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Combined Convection and Radiation in a Tube with Circumferential Fins and Circular Disks
Namjin Kim,Jaeyong Lee,Taebeom Seo,Chongbo Kim 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.12
Combined convection and radiation heat transfer in a circular tube with circumferential fins and circular disks is investigated for various operating conditions. Using a finite volume technique for steady laminar flow, the governing equations are solved in order to study the flow and temperature fields. The P-1 approximation and the weighted sum of gray gases model (WSGGM) are used for solving the radiation transport equation. The results show that the total Nusselt number of combined convection and radiation is higher than that of pure convection. If the temperatures of the combustion gas and the wall in a tube are high, radiation becomes dominant. Therefore, it is necessary to evaluate the effect of radiation on the total heat transfer.
Dissolution Behavior and Hydrate Effect on CO₂Ocean Sequestration
Namjin Kim,Chongbo Kim 대한기계학회 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.5
CO₂ocean sequestration is one of the promising options to reduce CO₂ concentration in the atmosphere because the ocean has vast capacity for CO₂ absorption. Therefore. in the present investigation. calculations for solubility and dissolution behavior of liquid CO₂ droplets released at 1000 m and 1500 m deep in the ocean from a moving ship and a fixed pipeline have been carried out in order 10 estimate the CO₂ dissolution characteristics in the ocean. The results show liquid CO₂ becomes CO₂ bubble at around 500 m in depth. and the solubility of seawater is about 5% less than of pure water. Also. it is shown that the injection of liquid CO₂ from a moving ship is a more effective method for dissolution than from a fixed pipeline. and the presence of hydrate on liquid CO₂ acts as a resistant layer in dissolving liquid CO₂.
Development of a Microelectronic Cooling Device using a Micro Capillary Pumped Loop
JaeYong Lee,ChongBo Kim,Hayong Yun,KyungIl Cho,HyeJung Cho,InSeob Song 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3
A capillary pumped loop (CPL), which is a microfabricated capillary pressure driven heat exchange cycle, is proposed as an alternative means of microelectronics cooling. In order to investigate the behavior of the Micro-CPL system, a lumped parameter model has been newly developed. The system simulation has been conducted for the capillary evaporator, condenser and two connecting valves. Specifically, a prototype micro-CPL with 20 W/㎠ cooling capacity has been modeled and tested. From the result, the prototype has been operated successfully under the heat flux with the heat junction temperature below 100℃. Also the system simulation model has well captured the overall trend of the experimental test data. Finally, the feasibility of Micro-CPL for high power chip cooling and the usefulness of the cycle simulation model for system design have been shown from this study.