A system and method for conversion of low-grade thermal energy into electrical energy

Abstract

The present invention provides a system / device and method thereof which uses electrical and magnetic fields for conversion of energy from one form to another and more particularly to a system and method thereof, for conversion of low-grade thermal energy into electrical energy independently or in connection with a multiple such units. The system / device and method thereof of the present invention comprising of a MHD cell comprising an epoxy casing, a first ring type permanent magnet and a second ring type permanent magnet, a liquid entry side planar substrate, a liquid exit side planar substrate, a liquid entry pathway and a liquid exit pathway and a plurality of separators.

Description

A SYSTEM AND METHOD FOR CONVERSION OF LOW-GRADETHERMAL ENERGY INTO ELECTRICAL ENERGYFIELD OF THE INVENTION

[0001] The present invention generally relates to a conversion of energy from one form to another and more particularly to a system and method thereof, for conversion of low-grade thermal energy into electrical energy.BACKGROUND OF THE INVENTION

[0002] With the increasing concerns on the energy shortage and carbon emission issues worldwide, energy recovery from thermal processes is consistently attracting extensive attention. Nowadays, a significant amount of usable thermal energy is wasted and not recovered worldwide every year. Meanwhile, discharging the wasted thermal energy often causes environmental hazards. Significant social and ecological impacts will be achieved if waste thermal energy can be effectively harnessed and reused. The energy recovery from thermal processes, contributing to achieving energy security, environmental sustainability, and a low-carbon future.

[0003] Massive quantities of heat from sources like cooling towers is lost to atmosphere contributing to global warming. In a coal-fired thermal power plant, coal is burnt to produce heat. This heat is used to convert water into steam. The steam drives a turbine connected to a generator, producing electricity. After driving the turbine, the steam needs to be condensed back into water for reuse. Cooling towers facilitate this by removing heat from the water using the cooling effect of water evaporation as shown in Fig-1. About 40% to 60% of the heat produced by burning the coal is radiated in atmosphere through cooling tower.

[0004] Considering the present power generation capacity of 446 Giga Watt in India alone, an estimated 300 Giga Watt of power in the form of heat is continuously radiated in the atmosphere by coal-fired power plants. The generatedelectricity is further put to use which further contributes to heat radiation to atmosphere. For example, cooling towers used for air conditioning plants of a large shopping malls, dissipates several megawatts of heat. Though the magnitude of the heat dissipated is high, the temperatures at which this happens are low i.e. of the order of 60°C.

[0005] Similarly, several chemical processes are exothermic. The reactors in which these processes take place require cooling with jackets or cooling coils through which cooling water is circulated. Heat absorbed by the cooling water is dissipated in cooling towers as shown in figure 2.

[0006] There are several methods to convert heat to electricity. Almost all the methods presently available are not suitable for operation at low temperatures of below 60°C either because of basic feasibility or due to very low conversion efficiency making them economically not viable.

[0007] One of the Techniques presently available is converting water into steam in a boiler. The steam thus produced is used to drive a turbine connected to an alternator and generate electrical energy. However, this technique essentially requires high temperature, hence is not suitable.

[0008] In another technique presently available, thermo-Electric Generator based on Seebeck Effect is used. Two dissimilar metals or differently doped semiconductors are connected in a loop. One end of the loop (‘hot junction’) is held at high temperature, whereas the other end of the loop (‘cold junction’) is held at a lower temperature. This arrangement results in flow of electric current passing through the loop. However, this technique has very low conversion efficiency.

[0009] Another technique presently available is ‘Magneto Hydro Dynamics (MHD)’ based converters. Thermal energy is converted into electrical energy by ionizing gas at very high temperatures and pass through strong magnetic field. Electrodes are placed in the path of ionized gas, to produce Electromotive Force (EMF) therein. Alternatively, molten metals can be used instead of ionized gas. This technique is based on Faraday’s Laws of Electromagnetic Induction. However,GVM-1 this essentially requires high temperature, hence not suitable. Several variants of this technique are available. One such technique is stated in US Patent No. 4,523,113. Here again, the limitations are related to operation at high pressure and temperature around 200°C.

[0010] US 20170213611A1 discloses a method and system for high efficiency electricity generation using low energy thermal heat generation and thermionic devices. The system and method are provided for generating electric power from relatively low temperature energy sources at efficiency levels not previously available. The present system and method employ recent advances in low energy nuclear reaction technology and thermionic / thermotunneling device technology first to generate heat and then to convert a substantial portion of the heat generated to usable electrical power. Heat may be generated by a UENR system employing nuclear reactions that occur in readily available materials at ambient temperatures without a high energy input requirement and do not produce radioactive by products. The heat generated by the UENR system may be transferred through one or more thermionic converter devices in heat transfer relationship with the LENR system to generate electric power.

[0011] US 20060213502A1 discloses a utility scale method and apparatus to convert low temperature thermal energy to electricity. The methods and systems are disclosed to convert low temperature thermal energy to electricity. An example apparatus disclosed herein includes an electrical generating unit to receive heat energy to produce electricity, a concentrator including a heat engine, a liquid piston operatively coupled to the heat engine, and a heat pump operatively coupled to the liquid piston, the heat engine adapted to collect thermal energy, and the heat pump operatively coupled to the electrical generating unit to provide heat to the electrical generating unit. The example apparatus disclosed herein also includes a heat engine floating piston disposed in the heat engine, a heat pump floating piston disposed in the heat pump, and wherein the heat engine floating piston and the heat pump floating piston oscillate.GVM-1

[0012] US 20040251690A1 an application of low-temperature and solid-state pyroelectric energy converter. An application of low-temperature and solid-state pyroelectric energy converter for converting heat produced from low-temperature operations into electric energy, which utilizes man-made waste heat or waste heat from natural environments for producing changes in materials of specific lattice structures, so as to result potential difference caused anisotropy displacement of centers of positive charges and negative charges along directions of polar axes of the lattices, thereby converting heat energy into electric energy. The application is entirely implemented in an environment having a heat source, and thermal energy is continuously converted into electric energy. Therefore, in order to accomplish energy recycling and energy assisting purposes, the application can be extensively applied in appliances or equipment that produce waste thermal energy. In addition, the application can be expanded with respect to size and range to further replace assistant generator applications such as conventional mechanical / electrical generator.

[0013] US 7748219B2 discloses a method and apparatus to convert low temperature thermal energy to electricity. The methods and systems are disclosed to convert low temperature thermal energy to electricity. An example apparatus disclosed herein includes an electrical generating unit to receive heat energy to produce electricity, a concentrator including a heat engine, a liquid piston operatively coupled to the heat engine, and a heat pump operatively coupled to the liquid piston, the heat engine adapted to collect thermal energy, and the heat pump operatively coupled to the electrical generating unit to provide heat to the electrical generating unit. The example apparatus disclosed herein also includes a heat engine floating piston disposed in the heat engine, a heat pump floating piston disposed in the heat pump, and wherein the heat engine floating piston and the heat pump floating piston oscillate.

