• Journal of Energy Engineering
• /
• v.2 no.1
• /
• pp.75-82
• /
• 1993

A 50 ㎾ phosphoric acid fuel cell(PAFC) system using natural gas was simulated for steady state with the commercial software, ASPEN PLUS. The USER block and the FORTRAN block were prepared to simulate the cell. The changes of hydrogen yield according to the variation of several operating conditions were examined and the operating conditions to maximize hydrogen yield were obtained. The simulation results agree with the real data, which can be used to prepare the basic process data and the optimal conditions for the domestic commercial fuel cell system. H$_2$utilization rate over 50% should be maintained to achieve the efficiency of the conventional electricity generation. Energy consumption can be reduced by utilizing the heat released from the reformer and the cell which are operated at high temperatures.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.2
• /
• pp.24-33
• /
• 2021

Numerical study is conducted to analyze combustion instability in the partially premixed combustor. The simulations are performed according to fuel conditions, and Large Eddy Simulation(LES) model and PaSR combustion model are implemented in the solver. Comparison with the experimental result is conducted to confirm the validity of simulation, and quantitative and qualitative agreement is confirmed. The flame characteristics in the combustor are subsequently investigated, and the association with the occurrence of combustion instability is clarified. According to the simulation results, the flame length varies greatly depending on the fuel conditions. When the flame length becomes sufficiently long, flame-vortex interactions occurred around the wall sections, which works as the main cause of combustion instability.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.9
• /
• pp.949-954
• /
• 2006

The purpose of this paper is to develop water jet plasma reactor and investigate the optimal condition of the syngas production by reforming of hydrocarbon fuel. Fuel used was propane and plasma was generated by arc discharge on water jet surface. Discharge slipping over the water surface has a number of advantages such as a source of short-wave and UV radiation, and it can be used for biological and chemical purification of water. Parametric screening studies were conducted, in which there were the variations of power ($0.18{\sim}0.74$ kW), water jet flow rate($38.4{\sim}65.6$ mL/min), electrode gap($5{\sim}15$ mm) and treatment time($2{\sim}20$ min). When the variations were 0.4 kW, 53.9 mL/min, 10 mm and 20 min respectively, result of maximum $H_2$ concentration was 61.6%, intermediates concentration were 6.1% and propane conversion rate was 99.8%.

• Analytical Science and Technology
• /
• v.9 no.1
• /
• pp.26-34
• /
• 1996

A method to determine the trace amount of Se and Bi in the scalp hair using the hydride generation inductively coupled plasma atomic emmission spectrometry was studied. The optimum operation conditions of ICP for hydride generation are 0.6~0.8L/min for the carrier gas flow rate, and 6mm above the induction coil for the observation height. Hydrochloric acid concentrations for the optimum hydride generation conditions were greater than 1.5M when 2.5% $NaBH_4$ and NaOH were used, and greater than 0.5M when 2.5% $NaBH_4$ and 0.1% NaOH were used. Severe interference effects are observed from transition metals such as Cu and Ni, and they could be circumvented by the coprecipitation with lanthanum hydroxide.

• Korean Chemical Engineering Research
• /
• v.53 no.4
• /
• pp.496-502
• /
• 2015

Hydrocarbon dew point(HCDP), a property which is the most generally used for describing natural gas condensation, is a very important parameter of natural gas quality specifications. HCDP is strongly influenced by the concentration of the heavier hydrocarbon components, especially $C_6+$, so, along with compliance with gas quality specifications, build up of procedures for obtaining accurate HCDP is essential for gas transmission company, because hydrocarbon condensation present may cause serious operational and safety problems. This study has been carried out in an attempt to measure HCDP accurately by the automatic hydrocarbon dew point meter under the actual field conditions. Measured HCDP also has been compared with calculated HCDP using the composition determined by gas chromatograph and industry accepted equation of state at multiple pressures, along with the cricondentherm. The test results are 1) the automatic hydrocarbon dew point meter was able to measure stable HCDP continuously 2) the automatic hydrocarbon dew point meter has been performed reference measurement by pure propane with a known dew point from literature, and 3) A meaningful differences was observed when comparing the automatic hydrocarbon dew point meter and gas chromatograph results for synthetic standard gas mixtures and real gas mixtures.

• Korean Chemical Engineering Research
• /
• v.49 no.5
• /
• pp.516-520
• /
• 2011

Sodium borohydride, $NaBH_4$, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). The hydrogen yield of sodium borohydride hydrolysis reaction was studied. The effect of temperature, $NaBH_4$ concentration, NaOH concentration and catalyst type on the hydrogen yield from $NaBH_4$ hydrolysis reaction were measured. The catalysts of Co-P/Cu, Co-B/Cu and Co-P-B/Cu were used in this study and there was no different effect of these catalysts on the hydrogen yield from $NaBH_4$. Under the temperature of $60^{\circ}C$, the hydrogen yield decreased as $NaBH_4$ concentration increased due to formation of gel with by-products and reactants. The gel formed during $NaBH_4$ hydrolysis reaction diminished the hydrogen evolution rate and total volume of hydrogen. Addition of NaOH stabilizer enhanced the formation of gel and then decreased the hydrogen yield.

