HEATING SYSTEMS AND METHODS

Abstract

 A heating system comprising: a liquid supply system; a cell configured to: receive liquid from the liquid supply system, provide heating thereof, and output heated fluid; a work extraction system configured to extract useable work from heated fluid output from the cell; wherein the cell comprises: (i) a housing arranged to define an internal portion for receiving liquid to be heated, and (ii) a plurality of electrodes configured to apply electrical energy to fluid in the internal portion; and wherein the electrodes are configured to apply electrical energy to said fluid in the internal portion to generate one or more bubbles of plasma for releasing energy into said fluid in the internal portion and the housing to provide heating of the fluid in the internal portion.

Description

Technical Field

[0001] The present disclosure relates to the field of systems and methods for generating heat. In particular, the present disclosure relates to systems and methods which use a cell to provide a heated fluid.

Background

[0002] Typically, the generation of power and/or heating may involve combustion of some sort of fuel. For instance, fossil fuels may be used in a combustion process which heats water to generate steam and/or hot water. Steam may be generated to be used for driving a turbine, and this in turn may be used to generate electricity. Hot water may be generated to be used in heating systems, where that hot water is circulated throughout a building to provide heating to that building. Electricity could also be used to generate warm water, such as in an electric boiler. It may be desirable to provide increased efficiency for such generation of power and/or heating.

Summary

[0003] Aspects of the disclosure are set out in the independent claims and optional features are set out in the dependent claims. Aspects of the disclosure may be provided in conjunction with each other, and features of one aspect may be applied to other aspects.

[0004] In an aspect, there is provided a heating system comprising: a liquid supply system; a cell configured to: receive liquid from the liquid supply system, provide heating thereof, and output heated fluid; a work extraction system configured to extract useable work from heated fluid output from the cell. The cell comprises: (i) a housing arranged to define an internal portion for receiving liquid to be heated, and (ii) a plurality of electrodes configured to apply electrical energy to fluid in the internal portion. The electrodes are configured to apply electrical energy to said fluid in the internal portion to generate one or more bubbles of plasma for releasing energy into said fluid in the internal portion and the housing to provide heating of the fluid in the internal portion.

[0005] Embodiments may enable the provision of a high exergy heated fluid from which work is extracted. Work may be extracted from this high exergy heated fluid to provide heating and/or power generation. Embodiments may provide an efficient system for generating heat and/or power. The cell may comprise a plasma cell (e.g. a plasma-generating fuel cell).

[0006] The system may further comprise a controller configured to: (i) receive a signal indicative of at least one operational parameter of the cell, and (ii) control operation of the heating system based on said operational parameter. The controller may be configured to control operation of the heating system so that heat and/or plasma generation in the cell is above a threshold level. Controlling operation of the heating system may comprise controlling at least one of: (i) the supply of liquid to the cell by the liquid supply system, and (ii) the electrical energy applied by the electrodes. The controller may be configured to control operation to keep at least one operational parameter for the cell within a selected range (e.g. to provide a selected level of performance for the cell).

[0007] The controller may be configured to control the supply of liquid to the cell and/or the electrical energy applied by the electrodes based on an obtained indication of demand for heating to be provided by the cell. In the event that the obtained indication of demand indicates increased demand for heating to be provided by the cell, the controller may be configured to increase at least one of: (i) the temperature of liquid supplied to cell, (ii) the pressure of liquid supplied to the cell, (iii) the amount of liquid supplied to the cell, and (iv) the amount of electrical energy applied by the electrodes. For example, controlling such operation may facilitate an increase in the output of the cell (e.g. to provide more heated fluid and/or plasma generation within the cell).

[0008] The signal indicative of at least one operational parameter may comprise an indication of a quality and/or quantity of plasma generation within the cell. The controller may be configured to control operation of the heating system so that the quality and/or quantity of plasma generation remains within a selected range. For example, the controller may be configured to provide at least a threshold amount of plasma generation. This threshold amount/selected range for plasma generation may be selected so that sufficient plasma generation is occurring to provide selected heating characteristics for the heating system (e.g. so that the amount of heated fluid generated is within a selected range).

[0009] The signal indicative of a quality and/or quantity of plasma generation may comprise an indication of at least one of: (i) a pressure and/or temperature of fluid output from the cell, (ii) an amount and/or type of electromagnetic energy present within the cell, (iii) chatter associated with supply of power to one or more of the electrodes, (iv) a current flow and/or voltage associated with one or more of the electrodes, and (v) fluid flow dynamics within the cell. For example, higher pressures and/or temperatures (e.g. for fluid output from the cell) may indicate increased plasma generation. Likewise, a higher rate of increase for pressure/temperature may indicate greater plasma generation. For example, an increase in any of: electromagnetic activity within the cell, and/or chatter associated with the supply of power may provide an indication of increased plasma generation. For example, sudden changes in current or voltage may provide an indication of any change in plasma generation. Where current begins to increase, this may provide an indication of arcing being about to occur. For example, the controller may be configured to reduce, or stop, the application of voltage to the first electrode in the event that a change in current exceeds a threshold value (or a rate of change of current exceeds a threshold), e.g. if the current is increasing too much. For example, voltage may be monitored to identify any drops in voltage, e.g. in response to arcing providing decreased resistance to current flow. For example, an indication of increased turbulence for fluid flow within the cell may provide an indication of increased plasma generation.

[0010] The controller may be configured to control at least one of: (i) the supply of liquid to the cell based on the electrical energy to be applied by the plurality of electrodes, and (ii) the electrical energy to be applied by the plurality of electrodes based on the supply of liquid to the cell. For example, when increasing the supply of liquid and/or electrical energy, the controller may control the supply of electrical energy/liquid (respectively) in accordance with the change to supply of the other. The change in supply of one may be selected based on the change of supply to the other (e.g. the increase/decrease in one may be selected in proportion to the increase/decrease in supply of the other). The signal indicative of at least one operational parameter may comprise an indication of a temperature associated with at least one of: the cell, the fluid in the cell, and the fluid output from the cell. The controller may be configured to control at least one of: (i) the electrical energy applied by the electrodes, (ii) the supply of liquid to the cell, and (iii) an external heater, to increase the temperature of the cell, the fluid in the cell, and/or the fluid output from the cell in the event that the indication of temperature is below a threshold level. The controller may be configured to increase the electrical energy applied by the electrodes to provide increased heating and/or decrease the flow rate of liquid through the cell in the event that the indication of temperature is below the threshold level.

[0011] An internal surface of the housing of the cell may comprise an electromagnetic energy-absorbing material arranged to convert incident photons into heat. At least a portion of the housing may be conductive. For example, the internal surface of the housing may be configured to generate heat in response to photons being incident on said surface. The housing (e.g. its internal surface) may be configured to heat the fluid within the internal portion in response to generating heat from incident photons (e.g. and/or other particles such aselectrons). The housing may be configured to provide conductive heating of the fluid within the internal portion. The housing may be made of metal, e.g. the housing may be made of steel. The housing may be formed of a plurality of different materials. One or more layers or sleeves may be provided to the housing. For example, the cell may include a sleeve located in the internal portion within the housing. The sleeve may be arranged to fit within the internal portion (e.g. it may sit adjacent to the internal portion of the housing). A plurality of such sleeves may be provided. Each sleeve may be arranged to provide different absorption/conduction properties to other regions of the housing/cell. For example, the housing may be made of a first material (e.g. steel), and a sleeve made of a second material (e.g. aluminium) may be inserted within the housing. The housing and/or sleeve may include a coating to further facilitate absorption and/or conduction. For example, a gold coating may be applied.

[0012] The liquid supply system may be configured to supply liquid to the cell under pressure. The cell may be arranged to retain fluid in the housing under pressure. For example, the housing may comprise one or more compression devices configured to retain the internal portion of the housing under pressure, and/or the housing may be sufficiently rigid to resist expansion under the pressure applied from inside the internal portion. The liquid supply system may be configured to heat liquid prior to supplying it to the cell. The liquid supply system may be configured to increase heating of liquid prior to supplying it to the cell in the event that heat and/or plasma generation of the cell is below a threshold level. The system may be arranged to provide a variable continuous supply of liquid to the cell.

[0013] The plurality of electrodes may comprise: (i) an anode arranged to provide a conductive path for current to be applied to fluid in the internal portion, and (ii) a cathode arranged to provide a conductive path away from the internal portion for current received from the anode through the fluid in the internal portion. The plurality of electrodes may further comprise a balancing electrode arranged to provide an additional conductive path towards or away from fluid in the internal portion. The anode and cathode (and e.g. balancing electrode) may be arranged concentrically with each other. The anode, cathode and balancing electrode may have the same coefficient of thermal expansion. The balancing electrode may be arranged away from the conductive path between the anode and the cathode. For example, the conductive path from the anode to the cathode may be radially outward. The balancing electrode may be offset from anode/cathode in a different direction (e.g. along a longitudinal axis). The balancing electrode may be closer to the anode than the cathode is. For example, the balancing electrode may run substantially perpendicular (e.g. perpendicular) to the current path from anode to cathode (e.g. it may be parallel to the anode).

[0014] The cell may comprise a resistive element arranged between the anode and cathode, for example the resistive element may comprise quartz or a bora-silicate glass material (e.g. a high resistance material which can withstand high temperatures and/or pressures). The resistive element may be of sufficient electrical resistance so that it may act as an electrical insulator. The resistive element may be arranged between on the conductive path between anode and cathode, e.g. to provide increased electrical resistance between anode and cathode. For example, the resistive element may be located radially outward from the anode, and radially inward from the cathode (e.g. where the conductive path from anode to cathode extends radially outward).

[0015] The system may be configured to provide additional heating to one or more components of the cell (e.g. during a start-up mode). The cell may comprise a heating element to provide such heating. For example, a heater may be located adjacent to the cell, and/or a heating element may be integrated within a part of the cell. A heater may be included in an end cap of the cell (e.g. a cartridge heater may be provided within an end cap of the cell). In some examples, this heating may be provided by a resistive heating element. The resistive heating element may be a part of the cell (e.g. voltage may be applied to a component such as anode or resistive element to provide resistive heating, or to an additional resistive heating element or region of the cell). Such heating may be provided to increase the temperature associated with at least one of: the cell, fluid inside the cell, and fluid output from the cell to the point where the plasma is stimulated. For example, heating may be provided until bubbles being to appear (e.g. gas bubbles).

[0016] The liquid supply system may be configured to supply a fluid to the cell, such as water, which at least partially exhibits non-Newtonian nature under circumstances to be expected within the cell. For example, wherein the liquid is configured to resist rapid expansion of plasma within the cell. The system may further comprise a filter apparatus configured to filter fluid output from the cell. The work extraction system may comprise at least one of: (i) a regulator for mass transfer of hot and/or pressurised fluid, (ii) a heat exchanger for transfer of heat to a working fluid, and (iii) a power generation system such as a steam-based power generation system. The heated fluid generated by the cell may itself be used for subsequent applications, or may instead be used for heating one or more other fluids for subsequent applications. For example, heated fluid generated by the cell may be used as a working fluid or heated fluid generated by the cell may be used to heat a separate fluid, which may then be used as a working fluid. The system may comprise a DC voltage source operable to apply a DC voltage to each of the electrodes.

