• 동력기계공학회지
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• 제10권4호
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• pp.31-37
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• 2006

In this study, the ability for the function of double pipe inserted liquid pipe with small diameter in the gas pipe with large diameter for the circulating of liquid of high temperature and high pressure and low temperature and low pressure at the same time is presented. And in this double pipe, liquid pipe of high temperature and pressure is used to connect condenser and expansion valve and gas pipe of low temperature is used to connect evaporator and compressor. Also, when liquid refrigerant of high temperature and gas refrigerant of low temperature is circulated by reversed flow in the double pipe. The contribution of liquid gas heat exchange pipe is studied by comparison of the effect of heat transfer by temperature difference when liquid pipe and gas pipe is installed separately.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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• pp.702-708
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• 2006

This study shows the experimental characteristics of the double pipe inserted liquid pipe with small diameter in the gas pipe with large diameter for circulating of a liquid of high temperature, pressure and a gas of low temperature, pressure at the same time. So the functions of pipe and pipe's expansion and heat transfer are presented simultaneously. In the result, the temperature of gas refrigerant at the inlet of compressor increased about $5^{\circ}C$ by the heat transfer with liquid refrigerant in case of the double pipe. And liquid gas refrigerant which the temperature at the inlet of evaporator decreased about $3^{\circ}C$ comparing with the existing type flows into an evaporator COP of the double pipe increased about $7{\sim}10%$ comparing with that of the conventional pipe. And the noise of the double pipe at capillary tube is less than that of the conventional type about 3dB. Consequently. it is convinced the superiority of the double pipe in the heat loss and soundproofing aspect.

• 한국기계가공학회지
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• 제18권9호
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• pp.7-16
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• 2019

According to KGS FS551, the safety of an exposure pipe system should be calculated quantitatively by calculating the stress of exposed piping for thermal expansion. However, many pipe system designs and installation sites are not equipped for this. Therefore, KGS FS551 suggested the use of safe gas by presenting the recommended pipe shape. The shapes of various pipe systems have been derived. However, the recommended shape could not be an absolute evaluation standard. Furthermore, the ongoing debate over standards between a plumbing installer and an inspector is an obstacle to the efficient and safe use of gas. Therefore, the correct pipe system evaluation method is examined in this study, and the safety of the existing exposed pipe system is verified.

• Journal of Advanced Marine Engineering and Technology
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• 제8권1호
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• pp.4-16
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• 1984

The heat-pipe is characterised by the highly effective thermal conductance. In order to change the thermal conductance, the heat-pipe is connected to a reservior having a space which is filled with non-condensable gas. In normal operation, the vapour of working fluid will tend to pump the non- condensable gas into the reservoir and the gas-vapour interface situates at some point along the condenser section. The thermal conductance is affected by non- condensable gas. It is concluded that the suitable position of interface can be used to control the temperature of condenser section. In this experiment, the evaporating part is connected to the lowest position of heat-pipe. The copper heat-pipe which is filled with Freon-113 or distilled water as working fluid utilized. As results of experimental study, thermal conductance can be increased by the operating pressure which is infulenced by non-condensable gas. A correlative equation between the thermal conductance and the mass of non- condensable gas is also obtained.

• 한국소음진동공학회논문집
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• 제18권8호
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• pp.797-804
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• 2008

In the gas supply pipe, the gas leakage caused by the impact of the construct equipment is serious problem. The identification of the impact position is an important issue and an engineering work. For the basic research of this problem, the principle studies for the acoustic wave propagation in a gas pipe are proceeded in this paper. This principal work is based on the identification of the cut-off frequency associated with major modes of the gas pipe theoretically and experimentally The cut-off frequency is confirmed by STFT and cross-correlation function is used to identify the leakage position.

• 한국가시화정보학회지
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• 제22권1호
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• pp.68-78
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• 2024

The stratification phenomena of still hydrogen (20%) and methane (80%) gas mixture in a vertical urban gas pipe have been investigated by simulating the flows based on a mixture model. The stratification is accompanied with the natural convection by the buoyancy force. The hydrogen volume fraction in the upper sections of the pipe increases with time but the increasing rate gets smaller due to the weaker buoyancy force. The pipe with a smaller diameter exhibits a higher peak of hydrogen concentration. The size of vortices is proportional to the pipe diameter. The slip velocity between hydrogen and methane oscillates with a large amplitude at the earlier stage of stratification and then the amplitude decreases sharply. The slip velocity decreases with the diameter, making the stratification become slower. The length of pipe does not affect the stratification since the pipe is sufficiently long relative to the size of vortices.

