Apparatus and method for heating fluids

An apparatus for heating a liquid includes a housing having an internal chamber and a rotor disposed in the chamber. The rotor is preferably cylindrical and operates inside a bore provided by the housing without touching, the shape of the bore preferably being parallel with the exterior surface of the rotor, and a series of openings disposed over the rotor surface. At least one internal passageway in the rotor and elements for: pre-heating some or all the incoming fluid in the chamber; priming the chamber initially; cooling certain temperature sensitive components; injecting fluid into a partially evacuated volume; developing a vacuum state during operation expeditiously.

BACKGROUND OF THE INVENTION

The invention relates generally to the heating of liquids, and specifically to those devices wherein rotating elements are employed to +generate heat in the liquid passing through them. Devices of this type can be usefully employed in applications requiring a hot water supply, for instance in the home, or by incorporation within a heating system adapted to heat air in a building residence. Furthermore, an economic portable steam generator could be useful for domestic applications such as the removal of winter salt from the underside of vehicles, or the cleaning of fungal coated paving stones in place of the more erosive method by high-pressure water jet.

Of the various configurations that have been tried in the past, types employing rotors or other rotating members are known, one being the Perkins liquid heating apparatus disclosed in U.S. Pat. No. 4,424,797. Perkins employs a rotating cylindrical rotor inside a static housing and where fluid entering at one end of the housing navigates through the annular clearance existing between the rotor and the housing to exit the housing at the opposite end. The fluid is arranged to navigate this annular clearance between static and non-static fluid boundary guiding surfaces, and Perkins relies principally on the shearing effect in the liquid, causing it to heat up. A modern day successor to Perkins is shown in U.S. Pat. No. 5,188,090 to James Griggs. Like Perkins, the Griggs machine employs a rotating cylindrical rotor inside a static housing and where fluid entering at one end of the housing navigates past the annular clearance existing between the rotor and the housing to exit the housing at the opposite end. The device of Griggs has been demonstrated to be an effective apparatus for the heating of water and is unusual in that it employs a number of surface irregularities on the cylindrical surface of the rotor. Such surface irregularities on the rotor seem to produce an effect quite different than the forementioned fluid shearing of the Perkins machine, and which Griggs calls hydrodynamically induced cavitation. Also known as the phenomena of water hammer in pipes, the ability of being able to create harmless caviation implosions inside a machine without causing the premature destruction of the machine is paramount. The Giggs machine would seem to take time to reach steady state conditions before reaching maximum efficiency, due most likely to the difficulty of such surface irregularities becoming sufficiently primed with fluid at stary up. Such surface irregularities, at the commencement of rotor rotation, may be largely empty of fluid, and as such, there is likely a time lag before sufficient fluid is, by the severe turbulent flow conditions, in the gap between rotor and housing, able to enter into these surface irregularities to produce the desired hydrodynamically induced vatitational heating of the fluid flowing through the machine. A further feature of Griggs is that the maximum effect is limited by the size of volume pocket void that exists for each surface irregularity. For instance, a surface irregularity in the form of a drilled hole has a certain diameter and depth which determines the maximum quantity of fluid it can hold. During operation of the Griggs machine, this quantity of fluid is reduced, most likely reduced quite substantially in order to create the desire effect of a very low-pressure region in and about the hole. For certain applications, there may be advantage through the deployment of deeper holes in the rotor, as compared to the depth of holes taught by Griggs, for improved shock wave transmissions from the cavitiation implosion zones to maximum power efficiency in performance. Furthermore, the protection of bearings and seals against deterioration caused by high temperatures and pressures in the fluid entering and exiting the machine is important. The use of detachable bearing/seal units mounted externally to the housing is a known solution that is used to space the bearing and seal members further away from the hot regions of the machine. However, there would be advantage if some or all the bearings and seals could be disposed in a cooler region in the machine, thereby saving the additional complication and expense of having to use such detachable bearing/seal units. There therefore is a need for a new solution whereby the effects of high temperatures and pressures are less harmful to such bearings and seals.

The present invention seeks to improve on some or all of the above mentioned limitation of earlier machines without undue complication and whereby the cavitational heating of the fluid by shock wave transmissions from the cavitation implosion zones can be maximized.

There is also a need for a new solution whereby such surface irregularities confronting the annular chamber, as well as any internal voids or cavities within the rotor itself, can be primed with fluid prior to the commencement of rotation of the rotor.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a new and improved mechanical heat generator, capable of operating under strong vacuum conditions, that addresses the above needs.