[0014] Design of MHD Cells have evolved over the years. Figure 3 illustrates a plurality of designs of MHD cells. The most primitive one is known as Segmented Faraday Generator. This is based on Faraday’s Uaw of Induction. EMF is inducedGVM-1 across ionic flow in a magnetic field. Direction of EMF, Magnetic Field and ionic flow are perpendicular to each other. Electrodes are suitably placed to collect the EMF thus produced. This design has a major flaw that when an external load is connected to the electrodes, electric current flows through the ionic flow. Direction of the electric current flow and ionic flow are perpendicular to each other. The electric current thus flowing through the electrodes produces its own magnetic field and produces EMF at a direction different than perpendicular to ionic flow. This phenomenon is known as Hall effect. This impacts efficiency of MHD cells. Subsequent deigns accounted for theses phenomenon resulting in what is known as ‘Disk Generator’. This design overcomes conflicting issues arising from Faraday’s induction and Hall effect and results in better efficiency of the MHD Cell. It may be noted that designs of this prior art are intended to use either ionized gas at high temperatures or molten metals and not suitable for operation at temperatures below 60°C.

[0015] Despite the known solutions, there is still a need to provide an improved method and a simplified system for recovery and utilization of waste heat for power generation enabling use of low-cost equipment and where maximum use of energy and easy control is provided.

[0016] For the reasons stated above, which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for a system and method thereof for conversion of low-grade thermal energy into electrical energy that is useable, scalable and independent of new technology platforms, uses minimum resources that is easy and cost effectively maintained and is portable and can be deployed anywhere in very little time.SUMMARY OF THE INVENTION

[0017] The present invention generally relates to a conversion of energy from one form to another and more particularly to a system and method thereof, for conversion of low-grade thermal energy into electrical energy.GVM-1

[0018] The system of the present invention comprises an epoxy casing, a first ring type permanent magnet and a second ring type permanent magnet, a liquid entry side planar substrate having at least two gold plated copper tracks and a hole at the centre for the passage of the liquid, a liquid exit side planar substrate having at least two gold plated copper tracks, the liquid exit side planar substrate having size smaller than the liquid entry side planar substrate, a liquid entry pathway and a liquid exit pathway and a plurality of separators. The epoxy casing at its inner top surface envelops the first ring type permanent magnet. The south pole of the first ring type permanent magnet placed flush to the inner top surface of the epoxy casing. The liquid entry side planar substrate is placed flush to the north pole of the first ring type permanent magnet with the gold plated copper tracks of the liquid entry side planar substrate facing other side of the north pole of the first ring type permanent magnet. The liquid exit side planar substrate is placed below the liquid entry side planar substrate with the gold plated copper tracks of the liquid exit side planar substrate facing to the gold plated copper tracks of the liquid entry side planar substrate. The liquid entry side planar substrate and the liquid exit side planar substrate are separated by adopting a plurality of separators. The second ring type permanent magnet is placed flush to the liquid exit side planar substrate with its south pole touching to the other surface of liquid exit side planar substrate than the surface having the gold plated copper tracks. A liquid passage pathway is maintained between the north pole surface of the second ring type permanent magnet and the inner bottom surface of the epoxy casing. The liquid entry pathway is provided at the top side of the epoxy casing and the liquid exit pathway is provided at the bottom side of the epoxy casing.

[0019] The method of present invention for conversion of low-grade thermal energy into electrical energy is comprising step of transferring, by using heat exchanger and circulation pump heat from condenser to the ionic liquid. The method includes step of circulating, by a circulation pump an ionic liquid through the system for conversion of low-grade thermal energy into electrical energy through an upper nipple. The method includes step of passing, the ionic liquidGVM-1 through the upper nipple (10) connected to the center of liquid entry side planar substrate. The method includes step of passing the ionic liquid over inner electrodes of a liquid entry side planar substrate and a liquid exit side planar substrate and then passing over outer electrodes of the liquid entry side planar substrate and the liquid exit side planar substrate. The method includes step of flowing the ionic liquid over liquid exit side planar substrate. The method includes step of exiting the ionic liquid from the system through bottom nipple (20). The method further includes step of collecting, across inner and outer electrodes an EMF generated and connecting to an external electrical load.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The embodiments can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, the emphasis instead being placed upon illustrating the principles of the embodiments. Moreover, the figures, like reference numerals designate corresponding parts throughout the different views.

[0021] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

[0022] The above and other objects, features, and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:Figure 1 illustrates a cooling tower system at a coal-fired thermal power plant.Figure 2 illustrates a cooling tower system at a chemical reactor plant.Figure 3 illustrates a plurality of designs of MHD cells.GVM-1Figure 4 illustrates construction of MHD cell of the system / device and method thereof according to one of the embodiment of the present invention.Figure 5 illustrates two circular Printed Circuit Boards (planar substrates) to be placed in between the magnets of the system / device and method thereof according to one of the embodiments of the present invention.Figure 6 illustrates the ionic liquid flow cutting through the magnetic field of the ring magnets of the MHD cell of the system / device and method thereof according to one of the embodiment of the present invention.Figure 7 illustrates one of the practical implementations of the system / device and method thereof of the present invention.Figure 8 illustrates an implementation of MHD cells to have better conversion of heat to electricity and increase the voltage generation according to one of the embodiments of the system / device and method thereof of the present invention.Figure 9 illustrates construction of a typical diaphragm pump according to one of the embodiments of the system / device and method thereof of the present invention.Figure 10 illustrates construction of the MHD cell with reduced reluctance of magnetic flux path according to one of the embodiments of the system / device and method thereof of the present invention.Figure 11 illustrates permanent magnet used to establish proof of concept of the system according to one of the embodiment of the present invention.Figure 12 illustrates the dimensions of the liquid entry side planar substrate and liquid exit side planar substrate used to establish proof of concept of the system according to one of the embodiments of the present invention.Figure 13 illustrates a nipple used to establish proof of concept of the system according to one of the embodiment of the present invention.Figure 14 illustrates pictures of assembled system constituting MHD cell from different angles according to one of the embodiment of the present invention.GVM-1Figure 15 Mini Diaphragm Pump utilize to establish proof of concept of the system according to one of the embodiment of the present invention.Figure 16 illustrates the flow of the Ionic Liquid through the system according to one of the embodiment of the present invention.Figure 17 illustrates proportional thickness of the slice of the current path at inner electrodes to outer electrodes at the established proof of concept of the system according to one of the embodiment of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention is a system / device and method thereof which uses electrical and magnetic fields for conversion of energy from one form to another and more particularly to a system and method thereof, for conversion of low-grade thermal energy into electrical energy independently or in connection with a multiple such units.

[0024] In the following description, for the purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.

[0025] The various embodiments of the present invention provide a system / device and method thereof that assists in conversion of energy from one form to another and more particularly for conversion of low-grade thermal energy into electrical energy independently or in connection with a multiple such units.

