Note: Descriptions are shown in the official language in which they were submitted.
1~8860~3
; BACKGROUND OF THE INVENTION
:
This invention relates to magnetohydrodynamic methods and
generators which supply an EMF force derived from mutual actions of
conductive fluids flowing wlthin magnetic fields. "MHD" is an ab-
breviation for the term magnetohydrodynamic.
More particularly, the present invention is concerned with
combustion fired MHD power systems the working fluid of which con-
sists of combustion products resulting from a combustion of cheap
fuels such as coal, oil, natural gas, carbon monoxide, char and the
;~ 10 like with an oxidant such as air. The efficiency of such MHD power
. . .systems is the greater the higher the electric conductivity of their
~; working fluids. Conductivity, in turn, is dependent on ionization.
'`'~ Unfortunately, combustion temperatures of conventional combustibles
;,~, .
~ are not high enough to obtain a suitable ionization of a working fluid
;~ consisting of the products of such combustion. Therefore, it has
,~ ,
been tried to increase working fluid ionization in various manners
~;;' such as by virtue of external energy, electric arc discharges, and
seeding the working fluid with an alkali metal such as cesium or
potassium.
~; 20 Also shock waves are suitable to improve ionization since
they are directional and, therefore, generate translation and dis-
~`. sociation terms in the direction of progress. Such means are described
,~ in British Patent Specification No. 1,296,309, University of Utah,
''?'~" published November 15, 1972.
:~ Shock waves have been generated in combustors of MHD gen-
' erators also by feeding them with explosives and detonating the latter
periodically whereby high voltage electrical impulses in a range of
` 10 to 20 kilovolts could be obtained. Such MHD-generators are dealt with
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by Ernest H. Jager and Franz R. Thomanek in their article
"Untersuchungen uber sprengstoffbetriebene MHD-Generatoren" in
Vol. 25 1974 Journal of Applied Mathematics and Physics (ZAMP)
pp. 47 to 54. However, explosives are relatively expensive for
being used as fuels. ~oreover, explosion time periods are too
short for the explosive being thoroughly combusted whereby
energy transformation is rendered incomplete with inevitable
energy losses and low efficiency. Thus, the use of explosive
fired MHD generators is, at present, economically unjustified.
The present invention is thought to be an improvement
over such systems in that the principle of increasing ionization
by means of shock waves is employed in connection with conven-
tional and, thus, low cost fuels.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided
a method of generating electric energy magnetohydro-dynamically
comprising the steps: combusting a fuel material in a combustion
chamber; generating shock waves at the termination of the
combustion of said fuel material in the combustion products
thereof; directing said shock waves within said combustion
chamber and guiding them several times through said combustion
products by reflecting them; and supplying said combustion
products ionized several times by said shock waves into an MHD-
generator.
In accordance with another aspect of the invention
there is provided an MHD power system comprising an MHD generator;
a combustion chamber in the form of a cavity resonator to burn
fuel with oxidant and supply combustion products thereof to said
generators; a fuel supply inlet in said combustion chamber; fuel
supply means connected to said fuel supply inlet; an explosive
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supply inlet in said combustion chamber; explosive supply means
connected to said explosive supply inlet; and explosion
initiating inlet in said combustion chamber; explosion initiating
means connected to said explosion initiating inlet; an outlet
in said combustion chamber for exhausting said combustion pro-
ducts to said generator; sensing means with a signal output in
said combustion chamber for sensing at least one combustion
parameter therein, a control unit with a control signal input
for operating said fuel supply means, said explosive supply
means and said explosion initiating means; said signal output of
said sensing being connected to said control signal input of
said unit.
The invention relates to an improved combustion fired
MHD power system in which shock waves are applied to combustion
products resulting from combustion of conventional fuels.
According to the present invention, in a method of generating
electric energy magnetohydro-dynamically in a combustion fired
MHD power system, first a conventional fuel is combusted to
combustion products, then, with combustion substantially ter-
2a minated shock waves are generated in such combustion productsso as to ioniæe them. Eventually, the ionized combustion
products are exhausted by theirproper pressure and the shock
waves.
The main advantage of the new MHD power system consists
in permitting the use conventional fuels such as coal, oil,
natural gas, carbon monoxide, char etc. since such fuels are
relatively inexpensive and plentiful, and provide
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1(~886~
good possibilities for MHD power systems that are economical. More-
over, such fuels are permitted to burn completely prior to their
being supplied to an MHD generator. Thus, in contrast to explosive
fired MHD generators, no energy losses due to incomplete combustion
will occur. It has been recognized that such combustion products
may be strongly ionized by generating shork waves in them when com-
bustion has substantially been terminated and that by means of using
surprisingly small amounts of explosives which means a likewise low
cost of explosive consumption. Furthermore, relatively slow com-
bustion permits a reliable synchronisation of fuel supply, ignition
combustion, shock wave generation, combustion gases exhaust and
cycle repetitions. Thus, a relatively high efficiency may be obtained
as proved by calculations which permit an estimate of 30 to 40 %.