A principal object of the present invention is to provide a novel form of water heater steam generator apparatus capable of producing heat at a high yield with reference to the energy input. It is a still further object of the invention to provide a method for doing so.

It is a still further object of the invention to alleviate or overcome some or all of the above described disadvantages of earlier devices, and thereby be able to generate an improved shock wave transmission by the cavitiation implosion zones towards maximizing the effect for the purpose of obtaining an improved performance from the unit.

It is a preferred feature of the invention that the entry point for the fluid entering the chamber is central or close to the center axis of the drive shaft, preferably coincident with the axis of rotation of the rotor. The fluid, on entering the device and arriving in the central chamber to come into contact with the revolving rotor, is propelled radially outwards in a generally spiral path, until redirected by the interior shape of the housing. The fluid on entering the annular clearance between rotor and housing is heated, firstly by the shearing effect on the fluid between static and dynamic opposing boundary surfaces, and secondly from the deployment of numerous openings or cavitation inducing depression zones on at least the exterior surface of the rotor. Although it is a preferable feature of this invention to position a peripheral exit passage in the housing for the heated fluid to leave the device at a location described as radially outwardly of the annular clearance, the exit passage may alternatively be positioned radially inwardly of the annular clearance to be adjacent the flanking wall of the rotor. With respect to Griggs, both the fluid entry and exit points have the same elevation in the internal chamber and are both positioned radially inwards of the annular heat generating working chamber. It should be noted however, that may of the inventive improvements described in the present invention may also apply to good effect were the entry and exit passages positioned in the manner taught by Griggs, and for that matter, when the housing are prepared to accept additional detachable bearing/seal units.

As the fluid rides over each opening or depression zone in turn, it is squeezed and expanded by the vacuum pressure conditions occuring in the zone, and the condition of cavitation together with accompanying shock wave behaviour, as the fluid traverses across the surface of the rotor, liberates a release of heat energy into the fluid. Although natural forces such as cavitation vortices are known to occur in nature, the forces to be generated in the present invention are usually viewed as an undesirable consequence in man-made appliances. Such destructive forces, in the form of cavitation bubbles of vacuum pressure, are purposely arranged to implode within locations in the device where they can do no destructive harm to the structure or material integrity of the machine. In this respect, certain rotors here disclosed feature openings or depression zones in the form of holes arranged to interconnect, either directly or via a flow restricting throttle, with an internal chamber provided in the interior of the rotor towards broadening the occurance in the number and range of resonant frequencies for an additional influence in the formation of cavitation bubbles.

It is therefore an aspect of this invention to be able to rapidly and successively alter and disrupt the path of fluid flowing between the rotating and stationary elements in the annular clearance as it passes across these depressions which during operation of the device may become largely empty vessels of vacuum pressure, and where the deployment of openings or depression zones act in diverting a quantity of the passing fluid into these openings or depression zones for the formation of cavitation vortices inside these voids and their attendant shock waves and water hammer effects. In addition, certain of the rotors disclosed in the present invention allow the admission of further fluid into these voids from a chamber internally disposed in the rotor. The fluid once subjected to water hammer returns back to the annular passage with an increase in temperature and this continues in a continuous process until the fluid leaves the device. As such, each of said openings or depression zones becomes in effect individual heating chambers for the device. For certain applications, some or all of such individual heating chambers may be deeper in depth than deployed previously for the creation of an amplified cavitational effect by the device.

It is also a preferred feature of this invention to minimize the risk of bearing and seal failure. In this respect, the examples show that the positioning of the fluid inlet axially adjacent the inner end of the drive shaft has the principle advantage that the support bearing receives a copious supply of cooling fluid, while also removing the requirement for any type of seal member to be located between the housing and shaft at this end of the device. The transmission of power to the device without any direct mechanical connection would remove the requirement for a seal member at the opposite end of the device. However, when required, fluid passageways can be incorporated to provide the seal with sufficient fluid, at least for cooling and/or lubrication purposes.

