  We model the infrared (IR) emission from the double-ring disk of HD 141569A,
using a porous dust model that was previously shown successful in reproducing
the spectral energy distributions (SEDs) of the disks around $\beta$ Pictoris
and HR 4796A. The dust consists of either unaltered or highly processed
interstellar materials and vacuum with a volume fraction of ~90%. Together with
a population of polycyclic aromatic hydrocarbon (PAH) molecules of which a
large fraction is charged, the porous dust model made of coagulated but
otherwise unaltered protostellar interstellar grains provides an excellent fit
to the entire SED from the mid-IR to millimeter wavelengths including the PAH
mid-IR emission features. The nondetection of the 21 micron crystalline
silicate feature predicted from the porous dust model composed of
highly-processed grains (mainly crystalline silicate dust) imposes an upper
limit of ~10% on the mass fraction of crystalline silicates. Spectroscopic and
broadband photometric predictions are made for SIRTF observations which will
provide further tests of the applicability of the porous dust model to
circumstellar disks.
