Numerical solution of non-stationary conjugated problem of heat transfer in a tube in the regime of boiling beginning

The results of solving a non-stationary conjugated problem of heat transfer at subcooled boiling under the conditions of forced flow in a tube are presented. A system comprising three equations: equation of heat transfer for the wall, energy equation for the flow and equation of vapour bubble diffusion under boiling is numerically solved. The solution permits: a) to obtain correlation between basic thermal processes and measured characteristics of vapour-liquid flows; b) to predict significant, applicable local and integral parameters of flow such as: distribution by length of mean cross section of true void fraction; distribution by length of maximum true void fraction; generation of temperature fields in the wall and flow at different moments of time; obtaining Nu numbers at different materials of the wall in the range of parameters, where direct experimental data are not obtained, for example, at different perturbations: excursion and drop of power supplied to the channel, perturbation by flow rate, by heat transfer, etc