Study on Heat Transfer Mechanism of Subcooled Pool Boiling under High Pressure

There is not a widely recognized theory which can explain the heat transfer of subcooled pool boiling under high pressure,so the mechanism of heat transfer of subcooled pool boiling is not clear.In order to disclosure the physical mechanisms of heat transfer for the subcooled nucleate pool boiling and obtain the relation between the bubble departure frequency and active cavity radius,the functions of heat transfer were analyzed according to the distribution of active cavity on boiling surfaces.A mathematical model was derived based on statistical treatment for the subcooled nucleate pool boiling heat transfer under high pressure.The proposed model for the heat flux of the subcooled nucleate pool boiling heat transfer is found to be a function of wall superheat,liquid subcooling,active cavity size,the contact angle and physical properties of fluid.No additional or new empirical constant is introduced.Comparing the model predictions with the existing experimental data,an excellent agreement between the model predictions and experimental data is found for different liquid subcoolings.The validity of the mathematical model for the subcooled nucleate pool boiling is thus verified.The analytical model reveals the physical principles of the heat transfer of subcooled pool boiling.