Convective post-CHF film boiling heat transfer

Studies on both dispersed flow and inverted annular flow film boilings are introduced. The research is concerned only with low pressure and low mass flowrate condition. The experimental ranges were: P = 2-7 bar, G = 25-130 kg/m.s, Xin = 5-85%, q = 20-95 kw/m2, for dispersed flow; p = 3-7 bar, G = 45-160 kg/m2.s, Δtsubλ = 1-20 deg C, q = 50-90 kg/m2, for inverted annular flow. Theoretical models and their comparison with data are discussed respectively for both dispersed flow and inverted annular flow. To date, reliable information of liquid droplets is still lacking. Improvement in liquid drops bebavior is important. Not only little information on vapour film behavior, but wall temperature data are also seldom availabe for inverted annular flow of water. All proposed correlations may not be valid for low quality film boiling for water. No satisfactory predictions are available. It is possible to have a reliable data bank to remove the uncertainty in the prediction of post-DNB heat transfer, only after further work remains to be done to incorporate the vapour film characteristics