Experimental Investigation of Two-Phase
Countercurrent Flow Limit in Hydrogen Thermosiphon Loop of Cold Neutron Source
Du Shejiao,Bi Qincheng,Chen Tingkuan,Feng Quanke
(State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University,
Xi'an 710049, China)
Abstract: The flow pattern and flooding phenomena in vertical vapor-liquid
countercurrent flow were experimentally investigated using a two-phase thermosiphon loop
and R113 as working fluid for developing China Advanced Research Reactor (CARR) Cold
Neutron Source (CNS). Four flow patterns, i.e. falling film flow, falling film flow with
droplet entrainment at vapor entrance, churn flow near the vapor entrance, and the churn
flow through the whole tube, were observed. New data of the onset of flooding in a closed
system were obtained for three vertical tubes with inner diameters of 32, 34,and 45 mm
under pressures of 70- 820 kPa. A new correlation was developed and compared with existing
correlations.The result shows that this new correlation agrees very well with the data and
the McQuillan correlation.The new correlation presented can predict the onset of flooding
in the vertical tube with a sharp end in a closed system.
Keywords: flooding; two-phase countercurrent flow; thermosiphon loop; cold neutron source