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

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configurations may give different flux profiles and peak fluxes, as well as different
internal spillages.
For cavity receivers, DELSOL tests each flux point to insure that it can be
seen through the aperture from the heliostat being calculated (i.e., that the flux
point is not shadowed by the outside of the cavity). Flux maps at or in front of
the aperture are assumed not to have any aperture shadowing. In addition, for
multiple aperture cavities, DELSOL allows the user to specify the aperture(s)
through which the reflected sunlight can reach the flux surface (ICAVF, namelist
NLFLUX). This latter feature can be used to account for the possibility that the
flux surface may be blocked by the internal structure of the cavity.
The flux from a heliostat is found by projecting the flux point along the -t^ direction
(i.e., back towards the heliostat) to the image plane whose origin is the
aimpoint on the receiver. The Hermite series (Equation 1II.F-1) is evaluated and
multiplied by -f-i, where is the normal of the flux surface at the flux point. For
multiple aimpoints this procedure is repeated for each aimpoint. To represent
accurately the flux from a zone’of heliostats, the code uses the average
flux from a number of heliostats spanning the zone, depending on image
size, and not just a single heliostat located at the field point. The flux
from a field of heliostats is obtained by summing the flux from the zones within
the field. The single time of the year at which the flux is calculated is determined
by the user with the variable IFXOUT(I,J), where I=l, NYEAR and J=1, 16 to
describe the time during the day. The appropriate values for I and J to correspond
to a given day and time of year are shown in Table 111-1. Only one value
in the IFXOUT array should be nonzero during any single DELSOL calculat
ion.
All flux density distributions for systems previously optimized by DELSOL
are calculated using the value REFSOL as the insolation incident onto the he-
liostats. At times during the year when the insolation is not equal to REFSOL,
the actual flux densities will be different from those values which are printed in
the output by the ratio of the actual insolation to REFSOL. However, flux maps
for systems which are input by the user will use the actual insolation for the re-
quested time.
ll.G-I. Specification of Flux Point Positions-The flux points are specified by
giving their location in ground based coordinates relative to the receiver “cen-
ter’’ and by defining the direction of the outward normal on the side of the sur-
face upon which the flux is incident. The receiver center (XFC=YFC=ZFC=O,
namelist NLFLUX) is on the tower centerline a distance THT (namelist REC)
above the plane of the heliostat pivots. This is at the same elevation as the mid-
dle of an external receiver or the middle of a cavity aperture or flat plate receiver.
DELSOL provides four options for generating a 2-D grid of equally spaced flux
points: (1) points on the outer surface of a vertical cylinder (IFLAUT=l); (2)
points on the inner surface of a hollow vertical cylinder (IFLAUT=2); (3) points
on one side of an arbitrarily oriented plane (IFLAUT=S); or (4) a code-generated
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