[0026] Furthermore, connections between components and / or modules within the figures are not intended to be limited to direct connections. Rather, these components and modules may be modified, re-formatted or otherwise changed by intermediary components and modules.GVM-1

[0027] The systems / device and methods described herein are explained using examples with specific details for better understanding. However, the disclosed embodiments can be worked on by a person skilled in the art without the use of these specific details.

[0028] Throughout this application, with respect to all reasonable derivatives of such terms, and unless otherwise specified (and / or unless the particular context clearly dictates otherwise), each usage of:“a” or “an” is meant to read as “at least one.”“the” is meant to be read as “the at least one.”References in the present invention to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

[0029] Embodiments of the present invention include various steps, which will be described below. The steps may be performed by mechanical, magnetic, electrical components or may be embodied in a mechatronic system, machine-executable instructions, which may be used to cause a general-purpose or special purpose processor programmed with the instructions to perform the steps. Alternatively, steps may be performed by a combination of mechanical, magnetic, electrical components and / or by human operators.

[0030] If the specification states a component or feature "may1can", "could", or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

[0031] As used in the description herein and throughout the claims that follow, the meaning of "a, an," and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise.GVM-1

[0032] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this invention will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure).

[0033] Hereinafter, embodiments will be described in detail. For clarity of the description, known constructions and functions will be omitted. Parts of the description may be presented in terms of operations performed by a Mechanical / Magnetic / Electrical / Electronic system.

[0034] While embodiments of the present invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the invention, as described in the claim.

[0035] In one of the embodiment of the present invention the system / device and method thereof converts energy from one form to another and more particularly converts low-grade thermal energy into electrical energy. The object of the system and method thereof of the present invention is to convert thermal energy of low temperature sources, such as cooling towers, heat exchangers, solar panels to electrical energy with high efficiency. The system and method thereof of the present invention is aimed at converting heat lost to atmosphere at low temperatures, yet high volumes through equipment such as exothermic systems including but not limited to cooling towers.GVM-1

[0036] The present invention the system / device and method thereof of the present invention is based on the principles of Magneto Hydro Dynamic (MHD) power generators. The basic principle is an EMF is generated when ionic movement takes place in a magnetic field. Direction of movement of ionic fluid, Magnetic Flux and EMF generated are perpendicular to each other. Conventional MHD Generators are based on movement of ionized gases or liquid metals. Ionization essentially happens at high temperatures. Metals with melting point well below 60°C are available, such as Mercury -38.83 °C, Cesium 28.44 °C, Francium 27 °C, Gallium 29.76 °C. However, these metals are either hazardous or highly reactive or very expensive.

[0037] In an implementation according to one of the embodiments of the present invention the system / device and method thereof use ionic liquids. An ionic liquid (IL) is a salt in the liquid state at ambient conditions. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as 100 °C. While ordinary liquids such as water and gasoline are predominantly made of electrically neutral molecules, ionic liquids are largely made of ions.

[0038] In an implementation according to one of the embodiments of the system / device and method thereof of the present invention the ionic liquid absorbs heat energy after which it passes through strong magnetic field, because of which electromotive force (EMF) is generated. Generation of EMF results in generation of electrical power whereby heat energy is converted into electrical energy. The operation happens in a closed cycle.

[0039] Figure 4 illustrates construction of MHD cell of the system / device and method thereof according to one of the embodiment of the present invention. According to one of the embodiment of the present invention the system of the present invention is a MHD cell. The system of the present invention comprises an epoxy casing, a first ring type permanent magnet and a second ring type permanent magnet, a liquid entry side planar substrate having at least two gold plated copper tracks and a hole at the centre for the passage of the liquid, a liquid exit side planarGVM-1 substrate having at least two gold plated copper tracks, the liquid exit side planar substrate having size smaller than the liquid entry side planar substrate, a liquid entry pathway and a liquid exit pathway and a plurality of separators. The epoxy casing at its inner top surface envelops the first ring type permanent magnet. The south pole of the first ring type permanent magnet placed flush to the inner top surface of the epoxy casing. The liquid entry side planar substrate is placed flush to the north pole of the first ring type permanent magnet with the gold plated copper tracks of the liquid entry side planar substrate facing other side of the north pole of the first ring type permanent magnet. The liquid exit side planar substrate is placed below the liquid entry side planar substrate with the gold plated copper tracks of the liquid exit side planar substrate facing to the gold plated copper tracks of the liquid entry side planar substrate. The liquid entry side planar substrate and the liquid exit side planar substrate are separated by adopting a plurality of separators. The second ring type permanent magnet is placed flush to the liquid exit side planar substrate with its south pole touching to the other surface of liquid exit side planar substrate than the surface having the gold plated copper tracks. A liquid passage pathway is maintained between the north pole surface of the second ring type permanent magnet and the inner bottom surface of the epoxy casing. The liquid entry pathway is provided at the top side of the epoxy casing and the liquid exit pathway is provided at the bottom side of the epoxy casing.

[0040] Figure 5 illustrates two circular Printed Circuit Boards (planar substrates) to be placed in between the magnets of the system / device and method thereof according to one of the embodiments of the present invention. In an implementation according to one of the embodiments of the system / device and method thereof of the present invention two ring-type magnets with a hole in the center are used. Two circular Printed Circuit Boards (planar substrates) as shown in Fig-4 are placed in between the magnets. Small separators (not shown in the drawings) are placed in between the planar substrates. The circular planar substrates have gold-plated copper tracks shown as ‘ Outer Electrode ’ and ‘ Inner Electrode ’ . The Diameters and thickness of these tracks are identical (respectively) on both the planar substrates.GVM-1 planar substrate shown as ‘Liquid Entry Side planar substrate’ has a hole in the center. Overall diameter of the liquid entry side planar substrate is larger than planar substrate shown as ‘Liquid Exit Side planar substrate’.

[0041] Figure 6 illustrates the ionic liquid flow cutting through the magnetic field of the ring magnets of the MHD cell of the system / device and method thereof according to one of the embodiment of the present invention. In an implementation according to one of the embodiments of the system / device and method thereof of the present invention ionic liquid passes through a small pipe connected to the centre of liquid entry side planar substrate. Ionic liquid then passes over inner electrodes of both the planar substrates then over outer electrodes of both the planar substrates, then flows over liquid exit side planar substrate before exiting from the MHD cell. During the passage through the two planar substrates, the ionic liquid cuts through the magnetic field of the ring magnets. Since movement of ionic liquid is in perpendicular direction to magnetic field, an EMF is generated across the liquid as a vector resultant of Faraday and Hall effects . This EMF is collected across inner and outer electrodes and in-tum connected to external electrical load.

