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원성필,이동환,Won Sung Pil,Lee Dong Hwan 대한설비공학회 1987 설비저널 Vol.16 No.2
The heat loss of a building within a wind flow field results from convection and natural ventilation. Loss from natural ventilation is much more than one from convection, and the former depends mostly on the pressure distribution at the building surface. Therefore, the objective of the present study is to calculate the pressure distribution and investigate flow phenomena, around the building with a rectangular shape in a two-dimensional turbulent flow field. The finite difference method, modelled upon the turbulence $k-\epsilon$ model, has been applied to the analysis. The results, followed by the changes of Reynolds numbers, inlet flow conditions, and building shapes, have been also obtained, respectively. Various results of the present numerical analysis coincide qualitatively well with earlier reported empirical results.
원성필,노승탁,Won, Sung-Pil,Ro, Sung-Tack 대한설비공학회 1981 설비저널 Vol.10 No.1
The Enthalpy Model was verified in order to analyze two- dimensional phase change problems. By using the Enthalpy Model, interface locations, frozen fraction rates, heat flux distribution rut cooled surfaces, and surface-integrated heat flux were purely numerically calculated in rectangular thermal storage units, whose initial condition was saturated liquid and phase change material was cooled on its boundaries by convective heat transfer. The calculations were performed for various Stefan numbers and Biot numbers. The effect on those dimensionless numbers were explained.
원성필,김민수,김동섭,노승탁,Won, S.P.,Kim, M.S.,Kim, T.S.,Ro, S.T. 대한설비공학회 1990 설비공학 논문집 Vol.2 No.2
A theoretical cycle analysis has been performed for a basic heat pump, charged with non-azeotropic refrigerant mixtures, R22/R114 and R13B1/R152a. At first, a procedure is introduced to calculate thermodynamic properties simply and correctly, and the advantages of using refrigerant mixtures are discussed through the cycle analysis. It is shown that by using refrigerant mixtures in the heat pump, several improvements can be made. In comparison with conventional pure refrigerants, the application of refrigerant mixtures results in high reliabilities caused by the extension of the application limit, energetic improvements, and a continuous capacity control. From generalizing various results, the optimum compositions in refrigerant mixtures are also determined. The 30%/70% and 40%/60% compositions are selected for R22/R114 and R13B1/R152a, respectively.
원성필 울산대학교 1985 연구논문집 Vol.16 No.1
本 論文은 두 境界面이 서로 다른 온도로 일정하게 유지되는 密閉된 直四角空洞內의 空氣層의 自然對流에 관한 연구로써 數値的方法과 實驗을 通하여 解析하였다. 間隔比의 변화와 Grashof數의 변화가 空洞內의 열전달에 미치는 효과를 분석하였으며 특히 여러 流動段階에 대한 定性的인 분석이 수치해석을 통하여 세밀하게 이루어졌다. 수치해석과 실험을 통한 Nud數, Grd數 및 간격비 사이의 관계식이 최종적으로 다음과 같이 각각 제시되었다. 수치해석결과 : Nu=0.255Gr(L/D)-0.224 10≤Gr≤10 2≤L/D≤40 실 험 결 과 : Nu=0.249Gr(L/D) 5×10≤Gr≤4×10 4.94≤L/D≤60.24 Laminar natural convection in an air layar contained in a vertically rectangular cavity with isothermal side walls at different temperatures has been investigated numerically and experimentally. It has been described what effect is reflected on heat transfer as the Grashof number and the aspect ratio are changed. Especially, the velocity profile, the temperature profile, and the isotherm configuration were analyzed with the various flow-regimes through the numerical method. Two Nusselt-Grashof correlations were presented using the numerical and the experiment, respectively as follows ; Numerically : Nu=0.255Gr(L/D)-0.224 10≤Gr≤10 2≤L/D≤40 Experimentally : Nu=0.249Gr(L/D) 5×10≤Gr≤4×10 4.94≤L/D≤60.24
남궁 규완,안강수,원성필 울산대학교 1996 공학연구논문집 Vol.27 No.1
본 연구는 동판, 탄소강판, 스테인레스강판의 가열면상 증류수 액적의 증발시간 및 표면의 온도변화에 대한 것으로 가열면의 초기온도는 핵비등이 존재하는 최저온도로부터 최고 온도 영역의 범위 내에서 논했다. 액적 밑면의 가열면 온도는, Rohsenow가 제시한 푸울 핵비등 열전달 관계식을 사용하여, 2차원 천이 열전도 해석으로부터 계산했으며, 가열면 재질 및 초기 액적크기 등에 따라 합리적인 변화 결과를 얻었다. 또한 본 연구에서 제시한 액적증발 모델은 액적과 가열면간의 접촉면적 변화를 계산하는데 사용되었다. 시간에 의존하는 접촉면 온도와 액적의 기하학적 형상 변화로부터, 특정 액체/고체조합에서 전 증발시간을, 초기 가열면 온도와 초기 액적 크기와 관련하여, 예측했다. This paper discusses the evaporation time of a pure water droplet on smooth surface of copper, carbon steel and stainless steel. The initial surface temperature ranges from the lowest limit to the highest limit of the nucleate boiling region. The surface temperature just below the droplet is calculated from the 2 dimensional transient conduction, using the transfer correlating equation of nucleate pool boiling proposed by Rohsenow. And the evaporation model proposed in this paper is used to calculate the changes of contact area between liquid droplet and heated surface. With these time dependent values of surface temperature and those of geometrical shape of droplet, the total evaporation time for a specific liquid-solid combination can be predicted as the initial surface temperature and the initial droplet size. The predicted evaporation times are compared with the experimental data. Though the present model consists of some assumptions which include bubble waiting time, heat transfer coefficient and the shape of liquid droplet on surface, the predictions and measurements are in good agreement.