• Korean Chemical Engineering Research
• /
• v.53 no.1
• /
• pp.11-15
• /
• 2015

Sodium borohydride, $NaBH_4$, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells(PEMFCs). Properties of $NaBH_4$ hydrolysis reaction using unsupported Co-B, Co-P-B catalyst were studied. BET surface area of catalyst, yield of hydrogen, effect of $NaBH_4$ concentration and durability of catalyst were measured. The BET surface area of unsupported Co-B catalyst was $75.7m^2/g$ and this value was 18 times higher than that of FeCrAlloy supported Co-B catalyst. The hydrogen yield of $NaBH_4$ hydrolysis reaction by unsupported catalysts using 20~25 wt% $NaBH_4$ solution was 97.6~98.5% in batch reactor. The hydrogen yield decrease to 95.3~97.0% as the concentration of $NaBH_4$ solution increase to 30 wt%. The loss of unsupported catalyst was less than that of FeCrAlloy supported catalyst during $NaBH_4$ hydrolysis reaction and the loss increased with increasing of $NaBH_4$ concentration. In continuous reactor, hydrogen yield of $NaBH_4$ hydrolysis was 90% using 1.2 g of unsupported Co-P-B catalyst with $3{\ell}/min$ hydrogen generation rate.

• KSBB Journal
• /
• v.18 no.2
• /
• pp.111-116
• /
• 2003

Hydrogen producing acidogenic microorganisms were self-immobilized using organic-inorganic hybrid polymer within 5 minutes. During the continuous tratment of synthetic wastewater at a hydraulic retention time of 20 hours, at 37$^{\circ}C$, pH 5.0, the self-immobillized granules were maintained in a stirred tank reactor. The black colored granules gradually became milky. Image analysis showed that the mean diameter of the milky colored granules ranged from 1.5 to 20. mm. The maximum bio-gas procuction rate was 380 ml/L/hy and the concentration of H$_2$was around 50%, while no methane was detected. Granular ECP was extracted and its content was measured to elucidate the role of the organic-inorganic hybrid polymer. Further increases of granule concentration are expected to increase the hydrogen production rate.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.4
• /
• pp.417-422
• /
• 2010

Low temperature diesel combustion was achieved via a combination of late injection timing ($8.5^{\circ}$ CA BTDC to $0.5^{\circ}$ CA BTDC) and heavy exhaust gas recirculation (37% to 48%) with ultra low sulfur Swedish diesel fuel in a 1.7L common rail direct injection diesel engine. When injection timing is retarded at a certain exhaust gas recirculation rate, the particulate matter and nitrogen oxides decease simultaneously, while the hydrocarbon and carbon monoxide increase. Hydrocarbon speciation by gas chromatography using a flame ionization detector reveals that the ratio of partially burned hydrocarbon, i.e., mainly alkenes increase as the injection timing is retarded and exhaust gas recirculation is increased. The two most abundant hydrocarbon species are ethene which is a representative species of partially burned hydrocarbons, and n-undecane, which is a representative species of unburned hydrocarbons. They may be used as surrogate hydrocarbon species for performing a bench flow reactor test for catalyst development.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 2010.04a
• /
• pp.188-188
• /
• 2010

수소 에너지는 화석연료의 한정된 매장량과 연소시 발생되는 환경문제를 해결하기 위해 가장 이상적인 대체에너지로서 주목을 받고 있다. 그러나 현재까지의 기술로는 경제성 있는 수소 제조가 쉽지 않다. 그 방법 중 바이오매스 및 유기성폐기물의 가스화를 통한 수소제조분야는 자원의 재순환, 페기물 처리, 열원의 이용, 직접적인 $CO_2$ 삭감 등의 부수적인 효과가 높아 경제성 있는 수소제조법으로 평가되고 있다. 이에 본 연구에서는 수소 생산을 목적으로 하는 가스화기와 초고온개질기로 구성된 Twin-Bed 가스화 시스템을 개발하고, 이를 이용한 Wood pellet(미송)의 가스화 특성 및 생성 가스의 초고온개질 특성을 고찰하는 것을 목적으로 한다. 가스화기의 시간변화에 따른 생성 가스 수율에 대한 결과, 생성 가스 수율은 약 20분경과 후 안정화되었으며, 실험 2시간 동안의 $H_2,\;CH_4,\;CO,\;CO_2$의 평균 수율은 각각 17.77, 11.94, 42.13, 28.16 Vol.%의 결과를 보였다. 가스화기로부터 생성된 가스는 down-draft 형태의 고온개질기로 도입시켜, $1100^{\circ}C$의 초고온에서 개질반응을 수행하였다. $CH_4$의 경우 11.95 Vol.%에서 0 Vol.%로 거의 대부분 분해되었으며, $H_2$는 17.77 Vol.%에서 25.46 Vol.%로 약 65.8% 증가하는 결과를 나타냈다. 또한 수소 생성량은 평균 5 L/min kg-Biomass이었다. 냉가스 효율은 72.1%로서 나타나, 일반적으로 폐기물의 냉가스 효율인 약 50% 전후의 결과에 비하여 높은 효율을 보였다.