[0042] Figure 7 illustrates one of the practical implementations of the system / device and method thereof of the present invention. In an implementation according to one of the embodiments of the system / device and method thereof of present invention the cooling tower in the prior art system shown in the figure 1 has been replaced by MHD Cell of present invention. As illustrated in the figure 7 a Heat Exchanger and circulation pump is used to transfer the heat of water from condenser to ionic liquid. Ionic liquid absorbs heat of water and passes through MHD Cell, where it releases electrical energy and in-tum loses thermal energy. As a result, temperature of ionic liquid drops down. Cold ionic liquid passes through heat exchanger where it again absorbs heat of hot water. A circulation pump is provided for circulation of ionic liquid through heat exchanger. Similarly, cooling towers used in other applications like cooling of chemical reactors, air-conditioning plants can be replaced with MHD cells to produce electrical power from the heat which otherwise would have been lost to atmosphere.GVM-1

[0043] Figure 8 illustrates an implementation of MHD cells to have better conversion of heat to electricity and increase the voltage generation according to one of the embodiments of the system / device and method thereof of the present invention. Generally Voltages generated in such MHD cells are low. In an implementation according to one of the embodiments of the present invention it is possible to connect several such cells in series to increase the voltage as well as have better conversion of heat to electricity as illustrated in figure 8. Advantage of this design of MHD cell is that potential of ionic liquid entering the cell is same as that of the inner electrode and potential of ionic liquid exiting the cell is same as that of the outer electrode. This allows easy connection of multiple MHD cells in series. This may result in possibility of electrical short-circuit through the path of ionic liquid outside the MHD cell through the circulating pump, heat-exchanger. However to neutralize the possibility of such electrical short-circuit the circulation pump having electrical isolation between suction and discharge are used.

[0044] Figure 9 illustrates construction of a typical diaphragm pump according to one of the embodiments of the system / device and method thereof of the present invention. In an implementation according to one of the embodiments of the present invention circulation pump used for ionic liquid is of the type which provides electrical isolation between suction and discharge. Diaphragm type pumps with non-metallic construction as illustrated in figure 9 are suitable for this application.

[0045] Figure 10 illustrates construction of the MHD cell with reduced reluctance of magnetic flux path according to one of the embodiments of the system / device and method thereof of the present invention. EMF produced is proportional to magnetic flux density and velocity of the ionic liquid. Magnetic flux density depends upon strength of magnets, reduction in reluctance of magnetic flux path. Rare earth magnets, such as Neodymium magnets are suitable for this application. Reluctance of magnetic flux path can be reduced by reducing the distance between poles of magnets i.e. by reducing the gap between the two planar substrates, use of thinner planar substrates such as ceramic substrates. Reluctance of magnetic flux path can be further reduced by providing a magnetic material between oppositeGVM-1 faces of the ring magnets. Reduction in gap between two planar substrates results in increase in velocity and thereby increase in generated EMF. This also results in reduction of internal resistance of MHD cell thereby improving conversion efficiency.

[0046] In an exemplary embodiment the proof of concept of the system is established by fabricating and assembling various components in accordance with the system of the present invention. As illustrated in the figure 11 the two permanent magnets are used having dimensions as outer diameter 90mm, inner diameter 36mm and thickness 15mm. Each of the two permanent magnets used have Magnetic Flux(B) equal to 0. 15 T in the present assembled system. The figure 12 depicts the dimensions of the liquid entry side planar substrate and liquid exit side planar substrate used for the proof of concept of the system. The liquid entry side planar substrate and liquid exit side planar substrate are exemplarily made up of Glass- reinforced epoxy laminate FR4 material. The liquid entry side planar substrate has diameter of 118 mm with a hole for liquid entry of diameter of 12 mm at the centre of said planar substrate. The gold-plated copper track acting as Outer Electrode on each of the liquid entry side planar substrate and liquid exit side planar substrate have inner diameter as 94mm with a track width of 6mm and track thickness of 0.4mm. The gold-plated copper track acting as Inner Electrode on each of the liquid entry side planar substrate and liquid exit side planar substrate have outer diameter as 56mm with a track width of 6mm. Each of the liquid entry side planar substrate and liquid exit side planar substrate are made of Glass-reinforced epoxy laminate FR4. The nipple illustrated in figure 13 have been attached to the liquid entry side planar substrate and another nipple have been attached to the hole at the bottom surface of the epoxy casing. The ionic liquid used for proof of concept have properties including boiling point 198°C, melting point -2°C, density 1.04 (20°C), Flash point 92°C, storage temperature ambient and electrical conductivity 1.0 mS / cm. The proof of concept of the system utilizes Mini Diaphragm Pump as illustrated in figure 15. The Liquid Entry Side planar substrate and Liquid Exit Side planar substrates were separated by small insulating pieces of 0.1 mm thickness.GVM-1The Connecting wires were soldered to inner and outer electrodes. The Ring magnets are placed on both planar substrates. A nipple was glued above the 12 mm diahole of Entry Side planar substrate. An enclosure made up of acrylic was formed and the assembly of magnets and planar substrates was placed in it. A nipple was attached to the bottom of assembly. The arrangement is such that the ionic liquid enters the Entry Side planar substrate through the nipple attached to it, passes over the inner and outer electrodes, then passes over Liquid Exit Side planar substrate, which is smaller in diameter than Liquid Entry Side planar substrate, gets collected over the bottom of the cell and comes out of the nipple at the bottom of the cell. The complete assembly is sealed with epoxy to prevent leakages. Two tiny temperature sensors of type PT 100 were placed close to the nipples on entry and exit side. Flexible tubing was connected to form a close loop of measuring flask - diaphragm pump - inlet of MHD cell - outlet of MHD cell - measuring flask. A measuring flask was fdled with Ionic Liquid 1 -Methylimidazole. Power supply was connected to the pump. The Voltage developed across the inner and outer electrodes was measured. Also short-circuit current was measured. The Magnetic Flux (B) was measured with Flux Meter. Flow rate of pump was measured by keeping the loop open. Change in volume of Ionic Liquid in a given time was measured to calculate flow rate. The Comparison of theoretical estimation and practical measurements of performance is performed to establish the successful construction and execution of the system and method thereof of the present invention.

[0047] According to one of the embodiments of the present invention the several variables required to be considered for a practical design of the system of the present invention includes but not limited to materials, field strength and geometry of magnets, substrate material, gap between the substrates, selection of ionic liquid.Basic equation for emf generated in MHD Cell is:Emf (Volts) = B X L X V, Where B= Magnetic Flux Density in TeslaL= Length of passage of ionic liquid perpendicular to the magnetic flux in meterGVM-1V= Velocity of ionic liquid in meter per secondStronger magnets produce higher emf for a smaller passage of ionic liquid. Magnets made up of materials like Neodymium compounds (NdFeB) can provide flux density as high as 1 Tesla. The exemplarily proposed design employs a ring magnet. Geometry of the magnet has bearing on overall design of the system of the present invention constituting a MHD Cell.

[0048] According to one of the embodiments of the present invention the Substrate material should have high electrical resistivity, mechanical strength to withstand operating pressure and temperature conditions, smooth surface finish for less resistance to flow of ionic liquid. Substrate should be as thin as possible to minimize reluctance to magnetic flux. Ceramics, Glass Epoxy are some of the suggested materials. Conductive tracks are required to be plated on the substrate.

