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

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other apertures (for a multiple cavity receiver) will be fixed by the val-
ues of RX2TRX, RXSTRX, and RX4TRX. The second receiver variable
to be varied when IOPTUM=2 is the receiver diameter, W as defined in
Section 1I.E. Since the depth of the Ith cavity is proportional to W (RW-
CAV(I), Namelist REC), the second receiver variable also varies the cavity
depth. There are NUMHTW (520) discrete equally spaced values of the
width, W, from a minimum of HTWST meters to a maximum value of
HTWEND meters. W, and thus the cavity depths W x RWCAV(I), is de-
termined almost entirely by receiver flux limits, if any. There is a slight
performance disadvantage, due to receiver losses, of making the cavity
deeper for a fixed aperture size. There is also a cost penalty for making
the cavity deeper, since the size of the heat exchanger surface grows as
discussed in Section V.A-5(b). Therefore, DELSOL will not increase the
depth of the cavity above the minimum value allowed in the optimization
search (HTWST x RWCAV(1)) unless it is forced to by a flux constraint
on the heat absorbing surface. Note that the flux calculation is done sep-
arately from the power calculation and does not affect the power calcula-
tion in any way, since the power calculation is done at the aperture. Thus,
other than a slight change in receiver losses, changing the cavity depth
will not affect the receiver power, but it will directly affect the fluxes inci-
dent on the heat absorbing surface.
If NUMREC or NUMHTW is set to 1, then the appropriate value of
RX(1) or W as defined in the previous REC Namelist will be used, rather
than using the limits defined above.
The second step in optimizing a cavity is to fine tune the width and aspect
ratio of the apertures by specifying IOPTUM=l. During this optimization
step the user should set the parameter W in the Namelist REC
to the optimum W found in the first step. With IOPTUM=l the first receiver
variable is again the width of the first aperture, RX(1). However,
the second receiver variable is now the dimensionless aspect ratio of the
aperture, RY (1) /RX( 1). There are NUMHT W (520) equally spaced values
of the aspect ratio from a minimum value of HTWST to a maximum
value of HTWEND. As mentioned before, if NUMREC or NUMHTW is
set to 1, then the appropriate value of RX(1) or RY(1) as defined in the
previous namelist will be used, and the limits described here will be ignored.
Flux values should be checked during both steps of optimizing a cavity
receiver as described above. In the first step, cavity depth directly affects
flux, while having a different aperture in the second step could affect aim
strategies and thus the flux incident on the absorber surface. This second
effect should be minor, however, since the aperture area will probably stay
nearly constant, although the aperture shape could change.