Abstract:
An unheated, essential oil diffuser relies on a pressurized air stream to educt oil from a reservoir, followed by separators including separation chambers and an annular channel. The latter is a long channel having an aspect ratio (L/d) of from about 10 to about 120, for length L and thickness d. Thickness d is effective diameter, also known as hydraulic diameter (4 times c.s. area, divided by “wetted” or exposed perimeter), and may be from about 25 to about 100 thousandths of an inch (0.6 to 2.5 mm) across the thin passage, with a target range of from about 55 to 75 mils (0.7 to 1 mm). This geometry provides laminar flow at Reynolds number values less than a few hundred for virtually its complete distance of from under one inch (25 mm) to over three inches (76 mm).

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/265,820, filed Dec. 10, 2015, which is hereby incorporated by reference in its entirety. 
         [0002]    Additionally, this patent application hereby incorporates by reference U.S. Pat. No. 7,878,418 issued Feb. 1, 2011, U.S. Pat. No. 9,415,130 issued Aug. 16, 2016, U.S. patent application Ser. No. 14/850,789, filed Sep. 10, 2015, U.S. Provisional Patent Application Ser. No. 62/277,343, filed Jan. 11, 2016, and U.S. Provisional Patent Ser. No. 62/294,170, filed Feb. 11, 2016. 
     
    
     BACKGROUND 
       [0003]    Field of the Invention 
         [0004]    This invention relates to essential oils and, more particularly, to novel systems and methods for atomizing and diffusing them. 
         [0005]    Background Art 
         [0006]    Mechanisms exist for altering a closed environment such as a room or home with humidity. Likewise, mechanisms exist for removing humidity. Electronic and chemical mechanisms for destroying microbial sources of scents exist. Meanwhile, sprays, evaporators, wicks, candles, and so forth also exist to distribute volatile scents, essential oils, liquids bearing scents, and so forth. These may be introduced into breathing air, an atmosphere of a room, or any other enclosed space. 
         [0007]    Heating often destroys or at least changes the constitution of essential oils. Thus, it has limitations. However, the evaporation rates or atomization rates of essential oils are often insufficient to provide a controllable, sustainable, and sufficient amount of an essential oil into the atmosphere. Thus, wicks having no air movement (convection) mechanism often prove inadequate in all those respects. 
         [0008]    Meanwhile, mechanisms that seek to copy vaporizers and moisture atomizers often damage surrounding equipment, furniture, and other environs of a space being treated by essential oils. Moreover, the continuing “spitting” by atomizers of comparatively larger droplets not only causes damage to finishes on surrounding surfaces, but wastes a substantial fraction of the essential oil. 
         [0009]    Essential oils are concentrated sources of aromas or scents. Their extraction from source plants is sometimes complicated, and always comparatively expensive, based on the cost per unit volume of the essential oil. Therefore, colognes, other fragrancing systems, and the like often use high rates of diluents for essential oils. They also use synthetic oils and artificial scents that may not replicate the comforting, familiar, and natural essence of essential oils. 
         [0010]    By whatever mode, systems to distribute essential oils often waste an expensive commodity while damaging surroundings about their atomizers or other distribution systems. Thus, it would be an advance in the art to provide an apparatus and method for distributing essential oils in as small particles as possible, preferably vaporized, while protecting surrounding areas. It would be an advance to do so while retrieving and recycling for re-atomization or diffusion any droplets that are larger than those that may be sustained by effectively Brownian motion once discharged into surrounding air. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    In view of the foregoing, in accordance with the invention as embodied and broadly described herein, a method and apparatus are disclosed in one embodiment of the present invention as including a reservoir fitted with an extraction system for drawing out of the reservoir and feeding into a diffuser nozzle. The nozzle may operate as an eductor. In fact, in certain embodiments an eductor may include an injection nozzle feeding into a plenum which plenum feeds through a diffuser nozzle toward an ultimate discharge point or port. 
         [0012]    In certain embodiments, a system may include separation or drift chambers. For example, an initial separation chamber may actually be an evacuated space or vapor space near the top of a reservoir. This provides the advantage of the reservoir directly relying on contact accumulation, coalescence by contact between an atomized spray and the content of essential oil in the reservoir. 
         [0013]    Typically, an annulus of aspect ratio (length to width) of from 20:1 to 50:1 or greater may serve as a separator between this initial separation (drift) chamber, and other “downstream” separation (drift) chambers between the initial separation (drift) chamber and the ultimate discharge port. In various embodiments, lateral drift in laminar flow channels may separate out larger droplets for recycling. Changes of direction may also still serve as separation mechanisms. Thus, for example, the atomized flow composed of atomized essential oil and entraining air (air entraining those droplets and carrying them therewith) may pass as an atomized flow or simply flow through a circuitous route of passages. 
         [0014]    Separator mechanisms may coalesce out comparatively larger droplets as they either drift into or strike with impact against solid surfaces. Solid surfaces may be naturally occurring walls of conduits, the reservoir, and so forth. However, surfaces may also be made up of baffles simply placed within a conduit or path in order to cause changes of direction, and to receive and coalesce overly large droplets. “Larger” means having too much mass, or rather too great a mass-to-surface-area ratio to drift indefinitely in air. This may also be expressed as a volume-to-surface-area ratio. 
         [0015]    For example, a sphere has a volume. That volume is related to a third power of radius of the sphere. Thus, four thirds it multiplied by the radius to the third power equals the volume of a sphere having a radius of r. Meanwhile, the area of cross section (which controls air drag) is related to a second power or square of the radius. Surface area of the sphere is also related to the square of the radius. 
         [0016]    Thus, one can see that cross sectional area and surface area increase as the square of radius. Volume (proportional to mass and gravity force) increases as the cube. This means that as radius increases, mass, as well as momentum and gravity force, increase at a greater rate than areas (proportional to drag) increase. 
         [0017]    Conversely, this means that the decrease of radius decreases surface area as the square of radius, while decreasing volume as the cube of radius. Accordingly, there comes a point at which the cross sectional area controlling fluid drag of droplets in air is sufficiently large yet the mass and volume are sufficiently small, that a particle of such size may remain suspended indefinitely in air. That is, the drag forces resisting drift of the droplet downward with the force of gravity is sufficient to maintain indefinitely the drift of that droplet with the movement of air. Stated another way, the gravitational force is so miniscule as to be irrelevant to the time of drift. Gravity is unimportant. Drift can proceed effectively indefinitely. 
         [0018]    Evaporation is an entirely different mechanism. In evaporation, individual molecules of a liquid become individual molecules of vapor. Vapors then abide by Dalton&#39;s law of partial pressures and take their place with other surrounding vapors including air, constituted primarily by oxygen and nitrogen. Thus, evaporated portions of an essential oil have performed well their function of distributing into the surrounding air. 
         [0019]    Meanwhile, droplets sufficiently small to remain airborne substantially indefinitely, despite gravity, have also achieved their mission to distribute in air. Droplets too large, and therefore, too heavy, cannot be sustained in surrounding air against drift downward under the force of gravity. By drifting down these become the culprits in waste of essential oils and the damage to surrounding surfaces on which droplets land. 