[0049] According to one of the embodiments of the present invention the Velocity of laminar flow of ionic liquid passing through the magnetic field is a function of inlet pressure and gap between substrates. Smaller gaps results in higher velocity for a given inlet pressure . However smaller gap results in higher electrical resistance of ionic liquid between the electrodes. Higher electrical resistance implies lesser power available from the cell. Smaller gap also results in higher pressure drop of flow of ionic liquid across the cell.

[0050] According to one of the embodiments of the present invention the characteristics required to be considered for selection of ionic liquids includes but not limited to electrical conductivity, electrochemical window, operating temperature range and specific heat. Higher electrical conductivity results in better efficiency due to lesser losses inside the cell. Specific conductive additives enhance electrical conductivity of Ionic Liquids. The electrochemical window is the range of potentials over which the ionic liquid remains stable without undergoing decomposition. This determines the maximum voltage that is allowed to be produced across each MHD Cell. The Ionic Liquid should remain stable in theGVM-1 operating temperature range. Further, higher the specific heat, lesser flow rates are required through the MHD Cells to absorb the required heat.

[0051] In an embodiment staging the exemplary implementation of the present invention the permanent magnets considered capable of producing magnetic flux density of 0.15 T and dimensions as shown in figure 11. The substrate considered for the liquid entry side planar substrate and liquid exit side planar substrate is PCB with gold plated copper tracks as shown in figure 12. The gap considered between the two substrates, the liquid entry side planar substrate and liquid exit side planar substrate is gap of 0.5 mm. Preferably pieces of Teflon with thickness of 0.5 mm are considered as separators between the two substrates. The ionic liquid considered is 1-Methylimidazole having following properties:Boiling Pt: 198 °CMelting Pt: -2 °CDensity: 1.04 (20 °C)Flash Pt: 92 °CStorage Temperature: Ambient Electrical conductivity: l.O mS / cm.

[0052] The figure 16 illustrates the flow of the Ionic Liquid through the system according to one of the embodiments of the present invention. The Ionic Liquid passes from Inner Electrodes to Outer Electrodes under Magnetic Flux Density ‘B’ . This magnetic field is perpendicular to the direction of flow of Ionic Liquid. Ionic Liquid flows with a velocity ‘V’. As a result, Emf ‘E’ is produced in a direction perpendicular to direction of flow of Ionic Liquid as well as perpendicular to Magnetic Field as per laws of motional emf derived from Farady’s law. This Emf ‘E’ is generated across the length ‘L’ as shown in the above figure. Emf is given by equation:E = B x L x V (Equation 1)Where, E is in Volts, B in Tesla, L in meters, V in meter per second. In the POC setup, ‘B’ was measured with Flux meter as 0. 15 TeslaGVM-1L as derived from the geometry of PCBs is 37.75 mm = 0.03775 meterVelocity is derived in the following manner:The PCBs are separated by an insulator of thickness ‘d’ = 0.1 mm Flow rate of the pump was measured as 4 liter per min = 0.004 m3 / min =6.66 x 10‘5m3 / secCross section of total area through which Ionic Liquid flows is = circumference of inner electrode x thickness of insulation = 56 x pi x 0.1 = 17.595 mm2= 17.595 x 10‘6meter2Therefor velocity:of Ionic Liquid at Inner Electrode = — 17.659656Xx 1100 (5—6)m / Sec= 3.788 m / secSubstituting the above values in Equation 1 gives,E = 0.15 x 0.03775 x 3.788 = 21.45 x 10’3Volts i.e. 21.45 millivoltsDuring actual experiment 17.945 millivolts were observed.The error can be attributed to estimation of measurement of magnetic flux density ‘B’ as well as flow rate of Pump.

[0053] To estimate the maximum power that can be delivered by the MHD cell, it is important to calculate the internal resistance of the cell. As per maximum power theorem, maximum power is delivered when the source resistance equals load resistance. Internal resistance of the MHD Cell is estimated in the following manner:

[0054] The current flows from the pair of inner electrodes to pair of outer electrodes. Consider a small slice of this path with thickness of 0.1 mm at inner electrodes as illustrated in figure 17. Thickness of the slice works out to be 0.168 mm on outer electrodes; proportional to the diameters of the electrodes. The Figure 17 illustrates proportional thickness of the slice of the current path at inner electrodes to outer electrodes.Resistance of this slice =p * L / A Where,GVM-1 p is resistivity of the Ionic Liquid. Conductivity of 1 -Methylimidazole is 10 mS / cm i.e. Resistivity is 1 ohm-mL= Length of the slice, which is 19 mmA= Average cross-sectional area of the slice = (0.1+0.186) / 2 * 0.1 mm2= 0.013392857 mm2Resistance of 1 slice therefore works out to be 1418666 ohms.A total of 56 x 3.142 / 0. 1 = 1759 slices are in parallel.Effective resistance of the cell therefore works out to be 1418666 / 1759 = 806 ohms.Expected short circuit current is 17.945 mV / 806 ohms = 0.022 mA= 22 micro Amp, which matches with observed results.The maximum power therefore becomes approximately 0.1 microwatt.

[0055] In an implementation according to one of the embodiments of the present invention the permanent magnets considered are Neodymium Ring Magnets capable of producing magnetic flux density of 1 T and dimensions as shown in figure 11. The substrate considered for the liquid entry side planar substrate and liquid exit side planar substrate is Glass Epoxy PCB of FR4 with gold plated copper tracks as shown in figure 12. The gap considered between the two substrates, the liquid entry side planar substrate and liquid exit side planar substrate is gap of 0.5 mm. Preferably pieces of Teflon with thickness of 0.5 mm are considered as separators between the two substrates. The ionic liquid considered is l-Butyl-3- methylimidazolium (BMIM) with Lithium Salts LiBF4 or LiPF6. The ionic liquid considered l-Butyl-3-methylimidazolium (BMIM) with Lithium Salts LiBF4 or LiPF6 have following properties:Electrical Conductivity: ~ 200 S / m i.e. Resistivity of 0.005 ohm-meter, Electrochemical Window: ~ 4 Volts, Specific Heat: 1.26 J / g.K,Operating Temperature Range: -70°C to +192 °C.GVM-1

