2127 トラバース型光学式ボイド計による水平伝熱管束 2 次側ボイド率計測  [in Japanese] Void fraction measurement in horizontal heat exchanger secondary side using traversing optical void probes  [in Japanese]

Void fraction distribution across a horizontal heat exchanger was measured using two optical void probes, which are traversed from the center elevation to the upper end of the bundle. Although the probe output signal is much different from the ordinary one because of different kind of the employed optical fiber, distribution is successfully obtained using the proposed methodology. The obtained distributions in the experiment performed under the postulated accident conditions show that the steam blanket phenomena will not occur because of sufficient two-phase flow convection. The distribution also shows that the flow regime transition from bubbly flow to churn-like flow, which has superior heat transfer, is induced at the void fraction of ∿0.5.