US3432694A - Magnetohydrodynamic generator - Google Patents

Description

F'EPBEOZ R. BIDARD Marsh 11, 169

MAGNETOHYDRODYNAMIC GENERATOR Sheet of Filed July 14, 1966 R. BIDARD March 11, 1969 MAGNETOHYDRODYNAMI C GENERATOR Sheet Filed July 14, 1965 March 11, 1969 Filed July 14, 1966 R. BIDARD 3,432,694

MAGNETOHYDRODYNAMIC GENERATOR Sheet 4 of 4 Rene Bldamd.

United States Patent U.S. Cl. 310-11 '7 'Claims rm. c1. H02u 4/02 This invention relates to so-called magnetohydrodynamic devices wherein an electronically conductive fluid is caused to flow through a magnetic field arranged normal to the path of fluid flow and wherein electrical power is either taken out through associated electrode means or put in depending upon whether the device is operated as an electric generator or as a compressor. The electrically conductive fluid can be arranged for a single pass through the device, or it can be arranged to flow in a repetitive manner i.e. re-cycled over a closed loop.

It is known to obtain magnetohydrodynamic loops by means of emulsions of gas in an electrically conductive liquid, which can be subjected completely to a magnetic field and which comprise, in series over the liquid flow path, a region where the emulsion works, a region where separation of the liquid and of the gas is produced, which is drawn off through a suitable pipe, a region where the liquid is restored to its original pressure, and finally a region where the emulsion is formed again by injection of gas bubbles into the liquid.

Depending on the case, these loops can either generate electricity on the whole, in which case the gas expands during its passage, or they consume electricity on the whole, in which case one obtains a compression of the gas.

An inconvenience of these loops is that the expansion (or compression) ratios which can be obtained in a single loop are limited by the necessity of preserving a suitable ratio, both at the inlet of the gas and at the outlet, between the volume fiow of the conducting liquid (which is constant along the loop) and that of the gas (which is a function of the pressure).

It is known that if the vapor pressure of the liquid is not negligible as compared with the gas pressure, the heat brought about by evaporation or condensation of this vapor must be taken into account, which makes it desirable on the one hand, to effect at least the last part of the expansion at stepped temperatures, and on the other hand, to provide these succession of steps with an exchange of heat that may perform, thanks to a suitable external heat exchanger apparatus, the reheating of the incoming high pressure cold gas with heat taken off from the expanding hot gas.

Finally, measures must be taken to recycle the flow of condensed liquid toward the regions where evaporation is produced.

The object of the present invention is to provide novel solutions for these various difficulties, separately or in combination, and in a manner which is as simple as possible.

It is characterized in that the transformation of energy is distributed over two or more loops which evolve each 3,432,694 Patented Mar. 11, 1969 at a substantially constant temperature and between two pressures, the low pressure of one loop being equal to the high pressure of the other, with the exception of a small amount used to effect the transfer of the gas from one loop to the other, the temperatures of at least some loops being regulated by the injection of conductive liquid, either cold or hot, into suitable regions of these loops.

Various methods of carrying out the invention are described below by way of non-limiting examples with reference to the attached schematic drawings wherein:

FIG. 1 represents the prior art;

FIGS. 2 to 7 show various manners of obtaining the transfer of the gas between the several loops;

FIG. 8 shows a generator with gas transfer zones and tengperature regulation by injections of conductive liquid; an

FIG. 9 is a diagram showing the function of the generator of FIG. 8.

The same reference numbers are used in all figures to designate the same elements or parts of elements of the magnetohydrodynamic apparatus, namely; the inlet pipe 1 for the compressed hot gas, the emulsifier 2, the region 3 where the emulsion works, the separator 4, the gas outlet pipe 5, and the region 6 where the liquid is restored to its initial pressure. The device producing the magnetic field is not represented nor are the electrodes by which energy is taken out or put in.

FIG. 1 shows a loop according to the prior art in which the conductive liquid circulates in a closed circuit. In the part 3 of this loop is effected the transformation of energy by a magnetohydrodynamic effect applied to an emulsion formed at 2 and eliminated at 4.