[0017] In an aspect, there is provided a system comprising: a cell configured to heat liquid provided thereto, the cell comprising: an inlet for receiving a liquid to be heated, and an outlet for outputting heated fluid; a power management system configured to control application of electrical energy to the cell to control the heating of fluid in the cell; a work extraction system coupled to the outlet and configured to extract useable work from heated fluid output from the cell; and a fluid management system coupled to the inlet of the cell, and configured to: (i) supply liquid to be heated to the cell, and (ii) process heated fluid which has been output by the cell and used by the work extraction system.

[0018] The cell may comprise a cell as disclosed herein. The work extraction system may comprise a work extraction system as disclosed herein. The fluid management system may comprise a liquid supply system as disclosed herein, e.g. for supplying liquid to be heated to the cell.

[0019] The fluid management system may comprise: (i) a liquid supply coupling for coupling the system to a supply of liquid to be heated, and (ii) a drain coupling for discarding heated fluid which has been output by the cell and used by the work extraction system. The fluid management system may comprise a pump coupled to the liquid supply coupling and the inlet of the cell, wherein the pump is operable to supply liquid to the cell under pressure. The work extraction system may comprise a heat engine. The outlet of the cell may be coupled to a first engine inlet to enable heated fluid output from the cell to drive the engine. The heat engine may be coupled to a generator configured to generate power in response to driving of the engine. The outlet of the cell may also be coupled to a first heat exchanger. A first engine outlet may be coupled to the first heat exchanger so that heated fluid from the cell which has passed through the engine is directed to the first heat exchanger for heating. The first heat exchanger may be coupled to a second engine inlet to enable reheated fluid from the heat exchanger to further drive the engine. The engine may be arranged to be driven at a different ratio for fluid entering through the first and second engine inlets. At least one of the engine and the first heat exchanger may be coupled to a second heat exchanger configured for further extracting heat from the heated fluid output from the cell.

[0020] The fluid management system may comprise a filter for filtering heated fluid which output from the cell. The work extraction system may comprise at least one of: a heat management system configured to receive heated fluid which has been output from the cell, and to use said heated fluid as a heat source or in a heat exchanger; and a power generation system configured to receive heated fluid which has been output from the cell, and to use said heated fluid to generate power. The power generation system may be coupled to the power management system to provide generated power thereto. The power management system may comprise an external coupling for coupling to an external source of power. The power management system may be configured to receive power from the external source and/or provide power generated by the power generation system to the external source.

[0021] In an aspect, there is provided a method of providing a heated fluid for extracting useable work therefrom, the method comprising: supplying a liquid to be heated to a cell, wherein the cell comprises: (i) a housing arranged to define an internal portion for receiving the liquid to be heated, and (ii) a plurality of electrodes configured to apply electrical energy to fluid in the internal portion; controlling operation of the plurality of electrodes to apply electrical energy to fluid in the internal portion to generate one or more bubbles of plasma; generating heat in the housing proximal to the internal portion in response to the housing receiving incident photons (e.g. and also electrons) associated with plasma bubbles in the internal portion; using the housing to conductively heat fluid in the internal portion.

[0022] In an aspect, there is provided a method of controlling operation of a heating system, the heating system comprising a cell comprising: (i) a housing arranged to define an internal portion for receiving liquid to be heated, and (ii) a plurality of electrodes configured to apply electrical energy to fluid in the internal portion, the method comprising: controlling operation of the electrodes to apply electrical energy to fluid in the internal portion to generate one or more bubbles of plasma for releasing energy from the plasma into the fluid in the internal portion and the housing to provide heating of the fluid in the internal portion, wherein controlling operation of the electrodes comprises: receiving a signal indicative of at least one operational parameter associated with the cell and/or a fluid associated therewith; operating in a 'cold-start' mode when the operational parameter indicates heating and/or plasma generation is below a threshold level; and operating in a 'normal' mode when the operational parameter indicates heating and/or plasma generation is above the threshold level; wherein operating in the cold-start mode comprises controlling at least one of: (i) the electrical energy applied by the electrodes, (ii) supply of liquid to the cell, and (iii) operation of an external heater, to increase the temperature of the cell and/or the fluid associated therewith in the event that the operational parameter indicates heating and/or plasma generation is below a threshold level.

[0023] Aspects of the present disclosure may also provide one or more computer program products comprising computer program instructions configured to control a processor to perform any of the methods disclosed herein.

Figures

[0024] Some examples of the present disclosure will now be described, by way of example only, with reference to the figures, in which:

Fig. 1 shows a schematic diagram of an exemplary heating system.

Fig. 2 shows a schematic diagram of an exemplary heating system.

Fig. 3 shows a schematic diagram of an exemplary cell.

Fig. 4 shows a block diagram of an exemplary heat and power generating system.

Fig. 5 shows a schematic diagram of an exemplary heat and power generating system.

[0025] In the drawings like reference numerals are used to indicate like elements.

Specific Description

[0026] Embodiments of the present disclosure are directed to systems for generating heat and/or power. Such systems may provide heating of a liquid to produce a heated fluid.. The heated fluid may then be used for heating purposes and/or for power generation purposes. To generate the heated fluid, liquid may be supplied to a cell. Electrical energy may be applied to liquid held in the cell via one or more electrodes of the cell. The application of this electrical energy to the fluid within the cell causes gas bubbles within the cell to form plasma bubbles. Each bubble of plasma will be a localised region having a higher pressure/temperature than its surrounding fluid. The surrounding fluid may limit expansion of the plasma bubbles so that, as electrical energy is still applied, these bubbles will emit electromagnetic energy. For example, photons may be emitted from atoms (or molecules) within the plasma bubbles. In turn, these emitted photons may heat up the substance on which they are incident. For instance, this may provide heating of the housing of the cell and/or fluid within the cell. In turn, this enables the cell to output a heated fluid for using in a heating and/or power generation system 500. The heated fluid may contain liquid and/or gas, and in some cases, the heated fluid may also contain some plasmatic materials.

[0027] An exemplary heating system will now be described with reference to Fig. 1.

[0028] Fig. 1 shows a schematic diagram of a heating system 50. The heating system 50 includes a liquid supply system 10, a cell 100 and a work extraction system 20. The cell 100 includes a fluid inlet 12 and a fluid outlet 22. The cell 100 has a housing 120 which defines an internal portion 125 of the cell 100. The cell 100 also includes a plurality of electrodes, which, as shown, includes a first electrode 111 and a second electrode 112. The cell 100 may comprise a plasma cell (e.g. a plasma-generating fuel cell).

[0029] The housing 120 of the cell 100 encapsulates the internal portion 125. The fluid inlet 12 provides a flow path for fluid into the internal portion 125 of the cell 100. The fluid outlet 22 provides a flow path for fluid out from the internal portion 125 of the cell 100. The internal portion 125 of the cell 100 may otherwise be sealed by the housing 120. The liquid supply system 10 is coupled to the fluid inlet 12 of the cell 100. The work extraction system 20 is coupled to the fluid outlet 22 of the cell 100. The couplings between the liquid supply system 10 and the fluid inlet 12, and the work extraction system 20 and the fluid outlet 22 are shown as an annular flow path. However, it will be appreciated that this is purely for illustrative purposes, and any suitable flow path may be provided). Also, although not shown in the Figs., the work extraction system 20 may also be coupled to the liquid supply system 10 (e.g. to facilitate heating and/or pressurising of liquid to be supplied to the internal portion 125).

[0030] The first electrode 111 is at least partially disposed within the internal portion 125 of the cell 100. The second electrode 112 may also be disposed at least partially within the internal portion 125 of the cell 100. The first and second electrode 112 are arranged concentrically. The first electrode 111 extends within a central region of the internal portion 125 of the cell 100. The second electrode 112 is arranged radially outward from the first electrode 111. The second electrode 112 may be cylindrical, as may the first electrode 111. The first and second electrode 112 are arranged co-axially in the example shown in Fig. 1. The second electrode 112 is located adjacent to an internal surface of the housing 120 (however in some examples, the second electrode 112 may be integrated with the housing 120, e.g. to form a part thereof, and/or a portion of the housing 120 may provide the second electrode 112, e.g. if said portion of the housing is electrically conductive).

[0031] A first end of the first electrode 111 is located outside the internal portion 125 of the housing 120. A second end of the first electrode 111, distal to the first end, is located within the internal portion 125 of the housing 120. The second electrode 112 may extend along some, or all, of the length of the internal portion 125 of the housing 120. At least one end of the second electrode 112 may extend out of the internal portion 125 of the cell 100. Although not shown in Fig. 1 the first and/or second electrode 112 may each be coupled to a power supply. For example, each electrode may have one end which extends outside the internal portion 125 (e.g. into the housing 120), and this end may be coupled to the power supply. In some examples, the housing 120 may provide a ground, and the first electrode 111 may be connected to a positive terminal of the power supply.

[0032] The housing 120 may be cylindrical. The fluid inlet 12 is arranged at an opposite end of the housing 120 to the fluid outlet 22. The first and second electrode 112 extend along an axis extending from the fluid inlet 12 to the fluid outlet 22 (e.g. a longitudinal axis of the cell 100). The fluid outlet 22 may be arranged vertically higher (e.g. above, such as directly above) the fluid inlet 12.

[0033] The liquid supply system 10 is arranged to supply liquid to the cell 100. Liquid may be provided into the cell 100 through the fluid inlet 12. The liquid supply system 10 may comprise a coupling to a liquid supply, such as a reservoir of liquid. The liquid supply system 10 is configured to control delivery of this liquid to the cell 100. For example, the liquid to be supplied may comprise partly or wholly a fluid which exhibits non-Newtonian behaviour in the environment of the cell 100. The liquid may be water or an aqueous solution.

[0034] The work extraction system 20 is arranged to receive heated fluid from the cell 100. Heated fluid may be output from the cell 100 through the fluid outlet 22. The heated fluid may comprise liquid and/or gas. For example, this may be a combination of gas and liquid - e.g. steam with some water droplets. The fluid outlet 22 is arranged to enable flow of this heated fluid out from the cell 100 to be used by the work extraction system 20. For example, steam created within the cell 100 may rise up and out through the fluid outlet 22. The work extraction system 20 is configured to utilise the heated fluid output from the cell 100. The work extraction system 20 may be configured to receive this heated fluid, and to use this as part of a supply of heated fluid (e.g. for heating purposes). The work extraction system 20 may be configured to receive this heated fluid, and to use this heated fluid for generation of power. For example, this heated fluid may be used to drive a generator, e.g. through use of a steam engine.

[0035] The housing 120 is configured to encapsulate the internal portion 125. The housing 120 is arranged to define the internal portion 125 to provide a region in which liquid may be heated. An internal surface of the housing 120 (e.g. which faces/defines the internal portion 125) may be configured to generate heat in response to incident photons (for example, the housing 120 may be conductive). The internal surface may comprise the region of the housing 120 which lies adjacent to the internal portion 125. This may comprise part of the housing 120 and/or it may comprise an additional component, such as a layer/film provided there to generate heat in response to incident photons. For example, the internal surface may be configured to absorb electromagnetic energy, such as in the form of visible light. The internal surface is configured to heat up as it receives incident photons. The internal surface is configured to provide heating of fluid within the internal portion 125, e.g. as it heats up from incident photons. The housing 120 may be made of a metal, such as steel. The housing 120 is configured to retain fluid in the internal portion 125 under pressure.