         [0020]    Thus, in an apparatus and method in accordance with the invention, it has been found that various separators have proven effective to provide several key factors. For example, separation devices provide time. The time of passage or containment of a droplet within a separation chamber provides opportunity for comparatively larger droplets to drift toward any coalescing surface. By coalescing surface is meant a surface upon which overly large droplets may strike and coalesce with one another under the natural surface tension affinity that the essential oil has for itself. 
         [0021]    Also, the separation chambers have inlets and outlets offering changes of direction and cross section. Moreover, barriers will intercept “comparatively larger” particles by serving as coalescing surfaces. Barriers may also redirect flows, thereby encouraging striking thereof by overly large particles. 
         [0022]    Herein we will define overly large particles as particles that are larger, especially those more than an order of magnitude larger in diameter than self-sustaining (permanently drifting) droplets. Thus, permanently drifting droplets are defined as droplets of an atomized liquid that are sufficiently small that they will not drift downward, especially the height of a room within a day of eight to twenty four hours. Thus, the finest particles, defined as permanently drifting particles are those whose gravitational acceleration under the force of gravity is insufficient to drift down. 
         [0023]    Of interest also is any droplet that will not descend the height of a room within a day due to the resistance to drifting down by the fluid drag of the surrounding gases, such as room air. As a practical matter, droplets larger than these finest or permanently drifting particles are sufficiently small if they will drift with an airflow and leave with ventilation air. Often, air leaves a room in a matter of less than an hour. 
         [0024]    For example, the American Society of Heating, Refrigerating, and Air Conditioning Engineering (ASHRAE) defines standards for room ventilation. Finest particles will necessarily be drifting with the flow of air and will leave a room before they have substantial opportunity to drift to the floor. Moreover, because room air is exchanged so frequently, typically more than once per hour, particles that are an order of magnitude larger than the finest particles also fit within the definition of comparatively smaller particles. In other words, these stay aloft for sufficient time to be swept out with the circulation of room air. 
         [0025]    What is needed is a compact system to accomplish atomization and separation of the comparatively larger particles that can drift to the ground in less than an hour or less than an air exchange time. The size may vary with temperature and with the specific gravity (density compared to the density of water) of a particular essential oil. 
         [0026]    Thus, an apparatus and method in accordance with the invention may rely on a compactly packaged, annular separation chamber. They may include drift chambers also in the flow path. The annulus provides drift time and a smooth flow separation mechanism for comparatively larger particles to drift toward and coalesce against annulus surfaces. 
         [0027]    In one embodiment, a parallel eductor, which is effectively a coaxial eductor, operates to inject or atomize a plume of educted gas or vapor (e.g., air) starting as a jet entraining therewith a certain amount of an essential oil to be atomized. This jet, proceeding out of the jet nozzle or injection nozzle (which initiates and creates the jet), passes through a receptacle or well. The well is drawing the essential oil out of the reservoir, through a tube into that receptacle. 
         [0028]    The jet of air passing through the essential oil entrains a certain portion thereof, or entrains an essential oil at a rate and with sufficient energy to strip droplets from the surface of surrounding essential oil. It ejects those droplets with the jet through a diffuser nozzle. 
         [0029]    Of course, according to the laws of physics and engineering, droplets are generated in a variety of sizes. Initially, the largest of the comparatively larger droplets will not be able to make the turn required to reverse direction. Reversal is required in order to pass back out through the cap and a channel in the cap that exits the vapor space above the reservoir. 
         [0030]    The effect of this parallel or quasi co-axial injection is that the first coalescing surface that the comparatively larger droplets strike is not a surface of a solid at all. It is the upper surface of the supply of essential oil restored in the reservoir. This provides highly effective coalescence. It results in a comparatively large ongoing momentum transfer from comparatively larger droplets into the upper surface of the essential oil in the reservoir. 
         [0031]    Effectively, this may also entrain air into the upper surface, causing a certain amount of bubbling or foaming at the upper surface of the essential oil in the reservoir. 
         [0032]    Conservation of mass principles at work require that the air used for the jet in the eductor pass out of the vapor space in the reservoir. At least one channel is provided for that purpose. Meanwhile, there may exist a random action or trajectory of an overly large droplet toward any of the walls of the reservoir. Above the line or surface of the contained essential oil, this may result in those walls becoming coalescing surfaces. After coalescing overly large droplets, the walls continue draining them back into the essential oil contained in the reservoir. 
         [0033]    The full change of direction, about 180 degrees, from the injection direction toward the surface of the essential oil to the pathway out through the exit channel, represents a first separation process. It includes a direct-contact coalescence process. Some droplets may have direct contact with the content of the reservoir rather than coalescing with one another as each is smeared by impact against a coalescing surface. Thereafter a comparatively long annular channel relies on laminar flow, instead of turbulent flow to drift larger droplets toward its walls to coalesce and return to the reservoir. 
         [0034]    Applicant hereby incorporates by reference: U.S. patent application Ser. No. 12/247,755, filed Oct. 8, 2008, issued Feb. 1, 2011, as U.S. Pat. No. 7,878,418, U.S. Design patent application Ser. No. 29/401,480, filed Sep. 12, 2011, issued May 29, 2012, as U.S. Design Pat. No. D660,951; U.S. Design patent application Ser. No. 29/401,517, filed Sep. 12, 2011, issued Sep. 4, 2012, as U.S. Design Pat. No. D666,706; U.S. patent application Ser. No. 13/854,545, filed Apr. 1, 2013; U.S. patent application Ser. No. 14/260,520, filed Apr. 24, 2014; U.S. Design patent application Ser. No. 29/451,750, filed Apr. 8, 2013, U.S. Design patent application Ser. No. 29/465,421, filed Aug. 28, 213; U.S. Design patent application Ser. No. 29/465,424, filed Aug. 28, 2013; and U.S. patent application Ser. No. 14/850,789, filed Sep. 10, 2015. 
         [0035]    Each of these references, incorporated by reference herein in its entirety, discloses certain structures, components, controls, operating mechanisms, and designs for eduction and separation. In this application, Applicant need not, indeed cannot, reiterate all of the disclosure and illustrations contained therein. However, those references discuss various sizes and shapes of reservoirs, various types of caps and seals, various separation chambers, various striking surfaces or coalescing surfaces, and various paths and separation chambers. Those words are not necessarily used. Therefore, Applicant will hereby seek to define what is meant by these terms. 
         [0036]    By a reservoir is indicated a supply, or a container for holding a supply, of an aromatic substance, such as an essential oil. By a diffuser is meant a system for atomizing and distributed comparatively smaller particles, including finest particles as defined hereinabove, and suitably fine particles that are within about an order of magnitude of the same diameter or radius as finest particles. 
         [0037]    A jet is defined as in engineering fluid mechanics. A jet represents a flow of fluid having momentum, and passing through another fluid which may have the same or a different constitution. Thus, an air jet may pass through a surrounding oil. An air jet may pass through surrounding air. A significant feature of a jet is that it passes fluid having momentum through another fluid having a different specific momentum. Accordingly, momentum is exchanged between the environment and the jet, causing the jet to grow in size as a “plume.” A plume will decrease in velocity as the momentum is distributed among more actual material (mass). 