According to the invention, this energy transformation is now distributed over several loops .at decreasing pressures, and the gas is transferred from one loop to the next under the effect of a suitable pressure difference.

A simple means of obtaining this transfer, while maintaining the liquid flow in each loop substantially selfcontained, with the exception of the adventitious recycling flow, if any, consists in establishing concentric loops presenting .a communication between them in a curve with such a radius that suflicient pressure gradients are established; the bubbles pass then from the outer loop to the inner loop, while the liquid flows are substantially kept self-contained in each of these loops.

A very great advantage of such a device with regard to that in which the gas is separated from the first loop and re-injected into the second is that a separation loss, plus an emulsion loss are replaced by a transfer loss, which is very likely much smaller than the sum of the first two losses.

Another great advantage of such a device is that the liquid flows of the plurality of loops can difler from each other, and consequently can be adapted to varied volumes of the gas flows which circulate in each of these loops.

If the transfer of the bubbles must be accelerated, it is permissible, without departing from the spirit of the invention to arrange, in the transfer zone, auxiliary expedients, for example, suitable guide blades or vortex rings.

FIG. 2 shows a simple embodiment of the invention comprising one loop A and another loop B inside the former. The gas enters the outer loop A through a pipe 1 and an emulsifier 2 an dissues from the inner loop B through a separator 4 and a pipe 5. Between these two loops A and B there is connection 7, the so-called transfer zone, which acts both as a bubble separator for the loop A and as an emulsifier for the loop B. It is to be observed that the gas has finally worked twice before it is separated by the separator -4, and sent into the res-t of the cycle. It is also to be noted that both in FIG. 1 and in FIG. 2 and the following figures, the separators 4 have been represented in a simple form, with a plane flow, which is possible from the moment on when the separation can be effected in a half-turn, which is the case.

One can also provide, as shown in FIG. 3, a third loop C inside the second loop B, which communicates with it in the same manner as the second loop B of FIG. 2 with the first loop A, that is, through a connection 7 forcing the bubbles to separate from the second loop to be transferred to the third. One can thus arrange, one inside the other, as many loops as described operating at stepper pressures. The bubbles traverse then this assembly, describing in general a sort of centripetal spiral, borrowing a part of each of the successive loops. In FIG. 3, however, the structure consists of only three loops, and on the third has been represented a separator 4 permitting gas extraction. Depending on the configurations given to the various channels, particularly in regions 3 and 6, these different magnetohydrodynamic loops can either be gas expanding, i.e., generating electric power or gas compressing, i.e., consuming electric power.

It is preferable, in order to avoid magnetohydrodynamic losses which are produced at the inlet or outlet of a flow of conductive liquid inside or outside a magnetic field, to locate the assembly of all loops thus connected completely within one and the same magnetic field. In this case the various loops are all naturally connected electrically in series.

The loop assemblies represented in FIGS. 2 and 3 comprise a single gas inlet, and a single gas outlet, and the gas traverses thus in series all loops of each assembly in a single path. But one can also provide, without departing from the spirit of the invention, series-parallel combinations of the gas flow as well as from an electrical point of view.

FIG. 4 shows a system with two loops in series for the expansion, or compression, of the gas, comprising in parallel two inlets and two outlets, the whole in the same plane, each loop being then actually double and formed, over the path of the conductive liquid, of two complete systems in series. This FIG. 4 shows in fact that the outer loop A comprises two gas inlets 1, two emulsifiers 2, two emulsion channels 3, two transfer zones 7 and two liquid channels 6, the whole in series over the liquid flow. The inner loop B comprises two transfer zones 7, in common with the loop A, two emulsion channels 3, two separators 4, two gas out-lets 5 and two liquid channels 6, the whole in series over the liquid flow.