[0036] The fluid inlet 12, the internal portion 125, and the fluid outlet 22 are arranged to define a flow path for fluid to flow through the internal portion 125 of the housing 120. The internal portion 125 is arranged to receive liquid to be heated through the fluid inlet 12. The cell 100 is arranged to heat this liquid in the internal portion 125 to provide a heated fluid. The fluid outlet 22 is arranged to provide a flow path for this heated fluid away from the internal portion 125.

[0037] The first and second electrodes 111, 112 are configured to provide a current flow path through the internal portion 125 of the cell 100. One of the electrodes 111, 112 may provide an anode, and the other may provide a cathode. For instance, the first electrode 111 may provide the anode for bringing current into the internal portion 125 of the cell 100. The second electrode 112 may then provide the cathode for carrying current away from the internal portion 125 of the cell 100. The first and second electrode 112 are spaced apart from each other. The first electrode 111 is arranged to receive a voltage so that a potential difference exists between the first and second electrodes 111, 112. The first and second electrodes 111, 112 are arranged capacitively. The presence of fluid in the internal portion 125 may provide a conductive path between the first and second electrode 112. The fluid will provide electrical resistance between the two electrodes 111, 112. The first and second electrode 112 with fluid in the cell 100 may effectively provide a circuit having a capacitance and a resistance. The first and second electrodes 111, 112 are configured to provide a voltage stress to fluid and/or plasma within the internal portion 125.

[0038] In operation, the liquid supply system 10 supplies a liquid through the fluid inlet 12 and into the internal portion 125 of the cell 100. In this example, the liquid will be water, but other liquids may be used. The liquid supply system 10 operates to supply water to the cell 100 so that the cell 100 fills up with water. Any gas previously in the cell 100 may be forced out through the fluid outlet 22 of the cell 100. The cell 100 may then be substantially filled with water.

[0039] A voltage is applied to the first electrode 111 (anode). This will cause some current flow into the water. Due to the electrical resistance of water, this current flow and resistance will cause some heating of the water (e.g. I²R heating). This process of resistive heating continues as a voltage is applied to the first electrode 111. As the temperature of the water within the internal portion 125 rises, microbubbles of gas will start to form within the water in the internal portion 125. These may be steam bubbles forming or bubbles of air being released which were trapped in the water supplied to the internal portion 125 of the cell 100. As a result, some pockets of gas will develop within the liquid in the internal portion 125 of the cell 100. With continued application of the voltage to the first electrode 111, bubbles of plasma will be generated within the internal portion 125 of the housing 120. These bubbles will release energy into the surrounding fluid and the internal surface of the housing 120. In turn this provides heating of the fluid within the internal portion 125.

[0040] Without wishing to be bound by theory, by applying the voltage to the first electrode 111, this will charge up the capacitor provided by the first and second electrode 112. As the fluid within the internal portion 125 heats up, its permittivity may change, and this may change a capacitance of the cell 100 (e.g. between the first and second electrodes 111, 112). For example, when water is used, its permittivity will decrease as it heats up (and then also when it becomes steam). In particular, where microbubbles of gas (e.g. steam) begin to form within the liquid in the internal portion 125, these will provide localised regions of lower permittivity. This process may effectively provide a permittivity collapse in localised regions. For example, where water is used, this difference in permittivity between bubbles forming in the water and the surrounding water may be a factor of approximately 40 (e.g. the capacitance per unit volume in those bubbles may be 1/40^th of that of the surrounding water). During this process, the volumetric energy density for fluid and/or plasma within the internal portion 125 will remain constant. Due to the permittivity collapse within the bubbles of gas, capacitance will decrease in this region. As the volumetric energy density remains constant and the capacitance decreases, the voltage per meter will rise accordingly (e.g. to conserve energy as per E=1/2 CV²). For examples where water is used, the voltage per meter will rise by a factor of approximately √40.

[0041] Without wishing to be bound by theory, with electrical energy still being applied to the first electrode 111, these microbubbles of gas (at lower density than surrounding liquid) will try to rapidly expand into their surroundings. However, the surrounding liquid will resist this expansion, e.g. due to the non-Newtonian nature of the liquid in these conditions. This will cause the microbubbles to rapidly increase in temperature and pressure. In turn, their capacitance will further decrease (e.g. causing an increased dV/dr), thereby giving rise to further increased voltage stress across the bubble. With sufficient voltage stress across the bubble, ionization may occur leading to the formation of plasma within the bubble. Thus, one or more plasma bubbles may form in the liquid in the internal portion 125. The plasma may be at an even lower density than the gas, and so with a voltage still applied to the first electrode 111, the plasma bubble will further try to rapidly expand. In particular, this process of plasma bubble generation will occur rapidly, and so each bubble of plasma will drive for rapid expansion. In turn, this will bring about non-Newtonian fluid responses in the liquid in the internal portion 125 of the cell 100. For instance, where water is used, the water does not immediately yield before the pressure wave brought about by the bubble of plasma trying to expand. The bubble of plasma is therefore held in a relatively fixed volume (e.g. it may only expand relatively slowly). While the volume of the plasma remains relatively constant, the temperature and pressure within this bubble rise rapidly in response to the voltage stress brought about by the voltage applied to the first electrode 111.

[0042] Without wishing to be bound by theory, to accommodate this high level of energy within the plasma bubble, energy may be absorbed by atoms (and molecules) within the bubble. The energy levels (e.g. states) of these particles may therefore rise. Within the plasma, atoms may have their electrons move to higher electron energy levels, and/or spin states for these particles may change. For example, Hydrogen atom spin states may change from their lower energy para-state to their higher energy ortho-state. Molecules may also move to higher rotational and/or vibrational energy levels, and/or further splitting up of these molecules may occur. As a result, the atoms within each bubble will be at disproportionately high energy levels (e.g. as compared to conventional fluids/the fluid within the internal portion 125).

[0043] Without wishing to be bound by theory, photon emission from the plasma may occur to accommodate for the high energy within the plasma. Electrons may move to lower energy electron states, and/or changes to lower energy vibrational/rotational/spin states may occur for atoms/molecules. It is this returning to lower energy configurations which gives rise to the emission of photons (e.g. to accommodate for the drop in energy levels as per the Bohr model). This emission of photons may occur on a relatively large scale. Where water is used, a large proportion of this photon emission occurs in the visible light spectrum.

[0044] The photons emitted from each plasma bubble will then be absorbed by either fluid in the internal portion 125 or the housing 120 of the cell 100. In response to receiving such incident photons, the fluid and/or housing 120 will heat up as it absorbs said photons. The inner surface of the housing 120 in particular may absorb a large number of these photons and thus increase in temperature. As the inner surface of the housing 120 heats up, it will in turn provide conductive heating of the fluid within the internal portion 125. This may give rise to convection currents occurring and thus increased turbulence for fluid within the internal portion 125 of the cell 100. As a result of this process, the fluid within the internal portion 125 will heat up. The majority of the liquid provided to the internal portion 125 of the cell 100 may then evaporate to provide a gas (e.g. steam). It is to be appreciated in the context of the present disclosure that some of the fluid which exits the cell 100 may have somewhat unconventional, or at least lower energy configurations, as compared to the liquid that was provided to the cell 100. This is as a consequence of the plasma generation and subsequent energy release which occurred within the cell 100.

[0045] This heated fluid then passes through the fluid outlet 22. Typically, the heated fluid is in the form of steam, which is generated within the internal portion, and which rises up and out through the fluid outlet 22. The heated fluid is then used in the work extraction system 20 to extract useable work from the heated fluid. For instance, this heated fluid may be used for power generation and/or heat distribution.

[0046] Further examples of the present disclosure will now be described with reference to Fig. 2.

[0047] Fig. 2 shows a schematic diagram of a heating system 50. As with Fig. 1, the heating system 50 of Fig. 2 includes a liquid supply system 10, a cell 100 and a work extraction system 20. These components of the heating system 50 of Fig. 2 are similar to those of Fig. 1, e.g. features of the heating system 50 of Fig. 1 could be used in combination with features of the heating system 50 of Fig. 2.

[0048] The liquid supply system 10 may additionally include a liquid reservoir 14, a heater 16 and a pump 18. The cell 100 includes fluid inlet 12, fluid outlet 14, and housing 120 which defines an internal portion 125. The cell 100 includes first electrode 111 and second electrode 112. Also, as shown in Fig. 2, the cell 100 may include a third electrode 113 and a resistive element 115. The cell 100 may comprise a plasma cell (e.g. a plasma-generating fuel cell).

[0049] The heating system 50 may also include a power supply 30 and a controller 40. A plurality of sensors are shown by black circles to illustrate possible sensing capabilities of the system 50. The sensors shown include a power supply sensor 41, a fluid inlet sensor 42, a first electrode sensor 43, a second electrode sensor 44, and third electrode sensor 45, a fluid outlet sensor 46, and an internal portion sensor 47.

[0050] The liquid supply system 10 may couple the liquid reservoir 14 to the fluid inlet 12 of the cell 100. The liquid reservoir 14 may be coupled to the fluid inlet 12 via the pump 18 and/or the heater 16 (both are shown in Fig. 2). The liquid supply system 10 is configured to provide liquid to the internal portion 125 of the cell 100. The liquid supply system may supply liquid from a source of liquid, such as the liquid reservoir 14 shown in Fig. 2, or it may comprise a coupling to a liquid supply, e.g. a mains water supply, for supplying liquid.

[0051] The first and second electrode 112 may be arranged within the cell 100 as described above with reference to Fig. 1. Additionally, the third electrode 113 is also provided in the internal portion 125 of the cell 100. The third electrode 113 is optional, and may or may not be included. When included, a first end of the third electrode 113 may be located outside the internal portion 125, and the third electrode 113 may extend form the first end to a second end located within the internal portion 125. The second end of the third electrode 113 may be located proximal to the second end of the first electrode 111 within the internal portion 125. The first and third electrodes 111, 113 may be parallel (e.g. they may be co-axial). The second and third electrodes 112, 113 may be parallel (e.g. coaxial). The first electrode 111 may extend from outside a first end of the housing 120 into the internal portion 125 towards an opposite end of the housing 120. The third electrode 113 may extend from outside the opposite end of the housing 120 into the internal portion 125 towards the first end. The first and third electrodes 111, 113 may extend into the internal portion 125 so that there is no spatial overlap between these electrodes 111, 113 (e.g. their respective second ends do not touch/overlap). The second electrode 112 may extend along the length of the internal portion 125 from at or outside the first end to at or outside the opposite end. The distance between the second end of the first electrode 111 and the second end of the third electrode 113 may be less than the smallest distance between the first electrode 111 and the second electrode 112. The third electrode 113 may be located away from an expected current path between the first and second electrode 112.

[0052] A resistive element 115 may also be included in the internal portion 125. The resistive element 115 may also be cylindrical. The resistive element 115 may be arranged to increase the electrical resistance of the conductive path between the first electrode 111 (anode) and the second electrode 112 (cathode). The resistive element 115 may extend around a majority of the internal portion 125 (e.g. along a length and width of the internal portion to impede the majority of possible conductive paths from anode to cathode). The resistive element 115 may be located between the first/third and second electrodes 111, 112. For example, the resistive element 115 may be located radially outward from the first/third electrodes 111, 113, but not as far radially outward than the second electrode 112. The resistive element 115 may extend along some or all of the length of the internal portion 125. The resistive element 115 may be arranged on a current flow path between the first electrode 111 and the second electrode 112, e.g. so that current would need to flow through the resistive element 115 to get from the first electrode 111 to the second electrode 112. The resistive element 115 may extend along one or both of the ends of the internal portion 125 (e.g. to reduce the likelihood of a conductive path from anode to cathode not via the resistive element 115 being possible).

