FLUID FLOW APPARATUS

Abstract: This invention relates to a heat exchanger located in a wall (20, 21) and comprising a plurality of channels A and B. The channels A and B are formed so that rotation thereof causes air to be pumped into the channels along a first communication way defined by the channels A for relatively hotter air and along a second communication way defined by the channels B for relatively cooler air in contra flow. Heat is transferred across channel separating walls (3). The inertial force of rotation acts on temperature induced local density variations within the respective channels to rapidly take heated or cooled air from the boundary layer of the walls (3) resulting in bulk mixing with air in the respective channels.

Description: FOR THE PURPOSES OF INFORMATION ONLY Codes used to identify States party to the PCI on the fionl pages of pamphlets publishing international applications undei ihe PCI * . FLUID FLOW APPARATUS This invention relates to fluid flow apparatus wherein boundary layer fluid flow influences the function of the apparatus. In heat exchangers where heat from one fluid is exchanged with heat from another fluid via an impervious separating wall, a temperature gradient must exist across the wall. Furthermore, the heat must cross both the boundary layers of the fluids in contact with the wall, in which layers the velocity of the fluid relative to the wall tends to zero as the wall is approached. These boundary layers impede the flow of heat by restricting the heat flow to thermal conduction with the non-turbulent fluids. Elsewhere within the heat exchanger the heat transfer rates are increased by the action of turbulence causing fluid mixing. Part of the energy used in moving fluid through a heat exchanger is dissipated purposely in creating turbulence near to the separating walls so as to minimise the thickness of the boundary layer. However, power is lost in this pumping action and the boundary layer is never really destroyed. A known technique for reducing the boundary layer thickness is to drive the fluid through the heat exchanger at a velocity too high for streamline flow or to provide appendages, dimples or other structures close to the separating wall which increase turbulence. Similar problems are encountered in a catalytic chemical reactor wherein the rate at which reactant fluid reaches the active surface is severely restricted by the non-turbulent flow regimes of the boundary layer close to the catalyst surface. This stagnant surface flow regime is also a cause of fouling of the catalyst and any o er reactor surface. It is an object of the present invention to provide a 2 technique wherein the boundary layer itself is acted upon. According to one aspect to the present invention there is provided the use in a fluid containing apparatus of an artificial inertial force field to act on density variations in boundary layers of said fluid to cause flow thereof. According to another aspect of the present invention there is provided a method of producing fluid flow within a fluid containing apparatus, the method comprising the step of putting the fluid in an artificially accelerated frame of reference whereby the artificially generated inertial force of acceleration acts on density variations in said fluid to produce flow of the fluid. In a preferred embodiment of the present invention the inertial force acts on density variations in boundary layers of said fluid to case fluid flow thereat. Thus, the invention is particularly applicable to situations wherein heat exchange across the boundary layer needs to occur. According to a still further aspect of the present invention there is provided apparatus for producing fluid flow comprising a fluid containing portion and means for applying an artificial acceleration to said portion whereby the artificially generated inertial force of acceleration acts on density variations in said fluid to produce flow of the fluid. In this way, the inertial force of acceleration acts differentially on what may be thermally produced density gradients within the fluid to produce fluid flow. Preferably, the fluid containing portion has a selected surface and the inertial force acts on density variations in fluid boundary layers at said selected surface to cause fluid flow thereat. Thus, the apparatus applies particularly to the boundary layer that contains the non-turbulent flow regime and situations wherein heat exchange across the boundary layer needs to occur. The invention is effective since thermally produced density gradients become differential force gradients when accelerated (assuming a negative gradient for density against temperature) . Consequently, any slight variation in temperature within a boundary layer is translated to a force gradient which produces fluid flow. It will be apparent that the accelerating frame of reference can be provided by a continuous rotation or by an oscillation about a fixed point. Preferably, the apparatus has a further fluid containing portion, said selected surface providing a thermal contact between said portions whereby said inertial force acts on density variations in fluid boundary layers at said selected surface to cause fluid flow thereat. In this case, where heat can be transferred at the surface and the local temperature variations are acted upon differently by the force of the accelerating reference frame so that fluid flow occurs at the surface notwithstanding that the fluid at the surface is within the boundary layer. Away from the surface in the remainder of the fluid containing portions