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

III. G-1. Atmospheric Attenuation: Heliostat to Receiver-The seasonal varia-
tion of atmospheric attenuation at ground level for the test locations of Barstow
and Albuquerque (based on constant visibility) is reported to be small (Reference
26) and is ignored in DELSOL. However, the effects of local altitude and visibility
are not ignored. DELSOL offers two options, identified by the user’s choice of the
parameter IATM in the Namelist BASIC:
1) IATM = 0 Clear day, Barstow (visibility = 23 km)
LOSS (%) = 0.6739 + 10.46 R - 1.70 R2 + 0.2845 R3 (I1I.G - 1)
(Reference 21)
2) IATM = 1 Hazy day, Barstow (visibility = 5 km)
Loss (%) = 1.293 + 27.48 R - 3.394 R2 (Reference 21) (III.G - 2)
3) IATM = 2 User defined attenuation
Loss (fraction) = ATMl+ATMBxR
+ATM3 x R2+ATM4 x R3 (III.G - 3)
where R is the slant range (heliostat to receiver) in km. The first two equations
are graphically presented in Figure 111-2. Similar equations for Albuquerque are
also given in Reference 26, but these are not currently available as an option in
the code. The default choice is the clear day model:
IATM = 0
III. G-2. Mirror and Receiver ReflectivittWhile it is know that mirror re-
flectivity can degrade between washings (Reference 27), it is assumed constant
along with receiver re-reflectivity. Default values are (namelist variable name is in
parentheses) :
Mirror reflectivity (RMIRL) = 0.91 (glass, average between washings;
Reference 28)
Receiver absorption (RRECL) = 0.965 (=1.0 - receiver reflectivity; default
value for external molten salt
design)
III. G-3. Radiation and Convection Losses from the Receiver- Two options for
calculating receiver losses are available in DELSOL, depending on the choice of
the variable IRADFL (Namelist NLEFF). In one case, losses are calculated di-
rectly dependent on a set of temperature and weather assumptions, while in the
other case receiver efficiency is scaled with receiver area (external or billboard