WO2025158048A1

WO2025158048A1 - Improved eco-friendly boiler power generation

Info

Publication number: WO2025158048A1
Application number: PCT/EP2025/051877
Authority: WO
Inventors: Graham Arthur COOK; Joshua Samuel WAY
Original assignee: Individual
Current assignee: Individual
Priority date: 2024-01-25
Filing date: 2025-01-24
Publication date: 2025-07-31
Anticipated expiration: 2026-07-25
Also published as: WO2025158050A1; WO2025158049A1

Abstract

The present invention provides an eco-friendly boiler comprising a water tank, wherein a portion of the water tank comprises a spray chamber, one or more spray nozzles configured to spray water into the spray chamber of the water tank and one or more microwave generators coupled to the spray chamber and configured to emit microwaves towards the water emerging from the spray nozzle or nozzles and the source of microwaves is a solid-state microwave generator.

Description

Improved eco-friendly boiler power generation

The present invention relates to an improved configuration of an eco-friendly boiler so is to make most efficient generation of microwaves for the heating of water in a heating boiler, such as for use in hot water and central heating.

Background

The concept of using microwaves for the heating of water is well established, such as disclosed in CN107388217A, CN204388336U, and US4288674A disclose water heating apparatus wherein the water is heated by means of microwaves.

WO8801826A1 discloses a central heating boiler for use in domestic and office systems wherein what is heated by means of microwaves for distribution to space heating radiators.

Recent developments such as those disclosed in GB 2608875A to the same inventor has provided a more practical arrangement for microwave heating of water such as for use in hot water and central heating. However ongoing development has shown that there is room for optimisation of the basic system particularly with regards to the generation of microwaves. In particular, one of the advantages of microwave heating is that relatively low volumes of water can be heated and delivered for use, making the heating process more efficient by the reduction of water in the system and also the speed of heating. This can for example give advantages of plug flow of the hot water in the system giving more and more immediate indefinite delivery of hot water, such as for use in living accommodation. However, one of the limitations that need to be addressed is the efficient generation of microwaves of microwave energy not only for intrinsic efficiency but also because, for example in the United Kingdom, the electricity supply such as to domestic premises is limited to around 100 amps this gives a maximum theoretical power input to the boiler of around 24 kilowatts. This theoretical power is theoretical in as much as other demands will typically be placed on the electrical system and therefore practical limits are more realistically around 20 kilowatts. Whereas a typical range for the power output of a domestic boiler, typically gas-fired, is between 24 and 42 kilowatts (kW). There is therefore a need to boost the intensity of water heating using microwaves to optimise the use of what power is available.

Further, apparatus used for the domestic generation of microwaves typically utilises very high voltages this is intrinsically undesirable but typically when like, for example, a domestic microwave oven the power requirements are an order of magnitude higher and the potential for a fatal accident is proportionally greater. In particular, households are to be protected by a residual current device (RCD) limited to 30 milliamps however there is a further parameter of “sensitivity” which relates to the speed at which the current is disconnected. High sensitivity' RCDs, such as at rated 30mA or even 10mA, are designed to disconnect the supply within 40ms at 150mA and within 300ms at rated tripping current of 30mA to protect the user. As will be appreciated when the voltage required to operate a magnetron is in the order of 3000 to 4000 volts then the current that may pass even in a millisecond timescale is considerable and in the nature of a high power requirement boiler with a 10 kilowatt rather than 1 kw means that some degree of leakage current was be tolerated in normal operation. There is therefore a considerable need to mitigate the risk of electrocution in microwave boilers which is order of magnitude greater than from a simple domestic microwave oven even though the setting in which the apparatus is used is directly analogous.

The present invention

The present invention in its various aspects is as set out in the appended claims.

The present invention provides an eco-friendly boiler comprising, a water tank, wherein a portion of the water tank comprises a spray chamber, one or more spray nozzles configured to spray water into the spray chamber of the water tank and one or more microwave generators coupled to the spray chamber configured to emit microwaves towards the water emerging from the spray nozzle or nozzles, which represent known features, and the present invention further provides that the source of microwaves is a solid state microwave generator.

In the context of the claimed invention, a microwave generator refers to a device which converts electrical power to microwave power and serves to emit that microwave power in a directed manner via one or more emitters configured for emitting microwaves and thus these devices can intrinsically be considered as an emitter.

The use of a solid-state microwave generator whilst considered a possibility for food heating has not been considered for use in a boiler. The use of electrical microwave generators within a boiler also has additional safety issues to consider due to the higher energy outputs that are involved In particular, the use of an electrical microwave generator in close proximity to the water in the boiler could cause a potential hazard especially as a large amount of energy may be needed to produce enough microwaves to penetrate the water within the tank.

However, by replacing the standard microwave generators with solid state generators the amount of electrical energy required can be reduced as these generators provide improvement in efficiency of the electrical conversion to heat over magnetron, and other types of generators. In particular, a solid-state generator will comprise a molecular structure, such as a crystalline structure that can be molecularly excited by passing an electrical current through the structure raising the energy level of the molecules in the structure. As the molecules' energy level decreases, they release the desired microwaves into the boiler. It is noted that such solid-state structures will require less energy to produce microwaves compared to magnetrons and other microwave generators.

