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Subcooled boiling regime map for water at low saturation temperature and subatmospheric pressure
Experimental Thermal and Fluid Science ( IF 2.8 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.expthermflusci.2020.110150
K. Wojtasik , R. Rullière , Z. Krolicki , B. Zajaczkowski , J. Bonjour

Abstract Subatmospheric pool boiling heat transfer was investigated experimentally. At low vapor pressure, the static head of the liquid column induces a non-negligible pressure gradient. This results in a local pressure-induced subcooling that makes the case of boiling at low vapor pressure with a high level of liquid a particular case of subcooled boiling. The experiments were conducted for variety of working parameters: three vapor pressures (2.4 kPa, 3.1 kPa, 4.1 kPa), four levels of liquid (15 cm, 28 cm, 35 cm, 60 cm) and five applied heat fluxes (3.6 W · cm−2, 4.4 W · cm−2, 5.2 W · cm−2, 6.1 W · cm−2 and 7.1 W · cm−2). Owing to a statistical analysis of the signal of a heat flux sensor coupled with high-speed video recording, four different boiling regimes were identified: the regime of convection or small popping bubbles, the regime of isolated bubbles, the regime of intermittent boiling and the regime of fully developed boiling. The small popping bubbles and the intermittent boiling regimes are specific to the low pressure boiling: they are governed by the phenomenon of condensation driven by the aforementioned static pressure induced subcooling. Finally, to provide a visual representation of the influence of the working parameters on the boiling behavior, a dimensionless boiling regime map was proposed. This type of representation is a tool to predict the boiling regimes from a set of operating conditions but it is also useful to interpret the physical phenomena involved and how they differ from those occurring at higher pressure.

中文翻译:

低饱和温度和亚大气压下水的过冷沸腾状态图

摘要 对负压池沸腾传热进行了实验研究。在低蒸气压下,液柱的静压头会产生不可忽略的压力梯度。这导致局部压力引起的过冷,这使得在低蒸气压下沸腾且液体含量高的情况成为过冷沸腾的特殊情况。实验针对各种工作参数进行:三个蒸气压(2.4 kPa、3.1 kPa、4.1 kPa)、四个液位(15 cm、28 cm、35 cm、60 cm)和五个施加的热通量(3.6 W· cm-2、4.4 W·cm-2、5.2 W·cm-2、6.1 W·cm-2 和 7.1 W·cm-2)。由于对热通量传感器的信号进行统计分析并结合高速视频记录,确定了四种不同的沸腾状态:对流状态或小气泡、孤立气泡状态、间歇沸腾状态和完全发展沸腾状态。小气泡和间歇沸腾状态是低压沸腾所特有的:它们由上述静压引起的过冷引起的冷凝现象控制。最后,为了直观地表示工作参数对沸腾行为的影响,提出了无量纲沸腾状态图。这种类型的表示是一种从一组操作条件预测沸腾状态的工具,但它也有助于解释所涉及的物理现象以及它们与高压下发生的物理现象有何不同。小气泡和间歇沸腾状态是低压沸腾所特有的:它们由上述静压引起的过冷引起的冷凝现象控制。最后,为了直观地表示工作参数对沸腾行为的影响,提出了无量纲沸腾状态图。这种类型的表示是一种从一组操作条件预测沸腾状态的工具,但它也有助于解释所涉及的物理现象以及它们与高压下发生的物理现象有何不同。小气泡和间歇沸腾状态是低压沸腾所特有的:它们由上述静压引起的过冷引起的冷凝现象控制。最后,为了直观地表示工作参数对沸腾行为的影响,提出了无量纲沸腾状态图。这种类型的表示是一种从一组操作条件预测沸腾状态的工具,但它也有助于解释所涉及的物理现象以及它们与高压下发生的物理现象有何不同。为了直观地表示工作参数对沸腾行为的影响,提出了无量纲沸腾状态图。这种类型的表示是一种从一组操作条件预测沸腾状态的工具,但它也有助于解释所涉及的物理现象以及它们与高压下发生的物理现象有何不同。为了直观地表示工作参数对沸腾行为的影响,提出了无量纲沸腾状态图。这种类型的表示是一种从一组操作条件预测沸腾状态的工具,但它也有助于解释所涉及的物理现象以及它们与高压下发生的物理现象有何不同。
更新日期:2020-10-01
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