• 한국산학기술학회논문지
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• 제16권6호
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• pp.3708-3713
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• 2015

본 연구의 목적은 연료전지 자동차의 스택 시스템의 열적 특성을 파악하기 위하여 상용 수치 해석 프로그램을 이용하여 열전달 성능을 해석적으로 고찰하였다. 이를 위하여 연료전지 자동차가 일반도로 및 등판도로 등 주행 특성에 따른 스택 열관리 시스템의 냉각 특성과 에어컨의 작동 여부 등 운전 특성에 따른 스택 열관리 시스템의 냉각 특성을 고찰하였다. 스택 라디에이터로 유입되는 공기 유속이 증가함에 따라 모든 냉각수 유량조건에서 열전달 성능은 향상되었다. 공기 유속이 2 m/s에서 10 m/s로 증가함에 따라 스택 라디에이터의 열전달 성능은 냉각수 유량 20 l/min에서 105.3% 증가하였고, 냉각수 유량 120 l/min에서 221.3% 증가하였다. 스택 라디에이터는 가혹조건인 등판 각도 8% 및 속도 50 km/h에서 냉각수 입구 온도차 $9.45^{\circ}C$로 일반조건인 등판 각도 0% 및 속도 120 km/h에서 냉각수 입구 온도차인 $5.1^{\circ}C$보다 85.3% 증가했다. 또한, 연료전지 자동차가 가혹조건인 등판 주행시 에어컨 시스템을 작동할 경우 스택의 안정적 작동을 허용하는 한계 온도인 $70^{\circ}C$를 초과할 수 있다.

• 한국초전도ㆍ저온공학회논문지
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• 제17권1호
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• pp.21-24
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• 2015

New results of dependence of magnetic field, trapped by a stack of HTS tapes, on amount of tapes in a stack are reported. Commercial GdBCO tape 12 mm width and without Cu layer was used for the research. Tape was divided in square pieces $12{\times}12mm^2$ from which stacks were formed. Filling factor of the tape was about 1.4%. Measurements were carried out for stacks with height from 5 to 250 pieces and at wide temperature range from liquid helium to liquid nitrogen. Both FC (field cooling) and ZFC (zero field cooling) cooling methods were used in the research. These two methods show matching results with good accuracy. As a result dependences of trapped magnetic flux on amount of tapes for different temperatures were received. Research shows, that with increasing height of the stack trapped magnetic field value reach saturation at about 60 tapes in a stack for low temperatures. From 60 to 100 tapes increase of magnet flux is only 5%. Thus increase amount of tapes in a stack is not profitable. Also investigation of trapped magnet field relaxation was carried out. Relaxation speed decreases with increasing amount of elements. It means that the higher the stack is, the longer trapped flux will be held in cause of the same temperature.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1059-1064
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• 2008

The present study is to reduce the thermal phenomena and stack effect of nude elevator of the high-rise building used CFD simulation. Since many High-rise buildings used the curtain-wall glass, thermal phenomena and stack effect can easily occur at hot and cold season, respectively. The simulation has been conducted and verified for the effects of the amount of suppling air to the environment of the inside nude elevator shaft. The results of simulations show that the problems due to the thermal and stack effect will be reduced by enforced ventilation or natural ventilation and those will be presented by temperature and velocity profiles and pressure differences.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.471-476
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• 2006

Thermoacoustic refrigerators are operated with acoustic power to pump heat. The acoustic standing wave displaces the gas In the channels of the stack while compressing and expanding. The thermal interaction between the osillating gas he surface of the stack generates an acoustic heat pumping. in this study, a thermoacoustic refrigerator is composed of a resonator of 4cm diameter, stack of plates, heat exchangers and cooling part. Length of the hot heat exchangers, the stack of plates and the cold heat exchanger are 9mm, 8mm and 6mm respectively. Using helium as a coolant at frequency of 516Hz, the cold-part temperature of exchanger fell to $-19.0^{\circ}C$ after 1hours.

• 설비공학논문집
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• 제7권3호
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• pp.473-487
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• 1995

A loud speaker-driven zero-c.o.p. thermoacoustic refrigerator where an automotive catalytic converter is utilized as a stack has been fabricated and investigated experimentally. Without any heat exchangers at both ends of stack(and thus with zero c. o. p.), temperatures on the stack are measured and various heat transfer rates are calculated from the measured temperatures. Temperatures on the stack have been also calculated numerically using a finite difference method. The measured temperatures are in fair agreement with the calculated temperatures for lower frequency than 300Hz, however, the former deviates from the latter considerably for higher frequency. Two types of c. o. p. have been defined as appropriate to the experiment. While the nominal c. o. p. is zero(the condition in which the pumped heat flow rate in the pore exactly cancels the axial heat conduction down the stack), the true c. o. p. is found to be about 0.14 for 300Hz from the experiments.

