• Journal of Advanced Marine Engineering and Technology
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• 제21권4호
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• pp.421-429
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• 1997

This study is theoretically examined the influences on the performance of diesel engine super¬charged by exhaust gas turbine with the change of excess air factor, admission ratio, total efficien¬cy of turbine and compressor, scavenging pressure ratio, and scavenging temperature. In this study, all calculations are carried out by computer, and the theoretical engine performance is com¬pared with the actual engine performance which is offered from engine manufacturer. Following results are acquired by this study. The mean effective pressure is increased with decrease of excess air factor or increase of scavenging pressure ratio. As the admission ratio or total efficiency of tur¬bine is increased, the mean effective pressure is increased but the specific fuel consumption is decreased. Mean calculation error compared with the actual engine performance is under 5 per¬cents, therefore, this calculation method can be used in the design of diesel engine.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.236-246
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• 2003

This paper focuses on developing a model of a PEM fuel cell stack and to integrate it with realistic model of the air supply system for fuel cell vehicle application. The fuel cell system model is realistically and accurately simulated air supply operation and its effect on the system power and efficiency using simulation tool Matlab/Simulink. The Peak performance found at a pressure ratio of 3, and it give a 15mV increase per cell. The limit imposed is a minimum SR(Stoichiometric Ratio) of 2 at low fuel cell load and 2.5 at high fuel cell load.

• 대한기계학회논문집B
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• 제39권9호
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• pp.713-718
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• 2015

본 연구의 목적은 자동차용 에어컨 시스템의 연비 개선을 위하여 압축기의 성능 향상을 도모하고자 하는데 있다. 압축기 성능은 자동차용 에어컨 압축기 전용 열량계를 이용하여 평가를 수행하였다. 압축기의 성능을 향상시키기 위하여 흡입 유량의 증대와 토출 사체적 축소를 검토하였으며, 각 개선 항목에 대한 평가를 진행하여 성능과 COP 의 개선을 확인하였다. 흡입 유량을 증대했을 경우 저속 구간보다 고속구간에서의 성능 효과가 컸으며, 토출 사체적을 축소했을 경우 상대적으로 저속 구간의 성능 개선효과가 컸다. 조합품의 경우 저속과 고속에서 전반적으로 균형 있게 개선되었으며, 토출측 온도가 가장 크게 개선되었다. 성능의 경우 저속에서 약 3.2%, 고속에서 약 8.3% 개선되었으며, COP 는 저속에서 약 5.8%, 고속에서 약 6.2% 개선되었고, 토출 온도는 저속에서 $3^{\circ}C$, 고속에서 $5^{\circ}C$ 개선되었다.

• 해양환경안전학회지
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• 제23권4호
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• pp.393-399
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• 2017

왕복동식 압축기에서 피스톤과 커넥팅로드는 중요한 부분이다. 이러한 주요부에 기계적 부하가 과도하게 가해지면 해당 기부속이 손상될 수 있으며, 교체하기도 쉽지 않고 비용도 많이 든다. 따라서 내구성과 수명에 영향을 미치는 요인을 분석할 필요가 있다. 본 연구의 주요 목적은 피스톤과 커넥팅로드의 최대 응력 집중 위치를 확인하는 것이다. 이를 위해 설계된 공기압축기의 작업 공정의 동적계산을 기반으로 피스톤 및 커넥팅로드의 응력 분석을 수행하였다. 공기압축기의 피스톤과 커넥팅로드의 3 차원 모델을 따로 설계하고, 이러한 부품들의 유한요소 해석은 수치해석적인 근사해법을 사용하였다. 피스톤은 열 경계 조건 없이 크랭크 샤프트의 각도에 따라 압력 부하를 받는다. 시뮬레이션 결과는 피스톤과 커넥팅로드의 응력 집중 위치와 그 값을 예측하고 추정할 수 있다. 그 결과 크랭크 각도 $135^{\circ}$와 $225^{\circ}$에서 피스톤은 190MPa, 커넥팅로드는 123MPa 이상의 최대 등가응력이 나타났으며 이는 인장 항복강도 이하의 값이다. 또한, 커넥팅로드와 피스톤에 계산 된 안전 계수는 1보다 높게 나타났다. 더욱이, 이러한 결과는 왕복동 공기압축기 제작사에 피스톤 및 커넥팅로드를 설계함에 있어서 최적화를 위한 참고 자료로 활용 될 수 있다.