Such figures are due to shock waves directional and, being directed
so that they greatly enhance the forming of translation and dis-
sociation terms as has been referred to above. Moreover, the shock
waves will cover a path across the region of combustion several times
since longer paths mean greater possibilities for forming of trans-
lation and dissociation terms and, thus, a more effective or im-
proved ionization.
An MHD power system suit3ble for carrying out the above
specified method may comprise a combustor in the form of an acoustic
cavity resonator to burn fuel with an oxidant. The combustor has a
fuel supply inlet which may have fuel supply means connected to it.
An explosive supply inlet in the combustor is connected with an
explosive supply means. Explosion in the combustor is brought about
by explosion initiating means connected with an explosion initiat-
ing inlet in the combustor. Combustion
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products withdraw from the combustor through a combustion
product outlet Gonnectable to an MHD generator. Further_
more, the combustor is provided with feeler means having
a slgnal output. ~he feeler means serves for feeling
one or more parameters of the combustion whioh takes place
in the combustor. Dependent on felt values the feeler means
develops signals;which are received.by a control signal
input of a control uni.t. The control unit controls the
~ operation of various parts of the MHD power system in a
well defined :sequence. More particularly, the fuel
suppl~.means, the explosive supply means and the explosion
initiating means are operated in such manner that, first,
a.predetermined amount of fuel i8 com~pletely burnt where-
after a relatively'small amount of explosive is
supplied and initiated~ For such purpose? the signaloutput of the feeler means.is connected to the control
slgnal input of~the control unit. ::~
; Préferably, the waLls of'the cayity resona~or àre
. represented by paraboloi~ds which faae each other~ ~ith
~ their coneave sides and:cause shock waves to travel ~:
repeatedly aoross:the combustion chamber:of the aombustor.
his..means a~ inoreased length of travel a~d, thereby,~ a
.: moro vigorou~:formlng of translation.and dissociation
: . terms with a aonsequent improvement~of ionization.
;'25 . Mo.reover, such paraboloidic walls ma~ ha~e different ~ocal
~: dista~nes~. Thsn, the pa~raboloid wall:of smsller fooal
: ~ . dlstance will lie oppo8ite to the~combustion products
outlot of the. ¢ombustor. .8uch arrangement permits that- .
'. . tho point of intersection of the longitudinal conter:line
~0 of the combustor with the longitudinal~centor line of~
~the explosive ~supply inlet be pro~eoted into the ¢ombustion ~.
produot~ outlet of the combustor. ~hereby, shoo~ WBVeB ma~
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withdraw from the cavity resonator without suffering noticeable damping.
BRIEF DESCRIPTION OF T~E DR~WINGS
Figure 1 is a schematic diagram of a simple MHD power system
embodying the p~esent invention.
Figure 2 is a longitudinal sectional view of the main con-
structional parts of an exemplified embodiment of the MHD power system
shown in Figure l.
Same reference characters refer to similar details in both
figures and throughout the specification and claims.
Referring to Figure l, reference numerals 10 and 12 designate
a combustor with a combustion chamber 10a and an MHD generator, respect- ;
ively.
The combustor 10 has a fuel supply inlet 14 which has a fuel
supply means 16 such as fuel pump, carburetter, etc. connected to it
by means of a conduit 18. Furthermore, the combustor lO has an ex-
plosive supply inlet 20 which is connected through a conduit 22 to an
explosive supply means 24, e.g. likewise a pump as in case of the fuel
supply means 16. A third orifice 28 in the combustor 10 is closed by
a transparent cover 26 and serves as an explosion initiating inlet 28.
lgnition of the fuel may be brought about e.g. by a plasma -
burner, ignition globe, spark plug or the like. Preferably, however,
a pulsed laser 30 will be employed since it is suitable to initiate an
explosion of the explosive supplied through explosive supply inlet 20
as well. Namely, it has been recognized that laser beams are capable
of initiating explosion of liquid and solid explosives since such
initiation requires 0.1 to 10 calories Joule heat and a power of 0.1 to
10 megawatts, and laser beams readily meet such requirements. Their
: ,-, . .
use as exploder is particularly ad~antageous in the instant case because
of the high accuracy as to the moment of initiating.
Reference numeral 32 designates a feeler within the combustor
lO. Feeler 32 is pro~ided for feeling at least one parameter of com-
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bustion and or developing an electric signal dependent on such parameter.
A signal output of feeler 32 is referred to by reference numeral 32a. -
The combustor lO is also provided with a combustion products
outlet 34 for exhausting such products from the combustor 10 into the
MHD generator 12.
