeseed oil. Experimental variables were the molar ratios of methanol to vegetable oil, alkaline catalyst contents, flow rates, mixer element number. The optimum ranges of operating variables were as follows; reaction temperature of $70^{\circ}C$, l:6 of molar ratio of methanol to oil, O.4%(w/w) sodium hydroxide based on oil, static mixer elements number of 24 and 4 min. residence time.