• 대한기계학회논문집B
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• 제23권5호
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• pp.653-660
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• 1999

This work describes analysis on the effect of inlet air cooling by the cold energy of liquefied natural gas(LNG) on the performance of gas turbines. Gas turbine off-design analysis program to simulate the influence of compressor inlet temperature variation is prepared and an inlet air cooler is modeled. It is shown that the degree of power augmentation is much affected by the humidity of inlet air. If the humidity is low enough, that is the water content of the air does not condense, the temperature drop amounts to $18^{\circ}C$, which corresponds to more than 12% power increase, in case of a $1350^{\circ}C$ class gas turbine with methane as the fuel. Even with 60% humidity, about 8% power increase is possible. It is found that even though the fuel contains as much as 20% ethane in addition to methane, the power improvement does not change considerably. It is observed that if the humidity is not too high, the current system is feasible oven with conceivable air pressure loss at the inlet air cooler.

• 설비공학논문집
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• 제27권12호
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• pp.620-625
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• 2015

The summer climate is very hot and humid in Korea. Humidity is an important factor in determining thermal comfort. Recently, research on dehumidification device development has been attempted to save the energy required for operating the dehumidifier. Existing dehumidification systems have disadvantages such as wasting energy to drive the compressor. Meanwhile, dehumidification systems with membranes can dehumidify humid air without increasing the dry bulb temperature. Therefore. they don't have to consume cooling energy. In this paper, the installation conditions for a membrane system were analyzed to improve the shape and optimum performance of the system. The results showed that the distance between elements was the critical system design factor, and that a distance of 20 mm was the optimal condition for the pressure drop and flow characteristics of the internal air flow.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.1225-1231
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• 2006

Recently, as the climate of temperature change has happened worldwide, To solve this problem, Kyoto protocol was taken to regulate global warming on Feb. 2005 and each country is making efforts to prevent global warming. In the automotive industry, R-134a refrigerant is widely used most these days because it has zero ODP(Ozone Depletion Potential). But R-134a GWP(Global Warming Potential) is so high. Therefore, replacement refrigerant desperately is needed as a alternative refrigerant. So, R-l52a is considered as one of the alternative refrigerants due to zero ODP and lower GWP against as required on Europe Committee. In this paper, performance of the air conditioning system between R-134a and R-152a is investigated experimentally. In the bench level, cooling capacity, condensing capacity, COP of automotive air conditioning system are ovaluated by means of air velocity entering the condenser and compressor revolution speed with optimized charge refrigerant quantity. Result of this study, R-152a refrigerant shows the possibility as alternative refrigerant of current R-134a in automotive air conditioning system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.952-954
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• 2003

This paper deals with design of Synchronous Reluctance Motor with conventional laminated rotor for driving an air conditional compressor in a vehicle. To design both stator and rotor, design parameters, such as laminated axial length, rotor diameter, resistance and inductance are considered. The design variables are selected to get the highest power by analyzing the characteristics. The current angle in which torque is maximum is accomplished by finite element method(FEM).

• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.743-749
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• 2010

자동 부침식 가두리 시설을 개발하기 위해 가두리 시설을 구형 부자로 단순화하여 이것의 자동 침하 및 상승 관련 제어 알고리즘 및 프로그램을 개발하였고 실내 수조 실험을 통해 그 유용성을 확인하였다. 또한 기존 연구 결과의 수치와도 비교 분석함으로써 기존 연구의 수치 모델 결과의 유용성을 재확인하게 되었다. 그리고 실물 실험에 대한 선행 연구로써 많은 변수들과 부력에 대한 비선형적인 메커니즘을 제어를 통해 극복하였으며, 이는 실물 실험에 있어 중요한 요소로 작용될 것이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.71-74
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• 2005

More than five pulleys are used in an automobile, such as crankshaft, water pump, air-con compressor, fan and power steering pump pulley. These pulleys are parts that need durability until retiring a car. But there is no design criterion for durability, so pulleys are designed by the experience of designer and trial and error. So, in this study, we carried out stress analysis at durability test condition and compared analysis results to durability test results. It is found that the design criterion for durability is defined as a safety factor and a safety factor is different according to the distance between the center line of v-grooves and the mating surface.