• 한국재료학회지
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• 제30권5호
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• pp.262-266
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• 2020

In this paper, we investigated the effect of the passivation stack with Al₂O₃, hydrogenated silicon nitride (SiN_x:H) stack and Al₂O₃, silicon oxynitride (SiON_x) stack in the n type bifacial solar cell on monocrystalline silicon. SiNx:H and SiON_x films were deposited by plasma enhanced chemical vapor deposition on the Al₂O₃ thin film deposited by thermal atomic layer deposition. We focus on passivation properties of the two stack structure after laser ablation process in order to improve bifaciality of the cell. Our results showed SiN_x:H with Al₂O₃ stack is 10 mV higher in implied open circuit voltage and 60 ㎲ higher in minority carrier lifetime than SiON_x with Al₂O₃ stack at Ni silicide formation temperature for 1.8% open area ratio. This can be explained by hydrogen passivation at the Al₂O₃/Si interface and Al₂O₃ layer of laser damaged area during annealing.

• 한국환경보건학회지
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• 제30권5호
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• pp.378-387
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• 2004

This study was carried to investigate the emission characteristics of mercury from domestic and industrial MSW (municipal solid waste) incinerator stacks. The mercury concentration levels of flue gas from 32 MSW incinerators stacks selected were above the criteria level ($5{\mu}g/S\;m^3$). MSWI facilities exceeding the criteria levels in Korea are due to the poor units comparison of combustion chamber(CC)-cyclone(CY)-stack. So, the mercury from MSW incinerators stack were suspected to contaminate the natural system unless the MSW incinerators were properly controlled. Mean-while, the relationship between mercury concentration and temperature of flue gas in MSW incinerator stacks were examined at two temperature ranges (Group A : $29.85{\sim}327.63^{\circ}C$, Group B : $446.9{\sim}848.15^{\circ}C$). The mercury concentration in flue gas with high temperature range was higher than that of flue gas with low temperature rage. This mean that the temperature of flue gas plays an important role in mercury control in MSW incinerator. The emission characteristics oi mercury was also evaluated by using the correlation matrix between the mercury and NOx, $PM_{10}$, moisture (MO.) at both low temperature and high temperature flue gas ranges. The mercury concentration was mainly affected by NOx, $PM_{10}$. moisture (MO.) at low temperature range, while the mercury concentration at high temperature flue gas was mainly affected by NOx, moisture (MO.). From these results, it was suggested that the temperature of cooling system and the air pollution control device should be properly regulated in order to control mercury of flue gas in MSWI incinerator.

• 한국환경과학회지
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• 제9권1호
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• pp.57-64
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• 2000

The sensitivity analysis of two short-term models (ISCST3, INPUFF2.5) is performed to improve the model accuracy. It appears that the sensitivities on the changes of wind speed, stack height and stack inner diameter in the near distance from source, stability and mixing height in the remote distance form source, are significant. Also the gas exit velocity, stack inner diameter, gas temperature and air temperature which affect the plume rise have some effects on the concentration values of each model within the downwind distance where final plume rise is determined. And in modeling for the atmospheric dispersion of point pollutant source INPUFF2.5 can calculate amount, trajectory of puff and concentration versus time at each receptors. So, it is compatible to analyze distribution of point pollutants concentration at modeling area.

• 설비공학논문집
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• 제6권2호
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• pp.120-129
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• 1994

A numerical investigation has been carried out for the electrochemical reaction, mass and heat transfer characteristics of the Molten Carbonate Fuel Cell(MCFC) stack. The effects of cooling air channel and water gas shift reaction were taken into account. The current density distribution of electrodes, the molecular fractions of reactant gasses and three dimensional temperature distribution can be calculated and shown by several lines of equivalent values. The results have been compared with the existing ones, and reasonable agreement has been obtained. To examine the influence of changing parameters, such as the composition of reactant gases, the target average current density, the utilization of reactant gases, the cooling air inlet temperature and flow rates, the computer simulation has been done. The analysis method and computer program developed in this study will be greatly helpful to design and verify the optimum operating condition of MCFC stack.

• 한국가스학회지
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• 제21권6호
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• pp.81-87
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• 2017

SOFC(Solid Oxide Fuel Cell)는 고온 연료전지 중 하나이며, SOFC 시스템과 스택은 고온 운전 특성을 가지고 있다. 이러한 특성 때문에 시스템 설계 및 재료의 선택, 내구성 확보, 안전성능 확보에 많은 어려움을 가지고 있다. 따라서 SOFC 연료전지의 상용화와 보급을 위해서는 안전성능 평가기술과 평가시스템의 개발이 병행되어야 한다. 본 연구에서는 스택 안전성능 평가시스템의 제작을 위하여 국내 외 SOFC 관련규격 및 스택의 위험요소를 분석하였다. 분석한 자료를 바탕으로 스택 안전성능 평가 시스템의 제작을 위한 평가항목을 도출하였다. 본 연구 결과를 통해 SOFC 연료전지의 보급 활성화와 안전한 사용 환경에 기여할 수 있기를 기대한다.