In some cases, the solid-state material may be arranged in a layered structure, comprising two or more layers of the desired solid-state material. In general, the layered structure will increase the surface area of the solid-state material allowing microwaves to be produced over a larger area of the material’s volume. Additionally, the electrical current may be configured to pass through the solid-state material a layer at a time, starting at one of the upper layers and moving down layer by layer. This creates a cascade effect wherein the number of microwaves progressively increases as the electrical current passes through each of the layers, allowing more microwaves to be generated using the same amount of electrical energy when compared to a solid block of the same material. The amount of microwaves produced can be increased or decreased by changing the number of layers the electrical current passes through, this increase or decrease in microwave output will change the temperature inside the boiler, as more microwaves will provide more heating within the boiler.

It is noted that in the layered structure, the layers may comprise different materials that have different energy levels. It is understood that the size of the gaps between the material’s molecular energy levels changes what energy the material can absorb and emit. Therefore, the materials may be chosen to ensure that the photons, which may include microwave photons, released by the upper layer are within the energy range that is absorbed by the lower layers, allowing the lower layers to be excited by the energy released by the upper layers. It is noted, that microwaves have relatively low energy when compared to other electromagnetic waves, therefore it may be preferable to configure the higher layers to emit photons with energies above the range for microwaves. This way, when the photons from the upper layers are absorbed by the lower layer, the lower layer may produce multiple microwaves for each photon absorbed, thereby ensuring there is a multiplication of photons produced as the energy travels between the layers of the solid-state material structure. Therefore, the materials chosen for these layers can be tailored to produce microwaves at a desired energy range, and with a desired frequency based on their energy level to ensure sufficient heating and penetration of the sprayed water within the boiler. The photon multiplication between layers will allow the system to produce more microwaves using the same amount of electrical energy when compared to layers made from a single type of material.

Another benefit of using the solid-state material is that the user can have greater control over the number of microwaves produced. This is because the solid-state material is more sensitive to the electrical current passing through it, in the context of the invention this refers to how a small change in the amount of electrical power passing through the solid-state material can create a larger change in the microwave generators output compared to other generators such as a magnetron, thereby allowing more precise control over the number of microwaves produce. This increase in precision will allow the user to more precisely control the temperature inside the boiler, by increasing or decreasing the amount of the desired microwaves released by the generator, via changes in the electrical current being supplied to the solid- state material. In cases where the solid-state material is layered, the user may further control the number of microwaves produced by changing the number of layers that are excited. Specifically, the generator may be configured to excite only one layer at a low output setting, then as the output demand, which in this case refers to the user changing a setting on the boiler or generator to increase the amount or intensity of the microwaves required, they generator will excite additional layers of the solid-state material by supply an electrical current to more layers of the solid-state material, to create the cascade as described above. To further improve the efficiency the solid- state microwave generator may comprise one or more reflectors positioned around the solid-state structure. These reflectors are made from a sheet material configured to reflect the microwaves generated by the solid-state material. In particular, the reflector will be positioned to reflect most or all of the microwaves that impact its surfaces towards the water within the boiler tank. These reflectors help to redirect the generated microwaves towards the emitter of the microwave generator to reduce the amount of energy that is wasted by directing the microwaves into the desired direction, which is towards the water to be heated, to reduce the number of microwaves that will be absorbed by the boiler casing or that escapes to the boiler’s surrounding.

The reflectors may be in the form of a sheet material or layer of reflective material placed onto the surfaces of the solid-state material that faces away from the water in the boiler tank, or the reflector may be in the form of a sheet of material or layer of material placed onto the casing of the generator and/or boiler surrounding the solid- state material. It is noted that by placing the reflector onto the solid-state material less energy will be lost as the microwaves will travel a shorter distance before being reflected in the desired direction. By placing the reflector on the casing, the user may reduce the number of reflections required to direct the microwaves as the reflectors can be shaped more easily, as there will be more space to angle the surface of the reflector, to a desired angle that will ensure the microwaves hitting the surface are directed towards the water within the boiler. It is noted that each time the microwaves are reflected they will lose some energy. Therefore, by reducing the number of reflections between the microwave being emitted and the microwave reaching the water within the boiler, the amount of energy lost may be reduced. In some cases, the system may include reflectors coupled to both the solid-state material and the surrounding casing to maximise the percentage of the emitted microwaves that reach the boiler water thereby making the energy transfer between the generator and the boiler water more efficient.

In cases wherein the solid-state material is layered, and made from different materials, the reflectors may be configured to reflect all of the photons produced by the different layers. Wherein the reflectors will reflect the photons towards the layers of the solid-state material to reduce the amount of energy loss as the energy is transferred between the different layers of the solid-state structure

The solid-state generator may also improve the safety of the user when using microwave generators as part of a boiler. First by reducing the amount of electricity required to reach a desired boiler temperature, the risk to the user is reduced. Additionally, microwave generators can include additional safety features such as fuses or safety cut-offs, including a cut-off connected to each layer of the solid-state material to help prevent the boiler casing from becoming electrified by any faults in the generator. Further, as the solid-state generators require less electrical power they can be powered by a common household outlet, rather than needing a separate generator or larger power source, therefore the generator can use the same safety features as any plug-operated device within a domestic setting. This also reduces the cost associated with operating the boiler compared to other microwave generators.

