哈尔滨工程大学学报2018，Vol.39Issue(5)：870-875,6.DOI:10.11990/jheu.201701006
套管式换热元件内流动不稳定性研究
Flow instabilities in a thimble-based heat transfer element
摘要
Abstract
To understand natural circulation flow instabilities in a thimble-based heat transfer element, an experi-mental study was conducted on a monotube experimentation unit using different heating powers and inlet subcooling indices to analyze the unstable flow phenomena that may occur at low pressures,as well as on their driving mecha-nisms.The unstable region was confirmed and the geyser and the flashing instability boundary represented by di -mensionless inlet subcooling and heating power were obtained.Results indicate that the geysering and flashing in-stability flow occurred successively,following the decrease in inlet subcooling.Compared with conventional natural circulation loops,the circulation flow of the thimble-based heat exchange element is unique in the fact that the fluid in the rising segment transfers heat to the fluid in the downcomer;therefore,the fluid temperature decreases in the rising segment and the condensation of steam bubbles becomes more serious.This effect easily causes geysering in-stability and delays the occurrence of flashing instability to some degree.When the flashing phenomenon occurs, the scope of the ratio between the flow oscillation period and the necessary time of fluid passing in the rising seg -ment becomes 0.8~1.1.关键词
套管式换热元件/自然循环/流动不稳定性/间歇泉振荡/闪蒸不稳定/不稳定边界Key words
thimble-based heat transfer element/natural circulation/flow instabilities/geysering oscillations/flash-ing instability/unstable boundary分类
能源科技引用本文复制引用
陈凯伦,阎昌琪,孟兆明,丁涛..套管式换热元件内流动不稳定性研究[J].哈尔滨工程大学学报,2018,39(5):870-875,6.基金项目
国家自然科学基金项目(11475048). （11475048）
