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김선창,오명도,이재헌,Kim, Seon-Chang,O, Myeong-Do,Lee, Jae-Heon 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.10
Numerical analyses have been performed to estimate the absorption heat and mass transfer coefficients in absorption process of the LiBr aqueous solution and the total heat and mass transfer rates in a vertical tube absorber which is coolING ed by air. Axisymmetric cylindrical coordinate system was adopted to model the circular tube and the transport equations were solved by the finite volume method. Absorption behaviors of heat and mass transfer were analyzed through falling film of the LiBr aqueous solution contacted by water vapor in tube. Effects of film Reynolds number on heat and mass transfer coefficients have been also investigated. Especially, effects of tube diameter have been considered to observe the total heat and mass transfer rates through falling film along the tube. Based on the analysis it has been found that the total mass transfer rate increases rapidly in a region with low film Reynolds number(10 ~ 40) as the film Reynolds number increases, while decreases beyond that region. The total heat and mass transfer rates increase with increasing the tube diameter.
고발열 CPU 냉각용 증기 압축식 냉각 시스템의 증발기 최적화
김선창(Seon-Chang Kim),전동순(Dong-Soon Jeon),김영률(Young-Lyoul Kim) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.4
This paper presents the optimization process of evaporator for a vapor compression cooling system for high heat flux CPU. The CPU thermal capacity was given by 300W. Evaporating temperature and mass flow rate were 18℃ and 0.00182㎏/s respectively. R134a was used as a working fluid. Channel width(CW) and height(CH) were selected as design factors. And thermal resistance, surface temperature of CPU, degree of superheat, and pressure drop were taken as objective responses. Fractional factorial DOE was used in screening phase and RSM(Response Surface Method) was used in optimization phase. As a result, CW of 2.5㎜, CH of 2.5㎜, and CL of 484㎜ were taken as an optimum geometry. Surface temperature of CPU and thermal resistance were 33℃ and 0.0502℃/W respectively. Thermal resistance of evaporator designed in this study was significantly lower than that of other cooling systems such as water cooling system and thermosyphon system. It was found that the evaporator considered in this work can be a excellent candidate for a high heat flux CPU cooling system.
김선창(Seon-Chang Kim),김영률(Young-Lyoul Kim),이상재(Sang-Jae Lee),전동순(Dong-Soon Jeon),최장현(Jaug-Hyeon Choi),권혁민(Hyeok-Min Kwon),이창준(Chang-Jun Lee) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
This paper presents the optimization process of liquid desiccant cooling cycle using LiCl aqueous solution as a working fluid. Operating conditions and design factors for heat exchangers were optimized by response surface method. As a result, we obtained the 7.297 ㎾ of cooling capacity and 0.788 of COP at optimized condition. Effect of dT<SUB>hw</SUB> on system performances was also examined. As dT<SUB>hw</SUB> increases, the cooling capacity increases and COP decreases.
난방모드 시 CO₂ 지열히트펌프의 내부열교환기에 대한 운전특성
김선창(Seon-Chang Kim),김영률(Young-Lyoul Kim),김재덕(Jae-Duck Kim),이상재(Sang-Jae Lee) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
This paper presents operating characteristics of internal heat exchanger(IHX) for CO₂ geothermal heat pump in the heating mode. Mass flow rate of CO₂, inlet temperatures of CO₂ at high and low pressure side were selected as main effect factors by using fractional factorial DOE(Design of Experiments). And RSM(Response Surface Method) was used in optimization phase. The results show that heat transfer rate of IHX increases when either inlet temperature of low pressure side decreases or inlet temperature of high pressure side increases. Effectiveness of IHX increases with increasing of inlet temperature of either high pressure side or low pressure side. Finally, performance contour map was provided over the operation ranges of the main design factors.
160℃ 증기 생산을 위한 고온 히트펌프 사이클 최적 설계
김진만(Jin Man Kim),김선창(Seon-Chang Kim),이천규(Cheonkyu Lee),이정길(Jung-Gil Lee) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
In the present study, a study for optimization of a heat pump cycle to produce steam of 160℃ was conducted. To analyze the performance of the system, a two-stage compression cycle with an internal heat exchanger and a flash tank was designed. The temperature of an evaporator, the pressure of a gas cooler, the effectiveness of an internal heat exchanger, and the efficiency of compressors were set as variables, and COP and temperature of the gas cooler according to the conditions were compared through thermodynamic analysis. Finally, an optimization methodology was suggested based on statistical analysis.
자연냉매(R718)를 이용한 응축기 설계 방법론의 제시
김진만(Jin Man Kim),이대규(Daegyu Lee),김선창(Seon-Chang Kim) 대한설비공학회 2020 대한설비공학회 학술발표대회논문집 Vol.2020 No.6
In the present study, a theoretical approach is suggested to design condenser using R718. Unlike a common condensers using R134a, vapor of R718 has an extremely high specific volume (e.g. about 1000 times greater than that of R134a). In this reason, it is difficult to use shell-and-tube type condenser with R718. Therefore, a condenser in the form of a square chamber was devised, and the number of tubes was determined through the design of the single-phase section and the two-phase section. Finally, a Corrugate tube arranged in 10 rows required the smallest number of the tubes to achieve a total heat transfer rate of 415 ㎾.