Je. Pacheco et al., INVESTIGATION OF COLD FILLING RECEIVER PANELS AND PIPING IN MOLTEN-NITRATE-SALT CENTRAL-RECEIVER SOLAR POWER-PLANTS, Journal of solar energy engineering, 117(4), 1995, pp. 282-289
Cold filling refers to flowering a fluid through piping or tubes that
are at temperatures below the fluid's freezing point. Since the piping
and areas of the receiver in a molten-nitrate salt central-receiver s
olar power plant must be electrically heated to maintain their tempera
tures above the nitrate salt freezing point (430 degrees F, 221 degree
s C), considerable energy could be used to maintain such temperatures
during nightly shutdown and bad weather Experiments and analyses have
been conducted to investigate cold filling receiver panels and piping
as a way of reducing parasitic electrical power consumption and increa
sing the availability of the plant. The two major concerns with cold f
illing are (1) how far can the molten salt penetrate cold piping befor
e freezing closed, and (2) what thermal stresses develop during the as
sociated thermal shock. Cold fill experiments were conducted by flowin
g molten salt at 550 degrees F (288 degrees C) through cold panels, ma
nifolds, and piping to determine the feasibility of cold filling the r
eceiver and piping. The transient thermal responses were measured and
heat transfer coefficients were calculated from the data. Nondimension
al analysis is presented which quantifies the thermal stresses in a pi
pe or tube undergoing thermal shock. In addition, penetration distance
s were calculated to determine the distance salt could flow in cold pi
pes prior to freezing closed.