Condensation Phenomena in Heat Pipes and Thermosyphons

热管是用很小的热阻输送热量的装置。这种特性是发生在管道两端的相变过程——蒸发和冷凝——的结果。热管有效运行的关键问题是两端之间蒸汽和液体的输送。该方案涉及影响热管运行的三个基本问题：(1)不凝性气体和其他气体或蒸汽种类的分布；(2)放置在热管中的芯结构中蒸汽的冷凝，以促进液体传递；(3)启动、关闭和热负荷变化期间的瞬态效应。拟议的研究包括一系列的建模工作，每个建模工作都包含以前未被解释的现象。为了便于包含这些效应，我们将使用守恒方程的积分形式，而不是更复杂的微分形式。将进行实验来支持和验证分析预测。

Heat pipes are devices which transport heat with only a small thermal resistance. This characteristic is the result of phase change processes--evaporation and condensation--which occur at either end of the pipe. Critical issues in the efficient operation of a heat pipe are the transport of vapor and liquid between the ends. The proposal deals with three fundamental issues which affect the operation of heat pipes: (1) the distribution of noncondensable gases and other gaseous or vapor species, (2) condensation of vapor in the wick structure that is placed in the heat pipe to facilitate liquid transfer, and (3) transient effects during start-up, shut-down, and changes in heat load. The proposed research consists of a succession of modeling efforts, each structured to include previously unaccounted phenomena. To facilitate the inclusion of these effects, the integral forms of the conservation equations will be used rather than the more complex differential forms. Experiments will be performed to support and verify the analytical predictions.