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신현준,서정윤,Shin, H.J.,Seo, J.Y. 대한설비공학회 1993 설비공학 논문집 Vol.5 No.3
Thermosyphons are simple devices that can passively transport thermal energy over relatively large distance with little temperature degradation. Especially, the thermosyphon system requires no costly energy input and is completely maintenance free. These attributes permit the use of low grade thermal energy for thermal control of structures including the stabilization of highway foundations. This paper presents the experimental results of the snow melting system in which thermosyphon was utilized to ransfer the earth energy to the pavement to remove snow and ice. The test facility, three earth heated and one unheated test panels, is designed to investigate the variables associated with removing snow and ice from pavement surfaces. The results of these test show that the earth heated panel surface temperature is higher $2{\sim}6^{\circ}C$ than unheated panel when the ambient air temperature is $-7^{\circ}C$. The thermal performance of this earth source thermosyphon system for road heating showed that there was no snow on the heated test panels when the snowfall was 5cm average for the region.
이용화(Y.H.Lee),이동호(D.H.Rie),카시와기타카오(T.Kashiwagi),서정윤(J.Y.Seo) 한국태양에너지학회 1995 한국태양에너지학회 논문집 Vol.15 No.1
본 연구는 H₂0/LiBr 과 NH₃/ H₂O계를 사용하는 2단2원 흡수식 사이클의 특성에 관한 연구이다. 이 사이클은 2개의 단효용 사이클로 이루어져 있으며, 저온단의 흡수기와 응축기에서 얻어진 열을 고온단의 증발기에서 이용하는 사이클로서 저온단의 증발기 및 응축기의 온도, 재생기 온도, 열교환 온도차를 파라메터로 하여 계산한 결과 다음과 같은 결론을 얻었다. 2단2원사이클의 성립범위를 확인하였으며 본 계산조건에서 50~70℃의 승온폭을 얻을 수 있었다. 또한 50℃의 난방온도를 얻기위한 최적재생온도는 105℃, 최대 COP를 얻기위한 저온측사이클의 응축압력은 16℃, 그리고 이 조건에서 저온측 사이클으 응축압력을 단효용 사이클의 경우보다 낮게 억제하는 것이 가능함을 알았다. This paper concerns the study of a two-stage binary absorption cycle employing the refrigerant/ absorbent combinations of LiBr / H₂0 and NH₃/ H₂O. This cycle consists of coupling two single-effect absorption cycles so that the first stage absorber and condenser produces heating water to evaporate refrigerant in the evaporator of the second stage. The effect of operating variables such as evaporator temperature, condenser and absorber temperature, and generator temperature on the coefficient of performance and temperature lift have been studied for two-stage binary absorption heat pump systems. It is found that this cycle has a large temperature lift at 105℃ of optimum generator temperature to obtain 50℃ of condenser temperature.
목인균,서정윤,김종보,Mok I. K.,Seo J. Y.,Kim C. B. 대한설비공학회 1986 설비저널 Vol.15 No.4
Numerical solutions of two-dimensional, steady, and natural are investigated in a confined rectangular cavity with porous media. The saturated fluid is bounded by two isothermal vertical walls at different temperatures and two adiabatic horizontal walls. Governing equations are numerically solved by finite difference method with the up wind scheme. Distributions of streamline and temperature we. predicted for aspect ratios ranging from 0.1 to 1.0, Rayleigh numbers 50 to $10^4$, and tilt angles $0^{\circ}\;to\;60^{\circ}$. Representative plots of temperature and velocity field according to tilt angle are presented. The effects of aspect ratio, Rayleigh number, and tilt angle on local and average Nusselt numbers are obtained. The optimum conditions for maximum Nusselt number are also presented with tilt angles.
