Void fraction measurement in subcooled-boiling flow using high-frame-rate neutron radiography

A high-frame-rate neutron radiography (NR) technique was applied to measure the void fraction distribution in forced-convective subcooled-boiling flow . The focus was experimental technique and error estimation of the high-fra me-rate NR. The results of void fraction measurement in the boiling flow we re described. Measurement errors on instantaneous and time-averaged void fr actions were evaluated experimentally and analytically. Measurement errors were within 18 and 2% for instantaneous void fraction (measurement time is 0.89 ms), and time-averaged void fraction, respectively. The void fraction distribution of subcooled boiling was measured using atmospheric-pressure w ater in rectangular channels with channel width 30 mm, heated length 100 mm , channel gap 3 and 5 mm, inlet water subcooling from 10 to 30 K, and mass velocity ranging from 240 to 2000 kg/(m(2).s). One side of the channel was heated homogeneously. Instantaneous void fraction and time-averaged void fr action distribution were measured parametrically. The effects of flow param eters on void fraction were investigated.