         [0038]    An eductor is a specific type of fluid handling mechanism. An eductor is a system in which a jet of a first constitution is injected into another fluid, typically of a different constitution. The momentum from the first jet is sufficient to cause the surrounding fluid entrained by the jet to continue as a plume of mixed constitution. 
         [0039]    Herein, an eductor mechanism is created in which a jet, the source of that jet, and the surrounding environment into which the jet is injected are passed through an aperture. Any portion of the jet that exceeds the diameter or maximum dimension across the nozzle cannot pass therethrough, and thereby must recirculate back to be re-entrained in the jet, or to some other disposition. 
         [0040]    A diffuser is in some respects an atomizer, but has the specific objective of producing finest fluid particles or droplets. Accordingly, a diffuser system includes not just an eductor but separation chambers, sometimes distinct separator structures. All are calculated to remove comparatively larger droplets, leaving only finest droplets and those within an about an order of magnitude thereof. Again, finest droplets or particles and comparatively larger particles have been defined hereinabove, in terms of their fluid dynamic behaviors. Those behaviors are defined by well established engineering equations. Therefore, all those equations are not repeated here. One may refer to textbooks and papers published on jets, atomization, fluid mechanics, two-phase flow, entrainment, plumes, and the like to obtain the details of the physics, the flow fields, the operational parameters, and governing equations for these phenomena. 
         [0041]    Vapor space in a reservoir is defined as a portion of the volume of a reservoir container that contains other than predominantly the liquid for which the reservoir exists. That is, the vapor region actually contains air, a certain amount of the evaporated essential oil, according to Dalton&#39;s law of partial pressure in chemistry, and a certain quantity of drifting droplets in transit. 
         [0042]    In certain embodiments of an apparatus and method in accordance with the invention, a reservoir may be fitted with an eductor injecting, through a diffuser nozzle, an entrainment jet containing both air, as the driving fluid, and atomized particles or droplets of the essential oil. 
         [0043]    Mass flow rate is equal to an area times the velocity of material passing through that cross sectional area, multiplied by a density of the material flowing. Volumetric flow rate is simply a velocity of the flow rate multiplied by the cross sectional area through which that flow passes. 
         [0044]    Whether looking at mass flow rate or volumetric flow rate, area is a controlling parameter. Increasing area, while keeping the volumetric flow rate constant, requires that the velocity slow down. Accordingly, in order to slow the velocity, area is increased. The result of a change in velocity is to permit more time for comparatively larger droplets to drift out of their entraining airflow toward any adjacent wall, baffle, or the like. 
         [0045]    Accordingly, it has been found that diffuser systems or diffusion system in accordance with the invention, operating with the structures and fluid mechanisms in accordance with the invention, provide three valuable benefits not found in prior art systems. First, comparatively larger droplets do not exit the discharge port and drift down upon surrounding surfaces. Second, this effectively diffuses and controls, without heating, the amount of the essential oil diffused in order to provide a specific level of scent that is pleasant and effectively as strong as desired (controlled), without being overly strong. 
         [0046]    Third, oil use required for a level of scent within a treated space has been shown to be much more efficient. That is, usage rates of less than half to a third of conventional systems result. Sometimes less than about one eighth to one tenth of conventional usage has resulted in systems in accordance with the invention. 
         [0047]    In summary, the treated space has the properly controlled amount of the essential oil to provide the aroma and ambiance desired. Compared to prior art systems, whose rate of use is much greater, the essential oils are more efficiently used. Furniture and other surfaces are not damaged, sticky, or unsightly from comparatively larger particles drifting down onto them. 
         [0048]    In various embodiments, a compact, integrated system may be placed within any arbitrary base or housing. It has been found that a reservoir may be fitted into virtually any décor. 
         [0049]    Meanwhile, only electrical power crosses to the system from the arbitrary base. This results in pleasant possibilities for design, along with compactness, uniformity, and convenience of integration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0050]    The foregoing features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which: 
           [0051]      FIG. 1  is an exploded, perspective view of one embodiment of a system and apparatus in accordance with the invention; 
           [0052]      FIG. 2  is a cross-section, elevation view thereof; 
           [0053]      FIG. 3  is a partially exploded, perspective view thereof, absent the reservoir; 
           [0054]      FIG. 4  is a perspective, assembled view thereof from the outlet side of the diffuser; 
           [0055]      FIG. 5  is a perspective view thereof from the air inlet side thereof; 
           [0056]      FIG. 6  is a lower quarter perspective view thereof from the outlet side thereof; 
           [0057]      FIG. 7  is a lower quarter perspective view thereof from the air intake side thereof; 
           [0058]      FIG. 8  is a front elevation view thereof; 
           [0059]      FIG. 9  is a right side elevation view thereof; 
           [0060]      FIG. 10  is a left side elevation view thereof; 
           [0061]      FIG. 11  is a rear elevation view thereof; 
           [0062]      FIG. 12  is a top plan view thereof; 
           [0063]      FIG. 13  is a bottom plan view thereof; 
           [0064]      FIG. 14  is a schematic diagram illustrating a velocity profile of fluid operating in a separator passage in a system in accordance with the invention; 
           [0065]      FIG. 15  is an interpretive, schematic diagram thereof; 
           [0066]      FIG. 16  is a chart identifying controlling equations for flow in the separation passage; 
           [0067]      FIG. 17  is an exploded schematic diagram illustrating various alternative bases or holders for containing, hiding, or both, a diffuser in accordance with the invention; 
           [0068]      FIG. 18  is an exploded, perspective view of an alternative embodiment of a system in accordance with the invention; 
           [0069]      FIG. 19  is a side, elevation, cross-sectional view thereof in an assembled configuration; 
           [0070]      FIG. 20  is an upper, frontal perspective view thereof; 
           [0071]      FIG. 21  is a upper, rear perspective view thereof; 
           [0072]      FIG. 22  is a lower, frontal perspective view thereof; 
           [0073]      FIG. 23  is a lower, rear perspective view thereof; 
           [0074]      FIG. 24  is a front elevation view thereof; 
           [0075]      FIG. 25  is a right side elevation view thereof; 
           [0076]      FIG. 26  is a left side elevation view thereof; 
           [0077]      FIG. 27  is a rear elevation view thereof; 
           [0078]      FIG. 28  is a top plan view thereof; and 
           [0079]      FIG. 29  is a bottom plan view thereof. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0080]    It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
         [0081]    Referring to  FIG. 1  and  FIG. 18 , while referring generally to  FIGS. 1 through 29 , details of alternative embodiments of an apparatus and method in accordance with the invention are illustrated. In general, what applies to  FIGS. 1 through 17  also applies to  FIGS. 18 through 29 . Thus, the embodiment of  FIGS. 1 through 13  is one, concentric, annular diffuser. In contrast, the embodiment of  FIGS. 18 through 29  is an alternative arrangement in which the sleeve  16  containing the drive  18  (the motor and pump system) is eccentrically mounted in order to increase the effective diameter (hydraulic diameter) of the passage  50  exiting the system toward the cap  80  and exit port  54 . In that embodiment a channel has also been made inside the wall  86 . Thus, most details of the embodiment of  FIGS. 1 through 13  apply equally to the embodiment of  FIGS. 18 through 29 . Accordingly, all references to general principals and structures of either embodiment apply to each embodiment. 