Preferably the solid-state microwave generator comprises water cooling for each of the microwave generators. Further, the system may comprise water cooling for the support circuitry, such as one or more amplifiers and/or power supplies which are configured to control the electrical power supplied to the solid-state microwave generators. Wherein water is piped through the generator in close proximity to the components being cooled to remove heat from the components via conduction.

Whilst this in principle could be carried out for a magnetron, it is a very risky procedure. As, the use of water in close proximity to the 4000-volt power source required for the magnetron, in the typically unpoliced and unregulated environment of a domestic setting in which boilers are typically employed, is an unacceptable safety risk for the occupants within the domestic setting. However, by using one or more solid-state microwave generators which use significantly lower voltages, the use of water cooling of the circuitry is more realistic.

The use of water cooling has two benefits, firstly the heat which would otherwise be wasted, as it would be ejected into the surrounding environment, can be absorbed by the water as it circulates through the generator. This water is preferably the same water that is being heated in the boiler. Preferably, the water used by the cooling system of the solid-state microwave generators is incoming cold water from the boiler system prior to being sprayed into the spray chamber. This allows the water to be pre-heated before it reaches the spray nozzle thereby increasing the temperature of the water droplets being sprayed thereby reducing the amount of heating that needs to be performed using the microwave generators. This in turn can reduce the number of microwaves that need to be produced and the amount of electrical energy needed to heat the boiler water to a desired temperature making the system more efficient.

Secondly, it allows the apparatus to work at a higher intensity than would otherwise be possible, as water cooling is very efficient it enables high-duty cycling of the solid- state microwave generator in operation. Thereby allowing the generators to produce more intense microwaves or produce microwaves for a longer period without damaging the generators.

It is noted that solid-state microwave generators typically have two emitter output settings, a continuous output or a pulsed output. The continuous output occurs when a constant electrical current is passed through the solid-state material allowing microwaves to be continuously released at a steady rate, this allows for consistent continuous heating. The pulsed output, in contrast, uses pulses of electricity typically at higher voltages to cause the solid-state material to release a pulse of microwaves these pulses will typically have a higher intensity compared to the continuous output. By changing the voltages, frequency and duration of the electrical pulses the generator can similarly change the frequency and intensity of the microwave pulses. The pulsed output can provide increased heating and water penetration compared to the continuous output but will also overheat the solid-state material and generator circuitry more quickly. The water cooling is therefore preferably used at least in conjunction with the pulsed output mode operation of the solid-state microwave generator such that higher electrical currents can be used without damaging the generator.

In the present invention, it is preferable that the spray nozzle or nozzles is positioned between two incoming solid-state microwave sources of identical or near identical wavelength. This has the advantage that the microwaves emitted from the generators can undergo constructive superpositioning, as the interference pattern created by the overlapping microwave outputs of the generators will create a predictable pattern, and will produce localised high-intensity regions of microwave energy within the volume of water released by the spray nozzle. These high-intensity regions will often have a higher rate of heating to the extent that steam may be produced more or less instantly.

This condition is greatly facilitated by the use of solid-state microwave generators as required in the present invention. For, a magnetron will typically experience deviations in the wavelength of the microwaves it emits, due to environmental conditions, such as changes in heat. This would mean that achieving constructive interference in a defined space using magnetrons is problematic and even when achieved can be unreliable as the pattern will be liable to drift. This is overcome by the use of a solid-state microwave generator, which provides greater control over the output of the generator and will provide a consistent microwave wavelength, regardless of environmental factors, as the wavelengths of the microwaved produced are determined by the type of solid-state material and structure used within the generator only. Therefore, the solid-state microwave generators can produce a consistent interference pattern based on the position of the generators relative to each other. Thereby allowing the user to easily predict the location of the high- intensity regions to ensure they rest within the path of the water released by the one or more spray nozzles.

Two or more incoming microwave sources are used in the present invention. Those sources are configured so that the overlap of the microwaves gives constructive interference in the path of at least one spray nozzle, defined by a principal axis of the outgoing spray of at least one spray nozzle. In the context of the invention, the principal axis refers to an axis defined from the point of origin to the centre of intensity of diffused radiation/water away from that point of origin creating a notional principal axis. This concentrates the increased intensity microwave energy of the high-intensity regions on the outward spray from the spray nozzles. This is also facilitated by the use of solid-state microwave emitters as the bandwidth of the microwaves produced by the solid-state microwave generator, referring to the range of frequencies present within the microwaves produced by and emitted by the generator, is typically narrower than the bandwidth produced by a magnetron. This again ensures that the interference pattern produced by the solid-state generator microwaves is more predictable allowing the high-intensity regions, to be positioned along the principal axis of one or more spray nozzles to ensure the maximum amount of energy is transferred from the microwaves to the water in the shortest amount of time.

Microwave generator(s) and hence emitter(s) of the present invention preferably emit microwaves in one or more of the following frequency bands 915 ± 13 MHz, 2450 ± 50 MHz, and 5800 ± 75 MHz. This is more readily and more accurately achieved using a solid-state microwave source as opposed to a magnetron which can typically have a frequency spread of a range such as ±70 MHz even at lower frequencies. As noted above these more accurate bands allow the interference pattern produced by using multiple generators or multiple emitters coupled to a single generator to be more readily predicted allowing the user to position the spray nozzles to ensure the maximum amount of water in the spray chamber intercepts one or more high-intensity regions within the interference pattern.

