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수직원관형 흡수기의 흡수과정에 미치는 비흡수가스의 영향
허기준,정은수,정시영 대한설비공학회 1998 설비공학 논문집 Vol.10 No.4
Effect of a non-absorbable gas on the absorption process in a vertical tube absorber was investigated numerically. The water vapor mined with air as the non-absorbable gas is absorbed into LiBr/water solution film. The flow is assumed to be laminar and fully developed in both liquid and gas phases. The diffusion and energy equations were solved in both phases to give the temperature and concentrations, from which heat and mass fluxes were determined. It was shown that the local absorption rate decreases as the mass fraction of air in water vapor increases. The vapor pressure of water at the liquid-vapor interface reduces significantly since the non-absorbable gas is accumulated near the interface. The effect of non-absorbable gases on absorption rate becomes larger as the mass flow rate of the vapor decreases. For small amount of non-absorbable gases the total absorption rate of water vapor increases as the mass flow rate of the vapor decreases. Total absorption rate increases as the mass flow rate of the vapor increases for large concentration of non-absorbables at the inlet of an absorber.
냉각수의 영향을 고려한 수직원관형 흡수기의 흡수과정 해석
鄭恩洙,許基俊 弘益大學校 科學技術硏究所 1999 科學技術硏究論文集 Vol.10 No.1
Absorption process of water vapor into LiBr/water solution within a vertical tube absorber was investigated numerically. A film of LiBr/water solution flows down inside a vertical tube and the water vapor mixed with air flows concurrently with the liquid film. The coolant outside the tube flows counter-currently with the LiBr/water solution. The water vapor mixed with air as the non-absorbable gas is absorbed into LiBr/water solution film. The flow is assumed to be laminar and fully developed in both liquid and gas phases. The diffusion and energy equations were solved in both phases to give the temperature and concentration, from which heat and mass fluxes were determined. The coolant temperature and the wall temperature are obtained from the energy balance of the coolant. It was shown that the local absorption rate decreases as the mass fraction of air in the water vapor increases. The vapor pressure of water at the liquid-vapor interface reduces significantly since the non-absorbable gas is accumulated near the interface. Total absorption rate increases as the coolant temperature decreases since the rate near the liquid inlet increases as the coolant flow rate increases, but that near the liquid outlet decreases since the water vapor pressure decreases due to the larger absorption rate near the liquid inlet.
소결된 유리 구체를 다공성 물질로 사용한 마이크로 CPL 설계의 새로운 접근에 관한 연구
허기준(K. J. Hur),권오명(O. M. Kwon),박승호(S. H. Park),정은수(E. S. Jeong),유재륜(J. R. Yoo),강환국(H. K. Kang),이준식(J. S. Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
A high performance heat spreader is needed to prevent local heating which is expected to break a chip. A micro CPL is highlighted for a method to improve the existing heat spreader. However, bubble generation between evaporator and liquid line must be kept away to use a micro CPL as a heat spreader. In order to minimize this problem, porous media shall be inserted between evaporator and liquid line. Pore radius of porous media were estimated by capillary pumping limit analysis and porous media were manufactured by inserting micro size glass beads into a jig and sintering at high temperature in a vacuum chamber. It is expected that a micro CPL as a heat spreader is redesigned to minimize bubble generation.
암모니아/물 흡수식 열펌프의 흡수기의 흡수과정에 대한 수치적 해석
鄭恩洙,許其俊 弘益大學校 科學技術硏究所 2000 科學技術硏究論文集 Vol.11 No.-
A numerical model which simulates the simultaneous heat and mass transfer within a vertical tube absorber of an ammonia/water absorption heat pump was developed. The flow of the liquid film was assumed to be laminar. The film thickness and the velocity distribution of the liquid film were obtained by matching the shear stress at the liquid-vapor interface. A modified Colburn-Drew analysis was used for the vapor phase to determine the heat and mass fluxes at the liquid-vapor interface. The model was used to investigate the effects of the vapor mass flow rate, the diameter and the length of the absorber, and the mass fractions of the vapor and the liquid at inlet on the absorption rates of water and ammonia. It was shown that both ammonia absorption rate and water desorption rate increase near the inlet of the absorber as the mass flow rate of the vapor increases. Absorption rate increases as the diameter of the absorber decreases since heat and mass transfer coefficients increase as the vapor flow rate increases. The effects of the ammonia mass fractions of liquid and vapor on absorption rate were negligible.
이병진,허기준,신재학,박세계,박정훈,김우진,정재희,최동윤 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
최근 SARS-CoV-2 와 같은 대기 중 부유미생물에 의한 감염 및 피해 사례가 증가함에 따라 피해 저감을 위한 항균 기술에 대한 연구가 증가하고 있다. 특히, 가시광반응 소재는 넓은 파장 범위의 광원을 사용한다는 이점으로 주목받고 있으나, 약한 수분안정성으로 인한 적용의 많은 제한이 있다. 따라서, 본 연구에서는 수분안정성 개선을 위한 광 투명성 Al-Si 무기 졸과 가시광반응 유기염료인 crystal violet 의 복합 코팅 용액을 폴리에스터 필름에 코팅하여 높은 항균성과 수분안정성을 갖는 항균 필름을 소개한다. 제조된 필름의 화학적 구조를 분석하였으며, 무기 졸의 농도에 따른 유기염료의 수분안정성은 세척 및 흡광도 분석을 통해 검증하였다. 항균 필름은 광 노출 4 시간 후 ~99.9%의 항균 효율을 나타내었으며, 유기염료와 무기 졸의 비율에 따른 항균 활성도 및 두께에 따른 항균 효율을 확인하기 위하여 무기 졸의 농도와 코팅 두께를 바꾸어 필름의 항균성능을 측정하였다.
도심 내 버스정류장 부근의 에어로졸 입자 크기 및 형상 관찰
정상빈,허기준,신창훈,조원경,이병욱,Jeong, Sang Bin,Heo, Ki Joon,Sin, Chang Hoon,Zhao, YuanQing,Lee, Byung Uk 한국입자에어로졸학회 2016 Particle and Aerosol Research Vol.12 No.4
People in metropolitan cities can be exposed to particulate air pollutants at public transportation systems such as bus stops. In this study, we sampled aerosol particles with an impactor at a bus stop. We analyzed the shapes of these particles with an optical microscope. It was estimated that fibers, silicons, byproducts of combustion, and pollens existed in the air environments at the bus stop with analysis of shapes of sampled particles.