         [0082]    Referring to  FIGS. 1 through 3, and 18-19  while continuing to refer generally to  FIGS. 1 through 29 , a system  10  in accordance with the invention may operate with a reservoir  12 . In some embodiments, the reservoir  12  may be included as part of the system  10 . In other embodiments, a system  10  may be adaptable to a variety of reservoirs  12 , none of which need be an integral part of the system. 
         [0083]    One reason for this is that reservoirs  12  may be standardized to a certain extent. Accordingly, various reservoirs  12  representing various brands of suppliers of the contents thereof may be manufactured in a variety of sizes, shapes, and so forth. Typically, a reservoir  12  will be adaptable to the system  10  regardless of the shape of the reservoir  12 . At the very least, an adaptor may serve as an interface between a reservoir  12  and the remainder of a system  10 . Thus, in a sense, the system  10  may act as a cap  10  on the reservoir  12 . 
         [0084]    In a system  10  in accordance with the invention, the system  10  may include several principal components, subsystems, portions, or regions. In the illustrated embodiment, a reservoir  12  connects to a housing  14 . The housing  14  also receives inside of it, a sleeve  16 , sometimes referred to as a motor sleeve  16  or a drive sleeve  16 . Inside the sleeve  16  fits a drive  18  or drive system  18 . It may be proper to refer to the drive  18  as the pump  18 , the motor  18 , the motive system  18 , or the like. 
         [0085]    The principal function of the drive  18  is to provide a flow of pressurized air. The drive  18  is connected to provide a flow of pressurized air to an eductor  20 . A system of routes or passages is configured throughout the interior of the housing  14 . Initially, air is drawn from the surrounding environment. Ultimately, a flow is discharged from the housing  14 , adding a scent to the surrounding environment. 
         [0086]    The initial intake of air or incoming flow is charged with comparatively very small particles of an essential oil or the like. These particles are then discharged in a flow of air into the surrounding environment. The scent may provide aromatherapy, mood scent, or other effects as a result of the scent of the particle introduced. 
         [0087]    Referring to  FIGS. 2 and 19 , while continuing to refer generally to  FIGS. 1 through 29 , the inlet port  24  connects to an inlet chamber  26 . The flow of air, initially untreated, and then ultimately carrying a scent begins its entry into the system  10  through an inlet port  24 . From the inlet port  24 , air next passes into an inlet chamber  26 . The inlet chamber  26  may be provided with a filter, filter medium, or the like. Such a filter medium may fill the entire inlet chamber  26 , or merely a portion thereof. In some embodiments, the filter medium may simply act as a gatekeeper against dust or other pollutants undesirable to be flowing through the system  10 . 
         [0088]    To arrive at the point of receiving an essential oil or other content of the reservoir  12 , the flow of air in this particular example embodiment must pass from the inlet chamber to a transfer chamber  28 . The transfer chamber  28  provides a region  28  that can align with a perforation  30  or transition passage  30  in order to access a plenum  32 . The plenum  32  here is seen to extend across the housing  14 . The plenum  32  supplies through one or more openings the incoming flow of air into a cooling passage  34 . The passage  34  may be an annulus, multiple channels, or the like. 
         [0089]    One will note that the cooling passage  34  or passages  34  may run effectively vertically or substantially vertically between the sleeve  16  and the drive  18 . Accordingly, the cooling passage  34  passes a continuing flow of ambient air around the outside surfaces of the drive  18 . Thus, the cooling passage  34  provides a certain degree of cooling to the drive  18 . 
         [0090]    The drive  18  includes electrical equipment and the use of electrical power. The drive  18  benefits substantially from the cooling effect of incoming air that can receive rejected heat. Rejected heat is a term of art in thermal engineering and is used here as such. The flow will continually absorb waste heat discharged or rejected by the drive  18 , and carry that heat away. Thus, the enclosure by the sleeve  16  of the drive  18  still provides for continuing cooling by a continuing stream of outside or ambient air passing the drive  18 . 
         [0091]    From the cooling passage  34 , the air is eventually drawn into a portion of the drive  18  pumping that air into a plenum  36 . The plenum  36  now contains pressurized air pressurized substantially above ambient pressures. 
         [0092]    For example, air at ambient pressure is drawn by a reduction of that pressure, caused by the drive  18 . Thus, pressure is comparatively higher in the ambient than in the inlet chamber  26 . Pressure is higher in the inlet chamber than the transfer chamber  28 . Pressure is higher in the transfer chamber  28  than in the transition chamber  30  or the perforation  30 . Meanwhile, air pressure in the plenum  32  is higher than pressure in the cooling passage  34 . Pressure drops throughout the passage and through the cooling passage  34 . Pressure continues to drop until the pump portion of the drive  18  suddenly increases that pressure. Upon pumping, pressure rises in the plenum  36  relative to the other passages  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36 . 
         [0093]    From the plenum  36 , a nozzle opening  38  passages a comparatively smaller cross-sectional area of air at a comparatively much higher velocity than that air has experienced prior thereto. In the environment, the air is substantially quiescent. Whatever air movement there may be is comparatively small. Depending upon the area or cross-sectional area in each of the passages  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36 , the velocity of the air will change. At the nozzle  42 , the most restrictive (smallest) area results in a significant increase in velocity. 
         [0094]    As a practical mater, the mass flow rate of air through any passage  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36 ,  38  is equal to the density, times the cross-sectional area, times the velocity. Accordingly, at a mass flow rate that must be constant throughout, any increase of area along its path results in a decrease of velocity. Conversely, every decrease in area results in a proportional increase in velocity. Slight variations of density may occur, but are not significant. 
         [0095]    The nozzle passage  38  injects high speed air into an eductor chamber  40 . The eductor chamber  40  is extremely significant. The eductor chamber  40  receives the air from the nozzle  38 . However, the eductor chamber  40  also permits “eduction” of surrounding air. Eduction is a process of momentum transfer. From a central jet, representing the air exiting the nozzle  38 , the eductor chamber  40  provides a location wherein surrounding air within the eduction chamber  40  may be drawn in by the jet to be entrained in the jet. Thus, a jet exiting the nozzle  38  increases in size, and decreases in maximum velocity as it draws in surrounding air by eduction (direct momentum exchange) or entrainment. 
         [0096]    As a result of this eduction or entrainment, a reduced pressure surrounding the jet out of the nozzle  38  exists within the eduction chamber. Accordingly, the content  56  or oil  56  from the reservoir  12  is drawn into the eduction chamber  40 . 
         [0097]    Ultimately, the pressure difference between the eductor chamber  40  and a drift chamber  44  causes the spray to pass through a spray nozzle  42 . This spray nozzle  42  or eductor nozzle  42  stands in contrast to the air nozzle  38 . Only air passes through the nozzle  38 . In the eductor chamber  40 , surrounding residual air and the content  56  or essential oil  56  from the reservoir  12  mix together. The drift chamber  44  operates at an even lower pressure, thus the comparatively higher pressure in the eductor chamber  40  drives a spray in two phases (liquid and gas) made up of the oil  56  or other content  56  in comparatively small droplets or particles entrained within the air injected by the air nozzle  38  into the eductor chamber  40 . 