충돌분류계(衝突噴流系)에서 난류촉진체(亂流促進體)에 의한 방열효과(放熱效果)에 관(關)한 연구(硏究)
이용화,서정윤,Lee, Y.H.,Seo, J.Y. 대한설비공학회 1992 설비공학 논문집 Vol.4 No.1
The purpose of this study was to investigate the enhancement of heat transfer without additional external power in the case of rectangular air jet impinging vertically on the flat heating surface. In an attempt to enhance the heat transfer rate in two-dimensional impinging jet, the technique used in the present study was placement of square rod bundles as a turbluence promoter in front of the heat transfer surface. The effects of the clearance between the flat plate and square rod, and the nozzle exit velocity on the heat transfer characteristics have been investigated experimentally. The results obtained through this study were summerized as follows. High heat transfer enhancement was achived by means of flow acceleration and thinning of boundary layer by inserting rods in front of the heating flat plate. The smaller the clearance between rod and heating plate was, the larger heat transfer effect became. Average Nusselt number reached maximum at $Re=5.76{\times}10^4$ and C=1㎜ and the enhancement rate of heat transfer became maxium at this condition with the enhancement ratio as high as about 1.427 when normalized by the flat plate value. The correlating equation of average Nusselt number and Reynolds number was obtained, which is $\bar{N}uo=1.324{\cdot}Re^{0.459}{\cdot}(C/A)^{-0.034}$.
양한주,서정윤,Yang, H.J.,Seo, J.Y. 대한설비공학회 1990 설비공학 논문집 Vol.2 No.3
In this study, heat transfer characteristics of vertical fixed bed with air flowing through were experimentally investigated. The experiments were conducted for cases where heat was transfer steady state conditions from an immersed cylindrical heated to the surrounding fixed ved of steel balls. Based on the experimental data, the optimum conditions for heat transfer augmentation have been determined and shows in empirical forms. For the same power loss, comparison of heat transfer effect between the fixed bed and single phase forced convection device indicates that both miniaturization of heat exchange device and heat transfer augmentation at low flow velocity are possible by application of the fixed bed to heat exchangers. The present results could provide a useful design information for the heat exchangers where fixed beds are used.
충돌공기분류계(衝突空氣噴流系)에서 난류촉진체(亂流促進體)의 폭변화(幅變化)가 전열증진(傳熱增進)에 미치는 영향(影響)
금성민,서정윤,Kum, S.M.,Seo, J.Y. 대한설비공학회 1994 설비공학 논문집 Vol.6 No.4
This experimental study was earned out to examine the heat transfer characteristics of a 2-dimensional impinging air jet on a flat plate with a set of square rods. The objectives of the study were to investigate the flow and heat transfer characteristics caused by the square rods and to find out the optimum rods arrangement. Experiment was carried out first without using the rods to establish the baseline heat transfer performance. Then, rods of different widths and clearances were installed to cause the turbulence on the fluid flow.
냉매의 소결금속관 표면에서의 비등 열전달에 관한 실험적 연구
박찬준,문병수,서정윤,Park C. J.,Mun B. S.,seo J. Y. 대한설비공학회 1981 설비저널 Vol.10 No.3
The purpose of this paper is to investigate the potential ability of sintered metal tube to promote heat transfer. In the experiment for Freon - 11, the boiling heat transfer on the sintered metal tube of bronze element is investigated and compared with that of the bronze tube (bare tube) atmospheric pressure. The experimental results are obtained as follows : 1) For sintered metal tubes of bronze element with particle diameters which ranges from $79({\mu})\;to\;461({\mu})$ and bare tube, boiling characteristic curves are expressed as : a) Sintered metal tube $$q{\propto}{\Delta}T^{1.05\~1.373}$$ b) Brae tube $$q{\propto}{\Delta}T^{3.096}$$ 2) Compared with that of the bare tube at low temperature difference$({\Delta}T_{sat})$, boiling heat transfer coefficient of the sintered bronze tube are relatively high. 3) There is tendency that curves of boiling heat transfer coefficients of sintered ·bronze tube and bare tube approach each other at rather high temperature difference. It is due to the increasing rate of the former heat transfer coefficient along with temperature difference is smaller than that of the latter. 4) Referring to particle diameter, optimum condition, i. e. , maximum heat transfer coefficient is found to be at approximately 2 mm thickness of sintered layer with $D_p=150({\mu})$.