In one form thereof, the invention is embodied as an apparatus for the heating of a liquid such as water, comprising a static housing having a main chamber and at least one fluid inlet and at least one fluid outlet in fluid communication with the main chamber. Preferably, the fluid inlet and/or the fluid outlet are located in a static member such as the housing. A rotor disposed centrally in the chamber and mounted for rotation within the chamber about an axis of rotation, and the rotor in spaced relation with respect to the housing to provide a generally annular passage for fluid to travel from the inlet towards the outlet. The rotor is provided with at least a single interior passageways forming a vessel therein as well as a series of openings formed on an exterior surface thereof confronting fluid in the passage. The interior chamber is the rotor may initially be primed with fluid prior to commencement of rotor rotation. Once the rotor is rotating at high-speed, fluid entering the annular passage either from one end; or by entrance means provided along the surface length of the rotor; or a combination of one end as well as by entrance means provided along the surface length of the rotor; is caused to be heated as it travels in said annular passage in a direction towards the fluid outlet by passing a multitude of cavitiation implosion zones in about said openings. Preferably, the rotor and the drive shaft have a common axis of rotation. The rotor element can be said to interact with the surrounding housing to produce two quite distinct regions or heating stages, the first region being the annular clearance between rotor and surrounding housing which acts as the primary heat generating region or stage, the second region being disposed internally in the rotor element and acting as a pre-heating stage for at least a proportion of the incoming fluid from the inlet, and where the series of openings on the exterior surface of the rotor are communicating with at least one of these two regions.

A fluid source tank should preferably be situated above the height of the device in order to provide the device with water at the inlet connection. However, mains water pressure may alternatively be used at the inlet, with a pressure reducing valve to lower the pressure level, if necessary.

Other and further important objects and advantages will become apparent from the disclosures set out in the following specification and accompanying drawings.

DETAILED DESCRIPTION OF THE FIRST ILLUSTRATIVE EMBODIMENT OF THE INVENTION

Referring toFIGS. 1 to 4, the device shows a housing structure comprising rear housing member1, front housing member2and a tubular central housing member3. Housing member3with bore15is a sleeve which spans across from end face6of rear housing member1to the face7of the front housing member2and the space inside is the main chamber of the device. Four screws4are arranged to engage members1,2with member3thereby sandwiched in-between. Drive shaft5is shown protruding out from front housing member2inFIG. 1. The rear view of housing member1inFIG. 2shows threaded fluid intake connection10, also called the “inlet” or “intake”, and well as fluid ports11which become more clearly depicted with reference toFIG. 3. The inlet10is shown rather large in diameter in order for access to be obtained for a drill in order that fluid ports11can be created, the ports11fluidly communicate inlet10with the end face6of the rear housing member1. In later embodiments, ports11are omitted so inlet10need not be so large.

As shown in these various embodiments, the interior of the heat generating device is an internal or main chamber largely occupied by the rotating component, and the rotatable unit, typically called a rotor. The rotor resides radially inwardly of bore15in the main chamber. The rotating component is part drive shaft5and part rotor. The rotor comprises two elements12,13, the first element is the central portion12preferably formed integrally with drive shaft5, and the second element is a sleeve portion13and which is a heat shrink on central portion12. The rotor sleeve portion13with exterior surface14is sized accordingly to have the required working clearance in bore15to allow the passage of fluid, this annular passage with a working clearance may alternatively called annular fluid volume. Although rotor exterior surface14and bore15are shown to be parallel with respect to the longitudinal axis of the drive shaft, either or both may alternatively be inclined. The term “annular passage” here used in the present invention is intended to also cover such variations in the outer shape of the rotor as well as the shape of the bore, for example, a thin cone-shaped annular passage disposed between the static housing and the rotatable rotor unit.

Drive-shaft5is supported in the housing by a pair of bearings, plain bearing20disposed in rear housing member1and bearing22disposed adjacent rotary seal21in front housing member2. Seal21is preferably disposed on the opposite axial side of the housing to where the inlet10is disposed. Seal21may typically be a rotary lip seal or double lip seal capable of working under pressure as well as under negative pressure conditions, although it should be noted all embodiments may easily be adapted to incorporate other types of seals that are readily available. For instance, a spring-loaded face seal could be used operating against the end face of the rotor. Should the transmission of power to the device be performed without any direct mechanical connection such as the example here depicted of an externally protruding drive shaft5, the requirement for a seal would be removed. Bearing20positioned close to the fluid inlet10is largely unaffected by heat build-up in other areas of the device. As shown, bearing20is of a type that can operate dry or wet depending on what operating conditions prevail, and may be of a type known as a steel backed PTFE lead lined composite bearing. Other forms of bearing types may be used however, and furthermore, rear housing member1may easily be modified to allow the addition of some form of sealing device at one end or both ends of this bearing20, and where such a bearing would preferably be self-lubricating.