In the claimed invention, it is preferable for the outward spray of one or more spray nozzles to preferably have a narrow spread, for example, the spread of the sprayed water may be a cone with an angle of between 10 and 55 degrees, as defined by the angle between the sprayed water at the point of origin and the principal axis as defined above. This produces a less diffuse jet of water and therefore concentrates more of the water’s volume on the constructive interference high-intensity regions of the microwaves.

The use of constructive interference is particularly applicable to microwaves as they have a wavelength in the range of 1 to 15 centimetres and therefore accurate positioning relative to the wavelength between the microwave source and the nozzles is eminently practical. The preferred wavelength for use in the present invention is between 2 and 13 centimetres, most preferably between 3 and 6 centimetres. These allow progressively more frequent, in terms of distance relative to the size of the tank, there is overlap to create constructive interference.

That constructive interference may be accompanied by destructive interference is not a detriment as destructive interference does not inherently lose energy from the overall energy of the generated microwaves nor take away energy from the heating process.

The solid-state microwave generator may be of any conventional sorts, solid-state microwave generator, wherein the generator uses a semiconductor-based microwave source. Suitable solid-state microwave sources are Tunnel Diode, Gunn Diode, Read Diode, IMPATT Diode, BARITT Diode, TRAPATT Diode, Varactor Diode.

An example being: a GaN-based solid-state microwave generator (RIF58800-20SG, of RFHIC Co., Anyang, South Korea), with a minimum frequency of 5725 megahertz, maximum frequency of 5875 megahertz, output power 800 watts and operates at 50 volts DC allowing the generator to be powered by a standard domestic electrical outlet.

Tin a preferred example the generator above was operated at 5800 megahertz and 800 watts. The GaN solid-state microwave generator was water-cooled wherein the cooling water was then fed into the output spray of the nozzles for maximum energy efficiency.

In comparison to an equivalence magnetron 2M261 , Panasonic® Co., Tokyo, Japan the solid-state device gave a more stable microwave frequency and the region in which constructive interference occurred was stable over a period during the period of observation, being several minutes. This was also observed with different throughput rates of water spray.

In addition, the heat dissipated by the microwave generator itself could not be captured with a magnetron, due to the risk of putting water in close proximity to the high voltage magnetron, but was successfully captured by the water cooling with the solid-state device. Therefore, the boiler saw an improvement in efficiency when using the solid-state generator as described above. Additionally, the inclusion of a water-cooling system not only helps to further improve the boiler efficiency but will also allow the generators to operate for longer periods, and/or at higher energy intensities, with a reduced risk of damaging the generator’s components, such as the solid-state material source or the supporting circuitry.

It is also noted that the use of solid-state microwave generators can help improve the efficiency of the boiler by reducing the need and time required for maintenance.

More specifically, each of the solid-state microwave generators coupled to the boiler would comprise a unit. Each unit comprises the solid-state material, a domestic plug for sourcing power, or another suitable power source, and the necessary circuitry to operate the generator and control the microwave output produced as described above. Should one or more units require maintenance or become damaged the user can simply replace them with another identical unit. This replacement process may be performed in a manner of moments by decoupling one unit, for example by removing one or more fasteners connecting the unit to the boiler housing, and coupling the new unit in its place. This will reduce the amount of downtime required when repairing or performing routine maintenance on the boiler.

Drawings

The present invention is illustrated by means of the following drawings in which like features are designated with like numerals. The figures provide

Figure 1 : shows a blow-up view of the components used to form the claimed invention

Figure 2: shows an example boiler as per the claimed invention.

Figure 3: shows an example boiler as per the claimed invention, which uses a two- tank system.

The features of the drawings are listed as follows:

10 - Solid-state microwave generators

20 - Shielding layer

30 - Water tanks

40 - Spray nozzles

50 - Pumps

60 - Step-up transformer (if required)

70 - Outer casing/housing

72 - Front panel

101- Microwave (notional peak intensity of outgoing wave)

111 - Line of Constructive Interference defined by overlapping peak intensities

121 - Constructive Interference

131 - Water Spray Cone

135 - Water droplet Detailed description

The claimed invention provides a microwave heated boiler, as an eco-friendly alternative to the traditional gas boiler, where in the microwave boiler comprises the following components, as depicted in figures 1 and 2:

Microwave (MW) generators 10: the invention utilises one or more microwave generators 10, as a means of heating the water inside the boiler tank 30, as the water absorbs the microwaves. More specifically the microwaves are used to heat the water as it enters the boiler tank 30, as the water would preferably enter the boiler as a mist or spray of droplets, these droplets increase the total surface area of the water, thereby increasing the probability of the microwaves being absorbed. The MW generators 10 may be coupled to the sides of the boiler tank or to the top of the boiler tank. The MW generators 10 is a solid-state microwave generator. Note that each generator may comprise an emitter mounted to the side of the generator facing the water tank, to direct the generated microwaves towards the water, while the remaining sides may be encased in a layer of shielding 20, to help prevent the generated microwave from leaking into the surrounding environment, by including both the emitter and the shielding, the microwave generated by each generator can be directed into the boiler tanks with no risk of escaping to the boiler’s surroundings. In operation the MW generators 10 may be able provide continuous heating, changing the intensity, and/or amplitude, of the microwaves generated in order to control the temperature of the water in the tank 30, for example a lower intensity being used for lower temperatures, or may instead operate periodically activating to raise the water temperature to a desired value before deactivating again, in this mode it is likely that the microwaves will be generated at a higher intensity/amplitude to heat the water rapidly.