where temperature variations are small as a result of mixing, the forces are smaller. Thus, the majority of the energy dissipated by the inertial force is restricted to the boundary layer regions near the surface. Consequently, the apparatus can be applied to situations where it is desirable for heat to pass between the respective fluid portions. The effect of the force is to drive the fluid at a higher temperature (lower density) relative to the surrounding fluid in a direction opposite to that of the force thereby causing relative motion of the fluid within the boundary layer. This results in increased mixing in those regions of the fluid that have greatest temperature gradients, namely at the interface between the surface and the fluid where the bulk fluid velocity relative to the surface is zero. This mixing greatly reduces or substantially destroys the boundary layer so improving the mixing and the efficiency of the heat passage. In a preferred embodiment, the first mentioned fluid containing portion defines a generally cylindrical shape rotatable about the cylinder axis. This is a particularly convenient shape for manufacture and application of the inertial force. In a preferred embodiment of the present invention, said first mentioned portion comprises a plurality of axially aligned channel elements radially spaced from the axis. This too is simple and convenient to manufacture. The channel elements can then have heat exchanging elements for said selected surface to provide thermal contact with said further fluid containing portion. This construction further aids passage of heat between the respective fluid containing portions. Preferably, said further fluid containing portion is defined " by the region substantially inwards from the perimeter of the channel elements so that for example the second portion can effectively be open to air to produce a simple and effective way of passing heat to or from the air without the requirement of a physical structure for the further fluid containing portion. In an alterna e embodiment of the present invention, said further fluid containing portion comprises an inner cylindrically shaped vessel, and an outer cylindrically shaped vessel is coaxially provided therewith to define said first mentioned fluid containing portion between said vessels. This is particularly useful for passage of heat between liquid to liquid. In yet another embodiment for the apparatus, a plurality of walls are provided for rotation around an axis to define a plurality of closed channel elements as said first mentioned and further fluid containing portions with the walls defining said selected surface. This again provides a simple and convenient manufacture. Conveniently, selected ones of the elements define said first mentioned fluid containing portion and the remaining elements define said further fluid containing portion. Indeed, it is easier if alternate ones of said channel elements define said selected channel elements. Preferably, the channel elements have a predetermined length which may be greater than zero and less than the diameter of said cylindrical shape. A simple construction of the apparatus arises where the walls extend between coaxially provided inner and outer cylindrically shaped vessels. Such walls are preferably formed by folding of sheet material to define the plurality of channels. They can be formed by channel elements which are formed from substantially the same shaped channel pieces. These pieces may be stacked in a cylindrical shape to define said first mentioned and further fluid containing portions. The performance of the heat passage across the selected surface is improved if said channel elements are corrugated. In another alternate embodiment of the present invention, the walls are formed by a plurality of spaced axially located discs having means to interconnect intervening spaces to define said first mentioned and further fluid containing portions. Conveniently, the or each fluid containing portion incorporates a radial asymmetry to produce a pumping force, in use, along an axial direction. Thus, there can be no requirement to provide extra means to drive the fluid through the respective fluid containing portions. In use, the apparatus includes means to supply relatively cooler fluid to the further fluid containing portion and relatively hotter fluid to said first mentioned fluid containing portion. These can take the form of rotating sealed manifolds. To further enhance the performance of heat passage, the selected surface is provided with flute shapes or the like thereon. Preferably, said apparatus comprises a heat exchanger with said selected surface providing heat exchange between the first mentioned and further fluid containing portions. The general performance and efficiency of heat exchange achieved can be better than hitherto known heat exchangers. The movement of the fluid away from the selected surface renders the apparatus of the present invention particularly applicable to a heat exchanger. A further static heat exchanger may be included wherein fluid to the first mentioned heat exchanger also passes through the static heat exchanger. Alternately, said apparatus comprises a chemical reactor with said selected surface being provided with a catalytic surface. The movement of the fluid away from the selected surface renders the apparatus of the present invention particularly applicable to a chemical reactor. Conveniently, said selected surface is permeable to reactant to be catalysed. In this way, reactant can pass between the respective fluid