Rear housing member1is provided with a circular register25at end face6on which one end26of housing sleeve member3is engaged, and similarly, front housing member2has a similar circular register27at end face7on which the opposite end28of housing sleeve member3is engaged. Sealant or some form of robust sealing device such as static seals disposed between these joining surfaces ensures on the one hand that the main chamber is not leaking fluid to the outer environment when the device is at rest, and on the other hand, suck air into the chamber due to the vacuum conditions prevailing when, the device is operational.

The rotor portions12,13as the rotor component is positioned in the housing members1,2,3with respect to end faces6,7with sufficient axial clearance to avoid contact. The exterior surface14on the rotor terminates at first and second planar end faces of the rotor. There therefore can be said to be clearance volumes at opposite ends of the rotor, and for this particular embodiment of the present invention, the clearance volume nearer to end face6is where the greater quantity of fluid arrives into the chamber via ports11.

Housing sleeve member3is provided with a threaded fluid exit connection30, also called the “exit or outlet”, and which, preferably, is disposed radially outwardly from said rotor portions12,13. Exit30is slightly displaced from the position shown in these drawings to avoid interference between connecting pipe-work and screws4. Although less preferable, the exit30could be positioned in the front housing members2instead of sleeve3.

Rotor sleeve portion13is provided with a plurality of openings in the form of nine circumferential rows of radial holes spaced about the rotor exterior surface14along the longitudinal axis of the rotor. As shown in this particular example, each row having eighteen such holes, the first row of openings nearer the inlet10denoted by reference numeral31where the last row of openings nearer the exit30denoted by reference numeral32. Although here described with eighteen holes per row, the actual number as well as their physical dimensions may be varied to suit the intended application. The use of so many holes can mean about 40% of the total rotor operational surface is exposed to openings. In practice, it is usual for more than one row of holes to be deployed on the rotor, and for reasons of compactness, it is preferable that first, third, fifth, seventh, ninth rows of holes out of phase by ten degrees from the intervening rows so that the rows can be spaced closer together across the axial length of the rotor than they would were they all phased together.

The inner shaft end40of rotor central portion12protrudes towards inlet10, and is provided with an entrance port denoted by reference numeral41leading to interior longitudinal passageway43. Longitudinal passageway43is tube-like in shape. Entrance port41is arranged to be in permanent communication with inlet10, and longitudinal passageway43forms part of the interior passageways or vessel disposed inside the rotatable unit. In this embodiment, plug42is fixed in position at entrance port41, plug42is provided with a relatively small throttle hole44which acts as an orifice and thereby allowing some fluid entering the device at inlet10to pass into the interior passageways. The interior passageways may also comprise as here shown a number of radial holes such as50,51which are located in the central portion12, all these holes communicating with longitudinal passageway43. Although only radial holes50,51are mentioned for the first and ninth row of openings31,32, intervening rows may also be provided with a respective radial hole as shown inFIG. 3. As shown, the central portion is provided with a series of annular fluid distribution grooves, and where each radial hole50,51may be arranged to meet a respective annular fluid distribution groove60,61, which is provided to allow fluid in longitudinal passageway43to flow through any respective hole50and groove60combination to reach all the individual openings in the associated row of openings31. As shown, all the other rows of openings are also provided with their own respective hole and groove combination, but it should be appreciated, depending on the intended application, that certain rows of openings may no-longer be required to be fluidly connected to longitudinal passageway43by such hole and groove combinations. Throttle44in plug42acts in restricting the amount of fluid from inlet10able to enter into longitudinal passageway43, as in this embodiment it is intended that the main or primary flow path through the device from inlet10to exit30travels via ports11to reach the annular clearance volume surrounding the exterior14of the rotor component. The fluid throttling conduit therefore prevents the larger quantity of fluid from travelling through the interior passageways in the rotor and reaching the annular passage by this route. Depending on the size of the throttle44in plug42, and other factors to do with speed of rotor rotation, temperature of fluid etc, the vacumm created “downstream” of the fluid throttling conduit is variable. For this rotor form, the relatively smaller amounts of fluid are able to reach the annular passage surrounding the exterior14of the rotor component via the interior passageways of the rotor reaches the openings, such as rows of openings31,32, by means of travelling through longitudinal passageway43and via respective hole and groove pairs,50,60and5161.

The interior passageways in the rotor being surrounded by the material composition of the rotor provide a heat transmitting surface to the fluid passing through these passageways. This acts to pre-heat the fluid before it arrives in the annular passage where the plurality of openings operating there are producing the main heating effect on the fluid.