It is noted that regardless of the mode used, this method of heating water provides a greener alternative to current gas boilers, and may require less power to operate compare to electric water heating. In some cases, the power from a standard wall outlet may be sufficient to run the one or more MW generators 10 attached to the boiler, in other cases the boiler may come with its own power supply, such as a solar panel, regardless of the method used the claimed boiler does not require a large amount of power to operate. Additionally, as the MW generators 10 do not produce any emissions, therefore the microwave boiler is more eco-friendly and also does not need to be ventilated, meaning the boiler does not need to be mounted to an external wall, and can instead operate from anywhere in the home with a suitable power supply.

Additionally, the boiler may be configured to generate high pressure steam, said steam may be used when the boiler is powered by a turbine as a means to keep said turbine turning in an emergency, wherein power to the turbine is interrupted/lost. In these cases, the boiler is configured to pump a portion of the heated water back through the spray nozzle, thereby exposing this portion of water to additional heating, in order to further heat the water to produce steam. Note that in some cases the heated water may be pump to a secondary tank, or a secondary spray chamber, inside which it will be heated again to form steam. In some cases, the secondary tank/spray chamber may be smaller so as to increase the pressure of the steam held within. These embodiments may also cycle the portion of heated water through the spray nozzles of the main or secondary tank/spray chamber multiple times in order to heat the water to the sufficient temperature to produce a sufficient quantity of steam. As this steam will only be needed in emergencies it is preferable to have the ability to store the steam until it is needed, additionally if the steam is stored within the same tank as the heated water the steam may interfere with the heating process as the steam may become dense enough to shield the droplets that are sprayed into the water tank. For these reasons it would be preferable to include the secondary tank to store the steam until it is needed, note that this secondary tank may continuously cycle the portion of water fed into the tank so as to constantly heat this portion of water to prevent it cooling/condensing.

The one or more MW generators 10 may also be part of a microwave generating unit. Wherein each unit comprises the one or more MW generators 10, with shielding 20 and an emitter for each generator, the units may also comprise control systems for each of the generators 10 to control the output of the emitters, such as changing the magnitude, or intensity, of the emitters’ output, or change the emitters’ modes from a constant output to a pulsed output. It is noted that the constant wave output would allow the boiler to constantly heat the water within the boiler, providing a means to heat the water after it is pooled within the bottom of the water tank 30, however the intensity of the microwaves will be relatively low compared to the pulsed output so the rate of the temperature increase within the water, and therefore the heating process, may be slower when compared to the pulsed output. Whereas the pulsed output provides short intense bursts that may provide a faster rate of energy absorption, and therefore a faster heating process, but may be less penetrative than the constant wave, meaning the pulses may be less effective at keeping the water in the water tank 30 warm as it cannot penetrate the pooled water. As both modes have their own benefits the user may choose the mode they find most desirable, or in cases where the boiler includes multiple MW generators 10, the user may set different generators to different modes, to gain the benefits of each. The units may also include one or more sensors for monitoring the generators 10 which may detect faults in the unit, fans for cooling the generator components to prevent overheating, and/or a power input for powering the components of the unit, which may allow the unit to be disconnected from the power source in order to be safely removed it from the boiler, during maintenance or when a fault is detected by the sensor. It should also be noted that instead of air-cooling the MV generators 10, the units may include a water-cooling systems or other suitable cooling systems, like those found in computers. However, one embodiment of the cooling system may use the water flowing into the water tank 30 as the cooling medium within the cooling system. Preferably this water would pass over the microwave units just before being sprayed into water tank 30, as this is likely when the water is at its coolest temperature, meaning the temperature difference between the water and the components of the generator units will be at its greatest, this higher temperature gradient may improve the rate of heat transfer between the unit and the water, thereby allowing more heat to be transferred to the water. Such a cooling system will also help in improving the efficiency of the water heating process within the boiler by using the microwave units to pre-heat the water before entering the water tank 30, as the process of heating the water with microwaves is not dependent on a heat gradient this pre-heating would not lower the rate of energy transfer within the tank, but may help bring the water to a higher temperature. It should also be noted that a benefit of using such units, is that should a unit fail, it can be easily removed and replaced with a working unit, after which the faulty unit may be disposed of, or sent to be repaired. Making it easier for the user to do repairs to the boiler when necessary, and means the user does not need to go for long periods of time without hot water, while waiting for repairs. Spray nozzles 40: to improve the effectiveness of the MV generator-based heating the boiler may utilise one or more spray nozzle 40. Wherein the nozzles 40 are configured to spay the water entering the boiler tank 30 to form droplets, or a fine mist, which can then be heated by the microwaves, after which the heated water pooling together at the bottom of the boiler tank 30 ready to be used. This process helps to improve the effectiveness of the microwave hearting, as each droplet is a separate volume of water which will require significantly less energy to heat, these droplets also increase the amount of surface area that is exposed, thereby increasing the chances of the generated microwaves being absorbed. This is especially true, when compared to a system that tries to heat all of the water in the tank at once, as the greater volume would mean more energy is required to heat the water to a desired temperature, increasing the power consumption of the boiler. Additionally, when the water is pooled at the bottom of the tank, the microwaves may only be able to penetrate a certain depth of the water, as the water at the top of the tank may be shielding the water beneath, meaning that only the top of the water is being heated, and the rest of the water would be heated slowly via convection currents, which would mean the process of heating the water in the boiler to a desired temperature would take significantly more time. Therefore, by heating a spray of water, the water in the boiler can be heated faster, and would require less energy to reach the desired temperature. Note that is may also be possible to have the microwaves continue to heat the sprayed water once it has pooled at the bottom of the tank, but as the water is already heated this process would be more efficient due to the lower temperature difference between the sprayed water and the pooled water.

