Sub-atmospheric boiling heat transfer and thermal performance of two-phase loop thermosyphon
Sub-atmospheric boiling heat transfer and thermal performance of two-phase loop thermosyphon
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DOI：
10.1016/j.expthermflusci.2012.01.017
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发表时间：
2012-05
影响因子：
3.2
通讯作者：
S. Chang;D. Lo;K. Chiang;Ching Yuan Lin
中科院分区：
文献类型：
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作者：
S. Chang;D. Lo;K. Chiang;Ching Yuan Lin
通过可视化实验，研究了两相回路热虹吸管（TPLT）的沸腾传热和不稳定性、热力循环、组分热阻和总热阻。在水作为工作流体的情况下，在电子冷却应用的典型温度范围下，该TPLT中的相变压力是低于大气压的。随着亚大气压下沸腾热流密度的增加，沸腾结构从间歇泰勒泡向连续泡状流的转变与正压下的转变路线相反，并触发了两种不同类型的沸腾不稳定性。一组选定的结果说明了沸腾加热器功率（Q）和冷凝器热阻（Rth，con）对每个热性能的相互依赖的影响。三套传热关联式用于确定池沸腾，间歇和蒸发器的蒸汽区域的沸腾传热系数沿着与两套经验关联式，允许单独的和相互依赖的Q和Rth的评估，对测试TPLT的总热阻和蒸发器压力的影响。这些经验关联式的适用条件大大扩展了公开文献中可用的压力范围的下限，这增加了在低于大气压下操作的两相传热装置的设计能力。
This experimental study investigates the thermal performances of a two phase loop thermosyphon (TPLT) by examining the boiling heat transfer and instabilities, the thermodynamic cycles and the constituent and overall thermal resistances with the aid of boiling flow structures collected from visualization tests. With water as the working fluid, the phase-change pressures in this TPLT at the temperature range typical for electronic cooling applications are sub-atmospheric. Followed by increasing the boiling heat flux at sub-atmospheric pressures, the transition of boiling structures from intermittent Taylor bubble to continuous bubbly flows reverses the transition route at positive pressures and triggers two different types of boiling instabilities. A set of selected results illustrates the interdependent impacts of boiling heater power (Q) and condenser thermal resistance (Rth,con) on each thermal property investigated. Three sets of heat transfer correlations for determining the boiling heat transfer coefficients over pool-boiling, intermittent and vapor regions of the evaporator along with two sets of empirical correlations that permit the evaluation of individual and interdependent Q and Rth,coneffects on overall thermal resistances and evaporator pressures of the tested TPLT are generated. The applicable conditions for these empirical correlations considerably extend the lower end of pressure range available in the open literature, which add design capabilities for two-phase heat transfer devices operating at sub-atmospheric pressures.