containing portions so as to provide a supply of un-reacted material to the selected surface. The means for applying an artificial acceleration to said portion(s) to generate an artificial inertial force of acceleration preferably comprises means to rotate or oscillate said portion(s) . According to another aspect of the present invention there is provided apparatus for producing fluid flow comprising a plurality of walls for rotation around an axis to define a plurality of closed channel elements wherein the elements incorporate a radial asymmetry to produce a pumping force on the fluid, in use, along the axis. Such a construction functions to give an efficient pumping action. Examples of the present invention will now be described with reference to the accompanying drawings, in which:- Figure 1 illustrates the forces that act on a fluid volume element within an accelerating frame of reference, Figure 2 illustrates a sectional view of a heat exchanger embodying the present invention taken along the axial line II-II of figure 3, Figure 3 illustrates a cross-section of figure 2 taken along the line III-III, Figure 4 illustrates the view along the axis of another heat exchanger embodying the present invention, Figure 5 illustrates the view along the axis of another heat exchanger embodying the present invention, Figure 6 illustrates a sectional view of another heat exchanger embodying the present invention taken along the axis of rotation, Figure 7 illustrates a sectional view of the heat exchanger 8 shown in figure 6 adjacent the inside wall as mounted, Figure 8 illustrates a sectional view of the heat exchanger shown in figure 6 adjacent the outside wall as mounted, Figure 9 illustrates schematically the air flow through the heat exchanger channel elements A from inside to outside for bi-directional use, Figure 10 illustrates schematically the air flow through the heat exchanger channel elements B from outside to inside for bi-directional use. Figure 11 illustrates schematically the air flow through the heat exchanger channel elements B from inside to outside for uni-directional use, Figure 12 illustrates schematically the heat exchanger of figure 6 in combination with a static heat exchanger, Figure 13 illustrates a section along the axis of an embodiment of the present invention as applied to a chemical reactor. Common features within the drawings are identified by common reference numerals where appropriate. Referring to figure 1, a fluid volume element V lying on a circle 1 and within a frame of reference rotating about an axis 2 has an inertial force F acting thereon in response to local variations in density p(T) of the fluid, where the density is dependent on the temperature T of the fluid. The following differential equation applies to this situation:- dF/dV = d(p(T)) x (dv/dt)/dV where v is the local fluid velocity vector which varies in time. The action of the force F is to locally accelerate the fluid element to a radial velocity of v(r) . The velocity vector has three components, one angular v(0) , one axial v(z) , and one radial v(r) as shown in figure 1. Thus, cooler fluid having a relatively higher density will tend to move outwards from the axis 2. Where adjacent channels are provided in thermal contact and both are rotated about an axis, two separate paths can be followed in space by the fluid streams bringing heat to or taking heat from the thermal contact. One path is a spiral path, in which the fluid is given initial angular momentum, followed by a helical path in which the fluid has constant angular momentum. A similar path is followed by the second fluid stream but the two streams may be parallel or anti- parallel in adjacent channels. The vectors of angular velocity v(0) and axial velocity v(z) are orthogonal to the force F vector and so have zero product. This means that the force F can be made arbitrarily large without incurring additional viscous power losses from the velocity of the bulk fluid. Only the relatively small component of the fluid velocity v(r) in the radial direction caused by the force F has a finite vector product with the vector F. The majority of the energy dissipated by the action of the force F is therefore restricted to the region near the interface between the fluid streams. The effect of this force is to drive fluid at a higher temperature, relative to the surrounding fluid, in a direction opposite to that of the force thereby causing relative motion of the fluid adjacent to the interface. The action of the force F is to continuously destroy by fluid mixing any density variations in the fluid. Even with zero bulk fluid motion, the force F acts to destroy 10 the boundary layer at the interface with undiminished strength. This property contrasts fundamentally with the process of conventional fluid low apparatus where the thickness of the boundary layer increases as the bulk fluid motion decreases. The inertial force F acting on a volume element in a rotating frame of reference is directed therefore in the + or - radial direction. Thus, the orientation of the interface relative to the direction of the force F is important. Where the interface separates an inner relatively hotter fluid from an outer relatively cooler stream, the maximum effect is where the interface is perpendicular to the force. An intermediate effect is where the interface is parallel with the force separating two streams running parallel. By slanting elements in the latter case, it is possible to obtain some of the advantages of the former provided that the slant angle does not impair the self