• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.837-845
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• 2013

An airlift pump can be used to pump liquids and sediments within itself, which cannot easily be pumped up by a conventional method, by using the airlift effect. This characteristic of the airlift pump can be exploited in a DCFC (Direct Carbon Fuel Cell) so that molten fuel with high temperature may be carried or transported. The basic characteristics of airlift are investigated. A simple system is constructed, where the reservoir is filled with water, a tube is inserted, and air is supplied from the bottom of the tube. Then, water is lifted and its flow rate is measured. Bubble patterns in the tube are observed in a range of air flow rates with the parameters of the tube diameter and submergence ratio, leading to four distinct regimes. The pumping performance is predicted, and the correlation between the supplied gas flow rate and the induced flow rate of water is found.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1158-1159
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• 2008

본 논문에서는 상온상태에서 2W급 직접 메탄올 연료전지 모듈을 구동하여 연료전지 모듈의 성능 특성을 분석하고자 한다. 상온상태에서 연료극으로 공급하는 메탄올의 농도와 유량을 변화를 시켜 상온에서 최적의 메탄올 농도와 유량을 찾고 공기극에 공기를 공급 하였을 때 와 공기를 공급하지 않았을 때 의 연료전지의 출력을 전자 부하기를 이용하여 부하를 주고 메탄올의 유량을 변화 시켜가면서 비교해보았다.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.42-44
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• 2008

연료전지가 동작할 때에는 공기공급을 위한 압축기가 동작하게 되는데 공기의 유량에 따라 연료전지의 출력전력이 달라진다. 또한 공기의 유량에 따라 압축기에서 소비하는 전력이 달라지기 때문에 공기 유량에 따른 연료전지의 최대 효율점이 존재하게 된다. 본 논문에서는 연료전지의 출력전력에서 압축기의 손실전력을 제외한 순수 파워를 최대로 낼 수 있는 유량을 추적 제어하는 알고리즘을 제안한다.

• Nuclear Engineering and Technology
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• v.10 no.2
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• pp.79-86
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• 1978

The object of this study was to obtain data on air-distributions in two-phase up flow in vertical rod-bundle test-section. The test-section in this study was a hexagonal shaped 61-rod bundle where each rod was wrapped with helical spacers. The variables were flow rates of air and water and air inlet positions. Experimental data were obtained at the outlet of the test-section. The experiments were performed in two parts. Firstly, data were taken at increasing flow rates of air keeping water flow rates constant, and secondly, at simultaneous increase of air and water flow rates. At each flow condition, air supply position could be changed to 4 different positions. Data obtained by electrical void-needle technique were analyed and are presented here in graphical forms for comparison. The results of this study demonstrate qualitatively that air-distribution tends to be more uniform as water flow rates are increased. The air supply positions have noticeable effects on the pattern of air-distribution.

• Journal of the KSME
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• v.49 no.12
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• pp.39-43
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• 2009

이 글에서는 소재의 재활용성과 제품의 실용성이 향상된 대유량 공기압 소음기의 국산화 개발 과정과 함께 수행된 가속 내구시험에 대한 내용을 간략히 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.8
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• pp.503-510
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• 2016

Incinerators generally emit pollutants such as NOx and CO during the combustion process. In this paper, pollutant emissions and temperature distributions were studied in a simulated incinerator with a reversed (relative to the flue gas flow) secondary air injection system. The experiments were performed by using a lab-scale furnace in order to evaluate the effects of the injection location, direction and flow rate of secondary air jets. The emission of NOx was lower in the case of reversed secondary air injection than in the case of cross injection, due to the recirculation and mixing of the exhaust gas. In the reversed air injection cases, thermal NOx emissions decreased as secondary air ratio increased from 30 to 60 and slightly increased at secondary air ratios higher than 60. In most cases, CO emissions were not detected except for a few reversed secondary air injection cases, in which cases CO concentrations below 2ppm were observed.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.513-518
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• 1996

