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박희용,이흥주,강건,Pak, H.Y.,Lee, H.J.,Kang, Kun 대한설비공학회 1989 설비공학 논문집 Vol.1 No.2
The steady one dimensional heat flow method was used for the measurement of thermal conductivity of kaolin. The effects of the classification, density and moisture content on the thermal conductivity were studied experimentally for the 9 classes of kaolin in Korea. As the results of this study, it was found that the classification did not effect the thermal conductivity, and the conductivity increased as the density and moisture content increased. The correlation equation of the thermal conductivity as a function of the density increase rate was found and the values for the thermal conductivity as a function of moisture content were recommended.
박희용,박경우,Pak, H.Y.,Park, K.W. 대한설비공학회 1994 설비공학 논문집 Vol.6 No.3
The Combustion gas behavior induced by fire in a building is numerically investigated. The typical building for this analysis is partially divided by a vertical baffle projecting from the ceiling. The solution procedure includes the low Reynolds number ${\kappa}-{\varepsilon}$ model for the turbulent flow and the discrete ordinates method is used for the calculation of radiative heat transfer equation. The effects of the location and size of fire source and baffle length on velocity and temperature distributions, species mass fraction and flame location are analyzed. As the results of this study, it is found that the case when the fire source is located at the vertical wall is more dangerous than at the bottom wall in view of the combustion products and flame location. It is also found that the radiation effect cannot be neglected in analyzing the building in fire.
박희용,박경우,이주형,Pak, H.Y.,Park, K.W.,Lee, J.H. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.3
The interaction of laminar mixed convection and surface radiation in a two-dimensional channel with an array of rectangular blocks is analyzed numerically. Three blocks are maintained at high temperature and the other bottom and top horizontal walls are insulated. Discrete ordinate method(DOM) is introduced to analyze the radiative heat transfer. The effects of the variations of Reynolds number and channel specifications on the heat transfer characteristics are investigated. The average Nusselt numbers along the block surfaces are correlated and presented in terms of Reynolds number and dimensionless geometric parameters such as the block spacing, height and channel spacing. For the conditions considered in this study, average Nusselt numbers along the block surfaces are strongly influenced by the channel spacing and Reynolds number but weakly influenced by the block spacing and block height.
내부핀이 부착된 원형관유동에서의 열전달특성에 관한 수치적연구
박희용,박경우,최문석,Pak, H.Y.,Park, K.W.,Choi, M.S. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.2
Steady, laminar, forced convection flow and heat transfer in the entrance region of an internally finned circular duct with a finite thermal conductivity has been analyzed numerically. The problem under investigation is a three-dimensional boundary layer problem, and is solved by employing a marching-type procedure which involves solution of a series of 2-dimensional elliptic problems in the cross-stream plane. Two types of inlet hydrodynamic conditions are considered : (a) uniform velocity flow and (b) fully developed flow. From the above inlet conditions, the effects of the fin height(h), fin number(N) and conductivity ratio($k_r$) on the flow and thermal characteristics are investigated. The numerical results show that the height and number of fins, and ratio of the solid to fluid thermal conductivity have pronounced effect on the solution. Considering pressure drop, optimized dimensionless fin height is 0.4.
R-12, R-134a 및 R-22를 사용한 무급유식 스크롤압축기의 성능 비교
박희용,박경우,박용일,Pak, H.Y.,Park, K.W.,Park, Y.I. 대한설비공학회 1993 설비공학 논문집 Vol.5 No.4
In this study, a performance comparison of scroll compressor for various refrigerants(CFC-12, HCFC-22 and HFC-134a) has been numerically carried out. The thermodynamic properties have been calculated by using the recent experimental equations and the performance has been investigated qualitatively at the same geometric specifications and operating conditions of scroll compressor. The results are as follows; HFC-134a has the highest compression ratio of 5.40. The mass flow rate of HCFC-22, which affects the cooling capacity of refrigerant system, is higher than that of other refrigerants. HFC-134a has the highest adiabatic efficiency in comparison with CFC-12 and HCFC-22.
CFC-대체냉매와 스크롤압축기를 사용한 냉동시스템 성능해석
박희용,박경우,Pak, H.Y.,Park, K.W. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.3
A performance analysis of refrigeration system using the HFC-134a and scroll compressor is performed numerically. The refrigeration system mainly consists of various standard components such as heat exchanger, compressor, and expansion device. The model for heat exchanger performance is based on a tube-by-tube method which is analyzed separately by considering the cross-flow heat transfer with the outdoor air flow and pressure drop. Compressor is used the scroll-type compressor which has many merits such as high efficiency, low noise and vibration, and small in size. Short-tube is included as an expansion device. Vapour and liquid line are also considered for the performance analysis of refrigeration system. Using the modeling of various components of refrigeration system, a performance comparison of CFC-12 and HFC-134a is performed numerically for the various outdoor air temperature and various values of short-tube diameter. As the results of this study, the refrigeration system performance decreases as the outdoor air temperature increases. And the optimum short-tube diameter based on COP is 1.37mm for this system.