Measurement of the liquid sublayer thickness during onset of DNB

Nguyen, T.-B.; Shibamoto, Yasuteru ; Satou, Akira ; Okawa, Tomio*

Accurate predicting DNB heat flux in subcooled flow boiling is vital for safety assessment of nuclear reactors or other high heat flux components. A mechanistic model for predicting DNB heat flux has become a demanding task, because existing correlations are no longer accurate with the development of new generations of reactors with more complex working environments than before. Measurement of the liquid layer thickness beneath the vapor blanket moving along the heated wall is among important factors for the development of DNB mechanistic model. Available data of the sublayer thickness or so-called macro layer has been measured but only for pool boiling. The present study aims to produce a dataset of liquid sublayer thickness for flow boiling using laser displacement sensor. Synchronized high-speed movies are also collected for analyzing the change of the data during the period when the mass vapor pass.