[0053] The power supply 30 may comprise a DC supply (e.g. there may be an AC to DC converter for providing DC). The power supply 30 may be coupled to one or more components of the heating system 50. Fig. 2 illustrates a number of these possible couplings with solid lines. For example, these may comprise some form of conductor to provide a conductive coupling from the power supply 30 to said component. The power supply 30 may be coupled to the first electrode 111, and/or any of the second electrode 112, or third electrode 113. The cell 100 may also include a heater, such as a resistive heater (e.g. a cartridge heater). The power supply may also be coupled to the heater. The power supply 30 could be coupled to the resistive element 115 (e.g. to provide resistive heating), as shown in Fig. 2. However, it is to be appreciated that the resistive element need not be coupled to the power supply. Instead, it may be included only to increase resistance between first and second electrodes 111, 112.

[0054] The controller 40 may be coupled to each of the sensors. The controller 40 may also be coupled to one or more of the power supply 30, the heater 16 and the pump 18. Fig. 2 illustrates these couplings with dashed lines. These couplings may be wired or wireless.

[0055] The liquid supply system 10 is configured to supply liquid to the internal portion 125 of the cell 100. The controller 40 may be configured to control operation of the liquid supply system 10. For example, the liquid supply system 10 may selectively heat (using the heater 16) and/or pressurise (using the pump 18) liquid from the liquid reservoir 14 which is to be provided to the internal portion 125 of the cell 100. The controller 40 may be configured to control operation of the heater 16 and/or pump 18 to control the temperature and/or pressure of the liquid supplied to the cell 100.

[0056] The power supply 30 may be configured to apply a voltage to the first electrode 111 (e.g. to provide the operation described above with reference to Fig. 1). The power supply 30 may also be configured to apply a voltage to the third electrode 113 (and/or e.g. a heater of the cell 100). The power supply 30 may also be coupled to the second electrode 112 to receive a current carried away therefrom. The power supply 30 may be configured to selectively apply a voltage, e.g. using high voltage DC. The controller 40 may be configured to control operation of the power supply 30. For example, the controller 40 may be configured to control at least one of: a magnitude of voltage applied by the power supply 30, timing for the voltage supply, and/or the components to which voltage is being applied.

[0057] The third electrode 113 may be active or passive. When active, a voltage is applied to the third electrode 113. When passive, the third electrode 113 may be conductive for receiving current within the internal portion 125, but without receiving power from the power supply 30. The third electrode 113 may be configured to provide a balancing electrode (e.g. it may be arranged to balance electric field/current generated within the internal portion 125). The controller 40 may be configured to control operation of the power supply 30 to selectively control whether (and/or how much) voltage is applied to the third electrode 113.

[0058] The resistive element 115 may be configured to be of relatively high resistance (e.g. as compared to the resistance of the electrodes and/or fluid within the internal portion 125). The resistive element 115 may be of sufficient resistance to effectively provide an electrical insulator (between the anode and cathode).

[0059] In examples, the cell includes a heater configured to provide heating in response to application of a voltage thereto, e.g. to provide resistive (I²R) heating. The heater could be a region of the housing, or a separate component configured to provide resistive heating (e.g. which may be integrated into a part of the housing, such as an end cap). The heater could be arranged to provide heating of the fluid in the internal portion 125 and/or the housing 120 in response to application of a voltage thereto. The controller 40 may be configured to control operation of the power supply 30 to selectively control whether (and/or how much) voltage is applied to the heater. In some examples, the heater could be provided by the resistive element 115.

[0060] The controller 40 may be configured to receive a signal indicative of at least one operational parameter of the operation of the cell 100. The controller 40 may be configured to control operation of the heating system 50 based on this received signal. For example, the controller 40 may be configured to control operation of at least one of the heater 16, the pump 18, and/or the power supply 30 based on the received signal. The controller 40 may be configured to control the heat and/or pressure of liquid supplied to the internal portion 125.

[0061] The controller 40 may be configured to control whether and/or how much voltage is applied to one or more of the first electrode 111, the third electrode 113 and/or the heater. In other words, the controller 40 may be configured to control the supply of liquid to the internal portion 125 of the cell 100 and/or the electrical energy to be applied by electrodes of the cell 100.

[0062] The controller 40 may be configured to control operation based on at least one received signal indicative of one or more operational parameters of the cell 100. The signal may be received from one or more of the sensors. It is to be appreciated that the exact nature of the signal received, and/or the sensor from which it is received is not to be considered limiting. Exemplary sensors are shown in Fig. 2, which may provide information indicative of one or more operational parameters of the system 50.

[0063] The power supply sensor 41 may be configured to provide an indication of operation of the power supply 30. The power supply sensor 41 may be configured to provide an indication of a magnitude of power (e.g. voltage) being applied, and/or it may provide any relevant feedback on the signal being applied by the power supply 30. For example, the power supply sensor 41 may be configured to provide an indication of any chatter associated with the voltage being applied by the power supply 30 (e.g. to the first sensor). The fluid inlet sensor 42 may be configured to provide an indication of at least one property of the liquid to be supplied to the internal portion 125. For example, this may comprise an indication of a pressure and/or a temperature of the liquid to be supplied. As another example, the fluid inlet sensor 42 may be configured to provide an indication of one or more chemical properties of the liquid to be supplied to the internal portion 125 (e.g. indicative of the chemical composition of said liquid, such as percentage of impurities/additives etc.). The fluid outlet sensor 46 may be similar to the fluid inlet sensor 42. For example, the fluid outlet sensor 46 may be configured to provide an indication of a temperature, pressure and/or chemical composition of fluid being output from the cell 100. The fluid outlet sensor 46 may be configured to provide an indication of any relevant energy configuration changes to the fluid exiting the cell 100 (e.g. whether any additional compositions are present).

[0064] The first electrode sensor 43, the first electrode sensor 44 and the third electrode sensor 45 may be configured to provide an indication of one or more properties of the relevant electrical energy present thereat. The sensors may provide an indication of a voltage and/or current present at the relevant electrode. For example, an electrode sensor may be configured to provide an indication of how current and/or voltage at said electrode varies with time (e.g. to provide an indication of a time derivative for the current/voltage).

[0065] The internal portion sensor 47 is configured to provide an indication of the conditions within the internal portion 125 of the cell 100. The internal portion sensor 47 may be located within the internal portion 125 of the housing 120, e.g. it may be attached to an internal wall of the housing 120 (as shown in Fig. 2). Alternatively, the internal portion sensor 47 may be located outside the external portion but configured to provide some indication as to the conditions within the internal portion 125. The internal portion sensor 47 may be configured to provide an indication of fluid flow dynamics within the internal portion 125 - e.g. to provide an indication of whether there is any turbulent flow, and/or how turbulent the flow is. This could include use of a flow meter, a microphone, or any other suitable sensor. The internal portion sensor 47 may be configured to provide an indication of electromagnetic energy present inside the internal portion 125 (e.g. an indication of the amount and/or type of electromagnetic emission occurring). For example, the internal portion sensor 47 may comprise a suitable antenna to detect the presence of such electromagnetic energy/emissions, and/or it may comprise some form of camera (e.g. as part of a fibre optic) configured to obtain an indication of light present in the cell 100. The internal portion sensor 47 may be configured to provide an indication of the state of activity occurring inside the cell 100.

[0066] In operation, the heating system 50 of Fig. 2 functions in much the same manner as the heating system 50 described above with reference to Fig. 1. That is, the power supply 30 applies electrical energy (e.g. a voltage) to the first electrode 111 to heat the fluid in the internal portion 125. This heating is brought about by resistive heating and also heating from incident light emitted from bubbles of plasma within the internal portion 125. Additionally, a capacitance may be provided between the first and third electrode 113, and/or between the second and third electrode 113. This may provide a balancing effect to the electric field within the internal portion 125 of the cell 100. The third electrode 113 may provide a balancing effect if provided as a floating electrode (e.g. in a passive state) and if a voltage is applied to the third electrode 113 (e.g. in an active state).

[0067] Additionally, the controller 40 may be configured to control operation of the heating system 50 according to any of a number of different control loops. Each control loop may provide a feedback loop in which data indicative of an operational parameter of the cell 100 is obtained (e.g. from a sensor), and the controller 40 controls operation of a component of the heating system 50 based on this obtained data. The data may be obtained from any suitable sensor (e.g. any of the sensors shown in Fig. 2 and described above). The controller 40 may control operation of any suitable component of the heating system 50, such as controlling the supply of liquid to the internal portion 125 of the cell 100 (e.g. controlling the heater 16 or the pump 18), and/or controlling the electrical energy to be applied by one or more of the electrodes (e.g. controlling the power supplied by the power supply 30).

[0068] Four exemplary control loops will now be discussed. In a first example, operation of the cell 100 will be described in a 'normal' mode, where at least one property is monitored and/or regulated to provide increased efficiency for operation of the cell 100. In second and third example, operation of the cell 100 will be described for increasing and decreasing cell 100 output respectively. In a fourth example, operation of the cell 100 will be described when in a 'start-up' mode.

[0069] In the first example, operation of the heating system 50 is controlled in a normal mode of continued operation. Here, the controller 40 is configured to receive a signal indicative of an operational parameter of the cell 100, and the controller 40 is configured to control operation of the system 50 so that the operational parameter remains within a desired range for performance of the cell 100. The cell 100 is designed to provide heated fluid as its output. The operational parameter may therefore provide an indication of the output for the cell 100. For example, the operational parameter may provide an indication of how efficiently the cell 100 is performing and/or an indication of the magnitude of heat generation being provided by the cell 100 (e.g. it may provide an indication of the amount/temperature of heated fluid being generated by the cell 100 per unit time). It will be appreciated in the context of the present disclosure that the cell performance need not be determined per se., but instead, the controller 40 may control operation of the cell 100 based on an indicator of cell performance.

[0070] The controller 40 may be configured to receive an indication of cell performance. The indication of cell performance may provide an indication of the operating state of the cell 100. This may comprise an indication of the amount/temperature of heated fluid being generated by the cell 100 and/or an indication of the quality of plasma generation occurring within the cell 100. The indicator may be based on a temperature and/or pressure of heated fluid being generated by the cell 100 (e.g. it may be an indication of said temperature and/or pressure). For example, such an indication may be obtained using the fluid outlet sensor 46. The indication may be based on both the temperature/pressure of liquid being provided to the cell 100 (e.g. as sensed by the fluid inlet sensor 42) and the temperature/pressure of heated fluid exiting the cell 100 (e.g. as sensed by the fluid outlet sensor 46). The indication may be based on an amount of heating being provided by the cell 100 (e.g. a difference between inlet and outlet temperatures), and/or a rate of heating being provided by the cell 100.

[0071] As an example, the controller 40 may be configured to receive a signal indicative of a temperature of the heated fluid leaving the cell 100. In the event that the heated fluid is outside a selected range (e.g. above an upper threshold temperature and/or below a lower threshold temperature), the controller 40 may control operation of the heating system 50 to increase/decrease the temperature, as appropriate, for the outlet temperature to return to within the selected range. This may further comprise the controller 40 determining if the liquid provided to the cell 100 is heated by above a threshold amount and/or within a threshold time period. The controller 40 may control operation of the heating system 50 so that a sufficient amount of heating and/or sufficiently quick heating occurs.

