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흡수식 적용을 위한 이성분 나노유체의 분산안정성에 관한 실험적 연구
정청우(Chung Woo Jung),김진경(Jin-Kyeong Kim),강용태(Yong Tae Kang) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
When a little amount of certain nanosized particles is added into a basefluid, the thermal conductivity of that mixture increases greatly. Such mixtures are named nanofluids where nano-particles should be distributed stably and uniformly so the distribution stability of nanoparticles in nanofluids is one of the most important factors for nanofluid application. To predict the distribution stability of solid-liquid mixture, the zeta potential which represents the degree of the surface potential dispersed in fluid, is generally considered as a distribution stability criterion. Moreover, zeta potential is applied to the production of nano-particles, the sedimentation of heavy metals, and the analysis of the property of colloidal system. This study is carried out to apply the concept of nanofluid to the absorption system. Therefore, binary nanofluids in which binary mixtures are applied as the basefluids are considered as working fluids. The kind and the concentration of nanoparticles, and the concentration of ammonia are considered as the key parameters. The objectives of this paper are to visualize the dispersed status of particles in binary nanofluids and to find the effect of key parameters on the distribution stability in the ammonia absorption system.
역삼투압방식의 냉/온정수기 퇴수를 이용한 수랭식 응축기와 기존의 공랭식 응축기 성능비교
이재원(Jae Won Lee),정청우(Chung Woo Jung),김성수(Sung Soo Kim),강용태(Yong Tae Kang) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
The reverse osmosis type water purifier is able to purify only about 20~40% of the tap water or underground water, and the rest is discarded. Generally, the cooling system of a small domestic cold & hot water purifier uses an air cooled type condenser. One disadvantage of this system is that the cooling capacity depends on the ambient conditions, therefore it needs a big size of heat exchangers. However, it is possible to solve this problem by reusing the drain water in the water cooled type condenser. The power consumption rate of the cooling system with the air cooled type condenser is estimated as 66.2W, while that with the a water cooled type condenser is estimated as 54.2W. Therefore, the water cooled type condenser reusing drain water is recommended to reduce the power consumption in the compressor.
압축/흡수 하이브리드 히트 펌프 시스템의 암모니아-물 플레이트 흡수기에 대한 실험 및 수치 시뮬레이션 연구
안승선(Seung Sun An),정청우(Chung Woo Jung),김민성(Min Sung Kim),박성룡(Seong Ryong Park),강용태(Yong Tae Kang) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.6
This research conducts an experiment for a hybrid heat pump system, using ammonia / water as a working fluid, to obtain a high-temperature water. The hybrid heat pump system uses a low temperature heat source of about 50℃ from industrial waste heat. This hybrid system is the combination of a compression cycle and an absorption cycle, to improve the efficiency of the heat pump. The system is consists of absorber, desorber, solution heat exchanger, oil heat exchanger, rectifier, compressor and a solution pump. Additionally, parametric analysis is carried out for key parameters such as the capacity of the absorber, the internal pressure change and the ammonia solution concentration. Finally, the experimental and simulation results are compared.
이성분 나노유체 (NH₃/H₂O + 나노입자)의 열전달 및 흡수성능 촉진실험
이진기(Jin Ki Lee),정청우(Chung Woo Jung),강용태(Yong Tae Kang) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.9
The objectives of this paper are to examine the effect of nano-particles on the pool type absorption heat transfer enhancement and to find the optimal conditions to design a highly effective compact absorber for ammonia/water absorption system. The effect of Al₂O₃ nano-particles and carbon nanotube(CNT) on the absorption performance is studied experimentally. The experimental ranges of the key parameters are 20% of ammonia concentration, 0~0.08 vol% (volume fraction) of CNT particles, and 0~0.06 vol% of Al₂O₃ nano-particles. For the ammonia/water nanofluids, the heat transfer rate and absorption rate with 0.02 vol% Al2O3 nano-particles were found to be 29% and 18% higher than those without nano-particles, respectively. It is recommended that the concentration of 0.02 vol% of Al₂O₃ nano-particles be the best candidate for ammonia/water absorption performance enhancement.
Zeta-potential을 이용한 이성분 나노유체의 분산안정도 측정
이강일(Kang Il Lee),정청우(Chung Woo Jung),김현준(Hyun Jun Kim),정진희(Jinhee Joeng),강용태(Yong Tae Kang) 대한설비공학회 2006 대한설비공학회 학술발표대회논문집 Vol.2006 No.6
This study investigates the distribution stability of binary nanofluids where binary mixtures such as NH₃/H₂O and H₂O/LiBr solution are used as a base fluid. When a little amount of certain nanosized particles is added into a basefluid, the thermal conductivity of that mixture increases greatly. Such mixtures are named ""nanofluids"" where nano-particles should be distributed stably and uniformly so the distribution stability of nanoparticles in nanofluids is one of the most important factors for nanofluid application. Therefore, binary nanofluids in which binary mixtures are applied as the basefluids are considered as working fluids. The kind and the concentration of nanoparticles, and the concentration of ammonia are considered as the key parameters. The objectives of this paper are to visualize the dispersed status of particles in binary nanofluids and to find the effect of key parameters on the distribution stability in the ammonia absorption system.