Discussion of magnetohydrodynamic induction generator examines the machine in detail and materials problems influencing its design. The higher upper-temperature limit of the MHD system promises to be more efficient than present turbine systems for generating electricity

Jackson, W. D.

Pierson, E. S.

English

NASA Technical Reports Server

July 1969
	
Brief 69-10255 
•
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. 
Channel-Wall Limitations in the Magnetohydrodynamic Induction Generator 
.
The materials problems influencing the design and 
performance of the magnetohydrodynamic (MHD) 
induction generator have been discussed (1). A prev-
ious analysis of the machine is reviewed and extended 
to include electrically conducting channel walls and 
thermal insulation. The infinite-length machine is 
examined in detail, with both an approximate analysis 
to show the general behavior, and an exact solution to 
provide numerical data. An approximate analysis of 
one model of a finite-length generator is also pre-
sented. 
The MHD generator system promises, because of 
its higher upper-temperature limit, to be more effi-
cient than the present turbine systems for generating 
electricity, either alone or in combination with a 
steam, system as a topping cycle; also it appears to be 
attractive for space and other special applications. 
This superiority of the MHD system has been demon-
strated in various published analyses. However, the 
properties of its materials may reduce its perform-
ance; the importance of these properties was realized, 
and the analysis includes a detailed study of them and 
their effect on the generator's performance. 
The MHD generator system analyzed uses an alkali 
metal as the working fluid at temperatures above 
1,600°F in a condensing or Rankine cycle. The alkali 
metal is pumped through a channel by the vapor, the 
result being either a pure liquid or a liquid-vapor 
mixture as the working fluid in the generator. The 
channel is inside a magnetic core containing a poly-
phase winding that produces a traveling magnetic 
field in the fluid. The high-velocity fluid moves at a 
velocity greater than that of the traveling magnetic
field; so that the fluid does work on the magnetic field 
and thereby generates electrical power. 
The analysis formulates the design of the MHD 
generator. The requirements of the properties of the 
materials of both the electrically conducting refractory 
metal liner, in contact with the hot, high-velocity, 
alkali-metal working fluid, and the thermal insulation 
to protect the magnetic core are considered. The 
matter of these requirements versus the available 
properties is a vital factor in the ultimate efficient 
operation of an MHD power system. 
The power flow between the field structure and the 
fluid is used for determination of the effect of the 
conducting wall (metal liner), with practical properties 
of the materials and dimensions of the machine. It is 
shown that the wall has to be very thin for acceptable. 
performance by the generator and that this require-
ment raises severe structural problems. The effect of 
the thermal insulation is determined to be small. 
Reference: 
E. S. Pierson and W. D. Jackson, ANL-7148 (Ar-
gonne National Laboratory, March 1966) (available 
from CFSTI, Springfield, Va. 22151, at $3.00—
microfiche $0.65); W. D. Jackson and E. S. Pierson, 
in Proc. J.A.E.E. Symp. Salzburg July 1966 
(I.A.E.E., Vienna, Austria, 1966), vol. 2, pp. 889-
902. 
Notes: 
I. Manufacturers of power generation and distribu-
tion equipment may be interested.
(continued overleaf) 
This document was prepared under the sponsorship of the Atomic 	 liability resulting from the use of the information contained in this 
Energy Commission and/or the National Aeronautics and Space document, or warrants that the use of any information, apparatus, 
Administration. Neither the United States Government nor any per- 	 method, or process disclosed in this document may not infringe pri-
son acting on behalf of the United States Government assumes any vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000255 2020-03-16T17:48:57+00:00Z
2. Inquiries may be directed to: 	 - 
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B69- 10255 
Source: (1) W. D. Jackson of
Massachusetts Institute of Technology
under contract to
Argonne National Laboratory 
(2) E. S. Pierson
Reactor Engineering Division
(ARG- 10128)
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 69-10255	 Category 02


Channel-wall limitations in the magnetohydrodynamic induction generator

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