Method and system for converting solar energy into electricity

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ergy and mechanical energy is converted into electrical

METHOD AND SYSTEM FOR CONVERTING energy.

SOLAR ENERGY INTO ELECTRICITY While the invention will now be described in connec tion with certain preferred embodiments with reference

BRIEF DESCRIPTION OF THE PRIOR ART to the following illustrative figures so that it may be The present invention relates to a method and system more fully understood, it is stressed that the particulars for converting solar energy into electricity. More par shown and described are by way of example and for purposes of illustrative discussion only and are pres ticularly the present invention relates to solar energy ented in the cause of providing what is believed to be conversion into electrical energy by means of a magne 10 the most useful and readily understood description of tohydrodynamic (MHD) generator.

The use of MHD-generators for the production of the principles and conceptual aspects of the invention. In this regard no attempt is made to show structural electrical energy is known. The production of electric details of the system and its constituents in more detail ity by this technique suffers, however, from the inherent than is necessary for a fundamental understanding of the systems' drawback that costly energy is required for 15 invention, the description taken with the drawings mak accelerating ionized gas or liquid metal through the ing apparent to those skilled applied magnetic field in the system in order to produce forms of the invention may bein embodied the art how the several in practice.

the electrical energy. For example, when substantially pure plasma is used with such generators, the operating BRIEF DESCRIPTION OF THE DRAWING temperatures will be in the order of 3000' C. or more, 20 FIG. 1 is a schematic illustration of a system for pro while when liquid metal is accelerated through the ducing electricity according to the invention; and generator by means of plasma produced from fuel com FIG. 2 is a cross-sectional view of a single MHD bustion, the operating temperatures are about 800° C. to channel and its associated magnets and electrodes.

Thus, in addition to the shortcomings of costly fuel 25 DETAILED DESCRIPTION conversion into electrical power, the drawbacks and Referring to the figures, there is shown a plane multi difficulties of operating with such high temperatures, pipe solar energy absorber 2 having closed loop fluid also exist. carrying conduits 4 and 6 leading to and from an or SUMMARY OF THE INVENTION ganic liquid reservoir 8, and adapted to heat said reser 30 voir to the boiling temperature of said liquid. A suitable

The present invention, therefore, proposes a method organic liquid has been found to by Freon, however and a system wherein electrical power is produced by other organic liquids having similar properties of inert means of MHD-generators operating at relatively low ness and a relatively low boiling point, e.g. a boiling temperature, i.e. at temperatures in the order of 80 C. point lower than 100°C., could also be used. to 200 C. and wherein the energy required for acceler 35 The organic liquid reservoir 8 is fitted with a conduit ating liquid metal through the magnetic field is obtained 10 ending with a converging ejector nozzle 12, which from solar energy. Thus, in contradistinction to the nozzle is positioned at the inlet port of a MHD-genera known electricity generating systems of this kind, it is tor 14. There is also provided a liquid alloy reservoir 16, not necessary to consume fuel for obtaining the required for example, a NaK reservoir, having a feeding conduit mechanical driving power. 18 leading to the inlet port of the generator 14. The In accordance with the present invention there is outlet of the generator communicates with a separator provided a method for converting solar energy into 20 and the liquid alloy, after being separated from or electricity by means of a magnetohydrodynamic ganic vapors, is recycled back into the reservoir 16 via (MHD) generator, comprising the steps of: a liquid pipe 22 and where necessary, by means of a (a) providing an organic liquid reservoir having an 45 pump 24. The separated vapors from separator 20 are ejector nozzle positioned at the inlet port of a passed through a conduit 26 to a condenser 28 and the MHD generator; condensed organic liquid is returned through pipe 30 (b) providing a liquid alloy reservoir in fluid commu and by means of a pump 32 to the reservoir 8 for reuse. nication with said inlet port; and A preferred construction of the D.C. MHD-genera (c) heating said organic liquid to its boiling tempera SO tor is shown in the Figures. It consists of a multiplicity ture by means of solar energy absorbers so as to of parallelly disposed channels 34. Each of the channels form high pressure vapors of the organic liquid is of rectangular, high aspect ratio cross-section having adapted to propel the liquid alloy through said two oppositely disposed walls made of electroconduc MHD-generator whereby solar heat energy is con tive material, thus constituting two electrodes 36 and 38 verted into mechanical energy and said mechanical 55 and the two other walls 40 and 42 are made of an insu energy is converted into electrical energy in said lating material. Output leads 44 and 46 are respectively generator. connected to electrodes 36 and 38. Each of the channels The invention further provides a system for convert 34 are placed in the gap of a permanent magnet 48. ing solar energy into electricity by means of a magneto Considering a channel of a height of 10 cm., an induc hydrodynamic (MHD) generator comprising a MHD tion of a magnetic field of about 2000 Gauss, and a flow generator, an organic liquid reservoir having an ejector velocity in the channel of about 50 m/sec., there may be nozzle positioned at the inlet port of said MHD-genera obtained a potential between the electrodes of about 1 tor, a liquid alloy reservoir in fluid communication with volt. Thus if several of the channels' electrode leads are said inlet port, a solar energy absorber adapted to heat connected series higher voltages could be obtained. said organic liquid to a boiling temperature to form 65 The operation of the system can now be readily un vapors adapted to be emitted from said nozzle and to derstood. Liquid, for example, water, contained in the propel the liquid metal through the MHD-generator, absorber's closed loop conduit is heated up by solar wherein solar energy is converted into mechanical en energy and circulated in conduits 4 and 6 to heat up the