cleaning. This matter is discussed further hereinafter. The concept of the present invention can be applied to many different configurations. Referring to figures 2 and 3, a heat exchanger is located in a wall having an inner surface 20 and an outer surface 21. The heat exchanger comprises a plurality of elongate channels 8 which are closed along their length and are mounted in a cylindrically shaped housing 5. Separate channels are defined in this example by walls 3. The left ends (as viewed in figure 2) of alternate channels 8, labelled A in figure 3, have an end section 22 of the axially outer portion of the channel cut out to open exclusively to a radially outer manifold 6 which has one or more outlet grilles 9. The left ends (as viewed in figure 2) of alternate channels 8, labelled B in figure 3, have an axially inward corner or angle section 23 cut off to open to 11 a radially inner area portion 24 which opens to the outside of the wall by means of one or more grilles 25. The right end of the heat exchanger (as viewed in figure 2) is similar to the left end. In this case, the ends of alternate channels labelled A in figure 3 have an axially inward corner or angle section 23' cut off to open to a radially inward area portion 24' which opens to the inside of the wall between a front cover 26. The right ends of alternate channels, labelled B in figure 3, have an end section 22' of the axially outer portion of the channel cut our to open exclusively to a radially outer manifold 6' which has one or more grilles 9• . It will be apparent that the construction of the end manifolds channel ends can take many forms. Thus, a first communication way is formed along the channels A via region 24', manifold 6 and grilles 9. This is indicated by a dot and dash line in the figure. A second communication way is formed along the channels B via grilles 25, region 24, manifold 6• and grilles 9 ■ . This is indicated by a line of crosses in the figure. It will be apparent that the respective end manifolds are adapted to prevent leakage of air therebetween. Furthermore, it will be apparent that the flow of air through channels A and B do not cross and are kept separate on each side of the heat exchanger. The housing and channels A and B are mounted via radial spokes 11 to a motor 12 rotatably provided on a fixed mounting shaft 14. The end manifolds are connected to the housing 5 which is fixedly mounted via spokes 13 to the mounting shaft 14. A wall 27 prevents passage of air along the inner region bounded by the channels 8. Thus, when the motor 12 is actuated, the cylindrical housing comprising the channels A and B rotate about the axis 2 on which the shaft 14 is mounted. The end manifolds remain stationary but sealed by means of seals 7. 12 The channels A and B are formed so that the action of rotation causes air to be pumped into the channels along the respective communication ways described above. In operation, the housing channels 8 are rotated and relatively hotter air enters through the front cover 26 into the region 24* and passes along channels A to exit to the outside the wall through grilles 9. Relatively cooler air enters through grilles 25 to region 24 and passes along channels B in contra flow to exit through grilles 9' . At the surface of the walls 3 separating the channels A and B, heat from channel A is transferred or passed across the wall to channel B. In channel B this higher than average temperature air at the wall surface with a relatively lower density is driven inwards towards the axis 2. At the outer side of the wall in channel A, the air is cooled by conduction through the wall to the air in channel B. As this air cools, it becomes a lower than average temperature and hence higher than average density so that it is driven outwards from the axis 2. As the relatively hotter or cooler air is carried away from the wall during the process of heat transfer, air which has not been relatively heated or cooled in drawn to the wall surface. Consequently, by placing the fluid in an artificially accelerated frame of reference, the inertial force F acts on temperature induced local density variations to rapidly take heated or cooled air from the boundary layer of the wall 3 resulting in bulk mixing with air in the respective channels. Flutes (not shown) can be provided on the wall surface so as to enhance heat transfer rates. Consequently, enhanced transfer by the breakdown or reduction of the non-turbulent boundary region by the use of the inertially driven differential force is particularly important in attaining the efficient heat transfer described herein. The release of heat at the surface of wall 3 results in rapid removal of the heated air in channels B from the surface 13 through the action of the aforementioned inertial forces driving the fluid towards the axis 2 of rotation. This results in bulk mixing with the bulk fluid in the channels B and the flow of un-heated air to the wall surface. The bulk of the air in channels A is cooled or temperature controlled by conduction through the walls 3 to the relatively cooler air passing through channels B. In this embodiment, the surface of the walls are self cleaning because debris or the like which would normally case fouling are driven to the axially outer or inner surfaces of the channels 8 depending on their relative densities. Alternatively, a simple pumping action of the fluid can be produced by introducing an overall geometrical asymmetry in the radial direction between the respective ports of the channels A and B. The asymmetry is such that the air leaves