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of the transient non-boiling heat transfer have been made possible. The
results obtained in this chapter are also useful in a natural circulation
problem in the entire nuclear system which is dealt with in Chapter W.
The.second category of the transient boiling and two-phase flow
phenomena corresponds to a larger Q/dhe value. In this case, the boiling
heat transfer and burnout occur in high steam quality two-phase flow.
The flow regime is usually annular or annular dispersed flow. The burn-
out heat flux under this condition is relatively low. Furthermore, the
boiling heat transfer coefficient and burnout heat flux (in this case,
often called dryout heat flux) are considerably affected by the steam
quality at the outlet which reflects the integrated effects of the entire
heated length. Therefore, they depend on the length of the heated section.
These phenomena are often observed in a slow transient boiling. ,Under such
a circumstance, the boiling heat transfer and dryoutheatflux are deter-
mined by the liquid film flow rate at the heated surface,-the droplet
flow rate in the core flow and droplet size and its distribution. There-
fore, in Chapters III through V, the problems on the hydrodynamics of the
annular and annular diapersed flow have been analysed. In Chapter III,
the mean droplet size and its distribution are analysed and the correlations
for these parameters have been developed. In Chapter IV , the droplet
entrainment rate from the liquid film at the wall and the deposition rate
of the droplets to the wall have been analysed. These entrainment and
deposition rates determine the film flow rate and the droplet flow rate
under both transient and steady state conditions.
While Chapters III and JV are involved in the annular dispersed flow
with a positive liquid flow rate, Chapter V deals with the dispersed flow
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