Rewetting of hot horizontal tubes

Experiments on the rewetting and refilling of hot horizontal tubes are presented. The experiments were carried out under a wide range of initial and boundary conditions. The effect of tube wall thickness, initial wall temperature, inlet mass flux and inlet subcooling were investigated. The results were used to identify the flow-regimes associated with the rewetting and refilling of horizontal tubes. Although, stratified flow was commonly observed, inverted annular flow was observed under high mass flux conditions and skewed annular flow was observed under limited conditions. The results were interpreted in terms of a new surface rewetting criterion which suggests that surface rewetting is initiated when the vapour film thickness in film boiling is reduced to a critical value irrespective of the surface temperature. (orig.)