To prime the device before starting, fluid admitted through inlet10is allowed to percolate into the interior of the central rotor portion12thereby flooding all the available interior space in the vessel, in particularly the longitudinal passageway43and interconnecting network of smaller passagways leading to the openings provided in the rotor sleeve portion. In this situation, fluid passing through fluid throttling conduit44fills up the interior passageways comprising the longitudinal passageway43, radial holes,50,51, grooves60,61as well as the various rows of openings31,32. Any air originally trapped in the device is thereby expelled and the device is now primed with fluid prior to the commencement of rotor rotation.

Then to operate the device, the prime mover is switched on in order to provide mechanical power in the form of driving torque and rotation to shaft5. On starting, fluid initially residing in the longitudinal passageway43and interconnecting network of smaller passageways, becomes rapidly expelled from the rotatable unit by centrifugal force, thus creating a partial vacuum condition in these regions, and depending on the size of throttle hole44used, this region remains under partial vacuum conditions as the amount of fluid entering via hole44is restricted.

Fluid such as cold water enters the device through inlet10, and for primary flow path, the fluid passes through ports11to that side of the rotor adjacent end face6from where the general disturbance by the rotating rotor propels the water radially outwards, bore15redirects the water into the annular passage between bore15and exterior surface14. Some heating of the water occurs due to the fluid being sheared between the static surface of the bore15and the moving surface14, but the majority of the heating of the water occurs due to being subjected to turbulent flow conditions caused by the many and varied negative pressure conditions in the regions neighbouring the multitude of openings31,32. In the case of the secondary flow path, the continuing quantity of water from inlet30passing through the throttle hole44in plug42enters into the interior vessel region of the rotor12,13where partial vacuum conditions are created, may cause this additional fluid to go through a rapid phase change to water vapour or steam. The two fluid steams meet in the annular clearance volume. The vacuum or partial vacuum condition thereby created in the interior of the rotor creates greater disturbances in the passing fluid flowing in the primary pathway between inlet10and exit30.

As an alternative to incorporating a single plug42with throttle hole44as shown inFIG. 3,FIGS. 5 to 8disclose a number of alternative interior locations within the rotatable unit for achieving fluid flow restriction for the secondary flow path from inlet10to exit30. InFIGS. 5 & 6, the entrance port41located in central element12leading to longitudinal passageway43does not contain a plug, hence the flow arriving at inlet10is able to enter the interior of the rotor portions12,13unrestricted. Each row of openings, such as first row31, is connected to the longitudinal passageway43by a radial hole70and its associated individual throttle71best seen inFIG. 6. Hence, here the fluid arriving into the longitudinal passageway43is propelled by centrifugal force through the radial hole70and throttle71before entering an individual opening31. As before, the rotatable unit12,13can be primed before operation is commenced as the fluid seep past the throttles71thereby filling the interior of the rotatable unit, and once operating, the pressure build up in the radial hole70below each throttle71causing an injection of a small quantity of fluid into the opening31. However, as the amount of fluid continuously being injected is small compared to the volume of each individual opening, the partial vacuum conditions in the opening during operation of the device remain largely unaffected.FIG. 7shows the addition of a groove75so that the flow through the throttles71may be evenly distributed to the complete row of openings31.FIG. 8discloses the use of a single radial hole76and throttle77for reasons of improved economy of manufacture, and where groove75allows the fluid to communicate with all openings31in that particular row of openings.

InFIG. 9, a solid plug80at the entrance port41in the central rotor portion12prevents the flow of fluid from inlet10directly into longitudinal passageway43. To prime the device and remove any air trapped in the interior of the rotor, fluid from the inlet10can pass through ports11to enter the annular clearance between rotor exterior surface14and bore15. As the fluid fills up this space, it can enter into the interior of the rotor portions12,13by passing through the openings, grooves, and radial holes, for instance,31,60,50to reach longitudinal passageway43. As soon as the rotatable unit12,13is rotating at high speed, centrifugal force causes that fluid in the interior to flow out from the longitudinal passageway through50,60,31to reach the annular working clearance between exterior14and bore15. A rapid evacuation or partial evacuation of the fluid in this internal region or vessel, thus may produce a good vacuum condition near to the openings to help provide a more rapid heating of the fluid passing through the annular working chamber.FIG. 11discloses the use of three radial holes82,83,84an alternative to the single radial hole50inFIG. 10.FIG. 12discloses the use of four bottom-ended holes85,86,87,88in central rotor portion12which act to capture fluid when the device is first primed.FIG. 13discloses a central rotor portion12with only a groove60to interconnect all openings in the first row31. The groove60helps in priming the device so that any air pockets present in certain of the openings can be expelled by the incoming fluid into the groove31from the openings31. Here as for the device ofFIG. 12, longitudinal passageway43is redundant.

