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

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furthermore, that the assumed turbine efficiency is a worst case estimate (see
Sections 1II.G-5 and 1V.A-7). Thus, the capacity factor value calculated and dis-
played during a DELSOL optimization is only an estimate at best. By optimizing
the physical storage size, the user will be changing the actual capacity factor, as
well as storage and energy costs, because the amount of available stored energy
will change without changing solar multiple. DELSOL will not recalculate the ca-
pacity factor.
1V.C-6. Heliostat Field Boundaries-The user has no control over this part of
the system optimization. DELSOL will optimize the boundaries of the heliostat
field as described in Section 1V.B-1. The heliostat field is always constrained to
lie within the zoning defined by the variables RADMIN and RADMAX, and may
be further subjected to a land constraint as described in Section 1V.D-2.
IV. C- 7. Heliostat Spacings-DELSOL has an option for optimizing the spacing
of heliostats within each zone (IHOPT-1 in Namelist OPT). The optimization
has three constraints: (1) the layout pattern is always a radial stagger pattern;
(2) the optimized densities and aspect ratios cannot be more than 3~20% from the
initial densities and aspect ratios defined in Namelist FIELD (the range is set by
the variable DHOPT in Namelist BASIC): and (3) the tower height cannot be
optimized simultaneously with optimizing heliostat spacings (see Chapter VI).
1V.D. Constraints on System Optimization/Desipn
During system optimization, DELSOL can design systems which meet flux
limitations on the receiver or which have land availability constraints. In this
case, no system will be accepted as an optimum unless the appropriate con-
straints are satisfied.
I V. D-1. Receiver Flux Constraint During Optimization-DELSOL has an op-
tion to calculate and monitor the flux at the design point at up to four points
on the receiver surface (NFLXMXs4). The maximum allowable values at these
points are specified by FLXLIM(1) watts/m2, where I=l, NFLXMX. If the flux
limit at one of the points exceeds its limit, field buildup during optimization is
halted for that combination of receiver and tower dimensions.
The flux values which are calculated during optimization are only approxima-
tions of actual peak flux levels, for at least three reasons. First, the design point
insolation is assumed to be REFSOL (Namelist BASIC), which may not match ei-
ther a measured insolation at a design point time or a calculated insolation using
one of the insolation models available in DELSOL during a performance calcula-
tion. Second, in calculating the flux during optimization, DELSOL assumes that
the relative shape of the flux profile at the design point is the same as the relative
shape of the annual average flux profile as described by an initial performance
calculation. This assumption is more correct for surround fields than for north
biased fields, but in any case it depends on the choice of the design point by the
user. This assumption usually causes the optimization calculation of flux to over-
predict the actual flux level at a point on the receiver. Third, the peak flux on
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