Two-phase flow generator cycle of a magnetohydrodynamic /MHD/ generator uses a working fluid which is compressible and treated as an expanding gas. The two-phase mixture passes from the heat source through the MHD generator, where the expansion process takes place and the electrical energy is extracted

Petrick, M.

English

NASA Technical Reports Server

June 1969
	
Brief 69-10162 
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ICY C
AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Magnetohydrodynamic Generators Using Two-Phase Liquid-Metal Flows 
Diffuser 
Reactor 
Figure 1 One-component two-phase cycle 
The limits of performance of two-phase magneto-
hydrodynarnic (MHD) liquid-metal generators have 
been explored experimentally over extended param-
eter ranges, and preliminary data are reported (1). 
Systems incorporating direct-energy-conversion MHD 
generators, coupled to nuclear reactors and conven-
tional steam bottoming plants, are expected to lead to 
overall cyclic efficiency of about 50% and so to lower 
costs of electric power. The generators discussed (1) 
can operate at high efficiencies—about 70%. 
In contrast to a Rankine cycle, which employs the 
vapor phase as the working fluid, liquid-metal MHD 
cycles must be designed for transfer of the thermal 
energy of the vapor phase into kinetic energy, or stag-
nation head, of a fluid of sufficient electrical conduc-
tivity to pass through a MHD generator. This con-
straint in design has given rise to many schemes from 
which four basic cycles have emerged: (i) the sepa-
rator cycle, (ii) the condensing-injector cycle, (iii) 
the multistage cycle, and (iv) the two-phase-generator 
cycle (Fig. 1). 
These four cycles have two underlying philosophies. 
In the first three, MHD generators operate on kinetic 
energy deriving from the conversion of thermal energy 
prior to entry into the generator; a vapor is used to 
accelerate a liquid, and then the vapor is either sepa-
rated or condensed; the generation of electric power 
from the liquid stream is a separate operation. In the
two-phase-flow generator cycle studied at Argonne 
National Laboratory the working fluid is compressible 
and treated as an expanding gas; the thermal-to-elec-
tric conversion proceeds in a single interaction region. 
The expansion process is similar to that occurring in a 
plasma generator. The liquid-acceleration cycles are in-
herently friction-limited and capable of only moderate 
performance in terms of efficiency, but the two-phase 
cycle offers the prospect of relatively highly efficient op-
eration; it promises to be highly competitive with not 
only turbomachinery but also other converters of 
energy. Either a one- or two-component version of the 
cycle is possible. Basically .the two-phase mixture passes 
from the heat source through the MHD generator, 
where the expansion process takes place and the elec-
trical energy is extracted. 
The operation of such a two-phase generator is con-
fined to a specific quality range; however, the feasi-
bility of a second type of generator, a film-flow 
generator, that potentially can accommodate higher-
quality mixtures has also been established. The film-
flow generator, if placed immediately adjacent to the 
separator in the separator cycle, could improve over-
all efficiency by eliminating the transitional losses; or 
it can combine the functions of separator and gen-
erator. The limits of performance of these two gen-
erators have been examined experimentally over ex-
tended ranges of parameters. (continued .overleaf) 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
liability resulting from the use of the intormation contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000162 2020-03-16T17:39:49+00:00Z
Reference: 
M. Petrick, SM1741196 (Argonne National Lab-
oratory, 1968); J.A.E.A. Symp. Magnetohydrody- 
narnic Electric Power Generation Warsaw July 1968 
(SM-107120), pp. 1-24. 
Notes: 
1. This information may interest researchers in the 
development of power generation. 
2. Inquiries may be directed to: 
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B69-10162
Source: M. Petrick
Reactor Engineering Division
(ARG-10168)
Patent status: 
Inquiries concerning rights for commercial use of 
this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439
. 
. 
. 
Brief 69-10162	 Category 01


Magnetohydrodynamic generators using two-phase liquid-metal flows

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