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

The final step of cavity receiver optimization is to fine tune the shape of
the heat exchanger surface within the cavity. The heat absorbing surface
of a cavity is modeled as a segment of a right circular cylinder centered
horizontally on the cavity aperture, as described in Sections 1I.E and V.A-
5(b). It is possible, based on the choice of the value H (Namelist REC),
that after optimization the top portion of the heat absorbing surface may
either have too low a flux or too high a flux. In the former case, the re-
ceiver may be oversized, and the user should rerun the second half of the
optimization (IOPTUM=l) using a different value of H in Namelist REC
to limit the heat absorbing surface height. In the latter case, the inter-
nal flux spillage onto uncooled surfaces such as the roof may cause design
failures, and so the user should rerun the second half of the optimization
using a larger heat absorber height. After the design has been finalized,
the user should run a final performance calculation of the optimum sys-
tern to generate detailed flux maps on the heat absorbing surface or other
surfaces of concern. If necessary, the user can then manually trim the heat
absorber to eliminate aFeaS whose incident energy is low enough to not re-
quire active cooling. However, if manual trimming is done, the user will
also have to recalculate by hand the cost of the receiver and any energy
costs, since no capital cost calculations are done during a final perfor-
mance calculation.
If the user allows the heat absorber height to be as large as possible dur-
ing optimization, as defined by equations V.A-8 and V.A-9, it is possible
that this calculated height will be very sensitive to the minimum radius
(RADMIN, Namelist FIELD). While it may be desirable to use the high
performance heliostats nearest to the tower, it may not be cost effective
because of the increased receiver costs. The user may wish to repeat the
cavity optimization procedure with a different value for RADMIN to in-
vestigate the sensitivity to this effect. However, it is likely that limiting
the heat, absorber height by specifying H (Namelist REC) will result in
similar receiver cost reductions without requiring the elimination of he-
liostats, so that varying RADMIN should be done after trying all other
optimization possibilities.
IV.C-4. Tower Position (Land Constrained Only)-In a system with a land
constraint (NLAND>O, Namelist FIELD), DELSOL will search for the optimal
position for the tower in the field. The tower does not have to be within the land
constraint; only the heliostats must be within the constraint. The code considers
NUMPOS (520) equally spaced discrete positions of the tower from (XTPST,
YTPST) to (XTPEND, YTPEND). The units for these variables are meters east
(for XTPST and XTPEND) or meters north (YTPST, YTPEND) of the center of
the first land constraint rectangle. (Also see Sections 1I.B-4 and 1V.D-2.)
I V. C-5. Storage Capacity-DELSOL sizes storage during system optimiza-
tion based on the longest operating day. (See Section V.A-8 for how storage sizes
are calculated.) The code assumes that by thus sizing storage no energy will be
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