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

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to reach a certain design power, calculation of flux on the receiver is meaning-
less and should not be done. The initial performance calculation fixes the values
of the constant design parameters listed in Table IV-2. Although it is possible
to change some of the receiver variables in later steps such as optimization, it
should not be done. The variables specified in that table should only be speci-
fied during an initial performance run.
After the initial performance calculation, it is possible to save the results on
a computer file. Thus, the initial performance can be calculated as a separate
computer run from optimization if this file is requested and saved as discussed
in Section V1.A-4. Similarly, it is possible to save the results of an optimization
calculation on a computer file for future use. Thus, it is possible to do the three
calculational steps as three distinct and sequential computer jobs, or it is possible
to combine the steps into a continuous computer job by specifying the right flags.
This discussion, however, will treat the three calculations as three distinct steps.
The second calculational step in'dptimizing a system design is to do the ac-
tual optimization. A two step optimization of tower and receiver dimensions is
generally more efficient. A search over a coarse grid of optimization variables lo-
cates an approximate optimuw design rapidly. A search over a fine grid of opti-
mization variables centered on the coarse grid optimum then finds a more exact
optimum. Both of these runs would use the same initial performance run its de-
scribed above; specifically, the annual average performance of each zone is used
during field buildup, so that no time calculation is done during the optimization.
Because calculations are based on a specific system performance, the user should
consider doing a modified initial performance calculation if the optimized system
design varies significantly from the parameters chosen during the original initial
performance calculation. However, in most instances the scaling of performance is
adequate and no iteration is required.
During the optimization process, the variables described in Table IV-2 will
and should remain fixed. A REC Namelist is the first namelist read as part of the
optimization process, and any variables which are not defined in REC at this time
default to the values defined in that namelist during the initial performance cal-
culation. This is important, because any receiver or tower variables which are
not being optimized will be set to the values specified as a result of this input
namelist.
The requested solar multiple can be specified in both the OPT Namelist and
the NLEFF namelist, but only the last specified value will be used. If a solar
multiple other than the default (SMULT=l.5) is desired, it must be specified
during the optimization calculation in one of these Namelists. The solar multi-
ple value is not used during an initial performance calculation, and is only used in
a final performance calculation for calculation of detailed annual energy, after the
system has already been designed and optimized. Thus, it is recommended that
a solar multiple value be specified only during the optimization procedure, since
that value will also be used in the final performance energy evaluation.
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