Numerical Simulation of Heat and Fluid Flow Phenomena during Melting Process in a Rectangular Enclosure with a Moving Wall

• Main Authors: Tzu-Cheng Lin, 林子成
• Other Authors: Ching-Jenq Ho
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/21506705058632233375

碩士 === 國立成功大學 === 機械工程學系 === 89 === A numerical study for melting process of PCM (phase change material) in a rectangular enclosure with a movable upper wall is presented. The vertical sidewalls of the enclosure are isothermally heated, while the horizontal sidewalls are assumed adiabatic. The upper wall of the enclosure is allowed to move freely due to the volumetric change associated with density change of PCM. Simulation results reveal that at low Rayleigh numbers the melting rate of PCM in the enclosure is slow, and the velocity of movable upper wall tends to decrease stably with time. At high Rayleigh numbers, the melting rate increases distinctly. During the intermediate stage of melting process, the velocity of movable upper wall becomes unstable, and oscillation is detected at the center of fluid field in liquid zone. In addition, the melting process neglecting density change associated with phase change is considered. The results reveal that the development of natural convection in the enclosure is initially slower in comparison with that with movable upper wall, but the flow field is stronger in the enclosure with stationary upper wall during the intermediate stage of the melting process.