• 한국추진공학회지
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• 제24권6호
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• pp.120-125
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• 2020

한국형발사체 액체로켓엔진의 개발을 위해 나로우주센터에 구축/개발된 엔진 연소 시험설비에서 75톤급 액체 로켓엔진의 연소시험을 수행하였다. 연료온도 271 K 의 탈설계점 연소시험 중 터보펌프 연료입구압력 저하가 발생하여 시험을 중지하였다. 연료의 수분함유량분석, 연료 런탱크 냉각설비를 이용한 냉각시험, 탈수시험을 수행한 결과 해당 현상이 발생한 원인이 연료 내 수분이었다고 결론을 내렸다. 향후 본 논문의 연구에서 도출된 결과를 적용하여 케로신 연료의 수분관리를 하여 액체 로켓엔진 개발시험을 수행할 예정이다.

• 한국입자에어로졸학회지
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• 제5권2호
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• pp.37-43
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• 2009

Particulate matter (PM) is one of the major indoor air pollutants especially in the subway station in Korea. In order to remove PM in the subway station, several kinds of PM removal system such as roll-filter, auto-washable air filter, demister, and electrostatic precipitator are used in the air handling unit (AHU) of subway stations. However, those systems are prone to operation and maintenance problems since the filter-regeneration unit consisting of electrical or water jet parts might malfunction due to the high load of particulates unless the filter medium is periodically replaced. In this study, the use of axial-flow cyclone was proposed for particulate filter unit in the AHU for its low operation and maintenance cost. Novel shape of axial-flow cyclone was designed by using computational fluid dynamics (CFD). The shape of vortex vane was optimized in terms of pressure drop and tangential velocity. In addition, CFD analysis was validated experimentally through the pressure drop measurement of mock-up model. We found that pressure drop and tangential velocity of fluid through the axia-flow cyclone was significantly affected by the rotating degree of vortex vane and the numerical prediction of pressure drop agreed well with experimental measurement.

• 한국가스학회지
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• 제28권2호
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• pp.47-55
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• 2024

한국에는 2030년까지 100여 기의 액화수소 탱크가 도입될 것으로 전망된다. 액화수소는 -253 ℃ 상태로 진공단열구조 탱크에 저장되기 때문에 단열에 문제가 생기면 탱크가 파열되는 대재해의 가능성이 상존한다. 그래서 법령에서는 최후의 보루로 PRV를 설치하도록 규정하고 있다. 주의할 것은 액화수소의 경우 배관의 압력강하를 무시하고 용량을 잘못 계산하면 무용지물이 된다는 것이다. CGA S-1.3에서는 PRV 입·출구 압력강하율을 각각 3% 미만 및 10% 미만으로 하도록 하고 있다. 그러나 배관의 압력강하량과 유량 사이에 상호 의존성이 있어 이들 값을 단번에 계산하는 것이 불가능하다. 그래서 본 연구에서는 매트랩/시뮬링크를 이용하여 PRV시스템의 압력강하율을 계산하는 시뮬레이터를 개발하고, 설계 요소에 대한 압력강하율의 민감도를 평가하였다.

• 한국산업융합학회 논문집
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• 제25권4_2호
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• pp.541-547
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• 2022

Before making a prototype, we predicted the inlet/outlet differential pressure and flow coefficient, which are the most basic design data for the valve through the design and numerical analysis of the trim, which is the most important in the localization development of the 1500Ib high differential pressure control valve used for boiler feed water. As a result, the design value and the analysis value were found to be about 98% similar. The flow field within the fluid velocity of 23m/s to prevent cavitation was also found. The result of the numerical analysis on thermal stress due to the characteristics of valves exposed to high temperatures showed that it was found to be about 18% less than the allowable stress of the bolt fixing the trim. When all loads such as pressure, self-weight, and vibration are applied, however, it is judged to go beyond the currently calculated thermal stress, exceeding the allowable stress.

