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

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production. When each design power of interest (as specified by POPTMN,
POPTMX, and NUMOPT in Namelist OPT) is reached, the remaining plant cap-
ital costs and corresponding levelized energy cost (LEC) are calculated.
lV.B-2. Hefiostat Density Optimization (IHOPT=I)-DELSOL has an op-
tion to optimize the heliostat separations within each zone at the same time that
the field is being built up. In many problems the default densities are adequate.
However, if the field costs or heliostat shape are very different from the DELSOL
default values, then heliostat spacing optimization may be important. In all cases
it is prudent to optimize heliostat separations periodically to see if this produces
significant improvement in the energy cost, although Section 1V.B-3 will explain
why energy cost may not always be improved for a constant design point power.
The mathematical details of heliostat optimization are derived by Lipps (Ref-
”?
erence 4). DELSOL bases its heliostat optimization on these equations and as-
sumptions. A completely general optimization of the coordinates of every he-
liostat is not practical. Following the approach in Reference 4, the following as-
sumptions are made in order to simplify the problem:
the heliostat layout pattern within any one zone is determined by two
parameters: the “average” radial separation AR and the “average” az-
imuthal separation AAz;
the shadowing and blocking in a zone are determined only by the layout
parameters for that zone;
the optimum layout parameters to produce a given amount of annual en-
ergy will be determined. These may or may not be the optimum layout
parameters to produce a given design power. This subtle point is dis-
cussed in more detail below; and
the maximum deviation of the optimized AR and AAz is constrained to
be within a specified window around the initial AH. and AAz defined for
each zone in Namelist BASIC (IDENS). The size of the window of varia-
tion is controlled by DHOPT in Namelist BASIC.
Because the energy cost is not very sensitive to the heliostat spacings, the effect
of the simplifying assumptions in most practical problem is minimal.
In order to optimize heliostat separations, DELSOL must generate consider-
able information about the shading and blocking as a function of heliostat posi-
tion. When heliostat density optimization is requested, the code does 25 shad-
owing and blocking calculations for each zone during the initial performance cal-
culation. The calculations are done on a 5x5 grid of heliostat separations. One
side of the grid has constant density lines; the other side has constant aspect ratio
lines (= 0.5AR2 - 0.5AAz2).The grid is used to interpolate the performances and
performance derivatives with respect to separation required in heliostat spacing
optimization. The grid is centered on the density and aspect ratio determined for
each zone by the AR and AAz defined in Namelist FIELD. The size of the grid is
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