FLOW BOILING HEAT TRANSFER IN VERTICAL SLUG AND CHURN FLOW REGION
Heat transfer characteristics of the slug/churn flow region are very different from those of the annular flow region. This fact is not recognised while designing industrial reboilers due to lack of suitable predictive methods for this region. A slug flow model is developed here to address this problem. The predictions of this model are compared with the published experimental data for boiling water. In general the experimental trends, which are otherwise difficult to explain, are predicted correctly by the model. The agreement between the data and the predictions is good at low flow rates. The possible explanations for not so good agreement at high flow rates are discussed. The model, in its present form, is useful in providing the lower limit of slug/churn flow heat transfer coefficients. It can be developed further to make it more realistic and to handle more complex practical situations.