Abstract

Recommendations are given on designing thermosiphons (TS) prepared on the basis of the experience that the authors gained in designing more than 4000 TSs for heat-recovery steam generators and the results of long-term investigations and tests carried out to study thermohydraulic and corrosion processes in vertical and inclined TSs filled with steam-water mixture. The results of similar studies performed by other authors are analyzed. References are given to the regulations on the design of heat transfer equipment for thermal and nuclear power stations. The requirements for TS construction materials, the degree of TS filling with water, and the TS vacuum level are outlined. Whether the evacuation of TS may be abandoned was assessed. Measures are proposed to prevent depressurization on water freezing in TSs. Recommendations are given on the calculation of thermohydraulic characteristics and steam-and-gas distribution in vertical or inclined TSs. The conditions of displacement by a steam flow of noncondensable gases, including air, to the top of the condensation zone in a thermosiphon are considered. Various regimes of axial heat transport and heat transfer are described for pure steam condensation (including film condensation, bubble condensation, distribution of different regimes of steam condensation, and condensate cooling along the height of the condensation zone during “flooding”). Heat transfer in the steam condensation from an air-steam mixture (the diffusion component of thermal resistance), maximum power, and the conditions for poorer cooling of the TS heating zone (“flooding,” steam separation at the upper generatrix of the heating zone in an inclined thermosiphon) are examined. Thermosiphons feature a countercurrent flow of steam and its condensate in a single flow with the same mass flowrates. Hence, a special case of “flooding” affecting the maximum power of the thermosiphon, the effect of the incoming steam flow on the heat transfer rate during film condensation, steam-and-gas distribution in a top-plugged channel, corrosion processes in thermosiphons, and hydrogen diffusion through the thermosiphon wall should also be studied.

中文翻译：

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热虹吸管热工水力特性的设计和预测的细节

摘要

在设计热虹吸管（TS）时，根据作者在为热回收蒸汽发生器设计4000多个TS时获得的经验以及为研究热工水力和腐蚀过程而进行的长期研究和测试的结果，提出了建议在充满蒸汽和水混合物的垂直和倾斜TS中。分析了其他作者进行的类似研究的结果。参考了有关热电站和核电站传热设备设计的规定。概述了TS建筑材料的要求，TS填充水的程度以及TS真空度。评估了是否可以放弃TS的疏散。建议采取措施防止TS中水冻结降压。给出了关于在垂直或倾斜TS中的热工水力特性和蒸汽和气体分布的计算建议。考虑了包括热空气在内的不可冷凝气体（包括空气）的蒸汽流向热虹吸管中冷凝区顶部的置换条件。描述了用于纯蒸汽凝结的各种轴向传热和传热方式（包括薄膜凝结，气泡凝结，蒸汽凝结的不同形式的分布以及在“注水”期间沿凝结区高度的凝结水冷却）。来自空气-蒸汽混合物的蒸汽冷凝中的热传递（热阻的扩散成分），最大功率以及TS加热区冷却效果较差的条件（“注水，检查了倾斜热虹吸管中加热区上母线的蒸汽分离情况。热虹吸管的特征是，蒸汽和其冷凝物以相同的质量流量在单股流中形成逆流。因此，“溢流”的特殊情况会影响热虹吸管的最大功率，薄膜凝结过程中流入的蒸汽流量对传热速率的影响，顶部堵塞通道中的蒸汽和气体分布，热虹吸管的腐蚀过程，氢也应通过热虹吸管壁扩散。