• 대한기계학회논문집
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• 제14권3호
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• pp.656-663
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• 1990

본 연구에서는 이러한 해석적 근사해를 이용한 스터링기관의 최적설계조건에 관하여 취급하고자 한다. 단열해석의 결과를 대응하는 등온해석과 비교, 고찰함으로 써 방법에 따른 조건의 차이를 보이고 주요 설계인자의 성능에 미치는 영향을 규명한 다. 또한, 제인자에 따른 기관성능의 변화추이가 편리하게 표시될 수 이씨는 일종의 성능선도(performance map)를 작성하고자 한다.

• 대한기계학회논문집B
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• 제22권11호
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• pp.1635-1646
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• 1998

The present study investigated the effects of geometric parameters considered on the performance of an automotive scroll compressor by assuming ideal, semi-real and real gases for R-134a. The geometric parameters were center thickness of scroll, height of scroll and the size of discharge port. Fourth-order Runge-Kutta method was applied to solve the thermodynamic equations, leaking rate equation and the equation of motion of discharge valve for ideal, semi-real, and real gases. The volumetric and adiabatic efficiencies for semi-real and real gases differed little, but those for ideal gas differed by 18% and 25% compared with those for real gas at 2,000rpm. The volumetric efficiency changed little as the design angle of scroll (${\gamma}$) changed, but the adiabatic efficiency at ${\gamma}$ of $34^{\circ}$ was higher by 2.4% than that of $147^{\circ}$ for 2,000rpm. The volumetric and adiabatic efficiencies at scroll height of 29.8mm were higher by 1.7% and 2.8% than those of 65.8mm. The volumetric efficiency changed little as the size of discharge port changed, but the adiabatic efficiency increased a little as the size of discharge port decreased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.769-774
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• 2003

In this paper, the performance of a domestic Kim-Chi refrigerator is predicted by using a calculation model & experiment. The objectives of this study are to find out the best design points of a refrigeration system and calculate an adiabatic characteristic to change outdoor temperature. The best design points such as refrigerant charge and capillary length were experimentally investigated. And the calculation model is conducted as a function of calculation parameters and outdoor temperature. According to this study results, the best design points of a refrigeration system are each 95g of a refrigerant charge and 3500/3500mm of capillary lengths. And the power consumption is 13.578 Kwh/month. And a part of the worst heat loss is a front side of a domestic Kim-Chi refrigerator body.

• 한국연소학회지
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• 제3권1호
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• pp.21-29
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• 1998

Mathematical modeling of combustion characteristics in HVOF thermal spray processes was carried out on the basis of equilibrium chemistry. The main objective of this work was the development of a computation code which allows to determine chemical composition of combustion products, adiabatic flame temperature, thermodynamic and transport properties. The free energy minimization method was employed with the descent Newton-Raphson technique for numerical solution of systems of nonlinear thermochemical equations. Adiabatic flame temperature was calculated by using a Newton#s iterative method incorporating the computation module of chemical composition. The performance of this code was verified by comparing computational results with data obtained by ChemKin code and in the literature. Comparisons between the calculated and measured flame temperatures showed a deviation less than 2%. It was observed that adiabatic flame temperature augments with increase in combustion pressure; the influence was significant in the region of low pressure but becomes weaker and weaker with increase in pressure. Relationships of adiabatic flame temperature, dissociation ratio and combustion pressure were also analyzed.

• 한국수소및신에너지학회논문집
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• 제34권3호
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• pp.316-326
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• 2023

Development of carbon-neutral fuel production technologies to solve climate change issues is progressing worldwide. Among them, methane can be produced through the synthesis of hydrogen produced by renewable energy and carbon dioxide captured through a CO₂ methanation reaction, and the fuel produced in this way is called synthetic methane or e-methane. The CO₂ methanation reaction can be conducted via biological or thermochemical methods. In this study, a 30 Nm³/h thermochemical CO₂ methanation process consisting of an isothermal reactor and an adiabatic reactor was used. The CO₂ conversion rate and methane concentration according to the temperature measurement results at the center and outside of the adiabatic reactor were analyzed. The gas flow into the adiabatic reactor was found to reach equilibrium after about 1.10 seconds or more by evaluating the residence time. Furthermore, experimental and analysis results were compared to evaluate performance of the reactor.