[0056] The figure 16 illustrates the flow of the Ionic Liquid through the system according to one of the embodiments of the present invention. The Ionic Liquid passes from Inner Electrodes to Outer Electrodes under Magnetic Flux Density ‘B’ . This magnetic field is perpendicular to the direction of flow of Ionic Liquid. Ionic Liquid flows with a velocity ‘V’. As a result, Emf ‘E’ is produced in a direction perpendicular to direction of flow of Ionic Liquid as well as perpendicular to Magnetic Field as per laws of motional emf derived from Farady’s law. This Emf ‘E’ is generated across the length ‘L’ as shown in the above figure. Emf is given by equation:E = B x L x V (Equation-1)Where, E is in Volts, B in Tesla, L in meters, V in meter per second.B=1 Tesla for the magnets selectedL= L as derived from the geometry of planar substrates is 37.75 mm = 0.03775 meterDesign EMF should be less than Electrochemical Window of ionic liquid selected, which is 4 Volts. Design EMF is considered as 3.5 Volts. Substituting these values in Equation- 1 above,V= 92.72 meter per secondRelation between average velocity and flow-rate at inlet of the cell is calculated in the following manner:Distance between inner ring and outer ring of electrodes is 47-28 = 19 mm1.e. mid-point is at 28 + 19 / 2 mm = 37.5 mm from center ofplanar substrate. Circumference at mid-point is 2 II r = 2 X 3.142 X 37.5= 235.65 mm Separation between two planar substrates is 0.5 mm.Cross-section at circumference at mid-point is =235.65 X 0.5 = 117.825 mm2= 117.825 X W6meter2Flow rate (m3 / sec) = Cross Section Area (m2) X Velocity (m / sec) (Equation-2)Substituting the required cross-section and velocity and in above Equation-2,GVM-1Flow rate = 117.825 X IO’6X 92.72 = 0.01092 m3 / sec = 655.45 liter per min.The error can be attributed to estimation of measurement of magnetic flux density ‘B’ as well as flow rate of Pump.

[0057] To estimate the maximum power that can be delivered by the MHD cell, it is important to calculate the internal resistance of the cell. As per maximum power theorem, maximum power is delivered when the source resistance equals load resistance. Internal resistance of the MHD Cell is estimated in the following manner:

[0058] The current flows from the pair of inner electrodes to pair of outer electrodes. Consider a small slice of this path with thickness of 0.1 mm at inner electrodes as illustrated in figure 17. Thickness / width of the slice works out to be 0. 168 mm on outer electrodes; proportional to the diameters of the electrodes. The Figure 17 illustrates proportional thickness of the slice of the current path at inner electrodes to outer electrodes.Resistance of this slice =p * L / A Equation-3Where, p is resistivity of the Ionic Liquid. Resistivity of selected ionic liquid is 0.005 ohm-meterL= Length of the slice, which is 19 mm = 0.019 meterA= Average cross-sectional area of the slice = (0.1+0. 168) / 2 * 0.5 mm2for spacing of 0.5 mm between two planar substrates = 0.0669 mm2= 0.0669 X 1 O'6meter2Substituting these values in Equation-3Resistance of 1 slice works out to be (0.005 X 0.0190) / 0.0715 X 10‘6Ohm = 1418.6 ohmA total of 56 x 3.142 / 0. 1 = 1759 slices are in parallel.Effective internal resistance of the cell therefore works out to be 1418.6 / 1759=0.8062 ohms.GVM-1As per maximum power theorem, the power that can be delivered = = Voltge2 / Internal Resistance Equation-4For design voltage of 3.5 Volts,Maximum power available = 3.52 / 0.8062 = 15.17 WattIf the MHD Cell thus developed is used to replace Cooling Tower which dissipates say 1 Mega Watt, atotal of 1000000 / 15.17= 65,919 cells would be required. These cells can be connected in a suitable combination of series and parallel circuits.Typical design of a conventional Cooling Tower which dissipates 1 Mega Watt of power requires base area of about 15 m2, Height of about 30 m i.e. occupies volume of about 450m3The power density therefore works out to be 1,000,000 / 450 = 2222.2 Watts / m3If this cooling tower provides Delta T of 10°C, it would require flow rate of water as 1440 liter per min.The MHD Cell thus developed would have dimensions of about 150mm X 150mm X 100mm considering piping connections for inlet and outlet of ionic liquid.The total volume of such cell therefore works out to be 0.15 X 0.15 X 0.1 m3= 0.00225 m3Power density therefore works out to be 15.17 / 0.00225 = 6742.2 Watts / m3

[0059] It can be thus seen that MHD Cell offers higher power density with reduced flow rates of cooling medium as compared to conventional Cooling Tower while recovering energy otherwise lost to atmosphere.GVM-1

[0060] In an implementation according to one of the embodiments of the present invention a system for conversion of low-grade thermal energy into electrical energy is comprising of an epoxy casing having a hole in the centre of a top surface and a hole in the centre of a bottom surface through the thickness of the surfaces. The system is comprising of a first ring type permanent magnate with a hole in the center that is placed interior to the inner top surface of the epoxy casing with its south pole placed flush at the inner top surface of the epoxy casing. The system is comprising of a liquid entry side planar substrate with hole in the centre through the thickness of the liquid entry side planar substrate. The liquid entry side planar substrate is placed below the first ring type permanent magnate with a first surface forming up per surface of the liquid entry side planar substrate placed flush to the north pole of the first ring type permanent magnate. The system is comprising of at least two gold plated copper tracks placed concentrically on a second surface forming lower surface of the liquid entry side planar substrate facing other side of the north pole of the first ring type permanent magnet. The system is comprising of an upper nipple (10) that is housed through the hole in the top surface of epoxy casing and the hole in the liquid entry side planar substrate constituting a liquid entry pathway. The system is comprising of a liquid exit side planar substrate. The liquid exit side planar substrate has size smaller than the liquid entry side planar substrate. The liquid exit side planar substrate is placed spaced apart below the liquid entry side planar substrate. The system is comprising of at least two gold plated copper tracks placed concentrically on a first surface forming upper surface of the liquid exit side planar substrate, at least two gold plated copper tracks placed concentrically on a first surface forming upper surface of the liquid exit side planar substrate face to the at least two gold plated copper tracks placed concentrically on second surface forming lower surface of the liquid entry side planar substrate. The system is comprising of a plurality of separators. The plurality of separators are placed between the second surface forming lower surface of the liquid entry side planar substrate and the first surface forming upper surface of the liquid exit side planar substrate. The plurality of separators holds the liquid entry side planar substrate and the liquid exit side planar substrate spaced apart, maintaining aGVM-1 passage for liquid flow. The system comprises a second ring type permanent magnate with a hole in the center. The second ring type permanent magnate with a hole in the center is placed flush to the liquid exit side planar substrate with its south pole flush to the lower surface of the liquid exit side planar substrate that is the other surface of liquid exit side planar substrate than the surface having the gold plated copper tracks. The system is comprising of a liquid passage pathway. The liquid passage pathway is maintained between the north pole surface of the second ring type permanent magnet and the inner bottom surface of the epoxy casing. The system further comprising of a bottom nipple (20). The bottom nipple (20) is housed through hole in the bottom surface of the epoxy casing constituting a liquid exit pathway.

[0061] In an implementation according to one of the embodiments of the present invention a system for conversion of low-grade thermal energy into electrical energy, the hole in the centre of the top surface of the epoxy casing and the hole in the centre of liquid entry side planar substrate are concentrically aligned to house the upper nipple (10) configuring liquid entry path for the passage of the liquid.

[0062] In an implementation according to one of the embodiments of the present invention a system for conversion of low-grade thermal energy into electrical energy, the outer gold plated copper track of the at least two gold plated copper tracks placed on each of the liquid entry side planar substrate and liquid exit side planar substrate acts as an Outer Electrode. The inner gold plated copper track of the at least two gold plated copper tracks placed on each of the liquid entry side planar substrate and liquid exit side planar substrate acts as an Inner Electrode.

