A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
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108<br />
other apertures (<strong>for</strong> a multiple cavity receiver) will be fixed by the val-<br />
ues of RX2TRX, RXSTRX, and RX4TRX. The second receiver variable<br />
to be varied when IOPTUM=2 is the receiver diameter, W as defined in<br />
Section 1I.E. Since the depth of the Ith cavity is proportional to W (RW-<br />
CAV(I), Namelist REC), the second receiver variable also varies the cavity<br />
depth. There are NUMHTW (520) discrete equally spaced values of the<br />
width, W, from a minimum of HTWST meters to a maximum value of<br />
HTWEND meters. W, and thus the cavity depths W x RWCAV(I), is de-<br />
termined almost entirely by receiver flux limits, if any. There is a slight<br />
per<strong>for</strong>mance disadvantage, due to receiver losses, of making the cavity<br />
deeper <strong>for</strong> a fixed aperture size. There is also a cost penalty <strong>for</strong> making<br />
the cavity deeper, since the size of the heat exchanger surface grows as<br />
discussed in Section V.A-5(b). There<strong>for</strong>e, DELSOL will not increase the<br />
depth of the cavity above the minimum value allowed in the optimization<br />
search (HTWST x RWCAV(1)) unless it is <strong>for</strong>ced to by a flux constraint<br />
on the heat absorbing surface. Note that the flux calculation is done sep-<br />
arately from the power calculation and does not affect the power calcula-<br />
tion in any way, since the power calculation is done at the aperture. Thus,<br />
other than a slight change in receiver losses, changing the cavity depth<br />
will not affect the receiver power, but it will directly affect the fluxes inci-<br />
dent on the heat absorbing surface.<br />
If NUMREC or NUMHTW is set to 1, then the appropriate value of<br />
RX(1) or W as defined in the previous REC Namelist will be used, rather<br />
than using the limits defined above.<br />
The second step in optimizing a cavity is to fine tune the width and aspect<br />
ratio of the apertures by specifying IOPTUM=l. During this optimization<br />
step the user should set the parameter W in the Namelist REC<br />
to the optimum W found in the first step. With IOPTUM=l the first receiver<br />
variable is again the width of the first aperture, RX(1). However,<br />
the second receiver variable is now the dimensionless aspect ratio of the<br />
aperture, RY (1) /RX( 1). There are NUMHT W (520) equally spaced values<br />
of the aspect ratio from a minimum value of HTWST to a maximum<br />
value of HTWEND. As mentioned be<strong>for</strong>e, if NUMREC or NUMHTW is<br />
set to 1, then the appropriate value of RX(1) or RY(1) as defined in the<br />
previous namelist will be used, and the limits described here will be ignored.<br />
Flux values should be checked during both steps of optimizing a cavity<br />
receiver as described above. In the first step, cavity depth directly affects<br />
flux, while having a different aperture in the second step could affect aim<br />
strategies and thus the flux incident on the absorber surface. This second<br />
effect should be minor, however, since the aperture area will probably stay<br />
nearly constant, although the aperture shape could change.