Similar to the MW generators 10, the spray nozzle 40 may be mounted to the sides or top of the tank 30, though it is noted the nozzles 40 should preferably be in a position perpendicular to the position of the microwave generators 10, as this may help improve the overlap between the emitted microwaves and the water flow from the nozzle. Thereby improving the efficiency of the heating process, by ensuring the largest possible volume of the sprayed water is exposed to the generated microwaves. It is noted that different types of nozzles may be utilised to get different spray patterns, for example, the nozzle 40 may be configured to produce a flat splay, thereby shaping the water into a thin sheet to again improved exposure to the microwaves, as the thin sheet ensures the microwaves can fully penetrate the sprayed water. In some cases, the nozzles 40 may produce a course flow, for though a course flow would spray the water in a larger volume, which runs the risk of the microwaves not fully penetrating the sprayed water, such a flow may help to bypass, or remove any blockages with the nozzle itself. Thereby providing the boiler with a means of removing any blockages that form, without the need to remove the nozzle from the boiler. In some cases, the nozzles 40 may be configured to produce a cone spray, such a spray would also ensure that the water enters the boiler tank as a thin layer for improved penetration, but would potentially also inject a greater volume of water at once providing a more efficient flow, this flow would be preferably when the water is sprayed from the top of the tank, in such cases MW generators 10 may be mounted on opposite sides of the flow, to help ensure that one side of the cone does not block the microwaves from the other side of the water flow. And in some embodiments the nozzle 40 may be configured to produce a fine mist, thereby reducing the volume of the water droplets in the flow, and increase the surface area of the droplets, thereby further reducing the energy needed to heat them, though such a mist may cover a large volume, or be so dense, to the point where the droplet furthest from the MW generators 10 may not be heated in time, as it is shielded by the rest of the mist. It is, noted that in any case, it is important that as much of the surface area of the sprayed water is exposed to the microwaves as possible, as there will be little to no convection to transfer heat between the droplets, and though this can be achieved by using high number of smaller volume droplets, with little spacing between them, there must be a balance to ensure the droplets do not shield one another from the microwaves, therefore it is preferred that the spray chamber/portion of the water tank that received the water from the nozzle houses a relatively low volume of water at a given time, therefore it may be considered that the flat or cone spay may be preferable as the shape of the flow ensures there is little to no shielding between droplets, though at a low pressure the mist spray may be preferable as it produces the smallest droplets and therefore exposes the largest surface area.

Regardless of which nozzle design is used, it is noted that the nozzles 40 would preferably be towards the top end of the water tank 30, in order to increasing the path, the sprayed water has to travel before reaching the pool of water at the bottom of the tank. In doing so, the boiler may increase the likelihood of the sprayed water being heated before pooling with the rest of the water, as the droplets or mist will be exposed to the microwave for a greater time, thereby increasing the probability of the individual droplets absorbing sufficient microwaves to be heated by the time it reaches the bottom of the water tank. It is also noted that the water tank 30 should not be completely filled with water, as if it was there would be no room to produce the desired spray described above. Additionally, when there is more open space within the tank 30, there will be a longer path the sprayed water will need to travel before reaching the pooled water, therefore the more space in the water tank the higher the probability that the generated microwaves will be absorbed by a water droplet, for this reason it may be preferable to have the water tank be no more than half full at any given time. Alternatively, the water tank may include a separate spray chamber, wherein the spray nozzles 40 spray water into the spray chamber to be heated before the heated water flows into the water tank 30.

Pumps 50 and water tanks 30: the boiler may also comprise one or more pumps 50 for pumping the water in and out of the boiler, similar to most boiler designs. However, in most traditional boilers the pumps used are design to output a large volume, typically with a lower pressure output. Such pumps may not be suitable for the claimed system as the nozzles 40 will require a relatively high pressure to create the required spray. Therefore, the claimed boiler may use a high-pressure pump for pumping the water in and out of the tank. Alternatively, the boiler may use a plurality of pumps, which includes at least one low-pressure pump for pumping water round the system in a high volume, and at least one smaller high-pressure pump for pumping water into the spray nozzles 40 to increase the pressure of the water flowing to the nozzles 40, to ensure the nozzles can produce a fine spray, as the water enters the tank 30.

