Interconnection between dynamics of liquid boiling-up and heat transfer crisis for nonstationary heat release

This paper deals with investigation results on crisis phenomena for nonstationary heat release under the conditions of free convection and in falling liquid films. It is shown that the character of the crisis development and the critical heat flux for nonstationary heat release significantly depend on the characteristics determining the temperature head of liquid boiling-up. According to experimental data with an arbitrary temporal function of heating, the character of the dependence between the critical heat flux and the heat release increasing rate is significantly effected by ready nucleation sites. It is found that a change in the nonstationary critical heat flux in the range of high times between impulses for periodic heat release is connected with deactivation of ready nucleation sites on the heat-releasing surface.