DEVELOPMENT OF AN ONSET OF NUCLEATE BOILING MODEL AND A NUCLEATE BOILING HEAT TRANSFER MODEL WITHIN THE FOULING LAYER

The fouling on the reactor fuel cladding surface affects the boiling heat transfer, and the boiling within the fouling involves both nucleate boiling and film boiling regimes. It is crucial to establish the boiling onset model to determine the boiling regime within the fouling layer. By simplifying the fouling layer as the porous media with steam chimneys, it is assumed that the cladding temperature is exactly the saturation temperature at the onset of nucleate boiling, and the energy still relies on convective heat transfer when nucleate boiling occurs. A new model is proposed to determine the onset of the nucleate boiling within the fouling. And the wall temperature at nucleate boiling is obtained by simple linear interpolation. The errors of the onset of the nucleate boiling and nucleate boiling model from the experimental results is within 15% and 20%, respectively.