Investigation of Thin Film Evaporation in Close Loop Thermosyphon

• Main Authors: Sheng-Cian Chen, 陳聖謙
• Other Authors: 陳希立
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/62951881375248869319

碩士 === 國立臺灣大學 === 機械工程學研究所 === 94 === With the growth of electronics manufacturing, electronic components become more powerful and the size of them tends to be smaller. It induces the challenge in thermal solution, and several kinds of electronic cooling methods are applied to conquer the thermal dissipation problem. In recent years, the applications of boiling-condensation heat transfer mechanism are widely used for the heat dissipation problem, and closed loop thermosyphon is one of them. It is found in a previous study that thin film evaporation, which has a great heat transfer capacity, occurs in the evaporator of closed loop thermosyphon system while a low fill ratio of working fluid and a sintered evaporation surface are adopted. The presented study focuses on the occuring mechanicsm of thin film evaporation with sintered surface for evaporator design. This paper establishes a set of experimental methods for investigation and analysis of the loop thermosyphon system. The influences of heating power, fill ratio, tilt angle of sintered surface, and thickness of sintered structure to heat transfer performance of evaporator are under concern. The results show that the evaporator has four heat transfer patterns in different operating condition: (a)dry out, (b)thin film evaporation, (c)transition and (d)boiling. It is apparent that the heat transfer performance of thin film evaporation is better than boiling. By comparing different flow patterns, it shows that the sintered surface of non-horizontal type has larger thin film evaporation region than horizontal type and that thicker sintered structure is helpful to enlarge thin film evaporation region.