Availability analyses for heterogeneous nucleation under steady heating in pool boiling

Onset of heterogeneous nucleation is analyzed in this paper based on the criterion that change in the derivative of the availability function with respect to bubble radius is equal to zero. Comparisons of the predicted nucleation parameters obtained based on this criterion with those obtained previously based on the criterion that the change in Gibbs function equal to zero are made. It is found that the Gibbs function nucleation criterion is the necessary condition for onset of bubble nucleation while the availability nucleation criterion is the sufficient condition for onset of nucleation. Comparing with the Gibbs function criterion, the availability criterion predicts a larger nucleation radius at the same wall temperature and requires a higher nucleation temperature at the same heat flux although the differences in values are small.