         [0098]    The spray ejected by the spray nozzle  42  or eductor nozzle  42  enters the drift chamber  44  in a downward, vertical direction. This is by design. By injecting downward, the nozzle  42  encourages comparatively larger particles that are sufficiently large in mass (and therefor in weight) that are incapable of remaining entrained in the air flow to continue down through the neck  46  of the reservoir  12 . 
         [0099]    In fact, the neck  46  or neck passage  46  continues into a vapor space  48  near the top of the reservoir  12 . Inasmuch as the vapor space  48  provides access to the oil  56 , comparatively larger droplets may drift down into the reservoir  12  to be captured by the oil  56 . Herein, oil  56  simply means the content  56  of the reservoir  12 . In some embodiments, the content  56  may be exclusively oil. In others, the oil  56  may be dissolved by a solvent such as alcohol or water. In some embodiments, multiple types of oils  56  may make up the content  56 . 
         [0100]    In order to exit the vapor space  48 , any air and entrained droplets must pass into an annulus  50  formed between the housing  14  and the sleeve  16 . In some regards, the annulus  50  provides additional cooling and isolation of the drive  18 . For example, the drive  18  is contained within the sleeve  16 . The sleeve  16  and drive  18  provide the cooling passage  34  of incoming air serving to cool the drive  18 . 
         [0101]    Moreover, the annulus  50  passing back up between the housing  14  and the sleeve  16  provides an additional layer of cooling and isolation of the drive system  18  and the sleeve  16  from the outside environment. Thus, heat from the drive  18  may continue to be carried away by the flow through the annulus  50 . The annulus  50  may be thought of as the passage  50  between the housing  14  and the sleeve  16 . Also, it is proper to speak of the annulus as the portions of the sleeve  16  and drive  18  that form a passage  50  or annulus  50 . For example, the annulus need not be entirely continuous about its circumference. 
         [0102]    Eventually, flow must pass from the annulus  50  out through a final drift chamber  52  or transition chamber  52 . The term drift chamber  52  refers to the fact that a two-phase flow necessarily includes both a vapor or gas and an entrained second phase (liquid here). The particles of the second phase are at liberty to drift. If they are sufficiently small, then the fluid drag imposed by the air (gas) on the second phase (e.g., oil) will be greater than the effect of gravity or the effect of momentum (due to velocity) of such a particle. 
         [0103]    Accordingly, sudden changes of direction, sudden changes of cross-sectional area, and the like will result in the need for a particle to change speed, direction, or both. Otherwise it may be thrown against a solid surface and splatter, or coalesce, or do some of both. Thus, in a drift chamber, generally, changes of direction result in particles of the oil  56  striking a wall, and thereby being either comminuted into smaller particles or coalesced against the wall, to flow back down into the reservoir  12 . By either mode, only those particles that are sufficiently small to change direction and speed rapidly enough to remain entrained within the air can be carried on to exit the housing  14 . All other droplets will eventually find their way back to the reservoir  12 . 
         [0104]    Exiting the annulus  50 , the flow passes through the final drift chamber  52  and ultimately an exit passage  54 . As explained, multiple drift chambers  44 ,  52 , as well as the drift passage  50  that is the annulus  50 , provide the opportunity for comparatively larger droplets to drift out of the flow. Those drifting out may shatter. All particles that cannot remain entrained must re-shatter or else coalesce against surrounding solid surfaces. This effectively filters or sorts the particles, thereby leaving only the comparatively smallest to exit out of the exit passage  54  into the surrounding environment. 
         [0105]    In the second phase (liquid) material, the content  56  or oil  56  in the reservoir  12  is drawn into a siphon tube  58 . The tube  58  extends below the surface  60  or liquid levels  60  of the content  56  in the reservoir  12 . The tube  58  here illustrated must necessarily pass up through the neck  62  of the reservoir  12  into the eductor chamber  40 . In the eductor chamber  40 , the comparatively high speed air blasting from the nozzle  38  fractures the flow of oil  56  into droplets entrained by the air flow and injected through the eductor nozzle  42  into the drift chamber  44 . 
         [0106]    The reservoir  12  may be connected to the housing  14  by threads  64  on the outer surface of the neck  62  of the reservoir  12 . A seal  66  between the neck  62  and the housing  14  may be both liquid tight and air tight. 
         [0107]    In general, a reservoir  12 , and more particularly, the threads  64  and neck  62  of the reservoir  12  may be received into a receiver  68 . The receiver  68  may be thought of as a receiver portion  68  of the housing  14 . In general, the body  70  of the housing  14  includes the barrel portion  72  that operates as the bulk of its containment. The receiver  68  necks down to a comparatively smaller diameter in order to fit the threads  64  and neck  62  of the reservoir  12 . Meanwhile, ribs  74  may be added for one of several reasons. Typically, the ribs  74  will provide additional strength, and, more importantly, stiffness stabilizing the body  70  or the shape of the body  70 . Thus, less material is required in the body  70  if the ribs  74  are spaced periodically to provide increased stiffness and strength. 
         [0108]    Opposite the receiver  68  at the bottom end of the body  70  is the collar  76 . The collar  76  is very much a business end  76  of the body  70  of the housing  14 . 
         [0109]    For example, an inlet lobe  78   a  accommodates the inlet chamber  26 . In other words, the inlet lobe  78   a  effectively has the inlet chamber  26  formed therein. Meanwhile, an outlet lobe  78   b  provides space for the exit passage  54  to pass, or otherwise connect to the annulus  50  or annular separator  50 . 
         [0110]    A cap  80  is the complement to the body  70 , sealing the body  70  to form the overall housing  14 . The cap  80  is fitted to the collar  76 . In fact, the collar  76  is provided with relief spaces  82  or sockets  82 . Those sockets  82  receive and register portions of the sleeve  16  fitted thereto. 
         [0111]    Similarly, at the opposite end of the body  70 , away from the cap  80  on the collar  76 , threads  84  match the threads  64  on the reservoir  12 . Again, the seal  66   a  serves to seal the neck  62  of the reservoir  12  against the receiver  68  of the housing  14 . Various other seals  66  are seen throughout the system  10 . 
         [0112]    The wall  86  of the body  70  extends along the receiver  68  and the barrels  72 . The wall  86  becomes somewhat more complex as it extends to form the collar  76 . 
         [0113]    An outlet  88  or aperture  88  formed in the cap  80  permits passage of scented air or a flow of scented air from the system  10  into the environment. The penetration  88  or aperture  88  in the cap  80  permits that passage. Thus, substantially all air into the system  10  must enter through the inlet port  24  in the collar  76  of the body  70  of the housing  14 . Substantially all fluid, meaning entrained particles and their entraining air will pass out of the system  10  by way of the outlet  88  or aperture  88  in the cap  80  sealing the system  10 . Any droplets coalescing against solid surfaces flow back to the reservoir  12 . 
         [0114]    Referring to  FIG. 3 , but also specifically referring to  FIGS. 1 through 3 , and continuing to refer generally to  FIGS. 1 through 29 , the body  90  of the sleeve  16  has some features in common with the body  70  of the housing  14 . For example, the body  90  of the sleeve  16  is provided with ears  91  or tabs  91 . These tabs  91  or ears  91  act as anchors  91  to register and secure the body  90  into the collar  76  and body  70  of the housing  14 . Specifically, the ears  91  are adapted to fit within the relief spaces  82  or sockets  82 . Fasteners then pass through the tabs  91  to seat in the sockets  82  of the collar  76 . 