the heat exchanger structure at a larger radius than it enters the structure. However, the angular momentum of the air as it passes through the heat exchanger is conserved. Hence, the axial length of the heat exchanger and so the thermal efficiency of the system can be increased indefinitely without effect on the angular momentum. The integration of the pump action also eliminates the fluid turbulence created at the interfaces between separate pumping elements and the heat exchange structure used in a conventional system. Eliminating this source of fluid turbulence increases the mechanical efficiency of mass transfer through the exchanger system and reduces the noise generated by turbulence in the fluids. By suitable selection of the material comprising the walls 3, a heat exchange effect can be produced between the aforementioned contra flows in channels A and B. The walls defining the channels A and B are preferably formed from thin films of plastics or metal with the channels uniformly distributed around the axis 2. 14 It will be apparent to a person skilled in the art that the formation of the adjacent channels A and B with the present invention can take many forms. For example, the channels A can be formed by mounting tubes in the intervening space between inner and outer skins with the remaining space defining channels B. Alternatively, the channels can be formed by making a series of folds in a sheet or foil of metal, paper of the like. The sheet is then inserted in the intervening space between the inner and outer skins with the radially outer end of each fold attached to the outer skin and the radially inner end of each fold attached to the inner skin. Thus, each fold defines a wall 3 between adjacent channels. The channels 8 can also take many forms of practical shape, for example they can be in honeycomb form as in a car radiator. Preferably, the channels have a corrugated form which corrugations are not too deep to impair the self cleaning. Moreover, with the embodiment as shown in figures 2 and 3, the walls 3 separating adjacent channels can be made from two slightly different tapered stamped plates which are stacked into a cylinder to form the heat exchanger, end ducts and pumping effect in a simple manner. The air inlets are angled with respect to the axis to give a larger cross- sectional area and both inlets and outlets can be strengthened by overlap of material. Directional control of the air flows within the channels formed by these plates can be achieved by moulding the plates or by inserts. Either internal or external rotor motors can be used. Alternatively, the channels walls can be identical in form and stacked around the axis 2. The channels can therefore be produced in a number of different ways essentially restricted by the ways that thin sheets or foils can be manipulated. They can be rolled, folded, twisted or left flat and can be deformed by pressing or the like. It is possible, amongst other ways, to have the walls defining the channels as planes running along the axis 2 and intersecting it, a series of discs aligned on the axis 15 perpendicular thereto with interconnection by means of holes in the discs which are open/sealed to alternate discs, or cylinders parallel to the axis. It will also be apparent to a person skilled in the art that as a result of the centrifugal forces, some form of outer sleeve may be required to hold the channels in place. In order to avoid any thermal shunting between the two end manifolds, a thermal barrier should be included. The aforementioned inertial force ensures that the boundary layer is substantially reduced or effectively destroyed leading to improved heat transfer between the air flows. Baffles can be introduced at the ends of the channels or within the end manifolds so as to provide a radial temperature gradient within each channel. In fact, the inertial force causes thermal differentiation of the air throughout the volume of the channels with the air of higher temperature or lower density moving in a direction opposite to the inertial force vector. This internal process of thermal differentiation is useful because it allows air inlets and outlets to the exchanger to be positioned so as to minimise mixing between air streams or volumes of significantly different temperature, an effect know as thermal shunting. It will be apparent to a person skilled in the art that the manifolds at each end can be adapted such that the heat exchanger acts as a one way fan. Indeed, with the present invention, the channels in the embodiment above can have a wide range of lengths down to almost zero length where the function is primarily as a bi-directional fan. The embodiment above, whilst described with reference to air to air heat exchange is not limited thereto. To apply the heat exchanger of the present invention to a liquid to air system, it is necessary to ensure retention or non-leakage of 16 the liquid and to allow for the large difference in density of the liquid relative to that of air. Relatively small diameter liquid seals are required and the heat exchange channels carrying the liquid can have a greatly reduced sectional area perpendicular to the direction of bulk liquid flow. An example is shown in figure 4. Relatively hotter liquid enters the heat exchanger 39 through an inlet port 40 lying on the axis 2 of the exchanger and connecting to a distributor 41. The distributer comprises a plurality of radial channels 42 connecting at their periphery tb respective axially parallel heat exchange channels 43. The other ends of the heat exchange channels 