• 설비공학논문집
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• 제20권10호
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• pp.645-653
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• 2008

Spiral-jacketed thermal storage tanks can greatly simplify solar heating systems while maintaining the thermal performance at a similar level as conventional systems with an external heat exchanger. Proper design of the spiral-jacket flow path is essential to make the most of solar energy, and thus to maximize the thermal performance. In the present work, computational fluid dynamics (CFD) analysis was carried out for a spiral-jacketed storage tank installed in a solar heating demonstration system. The results of the CFD analysis showed a good agreement with experimentally determined thermal performance indices such as the acquired heat, collector efficiency, and mixed temperature in the storage tank. This verified CFD modelling approach can be a useful design tool in optimizing the shape of spiral-jacket flow path and the flow rate of circulating fluid for better performance.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.346-351
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• 2006

When metallic alloys are reacted to hydrogen, heat transfer of storage tank effects hydrogen storage rate and capacity. If pulsating heat pipe are used to improve heat transfer efficiency, production of hydrogen storage tank can be more simple and economical. Experiment of heat pipe was conducted by varying working fluids and heat flux. According to supply heat flux, test indicate that R-22 and R-l42b were found lower temperature difference between evaporator and condenser than R-134a and Ethanol. Thermal resistances of R-22 and R-142b were also lower than others. Using R-142b as a working fluid, heat pipe type hydrogen storage tank is tested in absorption and desorption processes.

• 한국초전도ㆍ저온공학회논문지
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• 제24권2호
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• pp.27-38
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• 2022

Urban air mobility (UAM) has recently attracted lots of attention as a solution to urban centralization and global warming. Electric vertical take-off and landing (eVTOL) is a concept that emerges as one of the promising and clean technologies for UAM. There are two difficult challenges for eVTOL aircraft to solve. One is how to improve the weight efficiency of aircraft, and the other is how to complete long-range missions for UAM's flight scenarios. To approach these challenges, we propose a consolidated concept design of battery-fuel cell hybrid tiltrotor aircraft with a liquid hydrogen (LH₂) fuel tank. The efficiency of a battery-fuel cell hybrid powertrain system on the designed eVTOL aircraft is compared to that of a battery-only powertrain system. This paper shows how much payload can increase and the flight scenario can be improved by hybridizing the battery and fuel cell and presenting a detailed concept of a cryogenic storage tank for LH₂.

• 대한설비공학회지:설비저널
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• 제9권2호
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• pp.93-103
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• 1980

A small domestic solar water heating system in thermosyphonic flow was tested in Seoul. The system consisted of four flat plate aluminium roll bond type collectors of total effective area $3.28m^2$ and a $280{\iota}$ storage tank. It was tilted $52^{\circ}$ relative to the horizon. And the collector plate, collector tube and storage tank were equiped with 14 thermocouples. As the results, the following facts were found; 1) To provide water at $55^{\circ}C$ for a family of four in Seoul, a collector area of $3-4m^2$ and a storage capacity of $180{\iota}- 200{\iota}$ are suggested. And this system can supply hot water at above $45^{\circ}C$ day about. 2) In the late afternoon hours, it might be advantageous to stop the flow in the system as heat losses to the environment increase unduly. 3) Without any hot water consumption throughout the day, water temperature distributions inside the storage tank was found almost linear. This indicates essentially no mixing inside the storage tank. 4) In case of a small domestic solar water heating system, it is better to employ a single transparent cover rather than double one.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.793-802
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• 2024

In the framework of the European project SAMOSAFER, this numerical study focuses on some thermal aspects of the Emergency Draining Tank (EDT) located underneath the core of a Molten Salt Reactor. In case of an emergency, this tank passively receives the liquid fuel salt and is designed to ensure a subcritical state. An important requirement is that the fuel does not overheat to maintain the EDT Hastelloy container integrity. The present EDT is based upon a group of hexagonal cooling assemblies arranged in a hexagonal grid and cooled down thanks to conduction through the inert salt layer up to an air flow in charge of removing the heat. This numerical thermal study relies on a conjugated heat transfer analysis coupling a Finite Element solid thermal code (SYRTHES) and two instances of a Finite Volume CFD codes (Code_Saturne). Calculations on an initial design suggest that a simple center airpipe flow is likely to not sufficiently cool the device. Alternative solutions have been evaluated. Introduction of fins to enhance the heat transfer do not bring a noticeable improvement regarding maximum temperature reached. However, a solution in which the central pipe air flow is replaced by several cooling channels located closer to the fuel is investigated and suggests a better cooling.