[0063] In an implementation according to one of the embodiments of the present invention a system for conversion of low-grade thermal energy into electrical energy, the Diameters and thickness of the gold-plated copper tracks acting as Outer Electrode and Inner Electrode are identical (respectively) on both the planar substrates, the liquid entry side planar substrate and the liquid exit side planar substrate.GVM-1

[0064] In an implementation according to one of the embodiment of the present invention a system for conversion of low-grade thermal energy into electrical energy, the epoxy casing is preferably cylindrical in shape. Further, the liquid entry side planar substrate and the liquid exit side planar substrate are preferably circular in shape.

[0065] In an implementation according to one of the embodiments of the present invention a system for conversion of low-grade thermal energy into electrical energy, the ionic liquid passes through the upper nipple (10) connected to the center of liquid entry side planar substrate. The ionic liquid further passes over inner electrodes of both the planar substrates and then passes over outer electrodes of both the planar substrates. The ionic liquid further flows over liquid exit side planar substrate before exiting from the system through bottom nipple (20). The ionic liquid thus cut through the magnetic field of the ring magnets through its movement in perpendicular direction to magnetic field and generates an EMF across the liquid. This EMF is collected across inner and outer electrodes and connected to external electrical load. The potential of ionic liquid entering the cell is same as that of the inner electrode and a potential of ionic liquid exiting the cell is same as that of the outer electrode.

[0066] In an implementation according to one of the embodiment of the present invention a system for conversion of low-grade thermal energy into electrical energy, a circulation pump is used for ionic liquid flow circulation is of the type which provides electrical isolation between suction and discharge.

[0067] In an implementation according to one of the embodiments of the present invention a system for conversion of low-grade thermal energy into electrical energy, the reluctance of magnetic flux path is reduced by reducing the distance between poles of magnets i.e. by reducing the gap between the two planar substrates, by use of thinner planar substrates such as ceramic substrates, and by providing a magnetic material between opposite faces of the ring magnets thereby improving conversion efficiency.GVM-1

[0068] In an implementation according to one of the embodiment of the present invention a system for conversion of low-grade thermal energy into electrical energy is configured to constitute a MHD cell.

[0069] In an implementation according to one of the embodiment of the present invention a method for conversion of low-grade thermal energy into electrical energy is comprising step of transferring, by using heat exchanger and circulation pump heat from condenser to the ionic liquid. The method includes step of circulating, by a circulation pump an ionic liquid through the system for for conversion of low-grade thermal energy into electrical energy through an upper nipple. The method includes step of passing, the ionic liquid through the upper nipple (10) connected to the center of liquid entry side planar substrate. The method includes step of passing the ionic liquid over inner electrodes of a liquid entry side planar substrate and a liquid exit side planar substrate and then passing over outer electrodes of the liquid entry side planar substrate and the liquid exit side planar substrate. The method includes step of flowing the ionic liquid over liquid exit side planar substrate. The method includes step of exiting the ionic liquid from the system through bottom nipple (20). The method further includes step of collecting, across inner and outer electrodes an EMF generated and connecting to an external electrical load.

[0070] In an implementation according to one of the embodiments of the present invention a method for conversion of low-grade thermal energy into electrical energy during passing though the two planar substrates ionic liquid cuts through the magnetic field of the ring magnet.

[0071] In an implementation according to one of the embodiment of the present invention a method for conversion of low-grade thermal energy into electrical energy the movement of ionic liquid is in perpendicular direction to the magnetic field.

[0072] In an implementation according to one of the embodiment of the present invention a method for conversion of low-grade thermal energy into electricalGVM-1 energy the EMF produced is proportional to the magnetic flux density and velocity of the ionic liquid.

[0073] In an implementation according to one of the embodiment of the present invention a method for conversion of low-grade thermal energy into electrical energy a potential of ionic liquid entering the cell is same as that of the inner electrode and a potential of ionic liquid exiting the cell is same as that of the outer electrode.

[0074] In an implementation according to one of the embodiment of the present invention a method for conversion of low-grade thermal energy into electrical energy circulation pump used for ionic liquid circulation flow is of the type which provides electrical isolation between suction and discharge.

[0075] In an implementation according to one of the embodiment of the present invention a method for conversion of low-grade thermal energy into electrical energy the method further comprise step of reducing reluctance of magnetic flux path by reducing the distance between poles of magnets by reducing the gap between the two planar substrates, using thinner planar substrates such as ceramic substrates, and by providing a magnetic material between opposite faces of the ring magnets thereby improving conversion efficiency.

[0076] The system and method thereof for conversion of low-grade thermal energy into electrical energy of the present invention according to plurality of embodiments allows conversion of low-grade heat to electricity. The system for conversion of low-grade thermal energy into electrical energy of the present invention according to plurality of embodiments can be manufactured using readily available materials.

[0077] According to a plurality of embodiments of the system and method thereof for conversion of low-grade thermal energy into electrical energy construction of MHD cells facilitate connection of multiple cells in series to increase the output.GVM-1

[0078] The system and method thereof for conversion of low-grade thermal energy into electrical energy of the present invention according to plurality of embodiments minimize the loss at the conversation of thermal energy to electrical energy and utilizes waste heat to produce the electrical energy thus conserving the lost energy in to a user friendly form.

[0079] Further, while one or more operations have been described as being performed by or otherwise related to certain modules, devices or entities, the operations may be performed by or otherwise related to any module, device or entity.

[0080] Further, the operations need not be performed in the disclosed order, although in some examples, an order may be preferred. Also, not all functions need to be performed to achieve the desired advantages of the disclosed system and method, and therefore not all functions are required.

[0081] While select examples of the disclosed system and method have been described, alterations and permutations of these examples will be apparent to those of ordinary skill in the art. Other changes, substitutions, and alterations are also possible without departing from the disclosed system and method in its broader aspects.