FIG. 14discloses a modified rear housing member90where in contrast with the earlier rear housing member1, ports11are omitted. Therefore, the end face6of rear housing member90inFIG. 14does not include a port, and as such, there is not the earlier primary flow path. Here fluid entering the device at inlet10can now only reach the annular working clearance between rotor exterior surface14and bore15by first entering longitudinal passageway43. Entrance port41located at inner shaft end40of rotor central portion12carries a plug42with a throttle hole44. The device may be primed with fluid prior to starting by allowing fluid at inlet10to flood the interior of the rotor portions12,13as well as the annular clearance between exterior surface14and bore15. The fluid passes through the throttle hole44into the longitudinal passageway43and interconnecting network of smaller passages, radial hole50and groove60, leading to openings31on the rotor sleeve portion13. Although some fluid can enter the main chamber of the device by flowing past the running clearance between inner end40and surrounding bearing20, in practice and provided that the exit30is suitably restricted by an external flow valve (not shown), the cavitational effect produced in the liquid passing through the device can be quite pronounced.

FIG. 15also shows the modified rear housing member90together with a further form of modified rotor assembly comprising central rotor portion95and sleeve portion96. The sleeve portion is provided with several rows of openings such as openings97shown as the third row from inlet10. An inner shaft portion98of the central rotor portion95is provided with an entrance port99that leads to stepped longitudinal passageway100,101. In the position on inner shaft portion98next to bearing20and the end face91of the rotor, there are provided at least one radial passage92which communicates longitudinal passageway100with the axial clearance volume denoted by reference number93. Positioned further along in longitudinal passageway100, there is throttle plug104, and throttle plug104is fixed in position at this location such that a number of radial holes, such as hole105disposed in the central rotor portion95, are arranged to fluidly connect with the longitudinal passageways100,101on the “downstream” side of the throttle plug104. Fluid entering the device at inlet10and entering entrance port99passes in longitudinal passageways100to the point where the radial passages92divert the primary flow to the axial clearance volume93, to one end face91side of the rotor from where it is redirected by bore15to flow into the annular clearance volume between rotor exterior surface14and bore15. However, the throttle plug104provides a secondary flow path, and fluid passing through the throttle plug104, enters the interior of the rotor to be distributed via the radial holes, such as radial hole105, to the various rows of openings such as opening97.

DETAILED DESCRIPTION OF THE SECOND ILLUSTRATIVE EMBODIMENT OF THE INVENTION

In the second embodiment of the present invention depicted inFIGS. 17 & 18, the exit connection for the fluid denoted by reference numeral115is disposed in central housing member116is a location that is closer to the fluid inlet10than to seal21. As many components are identical to those described for the first embodiment and therefore do not require detailed description, for the sake of simplicity they carry the same reference numerals Whereas in the earlier embodiment, the direction in the flow of fluid from the inlet10to the exit30could be said to be in one direction from left to right, it is a feature of this as well as the third embodiment of the invention that the flow of fluid through the heat generator is arranged to double back on itself. One purpose of the fluid doubling back on itself is to obtain a better pre-heating of the initially cold fluid before it can enter the annular clearance volume; the second purpose is to attempt to protect the front housing elements2and especially the bearing22and seal21from the high temperatures generated by the heat generator. As a consequence, during operation of the heat generator of the second and third embodiments, the rear housing member remains relatively hot whereas the front housing member is relatively cooler.

As shown, the rotor120may be a one-piece component formed with an integral protruding shaft portion5. The rotor120is provided with four inclined passageways121,122,123,124connecting with longitudinal passageways126on the one hand, and on the other hand, opening on the end face127of the rotor120as best seen inFIG. 18. Between end face127of the rotor120and the wall or end face7of the front housing member2, is the volume space where the fluid is propelled radially outwardly by the revolving rotor120to be redirected by bore15to travel across the annular working clearance as defined by the radial clearance between the rotor exterior surface14and the confronting bore15. The relatively cold fluid entering the device at inlet10and the rotor120at entrance port130flows through passageways126,121-124to reach the volume space between revolving and static faces127,7and be redirected by bore5into annular clearance where a number of rows of bottom-ended holes132are positioned along the exterior surface14of the rotor120. The initially cold fluid as it flows through passageways126,121-124is pre-heated by the comparatively hot rotor unit120, while still significantly cold to keep seal21and bearing member22cool by absorbing further heat from the region adjacent to front housing member2. As the fluid moves through the annular fluid volume and interacts with the openings/depression zones, heat-generating cavitation conditions are experienced, and the heat energy imparted in the fluid is outputted from the device as the fluid exist the device at exit115.