But one can go even further and connect the parallel flows on the gas side and constitute each loop of any number of systems in series over the liquid flow of the said loop, each comprising a transfer zone 7 for the entering gas, an emulsion channel 3, a transfer zone 7 for the issuing gas, and a liquid channel 6. One or the other of the transfer zones can, if desired, be replaced by an emulsifier or by a separator. One constitutes in this way an assembly of loops comprising on the whole three or four etc. gas inlets in parallel each feeding its own emulsifier and as many outlets, each having its own separator, this assembly comprising itself any number of such complex loops arranged in series on the evolution of the gas, through suitable transfer zones.

FIG. 5 shows such an assembly of loops comprising on the whole three gas inlets 1, three outlets 5, formed of four complex loops in series over the gas flows. Each of these four loops is formed from the point of view of the liquid conductor, but comprises in series over this liquid flow three systems each comprising: an emulsion channel '3, a transfer zone 7 communicating with the following loop, a liquid channel 6 where the pressure is restored, and finally a new transfer zone 7 in communication with the preceding loop where the emulsion is reformed.

FIG. 5 represents a combination of concentric loops, which could be called a flat connection. In such a loop connection, the emulsion traverses in fact one, or several, fiat spirals, depending on whether there are one or more inlets and outlets.

However, it is also possible to connect the loops by stacking them one on the other. A particularly interesting case of such an arrangement is that of a large number of simple loops comprising a single emulsion zone, such as that in FIG. 1, and stacked in a cylindrical manner.

It is possible in fact to arrange a very large number of these loops on on the other, displaced by a half turn, and all in series electrically. Such an arrangement is represented schematically in FIG. '6 and in a partially exploded view in FIG. 7 in the case of five stacked loops. In this case the emulsion traverses also a spiral, but placed substantially on a cylinder and no longer in a plane.

This stacking can naturally also be realized with more complex loops comprising several inlets and several outlets.

If one connects in this way a sufficient number of expanding loops with each other, in one way or the other, which are traversed in series by the gas, it is possible to realize a suitable law of evolution of the temperatures of the said loops in the following manner.

The invention provides first of all, an the case of a generating device a heat supply in the loops traversed in the first place by the gas, in order to obtain an expansion close to the isotherm in this region, which is generally desired.

A simple means of realizing this heat supply consists in injecting a certain adventitious flow of hot conductive liquid at one end of the said region, in withdrawing it, (slightly cooled), at the other end, then reheating it in an outside boiler, and so forth. It is advisable to inject this adventitious flow in a direction opposite to the direction of gas flow, i.e. at the outlet of the assembly of loops which constitute the quasi-isothermic region under consideration: because in this way the partial liquid flow issues at the top, compressed at the same time to the maximum pressure, and can thus circulate by itself in the reheating circuit. Its flow can be regulated by a suitable valve. But if it is found of advantage, the adventitious hot flow can also be circulated in the same direction as the gas.

In the second part of the expansion, which must take place preferably at decreasing temperature, particularly in the presence of vapor of the conductive liquid which must be condensed, the invention provides that these temperatures can be established firstly by not supplying heat from the outside to the respective loops, and if necessary by heat-insulating them, one from each other except, of course, in the transfer zones of the gas bubbles. In such a case the overall evolution of the gas will be adiabatic.

Independent of this means, or in combination with it, the invention provides also to inject into the' last loop, at the gas outlet, a new adventitious flow of conductive liquid, but cold this time. In general, a small percentage of the liquid flow of the said loop suffices. This liquid circulates from loop-to-loop, passing through the transfer zones 7, in opposite direction to the gas flow, where it is slowly reheated in contact with the said gas, with a very small temperature difference by borrowing from the gas all the heat that has not been transformed into work by its expansion, and it is finally brought at the highest temperature of the cycle; then one can either extract it from this region, or allow the pressure to rise further at constant temperature in the isothermic part of the expansion described above, and extract it then.

In either case, this adventitious flow functions as an intermediate transfer fluid for the exchange of heat with the compressed and cold gas, which must be reheated; this hot liquid is thus put in contact with the said gas in a suitable external heat exchanger; it issues cold, then it is recycled again as mentioned above in the last loop of the MHD device.

