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수평관 내 이산화탄소의 냉각 열전달 및 압력강하 특성에 관한 연구
김대희(Kim Dae-Hui),손창효(Son Chang-Hyo),김영률(Kim Young-Lyoul),오후규(Oh Hoo-Kyu) 한국마린엔지니어링학회 2004 한국마린엔지니어링학회 학술대회 논문집 Vol.2004 No.-
This paper presents the heat transfer and pressure drop characteristics during cooling process of carbon dioxide in a horizontal tube. The experiments were conducted using a counter now heat exchanger without oil in refrigerant loop. The main components of the apparatus consist of a receiver, a variable speed pump, a mass flowmeter, a pre-heater, a gas cooler(test section) and an isothermal tank. The test section is a tube in tube type heat exchanger with refrigerant flowing in the inner tube and water no wing in the annulus. It was made of a stainless steel tube with the inner diameter of 7.75 [mm], the outer diameter of 9.53 [mm] and length of 6000 [mm]. The refrigerant mass nuxes were 200-400 [kg/㎡s] and the average pressure varied from 7.5 [MPa] to 10.0 [MPa]. The main results were summarized as follows: The heat transfer coefficient of supercritical CO₂ increases in decrease of the gas cooler pressure. And the heat transfer coefficient increases with respect to the increase of the refrigerant mass flux. Among some correlations proposed in a transcritical region, Bringer-Smith's correlation has some analogy with experimental results. The pressure drop decreases in increase of the gas cooler pressure and increases with respect to increase the refrigerant mass flux.
관 배열에 따른 삼중효용 흡수식 냉동기용 배기가스 열교환기 최적 설계
김성민(Seong Min Kim),김영률(Young Lyoul Kim),김선창(Seon Chang Kim) 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.6
In this paper, the design optimization of exhaust gas heat exchanger for triple effect absorption chiller was performed. The fractional factorial DOE was used in screening phase to select the main design factor. ST and No. of rows were selected as a main design factor. next, The main design factors were to optimize the exhaust gas heat exchanger using the response surface method DOE.
태양열과 가스를 이용한 하이브리드 흡수식 냉온수기의 성능특성
권오경(Oh Kyung Kwon),김영률(Young Lyoul Kim),차동안(Dong An Cha),김효상(Hyo Sang Kim) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.6
In this paper, the performance evaluation for a solar/gas hybrid absorption system using LiBr-H2O is numerically and experimentally studied. In order to use solar energy more effectively, a new type of solar/gas driving hybrid absorption system is designed. This system operates in solar energy without gas consumption when solar radiation is high and in gas energy when solar radiation is low. So the objective of this paper is to investigate the cooling characteristics of a hybrid absorption system using solar and gas energy. In this system, three different modes are conducted: single, double and hybrid operation mode. A prototype is designed and made in the present study. The results show that the COP in the hybrid mode can reach 1.53, increasing of 28.6% as compared with the COP 1.19 in the double effect mode.
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.
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.
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.