FIG. 19 to 27disclose a number of alternative hole configuration for the rows of openings in the rotor120that can be used in place of openings132inFIG. 17. InFIG. 19, openings in the form of bottom-ended holes135are inclined along axis denoted as136with respect to the center of the rotor120denoted as numeral140. InFIG. 20, the inclination angle of the bottom-ended holes142along axis denoted as143is increased still further with respect to the center of the rotor140. The direction of rotor rotation is preferably counter-clockwise but for certain operational conditions, the rotational direction of the rotors120may be reversed. However depending on operating conditions, the ability to sweep back the openings can enhance the tendency for cavitation to occur, although not strictly analogous, swept wings in supersonic aircraft are a significant advantage during high speed flight.FIG. 21is depicts a series of bottom-ended holes144with a degree of bellmouthing145adjacent to the exterior surface14of the rotor120. The relative diameter of the bellmouth at the rotor exterior surface14exceeding the diameter closer to the axis of rotation of the rotor. The effect of bellmouthing increases the available surface area on the exterior of the rotor where cavitation of the fluid occurs without necessarily increasing the number of drilled holes.

With respect toFIGS. 22 to 24, the modified rotor depicted as120is an example of a more economic rotor configuration. This may be achieved specifically by reducing the amount of machining time required to form all the various surface detail on the rotor. As such, whereas earlier rotor embodiments for illustration purposes only were deployed with eighteen holes per row for each rotor, in this modified form of rotor, only four deep drilled holes are required per row, shown as holes150-153inFIG. 10. The depth of such holes may then exceed in distance to a greater dimension than the raduis dimension of the rotor. Preferably four further openings, these being shallow pockets154-157are also present spaced at forty-five degrees to one another and approximately equi-spaced between each of the deeper holes150-153. The next adjacent row of openings in shown inFIG. 23, and here deep holes are denoted as150i-153i, and shallow pockets154i-157i. Similarly, The next adjacent row of openings in shown inFIG. 24, and here deep holes are denoted as150ii-153iiand shallow pockets as154ii-157ii.

Note that all holes and shallow pockets in the second row of holes displayed inFIG. 23are indexed by forty-five degrees with respect to first and third rows of holes and shallow pockets. There may be further or fewer rows of holes if so desired in the configuration chosen for the rotor, this ultimately depending on the given application for the device and this flexibility is of course equally applicable to other embodiments of the present invention, as is the intercommunication with internal passageways and internal fluid throttling devices in the rotor.FIG. 25depicts a further possibility for the openings in the rotor120, in-particular whereby the depth of holes deployed in any typical row of holes can be of increasing depth as is here shown for holes160-163. Just as a vibrating tuning fork held over over a glass cylinder can cause the column of air inside the cylinder to resonate at the same frequency when the depth of the cylinder is of the appropriate length, the holes of varying depth in this rotor may more readily have the right combination of frequency, wave form and amplitude to cause a further excitation of the water molecules during the general disturbance experienced during cavitation.

FIGS. 26 & 27depict further modifications in the holes for rotor unit120, and in particular to exemplify that any set of holes in any particular row of holes may be partially or fully interconnected to form a continuous pathways for the transmission of shock waves, and thereby heighten the effect from shock waves during the operation of the device. By way of example,FIG. 26depicts rotor120having deep holes165-168which are interconnected by interconnecting passages170-173. Although as shown, such passages170-173are of reasonable size to ease the machining operation, they may also be sized much smaller so that they act as throttles to limit the amount of fluid able to transit from, for example, hole166to165or vice versa.FIG. 27is the rotor ofFIG. 26with the addition of shallow pockets175-178, and where pockets175-178are provided with interconnecting passages, here shown as interconnecting passages180-183.