43 towards the port 40 are connected by further radial channels 44 to an outlet port 45. Each heat exchange channel has mounted thereon a large number of heat exchange fins 46 which may in reality comprise annular discs continuous around the axis 2 with each channel 43 intersecting the disc. The entire heat exchanger is rotated by means (not shown) and appropriate rotating seals 50 and 51 are provided respectively at the ports 40 and 45. In operation, the heat exchanger is rotated and hot liquid passes through the inlet port 40 to the distributer 41 and on to the exchange channels 43. There, heat is exchanged with air so that the relatively hotter air travels towards larger radii and eventually leaves the exchanger. The now cooler liquid at the outlet port 45 passes to a chamber 47 containing a rotating impeller 48 to increase the remaining angular momentum of the arriving liquid prior to exit through an outlet 49. Referring to figure 5, there is shown a liquid to liquid heat exchanger comprising an inner cylindrically shaped vessel 30, an intermediate cylindrically shaped vessel 61 and an outer cylindrically shaped vessel 31. At one end there is provided a manifold 62 having an inlet 63 for feeding relatively hotter liquid to the space 64 between the vessels 31 and 61. 17 This liquid leaves via an outlet 65 provided in a manifold 66 at the other end of the vessels. The manifold 66 includes a inlet 67 for cooler liquid to be fed to the space 68 between the vessels 30 and 61 and this liquid leaves via an outlet 69 provided in the other manifold 62. Appropriate seals 70 are provided for the manifolds. In operation, the vessels rotate about a common axis 2 by means not shown. The heat exchange occurs through the surface of vessel 61. To give angular momentum to the liquids entering at the inlets, the radial spaces of the vessels connecting to the spaces 64 and 68 include radial fins 71 which are fixed within the vessels. The improvement in heat transfer over a conventional static heat exchanger resulting from the inertial forces reduces as the temperature differences are reduced. Hence, the thermal performance of the above heat exchanger over a conventional system increases as the overall heat recovery efficiency decreases. This shifts the optimum design away from very high thermal efficiencies and makes it especially suitable for use in regions where there are large outside air temperature variations. Referring to figures 6 to 11 where components common to figure 2 and 3 bear the same reference numeral, there is shown a further embodiment of the present invention in which the heat exchanger described in figures 2 and 3 is adapted to operate with filtering and can be bi-directional or unidirectional. This embodiment is similar to figure 2 except that ducting is provided below the heat exchanger. As viewed from outside the wall surface 21 (Figure 8) , air enters via a grille 100 into a duct Y by means of suction (the fan effect) created by the rotation of the channels B. The air passes down duct Y to the inner side of the wall surface 20 where a connecting duct section W (Figure 6) 18 returns the air towards the outside again down a duct Z. The duct Z includes a filter material 101 to filter air passing therethrough. At the outside, a duct 102 is provided to connect to the duct Z to ensure that the air enter the region 24 for passage down channels B where it exits grilles 9•. As can be seen in figure 7, controls 103 are provided on the inside, which cover the end of channel Y. Air from the inside of the wall 20 enters via the inside of the heat exchanger and passes via region 24* , through channels A and out through the grilles 9. The passage of air from the inside to the outside is schematically shown by the solid line in figure 9 and the passage of air from the outside to the inside is schematically shown by the solid line in figure 10. Once again, heat is exchanged between the air in channels 8(A) and 8(B) . The control 103 includes a rotatable knob 107 connected to a flap 104 which opens a grille 106 at the inside lower surface of duct Z and closes the connecting duct W thereby isolating duct Y from duct Z. At the same time, a grille at the inside upper surface of duct Y opens and the grilles 9' are closed. In this way, a duct 105 connecting to manifold 6 » now connects to duct Y. Thus, in. this case the channels B function to suck air in through grille 106, along duct Z, accelerated along channels B and pass out to duct 105 and duct Y instead of out through grilles 9'. Consequently, channels B extract air in the same direction as that of channels A. The passage of air in this case is schematically shown by the solid lime in figure 11. It is possible to incorporate the heat exchanger of the present invention with a conventional static heat exchanger giving two fluid pumping actions or moderate thermal efficiency flanked by, say, a static parallel plate heat exchanger to boost thermal efficiency as required. Such a 19 construction is schematically shown in figure 12. The line of crossed represents the passage of air towards the inside of the wall 20, 21 and the dot dash line represents the passage of air towards the outside of the wall 20, 21. In each case the air passes through a static parallel plate heat exchanger 110. The concept of the present invention can be applied to many different configurations. For example, referring to figure 13, a catalytic reactor 83 comprises a closed outer cylindrically shaped vessel 84 mounted for rotation (by means not shown) about an axis 2. The inwardl facing surface