• 대한기계학회논문집
• /
• 제13권6호
• /
• pp.1231-1237
• /
• 1989

본 연구에서는 이러한 단열해석상의 문제점을 해결하기 위한 하나의 방식이 광방법으로서 적절한 가정을 도입하여 단열모델에 대한 해석적인 근사해를 시도하였다. 실제조건에 부합하면서도 간편하며 경제적인 해석방법의 확립은 VM 사이클로 작동되는 냉동기에 대한 최적설계의 중요한 기초가 될 것이다. 해석모델의 정립, 종속변수에 대한 근사해, 성능평가에 필요한 열역학적량들을 종속변수의 해석적 함수형태로 표시하는 과정을 내용에 포함한다.

• 한국안전학회지
• /
• 제13권4호
• /
• pp.142-154
• /
• 1998

A stirling engine is a mechanism used to convert heat to power and operates on a closed regenerative thermodynamic cycle with compression and expansion of the working fluid at different temperature. The performance of a stilting cycle machine is a function of six independent parameters, namely; (1) speed N(r.p.m), (2) pressure of the working fluid p(Pa), (3) ratio of the temperature in the compression and expansion space ${\tau}(=T_C/T_E)$ , (4) ratio of the swept volumes in these two spaces K, (5) phase angle $\alpha$ and (6) dead volume ratio X. This paper describes the procedure and presents the results of computations carried out to establish the optimum combinations of these six parameters for maximum engine output for the machine acting as a prime mover, over a combined temperature range from $300^{\circ}K$ to $1000^{\circ}K$ and dead volume ratio X ranging from 0.1 to 2.0. The output of a stilting cycle machine can be expressed in terms of nondimensional power in several different ways. Four methods were studied in detail, the parameters optimized and design charts and engine power charts prepared. The results of this paper may be useful as a guide to the likely effects on the performance of some of the important design parameters and regenerator design.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2003년도 하계학술대회 논문집
• /
• pp.160-160
• /
• 2003

• 설비공학논문집
• /
• 제21권2호
• /
• pp.94-102
• /
• 2009

Conceptual design of scroll expander and scroll compressor for 10kW-class Stirling engine utilizing solar energy as heat source has been carried out to estimate the applicability of scroll mechanism for Stirling cycle. CO2 was chosen as working fluid, since it has lower expansion index and higher density among probably usable gases. Gas temperature at the expander inlet was set at $700^{\circ}C$, and that at the compressor inlet was at $40^{\circ}C$. System efficiency reached maximum at the pressure ratio of about 2.5, and the peak efficiency increased with increasing high side pressure. Due to safety concern, the pressure condition of 6 MPa/2.5 MPa was chosen as design condition. Orbiting scroll members for the expander and compressor were designed to have double-sided structure in order to reduce the overall scroll size and to cancel out the axial gas forces acting on the orbiting scroll base plate. By parametric study on the scroll profile, smaller possible size for the scroll members was obtained. With the shaft speed of 3600rpm, the shaft output of the designed scroll expander was calculated to be 45.4kW, while input power for the scroll compressor was 34.5kW, yielding 10.9kW for the output power of the Stirling engine. System efficiency was estimated to be about 7.3%, and overall efficiencies of the scroll expander and compressor were around 84.1% and 88.3%, respectively.

• Nuclear Engineering and Technology
• /
• 제54권4호
• /
• pp.1482-1494
• /
• 2022

Power conversion cycles (Subcritical Steam, Supercritical Steam, Open Air Brayton, Recuperated Air Brayton, Combined Cycle, Closed Brayton Supercritical CO₂ (sCO₂), and Stirling) are evaluated for land-based nuclear microreactors based on technical maturity, system efficiency, size, cost and maintainability, safety implications, and siting considerations. Based upon these criteria, Air Brayton systems were selected for further evaluation. A brief history of the development and applications of Brayton power systems is given, followed by a description of how these thermal-to-electrical energy conversion systems might be integrated with a nuclear microreactor. Modeling is performed for optimized cycles operating at 3 MW(e) with turbine inlet temperatures of 500 ℃, 650 ℃ and 850 ℃, corresponding to: a) sodium fast, b) molten salt or heat pipe, and c) helium or sodium thermal reactors, coupled with three types of Brayton power conversion units (PCUs): 1) simple open-cycle gas turbine, 2) recuperated open-cycle gas turbine, and 3) recuperated and intercooled open-cycle gas turbine. Aeroderivative turboshaft engines employing the simple Brayton cycle and two industrial gas turbine engines employing recuperated air Brayton cycles are also analyzed. These engines offer mature technology that can facilitate near-term deployment with a modest improvement in efficiency.

• 대한기계학회논문집B
• /
• 제38권6호
• /
• pp.475-482
• /
• 2014

본 연구는 스프레이 열전달을 이용한 저온도차 스털링 엔진의 실험적 개념 연구를 제시한다. 스프레이 열교환기는 노즐을 통하여 엔진 작동 공간에 직접 물을 분사함으로써 엔진 성능을 저해하는 불용 공간을 최소화하고 열전달 효율을 높였다. 직접 구현된 실험 스털링 엔진의 실증 실험은 운전 시점의 기동 특성, 정상 상태의 운전 특성, 엔진의 출력 특성에 대하여 진행하였다. 실험 결과, 열수 유량 증가에 대하여 엔진 기동 시 작동 최소 온도는 감소한 반면, 고온부 온도와 고온부-저온부 온도차는 대체로 일정하였다. 정상 상태 운전의 경우 열수 온도 및 유량 증가에 대하여 작동 주파수는 증가하였다. 엔진 출력은 열수 온도 및 유량 증가에 따라 사이클당 일 및 작동 주파수 증가로 인하여 증가하였다. 본 연구에서 구현된 실험 스털링 엔진은 열수 유량 30 ml/min, 열수 온도 $65^{\circ}C$, 고온부-저온부 온도차 $6^{\circ}C$ 이상에서 엔진 출력 0.05W 수준으로 안정된 기동 및 운전 특성을 보였으며, 향후 출력 증가 및 다양한 적용 연구를 지속할 계획이다.

