Rewetting Analysis of Hot Vertical Surfaces With Precursory Cooling by the Heat Balance Integral Method

Abstract

The effect of precursory cooling on conduction-controlled rewetting of both slab and solid cylinder is analyzed by the heat balance integral method. A constant heat transfer coefficient is assumed in the wet region behind the wet front, while an exponentially decaying heat flux is assumed in the dry region ahead of the wet front. The physical problem is characterized by two dimensionless constants describing the extent of precursory cooling and three dimensionless numbers, namely, Peclet number, Biot number, and the nondimensional temperature. Results of the present solution are found to be in good agreement with other analytical solutions obtained through the Weiner–Hopf technique and the separation of variables as well as with the published experimental data for different coolants over a varied range of coolant flow rate. It is seen that precursory cooling increases the rewetting velocity particularly at higher flow rates. If it is neglected, the model grossly underpredicts the quench velocities.