of the vessel is coated with a catalyst 86. A coaxially mounted inner cylindrically shaped vessel 85 is mounted internally of the vessel 84 for rotation about the axis 2 (by means not shown) . At one end of the inner vessel 85 there is provided an inlet port 89 mounted on the axis and having an internal outlet port 90. The ports 89 and 90 are connected to open into the inner vessel 85 with the outlet port 90 having a cup-shaped member 91 to ensure that fluid from the inlet port does not travel straight to the outlet port. At the opposing end of the vessel 85 there is provided on the outer vessel 84 an outlet port 92 mounted on the axis 2 and having an internal inlet port 93. The port 93 is connected to open into the outer vessel 84 and the port 93 extends through the inner vessel 85 to open into the opposing end of the outer vessel 84. It will be appreciated that the respective ports are connected to the vessels 84 and 85 by means of rotating seals (not shown) . In operation, the reactor vessels 84 and 85 rotate and fluid reactants are supplied through port 93 and pass to the outer vessel 84 where they react at the surface of the catalyst 86. Heat is generated at the surface so that, as with the function of the heat exchanger above, this higher than 20 average temperature fluid with a relatively lower density is driven inwards towards the axis 2. At the outer surface of the inner vessel 85, the fluid is cooled by conduction through the vessel wall to a coolant supplied to the vessel 85 via the port 89. As the fluid cools in vessel 84, it becomes a lower than average temperature and hence higher than average density so that it is driven outwards from the axis 2 back towards the surface of the catalyst 86. Within the inner vessel 85, coolant from the port 89 is heated at the vessel wall by conduction and the heated coolant of lower than average density travels towards the axis 2 and is removed by the port 90 via the cup-shaped member 91. Reacted fluid then passed to the outlet port 92. Consequently, by placing the fluid in an artificially accelerated frame of reference, the inertial force F acts on temperature induced local density variations to rapidly take heated reactant fluid from the boundary layer of the active surface of the catalyst 86 to the boundary layer of the cooler surface of the inner vessel 85 resulting in bulk mixing with fluid in the outer vessel 84 and the flow of un- reacted fluid to the surface of the catalyst 86. Bulk reaction fluid is cooled or temperature controlled by conduction through the wall of the vessel 85. Flutes (not shown) can be provided on the inwardly facing surface of the vessel 84 which can also be coated with catalyst so as to enhance reaction rates. This advantage applies particularly since the transfer of heat to or from the fluid is the dominant mechanism for heat transfer at the catalyst surface. Consequently, enhanced transfer by the breakdown or reduction of the non-turbulent boundary region by the use of the inertially driven differential force is particularly important in attaining the efficient chemical reactor described herein. Thus, the chemical reactor above or a modified form thereof reacts to differences in temperature and, whether in heat 21 generating or heat consuming reactions, the reacted fluids containing the desired reaction products are carried away from the catalyst surface in the process of heat transfer, thus drawing un-reacted fluids to the catalyst surface. The heat exchanger embodiment of figures 2 and 3 can be adapted to function as a chemical reactor by coating both the internal walls of the channels 8 labelled A with a catalyst. Reactant fluid is then provided to the channels A and coolant is provided to the channels B. As regards the heat passage between the channels A and B, the function of such an apparatus when rotated is similar to that described with reference to figure 6. In this embodiment, the surface of the catalyst is self cleaning because products and debris which would normally case fouling are driven towards or away from the axis depending on their relative densities. It will be apparent that the manifold structures 6 and 6' can be adapted so that reactant fluid travels along one channel A and back along an adjacent channel A. In the same way, coolant fluid can be fed and drained from the same manifold. It will be apparent that the walls defining the channels 8 can be formed of a perforated wall which can be a tailored membrane or some other permeable material. Then, in use, a pressure differential is applied to ensure a higher pressure in the channels B relative to the channels A. Thus, as reactions progress, reactants added to the coolant pass from the channels B into channels A to enhance the reaction rate. It is apparent that a reverse pressure could be applied so that reaction products pass into the coolant, with the coolant being recirculated to attain optimum enrichment of the reaction products. It will be apparent that the present invention has many applications which have not been described and the invention is not limited to the two specific types of fluid flow 22 apparatus mentioned. Further modifications of and alternative embodiments of the present invention will be readily apparent to a person skilled in the art. For example, the principle can be employed in extractor fans, oil pumps and has many automotive applications. It will also be apparent to a person skilled in the art that some features described specifically with reference to one fluid flow apparatus can be adapted to other types of fluid flow apparatus.