[0072] In addition, or as an alternative, to receiving a direct indication of a temperature/pressure of heated fluid leaving the cell 100, the controller 40 may receive a signal which is indicative of cell performance. For example, the controller 40 may receive a signal indicative of an amount and/or quality of plasma generation occurring within the cell 100. The controller 40 may control operation of the heating system 50 to so that the quantity and/or quality of plasma generation occurring is within a selected range. In turn, this may act to control the generation of heated fluid by the cell 100, as the generation of plasma within the cell 100 ultimately gives rise to heating of the fluid within the cell 100.

[0073] The controller 40 may be configured to obtain an indication of a property of plasma generation within the cell 100 based on a received signal from a sensor. The indication of the property of plasma generation may be determined based on temperature and/or pressure data for fluid entering and/or leaving the cell 100. The amount of plasma generation may be determined based on the amount of heat generation, and/or the speed with which fluid is being heated. For example, quicker/more heating may indicate more plasma generation. The controller 40 may be configured to determine that plasma generation is within a selected range in the event that the amount and/or rate of heating by the cell 100 is within a selected range.

[0074] The amount of plasma generation may be determined based on an obtained indication of the conditions inside the internal portion 125 of the housing 120 (e.g. using the internal portion sensor 47). An indication that fluid within the internal portion 125 is moving turbulently may indicate more plasma generation (e.g. due to more conduction heating being provided by the inner portion of the housing 120, and this giving rise to convection currents). Alternatively, or additionally, an indication that more electromagnetic energy is present (e.g. more light is visible/more electromagnetic waves are being detected) may indicate more plasma generation. The controller 40 may be configured to determine that plasma generation is within a selected range in the event that the amount of turbulence and/or electromagnetic energy/emissions is within a selected range.

[0075] The amount of plasma generation may be determined based on an obtained indication of current and/or voltage at one of the electrodes. For example, the controller 40 may obtain an indication of a voltage being applied to the first electrode 111, and an indication of a resulting current passing through the first electrode 111 (e.g. using the first electrode sensor 43). The controller 40 may be configured to monitor voltage and current data over time and to determine based on this voltage and current data when a satisfactory plasma is generated. For example, the controller 40 may control the power supply 30 to increase the voltage applied to first electrode 111 over time, and the control may monitor the resulting current. As the voltage increases, the current will also increase initially before holding relatively stable as the voltage continues to increase. Once a threshold voltage is reached, the current will begin to increase, and the rate of increase in current will increase with increased voltage. The controller 40 may be configured to detect that satisfactory plasma generation has occurred in the region where the current starts increasing again. For example, the controller 40 may be configured to determine satisfactory plasma generation has occurred once the current begins to rise again. The controller 40 may then control the power supply 30 to no longer raise the voltage applied to the first electrode 111.

[0076] The amount of plasma generation may be determined based on an indication of chatter being provided to the power supply 30 in response to applying a voltage to the first electrode 111. For example, this may provide an indication of plasma generation occurring in the fuel, e.g. as vibrations occur due to plasma generation. The controller 40 may be configured to determine that plasma generation is within a selected range in the event that detected chatter is within a selected range.

[0077] The above examples describe operational parameters of the cell 100 which the controller 40 may be configured to determine and/or receive signals indicative thereof. Based on obtaining an indication of any of these operational parameters, the controller 40 may be configured to control operation of the heating system 50. In the event that the obtained indication is outside a selected range (e.g. above an upper threshold value and/or below a lower threshold value), the controller 40 may control operation of the system 50 so that a value for that parameter is within the selected range. For this, the controller 40 may control the liquid supplied to the cell 100 and/or the electrical energy applied to the fluid within the cell 100.

[0078] The controller 40 may be configured to control the liquid supplied to the cell 100 so that the at least one operational parameter is within a selected range. Controlling the liquid supply may comprise at least one of: (i) controlling a temperature of liquid supplied to the internal portion 125 of the cell 100, (ii) controlling a pressure of liquid supplied to the internal portion 125 of the cell 100, and/or (iii) controlling an amount of liquid supplied to the internal portion 125 of the cell 100 within a selected time window. The controller 40 may be configured to control operation of the heater 16 and/or the pump 18 to control the temperature and/or pressure of the liquid supplied to the cell 100. The fluid inlet 12 may comprise one aperture for receiving liquid, or it may comprise a plurality, e.g. to provide a plurality of entry points for liquid to flow into the cell. The controller 40 may be configured to control operation of the pump 18 to control the flow rate of fluid through the cell 100, e.g. to control how much fluid is delivered to the cell 100 per unit time. The liquid supply system 10 may be configured to provide a continuous flow of liquid to the cell 100, and the controller 40 may control the rate at which liquid is supplied to the cell 100.

[0079] In the event that the operational parameter indicates that increased output is needed from the cell (e.g. that the cell 100 needs to provide more heating of fluid), the controller 40 may control the liquid supply system 10 to provide at least one of: (i) liquid to the cell 100 at a higher temperature, (ii) liquid to the cell 100 under higher pressure, and/or (iii) more liquid to the cell 100. For example, if the operational parameter indicates that plasma generation is below a threshold, the control may increase the heat and/or pressure provided to the cell 100.

[0080] The controller 40 may be configured to control the electrical energy applied to electrodes of the cell 100 so that the at least one operational parameter is within the selected range. This may comprise at least one of: (i) controlling the amount of time for which a voltage is applied to the first electrode 111, (ii) controlling the voltage applied to the first electrode 111, (iii) controlling the voltage applied to the second electrode 112, and/or (iv) controlling the voltage applied to the heater. Where the operational parameter indicates that temperature generation needs to increase and/or plasma generation is below a threshold, the controller 40 may control the power supply 30 to increase the energy applied. For example, if plasma and/or heat generation is below a threshold value, the controller 40 may apply a voltage (or apply a larger voltage) to the heater and/or the first electrode 111.

[0081] The controller 40 may be configured to control both the electrical energy to be applied by the electrodes of the cell 100 and the liquid supply to the cell 100 (e.g. the two may be controlled simultaneously). The controller 40 may control one in dependence on how it is controlling the other. For example, the controller 40 may select how to control the electrical energy to be applied by the electrodes of the cell 100 based on how it will control the liquid supply to the cell 100 (and/or vice-versa). In the event that the controller 40 determines that increased plasma generation is required, the controller 40 may increase the voltage applied to the heater and/or first electrode 111, as well as increasing the temperature and/or pressure of water to be provided to the cell 100. In the event that the controller 40 determines that increased production of heated fluid is required, the controller 40 may increase the voltages applied to the electrodes and/or heater, as well as to increase the amount of liquid supplied to the cell 100.

[0082] In the second and third examples, the controller 40 is configured to receive a demand signal indicative of a demand on the output from the cell 100. The demand signal may indicate that more or less output is required from the cell 100. For example, this demand may be independent of the efficiency of cell 100 - the cell 100 may be operating within a threshold range for a relevant operational parameter, but the demand signal may indicate that the output needs to change (e.g. increase or decrease).

[0083] In the event that the demand signal indicates less output is required, the controller 40 is configured to control the liquid supplied to the cell 100 and the electrical energy applied to the electrodes of the cell 100. As the demand decreases, the controller 40 will decrease the supply of liquid to the cell 100. For example, the controller 40 may decrease the fluid flow rate through the cell 100. The liquid may still be supplied to the cell 100 at the same, or similar, temperature and/or pressure. The controller 40 may reduce the electrical energy to be applied. For example, the controller 40 may decrease the voltage applied to the first electrode 111. The controller 40 may still supply the same, or similar, voltage to the third electrode 113 and/or heater. The controller 40 may still control operation, e.g. as described above, so that plasma generation is within a selected range despite the total output being decreased.

[0084] In the event that the demand signal indicates more output is required, the controller 40 may control operation in the opposite way. The controller 40 may increase the rate that liquid is supplied to the cell 100 and the amount of electrical energy applied to the electrodes of the cell 100. The controller 40 may be configured to control operation of the cell 100 to avoid a flow rate of liquid through the cell 100 exceeding a plasma-generation threshold amount at which the flow rate is too high for sufficient plasma generation to occur. The controller 40 may still control operation, e.g. as described above, so that plasma generation is within a selected range despite the total output being increased.

[0085] In the fourth example, the controller 40 is configured to control operation of the system 50 in a start-up mode. For example, when the cell 100 is first turned on, it may take some time before it can be operated at higher efficiencies. In particular, the housing 120 of the cell 100 may be colder than it would during use. The controller 40 may be configured to determine that start-up operating conditions are to be used. For example, the controller 40 may obtain an indication of temperature for relevant components of the system 50 (e.g. the housing 120) to determine if the system 50 should operate in a start-up mode, and/or the controller 40 may determine based on an indication of previous use (e.g. that the system 50 has not been used recently) that start-up mode is to be used.

[0086] In start-up mode, the controller 40 is configured to control operation of the cell 100 to provide additional heating. The controller 40 may increase the voltage applied to the first electrode 111 to provide additional resistive heating. Additionally, or alternatively, the controller 40 may apply a voltage to the heater e.g. to provide resistive heating. For example, the controller 40 may control operation so that a greater voltage is applied to the heater when in the start-up mode than during normal operation (e.g. no voltage may be applied to the heater during normal operation). For example, the controller 40 may be configured to control operation of the heater to provide more heating during start-up (e.g. more heating energy may be used). The controller 40 may also control operation of an additional heater, such as a cartridge heater, to provide heating of the cell 100/internal portion 125. The controller 40 may control the supply of liquid to the cell 100 so that liquid supplied to the cell 100 is at a higher temperature and/or pressure and/or the flow rate of fluid through the cell 100 is lower when in start-up mode. The controller 40 may control the electrical energy applied to the electrodes and/or heater to be higher when in start-up mode.

[0087] The controller 40 may be configured to monitor at least one operational parameter of the cell 100 to determine when to leave start-up mode. For example, while an obtained indication of a temperature associated with the cell 100 remains below a threshold temperature value, the controller 40 may control operation of the system 50 to be in start-up mode. Once this temperature exceeds the threshold temperature value, the controller 40 may control operation of the system 50 to operate in normal-mode operating conditions. For example, less pre-heating of liquid may occur when in the normal-mode. The controller 40 may be configured to determine that sufficient plasma generation is occurring (e.g. in the manner described above), and in response to this, switch to the normal-mode of operation.

[0088] Another exemplary cell 100 will now be described with reference to Fig. 3. The cell 100 of Fig. 3 corresponds closely to that previously described, and so description of relevant components will not be repeated.

[0089] Fig. 3 shows a cell 100. The cell 100 includes a first electrode 111, a second electrode 112, a third electrode 113 and a resistive element 115. The cell 100 also includes a housing 120 which defines an internal portion 125, and which has a fluid inlet 12 and a fluid outlet 22. The cell 100 also includes a first end cap 122, a second end cap 124 and a compression device 126. The cell 100 may comprise a plasma cell (e.g. a plasma-generating fuel cell).