• 대한기계학회논문집B
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• 제25권8호
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• pp.1131-1139
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• 2001

Experimental results are presented, which describe the effect of blowing ratio on film cooling from two rows of holes with opposite orientation angles. The inclination angle is fixed at 35°, and the orientation angles are set to be 45°for the downstream row, and -45°for the upstream row. The studied blowing ratios are 0.5, 1.0 and 2.0. The boundary layer temperature distributions are measured using thermocouple at two downstream locations. Detailed adiabatic film cooling effectiveness and heat transfer coefficient distributions are measured with TLC(Thermochromic Liquid Crystal). The adiabatic film cooling effectiveness and heat transfer coefficient distributions are discussed in connection with the injectant behaviors inferred from the boundary layer temperature distributions. Film cooling performance, represented by heat flux is evaluated from the adiabatic film cooling effectiveness and heat transfer coefficient data. The results show that the investigated geometry provides improved film cooling performance at the high blowing ratios of 1.0 and 2.0.

• 한국염색가공학회지
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• 제35권2호
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• pp.128-136
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• 2023

Recently, the automobile industry is developing as the demand for automo- biles increases due to industrial development and population growth. In addition, many studies are being conducted to reduce heat loss inside the automobiles in order to save energy inside the automobiles due to environmental regulations. In this study, alumina, nanosilicon, and aerogel, which are adiabatic materials, were filled in PET to manufacture yarn, identify physical and mechanical properties, and weave into fabric to confirm adiabatic performance. As the content of the adiabatic material increased, the tensile strength of the fibers filled with alumina and nanosilicon decreased greatly, and the adiabatic property slightly increased. The tensile strength of fibers filled with the aerogel decreased slightly, but the adiabatic properties were greatly increased. Therefore, it is considered to be due to the large volume fraction in the PET yarn due to the low density of the aerogel.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.28-32
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• 2003

Miniature inertance pulse tube refrigerator was designed and fabricated to provide optimal performance with 10W compressor. An adiabatic model was used to design an inertance pulse tube refrigerator. Among the various design parameters which should be optimized, pulse tube length and inertance tube length were considered. PdV work and various losses were calculated for various pulse tube and inertance tube length. Experiments were carried out for different pulse tube length and inertance tube length. It was shown that the experimental results were similar to the calculated results. The reason why the quantitative optimal point exists is explained.

• 설비공학논문집
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• 제7권1호
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• pp.150-160
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• 1995

A Finkelstein adiabatic analysis is performed for Stirling refrigerator with real gas properties of helium. The mass balance and the energy balance equations are formulated into the form that is convenient for incorporating an available computer code of the helium properties. The differential equations are solved numerically. The calculated coefficient of performance(COP) and the pressure variation are compared with the results obtained when helium is assumed to be an ideal gas. The relative errors in COP are presented as functions of the refrigeration temperature and the maximum cycle pressure.

• 한국생산제조학회지
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• 제21권4호
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• pp.582-587
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• 2012

Recently, the low-emissivity glass has been used to reduce the energy loss through building windows. However, it simply reduces the inflow of solar rays and has a relatively high heat transmission coefficient. To solve the problems, a high-efficiency vacuum glazing has been under development but it has not been actively used due to its high price and insufficient performance. In this paper, the effects of internal pressure, pillar (spacer) height, pillar diameter, pillar interval, emissivity etc. on the performance of vacuum glazing have been analyzed with three-dimensional computational fluid dynamics and structural analysis. As a result, the performance of vacuum glazing was predicted more accurately and major factors that determine the performance of vacuum glazing were optimized.