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

the receiver may occur at a location other than those points being tested during
optimization. In this case, a flux map generated during a final performance run
using up to 169 points will indicate where the actual peak flux occurred.
Flux limits should be chosen based on one of two criteria: 1) to design to a
given lifetime for a receiver, due to cyclic loads, and 2) to ensure that tempera-
ture limits are not exceeded. In the former case, the flux limit which is chosen
should not be one which the user should never expect to exceed. In an actual re-
ceiver system, insolation levels will vary due to weather conditions and time of
year/day, so that some cyclic loads will have lower flux levels and will have less
effect on lifetime, while other cyclic loads will have higher flux levels than at de-
sign point and will have a greater effect on lifetime. It is the total effect of these
different flux levels on lifetime that is important, and so the flux limit to be de-
signed to at the design point should be some kind of an average limit. In the case
of keeping temperature levels below certain limits, the user should again realize
that actual insolation levels will vary and may at some point in time exceed the
design point value REFSOL. Thus, either the system should be designed with a
larger REFSOL, a lower flux limit, or during system operation the user should
plan on reducing the number of heliostats focused on the receiver when actual in-
solation exceeds the design point value of REFSOL.
Flux point locations during optimization are initially defined relative to the
receiver type and dimensions as described in the REC Namelist immediately pre-
ceeding the OPT Namelist. The following steps should be used in setting up a
flux limited design run:
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(1) Define the type and initial dimensions of the receiver desired on the REC
Namelist preceeding the OPT Namelist. This receiver should be consis-
tent with the field and type of receiver used in the initial performance run
whose results will be used during this optimization.
(3)
Set up a grid of flux points on the heat absorbing surface of this receiver,
using the Namelist NLFLUX following the OPT Namelist. The user is
cautioned to be certain that the user-specified flux surface does coincide
with the DELSOL-defined heat absorbing surface, since during optimiza-
tion the flux surface will be adjusted based on the changes being made to
the heat absorbing surface. However, the flux surface does not have to be
the same physical size as the heat absorbing surface. It can be larger, thus
looking at the effects of spillage, or smaller, which might enable the user
to examine a critical area in detail. It is suggested that the grid of flux
points which is set up here be used during a final performance calculation
also, so that the values of the points which are actually checked during
optimization can be compared to the more accurately calculated values in
the performance run to see the effects of the approximations used during
system optimization.
Choose NFLXMX (54) points from the grid of flux points defined in step
(2) at which the flux limits are to be tested. Specify the number of each