• 전기의세계
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• v.41 no.4
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• pp.27-34
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• 1992

절연가스 봉입식 변압기는 변압기 TANK내에 절연 및 냉각매체로서 종래의 절연유 대신에 절연가스를 봉입한 것으로서 절연가스는 절연내력이 높을것, 열적으로 안정하고 불황성일것, 불연성일것, 인체에 무해할것, 열전달 특성이 우수할 것등의 성질이 요구되며 이와 같은 성질을 잘 만족시키는 SF6 가스가 사용되고 있다. 따라서 SF6 GAS 절연변압기는 고장으로 인해서 변압기는 고장으로 인해서 변압기 내부가 이상고온으로 되더라도 화재발생의 우려가 없고 주변의 환경에 피해를 주지 않으므로 시내나 건물의 지하등에 설치하는데 적절하다.

• Journal of the Korean Institute of Gas
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• v.16 no.2
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• pp.9-13
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• 2012

The present study has been carried out to diagnose the temperature safety of a boiler desuperheater which decreases abnormally higher temperature of superheated steam in a reheater of a power plant. The liquid water in the desuperheater stays in a closed space. It becomes heated by the high temperature superheated steam and boiling could occur. Boiling might increase internal pressure and it could destroy the desuperheater if the internal pressure exceeds the allowable pressure of the desuperheater. The present study modeled reasonably the desuperheater and four cases of heat transfer analysis are executed with the consideration of insulator and natural convective fluid flow of the inside cooling water. For the case excluded the natural convective fluid flow, the temperature exceeds the allowable temperature and pressure. On the other hand, for the real case included natural convective fluid flow and insulator, the active heat transfer from higher temperature region to lower temperature region occurs and it makes the temperature in the cooling water below the allowable temperature and pressure. From this fact, it could be thought that the desuperheater in the reheater is safe from destroy or back flow.

• Journal of Energy Engineering
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• v.4 no.2
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• pp.253-260
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• 1995

본 연구는 현재 아주대학교 구내에 건설중인 3T/D 석탄가스화 실증실험장치의 엔지니어링 설계자료 및 실험장치 각 부분의 사양을 종합화하여 최적의 설계조건을 도출하고 향후 스케일 업에 따른 장치변화 및 관련변수를 예측할 수 있는 공정모델을 개발하는데 그 목적이 있다. 모델은 3T/D 석탄가스화 장치와 같이 가스화기부분, 산화제 및 연료의 주입부분, 생성가스의 냉각부, 가스화기 예열부분 및 회분처리부로 구성된다. 개발된 모델에 의해 부분별 대체가능성을 평가하여 최적 조합형태를 제시하였고 결과의 타당성을 입증하기 위해 실제 플랜트의 설계자료와 프로그램에 의한 결과를 비교하였다. 또한 스케일 업 결과 변화폭이 가장 큰 부분은 냉각기의 길이가 냉각수 유입량 증대에 따라 급겨히 변화되어 냉각수 유입을 위한 냉각수 분산장치의 교체가 필요한 것으로 판단되었다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.11a
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• pp.22-30
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• 1993

증기분사 가스터빈 시스템의 성능예측 모델을 상용모사기인 ASPEN 코드를 이용하여 개발하였다. 압축기 및 터빈은 등엔트로피 과정으로, 연소기는 Thermal NOx 생성을 수반하는 연소모형으로서 가정하였다. 또한 터빈 냉각을 위한 추출공기량과 냉각공기가 터빈 성능에 미치는 영향은 적절한 상관 관계식을 도입하여 평가하였다. 본 예측 모델을 이용하여 예측된 결과와 실험결과간의 비교를 통하여 모델의 타당성을 제시하였고, 증기 분사량 및 터빈 냉각변수 변화에 따른 예측결과를 통하여 가스터빈 시스템 설계기준을 제시하였다.

• Journal of Energy Engineering
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• v.3 no.1
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• pp.28-35
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• 1994

가스터빈 사이클의 성능 및 NOx 배출물 생성량 예측을 위한 모사 프로그램을 개발하였다. 압축기 및 터빈은 등엔트로피 과정으로, 연소기는 Thermal NOx 생성을 수반하는 연소모형으로서 가정하였다. 또한 터빈 냉각을 위한 추출공기량과 냉각방식이 성능에 미치는 적절한 상관 관계식을 도입하여 평가하였다. 본 성능평가 모델을 이용하여 예측된 결과와 실험결과간의 비교를 통하여 모델의 타당성을 검증하였고, 증기 분사량, 터빈 냉각변수 및 압축비 변화에 따른 예측결과를 통하여 가스터빈 시스템 최적 운전 및 설계기준을 제시하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.135-140
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• 2007

An analysis has been conducted of the optimal condition to maximize the specific impulse for a liquid rocket engine with film cooling. The present engine performance has been compared with the published conceptual design to be verified satisfactorily accurate. The optimal combination of film coolant flow rate and the regenerative cooling capacity has been found for maximum specific impulse. The optimal fuel pump pressure increases and the optimal film coolant flow decreases for a larger thrust engine. Higher turbine inlet temperature increases both the fuel pump pressure and the film coolant flow rate as the optimal condition. The coking temperature has the same qualitative effect as the turbine inlet temperature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.291-298
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• 2010

A conventional EGR cooler, which is used in an EGR system of an automobile diesel engine, has a low heat-exchange efficiency. To maximize the heat transfer between the exhaust gas and coolant, dimples are formed on the surface of heat exchange tubes. When designing the dimpled EGR cooler, the net heat transfer areas in the conventional and dimpled tube-type EGR coolers are compared. Structural integrity evaluations are also performed by combining finite element analysis with a homogenization method. Subsequently, the process of manufacturing the dimpled tube, i.e., the formation of dimples, edge bending, center v-notch bending, compression, and plasma welding, is established and carried out. Thus, the dimpled EGR cooler is developed, and its performance is verified.

• Journal of the Korean Institute of Gas
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• v.8 no.4 s.25
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• pp.42-49
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• 2004

We study on and simulate the behavior of one-step fixed bed reactor which synthesize DiMethylEther(DME) from Methane. At last, we know that reaction is decreased in case of excess and no cooling because the temperature of reactor is decreased or increased seriously. Also, we study on optimizing the reactor so that we know the optimized operation condition according to cooling effect, space velocity of reactant and temperature of reactant, etc.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.66-72
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• 2003

The cooling mechanism for a liquid rocket engine of 10tf-thrust using kerosene as a fuel was studied from the viewpoint of both the regenerative and curtain cooling. Based on the concept of a highly-stratified gas flow in the combustion chamber, the cross section of the combustion chamber was spilt into 2 independent parts, core and exterior part. Additional fuel is injected into the exterior section and gas temperature can be reduced in the exterior section. Consequently, the heat flux into the coolant and wall temperature are reduced and the thermal stability of a liquid rocket en g i.ne could be improved.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.664-670
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• 2012

In this work, vibration characteristics of a flue gas cooler(FGC) for a heavy oil upgrading are experimentally analyzed and an effective method is proposed to reduce the vibration level. Firstly, the vibration under the operation condition of the FGC is measured and analyzed to identify the generation phenomena of vibration. And the displacement of the outer wall of the FGC is also analyzed to identify dominant frequencies of vibration. Secondly, an effective design to reduce the vibration is suggested by using the modal analysis. Consequently an improved design of the FGC gas cooler, which has lower vibration level, is obtained and then verified though the analysis and test.