A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
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the receiver may occur at a location other than those points being tested during<br />
optimization. In this case, a flux map generated during a final per<strong>for</strong>mance run<br />
using up to 169 points will indicate where the actual peak flux occurred.<br />
Flux limits should be chosen based on one of two criteria: 1) to design to a<br />
given lifetime <strong>for</strong> a receiver, due to cyclic loads, and 2) to ensure that tempera-<br />
ture limits are not exceeded. In the <strong>for</strong>mer case, the flux limit which is chosen<br />
should not be one which the user should never expect to exceed. In an actual re-<br />
ceiver system, insolation levels will vary due to weather conditions and time of<br />
year/day, so that some cyclic loads will have lower flux levels and will have less<br />
effect on lifetime, while other cyclic loads will have higher flux levels than at de-<br />
sign point and will have a greater effect on lifetime. It is the total effect of these<br />
different flux levels on lifetime that is important, and so the flux limit to be de-<br />
signed to at the design point should be some kind of an average limit. In the case<br />
of keeping temperature levels below certain limits, the user should again realize<br />
that actual insolation levels will vary and may at some point in time exceed the<br />
design point value REFSOL. Thus, either the system should be designed with a<br />
larger REFSOL, a lower flux limit, or during system operation the user should<br />
plan on reducing the number of heliostats focused on the receiver when actual in-<br />
solation exceeds the design point value of REFSOL.<br />
Flux point locations during optimization are initially defined relative to the<br />
receiver type and dimensions as described in the REC Namelist immediately pre-<br />
ceeding the OPT Namelist. The following steps should be used in setting up a<br />
flux limited design run:<br />
112<br />
(1) Define the type and initial dimensions of the receiver desired on the REC<br />
Namelist preceeding the OPT Namelist. This receiver should be consis-<br />
tent with the field and type of receiver used in the initial per<strong>for</strong>mance run<br />
whose results will be used during this optimization.<br />
(3)<br />
Set up a grid of flux points on the heat absorbing surface of this receiver,<br />
using the Namelist NLFLUX following the OPT Namelist. The user is<br />
cautioned to be certain that the user-specified flux surface does coincide<br />
with the DELSOL-defined heat absorbing surface, since during optimiza-<br />
tion the flux surface will be adjusted based on the changes being made to<br />
the heat absorbing surface. However, the flux surface does not have to be<br />
the same physical size as the heat absorbing surface. It can be larger, thus<br />
looking at the effects of spillage, or smaller, which might enable the user<br />
to examine a critical area in detail. It is suggested that the grid of flux<br />
points which is set up here be used during a final per<strong>for</strong>mance calculation<br />
also, so that the values of the points which are actually checked during<br />
optimization can be compared to the more accurately calculated values in<br />
the per<strong>for</strong>mance run to see the effects of the approximations used during<br />
system optimization.<br />
Choose NFLXMX (54) points from the grid of flux points defined in step<br />
(2) at which the flux limits are to be tested. Specify the number of each