In some embodiments the boiler may comprise a single water tank 30 as depicted in Figure 2, for receiving the heater water, to be stored before use, as previously mentioned this water tank 30 may also include a spray chamber for receiving and heat the sprayed water before storing the heated water in the water tank 30. But in the preferred embodiment the boiler of the present invention may comprises two tanks 30, as depicted in figure 3, one for producing hot water for water systems, such as taps and showers, and a separate tank for producing hot water for a central heating system. By using two tanks 30, the boiler can supply both systems simultaneously, without the need to priorities one system over the other, meaning that using hot water from outlets such as sinks and showers does not affect the central heating system, and vice versa. Note that in such a two-tank system the boiler will require at least two pumps 50, one for each tank 30. And in some embodiments, there may be a need for four pumps, comprising a low-pressure pump for moving a large volume of water through the respective system, and a smaller high-pressure pump for pumping water through the spray nozzles 40 of each tank 30.

Additionally, it is noted that each tank 30 used in the disclosed boiler should comprise a material that may either absorb or reflect the generated microwaves, or may have a coating on the inside of the tank made from such materials, so that the generated microwaves do not escape the tank 30. It is noted that by using the reflective material the microwaves may be reflected back towards the water in the tank 30 to improve the efficiency of the heating process, by exposing more of the water to the generated microwaves, thereby increase the chance of the microwave being absorbed. However, as mentioned the casing, or the inner lining, may be made of a material that will absorb the microwaves instead, this will result in the casing of the water tank 30 heating up, and may therefore provide heat to the water in the boiler, especially to the pooled water that the microwaves may not be able to penetrate. In the cases wherein the tank 30 is made of a material that absorbs the excess microwaves, the boiler may comprise a series of pipes that pass the water over the sides of the tank 30 before it reaches the spray nozzles 40, this way the water can absorb heat from the tank to pre-heat the water before it enters the water tank, this can prevent the tank 30, from overheating and improve the heating process by reducing the time/energy needed to heat the water to the desired temperature.

Also as mentioned the claimed boiler requires the water entering the boiler to be sprayed into droplets, or a mist before being heated by the microwaves, therefore the one or more water tanks 30 may requires a spray chamber, this may be a portion of the water tanks volume, or a separate chamber that then feeds the heated water into the water tank. As previously mentioned, it is preferable for the boiler to have a means of keeping the water warm after it has pooled in the water tank, usually by having the water tank exposed to the generated microwaves, therefore of these options it is preferable that the spray chamber be part of the water tank 30 itself. In particular the water tank can be seen more as a canister wherein only a portion of the water tank 30 will be filled at a given time, the empty portion of the water tank will be coupled to the spray nozzle and will act as the spray chamber. To achieve this the water tank 30 would preferably only hold enough water to fill about half the tank or less, when the water pools at the bottom of the tank, wherein the spray nozzles will spray the droplets or mist into the empty top half of the chamber to be heated by the microwaves. It should also be noted that when a spray chamber is used it may be preferable for the spray chamber to be made of, or lined with a material that can reflect microwaves, allowing the unabsorbed microwaves to be redirected towards the sprayed water, to increase the chance of absorption.

It should also be noted, that each of the pumps 50 and tanks 30 used in the boiler may be design to couple with a range of different water pipes. Allowing the user to maintain the pipes to their current boiler, and simply couple them to the new tank 30/pumps 50, when installing the claimed boiler, thereby allow easy installation. It should also be noted that similar to the MW generators 10, the pumps 50 and water tanks 30 may comprise their own units that can be easily coupled to, or removed from, the boiler, and therefore may be easily replaced if they are faulty.

Power supply: In order to use the above-mentioned pumps 50 and microwave generators 10 the claimed boiler requires a power supply. In some embodiments this power may be supplied from a standard wall outlet, which feed electricity into a step- up transformer 60, which may be mounted within the boiler, that will then output the required power to the pumps 50 and microwave generators 10. Note that in embodiments wherein the boiler has multiple tanks 30, there may be a separate transformer 60 for each tank 30, each supplying power to the pumps 50 and microwave generators 10 of their respective tanks 30. In other embodiments the boiler may have its own power supply, such as a solar panel, that may also feed power into a transformer 60 within the boiler before powering the pumps 50 and/or MM generators 10, though such external power supply may be able to generate the necessary power for the boiler without the need for the above-mentioned transformers 60. In some cases, the boiler may be powered by a turbine, in such cases as previously mentioned the boiler may be configured to produce steam in order to turn the turbine in the case of an emergency, when power has been interrupted or lost, until the power returns to normal, this system may require an additional tank/chamber for storing and generating said steam.

Outer casing/housing 70: the boiler should preferably include an outer casing/housing 70 which would house the above-mentioned boiler components, such a housing 70 may help make the boiler more aesthetically pleasing, and may also prevent water leaking from the boiler from entering the external environment, should one of the tanks 30, nozzles 40 or pipes within the boiler begin to leak. This outer casing may also be made from a material that could shield the surroundings from the microwaves generated by the MW generators 10, by being made from a material that can absorb such microwaves, or a material that may reflect the microwaves back towards the water tanks 30. The housing 70 may instead have a lining on the inside of the housing 70 made of a material that can absorb the microwaves or reflect them back towards the water tank 30, using such a lining may help to reduce the overall weight of the housing 70, when compared to an entire housing made from the same material. It should be noted that the housing 70 may be removeable, or have a removable font panel 72, to allow the user to access the different components within the housing more easily.