• 동력기계공학회지
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• 제13권2호
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• pp.30-35
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• 2009

Numerical Calculations for dimensionless pressure drop (friction factor times Reynolds number) have been obtained for fully developed laminar flow of MPL(Modified Power Law) fluid in isosceles triangle pipes. The solutions are valid for Pseudoplastic fluids over a wide range from Newtonian behavior at low shear rates through transition region to power law behavior at higher shear rates. The analysis identified a dimensionless shear rate parameter which for a given set of operating conditions specifies where in the shear rate range a particular system is operating, i.e., Newtonian, transition or power law region. The numerical calculation data of the dimensionless pressure drop for the Newtonian and power law regions are compared with previously published asymptotic results presenting within 0.16 % in Newtonian region and 2.98 % in power law region.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.143-147
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• 2008

Numerical analysis is performed to find flow and heat transfer characteristics for ring type heat exchanger. 3-D numerical predictions are carried out for the ring type heat exchanger system with Reynolds number varying in the range of 1,000 and 10,000. From the prediction, streamwise velocity, pressure drop, flow rate and heat transfer coefficient are analyzed. It is also found that characteristics of pressure drop and heat transfer generally follow well proportional variations of Re$m^$for the wide range of Reynolds number considered in this study.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1166-1171
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• 2009

Fin-tube heat exchangers are widely used in refrigeration systems. To improve the performance of fin-tube heat exchangers, the shape of plain fin was developed in slit fin and louver fin. These pins have higher heat transfer performance as well as larger pressure drop. Recent studies of a delta winglet vortex generators(DWVG) show less heat transfer capacity than louver fin. However, the DWVG have very small pressure drop. This paper compares the performance for the plain fin and DWVG fin in terms of flow characteristics and heat transfer based on CFD analyses. The DWVG generate vortex and delayed flow separation and leads to a reduction of a wake region behind a tube. The results show that the DWVG produce improved heat transfer and reduced pressure drop compared to a plain fin. This result is opposite to the Reynolds analogy.

• 설비공학논문집
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• 제21권6호
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• pp.340-346
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• 2009

This paper numerically investigates thermo-flow characteristics of offset strip fins to obtain a correlation between heat transfer and pressure drop. The flow was divided into three regimes, i.e. laminar, transition and turbulent. The predicted j and f values from the SST k-$\omega$ turbulence model agreed with previous correlations with the error less than 20% in transition and turbulent regimes. Heat transfer and pressure drop were predicted by varying Prandtl number from 0.5 to 40. The Prandtl number showed little effects on pressure drop but had great effect on the heat transfer characteristics. An overall correlation to predict j was suggested by incorporating the effect of Pr and a new j correlation was suggested for each Pr.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.233-238
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• 2008

This paper numerically investigates thermo-flow characteristics of offset strip fins to obtain a correlation between heat transfer and pressure drop. The flow was divided into three regimes, i.e. laminar, transition and turbulent. The predicted j and f values from the SST k-$\omega$ turbulence model agreed with previous correlations with the error less than 20% in transition and turbulent regimes. Heat transfer and pressure drop were predicted by varying Prandtl number from 0.5 to 40. The Prandtl number showed little effects on pressure drop but had great effect on the heat transfer characteristics. An overall correlation to predict j was suggested by incorporating the effect of Pr and a new j correlation was suggested for each Pr.

• KSBB Journal
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• 제10권5호
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• pp.482-490
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• 1995

The relationship between pressure drop and liquid flow rate, for an axial and a radial flow chromatographic column packed with compressible porous media was theoretically analyzed using modified Kozeny-Carman equation. The results were compared with experimental observations obtained using compressible DEAE-agarose as a model medium. At 2-9 psi range studied, the theoretical derivation accounting for 'gel compression' effect predicted simple Langmuirian type response of volumetric flow rate to changes in pressure drop. On the other hand, the experimental response was more or less sigmoidal. At the same pressure drop, radial column showed 2-3 times higher flow rates than those of axial column both theoretically and experimentally. Using r-HBsAg crude extract, protein resolution effects between the two types of columns at different flow rates were compared side-by-side. It turned out that, though general chromatographic behavior was very similar, axial column was somewhat superior in terms of r-HBsAg recovery yield and specificity. However, the number of theoretical plates analysis indicated the protein resolution effects were comparable.