EXPERIMENTAL STUDY OF THE NON-STATIONARY HEAT FLUX EFFECT ON THE ONSET OF NUCLEATE BOILING AND MAXIMUM BUBBLE DIAMETERS IN THE SUBCOOLED BOILING FLOW
The initial stages of formation of the developed nucleate boiling were investigated over the increasing heat flux range of 0.52−1.71 MW/m². The non-stationary temperature field of heated liquid layers was described by numerical modelling. The effects of heat release conditions and inlet water temperature on the bubble maximum diameter and nucleation frequency were studied. The present experiment data on the maximum bubble diameter was compared with the theoretical predictions. Calculations on the basis of prediction model showed that it is impossible to employ analytical relations to describe non-stationary nucleate boiling. The approach based on the heat balance proved to be the most promising for approximating both stationary and non-stationary data without major changes. To build a general explosive boiling model, the parameters of the nucleate boiling should be calculated on the basis of the detailed temperature fields in the liquid and take into consideration the interface heat transfer.