A study on Flashing Phenomenon of Cryogenic Liquid

低温液体闪蒸现象的研究

• 批准号: 08455098
• 负责人: HANAOKA Yutaka
• 金额: $ 3.84万
• 依托单位: MURORAN INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455098/
• 关键词: Flashing; Rapid Depressurization; Mist Formation; Pressure-Undershoot; Pressure Recovery; Boiling

In the former study related to this research projects, it was pointed out that when liquid was subjected to a rapid reduction of pressure such as a breakdown of cryogenic storage tanks or pipes, a denser mist layr was formed over the liquid surface of vessel in case of extremely high depressurization rates, and that gave a strong influence to a boiling behavior to occur after that. So, in this study, flashing experiments on the relationship between the mist formation and boiling phenomenon was conducted by using the high speed video-camera being purchased during an initial year. And also an attempt have been made to clear the condition of inception of bubble formation under the rapid depressurization processes. In addition, these results are applied to the estimation of their quantities of pressure undershoot and pressure recovery due to the vapor generation along with the liquid boiling in comparison with the numerical simulation model.Results obtained through this research project ar … More e summarized as follows1.Experiments were carried out by using two kinds of vessel having the state of different wall roughness. As its result, it was observed that there are remarkable differences in both of pressure transients and mist growth rates even though the same condition. This can be considered due to the effects of the amount of preexsting nuclear sites on the wall surface.2.As a formation of thermal stratification in cryogenic liquid and making a high temperature of wall surface has not been avoidable because of the imperfect adiabatic wall caused by heat penetration (heat conduction, convection and radiation etc.) from the surroundings, a dependency of the wall charatevistics on the incipient condition of bubble formation appears strongly in comparison with those of normal or high temperature liquid in stored state.3.The transient pressure changes of the pressure-undershoot and the recovery pressure followed after that within the container may be determined by the mass balance between the vapor delivery rates through the orifice (corresponds to the breakdown and leakage area of vessel and pipes) and the explosive vapor generation rate after its depressurization process. Less

在与本研究项目相关的前一项研究中指出，当液体遭受快速的压力降低时，如低温储罐或管道的破裂，在减压速率极高的情况下，容器液体表面会形成较密的雾层，这对随后发生的沸腾行为有很大的影响。因此，在本研究中，使用第一年购买的高速摄像机对雾的形成与沸腾现象之间的关系进行了闪烁实验。并对快速降压过程中气泡形成的条件进行了初步探讨。并与数值模拟模型进行了比较，应用这些结果估计了由于蒸汽产生和液体沸腾引起的压力欠冲量和压力恢复量。通过这个研究项目得到的结果是……采用两种不同壁面粗糙度状态的容器进行了实验。结果表明，在相同的条件下，压力瞬态和雾的生长速率存在显著差异。这可以考虑到由于壁面上预先存在的核位的数量的影响。由于低温液体由于外界热渗透（热传导、对流、辐射等）造成的绝热壁不完善而无法避免热分层的形成和壁面的高温，因此与常温或高温储液相比，壁面特性对气泡形成的初始条件的依赖性很强。容器内欠冲压力和随后的恢复压力的瞬态压力变化，可以由通过孔口的蒸汽输送率（对应容器和管道的击穿和泄漏面积）与减压过程后爆炸蒸汽产生率之间的质量平衡来确定。少

项目成果

渡辺 敏晃 ほか3名: "液体窒素のフラッシングに関する実験的研究(壁面性状の違いによる現象への影響)" 第35回日本伝熱シンポジウム講演論文集. (1998)

Toshiaki Watanabe等3人：“液氮冲洗的实验研究（壁面特性差异对现象的影响）”第35届日本传热研讨会论文集（1998年）。

T.Watanabe, Y.Hanaoka and I.Tokura: "Flashing Phenomena of Liquid Nitrogen under Rapid Depressurizations" Proc.of 3rd KSME/JSME Thermal Engineering Conference. Vol.3. 421-426 (1996)

T.Watanabe、Y.Hanaoka 和 I.Tokura：“快速减压下液氮的闪蒸现象”第三届 KSME/JSME 热工会议论文集。

T.Watanabe et al.: "Flashing Phenomena of Liquid Nitrogen RapidDepressurizations" Procs.of 3rd KSME/JSME Thermal Engineering Confernce. Vol.3. 421-426 (1996)

T.Watanabe 等人：“液氮快速减压的闪烁现象”第三届 KSME/JSME 热工程会议论文集。

森越 義和 ほか3名: "急減圧による液体窒素の沸騰現象に関する実験的研究" 第34回日本伝熱シンポジウム講演論文集. 805-806 (1997)

Yoshikazu Morikoshi等3人：“液氮因快速减压而沸腾现象的实验研究”第34届日本传热研讨会论文集805-806（1997）。

T.Watanabe, Y.Hanaoka and I.Tokura: "Flashing Phenomenoa of Depressurized Liquid Nitrogen in a Pressure Vessel (2nd Rep., Mist formation and Behavior of Liquid Surface in early depressurization Process)" Trans.of JSME (B). 63-610. 2148-2153 (1997)

T.Watanabe、Y.Hanaoka 和 I.Tokura：“压力容器中减压液氮的闪蒸现象（第二次报告，早期减压过程中液体表面的雾形成和行为）”Trans.of JSME (B)。