The Effect of the Location of Nucleation Sites on the Thermal-Hydraulic Stability of a Short-Tube Natural Circulation Loop

Abstract

The use of small two-phase natural circulation loops is an attractive option for efficient cooling applications and innovative steam generators. An experimental study was conducted to examine how the thermal-hydraulic stability and operating conditions of these devices are affected by nucleation sites. A very smooth glass tube with artificial nucleation sites was used as a boiling channel. The mass flow rate was obtained as a function of heat flux and nucleation site location. Nucleation sites have a strong impact on stability behavior, particularly for low heat flux levels. The observed flow instabilities were analyzed with regard to nonlinear effects and chaotic behavior.