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organic liquid in reservoir 8 to its boiling temperature, (d) directing the organic liquid vapors through said (which is about 80° C. for Freon). The organic vapors liquid alloy so as to form a two-phase mixture of a thus formed are passed through conduit 10 and ejected discontinuous vapor phase and a continuous liquid from the nozzle 12 with a velocity between 50 to 100 alloy phase and to propel said mixture through said m/sec. The ejected jet of vapor accelerates the liquid MHD - generator;

alloy present at the inlet port of the MHD-generator (e) separating the vapors from the two-phase mixture; through the channels of the latter, thus converting heat (f) condensing said vapors into liquid; and into mechanical energy and in turn, said mechanical (g) recycling the organic liquid and the separated energy into electricity. The two phase flow at the outlet 10 alloy liquid to their respective reservoirs, whereby port of the generator is then separated, the vapors are solar heat energy is converted into mechanical condensed and each of the liquids are recycled to their energy and said mechanical energy is conterted respective reservoir for reuse. into electrical energy in said generator. Alternatively, in accordance with another embodi solar 2. The method as claimed in claim 1 wherein said ment, not shown in the figures, the propelled two phase energy absorber is adapted to heat liquid disposed flow of vapors and liquid alloy may be separated prior 15 therein and to effect movement of said heated liquid to passing the liquid allow through the generator. Ac through conduit means to heat said organic liquid. 3. The method as claimed in claim 2 wherein said cordingly, between the ejector nozzle and conduit 18, organic liquid is adapted to boil at a temperature below and the input port of the generator there may be be the boiling installed a mechanical separator, for example, a circular 20 absorber. temperature of the liquid disposed in said forked channel (i.e., a cyclone type separator), the input 4. The method as claimed in claim 3 wherein the of which is coupled to said nozzle and conduit 18. In liquid disposed in said absorber is water and said or such an arrangement, one branch of the circular chan ganic liquid is adapted to boil at a temperature below nelled separator is coupled to the inlet port of the gener the boiling temperature of said water. ator and the second branch to a condenser and, in turn, 25 5. The method as claimed in claim 1 wherein said to the organic liquid reservoir. With this type of an liquid alloy is a liquid NaK alloy.