[0090] The internal portion 125 extends from a first end of the housing 120, which includes the fluid inlet 12, to a second end of the housing 120, which includes the fluid outlet 22. The internal portion 125 may be cylindrical. The housing 120 encapsulates the internal portion 125 apart from defining the fluid inlet 12 and the fluid outlet 22. In this example, the resistive element 115 lies adjacent to the internal wall of the housing 120 although in other examples, the resistive element 115 may be integral with the internal wall or separate from the wall and inside the internal portion 125. The first end cap 122 and second end cap 124 may also form part of the resistive element 115 - e.g. they also provide increased resistance to a conductive path from anode to cathode. The second electrode 112 is arranged within (e.g. integral with) the internal wall of the housing 120. The first and third electrode 113s are disposed at least partially within the internal portion 125. The first electrode 111 extends from outside the first end and into the internal portion 125. The third electrode 113 extends from outside the second end and into the internal portion 125. There is a gap between the two in the internal portion 125. The three electrodes and the resistive element 115 may be coaxial (e.g. they may be concentric).

[0091] The first end cap 122 encloses the internal portion 125 at the first end. The second end cap 124 encloses the internal portion 125 at the second end. The end caps 122, 124 form part of the housing 120 for the internal portion 125. The first end cap 122 is non-conducting. The second end cap 124 is non-conducting. Each end cap may effectively form part of a resistive barrier for a conductive path from the anode to the cathode (e.g. the end caps may form part of, or work in combination with, the resistive element 115). Each end cap 122, 124 includes one or more apertures to enable flow of fluid therethrough. One or both end caps may have an aperture near to its centre. For example, the aperture(s) in the first end cap 122 may be located proximal to the first electrode 111. The aperture(s) may be arranged to facilitate flow of liquid into the internal portion 125 while inhibiting the likelihood of a conductive path forming from the anode to the cathode through said aperture(s). The first end cap 122 may have a plurality of apertures to facilitate multiple different points through which liquid may flow into the internal portion 125. The compression device 126 is located within the first end of the housing 120 adjacent to the first end cap 122. The compression device 126 may comprise any suitable biasing means, such as a spring. Each end of the housing 120 may have thicker material, as shown in Fig. 3. At least one portion of the housing 120 may be connected to electrical ground. As shown in Fig. 3, the first end of the housing 120 is grounded. One or both of the end caps may include a heating element (e.g. a resistive heater), which may be used to provide heating to liquid within the internal portion 125 (e.g. during start-up). For example, the power supply 30 may couple to a heater in the end cap (e.g. in the first end cap 122). The controller 40 may be configured to control application of power to the heater in the end cap to provide heating.

[0092] The first electrode 111 may include a conductor extending along the length of the electrode. The conductor may be provided within an insulating body to provide the electrode. An insulating shroud may be provided for at least some of the region of the electrode within the internal portion 125 (e.g. the insulating shroud may be provided at the end of the first electrode 111 which is disposed in the internal portion 125). For example, the electrode may have a conductor extending along a central axis, where that conductor is radially surrounded by an insulator along the length of the conductor being in the internal portion 125 (e.g. it may be along the entire length). The first electrode 111 may also include a carrier at its end away from the internal portion 125. The carrier may comprise suitable fixing means, such as a ledge, for attachment to the first end cap 122. The carrier may comprise a sealing means and attachment means for attaching the first electrode 111 to the first end cap 122 and sealing the internal portion 125. For example, a radially extending flange may provide a sealing face. For example, a screw thread may enable the end cap 122 to be secured to the electrode to seal the internal portion 125. A similar arrangement may be provided for the third electrode 113, and e.g. its arrangement with the second end cap 124.

[0093] The compression device 126 is configured to apply pressure on the first end cap 122 towards the internal portion 125 of the housing 120. The compression device 126 may facilitate retaining the internal portion 125 of the housing 120 under pressure. The housing 120 is arranged to enable the flow of liquid into the internal portion 125 through the fluid inlet 12 and a flow of steam/liquid out through the fluid outlet 22. The housing 120 is arranged to provide structural support to enable the internal portion 125 to be held under pressure with fluid therein. For example, the side wall(s) of the housing 120 is arranged to withstand radial expansion of the internal portion 125, and the end walls of the housing 120 are arranged to withstand longitudinal expansion of the internal portion 125. Operation of the cell 100 is similar to that described above with reference to Figs. 1 and 2, and so shall not be described again here.

[0094] Heating systems described herein may find use in larger generation systems. Examples of such larger generating systems will now be described with reference to Figs. 4 and 5.

[0095] Fig. 4 shows a heat and power generating system 1000. The heat and power generating system 1000 comprises a power management system 200, a cell 100, a heat management system 300, a fluid management system 400, and a power generation system 500. Also shown in Fig. 4 is a mains coupling 220. The cell 100 may comprise a plasma cell (e.g. a plasma-generating fuel cell).

[0096] Fig. 4 shows a block diagram to illustrate the functional interrelationship between the different component systems of the heat and power generating system 1000. However, it is to be appreciated that this is intended to demonstrate the functional connections, rather than specific structural connections. It will be appreciated that the structural arrangement of the different component systems may be interlinked (e.g. as will be described later with reference to Fig. 5).

[0097] As shown in Fig. 4, the power management system 200 is coupled to the cell 100. The cell 100 is coupled to the heat management system 300. The heat management system 300 is coupled to each of the power generation system 500 and the fluid management system 400. The fluid management system 400 is coupled to the cell 100. The power generation system 500 is coupled to the power management system 200. This coupling is intended to demonstrate the functional interrelationships between the different component systems. The power management system 200 may also be coupled to the mains coupling 220 (e.g. as shown in Fig. 4).

[0098] The power management system 200 is configured to control the application of power to the cell 100. The power management system 200 may control the electrical energy (e.g. voltage) applied to the first electrode 111 of the cell 100. The power management system 200 may also control the electrical energy (e.g. voltage) applied to the remaining electrodes and/or the heater of the cell 100. The power management system 200 may also control operation of any pump 18 and/or heater 16 for providing liquid to the cell 100 under pressure and/or at a higher temperature. The power management system 200 may therefore control the operation of the cell 100 to generate heated fluid.

[0099] The cell 100 is configured to operate as described above (e.g. to apply electrical energy inside its internal portion 125 to generate heated fluid).

[0100] The heat management system 300 is configured to receive the heated fluid generated by the cell 100. The heat management system 300 is configured to utilise this heated fluid to provide relevant thermal work. For example, the heat management system 300 may be configured to provide heating using this heated fluid, e.g. for heating buildings etc. The heat management system 300 may comprise one or more components for providing heat transfer from the heated fluid from the cell 100 to another component and/or substance. For example, the heat management system 300 may comprise one or more heat exchangers.

[0101] The power generation system 500 is configured to receive the heated fluid generated by the cell 100. The power generation system 500 is configured to utilise this heated fluid to generate power (e.g. electrical energy). Fig. 4 shows the output of the cell 100 being provided to the heat management system 300, and from the heat management system 300 to the power generation system 500. However, it will be appreciated in the context of the present disclosure that one of these systems may not be included, or the two systems may be provided by the same components. The power generation system 500 may comprise one or more generators to generate electricity based on movement of the heated fluid (e.g. using pressurised gas to drive a turbine to generate electricity). This arrangement may also include some heat management (e.g. to distribute heat to other parts of the power generation system 500. In some examples, the heated fluid may be used for heating purposes and for power generation purposes. The heat management system 300 may then control distribution of the heated fluid accordingly (e.g. to control distribution of heated fluid to the power generation system 500). For example, the work extraction system 20 described above may comprise such a heat management system 300 and/or power generation system 500.

[0102] Power generated by the power generation system 500 may then be supplied to the power management system 200. For example, this power generated by the power generation system 500 may in turn be used by the power management system 200 to power the cell 100 to provide further power generation. The power management system 200 may also be coupled to the mains coupling 220 to receive and/or transmit power to the mains. For example, during start-up mode, the power management system 200 may obtain all of its power from the mains, but after start-up, at least some of its power may be received from the power generation system 500. After start-up, some of the power generated by the power generation system 500 may be provided to the mains coupling 220 for distribution elsewhere.

[0103] The fluid management system 400 is configured to provide liquid to the cell 100 (e.g. as described above for the liquid supply system 10). The fluid management system 400 is configured to receive fluid which has been output from the cell 100. The fluid management system 400 may be configured to process fluid which was heated by the cell 100, and which has since been used by the heat management and/or power generation systems. The heated fluid generated by the cell 100 may be at high temperature and/or pressure. The heat management and/or power generation systems are configured to extract useable work from this high temperature/pressure fluid. Once the useable work has been extracted, the fluid may be at much lower temperatures and pressures. For example, it may leave the cell 100 as high temperature and pressure gas, and once fully used for work extraction it may be liquid again (e.g. at a lower temperature). The fluid management system 400 is configured to process this used fluid. Processing the used fluid may comprise returning it to the environment and/or processing (e.g. filtering) the fluid, e.g. so that it could be used again as a liquid to be provided to the cell 100.

[0104] In operation, the power management system 200 receives power (e.g. from the mains coupling 220 and/or the power generation system 500). The power management system 200 applies electrical energy to the cell 100 (e.g. to the first electrode 111). The fluid management system 400 supplies liquid to the cell 100. The electrical energy applied to the cell 100 in turn heats to the liquid provided to the cell 100 so that the cell 100 outputs a heated fluid. This heated fluid is received by the heat management system 300 and/or power management system 200, which extract useable work (e.g. for heating and/or power generation) from the heated fluid. Once this work has been extracted, any power generated by the power generation system 500 is provided to the power management system 200. The used fluid is provided to the fluid management, which processes this used fluid. This process may be repeated, e.g. continually, to provide heat and/or power generation.

[0105] A more specific example of a heat and power generating system 1000 will now be described with reference to Fig. 5.

[0106] Fig. 5 shows a heat and power generating system 1000. The heat and power generating system 1000 comprises a cell 100. Also included is a power supply 30, a pump 18, and a drain 15. The system 1000 includes a plurality of heat exchangers, which, as shown in Fig. 5 includes a first heat exchanger 301, a second heat exchanger 302, a third heat exchanger 303 and a fourth heat exchanger 304. The system 1000 further includes a heat engine 510 having a first driving region 511 and a second driving region 512, and a generator 520. The cell 100 may comprise a plasma cell (e.g. a plasma-generating fuel cell).

[0107] The cell 100 is connected to receive two inputs (liquid and electricity) and to provide an output (heated fluid). The inputs to the cell 100 are shown at the bottom and right of the cell 100, and the output is at the top.

[0108] The output of the cell 100 is coupled to each of the first heat exchanger 301 and the heat engine 510. A flow path for the output may split into two, with one path coupling to the first heat exchanger 301 and another path coupling to the heat engine 510. In particular, the output from the cell 100 is coupled to the first driving region 511 of the heat engine 510. The heat engine 510 has a first engine inlet for receiving fluid to drive the engine 510 in the first driving region 511. The first driving region 511 is also coupled to a first engine outlet for outputting the fluid which has driven the engine 510 in the first driving region 511. The first engine outlet is also coupled to the first heat exchanger 301.