• 연구논문집
• /
• 통권34호
• /
• pp.39-46
• /
• 2004

The compressors in the air conditioner have the role of the pressurization and circulation of the refrigerant. The hermetic reciprocating compressors driven by rotary motor have been used for the air conditioner. The linear compressor has very simple structure and enhancement in the efficiency in comparison to that of conventional reciprocating compressor. The linear compressors are widely used for the small cryogenic refrigerator (below 1 kW), such as the Stirling refrigerator and pulse tube refrigerator. In the cryogenic application, the pressure ratio of the linear compressor is below 1.5, but the linear compressor for the air conditioner should overcome the high pressure ratio and the large pressure difference between the each sides of the piston. The resonance characteristics of the linear compressor has the significant impacts on the power consumption. To minimize the power consumption, the linear compressor should be operated at the resonance point. In the resonance characteristics, the role of the mechanical and gas spring should be considered. In present study, the cycle of the analysis of the vapor compression refrigeration cycle with the different refrigerants (R134a, R4l0a, R600a) and the designs of the linear compressor are performed. The effects of the stiffness of the mechanical spring on the electromagnetic forces would be discussed. Finally, the results show the design specification of the linear compressor for the air conditioner.

• Journal of Advanced Marine Engineering and Technology
• /
• 제18권2호
• /
• pp.1-17
• /
• 1994

잠수함추진방식은 크게 원자력 추진과 재래식 추진으로 나눌수 있다. 최근에는 재래식 추진방식과 하이브리드 개념으로 운용될 수 있는 AIP(Air Independent Propulsion)방식도 활발히 연구되고 있다. AIP추진으로는 폐회로 디젤기관추진(Closed Cycle Diesel Engine Propulsion), 연료전지추진(Fuel Cell Propulsion), 스터링기관추진(Stirling Engine Propulsion) 및 폐회로터빈추진(Closed Cycle Turbin Propulsion) 등이 있다. 이러한 잠수함 추진체계에 대해 앞으로 크게 세부분으로 나누어 그 현황과 발전추세를 살펴보고자 한다. 즉, 초기의 순수전기추진방식으로 불리는 재래식 추진체계, 재래식 추진방식의 한계를 극복하기 위해 최근 활발히 연구되고 있는 외기와 무관한 추진장치인 폐회로 추진체계, 그리고 궁극적으로는 에너지의 문제로 귀착되어 거의 무한대의 에너지원을 가지고 있는 원자력 추진체계로 구분하여 그 현황과 발전내용을 살펴 봄으로써 잠수함추진체계의 국내연구 개발방향정립에 조금이나마 보탬이 되었으면 합니다. 또한 차세대 추진장치로 불리는 전자유체 추진방식에 대해서는 한국박용기관 학회지 1993년 4월호 "박용전자유체(MHD) 추진장치"를 참조하시기 바랍니다.조하시기 바랍니다.

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
• /
• pp.7-11
• /
• 1999

The recent progress in new cooling techniques of the high Tc superconductor(HTS) systems is reported and discussed with some practical examples. At the beginning stage of the HTS development in research laboratories, liquid nitrogen(LN$_2$) is the standard medium for an effective cooling. The success of HTS in many different application areas, however, has required a variety of need in the cooling temperature and the cooling capacity with specific design restrictions. While the utilization of alternative liquid cryogens such as liquid neon (LNe) or liquid hydrogen (LH$_2$) has been tired in some of them, even solid cryogens such as solid nitrogen (SN$_2$) or solid hydrogen (SH$_2$) may be another option in special applications. The gaseous helium cooled by a cryogenic refrigerator has also been a good candidate in many cases. One of the best cooling methods for the HTS is the direct conduction-cooling by a closed-cycle refrigerator with no cryogen at all. The refrigeration may be based on Joul-Thomson, Brayton, Stirling, Gifford-McMahon, or pulse tube cycles. The pros and cons of the newly proposed cooling methods are described and some significant design issues are presented.

• 설비공학논문집
• /
• 제8권1호
• /
• pp.88-98
• /
• 1996

The present study is concerned with the flow friction and heat transfer characteristics of the combination of various regenerator materials, using the different Darcy number and porosity, which is filled uniformly and partially in a tube under oscillating flow condition. The poros medium is adopted as Brinkmann-Forschheimer extended Darcy model. Numerical results are obtained or the flow and temperature fields and described the effect of the combination of various regenerator materials and Womersley number on the pressure drop, the heat transfer and the regenerator efficiency. The results obtained indicate that not only heat transfer between the tube wall and oscillating flow but also the pressure drop at both ends of the regenerator are increased, while the regenerator efficiency is decreased in the increase of womersley number. It is also found that the friction factor is increased as Reynolds number is increased. The comparison between the combination of the various regenerator materials and the homogeneous regenerator material shows that the regenerator efficiency can be enhanced with the proper combination of various regenerator materials even though the averaged porosity of the regenerator is same.