Kang-Youl Bae

Study on the Thermal and Flow Characteristics on the Periodically Arranged Semi-Circular Ribs in a Rectangular Channel

The article investigates turbulent flow characteristics and heat transfer enhancement on periodically arranged semicircular ribs fitted in a rectangular channel. The channel was fabricated as the aspect ratio of AR 5, rib height to hydraulic diameter ratio was 0.07, and rib height to channel height ratio was set as e/H 0.117 for various rib pitch to rib height ratios between 8 and 14. In order to predict realistic phenomena of heat transfer and flow characteristics near the wall, shear stress transport k-ω turbulence and v2-f turbulence models were chosen. The results of numerical analysis show turbulent flow characteristics, heat transfer enhancement, and the effect of friction as observed experimentally. The results shows that turbulent kinetic energy (k) is closely related to diffusion of recirculation flow, and results from v2-f turbulence model simulation are in agreement with experimental values.

Convective Heat Transfer in Ventilated Space with Various Partitions

The laminar convective heat transfer in ventilated space with various horizontal partitions was studied numerically and experimentally. For the numerical study, the governing equations were solved by using a finite volume method for various numbers Re, Gr, Pr and partition numbers. The experimental study was conducted by using a holographic interferometer. The isotherms and velocity vectors have been presented for various parameters. As the number and length of partition ncreased, convective heat transfer decreased. Based on the numerical data, correlation equations were obtained for the mean Nusselt number in term of Gr/Re2. In the region ofGr/Re2<-1, the mean Nusselt number was small, but in the region ofGr/Re2>1, the mean Nusselt number was constant.

Study on natural convection in a rectangular enclosure with a heating source

The natural convective heat transfer in a rectangular enclosure with a heating source has been studied by experiment and numerical analysis. The governing equations were solved by a finite volume method, a SIMPLE algorithm was adopted to solve a pressure term. The parameters for the numerical study are positions and surface temperatures of a heating source i.e., Y/H=0.25, 0.5, 0.75 and 11°C≦ΔT≦59°C. The results of isotherms and velocity vectors have been represented, and the numerical results showed a good agreement with experimental values. Based on the numerical results, the mean Nusselt number of the rectangular enclosure wall could be expressed as a function of Grashof number.

The Effect on the Heat Transfer According to Geometric Variation of Air-Fin Vaporizer with at Cryogenic Temperature

At present time, LNG demand of the world is increasing and the piping line for NG transportation has been already installed in Korea. The air fm vaporizer is, however, required because of the transportation for remotely local areas. This paper numerically investigates on the heat transfer characteristics of relevant geometric variations of air-fin vaporizer which is heated by air not by sea water. This vaporizer must be designed in consideration of both efficiency and economics because air is relatively a little heat source. In this study, the pipe and the longitudinal fins are fundamental geometric considerations. Main parameters of geometry are the number, the thickness, and the length of the fins. Finally, the results of heat transfer effects are investigated with the characteristics of each parameter variation.