• 한국가스학회지
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• 제22권5호
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• pp.62-71
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• 2018

2017년 한국가스안전공사 가스안전연구원의 자체 조사에 따르면, 국내 고압가스배관 중 매설된 배관의 길이는 대략 770km이며, 그 중 84%가 울산과 여수산업단지에 몰려 있다. 특히 20년 이상의 장기 운영 배관이 56%에 달하며, 이는 매설된 고압가스배관의 관리가 시급하다는 것을 시사하고 있다. 매설된 가스배관의 주요 사고 원인으로 미국 PHMSA, 유럽의 EGIG 등에서는 타공사와 외면부식을 지적하고 있으며, 배관 벽두께의 손실에 의한 누출 및 파열 등의 사고로 보고된다. 따라서 배관에 결함이 발생하였을 때, 그 결함이 배관의 잔존수명에 영향을 미치는 바를 평가하는 것이 중요하다. DNV나 ASME 등에서는 배관에 인위결함을 만든 후 수압 파열 실험을 통하여 배관의 잔존강도를 평가했다. 배관의 잔존강도를 운전압력과 연관시키면, 배관이 파열되는 시점의 벽 두께가 계산되며 해당 배관의 부식 성장률만 정확히 알 수 있다면, 배관의 잔존수명을 예측할 수 있다. 본 연구에서는 기존에 결함깊이가 벽두께의 80% 이하에서 적용된 수식을 개선하기 위하여 국내 매설배관의 80%를 차지하는 A53 Grade.B와 A106 Grade.B 배관에 대하여 결함 깊이가 80~90%의 범위에서 실험하였고, 결함과 잔존강도 관계를 표현한 수식을 만들었다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.551-554
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• 2006

Inhibition of propellant temperature rising in liquid propulsion rocket using cryogenic fluid as a propellant is very important. Especially propellant temperature rising during stand-by after filling and pre-pressurization can bring into cavitation in turbo-pump. One of the method preventing propellant temperature rising in cryogenic feeding system is recirculating propellant through the loop composed of propellant tank, feed pipe, and recirculation pipe. The circulation of propellant is promoted through gas-lift effect by gas injection to lower position of recirculation pipe. In this experiment liquid oxygen and gas helium is used as propellant and injection gas. Under atmospheric and pressurized tank ullage condition, helium injection flow-rate is varied to observe the variation of recirculating flow-rate and propellant temperature in the feed pipe. There is appropriate helium injection flow-rate for gas-lift recirculation system.

• 화약ㆍ발파
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• 제31권2호
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• pp.25-31
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• 2013

본 시공사례는 "성남~여주 복선전철 제 O공구 노반건설공사"중 도로 하부통과 구간으로서 터널의 노선을 따라 진동 및 소음으로 인한 피해 영향권 내에 아파트, 도자기 생산공장 및 국도 등 주요 보안물건 등이 위치하고 있다. 특히, 터널 노선 12m 상부의 국도를 따라 도시가스관(${\varphi}500mm$)이 매설되어 있어, 진동허용기준(1.0cm/sec) 이하로 안전하게 굴착하기 위하여 전자발파 공법을 적용하였으며, 굴착에 따른 지반의 변위를 최대한 방지하기 위하여 정밀 진동제어와 함께 신속한 굴착 및 보강이 이루어짐으로서 안전하게 완료되었다.

• 한국가스학회지
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• 제11권2호통권35호
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• pp.1-4
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• 2007

가스는 산지에 따라 그 조성이 다르며, 이러한 가스조성의 변화는 가스 배관망 내 발생하는 압력손실 값에 영향을 미치므로 매우 중요한 고려 요소이다. 그러므로 평균 가스조성(비중) 대신 각 인입지점으로 인입되는 가스가 실제로 가지고 있는 가스조성을 사용하는 것이 배관망 해석 수행 시 더욱 정확한 결과를 얻을 수 있다. 본 연구에서는 가스 배관망에서 인입지점으로 인입되는 가스 조성을 평균값이 아닌 실제 조성을 사용할 경우 소비자에게 가스를 공급하는 공급지점의 공급압력에 미치는 영향을 분석하였다. 본 연구결과를 비교하기 위하여 각 인입지점의 가스조성을 평균하여 모든 인입지점의 가스조성으로 동일하게 사용하여 산출된 압력 값을 사용하였다. 그 결과, 실제 가스조성 고려 시 공급압력에 미치는 영향은 상당한 수준이므로 천연가스 산업현장의 공급 배관망에 대한 배관망해석 수행 시 실제의 가스조성을 반드시 고려하여야 정확한 분석결과를 얻을 수 있음을 알 수 있었다.