저농도 방사성 액체폐기물의 최종 처리를 목적으로 본 연구에서는 면 35%와 Polyester 65%가 함유된 합성섬유를 증발매체로 하여 자연상태의 공기를 강제 송풍시키는 자연증발처리시설에서 증발에 영향을 미치는 주요 변수에 따라 증발 단위 면적당 Cs-137, Co-60을 함유한 방사성 폐액의 증발량측정 및 제염계수를 조사하였다. 증발효과는 유입공기의 습도가 낮고, 공기의 유속과 공급액의 유량이 증가하고 유입공기 및 폐액의 온도가 높아질수록 증발량이 증가하였다. 실험결과 유입된 공기는 1$0^{\circ}C$ 이상, 습도는 80% 이하, 공급폐액의 유량이 3.4 $\ell$/hr $m^2$ 이상, 공기유속은 1.14~l.47 m/sec 범위가 조업조건이며 이때 제염계수는 5.1 $\times$ $10^3$, 배출공기의 방사능 농도는 4.7$\times$$10^{-13}$ $\mu$Ci/$m\ell$ air로 측정되었다. 공급유량이 4.6$\ell$/hr.$m^2$와 공기유속이 1.47 m,/sec일때 최대 증발조건으로 나타났으며, 이때 증발량은 총 증발면적 11,250$m^2$ 에서 1.2 ㎥/hr로 측정되었으며 대기의 온.습도 및 풍속에 따른 실험을 통하여 달톤형 증발식의 Wind Factor ［Eh ＝ (0.0168 ＋ 0.0141V)$\Delta$H］를 도출하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.23-26
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• 2007

A preliminary， study of low temperature condition was performed to simulate high altitude condition. The mixed air temperature were investigated at various condition by experiments using cryogenic air by heat exchanger and normal temperature air. An experimental setup was constructed to simulate low temperature condition with liquid nitrogen. To control mass flow rate, orifice and pressure regulators were used. The experimental results show that the mixed air temperature increases linearly with mass flow rate of normal temperature air. Therefore it can be help to simulate a low temperature condition of high altitude.

• Journal of the Korean Institute of Gas
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• v.11 no.1 s.34
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• pp.1-8
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• 2007

The purpose of this study is to conduct a survey of the flame stability range and the emission characteristics for the optimum design of turbulent premixed flat burner. For that, the flame stability range was selected by the direct photography of the flame. And the mean temperature and CO, HC, $CO_{2}\;and\;O_{2}$ concentration distributions by changing the excess air ratio were measured. As results of this study, the flame stability range turned out to be getting narrower as fuel flow was increased. The blue flame mode was more excellent than any other flame modes in the emission characteristics by excess air ratio change. And the emission characteristics by fuel flow change were best at fuel flow 1l/min. Also, we found combustion noise during experiment of flame stability range. It had nothing do with excess air ratio range.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.61-69
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• 2015

The objective of this study is to experimentally investigate the mixed flow behaviors and oxygen transfer characteristics of a vertical orifice ejector. The experimental apparatus consisted of an electric motor-pump, an orifice ejector, a circulation water tank, an air compressor, a high speed camera unit and control or measurement accessories. The mass ratio was calculated using the measured primary flow rate and suction air flow rate with experimental parameters. The visualization images of vertically injected mixed jet issuing from the orifice ejector were qualitatively analyzed. The volumetric oxygen transfer coefficient was calculated using the measured dissolved oxygen concentration. At a constant primary flow rate, the mass ratio and oxygen transfer coefficient increase with the air pressure of compressor. At a constant air pressure of the compressor, the mass ratio decreases and the oxygen transfer coefficient increases as the primary flow rate increases. The residence time and dispersion of fine air bubbles and the penetration of mixed flow were found to be important parameters for the oxygen transfer rate owing to the contact area and time of two phases.