• 설비공학논문집
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• 제1권1호
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• pp.46-54
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• 1989

The purpose of this study is to obtain the dynamic characteristics of an absorption refrigerator powered by solar energy by experiments. Since the absorption refrigerator power by solar energy should have the characteristics which is suitable for the intermittence and rarity of solar energy, not only the characteristics of the steady state operations but also the partial load and the transient operations should be considered. The minimum available temperature of the storage tank should be known, and the absorption refrigerator can be suitably selected for air-conditioning systems. In this study, the experimental data of the transient state for on-off and warming-up operations has been obtained. Also the experiments are performed which test the minimum available temperature of the storage tank. The results show that it takes 1 hour to get to the steady state of the absorption refrigerator, and the minimum available temperature of the storage tank is about $68^{\circ}C$, and show that in the partial load operations the performance of the absorption refrigerator is improved by applying the modified control method to on-off operations.

• 한국군사과학기술학회지
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• 제17권2호
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• pp.197-203
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• 2014

In this paper, the effect of unsteady radiation on the horizontal fin of an external fuel tank by flame of a flying flare was analysed to see the temperature increase of the fin and the thermal impact on the fin. Radiation between two surfaces was calculated using the concept of radiation resistance of surface and space including radiation, irradiation and shape factor for two flying trajectories of a flare, maximum temperature of 2200 K, emissivity of 0.95, flying velocity of 30 m/s, and thermal surface area of $0.01m^2$. The result shows that the temperature increase of the fin is 0.236 K, and the thermal effect on the fin is ignorable. And it was found that temperature is increased a little because small amount of heat energy can be radiated due to the short exposure time to the heat source.

• 대한조선학회논문집
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• 제34권2호
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• pp.1-10
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• 1997

예인수조에서 저항추진 성능을 추정하기 위한 선형시험을 수행한 때는 계측정도에 나쁜 영향을 주는 불안정현상에 유의하여야 한다. 불안정현상을 일으키는 큰 원인인 수조수 수심에 따른 수온의 불균일, 연중 수온의 변화, 난류촉진장치, 저항시험 사의 이복현상에 대해 검토하였다. 그리고 수조수 순환, 수조동 난방, 탈기장지 및 난류촉진장치의 개선 등을 그 해결 방안으로 제시하였다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.768-773
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• 2009

A numerical study has been performed to investigate the thermal Performance of Solar heating system with baffle type of storage tank by using the commercial code TRNSYS. As a result, the solar fraction depends strongly on the efficiency and heat loss coefficient of solar collector as well as the heating capacity of house and the water temperature supplied to the shower. In addition, the solar fraction has been basically ranked to higher level in baffle type of storage tank than typical type of single storage tank for the range of operation condition.

• 한국가스학회지
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• 제15권5호
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• pp.50-56
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• 2011

엔진의 제동시의 유효일을 이용하여 고압의 압축 공기를 저장하고 운전 시에는 저장된 압축 공기를 동력원으로 사용하는 신개념의 Air hybrid 엔진의 구현 가능성 검토를 위한 실험적인 연구를 진행하였다. Air hybrid 엔진 시스템의 구현을 위하여 연구용 단기통엔진을 개조하였고, 배기 밸브 중의 하나에 독립 가변 밸브리프트 시스템을 장착하여 압축 행정 동안에 고압의 공기를 저장할 수 있도록 하였다. 또한, 엔진의 구동을 위하여 점화플러그 위치에 공기 분사 모듈을 장착하여 팽창행정 중에 고압의 공기를 분사할 수 있도록 하였다. 압축 공기 저장 모드에서는 800rpm 아이들 조건에서 800 사이클 동안 30리터의 공기 저장 탱크를 최대 13 bar 까지 충전할 수 있었고, 충전된 고압의 공기를 이용하여 800rpm 아이들 조건에서 0.41 bar의 평균도시유효압력의 일을 얻을 수 있었는데 이것은 정상적인 아이들 조건보다 1.1 bar의 유효일이 증가한 것이다.