         [0115]    An adapter  92  operates as a receiver  92  for the siphon tube  58 . Typically, an interference fit provides a fluid seal between the siphon tube  58  and the receiver  92 , which acts as an adapter  92  into the eductor chamber  40 . One may think of the eductor  20  as constituting a portion of the sleeve  16 . For example, a sleeve  16  seals against the drive  18  by a seal  66   b  (see  FIG. 2 ). That seal  66   b  connects the passage of air through the drive  18  and into the plenum  36 . 
         [0116]    The plenum  36 , injecting through the nozzle  38  a jet of air, sends that jet of air into an eductor chamber  40 . The eductor chamber  40 , itself, is formed as in interior portion within a well  94  at the lower end of the sleeve  16 . Thus, the drive  18  seals  66   b  against the well  94  of the sleeve  16 . This seals the drive  18  also against any entry of the scented air flow passing from the drift chamber  44  into the annulus  50 . 
         [0117]    The well  94  effectively terminates the bottom end of the barrel  96  of the body  90  of the sleeve  16 . Since the wall  98  of the barrel  96  operates as one wall  98  of the annulus  50 , one can see that the wall  86  of the barrel  72  of the body  70  of the housing  14  forms the other wall  86  of the annulus  50 . 
         [0118]    All of this geometry simply shows the significance and benefit of the vertical integration of the essentially concentric drive  18 , sleeve  16 , housing  14 , and reservoir  12 . The result is such a compact structure that is not only self contained, but contains sealed passages and self cooling by the incoming air. 
         [0119]    The effect of isolation by various seals  66  and the various walls  86 ,  98  of the system  10  provides additional sound proofing to render the system  10  more quiet, efficient, self cooling, and integrated into a smaller envelope than heretofore available. Here, envelope refers to the overall outer geometric volume, and its dimensions. Thus, here, the envelope is comparatively tall and comparatively narrow, with the system  10  comprised of effectively concentrically, vertically stacked components  12 ,  14 ,  16 ,  18 ,  20 . 
         [0120]    Just as the cap  80  fits the collar  76  to seal the body  70 , forming a housing  14 , the sleeve  16  has a cap  100 . The cap  100  seals against the drive  18  by the seal  66   c . The seal  66   d  effectively fits between the floor  104  of the cap  100  and an upper surface of the drive  18 . Meanwhile, an outer wall  102  bounds or surrounds the cap  100 , and fits the cap  100  inside the housing cap  80 . Thus, the wall  102  of the drive cap  100  fits within the wall  87  of the housing cap  80 . 
         [0121]    In the illustrated embodiment, the cap  100  also includes an inlet lobe  106   a  and outlet lobe  106   b . These lobes  106   a ,  106   b  serve to close off the inlet lobe  78   a  and outlet lobe  78   b  of the housing  14 . However, a significant difference between the lobe  106   a  and the lobe  106   b  is that the lobe  106   b  contains a conduit  108  or chimney  108  that effectively contains the exit passage  44 . That is, in some respect the conduit  108  is the exit passage  54 . However, in another way of speaking, the exit passage  54  is the cavity or open space within the conduit  108  or chimney  108 . Thus, one sees that a seal  66   e  about the conduit  108   a  seals the conduit  108  against the passage  109  in the collar  76  of the body  70  of the housing  14 . Thus, the final drift chamber  52  is sealed in connection with the exit passage  54  by the seal  66   e  therebetween. 
         [0122]    A controller  110  or control module  110  may be fabricated as, or on, a circuit board  110  with various components. In the illustrated embodiment, the control module  110  fits within the wall  102  or rim  102  of the drive cap  100 . A cover portion  112  fits within the inlet lobe  106   a  to close off the inlet passage  26  or inlet chamber  26 . In some embodiments, the inlet lobe  106   a  may also serve to seal off the inlet chamber  26 . 
         [0123]    However, in the illustrated embodiment, a perforation  30  through the floor  104  of the sleeve cap  100  serves to introduce a flow of inlet air entering through the inlet port  24  and inlet chamber  26  and passing into the plenum  32  by way of the perforation  30 . Thus, the cover  112  or cover portion  112  of the control module  110  may tend to effect or create the chamber  32  or plenum  32 . 
         [0124]    Air passing through the chamber  32  will tend to cool the electronics  114  and other devices on the control module  110 . For example, the electronics  114  may include circuit components, micro switches, wiring, and so forth. Typically, a recess  116  in the module  110  registers with and provides space for the conduit  108  to pass therethrough. 
         [0125]    Various apertures  118  may be provided in various components in order to receive fasteners. Fasteners may thereby secure the various components  12 ,  14 ,  16 ,  18 ,  80 ,  100 ,  110  together. 
         [0126]    In that regard, a control panel  120  may actually be provided with an aperture  122  supporting exit or passage of flows of air out from the exit passage  54 . The aperture  122  may be sufficiently large to actually fit around the conduit  108 , or may simply butt up against the conduit  108 , thereby providing continuation of the exit passage  54  through the control panel  120 . In order to fit, the lobes  126   a ,  126   b  may match the lobes  106   a ,  106   b  respectively in the cap  100 . 
         [0127]    A principal function of the control panel  120  is to provide buttons  124 , such as, for example the buttons  124   a ,  124   b ,  124   c . Herein, trailing letters behind reference numerals indicate specific instances of the item identified by the reference numeral. Accordingly, it is proper here to speak of a reference numeral alone, or a reference numeral with a trailing letter. The trailing letter indicates a specific instance. The reference numeral indicates all instances of the item. Thus, it is not necessary to cite every trailing reference letter, since a single mention of a reference numeral necessarily includes all of the specific instances identified in particular locations by the reference letters. 
         [0128]    The buttons  124  may control various operational characteristics. For example, it has been found that users may be subjected to substantial trial and error in trying to adjust flow rates. For example, in other embodiments of apparatus and methods, controls have been implemented that control duty cycle, total time that the scented air may be injected into the atmosphere out of any overall period of time. For example, previous inventions by the instant inventor controlled the duration of systems in an “on” condition injecting scented air into the surrounding environment. Likewise, the overall time period was controlled. In other embodiments, the time “on” and the time “off” conditions together added to the total time for a single cycle. Thus, the fraction of time in the on condition can be controlled by controlling either the fraction of on time in the total cycle time or the comparative time as related to the delay time or comparative time off. 
         [0129]    Here, in certain embodiments, the buttons  124  may control other parameters that are already integrated or have integrated the proportion of time on, the proportion of time off, the rate of flow, and the amount of introduced content  56  being entrained within the air flow. 
         [0130]    Typically, the rim  128  on the cap  80  or housing cap  80  may provide a certain amount of protection, and rapid registration during installation. The control panel  120  will thus fit neatly, predictably, and stably onto the housing cap  80 . A plate  129  may act as a wall  129  or cover  129 . Meanwhile, seals  130  may be provided. The cavity  132  inside the cap  80  provides space for any of the electronics  114  on the control module  110  to be contained within the envelope of the cap  80 . 
