A CFD analysis has been performed
for the simulation of a molten sodium
hydroxide heat exchanger. Two differ-
ent designs were investigated: Double
pipe and U-tube heat exchangers for
3 different pressures (1,2 and 5 [bar])
of the working fluid, which was wa-
ter. Then the FEM analysis of Ther-
mal stress was performed. The sim-
ulations ran with the assumption that
stress induced by constrained expan-
sion is covered by the heat exchanger
design apart from one for the atmo-
spheric pressure for the U-tube heat
exchanger. In this simulation, it was
assumed that the baffle is pressed on
the heat exchanger tubes and any ex-
pansion of the tubes is constrained by
the baffle. Additionally, the Factor of
Safety for each simulation was com-
puted in order to find out, if the stress
exceeds the tensile yield strength and
thus the elastic range. The compari-
son between each of the scenarios re-
vealed that considering the same prop-
erties and boundary conditions Dou-
ble pipe HX produces higher amounts
of thermal stress, but still keeps the
levels of Factor of Safety at an accept-
able level. Moreover, it has been found
that it is necessary to apply safety mea-
sures to the expansion of the pipes as
the Factor of Safety for a case with con-
strained expansion was less than 1 and
thus elastic range was exceeded and
the pipes are irreversibly damaged