As compared toFIG. 17, inFIG. 28, the rotor unit is comprises of a central portion190integral with protruding drive shaft5and a surrounding sleeve portion191which is preferably a heat shrink fit on central portion190. The sleeve portion is formed with several rows of openings such as opening denoted by reference numeral192. InFIG. 29, the central portion190is modified, and opening192is shown fluidly linked to longitudinal passageway126via, firstly circumferential groove193; secondly throttle195; and thirdly connecting radial hole194. The row of openings marked196are interconnected by a circumferential groove197and not directly linked to longitudinal passageway126.

DETAILED DESCRIPTION OF THE THIRD EMBODIMENT OF THE INVENTION

Whereas the last embodiment had the fluid arriving at the end of the rotor closest to the seal, for the third embodiment depicted inFIGS. 30 & 31, the fluid is arranged to arrive directly into the annular working clearance between rotor and surrounding housing. Rotatable component200is provided with an entrance port201leading to internal longitudinal passageway202. Passageway202connects with one or more radial passageways205which direct the fluid, entering at intake10, to the exterior peripheral surface14that lies radially inwards of bore15. Once fluid entering this annular clearance at the point where the radial passageways205opens at210on peripheral surface14, the fluid travels across a series of rows of holes denoted by reference numerals211-218before exiting the device in a heated condition at threaded exit connection115. The relatively cold fluid entering at axial port201picks up heat from the rotating component200during its transit to opening210on peripheral surface14, thereby pre-heating the fluid.

As compared toFIGS. 30 & 31, the device ofFIG. 32incorporates a fluid throttle218at the inner shaft end219of rotating unit220, the throttle having a central hole221to control the flow passing from inlet10to longitudinal passageway222. Fine tuning the flow of fluid through the device may be achieved by placing a variable flow control valve (not shown) external of the unit and “upstream” of the exit115to ensure that the annular working clearance remains sufficiently filled with fluid.FIGS. 33 & 34shows the positioning of three throttles230,231,232in the rotatable unit233in respective radial passageways235,236,237. Radial passageways235-237connect with longitudinal passageway240which is in turn is connected by port241to inlet10. Located on the circumference on the rotor between these throttle are a first array of openings242. In the device shown asFIGS. 35 & 36, fluid entering the device at inlet10passes from entrance port250provided in the central portion251of the rotatable unit to reach the internal longitudinal passageway252. The rotatable unit comprises a rotor sleeve portion253fixed to the central portion251, preferably by a heat shrink fit, and where the protruding drive shaft5is formed integral with central portion251. The primary flow pathway from longitudinal passageway252is via the three radial passageways256,257.258and their associated passages provided in central portion251denoted as passages260,261,262, best seen inFIG. 36, before reaching the annular working chamber. There are also provided a series of secondary flow pathways in the central portion251, and only the one nearest to exit115is described as the others are identical. The secondary pathway here comprises a radial hole270and throttle271located in central portion251, and a circumferential groove272connects the fluid entering the groove272via the throttle271to all the openings273in this particular last row of openings. The throttles provide a flow restriction in each the secondary flow pathway to ensure that only a metered amount of fluid is admitted into the respective row of openings.

Where used, the addition of a plurality of fluid throttling conduits is useful, at least for the purpose of priming the unit prior to starting. So long as the orifice size is suitably small in the throttle, dimensioned as a generally narrow hole, the steady amount of fluid continuously entering the working annular passage via such throttle(s) holes will be relatively small as compared to the primary flow path entering the annular passage. With a suitable size of orifice for the intended application, the vacuum conditions formed near to the surface of the rotor in the region of the openings are not compromised. Although as shown, the orifice size of hole in the throttle conduit is relatively small-bore drillings can serve for certain applications when a higher flow rate into the interior of the rotor can be tolerated. Although round holes have been described as the preferred cross-sectional shape for the orifice in a fluid throttling conduit, this term is intended to cover other shapes such as for example, throttle grooves.

As used herein, the term “fluid heating” contemplates the heating of either liquids or gases, although in practice the heating of liquids will be more commonly performed. In the context of heating liquids, it will be expressly understood that the heating device and method according to the invention include not only the generation of a hotter liquid, but also the phase transformation of the liquid into a gas. Therefore, the heat generating device and method as described are also steam generators, wherein the difference between raising the temperature of a liquid versus generating a vapor phase of the liquid may be controlled by the speed of the rotation of the rotor and the design of the cavitation-inducing surface irregularities.

In accordance with the patent statutes, I have described the principles of construction and operation of my invention, and while I have endeavoured to set forth the best embodiments thereof, I desire to have it understood that obvious changes may be made within the scope of the following claims without departing from the spirit of my invention.