Reference numeral 36 designates a control unit with a control
signal input 36a and a pair of control signal outputs 36b and 36c. The
control signal input 36a is connected with the signal output 32a of the
combustion parameter feeler means 32 through path 38 while control signal
outputs 36b and 36c of the control unit 36 are connected to the fuel
supply means 16 and the explosive supply means 24 via paths 40 and 42,
respectively.
Explosive supply means 24 is in operational connection with
laser 30 through path 44.
It will be seen that, in the instant case, on the one hand,
laser 30, explosion initiating inlet 28 and combustion products outlet
34 lie along a same axial center line A-A. In a similar manner, ex- ~ -
plosive supply inlet 20 lies along a center line B-B which is transverse
of center line A-A. Such mutual arrangement of center lines A-A and B-B
results in a readily distinguishable point of intersection the sig-
nificance of which will be apparent hereinafter.
Furthermore, likewise in the instant case, combustion chamber
lOa is confined by mutually opposite paraboloidal walls 46 and 48.
Moreover, with the represented embodiment, the paraboloid walls 46 and
48 have diferent focal distances fl and f2 marked by focal points Fl
and F2, respectively, the paraboloidal wall 46 of smaller focal distance
fl lying opposite to the outlet 34. While mutually opposite paraboloidal
walls 46 and 48 are particularly suitable to focus rays reflected by
them, selecting different focal distances fl and f2 in the described
manner permits to project the image of the point of intersection of
axial lines A-A and B-B into the combustion products outlet 34 ~as shown
in Figure 2) the significance of which has already been pointed out.
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The MHD generator 12 is of a ~ se known construction. It com-
prises a Laval nozzle 50 a difusor portion of which carries a magnetic
lens system 52. Electrodes 54a and 54b isolated from Laval nozzle 50
lie in an electric circuit 56 comprising magnet coils 58 and 60 of the mag-
netic lens system 52, and a load 58.
Constructional details of the new MHD power system are portrayed ;
in Figure 2. The combustor lO comprises a pair of half casings 64 and 66
which enclose the combustion chamber lOa described above. Hole 68 serves
for receiving a feeler 32 mentioned in connection with Figure l. Explosive
inlet 20 has a duplicate in the form of a hole 70 the provision of which
may be justified e._. by reasons of easier mounting. Unemployed inlets
or holes are closed e.g. by not ropresented plugs.
Reference numerals 72 and 74 designate screws by which half
casings 64 and 66 are fixed in their mutual operative positions.
The M~D generator 12 is fixed to the combustor 10 by a threaded
connection referr~d to by reference numeral 76. The electrodes 54a and
54b are electrically separated from the metallic body o the MHD generator
by insulator 78.
In operation, fuel supply means 16 ~Figure 1) delivers fuel,
e.~. petrol, Diesel oil or coal dust through conduit 18 into the combustion
chamber lOa of combustor 10. Amount and moment of fuel delivery are con-
trolled by control unit 36. Seeding the working fluid may be carried out
by admixing an alkali metal such as cesium or potassium to the fuel prior
to or during its delivery. Oxygen or oxygen carriers such as air may be
added too.
The fuel supplied into the combustion chamber lOa will be ignited
by the pulsed laser 30 in a maM er known ~ se and completely combusted.
After complete combustion has taken place and a corresponding signal has been
given by feeler 32 to control unit 36, the latter triggers the explosive
supply means 24 which delivers a predetermined amount of explosive through
inlet 20 between focal points Fl and F2. At that moment the pulsed laser
30 which now works as an exploder sends a laser beam to the explosive in the
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combustion chamber lOa whereby oxplosion is initiated.
The exploslon in the combustion chamber lOa entails a shock wave
in the combustion products which travels several times between the parab-
oloidal walls 46 and 48, as shown in Figure 2 by broken lines, thereby
causing strong ionization of the combustion products before they are ex-
hausted through the combustion products outlet 34 into the Laval nozzle 50.
The ionized combustion products withdraw rom the combustion
chamber lOa at very high flow velocities and pass through a transverse
magnetic field generated by the magnetic lens system 52. By that transverse
magnetic field the ionized combustion products impinge on the electrodes
54a and 54b between which they create a voltage difference. Thus, a
corresponding current will flow in the electric circuit 56 and operate
the load 62.
The control unit 36 ensures that the above described operational
process will periodically be repeated which results in a sort of ripple
current in the electric circuit 56.
It will be apparent that the invention permits to build MHD
generators which show a combination of all advantageous features of prior
devices and methods without their drawbacks: cheap fuels may be employed
and completely combusted. An overwhelming portion of useful heat energy
is released from ~uch cheap combustibles. At the same time, shock waves
may be generated for ionizing, accelerating and focussing combustion
products by means of small amounts of explosives and, thus, at relatively
low expenses. ~he partial processes of energy transformation follow one
another in co-ordinated sequence which means ldeal operational circumstances
and, thereby, attainment of high efficiencies in the range of 30 to 40 % as
shown by calculations.