Transient Heat Transfer in a Tube during Pressure Reduction from Supercritical to Subcritical Pressure

从超临界压力降至亚临界压力期间管内的瞬态传热

基本信息

批准号：
16560188
负责人：
MORI Hideo
金额：
$ 2.43万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16560188/
关键词：
Transient heat transfer Pressure reduction Supercritical pressure Critical heat flux condition In-tube flow SCPR

项目摘要

For the development of a supercritical pressure water cooled power reactor, experiments were carried out to clarify the characteristics of the transient heat transfer in a tube during rapid pressure reduction from supercritical to subcritical pressure, using HCFC22 as the test fluid, and transient heat transfer characteristics were clarified comparing with data under steady state conditions. The test section was a circular tube of 4.4 mm I.D. The pressure was in the range of a supercritical pressure 5.5 MPa (a reduced pressure of 1.1) down below to a subcritical pressure 4.0 MPa (a reduced pressure of 0.8), and the mass velocity was 400 and 700 kg/(m^2s).Following results were obtained.1.Under steady state conditions, a reduction in the heat transfer due to the occurrence of critical heat flux condition of film boiling was found in the region of pressure slightly below the critical pressure of 5.0 MPa, even when the heat flux was such a low value at which no heat transfer deterioration was observed at a supercritical pressure of 5.5 MPa. The heat transfer reduction was found at lower pressure with increasing heat flux.2.In the transient conditions of reducing pressure, the same reduction of heat transfer due to the occurrence of film boiling was also recognized in the pressure region slightly below the critical pressure, even when no heat transfer deterioration was observed at the initial supercritical pressure condition. The heat transfer reduction and resulting tube wall temperature rise, however, were noticed to continue down to the pressure region much lower than the critical pressure. During the pressure reduction, the maximum tube wall temperature in the film boiling was kept almost constant independently of pressure reduction rate. Furthermore, the maximum temperature became higher with an increase of heat flux.

针对超临界压力水冷动力堆的研制，以HCFC22为试验流体，进行了超临界至亚临界快速降压过程中管内瞬态传热特性实验，明确了管内瞬态传热特性。与稳态条件下的数据进行比较得到澄清。测试部分是内径 4.4 mm 的圆管。压力为超临界压力5.5MPa(减压1.1)以下至亚临界压力4.0MPa(减压0.8)的范围，质量速度为400、700kg/(m^2s)得到以下结果： 1.在稳态条件下，在压力稍低的区域发现由于膜沸腾临界热通量条件的出现而导致传热减少超临界压力为5.0MPa，即使热通量为在5.5MPa的超临界压力下未观察到传热劣化的低值。随着热通量的增加，在较低压力下发现传热减少。2.在减压瞬态条件下，在略低于临界压力的压力区域也发现由于膜沸腾的发生而导致传热减少，即使在初始超临界压力条件下没有观察到传热恶化。然而，人们注意到传热减少和由此产生的管壁温度升高继续下降到远低于临界压力的压力区域。在减压过程中，薄膜沸腾中的最高管壁温度几乎保持恒定，与减压速率无关。此外，随着热通量的增加，最高温度变得更高。