arrangement, the propelled two phase flow is first sepa 6. A method for converting solar energy into electric rated by virtue of the distinct flow of each of said two ity by means of a magnetohydrodynamic (MHD) gener phases in such a circular separator as is known per-se in ator, comprising the steps of:

the art, and consequently only the propelled liquid alloy 30 (a) providing an organic liquid reservoir having an passes through the generator and thereafter is recycled ejector nozzle adapted to emit organic liquid va to its reservoir, while the propelling organic liquid va pors;

pors do not pass through the generator but are con (b) providing a liquid alloy reservoir in fluid commu densed and the liquid is similarly recycled to its reser nication with said ejector nozzle; voir. 35 (c) providing a solar energy absorber and heating said In another possible modification, the organic liquid organic liquid to its boiling temperature by means reservoir can be heated up to its boiling temperature by of the solar energy absorbed by said absorber so as means of, for example, solar absorbers covering the to form high pressure vapors of the organic liquid; walls of the reservoir or by means of parabolic or spher (d) directing said organic - liquid vapors through said ical mirror solar energy absorbers. When such parabolic liquid alloy to form a jet of two-phase mixture of a absorbers are used, the working temperature of the discontinuous vapor phase and a continuous liquid propelling liquid could be in the order of 160° C. to 180" alloy phase;

C. (e) directing a jet of said mixture into a separator While particular embodiments of the invention have wherein the vapors are separated from the liquid been described and shown with reference to the figures 45 alloy while the propelled liquid metal is directed to it will be evident to those skilled in the art that the pass through said MHD - generator: present invention may be embodied in other specific (f) condensing said vapors into liquid; and forms without departing from the spirit or essential (g) recycling the organic liquid and the separated characteristics thereof. The present embodiments are alloy liquid to their respective reservoirs whereby therefore to be considered in all respects as illustrative 50 solar heat energy is converted into mechanical and not restrictive, the scope of the invention being energy and said mechanical energy is converted indicated by the appended claims rather than by the into electric energy in said generator. foregoing description and all changes which come 7. A system for converting solar energy into electri within the meaning and range of equivalency of the cal energy, comprising claims are therefore intended to be embraced therein. 55 (a) a magnetohydrodynamic generator (14) having I claim: inlet and outlet ports;

1. A method for converting solar energy into electric (b) liquid alloy reservoir means (16) for supplying a ity by means of a magnetohydrodynamic (MHD) gener liquid alloy to said inlet port; ator, comprising the steps of: (c) organic liquid reservoir means (8) for storing a (a) providing an organic liquid reservoir having an quantity of an organic liquid having a boiling tem ejector nozzle positioned at the inlet port of a perature less than that of water; MHD generator; (d) solar energy absorption means (2, 46) responsive (b) providing a liquid alloy reservoir in fluid commu to the energy of the sun for boiling the organic nication with said inlet port; liquid in said organic liquid reservoir to the vapor (c) providing a solar energy absorber and heating said 65 phase;

organic liquid to its boiling temperature by means (e) ejector nozzle means (12) for directing the organic of the solar energy absorbed by said absorber so as liquid, vapors through said liquid alloy to form a jet to form high pressure vapors of the organic liquid; of a two-phase mixture of a discontinuous vapor

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phase and a continuous liquid alloy phase and to 9. The system as claimed in claim 7, wherein said propel said liquid alloy through the magnetohydro MHD-generator includes a plurality of parallelly dis dynamic generator; posed electricity producing liquid carrying channels, (f) separator means for separating the vapors from the 5 10.channels said

The being electrically connected in series.

system as claimed in claim 7, wherein perma two-phase mixture; nent magnets are utilized in said MHD-generator for (g) condensing means for condensing said vapors into applying the necessary magnetic field to the liquid al liquid; and loy-carrying-channels thereof.

(h) recycling means for returning the organic liquid 11. The system as claimed in claim 7, wherein the and the alloy liquid to their respective reservoirs, 10 separator means is positioned between the liquid alloy whereby solar energy is converted into mechanical reservoir, wherein the MHD generator and said mixture energy, and mechanical energy is converted into is propelled through said separator, and further wherein electrical energy. the liquid alloy is separated from the propelling vapors 8. The system as claimed in claim 7, wherein said during its propelled flow and substantially only said solar energy absorber is adapted to heat liquid disposed 15 liquid alloy is directed to said magnetohydrodynamic therein and to effect movement of said heated liquid generator. it k is through conduit means to heat said organic liquid.