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INTERFACIAL HEAT TRANSFER IN MICROGRAVITY

机译：微重力的界面热传递

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The knowledge of interfacial heat and mass transfer is important for many technical applications, as well for the understanding of fundamental processes in our environment, and everywhere where two phases are in direct contact under non equilibrium conditions. Our interest concentrates especially on liquid-vapor systems in which we have to consider evaporation and condensation at the interface in all two phase systems. In technical applications the interfa-cial heat transfer is mostly treated global from one bulk phase to the other; however, often it is necessary and for the basic physical understanding desirable, to determine the different transport mechanisms separately and in detail. Interesting, and almost unknown, is the mass exchange directly at the interface itself which is coupled with the heat transfer by the evaporation or condensation energy. The kinetics of this phase transition process is not well understood. According to the kinetic theory of Hertz and Knudsen only a small temperature difference at the interface is necessary that mass exchange occurs. This theory is often difficult to apply, because it is based on ideal assumptions and not reliable for real systems. Therefore, accommodation coefficients are introduced to bridge the gap between the ideal and the real systems. These accommodation coefficients must be determined experimentally up to day; they differ by orders of magnitude. A reason for that may be found in the experimental difficulties like non uniform temperature at the interface, not well defined boundary conditions in the experimental evaluation etc. In this paper the problem of interfacial heat transfer is discussed and an experiment described which is performed in microgravity environment. With it more reliable data for the evaporation and condensation coefficients are expected; data necessary for application, and data-to check modern molecular dynamic calculations.
机译：对界面热量和传质的知识对于许多技术应用来说都很重要，也很重要，以及了解我们环境中的基本过程，以及在非平衡条件下两个阶段都直接接触的任何地方。我们的利益尤其集中在液体 - 蒸气系统上，其中我们必须考虑所有两种相位系统的界面处的蒸发和冷凝。在技​​术应用中，Interfa-Cial传热主要从一个散装相到另一个散装阶段处理;然而，通常需要和基本的物理理解是必要的，并且可以单独确定不同的传输机制。有趣，且差不多是未知的，是直接在界面本身处的质量交换，其与蒸发或冷凝能的热传递联接。该阶段过渡过程的动力学尚不清楚。根据赫兹的动力学理论，Knudsen仅在界面处只有较小的温差，必须发生爆发。这种理论往往难以申请，因为它是基于理想的假设，而不是真实系统的可靠性。因此，引入了容纳系数以弥合理想和真实系统之间的差距。这些容纳系数必须在实验上确定;它们的级别不同。在界面处的非均匀温度的实验困难中可以发现该原因，在实验评估中的实验评估中的边界条件不良好地定义。在本文中讨论了界面传热的问题，并在微匍匐中进行了实验环境。随着预期蒸发和冷凝系数的更可靠数据;应用程序所需的数据以及数据 - 检查现代分子动态计算。

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