The process of subcooled water boiling is qualitatively described based on data obtained using gradient heat flux measurement. The proposed method was used for the first time for measuring the heat flux per unit area during film boiling that takes place on the endface of a cylinder submerged in subcooled water. Based on these results, the time distribution of the heat flux per unit area are constructed and the relationship between the heat flux per unit area and heat-transfer coefficient is estimated.

For the first time, heat transfer during condensation has been studied using gradient heat flux measurement. The applicability of the new method has been tested on a model of a well-studied object—a circular pipe. The experiments involved heat transfer investigation during condensation of saturated water vapor at the outer and inner surfaces of the pipe. Gradient heat flux measurement is shown to be highly informative, which opens up new prospects for research in the field of heat transfer during phase transformations, has been revealed.