Optimization of disk generator performance for base-load power plant systems applications Page: 4 of 9
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Irjr. a Swirl Ratio
Figure Jl. Enthalpy Extraction Length (25% extraction)
vs Initial Suirl Ratio. P0=S atm., Tq=2879 K.
Ba7 T. E=-12 kV/m, o=l.33°07.
V X 10
Figure 5. Electrical Behavior of Segmented Disk.
Inlet: P =7.8 atm.. T=2379 K. H=1.9.
ITW#ls^. ( t DmRLFT Ul»/ I I RAT*. IFF.I
. , . .1
no onsc. TiEKn. uwr - w
Figure 6. 'Channel Enthalpy Extraction and Isentropic
Efficiency vs Thermal Input (from Ref. 6).
III. Closed-Cycle Disk Generator Optimization
Generator Hodel Assumptlons/Formulation
The two-temperature generator model assumptions and
formulation are as follows. The CCD working fluid is
cesium-seeded argon. The channel flow is quasi-one-
dimenslonal and accounts for friction and wall heat
losses (similar to the OCD model). Finite-rate electron
kinetics and energetics are Included for analysis of the
ionization relaxation processes at the generator inlet g
and for the cases where the seed becomes fully ionized.
The effective conductivity and Hall parameter are -
determined from reduction formulae developed by Louis.
These formulae (whi^g ^ije comparable to those used in
linear ECAS studies *' ) are applicable for near iso-
tropic turbulence and express the effective properties
in terms of the ideal values and a plasma turbulence
parameter. The effects of molecular impurities or
contaminants are incorporated in the model, with
separate collisional loss factors for each species
(required to more fully model the recombination rate
constants and energy averaged collision frequeijqy).
Cross-section data given by Spencer and Phelps ‘ are
The model formulation consists of solving six
conservation equations (three for heavy gas particles
and three for the electron species). In additiun, a
constraint equation, the equation of state, and Ohm's
Law are required to solve for the nine dependent v— i-
ables: n, Ne, UR, U . ER, T , Tg, p. z; that is. the
neutral gas and electron density, radial and azimuthal
gas velocity, electric field, heavy gas and electron
temperature, pressure and channel height. Tne
constraint equation Is handled by requiri.-g the
generator to operate, at each radial position, at the
local maximum electrical efficiency. Operation close to
maximum efficiency is particularly important for closed
cycle generators, since the performance is limited
primarily by the effective Hall parameter, 3 , rather
than by the Hall field constraint (as is the'case for
□CD). Ionization instabilities which lead to plasma
turbulence are minimal in OCD generates, but must be
considered in the nonequilibrium case.
Since there is a close coupling and interaction
between the generator suboptimization and the system
constraints, a simplified argon and steam loop cycle is
incorporated in the model. The system includes pressure
losses for the generator, nozzle, diffuser and heat
exchangers: Table 3 gives the efficiencies for the argon
and steam loop components used. The generator heat loss
is neglected since it is assumed that the channel walls
operate at the adiabatic recovery temperature. The heat
source loop is handled by the assumption of a heat
source efficiency (of 88%), and air compressor and feed
pump work are assumed to be about 5% of the argon com-
pressor work. The system is U3ed primarily to establish
the "match" point location relative to the generator
exit conditions. This is discussed more fully below.
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Teare, J.D.; Loubsky, W.J.; Lytle, J.K. & Louis, J.F. Optimization of disk generator performance for base-load power plant systems applications, article, January 1, 1980; United States. (digital.library.unt.edu/ark:/67531/metadc1072724/m1/4/: accessed February 18, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.