         [0131]    Referring to  FIGS. 4 through 13 and 20 through 29 , the design and appearance of a system  10  in accordance with the invention may be comparatively tall and narrow. This provides many benefits, some functional, and some from a design point of view. Thus, the views embodied in these figures illustrate the design of one embodiment. The ribs  74  may be dispensed with by thickening the wall  86  of the body  70 . Likewise, different materials may be formed of a foamed or expanded polymer rather than any solid molded polymer in forming the housing  14 . 
         [0132]    Referring to  FIGS. 14 and 15 , while continuing to refer generally to  FIGS. 1 through 29 , one may think of a passage  50  such as the annulus  50  between the sleeve  16  and the housing  14  as a conduit  50  carrying a fluid. The fluid is actually in two phases. One phase is vapor or gas such as air. The vapor may also include a certain amount of evaporated liquid content  56  from the reservoir  12 . 
         [0133]    In the illustrated embodiment, the flow  138  along the passage  50  is laminar. Accordingly, the flow  138  is distributed with a laminar velocity profile  140  or profile  140 . The profile  140  reflects the variation in velocity  150  across a distance  146  measured from some origin  148 , such as a wall, a center line, or the like along the passage  50 . 
         [0134]    In laminar flow  138 , the flow  138  may be thought of as being represented by stream lines  142 . The stream lines  142  effectively pass along a certain region of a passage  50 . The velocity  150  measured at any distance  146  in the passage  50  is effectively the same. Thus, a centrally located stream line  142  indicates the maximum velocity in the passage  50 . Meanwhile, velocity typically distributes along an effectively parabolic profile  140  eventually arriving at a zero value of velocity  150  at each wall  144 . 
         [0135]    In a system  10  in accordance with the invention, the overall distance  146  across the entire passage  50  is comparatively small compared to the length of the path in the direction of the velocity  150 . For example, in a system in accordance with the system  10 , the gap  50  or passage  50  is on the order of tens of thousandths of an inch. For example, a gap  50  of from about 50 to about 100 mils (thousandths) of an inch (e.g., a few millimeters) represents the total distance  146 . 
         [0136]    Meanwhile, the overall length along the path of the flow  138  may be a matter of multiple inches, for example, about two inches (five centimeters). An effect of the velocity profile  140  is that comparatively smaller droplets that are sufficiently small to effectively remain with the surrounding air, tend to operate or travel exactly as the vapor (air) in traveling along the passage  50 . 
         [0137]    By contrast, comparatively larger droplets are affected by faster air passing by them closer to the center or origin  148 . Meanwhile, the velocity  150  is zero at the walls  144 . Accordingly, larger droplets, of the second, heavier phase, generally, will be driven toward the outer walls  144 . Thus, the closer to the origin  148  or the shorter the distance  146  from the origin  148 , the faster the velocity  150  of flow  138 . This results in the greater the tendency to carry only comparatively smaller droplets, the larger droplets having drifted out toward the wall  144 . 
         [0138]    At the wall  144 , any impact of a liquid droplet will typically tend to cause coalescence or adherence to the wall  144 . Some fracturing may create smaller particles. Thus, comparatively larger droplets move to the outside boundaries  144  of the passage  50 , thus separating them out from the flow  138 . 
         [0139]    Referring to  FIG. 15 , one may think of the different regions  152  of the flow  138 . In general, the velocity profile  140  illustrates how the velocity  150  actually varies across the channel  50  or passage  50 . However, one may think of each of the sections  152  as a cylindrical core within a circular passage  50 , or as a flat plate, effectively, in the annular passage  50  in accordance with the invention. 
         [0140]    Closer to the center, the section  152   a  is traveling at the highest velocity  150 . similarly, the section  152   b  is traveling at a lower velocity  150 . Meanwhile, reduced velocity  140  in the section  152   c  ultimately leads to a zero velocity  150  at the wall  144 , and its lowest velocity in the section  152   d.    
         [0141]    Thus, the various droplets  160  are subject to drifting  156  or drift  156  toward the walls  144 . The comparatively larger droplets  160  will tend to lag the air flow and drift more laterally, toward the wall  144 . The comparatively smaller droplets  160  will tend to entrain more completely with the surrounding air in the bulk flow  138 . 
         [0142]    It is important to understand that fluid drag exists between the bulk flow of air and the droplets  160 . Meanwhile, momentum is mass multiplied by velocity. The velocity of the drift  156  is affected by the speed of the flow  138 , or the velocity  150  of the bulk flow  138 . However, because the momentum of a comparatively larger particle is greater (greater mass) than the momentum of a comparatively smaller particle, fluid drag must exert more force in order to provide the impulse. Impulse is force over (multiplied by) time which equates to a change in mass times velocity. 
         [0143]    In the illustration, one may think of comparatively smaller droplets  160  as having motion which, if not Brownian, is at least so overwhelmed by the fluid drag on the individual particles  160 , that those particles  160  move freely with the air. In contrast, the additional momentum and especially the relationship between surface area, or even cross-sectional area compared to overall mass and therefore momentum, has a dramatic effect (reduction) on the ability of fluid drag to change the direction of a larger particle  160 . 
         [0144]    Accordingly, comparatively larger particles  160  have a lower ratio of fluid drag force (proportional to cross-sectional area of the droplet  160  in the flow  138 ) compared to the momentum (mass times velocity, where mass is a function of diameter to the third power). Accordingly, as diameter of a droplet  160  goes up, mass goes up as a third power of diameter. Meanwhile, fluid drag only goes up as a square of diameter (cross-sectional area, in other words). 
         [0145]    Referring to  FIG. 16 , in general, the flow  138  may be characterized by various dimensionless numbers, such as that of equation one. Here, N represents the Reynolds number. A Reynolds number represents a dimensionless number that relates the momentum forces to the frictional forces in a moving fluid. Thus, density and velocity as well as a significant length such as a dimension of a passage  50  control the numerator (upper) terms in the Reynolds number, while the viscosity is a denominator (lower) term. Again, this information is all available in standard engineering textbooks and other analyses. 
         [0146]    Thus, density times velocity times a significant length, such as the entire effective diameter (typically distance  146  across the passage  50 ) represents the numerator. Viscosity represents the denominator. Meanwhile, all the units must be appropriate whether using an English system or the SI (international systems) of units. 
         [0147]    Here, a Reynolds number is far below the threshold of about 2,000 (usually 2100). Again, 2,000 has no units, as it is a dimensionless number. In a system  10  in accordance with the invention, the Reynolds number is well into the laminar region, and does not even approach the value required for transition to turbulent flow. 
         [0148]    In one illustrated embodiment, it has been found that a pump in the drive system  18  having a dead head pressure available of about thirteen psi (about one pascal) flows with about one quart per minute (0.9 liters per minute) of flow  138  when restricted only by the natural drag of the system  10 . In one embodiment, a flow of about a pint per minute (0.45 liters per minute) flows at about a pressure of 0.7 pounds per square inch (0.05 pascal). In this instance, the orifice is about 0.015 inches (or about 0.5 millimeters). 
         [0149]    Drag force, designated by F in  FIG. 16 , is equal to a combined group of constants referenced here by the letter K multiplied by the cross-sectional area of the object or droplet  160  on which the drag is acting, multiplied by the square of velocity. Velocity, represented here by the letter V, is the relative velocity between the droplet  160  and the surrounding fluid. Meanwhile, the drag force operating over a period of time is equal to the mass (M), multiplied by the change in velocity, V for a net change in momentum which is shown as the change (delta) in the overall momentum represented by MV. 