Claims: 23 CLAIMS 1. The use in a fluid containing apparatus of an artificial inertial force field to act on density variations in boundary layers of said fluid to cause flow thereof. 2. A method of producing fluid flow within a fluid containing apparatus, the method comprising the step of putting the fluid in an artificially accelerated frame of reference whereby the artificially generated inertial force of acceleration acts on density variations in said fluid to produce flow of the fluid. 3. A method as claimed in claim 2 wherein the inertial force acts on density variations in boundary layers of said fluid to cause fluid flow thereat. 4. Apparatus for producing fluid flow comprising a fluid containing portion and means for applying an artificial acceleration to said portion whereby the artificially generated inertial force of acceleration acts on density variations in said fluid to produce flow of the fluid. 5. Apparatus as claimed in claim 4 wherein the fluid containing portion has a selected surface and the inertial force acts on density variations in fluid boundary layers at said selected surface to cause fluid flow thereat. 6. Apparatus as claimed in claim 5 having a further fluid containing portion, said selected surface providing a thermal contact between said portions whereby said inertial force acts on density variations in fluid boundary layers at said selected surface to cause fluid flow thereat. 7. Apparatus as claimed in claim 6 wherein the first mentioned fluid containing portion defines a generally cylindrical shape rotatable about the cylinder axis. 24 8. Apparatus as claimed in claim 7 wherein said first mentioned portion comprises a plurality of axially aligned channel elements radially spaced from the axis. 9. Apparatus as claimed in claim 8 wherein said channel elements have heat exchanging elements for said selected surface to provide thermal contact with said further fluid containing portion. 10. Apparatus as claimed in claim 9 wherein said further fluid containing portion is defined by the region substantially inwards from the perimeter of the channel elements. 11. Apparatus as claimed in claim 7 wherein said further fluid containing portion comprises an inner cylindrically shaped vessel, and an outer cylindrically shaped vessel is coaxially provided therewith to define said first mentioned fluid containing portion between said vessels. 12. Apparatus as claimed in claim 7 wherein a plurality of walls are provided for rotation around an axis to define a plurality of closed channel elements as said first mentioned and further fluid containing portions, with the walls defining said selected surface. 13. Apparatus as claimed in claim 12 wherein selected ones of the elements define said first mentioned fluid containing portion and the remaining elements define said further fluid containing portion. 14. Apparatus as claimed in claim 13 wherein alternate ones of said channel elements define said selected channel elements. 15. Apparatus as claimed in any one of claims 13 to 14 wherein said channel elements have a predetermined length. 25 16. Apparatus as claimed in claim 15 wherein said predetermined length is greater than zero and less than the diameter of said cylindrical shape. 17. Apparatus as claimed in any one of claims 12 to 16 wherein the walls extend between coaxially provided inner and outer cylindrically shaped vessels. 18. Apparatus as claimed in any one of claims 12 to 17 wherein said walls are formed by folding of sheet material to define the plurality of channels. 19. Apparatus as claimed in any one of claims 12 to 16 wherein said channels elements are formed from substantially the same shaped channel pieces. 20. Apparatus as claimed in claim 19 where said channel pieces are stacked in a cylindrical shape to define said first mentioned and further fluid containing portions. 21. Apparatus as claimed in any one of claims 12 or 20 wherein said channels are corrugated. 22. Apparatus as claimed in any one of claims 12 to 14 wherein said walls are formed by a plurality of spaced axially located discs having means to interconnect intervening spaces to define said first mentioned and further fluid containing portions. 23. Apparatus as claimed in any one of claims 4 to 22 wherein the or each fluid containing portion incorporates a radial asymmetry to produce a pumping force, in use, along an axial direction. 24. Apparatus as claimed in any one of claims 6 to 15 and 17 to 22 including means to supply relatively cooler fluid to the further fluid containing portion and relatively hotter 26 fluid to said first mentioned fluid containing portion. 25. Apparatus as claimed in claim 24 wherein the means to supply comprise rotating sealed manifolds. 26. Apparatus as claimed in any one of claims 6 to 25 wherein the selected surface is provided with flute shapes or the like thereon. 27. Apparatus as claimed in one of claims 6 to 26 wherein said apparatus comprises a heat exchanger with said selected surface providing heat exchange between the first mentioned and further fluid containing portions. 28. Apparatus as claimed in claim 27 including a further static heat exchanger wherein fluid to the first mentioned heat exchanger also passes through the static heat exchanger. 29. Apparatus as claimed in one of claims 6 to 26 wherein said apparatus comprises a chemical reactor with said selected surface being provided with a catalytic surface. 30. Apparatus as claimed in claim 29 wherein said selected surface is permeable to reactant to be catalysed. 31. Apparatus as claimed in any one of claims 4 to 30 wherein said means for applying an artificial acceleration to said portion(s) to generate an artificial inertial force of acceleration comprises means to rotate or oscillate said portion(s) . 32. Apparatus for producing fluid flow comprising a plurality of walls for rotation around an axis to define a plurality of closed channel elements wherein the elements incorporate a radial asymmetry to produce a pumping force on the fluid, in use, along the axis.

Inventors: RUSSELL FRANCIS MICHAEL, RUSSELL, FRANCIS, MICHAEL
Applicants: RUSSELL FRANCIS MICHAEL, RUSSELL, FRANCIS, MICHAEL
Application year: 1991
Main classification: B01J8
IPC codes: B01J8, F28D11, F28F13