One obtains thus at the same time, and in a very simple manner, three effects: regulating the evolution of the temperature during the expansion, collecting the excess condensate and, finally transmitting heat to the cold gas. One has thus combined in a single machine, an expansion-type generator and a heat exchanger, the latter functioning between the gas and an intermediate heat carrying adventitious liquid flow.

FIG. 8 represents a generator provided with this improvement. Here there is a connection of two simple loops with isothermic expansion, plus four loops with stepped temperatures, realized in the form of a fiat spiral, that is similar to the embodiment of FIG. 3.

FIG. 9 is a diagram equivalent to this assembly. Since one is here concerned with simple loops, only a single gas inlet 1, a single emulsifier 2, a single separator 4 and a single gas outlet 5 are here depicted.

In order to facilitate the understanding, in FIG. 8 is represented the connections of this generator with the other elements of the thermodynamic cycle. The gas issuing from the generator at 5, whose temperature is much lower than the maximum temperature of the cycle, traverses first a low-temperature heat exchanger 8, then a refrigerant 9 and a compressor .10. The compressed gas is then heated in counter-flow in the heat exchanger 8. It passes then into a high-temperature heat exchanger 11, fed with heat from a circuit of conductive liquid, as mentioned above, and is then injected into the generator by the emulsifier 2.

The gas expands then sucessively in two loops, and is kept at a constant temperature equal to the maximum temperature of the cycle, thanks to the recycling of a certain fiow of conductive liquid, in the following manner: an adventitious flow of this liquid is borrowed from the first loop before it enters the emulsifier 2, and this is attained by way of take-off orifice 12. This liquid passes then into a heat source 13, then into a regulating element 14 and is finally injected through an orifice 15 into the liquid flow of the second loop.

The regulating element 14 can be, for example, a magnetohydrodynamic valve, consisting of a series of suitable spaced magnetic poles, arranged along a portion of the duct system, whose exciting current can be varied, thus creating a variable charge loss opposing the movement of the fluid.

The adventitious flow closes again by traversing the transfer zone 7 placed between the first and the second loop in the counterflow, naturally radial, to the gas bubbles, and heats thus also the first loop before it is withdrawnlthrough the orifice 12 and recycled in the heat source 13.

As far as the high-temperature exchanger 11 is concerned, it operates as follows:

An additional adventitious flow is taken from the above mentioned orifice 12, mixed with the former and passes into the heat source .13, then it is separated from the said first flow: it passes then into a regulating element 16, similar to the preceding element 14, then it is conducted into the heat exchanger 11 in counterflow to the gas to be heated. It issues cold and then feeds through the pipe 17 to and through the holes of an arcuate injection tube 18 located in the separator 4. The injection holes permit the liquid to be discharged in the form of drops on the free liquid surface formed-in the said separator.

This arrangement has in fact the advantage of cutting off electrically the circuit of the recycled conductive liquid.

The liquid thus brought to the last loop rises from loop to loop in the entire generator by borrowing successively from all the transfer zones 7 to reissue finally through the orifice 12. This liquid drains all the heat necessary for reheating the cold gas, without hindering in any way the expansion of the gas. This flow collects in addition by itself the liquid condensed in the last loops, those at stepped temperatures and reintroduces it into the first loops, those with substantially isothermic total expansion to compensate for the evaporation which is produced there. However, if it is found of advantage, it is also possible to withdraw it at a lower pressure, just before the isothermic expansion region, and to pass it at this moment into a boiler for reinjection into the said isothermic part.

In conclusion, it is understood that one is here concerned only with an example of the invention which applies also to more complicated cases either that multiple inlets and outlets are provided, or that the connection is effected by stacking and is no longer fiat, etc. It is also understood that the invention also applies to energy transformations by compression of a conductive gas-liquid emulsion.

I claim:

1. In an apparatus of the magnetohydrodynamic type for effecting a transfer of energy from thermal to electrical or vice versa, means establishing a plurality of magnetohydrodynamic loops entirely within a magnetic field and wherein an emulsion of gas in an electrically conductive liquid is caused to flow in said loops, means effecting a transfer of the gas only from one loop to another the energy distribution over said plurality of loops being evolved each at substantially constant temperature and between two pressures, the low pressure of one loop being substantially equal to the high pressure of another loop with the exception of a minor pressure change utilized in the transfer of the gaseous component from one loop to another, and means injecting an electrically conductive liquid into the loops for regulating the respective temperatures thereof.