[0109] The engine 510 also includes a second engine inlet and a second engine outlet. The second engine inlet is for receiving fluid to drive the engine 510 in the second driving region 512. The second engine outlet is for outputting the fluid which has driven the engine 510 in the second driving region 512. The second engine inlet is also coupled to the first heat exchanger 301. For example, fluid may flow from the first engine outlet to the second engine inlet through the first heat exchanger 301. The engine 510 is coupled to a generator. Each of the first and second driving regions 511, 512 of the engine 510 may couple to the generator. The first and second driving regions 511, 512 may drive the engine 510 at a different ratio. Both may contribute to driving the generator, and thus generating electricity.

[0110] The first heat exchanger 301 may be coupled to the second heat exchanger 302. The system 1000 may be configured for heated fluid from the cell 100 to flow through the first heat exchanger 301 and onto the second heat exchanger 302. The second heat exchanger 302 may also be coupled to the third and/or fourth heat exchangers 303, 304.

[0111] The power supply 30 is coupled to the cell 100. The power supply 30 provides an input to the fuel supply (e.g. to provide electrical energy to the electrodes of the cell 100). The power supply 30 may include a coupling for receiving power from the mains (e.g. the power supply 30 may receive three phase power). The power supply 30 may include a converter (e.g. AC to DC) for providing DC output, such as a high voltage DC output. The high voltage DC output may then be supplied to the cell 100, e.g. to be applied to the first electrode 111. The power supply 30 may also be coupled to the generator to receive generated electricity therefrom. The power supply 30 may receive AC or DC from the generator. Where AC is received, this may be converted to DC (e.g. using the same or a different AC to DC converter). Some of the electricity generated by the generator may be provided to the mains, e.g. for use elsewhere.

[0112] The third heat exchanger 303 and/or the pump 18 may couple to the input for the cell 100. Liquid to be supplied to the cell 100 may be heated and/or pressurised using the third heat exchanger 303 and/or the pump 18. This may provide the liquid input to the cell 100 which is used for generating heated fluid. The heated fluid output from the cell 100 is ultimately coupled to a drain 15. For example, the fluid which has passed through both regions 511, 512 of the engine 510 may be provided to the drain 15. Likewise, fluid which has passed through any of the heat exchangers (e.g. the second, third and/or fourth heat exchanger 302, 303, 304) may then be coupled to the drain 15.

[0113] The system 1000 is arranged to provide multiple uses for the heated fluid generated by the cell 100, e.g. to extract work from the heated fluid in multiple ways. The system 1000 is configured to provide high temperature, high pressure fluid output from the cell 100 to drive the first driving region 511 of the engine 510. The generator is configured to generate electricity from this driving of the first driving region 511. The first heat exchanger 301 is configured to reheat this fluid which has driven the first driving region 511 of the engine 510. The first heat exchanger 301 is arranged to exchange heat between the heated fluid from the cell 100 and the fluid which has driven the first driving region 511 of the engine 510. The system 1000 is configured to use the re-heated fluid which has driven the first driving region 511 of the engine 510 to drive the second driving region 512 of the engine 510. The second driving region 512 of the engine 510 is configured to have an easier ratio (e.g. so that less energy is required to drive a rotation) as compared to the first driving region 511. The fluid passing through the second driving region 512 may be at a lower pressure than the first driving region 511. The generator is configured to generate electricity in response to driving of the first and/or second driving regions 511, 512 of the engine 510.

[0114] The system 1000 is arranged for heated fluid which has passed through the first heat exchanger 301 and/or out the second engine outlet to provide further heating use, where relevant. For example, the system 1000 may be arranged to deliver the heated fluid to one or more of the second, third and/or fourth heat exchangers 302, 303, 304 for extracting useable heating work from this heated fluid. Any of these heat exchangers 302, 303, 304 may couple to an external component for using such heat. The system 1000 may be configured to exchange heat from the heated fluid with the liquid to be supplied to the cell 100 to provide heating thereof prior to being delivered to the cell 100. The system 1000 is arranged to discard any remaining fluid using the drain 15.

[0115] In operation, liquid is supplied to the cell 100, and electrical energy is applied to the electrodes of the cell 100 to generate a heated fluid. The heated fluid leaves the cell 100 and flows to both the first heat exchanger 301 and the first driving region 511 of the engine 510. The heated fluid flows through the first driving region 511 to drive the engine 510 and generator to generate electricity. This fluid then flows into the first heat exchanger 301 where it is re-heated by the heated fluid which travelled directly (e.g. not via the engine 510) to the first heat exchanger 301 from the cell 100. The fluid that has travelled through the engine 510 is then reheated before flowing through the second engine driving region. This fluid then drives the engine 510 and generator to generate electricity. Fluid which has passed through the second driving region 512 of the engine 510 and/or through the first heat exchanger 301 away from the engine 510 is then used in further heat exchangers 302, 303, 304 to extract more useable heat work from the fluid. This fluid is then discarded using the drain 15.

[0116] It will be appreciated in the context of the present disclosure that the examples described herein are not intended to be considered limiting. Alternative and/or additional features may also be included. For example, reference has been made to concentric electrodes, e.g. which are arranged coaxially with a central first electrode 111 and a second electrode 112 located radially outward form the first electrode 111. However, this arrangement may be reversed. Alternatively, the electrodes need not be arranged concentrically. For example, the two electrodes could be arranged in an alternative fashion, such as being arranged as plate electrodes, e.g. two parallel plates, or as parallel wires or other parallel objections such as spheres.

[0117] Reference has been made herein to electrodes of the cell 100. The first electrode 111 may provide an anode, the second electrode 112 a cathode, and/or the third electrode 113 a balancing electrode. It is to be appreciated in the context of the present disclosure that each electrode may provide a conductive path, e.g. each electrode may comprise a conductor extending along a length of the electrode. The anode may comprise a conductor which provides a conductive path from external to the internal portion 125 into the internal portion 125 to the distal end of the conductor within the internal portion 125. The cathode may comprise a conductor which provides a conductive path from in, or adjacent to, the internal portion 125 to away from the internal portion 125. The balancing electrode may comprise a conductor which provides a conductive path into the internal portion 125 from external to the internal portion 125 or away from the internal portion 125 from within the internal portion 125. The first electrode 111 may be arranged to pass closer to the third electrode 113 than it does to the second electrode 112, e.g. the minimum distance between a point on the first electrode 111 and a point on the third electrode 113 may be less than that for the first and second electrode 112. For example, the minimum distance between first and third electrodes may be much less than that for the first and second electrodes 111, 112.

[0118] Examples described herein relate to use of one cell. However, it is to be appreciated in the context of the present disclosure that multiple cells may be provided. For example, operation of the different cells may be timed to provide a consistent output of heated fluid over time. Operational timing of each cell may be offset so that the total output of heated fluid over time remains relatively constant. For example, it is to be appreciated that each cell may have an output of heated fluid which varies over time, and the multiple cells may have their operations timed so that the output from all of the cells combined is more consistent than for the output of any one cell on its own. The controller 40 may be configured to control the supply of liquid to each cell, and/or the application of electrical energy to the electrodes to provide consistent output of heated fluid. For example, one or more sensors may be used for each cell to determine operational parameters thereof, such as its output of heated fluid.

[0119] It is to be appreciated that the supply of liquid to the cell 100 may happen continuously over time or only in discrete time periods. The controller 40 may be configured to control whether or not liquid is delivered to the cell 100. For example, the cell 100 may comprise a fluid inlet valve operable to control whether fluid can flow into the internal portion 125 or not, and/or operation of the pump 18 may be controlled to either deliver liquid to the cell 100 or not. There may be a continuous turnover of fluid within the cell 100, e.g. fluid is continually being provided to the cell 100 and heated fluid is continuously leaving the cell 100 (e.g. as a gas through the fluid outlet 22). There may be discrete time periods for fluid input so that one unit of liquid is delivered to the cell 100 (e.g. enough to fill the cell 100), then no further liquid is provided while electrical energy is applied to the electrodes to provide heated fluid, e.g. once all the fluid has been heated sufficiently for release through the fluid outlet 22. Then, another unit of liquid may be provided to the cell 100. It is to be appreciated that for this mode of operation, multiple different cells being operated together may comprise timing operation so that while unit is being delivered to one cell, another cell is applying electrical energy to the fluid in its cell. It will be appreciated that multiple different cells (e.g. more than 2) may be used with timings all offset from each other, e.g. so that when one is nearly finishing heating, another is mid-heating, and another is just starting heating etc.

[0120] The internal surface of the housing 120 has been described as being an electromagnetic energy-absorbing surface. This may be a property of the material used to provide the housing 120, e.g. steel, and/or a coating may be provided on the internal surface to facilitate absorption of electromagnetic energy (e.g. from photon emissions). It is to be appreciated that absorbing electromagnetic energy may comprise receiving incident photons (e.g. in the visible light spectrum) and in response to said photons being incident on the surface, generating heat. It will also be appreciated that electrons or other particles (e.g. charged particles emitted from the plasma/plasma-cooling process) may also be incident on the internal surface of the housing 120. The internal surface of the housing 120 may also be configured to generate heat in response to such incident particles. For example, resistive heating may be provided in response to electron flow through the internal surface.

[0121] It will be appreciated from the discussion above that the examples shown in the figures are merely exemplary, and include features which may be generalised, removed or replaced as described herein and as set out in the claims. With reference to the drawings in general, it will be appreciated that schematic functional block diagrams are used to indicate functionality of systems and apparatus described herein. In addition the processing functionality may also be provided by devices which are supported by an electronic device. It will be appreciated however that the functionality need not be divided in this way, and should not be taken to imply any particular structure of hardware other than that described and claimed below. The function of one or more of the elements shown in the drawings may be further subdivided, and/or distributed throughout apparatus of the disclosure. In some examples the function of one or more elements shown in the drawings may be integrated into a single functional unit.

[0122] As will be appreciated by the skilled reader in the context of the present disclosure, each of the examples described herein may be implemented in a variety of different ways. Any feature of any aspects of the disclosure may be combined with any of the other aspects of the disclosure. For example method aspects may be combined with apparatus aspects, and features described with reference to the operation of particular elements of apparatus may be provided in methods which do not use those particular types of apparatus. In addition, each of the features of each of the examples is intended to be separable from the features which it is described in combination with, unless it is expressly stated that some other feature is essential to its operation. Each of these separable features may of course be combined with any of the other features of the examples in which it is described, or with any of the other features or combination of features of any of the other examples described herein. Furthermore, equivalents and modifications not described above may also be employed without departing from the invention.

[0123] Certain features of the methods described herein may be implemented in hardware, and one or more functions of the apparatus may be implemented in method steps. It will also be appreciated in the context of the present disclosure that the methods described herein need not be performed in the order in which they are described, nor necessarily in the order in which they are depicted in the drawings. Accordingly, aspects of the disclosure which are described with reference to products or apparatus are also intended to be implemented as methods and vice versa. The methods described herein may be implemented in computer programs, or in hardware or in any combination thereof. Computer programs include software, middleware, firmware, and any combination thereof. Such programs may be provided as signals or network messages and may be recorded on computer readable media such as tangible computer readable media which may store the computer programs in non-transitory form. Hardware includes computers, handheld devices, programmable processors, general purpose processors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and arrays of logic gates. For example, any controller 40 described herein may be provided by any control apparatus such as a general purpose processor configured with a computer program product configured to program the processor to operate according to any one of the methods described herein. The functionality of the controller 40 may be provided by an application specific integrated circuit, ASIC, or by a field programmable gate array, FPGA, or by a configuration of logic gates, or by any other control apparatus.

