In the present work, in the case of a tube-rupture close to the
tube sheet, and assuming an isentropic expansion of the process
fluid to the rupture area, Peng-Robinson (1976) equation of state
(EOS) as implemented in RefProp 9.1, Lemmon et al. (2010), was
used to determine the isentrope starting from the initial condition
of pressure and temperature at the respective chambers on the
tube-sheet process side. Two-phase flow is accounted for by the
EOS of the mixture expansion to the shell pressure. The mass flux
along a tube, however, follows the Fanno flow governing equations,
again form the initial condition of pressure and temperature at the
respective chambers on the tube-sheet process side, and along the
tube to the rupture location, again accounting for the two-phase
flow via the EOS in RefProp. The Fanno flow governing equations
used are described as follows: