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RISS 인기검색어
- 검색키워드
- 저자 : Byongjoo Kim (검색결과 9 건)
- 무료
- 기관 내 무료
- 유료
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Non-absorbable Gas Effects on Heat and Mass Transfer in Falling Film Absorption
Byongjoo Kim,Chunkyu Lee 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.4
Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly in the absorption process, its presence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H₂O solution flowing over 6-row horizontal tubes with the water vapor absorption in the presence of non-absorbable gases. The volumetric concentration of non-absorbable gas, air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2% volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41 % reduction in the Sherwood number. Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers, defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.
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Non-absorbable Gas Effects on Heat and Mass Transfer in Falling Film Absorption
Kim, Byongjoo,Lee, Chunkyu The Korean Society of Mechanical Engineers 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.4
Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly In the absorption process. its pretence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H$_2$O solution flow ing over 6-row horizontal tubes with the water vapor absorption in the pretence of non-absorbable gases. The volumetric concentration of non-absorbable gas, air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2% volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41% reduction in the Sherwood number Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers. defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.
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An experimental study on fully developed laminar flow and heat transfer in rectangular microchannels
Elsevier 2016 The International journal of heat and fluid flow Vol.62 No.2
<P><B>Abstract</B></P> <P>An empirical study has been performed to explore the validity of theoretical correlations based on conventional sized channels for predicting fluid flow and heat transfer characteristics in microchannels. The flow resistance and thermal behavior of laminar flow through 10 different rectangular microchannels with hydraulic diameters of 155–580 µm and aspect ratios of 0.25–3.8 at Reynolds numbers ranging from 30 to 2500 were investigated. The single-phase laminar friction factors in the microchannels conformed to the conventional Poiseuille flow theory. The critical Reynolds number increased from 1700 to 2400 with a decrease in the aspect ratio from 1.0 to 0.25. The existence of two heat transfer regimes was verified. At <I>Re</I>< 180, the experimental Nusselt numbers were lower than the theoretical values and increased rapidly with the Reynolds number. The Nusselt numbers began to exceed the theoretical values for <I>Re</I>> 180; however, its rate of increase with the Reynolds number slowed considerably. In this region, the theoretical value of the Nusselt number was assessed to be reasonable as an estimate for rectangular microchannels when the aspect ratio was greater than 1.0.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The laminar fluid flow and heat transfer characteristics in rectangular microchannels were investigated. </LI> <LI> The single-phase laminar friction factors in the microchannels conformed to the conventional Poiseuille flow theory. </LI> <LI> The critical Reynolds number increased from 1700 to 2400 with a decrease in the aspect ratio from 1.0 to 0.25. </LI> <LI> The existence of two heat transfer regimes in the rectangular microchannels was verified. </LI> <LI> For <I>Re</I> > 180, the theoretical value of the Nusselt number was assessed to be reasonable as an estimate for rectangular microchannels when the aspect ratio was greater than 1.0. </LI> </UL> </P>
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金秉宙,白永鎬 弘益大學校 科學技術硏究所 2002 科學技術硏究論文集 Vol.13 No.-
Heat transfer and flow characteristics in narrow rectangular channels with offset-strip fins have been performed experimentally. Single-phase heat transfer coefficient and friction factor were experimentally investigated in 760 mm long and 100 mm wide test sections with 3 mm and 5 mm gap widths. The working fluid was water. The experimental results were compared with the existing correlations. For the rectangular channels with fins, the correlations proposed by Manglik and Bergles were found to be in good agreements with the experimental data in ±15 % of error range.
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Kyseok Kwon,Byongjoo Kim 대한설비공학회 2001 International Journal Of Air-Conditioning and Refr Vol.9 No.2
In the present study, the effects of film Reynolds number (60~200) and volumetric content of non-absorbable gases (0~10%) in water vapor on the absorption process of aqueous LiBr solution were investigated experimentally. The formation of solution film on the horizontal tubes of six rows was observed to be complete for Re>100. Transition film Reynolds number was found to exist above which the Nusselt number and Schmidt number diminishes with solution flow rate. As the concentration of non-absorbable gases increased, mass transfer rate decreased more seriously than heat transfer rate did. The degradation effects of non-absorbable gases seemed to be significant especially when small amount of non-absorbable gases was introduced to the pure water vapor.
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Interdisciplinary and International Collaborative Education for Product Design
Haeseong Jee,Hyunjune Yim,Byongjoo Kim,Alexander Brezing,Manuel Lower (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
The delineated approach provides an educational concept for Collaborative Product Development. It aims at teaching and training skills to accomplish collaborative product development projects as the head of the team as well as a team member. Attention is especially paid to heterogeneous teams of different skills, knowledge, specialization, ambition, location as well as cultural background. As Collaborative Engineering aggravates the definition of structures the proposed approach ceases from the common focus on curriculum-driven education. Instead, the approach incorporates principles of active learning, an approach developed in the early 90s, for exercises. Whilst base knowledge is imparted by means of conventional frontal instruction lectures, the according skills are trained in line with exercises lessons encouraging active participation. A novel exercise concept has been developed to cope with the challenges raised by Collaborative Engineering. This concept stipulates a realistic simulation of a collaborative product development environment. For that purpose, cooperation among the Institute for Engineering Design, RWTH Aachen University, Germany and the Mechanical & System Design Engineering (MSDE) Department as well as the Industrial Design Department, both of Hongik University, Korea has been established. Students from the three departments participate in cooperating project teams to develop a certain product. During the project, the lecturers just assist as consultants, acting if explicitly asked for help by the students. It is intended to let critical situations emerge as under realistic conditions, so the students learn by first hand when and how certain techniques can be applied.
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