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

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The most appropriate aiming strategy on the receiver should be used during
optimization. For designing flux limited receivers during system optimization, a
field of flux points can be specified in Namelist NLFLUX. However, during opti-
mization, flux will only be calculated and examined at four specified points out of
the field of flux points. It is suggested that the allowable fluxes for each of these
four points be specified individually, since the allowable flux will be different at
different receiver locations due to different receiver temperatures and flow rates.
It is further suggested that the four points checked during optimization also be
checked during the final performance run to determine the effect of the optimiza-
tion assumptions on the flux calculation during optimization.
During optimization DELSOL also sizes the heliostat field to meet the re-
quested design point power. This means that zones of heliostats are added by
the code to get the required power at the best energy cost. If heliostat density
optimization is not requested, the code will add zones or portions of zones of he-
liostats at the default heliostat densities until the power is reached. The result
of this process is a heliostat field which is no longer a uniform circular or north
biased field (IUSERF = 0 or l), but is instead a heliostat field specified zone by
zone (IUSERF = 2). Thus the value of IUSERF will be changed during system
optimization.
As a further step in field design, heliostat densities can be optimized as de-
scribed in Section 1V.B-l. DELSOL can simultaneously optimize the heliostat
densities and receiver dimensions. However, DELSOL cannot vary the tower
height while optimizing the densities. Therefore, the user must first do the above
system optimizations to find an optimum tower height for use during heliostat
density optimization. Unless the optimum tower height is the same as was chosen
during the initial performance calculation, a new performance calculation is also
required before optimizing the heliostat densities. Note that if optimizing helio-
stat densities results in a higher levelized energy cost at that design point power
level, then that optimization did not help, despite the fact that for a constant an-
nual energy the heliostat density optimization would have given a lower energy
cost.
Once an optimized system has been chosen, DELSOL will assign component
costs to each part of the system, based on its internal cost algorithms. This is
done at the end of system optimization, and is the only place in DELSOL where
component costs are determined, other than for the exception below.
If it is desired to optimize storage size for a fixed field size, that option should
be requested during the system optimization procedure. However, the actual cal-
culation is not done until a final performance run is done. Thus, output from sys-
tem optimization will always refer to the default calculated storage size, and costs
will be set accordingly. During a final performance calculation, the code will then
trade off the cost of storage against the cost of discarding energy and determine
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