2. Apparatus as defined in claim 1 for effecting a trans fer of energy wherein separation of the gas from the liquid in one loop, its transfer into the following loop, and its emulsion in the latter loop are obtained by putting the electrically conductive liquids of the respective loops into direct contact in those transfer regions of the loops where the said low pressure of one loop and the high pressure of the adjacent loop prevail.

3. Apparatus as defined in claim 1 for effecting a transfer of energy by expansion wherein the temperature of the first loop or loops is maintained substantially constant by injection therein of a hot conductive liquid.

4. Apparatus as defined in claim 1 for effecting a transfer of energy by expansion wherein the temperature of the last loop or loops are established at decreasing values by absence of circulation of any adventitious flow of hot liquid, said loops being heat-insulating each from the other except in the transfer zones.

5. Apparatus as defined in claim 1 for effecting a transfer of energy by expansion wherein the temperature of the last loop or loops are established at decreasing values by injecting at the gas outlets a cold conductive liquid and circulating it in opposite direction to the gas in each loop and from loop-to-loop up to that where this adventitious flow is extracted.

6. Apparatus as defined in claim 1 for effecting a transfer of energy wherein separation of the gas from the liquid in one loop, its transfer into the following loop and its emulsion in the latter loop are obtained by putting the electrically conductive liquids of the respective liquids into direct contact in those transfer regions of the loops where the said low pressure of one loop and the high pressure of the adjacent loop prevail, and wherein the temperature of the first loop or loops is maintained substantially constant by injection therein of a hot conductive liquid and 7 which circulates from loop-to-loop through said transfer regions.

7. Apparatus as defined in claim 1 for effecting a transfer of energy wherein separation of the gas from the liquid in one loop, its transfer into the following loop and its emulsion in the latter 100p are obtained by putting the electrically conductive liquids of the respective liquids into direct contact in those transfer regions of the loops where the said low pressure of one loop and the high pressure of the adjacent loop prevail, and wherein the temperature of 10 the last loop or loops are established at decreasing values References Cited UNITED STATES PATENTS 3,294,989 12/1966 Eichenberger o- 3l01l 3,385,983 5/1968 Bohn et a1 3l011 DAVID X. SLINEY, Primary Examiner.

Claims (1)

1. IN AN APPARATUS OF THE MAGNETOHYDRODYNAMIC TYPE FOR EFFECTING A TRANSFER OF ENERGY FROM THERMAL TO ELECTRICAL OR VICE VERSA, MEANS ESTABLISHING A PLURALITY OF MAGNETOHYDRODYNAMIC LOOPS ENTIRELY WITHIN A MAGNETIC FIELD AND WHEREIN AN EMULSION OF GAS IN AN ELECTRICALLY CONDUCTIVE LIQUID IS CAUSED TO FLOW IN SAID LOOPS, MEANS EFFECTING A TRANSFER OF THE GAS ONLY FROM ONE LOOP TO ANOTHER THE ENERGY DISTRIBUTION OVER SAID PLURALITY OF LOOPS BEING EVOLVED EACH AT SUBSTANTIALLY CONSTANT TEMPERATURE AND BETWEEN TWO PRESSURES, THE LOW PRESSURE OF ONE LOOP BEING SUBSTANTIALLY EQUAL TO THE HIGH PRESSURE OF ANOTHER LOOP WITH THE EXCEPTION OF A MINOR PRESSURE CHANGE UTILIZED IN THE TRANSFER OF THE GASEOUS COMPONENT FROM ONE LOOP TO ANOTHER, AND MEANS INJECTING AN ELECTRICALLY CONDUCTIVE LIQUID INTO THE LOOPS FOR REGULATING THE RESPECTIVE TEMPERATURES THEREOF.

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