Claims

I / WE CLAIM:

1. A system for conversion of low-grade thermal energy into electrical energy, the system comprises: a casing having a hole in the centre of a top surface and a hole in the centre of a bottom surface through the thickness of the surfaces; a first ring type permanent magnate with a hole in the center placed interior to the inner top surface of the epoxy casing with its south pole placed flush at the inner top surface of the epoxy casing; a liquid entry side planar substrate with hole in the centre through the thickness of the liquid entry side planar substrate placed below the first ring type permanent magnate with a first surface forming upper surface of the liquid entry side planar substrate placed flush to the north pole of the first ring type permanent magnate; at least two gold plated copper tracks placed concentrically on a second surface forming lower surface of the liquid entry side planar substrate facing other side of the north pole of the first ring type permanent magnet; an upper nipple (10) housed through the hole in the top surface of epoxy casing and the hole in the liquid entry side planar substrate constituting a liquid entry pathway; a liquid exit side planar substrate having size smaller than the liquid entry side planar substrate placed spaced apart below the liquid entry side planar substrate; at least two gold plated copper tracks placed concentrically on a first surface forming upper surface of the liquid exit side planar substrate facing to the at least two gold plated copper tracks placed concentrically on second surface forming lower surface of the liquid entry side planar substrate; a plurality of separators placed between the second surface forming lower surface of the liquid entry side planar substrate and the first surface forming upper surface of the liquid exit side planar substrate, holding theliquid entry side planar substrate and the liquid exit side planar substrate spaced apart, maintaining a passage for liquid flow; a second ring type permanent magnate with a hole in the center placed flush to the liquid exit side planar substrate with its south pole flush to the lower surface of the liquid exit side planar substrate the other surface of liquid exit side planar substrate than the surface having the gold plated copper tracks; a liquid passage pathway is maintained between the north pole surface of the second ring type permanent magnet and the inner bottom surface of the epoxy casing; a bottom nipple (20) housed through hole in the bottom surface of the epoxy casing constituting a liquid exit pathway; and an ionic liquid, the ionic liquid selected based on its characteristics including electrical conductivity, electrochemical window, operating temperature range, specific heat, and circulated through the system.

2. The system as claimed in claim 1 wherein the hole in the centre of the top surface of the casing and the hole in the centre of liquid entry side planar substrate are concentrically aligned to house the upper nipple (10) configuring liquid entry path for the passage of the liquid3. The system as claimed in claim 1 wherein the first ring type permanent magnate and the second ring type permanent magnate are stronger magnates that produce higher emf for a smaller passage of ionic liquid, the magnets made up of materials like Neodymium compounds (NdFeB) providing flux density as high as 1 Tesla.

4. The system as claimed in claim 1 wherein the planar substrates comprising of: a substrate material having high electrical resistivity; a substrate material having high mechanical strength to withstand operating pressure and temperature conditions;GVM-1 a substrate material having very smooth surface finish for less resistance to flow of ionic liquid; planar substrate structure having thickness as thin as possible to minimize reluctance to magnetic flux; and a substrate material including Ceramics, Glass Epoxy etc.

5. The system as claimed in claim 1 wherein the outer gold plated copper track of the at least two gold plated copper tracks placed on each of the liquid entry side planar substrate and liquid exit side planar substrate acts as an Outer Electrode and the inner gold plated copper track of the at least two gold plated copper tracks placed on each of the liquid entry side planar substrate and liquid exit side planar substrate acts as an Inner Electrode.

6. The system as claimed in claim 1 wherein Diameters and thickness of the gold- plated copper tracks acting as Outer Electrode and Inner Electrode are identical (respectively) on both the planar substrates, the liquid entry side planar substrate and the liquid exit side planar substrate.

7. The system as claimed in claim 1 wherein the plurality of separators placed between the second surface forming lower surface of the liquid entry side planar substrate and the first surface forming upper surface of the liquid exit side planar substrate are preferably pieces of Teflon with thickness of 0.5 mm.

8. The system, as claimed in claim 1 wherein the casing having a hole in the center of the top surface and a hole in the center of a bottom surface through the thickness of the surfaces is an epoxy casing.

9. The system as claimed in claim 1 wherein the casing is preferably cylindrical in shape.

10. The system as claimed in claim 1 wherein the liquid entry side planar substrate and the liquid exit side planar substrate are preferably circular in shape.GVM-111. The system as claimed in claim 1 wherein ionic liquid passing through the upper nipple (10) connected to the centre of liquid entry side planar substrate, passing over inner electrodes of both the planar substrates then over outer electrodes of both the planar substrates, and flowing over liquid exit side planar substrate before exiting from the system through bottom nipple (20), the ionic liquid thus cutting through the magnetic field of the ring magnets through its movement in perpendicular direction to magnetic field, generating an EMF across the liquid, collecting this EMF across inner and outer electrodes and connecting to external electrical load.

12. The system as claimed in claim 1 wherein the velocity of laminar flow of ionic liquid passing through the magnetic field is a function of inlet pressure and gap between substrates.

13. The system as claimed in claim 1 wherein a potential of ionic liquid entering the cell is same as that of the inner electrode and a potential of ionic liquid exiting the cell is same as that of the outer electrode.

14. The system as claimed in claim 1 wherein preferably selected ionic liquid is 1- Butyl-3-methylimidazolium (BMIM) with Lithium Salts LiBF4 or LiPF6 having electrical conductivity: ~ 200 S / m i.e. resistivity of 0.005 ohm-meter, electrochemical window: ~ 4 Volts, specific heat: 1.26 J / g.K, and operating temperature range: -70° C to +192° C.

15. The system as claimed in claim 1 wherein a circulation pump used for ionic liquid circulation flow is of the type which provides electrical isolation between suction and discharge.

16. The system as claimed in claim 1 wherein reluctance of magnetic flux path is reduced by reducing the distance between poles of magnets i.e. by reducing the gap between the two planar substrates, use of thinner planar substrates such asGVM-1 ceramic substrates, and by providing a magnetic material between opposite faces of the ring magnets thereby improving conversion efficiency.

17. The system as claimed in claim 1 wherein system for conversion of low-grade thermal energy into electrical energy is configured to constitute a MHD cell.

18. A method for conversion of low-grade thermal energy into electrical energy, said method comprising steps of: transferring, by using heat exchanger and circulation pump heat from condenser to the ionic liquid; circulating, by a circulation pump an ionic liquid through the system for for conversion of low-grade thermal energy into electrical energy through an upper nipple; passing, the ionic liquid through the upper nipple (10) connected to the center of liquid entry side planar substrate; passing the ionic liquid over inner electrodes of a liquid entry side planar substrate and a liquid exit side planar substrate and then passing over outer electrodes of the liquid entry side planar substrate and the liquid exit side planar substrate; flowing the ionic liquid over liquid exit side planar substrate; exiting the ionic liquid from the system through bottom nipple (20); and collecting, across inner and outer electrodes an EMF generated and connecting to an external electrical load.

19. The method as claimed in claim 12 wherein during passing though the two planar substrates ionic liquid cuts through the magnetic field of the ring magnet.

20. The method as claimed in claim 12 wherein movement of ionic liquid is in perpendicular direction to the magnetic field.GVM-121. The method as claimed in claim 12 wherein EMF produced is proportional to the magnetic flux density and velocity of the ionic liquid.

22. The method as claimed in claim 12 wherein a potential of ionic liquid entering the cell is same as that of the inner electrode and a potential of ionic liquid exiting the cell is same as that of the outer electrode.

23. The method as claimed in claim 12 wherein circulation pump used for ionic liquid circulation flow is of the type which provides electrical isolation between suction and discharge.

24. The method as claimed in claim 12 further comprise step of reducing reluctance of magnetic flux path by reducing the distance between poles of magnets by reducing the gap between the two planar substrates, using thinner planar substrates such as ceramic substrates, and by providing a magnetic material between opposite faces of the ring magnets thereby improving conversion efficiency.

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