A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...

*
least accurate assumption of optimization, since if storage is large, then the tur-
bine will operate mostly at design point power conditions. Finally, parasitic losses
are dependent on HROP, the amount of storage, and other annual values such as
annual weather or maintenance outages. Also, this final annual energy value will
be reduced by the maintenance outage factor (PF).
For a final performance run (IPROB=O), energy is accounted for at NYEAR
days and HRDEL time increments through the day. That is, power on the re-
ceiver at each point in time is reduced by receiver losses at that time, is routed
to storage and discarded if storage is full, and is then routed to the turbine. If
the power level is high enough to run the turbine at full power, then the conver-
sion efficiency will be ETAREF, or else the conversion efficiency will be FEFF
x ETAREF. Operating parasitic losses will reduce the output from the turbine.
This gross energy value will be reduced by the maintenance outage factor. The
actual times of all operations are recorded and summed, and the total summa-
tions are used to calculate the level of non-operating parasitic energy losses.
Although the detailed performance energy summation is more detailed than
that used during system optimization, at least three factors keep that calcula-
tion from matching well any known output from a solar power plant. First, the
weather/insolation in actuality varies with time and may not equal the DELSOL
assumed values during any specific time interval. This may affect how much en-
ergy is discarded because storage is full or how much energy is left in storage
when the receiver shuts down, as well as just the energy produced during that
time interval. Second, some additional amount of lost energy is going to be re-
quired over what DELSOL predicts in order to start up the turbine and heat ex-
changer equipment. It may take as much as an hour of feeding thermal energy
to the turbine before any electricity is produced by the turbine. Finally, different
operational tactics may produce different amounts of annual energy for the same
system and set of conditions. DELSOL assumes that the turbine starts when the
receiver starts and that storage is depleted every night. From an income stand-
point, however, it may be wise to operate the turbine only during high energy de-
mand times when the price paid for the energy will be highest, even if that means
either throwing away energy at other times or having a larger storage tank than
DELSOL designs in order to operate at certain times.
DELSOL annual energy results should be considered by the user to be ap-
proximate values. If more exact numbers are desired, a separate computer code
should be used which incorporates actual weather and operating strategies in or-
der to calculate annual energy. The field performance and cost information from
DELSOL will be reasonably accurate, however, so that a final levelized energy
cost could be calculated using DELSOL’s cost/economic information and the an-
nual energy from an independent calculation, where that independent calculation
could use the field performance information from a DELSOL final performance
calculation.