http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
노즐-디퓨저 내에서의 저 Reynolds 수 유동특성 해석
송귀은(Gwi-Eun Song),이준식(Joon-Sik Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
An investigation of low Reynolds number flow in nozzles and diffusers which are widely used in the valveless micropump is presented. Flow characteristics in the nozzle and diffuser are explained in view of viscous effect and flow oscillation induced by pumping membrane. These calculation results show that the rectification property of valveless micropump is due to a flow separation in the diffuser and the separation is largely originated from the flow oscillation. Under the assumptions of steady flow velocity profile and flow separation in the diffuser, simplified analytical models are provided to see the dependency of rectification on the micropump geometry. Geometric parameters of channel length, nozzle throat, chamber size, and converging/diverging angle are depicted through the analytical models in low Reynolds number flow, and the prediction and experimental results are compared. This theoretical study can be used to determine the optimum geometry of valveless micropump.
송귀은(Gwi-Eun Song),이대영(Dae-Young Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Optimal design of an air-to-liquid finned plate heat exchanger is considered theoretically in this study. Based on existing correlations for the pressure loss and the heat transfer in channel flows, the optimal configuration of the plate heat exchanger including the optimal plate pitch and the optimal fin pitch is obtained to maximize the heat transfer within the limit of the pressure drop for a given flow depth of the plate heat exchanger. It is known that the heat transfer performance can be maintained exactly the same if the geometric parameters such as the plate thickness, plate pitch, fin thickness, and fin pitch are reduced proportional to the square root of the flow depth as long as the flow keeps laminar within the heat exchangers. But the limitation of available fabrication material thickness, fin thickness and plate thickness may not be chosen properly according to the square root dependency. Changed optimal configuration to obtain compact configuration with shortened flow depth keeping fin and plate thicknesses constant are investigated and heat transfer rate reduction is theoretically derived with proper assumptions.
좌굴과 상변화를 이용한 micro actuator 의 개발 및 해석
송귀은(Song Gwi Eun),김정식(Kim Jeong Sik),김광호(Kim Kwang Ho),이윤표(Lee Yoon Pyo) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
A brand-new micro actuator is introduced in this paper. This device is one of thermo-pneumatic<br/> actuators, and based on two distinct principles of snap-through buckling and phase change. These coupled<br/> phenomena affect each other positively and will outrun the performance of an ordinary thermo-pneumatic<br/> actuator. Our efforts are focused on comprehensive analysis on the driving force of the actuator. For the<br/> analysis, we explain each principle and offer approximated models for the buckling and phase change. The<br/> calculation results from each model are compared to experimental data. The comparison between prediction<br/> from models and data from experiments is within the satisfaction in spite of a lot of approximations.
송귀은(Gwi-Eun Song),이대영(Dae-Young Lee) 대한설비공학회 2006 대한설비공학회 학술발표대회논문집 Vol.2006 No.6
Regenerative evaporative cooling is known as an environment-friendly and energy efficient cooling method. A regenerative evaporative cooler (REC) consisting of dry and wet channels is able to cool down the air stream below the inlet wet-bulb temperature. In the regenerative evaporative cooler, the cooling effect is achieved by redirecting a portion of the air flown out of the dry channel into the wet channel and spraying water onto the redirected air. In this study, a horizontal regenerative cooler is considered. In the horizontal regenerative cooler, the flow direction of evaporating water has a right angle to the flow direction of supply air. This difference was investigated with visualization technique and simplified 2-module performance test was done in a thermo-environment chamber. Optimum design configuration is changed due to the wet channel which are easily fully covered with evaporating water and block the air flow inside the channel. Applying the optimized fin configuration design with the highly wetting surface treatment, a regenerative evaporative cooler was fabricated and tested to identify the cooling performance improvement and operation characteristics. From the experimental results at the intake condition of 32 ℃ and 50 % RH, the supply temperature was measured to be around 23.4 ℃. The cooling effectiveness based on the inlet dewpoint temperature was evaluated 73 % which is almost close to the design expectation.
이병서(Byoung Seo Lee),송귀은(Gwi-Eun Song),이준식(Joon Sik Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
A computational fluid mechanics study is performed on valveless diffuser type micropumps for the purpose of designing the micropumps efficiently and making the mechanism clearly understood. The program developed is validated through the comparison of the pressure losses in conic flows. The steady flow analysis is adapted to some diffuser elements and a micropump to present their flow characteristics and efficiencies. The diffuser elements show maximum efficiency of 1.2 at 20 ml/min. The flow structure observed by the steady analysis is coincident with one of various structures that can be observed in visualization of chamber flows.
확장표면을 적용한 액체식 제습시스템의 성능특성에 관한 연구
장영수(Young-Soo Jang),송귀은(Gwi-Eun Song),이대영(Dae-Young Lee) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
This study presents the new idea of liquid desiccant system with extended surface to reduce the system size. The extended surface is inserted between vertical cooling/ heating tubes to increase the mass transfer area, and the liquid desiccant flows through the tube wall and the extended surface. Mathematical models for heat and mass transfer between liquid desiccant and air stream at tube wall and extended surface are provided. Dimensionless design parameters governing heat and mass transfer phenomena around the tube and the extended surface are identifier, and dimensionless operating parameters depicting system operating condition including flow rate ratio between dehumidification/ regeneration processes, and mass flow rate ratio between air stream and liquid desiccant are explained. The effects of the parameters on system performance are summarized.
이대영(Dae-Young Lee),송귀은(Gwi-Eun Song) 대한설비공학회 2009 설비공학 논문집 Vol.21 No.10
The optimum rotation speed of a desiccant rotor is studied theoretically based on a theoretical solution to the heat and mass transfer processes in the desiccant rotor. A simple correlation equation for the optimum rotation speed is derived to show the effects of various parameters including the thermo-physical properties, the geometric dimension, and the operating condition of the desiccant rotor. The theoretical result is compared with existing experimental data to validate the linearization and simplification included in the solution procedure. Based on the theoretical solution, the effects of major parameters on the optimum rotation speed are studied and the fundamental mechanism of the influences is investigated.
조성호(Sung-Ho Cho),이대영(Dae-Young Lee),조형희(Hyung-Hee Cho),송귀은(Gwi-Eun Song),최재영(Jae-Young Choi) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
This study presents a mathematical model for heat and mass transfer between liquid desiccant and inlet air in liquid desiccant system with extended surface. Numerical analysis programs also calculate moisture removal rate in air stream. In same condition, the experimental results are compared with numerical results and experimental results to change inlet air volume flow rate and cooling water temperature.
확장 표면을 적용한 액체식 제습기의 성능에 대한 실험적 연구
조성호(Sung-Ho Cho),최재영(Jae Young Choi),이대영(Dae-Young Lee),리광훈(Gwang Hoon Rhee),송귀은(Gwi-Eun Song) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
This study presents a new idea of liquid desiccant system with extended surface to reduce the system size. The extended surface is inserted between vertical cooling/ heating tubes to increase the mass transfer area, and the liquid desiccant flows through the tube wall and the extended surface. The effect of varying air and solution inlet conditions, flow rates and fin pitch on the system performance was studied with experimental method. As a result, the effect of extended surface on the system performance improved 28% at fin pitch 4㎜.