• 한국가스학회지
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• 제18권4호
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• pp.56-62
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• 2014

본 연구에서는 촉매가 들어있는 고정층 반응로의 단일 개질관에 대하여 전산 유체 해석(Fluent ver. 13.0)을 수행하여 열/유동 특성을 파악하고, 주입 가스에 따른 추출 가스의 종류를 다공성에 따라 예측하였다. 촉매 형상을 모델링하기 위하여, 개질관 내부에 있는 촉매를 모두 다공성 물질이라고 가정하고, 수정된 Eugun 식을 해석에 적용하였다. 유체의 공극률을 기준으로 0.545, 0.409, 그리고 0.403로 설정하고, 결과를 비 다공성인 경우와 비교하였다. 수치해석 결과, 개질관 벽면의 온도는 흡열반응과 주변 열전달로 인하여 개질관의 온도보다 높게 나타나며, 수소 생성량도 다소 증가했다. 촉매의 공극률이 증가 하게 될 경우, 압력 강하로 인하여 관 중심부 온도 및 수소 생성량이 현저하게 감소하는 경향을 보였다.

• 공업화학
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• 제27권2호
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• pp.199-204
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• 2016

입상 활성탄을 사용하여 수용액으로부터 Rhodamine-B 염료의 흡착에 대해 조사하였다. 회분식 실험은 흡착제의 양, pH 초기농도와 접촉시간과 온도를 흡착변수로 사용하여 수행하였다. 흡착평형자료는 Langmuir 등온식에 잘 맞았다. 평가된 Langmuir 분리계수($R_L$ = 0.0164~0.0314)로부터 이 흡착공정이 적절한 처리방법이 될 수 있음을 알았다. 흡착속도실험결과는 유사 1차 반응속도식에 잘 맞는 것으로 나타났다. 음수값의 Gibbs 자유에너지(-4.51~-13.44 kJ/mol)와 양수값의 엔탈피(128.97 kJ/mol)는 흡착이 자발적이고 흡열공정으로 진행된다는 것을 나타냈다. 등량흡착열은 흡착된 염료분자들의 측면상호작용에 따라 표면부하량이 증가할수록 커졌다.

• 한국수소및신에너지학회논문집
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• 제30권3호
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• pp.201-208
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• 2019

Recently, a fuel reforming plant for supplying high purity hydrogen is being applied to submarines. Since steam reforming is an endothermic reaction, it is necessary to continuously supply heat to the reactor. A fuel reforming plant for a submarine needs a multi-stage burner (MSB) to acquire heat and convert the combustion gas to $CO_2+H_2O$. The MSB has problems that the combustion imbalance occurs during start-up due to the temperature restriction of the combustion gas. This problems can be solved by burning $H_2O$ together with fuel and $O_2$. In this study, the simulation results of MSB were analyzed to determine the optimum flow rate of $H_2O$ supplied to the 6-stage burner. When the flow rate of $H_2O$ was low, combustion was concentrated on the burner#6 in comparison with the burner#1-#5. This combustion concentration improved as the supply amount of $H_2O$ increased. As a results, it was necessary to supply at least 4.9 kmol/h of $H_2O$ (per 1 kmol/h of fuel) to burner#1 in order to maintain the combustion gas temperature of each stage at $750^{\circ}C$ and to convert the final stage burner gas composition to $CO_2+H_2O$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.156.1-156.1
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• 2011

It is of great importance to predict operating parameter characteristics of an integrated fuel processor by the increased life-time and system performance. In this study, computational analysis is performed to gain fundamental insights on transport phenomena and chemical reactions in reformer which consists of preheating, steam reforming, and water gas shift reaction beds. Also, a top-fired burner locates inside of the reforming system. The combustor is providing thermal energy necessary for the steam reforming bed which is a endothermic catalytic reactor. Two-dimensional numerical model of the integrated fuel processing system is introduced for the analysis of heat and mass transport phenomena as well as surface kinetics and catalytic process. A kinetic model was developed and then computational results were compared with the experimental data available in the literature. Subsequently, parameter study using the validated steam methane reforming model was conducted by considering operating parameters, i.e. steam to carbon ratio and temperature.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.614-618
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• 2005

The complex of the composition LaL(N$O_3)_3\;(H_2O)_2$ is prepared by the reaction of La($NO_3)_3{\cdot}6H_2O$ with Nethylmorpholine in aqueous medium. The ligand is involved in the complex as a neutral species where the chelation occurs via the oxygen of the ligand moiety and the nitrate groups as bidentate ligand. The chemical structure of the studied complex is confirmed through IR, XRD, and thermal analysis data. The complexation equilibria of La(III) with N-ethylmopholine is studied in aqueous medium at ionic strength I = 0.1 mol${\cdot}dm^{-3}\;KNO_3$ and at 25, 35 and 45 ${^{\circ}C}$, respectively. The thermodynamic parameters $\Delta$G, $\Delta$H and $\Delta$S values were calculated to prove the association with the complex formation. It is clearly observed that the process is accompanied by absorption of heat, i.e. endothermic process, while the entropy does not change greatly attributed to the release of constant number of water molecules during chelate formation.

