This special issue includes articles that address different aspects of heatand mass-transfer processes at low temperatures for a spectrum of applications in natural sciences and chemical engineering. It is so amazing that in the 20th, and beginning of the 21st, centuries nine Nobel Prizes were awarded for discoveries and research of physical phenomena, for which the work was performed using temperatures below the ambient level. This illustrates that at such temperatures, the “density of knowledge” per 1 ◦K can potentially be very high. With this in mind, we did not implement a selection of articles, nor provide authors with a podium, for a variety of research topics. The only requirement was that all processes needed to be performed using temperatures below the ambient level. In this issue, two of the articles are devoted to the field of cryosurgery, two cover frozen meat production and food preservation, and another three review processes used in distillation columns and heat exchangers. Another article describes methodology and calculation results of convective heat transfer near a hypersonic aircraft surface at ongoing airstream temperature near 60◦K. All of the articles involve numerical modeling, computation, and experimental research of heat and mass transfer at low temperatures. A fair amount of previous research worldwide shows that the typical standard models and algorithms with excellent approaches at high temperatures cannot be applied for processes used at a low-temperature range. A clear understanding of heatand mass-transfer features at low temperatures can help to improve theory and implement new processes of energy-saving and -generation technologies; expand our knowledge of food storage, thermal clothing design, and body and skin thermal treatment during cryogenic application or cryotherapy; and broaden our understanding of hypersonic motion in the stratosphere. This special issue is the first JEHT effort to bring special attention to the research and engineering community on heatand mass-transfer mechanisms occurring at below ambient temperature, its features, and methods for enhancement. As guest editor of this issue, I am grateful to all of the contributing authors for their challenging research efforts that they have decided to share with the worldwide thermal and fluids engineering community.

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前言

本期特刊包括针对自然科学和化学工程中一系列应用的低温传热和传质过程的不同方面的文章。令人惊讶的是，在 20 世纪和 21 世纪初，九个诺贝尔奖被授予物理现象的发现和研究，为此，这些工作是在低于环境水平的温度下进行的。这说明在这样的温度下，每 1°K 的“知识密度”可能非常高。考虑到这一点，我们没有针对各种研究主题实施精选文章，也没有为作者提供讲台。唯一的要求是所有过程都需要在低于环境水平的温度下进行。在这个问题上，其中两篇文章专门针对冷冻外科领域，两篇涉及冷冻肉生产和食品保鲜，另外三篇评论用于蒸馏塔和热交换器的过程。另一篇文章描述了在接近 60°K 的持续气流温度下高超音速飞机表面附近对流传热的方法和计算结果。所有文章都涉及低温传热传质的数值建模、计算和实验研究。世界范围内大量先前的研究表明，在高温下具有出色方法的典型标准模型和算法无法应用于低温范围内使用的过程。清楚了解低温下的传热传质特性有助于改进理论并实施节能发电技术的新工艺；扩展我们在低温应用或冷冻疗法期间的食品储存、保暖服装设计以及身体和皮肤热处理方面的知识；并拓宽我们对平流层高超音速运动的理解。本期特刊是 JEHT 首次致力于引起研究和工程界对在低于环境温度下发生的传热和传质机制、其特征和增强方法的特别关注。作为本期的客座编辑，我感谢所有贡献者所做的具有挑战性的研究工作，他们决定与全球热和流体工程社区分享。