Control system: The boiler features a control system that may be coupled to boiler, remote from the boiler, or preferably a combination of both, thereby providing additional redundant control means should one of the control systems fail. The claimed boiler may feature a display mounted to the water tank 30 or housing 70, to show the status of the boiler, as well as controls coupled to the display, or the surrounding housing, for controlling the water temperature and water levels within the tank 30. It is noted that these controls may also be remote from the boiler itself. In these cases, the controls may comprise a mobile hub or controller, that would comprise the above-mentioned display and boiler controls, which can control the boiler remotely, possibly through a Wi-Fi connection, or internet of things (loT) connection. In other cases, the mobiles controls may be in the form of an application on the user’s mobile devices, such as a smartphone, smartwatch, laptop. These mobile control systems will allow the user to monitor and control the boiler regardless of their current location, though the boiler may as mentioned still have manual controls on the boiler itself as a backup control system. Also, in systems that utilise generator units with monitoring sensors, the control system may also be configured to alert the user to any detected faults within the microwave generator units, and may also be configured to control the outputs of the MV generators 10 and/or generator units.

By using the above-mentioned boiler system, the claimed invention provides an eco- friendly alternative to gas boilers. By using microwave generators to heat the water within the boiler, wherein the microwave generates uses electricity and have a low power consumption, the boiler does not produce carbon emissions and has a reduce carbon footprint when compared to other gas boiler alternatives.

Claims

1 . An eco-friendly boiler comprising: a water tank, wherein a portion of the water tank comprises a spray chamber; one or more spray nozzles configured to spray water into the spray chamber of the water tank; one or more microwave generators coupled to the spray chamber and configured to emit microwaves towards the water emerging from the spray nozzle or nozzles; and wherein a source of microwaves used within the microwave generators is a solid-state microwave generator, configured to use a structure made from a predetermined solid-state material as a source for converting electrical energy into microwaves; wherein two or more incoming microwave sources are present and those sources are configured such that the overlap of the microwaves gives constructive interference in the path of the water produced by at least one spray nozzle.

2. The boiler of claim 1 where the solid-state microwave generator(s) further comprise a water-cooling system configured to pipe cooling water over or proximate to the surface of the microwave generators.

3. The boiler of claim 2, wherein the cooling water is configured to be piped over or proximate the solid-state material.

4. The boiler of claims 2 or 3, wherein the cooling water is configured to be piped over or proximate to a support circuitry of one or more solid-state microwave generators.

5. The boiler of claims 2 to 4, wherein the water of the cooling system after is directed towards the output of the one or more spray nozzles.

6. The boiler of claim 1 or claim 2 further comprising solid-state microwave generators configured to operate in a pulsed output mode.

7. The boiler of any prior claim comprising one or more spray nozzles positioned between two incoming solid-state microwave sources of the same or substantially the same wavelength.

8. The boiler of any prior claim in which the outward spray is directed to being a cone angle centred upon the path of the spray water, of between 10 and 55 degrees.

9. The boiler of any prior claim comprising microwave generators with a microwave emitter or emitters emitting microwaves in one or more of the following frequency bands 915 ± 13 MHz, 2450 ± 50 MHz, and 5800 ± 75 MHz.

10. The boiler of claim 9 comprising a microwave emitter or emitters emitting microwaves in the frequency band 5800 ± 75 MHz.

11 .The boiler of any prior claim wherein the solid-state microwave generator is a semiconductor-based microwave source.

12. The boiler of claim 11 wherein the solid-state microwave sources is one or more of a Tunnel Diode, Gunn Diode, Read Diode, IMPATT Diode, BARITT Diode, TRAPATT Diode, Varactor Diode.

13. The boiler of any prior claim, wherein the solid-state material source, comprises a layered structure made from two or more layers each layer made from a solid-state material.

14. The boiler of claim 13, wherein an electrical current is passed through each layer of the layered structure sequentially.

15. The boiler of claim 13, wherein the electrical current to each layer is controlled independently.

16. The boiler of claims 13 to 15 wherein the layers of the layered structure are made from the same solid-state material.

17. The boiler of claims 13 to 15, wherein the layers of the layered structure are made from different solid-state materials, wherein the material of each layer is chosen to emit photons that can be absorbed by the material of the lower layers to be converted into one or more microwaves, thereby producing photon multiplication as the photons travel through the layers of the structure.

18. The boiler of any preceding claim wherein the boiler further comprises one or more reflectors configured to reflect the emitted microwaves and the reflectors are positioned to reflect said microwaves towards the sprayed water.

19. The boiler of claim 18 wherein the reflectors are coupled to the surface of the solid-state material.

20. The boiler of claim 18 wherein the reflectors are coupled to the housing of the boiler and/or microwave generator.

21 .The boiler of claim 18, wherein the reflectors are coupled to both the surface of the solid-state material and the housing of the boiler and/or microwave generator.

22. The boiler of any prior claim wherein the solid-state microwave generators are powered by a domestic electrical outlet.

23. The boiler of any preceding claim wherein the microwave generator comprises a unit containing one or more solid-state microwave generators, wherein the unit is configured to be coupled to the housing of the boiler; and wherein each of the solid-state microwave generators can be removed and replaced from the unit.