         [0150]    Referring to  FIG. 17 , in a system  10  in accordance with the invention the system  10 , itself may be installed, supported, ensconced, hidden, presented, or otherwise placed in, on, within, or in some other relationship with various cases, housings, or the like. For example, in the illustration, various means of positioning or locating the system  10  may be used. Thus, the system  10  is adaptable to virtually any décor, any design concept, or any environment. Whether in a floral arrangement, stand alone sculpture, or hidden within some other object, the system  10  need only receive electrical power to operate the drive system  18 . Since the reservoir  12  and the entire eductor  20  exists within the system  10 , no other constraints need be placed on the system  10  in order to operate. 
         [0151]    In the illustrated examples, an air purifier  164   a  may include a system  10  in accordance with the invention. The system may be in close proximity to an intake port, outlet port, or simply nearby. In some embodiments, the system  10  may actually output its flow into the air stream passing through the air purifier, typically downstream of the purification process. 
         [0152]    Likewise, a portable unit  164   b  may fit a cup holder in a vehicle, or be free-standing on a flat surface. For example, the unit  164   b  may include batteries or other power source to run the drive in the system  10 . 
         [0153]    Other shapes and devices such as a vase  164   d  or goblet  164   d  may be adapted to contain a system  10 . Likewise, a floral arrangement  164   e  may ensconce the self-contained system  10 . A clock radio  164   f  or other alarm clock  164   f  may include two systems  10 , one for a wake-up scent and one for a sleep-time scent. 
         [0154]    Air conditioning units  164   g  may be easily adapted to include a system  10 , in which only a small portion of the overall structure is visible. In fact, in some embodiments, it may be placed inside a vent. However, the illustrated embodiment is most easily accessed and controlled. Meanwhile, conventional dispensers  164   h  of disinfectants and the like, used as wall-mounted units  164   h  in many commercial establishments and public restrooms may also be adapted to receive a system  10  providing aromatic conditioning of the air. 
         [0155]    Referring to  FIGS. 18 and 19  and  FIGS. 1 through 29  generally, some modifications to a system  10  in accordance with the invention in this embodiment may include, for example, locating the wall  98  of the sleeve  16  surrounding the drive  18  (pump and motor) eccentrically with respect to the body  70  of the housing  14 . Accordingly, the gap between the wall  98  and the wall  86  is not uniform about the entire circumference. Also, a relief slot may be cut into the wall  86  to tune the performance as showing the wall  86  thickness on the right. This results in a larger effective diameter (hydraulic diameter) on one side of the passage  50  between the nozzle  42  and the final transit drift  52 . On one side, the gap is smaller. The effective diameter, typically becomes the gap thickness when small gaps form the channel  50  or annulus  50 . Thus, fluid drag is reduced in the passage  50  as the effective diameter (gap) and resulting Reynolds number increase. 
         [0156]    In the illustrated embodiment, the seal  66   b  may be an O-ring, but is illustrated in this embodiment as a grommet providing additional filling and fitting for the interface between the nozzle  38 , particularly near the plenum  36  and the barrel  96  of the sleeve  16  containing a drive  18  (motor and pump). 
         [0157]    The top cap  80  that closes off the housing  14 , still relies on buttons  124 . However, those buttons  124  may pass through apertures  166  in a cover  168 . The cover  168  is itself then covered by a panel  120 . This panel  120  may be, effectively, a membrane  120 . By touching the membrane  120 , a user may actuate any of the switches  124 , including a power button  124   a , as well as the timer control buttons  124   b ,  124   c . For example, the target  124   d  on the membrane  120  may depress the power button  124   a  in response to finger pressure. 
         [0158]    Indicator lights  164  suitably identified may shine through apertures  162  or windows  162  rendering the lights  164  visible through the membrane  120  or cover  120 . In this embodiment, the button  124   a  is effectively a button  124   a  actuating inside the cap  80 , under the touch location  124   d  that represents and contacts that button  124   a  under the membrane cover  120 . 
         [0159]    Relief may be provided in order to permit the conduit  108  to pass therethrough on its way to exiting the system  10 . Also, the stack up of components that form the cap  80  may be secured together by fasteners. The fasteners, such as screws, rivets, bolts, or the like may pass through individual components, such as through the apertures  178  into standoffs  176  for the purpose. Standoffs  176  provide for alignment of components by means of recesses  116  or relief  116  spaced apart and fitted to the various standoffs  176 . Meanwhile, fasteners extending down through apertures  178  may be received into central hollows or apertures in the standoffs  176 . Thus, the cap  80 , once assembled with components fastened together may be handled as a single piece  80  or assembly  80 . 
         [0160]    In the illustrated embodiment, an apparatus  10  in accordance with the invention may be provided with a foam layer  172  effective to dampen sound and vibration originating from the drive  18 . The foam layer  172  may be positioned between the drive  18  and the wall  98  of the sleeve  16 . 
         [0161]    In some embodiments, electrical plugs  170  may be provided to electronically connect the drive  18  to an outside source of power in a convenient manner. One or more plugs  170  may be provided in order to provide charging, power, control, or the like. In any basic embodiment, a single plug  170  may include multiple connections in order to carry one or more circuits of electricity as appropriate. In the illustrated embodiment, a controller  110  may be built upon a printed circuit board  110  on which electronic components  114  are interconnected to control timing, logic, switching as described above, and so forth as necessary. 
         [0162]    The system  10  has been found to be somewhat more robust, particularly in view of the energy and dynamic nature of the drive  18 , by provision of ribs  174  to add structural strength to the walls  98  of the sleeve  16  surrounding and supporting the drive  18 , and supporting the eductor chamber  40 . For example, the eductor  20  houses and supports the drive  18  by means of the grommet  66   b  or other seal  66   b . Similarly, the grommet  66   b  or seal  66   b  forces the nozzle  38  down into the eductor chamber  40 . Substantial force may be applied to the grommet  66   b , in view of the effect of the cap  80  seating against resilient seals  66   c  applying force through the drive  18  to the well  94  and wall  98 . The ribs  174  have been found effective to stiffen and strengthen the structure of the walls  98  of the sleeve  16  containing the drive  18 , and strengthens the well  94  and securement thereto. 
         [0163]    The annulus  50  may be tuned or trimmed. In this embodiment, the gap  50  may be about 0.050 to about 0.10 in inches across. Output is greatly reduced below about 0.030 inches. Separation degrades as the gap  50  increases over about 0.10 inches. The thickness of 0.060 inches in the wall  86  of the barrel  70  may be relieved by marking a channel therein of about 0.030 in depth and about 0.20 to about 0.35 width. A quarter inch of width tapering from a depth of zero at the bottom to about 0.030 inches at the top of the wall  86  (a height of about two to tow and a half inches) has been found effective to improve output with no loss in separation quality for oils deemed comparatively more viscous and more resinous, such as sandalwood and patchouli. Alternatively the entire gap  50  may be increased. 
         [0164]    The present invention may be embodied in other specific forms without departing from its purposes, functions, structures, or operational characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.