• 한국수소및신에너지학회논문집
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• 제20권4호
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• pp.337-343
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• 2009

Noncatalytic partial oxidation of methane for producing synthesis gas was studied in a lab-scale experimental apparatus. Partial oxidation developed for high-temperature, fuel-rich combustion and it is exothermic process. but Steam reforming and Caron reforming is highly endothermic process to need much energy. Noncatalytic partial oxidation of methane is affected by temperature and equivalent ratio, so we studied effect about composition of synthesis gas at lab scale reactor. We used electronic heater to control the temperature of reactor. The quality of synthesis gas is improved and reduced heat value to require at Noncatalytic partial oxidation because the reacting temperature is lower at oxy condition.

• 한국화재소방학회논문지
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• 제25권5호
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• pp.69-75
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• 2011

수산화마그네슘을 첨가한 저밀도 폴리에틸렌-에틸렌 비닐 아세테이트 복합체의 연소성을 시험하였다. 저밀도 폴리에틸렌-에틸렌 비닐 아세테이트에 수산화마그네슘을 40~80 wt% 첨가하여 용융 혼합하고 성형 후 콘칼로리미터(ISO 5660-1)를 이용하여 연소성을 시험하였다. 수산화마그네슘을 첨가한 시편은 첨가하지 않은 시험편에 비하여 그의 플래시오버 가능성이 감소하였다. 이것은 순수한 저밀도 폴리에틸렌-에틸렌비닐 아세테이트에 첨가한 수산화마그네슘의 흡열 분해 때문에 연소 억제성이 향상된 것으로 생각된다. 수산화마그네슘을 첨가한 시험편은 첨가하지 않은 시험편에 비해 낮은 총열방출량과 낮은 CO 발생량을 나타내었고, 수산화마그네슘 함량이 증가할수록 총연기발생량과 비소화면적이 감소하였다.

• Macromolecular Research
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• 제15권7호
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• pp.623-632
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• 2007

Thermosensitive nanoparticles were prepared via the self-assembly of two different $poly({\varepsilon}-caprolactone)$-based block copolymers of poly(N-isopropylacrylamide)-b-$poly({\varepsilon}-caprolactone)$ (PNPCL) and poly(ethylene glycol)-b-$poly({\varepsilon}-caprolactone)$ (PEGCL). The self-aggregation and thermosensitive behaviors of the mixed nanoparticles were investigated using $^1H-NMR$, turbidimetry, differential scanning microcalorimetry (micro-DSC), dynamic light scattering (DLS), and fluorescence spectroscopy. The copolymer mixtures (mixed nanoparticles, M1-M5, with different PNPCL content) formed nano-sized self-aggregates in an aqueous environment via the intra- and/or intermolecular association of hydrophobic PCL chains. The microscopic investigation of the mixed nanoparticles showed that the critical aggregation concentration (cac), the partition equilibrium constants $(K_v)$ of pyrene, and the aggregation number of PCL chains per one hydrophobic microdomain varied in accordance with the compositions of the mixed nanoparticles. Furthermore, the PNPCL harboring mixed nanoparticles evidenced phase transition behavior, originated by coil to the globule transition of PNiPAAm block upon heating, thereby resulting in the turbidity change, endothermic heat exchange, and particle size reduction upon heating. The drug release tests showed that the formation of the thermosensitive hydrogel layer enhanced the sustained drug release patterns by functioning as an additional diffusion barrier.

• 한국수소및신에너지학회논문집
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• 제25권4호
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• pp.364-377
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• 2014

The performances of a coupled reactor in which a steam reformer and a catalytic combustor were mounted simultaneously had been investigated and compared. The combustible offgas exhausted from the anode of SOFC and MCFC were utilized as heat sources for the endothermic steam methane reforming. The catalytic combustion was used in order to burn the combustible offgas. Thermal energy released by the catalytic combustion is directly transferred to the reformer surrounding the combustor. The various operational conditions such as fuel utilization rate, steam to carbon ratio, amount of catalysts, fuel cell loads were changed. And operating variables were comprehensively identified by sensitivity analysis. The fundamental results from this experimental study show the potential abilities of the coupled reactor. Therefore the results will be of help to design and manufacture the more better coupled reactor in the future.

• 한국기계가공학회지
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• 제21권3호
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• pp.110-117
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• 2022

A chiller cooler absorbs the thermal energy of water to generate cold water and supplies the generated cold water to a cold water pipe buried in the wall of a small mobile modular house to greatly increase the cooling area. An attempt was made to reduce the required cooling time significantly. A small chiller cooler suitable for the cooling load of a small mobile modular house with an area less than 3.3 m² was employed. When cooling is done during summer using a chiller cooler installed outdoors, heat absorption energy loss occurs in the cold water pipe owing to the high temperature. To address this, a study was conducted to reduce the endothermic energy loss significantly. As the mass flow rate of the cold water flowing inside the cold water pipe increased, the temperature decrease gradient of the cold water increased. From the start of the cooling operation, the air temperature of the small mobile modular house decreased linearly in proportion to the operation time. Furthermore, the temperature of the air inside the small mobile modular house decreased in proportion to the increase in the flow of water inside the cold water pipe.