Water Reservoir: An often overlooked problem
is the fact that the solar system has to be shut
down and started every day. In the absence of
the heating source, all the two phase flow
sections will be filled with liquid water. This
extra water, which is needed to fill the void left
by the condensing steam in those sections, is
provided by the steam drum. This can be a
significant amount of water accounting for
around 10% of steam drum total volume.
Typically, the steam drum is the only place
where the two phases exist after a shutdown.