[0124] Other examples and variations of the disclosure will be apparent to the skilled addressee in the context of the present disclosure.

[0125] The present disclosure also includes the following numbered clauses:

1. A heating system comprising:

a liquid supply system;

a cell configured to: receive liquid from the liquid supply system, provide heating thereof, and output heated fluid;

a work extraction system configured to extract useable work from heated fluid output from the cell;

wherein the cell comprises: (i) a housing arranged to define an internal portion for receiving liquid to be heated, and (ii) a plurality of electrodes configured to apply electrical energy to fluid in the internal portion; and

wherein the electrodes are configured to apply electrical energy to said fluid in the internal portion to generate one or more bubbles of plasma for releasing energy into said fluid in the internal portion and the housing to provide heating of the fluid in the internal portion.

2. The heating system of clause 1, wherein the system further comprises a controller configured to: (i) receive a signal indicative of at least one operational parameter of the cell, and (ii) control operation of the heating system based on said operational parameter.

3. The heating system of clause 2, wherein the controller is configured to control operation of the heating system so that heat and/or plasma generation in the cell is above a threshold level.

4. The heating system of any of clauses 2 to 3, wherein controlling operation of the heating system comprises controlling at least one of: (i) the supply of liquid to the cell by the liquid supply system, and (ii) the electrical energy applied by the electrodes.

5. The heating system of clause 4, wherein the controller is configured to control the supply of liquid to the cell and/or the electrical energy applied by the electrodes based on an obtained indication of demand for heating to be provided by the cell.

6. The heating system of clause 5, wherein in the event that the obtained indication of demand indicates increased demand for heating to be provided by the cell, the controller is configured to increase at least one of: (i) the temperature of liquid supplied to cell, (ii) the pressure of liquid supplied to the cell, (iii) the amount of liquid supplied to the cell, and (iv) the amount of electrical energy applied by the electrodes.

7. The heating system of any of clauses 2 to 6, wherein the signal indicative of at least one operational parameter comprises an indication of a quality and/or quantity of plasma generation within the cell; and
wherein the controller is configured to control operation of the heating system so that the quality and/or quantity of plasma generation remains within a selected range.

8. The heating system of clause 7, wherein the signal indicative of a quality and/or quantity of plasma generation comprises an indication of at least one of: (i) a pressure and/or temperature of fluid output from the cell, (ii) an amount and/or type of electromagnetic energy present within the cell, (iii) chatter associated with supply of power to one or more of the electrodes, (iv) a current flow and/or voltage associated with one or more of the electrodes, and (v) fluid flow dynamics within the cell.

9. The heating system of any of clauses 2 to 8, wherein the controller is configured to control at least one of: (i) the supply of liquid to the cell based on the electrical energy to be applied by the plurality of electrodes, and (ii) the electrical energy to be applied by the plurality of electrodes based on the supply of liquid to the cell.

10. The heating system of any of clauses 2 to 9, wherein the signal indicative of at least one operational parameter comprises an indication of a temperature associated with at least one of: the cell, the fluid in the cell, and the fluid output from the cell; and
wherein the controller is configured to control at least one of: (i) the electrical energy applied by the electrodes, (ii) the supply of liquid to the cell, and (iii) an external heater, to increase the temperature of the cell, the fluid in the cell, and/or the fluid output from the cell in the event that the indication of temperature is below a threshold level.

11. The heating system of clause 10, wherein the controller is configured to increase the electrical energy applied by the electrodes to provide increased heating and/or decrease the flow rate of liquid through the cell in the event that the indication of temperature is below the threshold level.

12. The heating system of any preceding clause, wherein an internal surface of the housing of the cell comprises an electromagnetic energy-absorbing material arranged to convert incident photons into heat.

13. The heating system of any preceding clause, wherein the liquid supply system is configured to supply liquid to the cell under pressure, and the cell is arranged to retain fluid in the housing under pressure.

14. The heating system of any preceding clause, wherein the liquid supply system is configured to increase heating of liquid prior to supplying it to the cell in the event that heat and/or plasma generation of the cell is below a threshold level.

15. The heating system of any preceding clause, wherein the plurality of electrodes comprises: (i) an anode arranged to provide a conductive path for current to be applied to fluid in the internal portion, and (ii) a cathode arranged to provide a conductive path away from the internal portion for current received from the anode through the fluid in the internal portion.

16. The heating system of clause 15 further comprising a balancing electrode arranged to provide an additional conductive path towards or away from fluid in the internal portion, for example wherein the anode, cathode and balancing electrode all have the same coefficient of thermal expansion.

17. The heating system of clause 16, wherein the balancing electrode is separated from the conductive path from the first electrode to the second electrode, for example wherein the balancing electrode extends perpendicularly away from the conductive path from the first electrode to the second electrode, for example wherein the balancing electrode is arranged to be closer to the first electrode than the second electrode is.

18. The heating system of any of clauses 15 to 17, wherein the cell comprises a resistive element arranged between the anode and cathode, for example wherein the resistive element comprises quartz.

19. The heating system of any of clauses 15 to 18, wherein the anode and cathode are arranged concentrically with each other.

20. The heating system of any preceding clause, wherein the system further comprises a heater coupled to, or part of, the cell, and wherein the system is configured to increase electrical energy applied to the heater to increase the temperature associated with at least one of: the cell, fluid inside the cell, and fluid output from the cell.

21. The heating system of any preceding clause, wherein the work extraction system comprises at least one of: (i) a regulator for mass transfer of hot and/or pressurised fluid, (ii) a heat exchanger for transfer of heat to a working fluid, and (iii) a power generation system such as a steam-based power generation system.

22. A system comprising:

a cell configured to heat liquid provided thereto, the cell comprising: an inlet for receiving a liquid to be heated, and an outlet for outputting heated fluid;

a power management system configured to control application of electrical energy to the cell to control the heating of fluid in the cell;

a work extraction system coupled to the outlet and configured to extract useable work from heated fluid output from the cell; and

a fluid management system coupled to the inlet of the cell, and configured to: (i) supply liquid to be heated to the cell, and (ii) process heated fluid which has been output by the cell and used by the work extraction system.

23. A method of providing a heated fluid for extracting useable work therefrom, the method comprising:

supplying a liquid to be heated to a cell, wherein the cell comprises: (i) a housing arranged to define an internal portion for receiving the liquid to be heated, and (ii) a plurality of electrodes configured to apply electrical energy to fluid in the internal portion;

controlling operation of the plurality of electrodes to apply electrical energy to fluid in the internal portion to generate one or more bubbles of plasma;

generating heat in the housing proximal to the internal portion in response to the housing receiving incident photons associated with plasma bubbles in the internal portion;

using the housing to conductively heat fluid in the internal portion.

24. A method of controlling operation of a heating system, the heating system comprising a cell comprising: (i) a housing arranged to define an internal portion for receiving liquid to be heated, and (ii) a plurality of electrodes configured to apply electrical energy to fluid in the internal portion, the method comprising:

controlling operation of the electrodes to apply electrical energy to fluid in the internal portion to generate one or more bubbles of plasma for releasing energy from the plasma into the fluid in the internal portion and the housing to provide heating of the fluid in the internal portion, wherein controlling operation of the electrodes comprises:

receiving a signal indicative of at least one operational parameter associated with the cell and/or a fluid associated therewith;

operating in a 'cold-start' mode when the operational parameter indicates heating and/or plasma generation is below a threshold level; and

operating in a 'normal' mode when the operational parameter indicates heating and/or plasma generation is above the threshold level;

wherein operating in the cold-start mode comprises controlling at least one of: (i) the electrical energy applied by the electrodes, (ii) supply of liquid to the cell, and (iii) operation of an external heater, to increase the temperature of the cell and/or the fluid associated therewith in the event that the operational parameter indicates heating and/or plasma generation is below a threshold level.

25. A computer program product comprising computer program instructions configured to control a processor to perform the method of clauses 23 or 24.

Claims

1. A plasma cell (100) comprising:

a housing (120) arranged to define an internal portion (125) for receiving liquid from a liquid supply system (10);

a plurality of electrodes comprising: a first electrode (111), a second electrode (112) and a third electrode (113); and

a resistive element (115);

wherein the first electrode (111) and third electrode (113) are at least partially disposed within the internal portion (125);

wherein the first electrode (111) is arranged to provide a conductive path for current to be applied to liquid in the internal portion (125);

wherein the second electrode (112) is arranged to provide a conductive path for carrying current away from the internal portion (125);

wherein the third electrode (113) is arranged away from a conductive path from the first electrode (111) to the second electrode (112);

wherein the resistive element (115) is provided in the internal portion (125) between the first electrode (111) and the second electrode (112) to increase the electrical resistance of the conductive path therebetween; and

wherein the first electrode (111) is configured to apply electrical energy to liquid in the internal portion (125) to generate one or more bubbles of plasma for releasing energy into said fluid in the internal portion (125) and the housing (120) to provide heating of the fluid in the internal portion (125).

2. The plasma cell (100) of claim 1, wherein the conductive path from the first electrode (111) to the second electrode (112) is radially outward from the first electrode (111).

3. The plasma cell (100) of any preceding claim, wherein the third electrode (113) is offset from the first electrode (111) along a longitudinal axis of the cell (100).

4. The plasma cell (100) of any preceding claim, wherein the third electrode (113) is arranged to provide a conductive path which runs perpendicular to the conductive path from first electrode (111) to second electrode (112).

5. The plasma cell (100) of any preceding claim, wherein the resistive element (115) is located radially outward from the first electrode (111) and not as far out as the second electrode (112).

6. The plasma cell (100) of any preceding claim, wherein the third electrode (113) is arranged to provide an additional conductive path towards or away from the internal portion (125).

7. The plasma cell (100) of any preceding claim, wherein the first electrode (111), the second electrode (112) and the third electrode (113) all have the same coefficient of thermal expansion.

8. The plasma cell (100) of any preceding claim, wherein the third electrode (113) extends perpendicularly away from the conductive path from the first electrode (111) to the second electrode (112).

9. The plasma cell (100) of any preceding claim, wherein the third electrode (113) is closer to the first electrode (111) than the second electrode (112) is.

10. The plasma cell (100) of any preceding claim, wherein the first electrode (111) and the second electrode (112) are arranged concentrically with each other.

11. The plasma cell (100) of any preceding claim, wherein the first electrode (111) and the third electrode (113) are parallel, optionally wherein the first electrode (111) and the second electrode (112) are coaxial.

12. The plasma cell (100) of any preceding claim, wherein the resistive element (115) comprises a sleeve inserted between the first electrode (111) and second electrode (112) within the internal portion (125), optionally wherein the sleeve sits adjacent to the housing (120).

13. The apparatus of any preceding claim, further comprising a controller (40) configured to reduce or stop applying a voltage to the first electrode (111) in the event that a change in current or a rate of change in current exceeds a threshold value.

14. The plasma cell (100) of any preceding claim, wherein the second electrode (112) is arranged capacitively with the first electrode (111).

15. The plasma cell (100) of claim 14, wherein the cell (100) is configured to apply electrical energy to the first electrode (111) to charge up the capacitor provided by the first and second electrodes (111; 112) to generate one or more bubbles of plasma in the fluid in the internal portion (125) for releasing energy into said fluid in the internal portion (125) and the housing (120) to provide heating of the fluid in the internal portion (125).

Drawing