The present apparatus and method relate generally to the area of fluids purification and in particular to the area of fluid purification by application of an intense electric field to the fluid flow to destruct, eliminate or inactivate germs, viruses and other microorganisms. The electric field is applied by specially shaped obstacles which in addition to the electric field application form a turbulent fluid flow for better efficacy of eliminating the microorganisms.
Fluid purification is a process of removing undesirable chemicals, particles, and microorganisms such as parasites, bacteria, algae, viruses, fungi, and others. Where the particles may be removed by filtration, the destruction or elimination of microorganisms is usually performed by chemical methods, for example by disinfectants like chlorine or by exposure to ultraviolet light.
In chemical fluid purification methods an antimicrobial agent is placed directly into a fluid to be purified. The agent may inhibit growth of microorganisms or eliminate and destroy the microorganisms. The residuals of the antimicrobial agent may impart on the purified fluid undesired taste, smell, or color limiting the further purified fluid use.
It is known that bacteria, viruses and other microorganisms may be inactivated or eliminated by strong electric field. The efficacy of destroying these microorganisms depends on the electric field intensity and the duration of the field application to the fluid. Some of the existing art teaches applications of electrostatic field as filters for arresting dust particles. The principles employed in these filter applications are based on use of the Coulomb force acting by the electric field on the charged particles to divert them from the streamline and then attract them. Typically, electrostatic field is applied to a flow of fluid flowing between two opposing electrodes, mostly parallel plates. Practically, such architecture forms a flat capacitor configuration that produces a uniform electric field in the fluid passageway. Voltage breakdown constitutes a major limiting factor on the intensity of the electric field generated in this configuration.
Since the intensity of the electric field is limited, such electric field application methods are not effective in eliminating microorganisms that may be present in a fluid. In order to effectively inactivate the microorganisms in a fluid, it would be desirable to have fluid purification apparatuses that include elements amplifying electric field and focusing its effect in specific gate zones where the fluid flows. The elements should be of such form and shape that they can be located in the fluid flow gateways and passageways and therefore act to inactivate or eliminate microorganisms present in the flow.
It would also be desirable to increase the duration of the electric field and fluid interaction. This will increase the interaction time between the amplified electric field and the fluid flow enhancing the electric field purification action. Fluid flow vortex, for example in a turbulent flow, would also be beneficial for fluid purification, since it will involve interaction of larger amount of fluid volumes with the electric field. Currently, there are no apparatuses or devices known to the authors of the present disclosure that support the described above functionality.
There is therefore a need for an apparatus operative to accept a fluid flow, apply to it an enhanced electric field sufficient to inactivate different microorganisms, form a flow ensuring intensive fluid mixing and extend the time of electric field fluid interaction. An apparatus that is simple in operation and maintenance and capable of providing a fluid flow free of different microorganisms.
The term “fluid” as used in the present disclosure means gases such as air and other gases and liquids.
The term “microorganisms” as used in the present disclosure incorporates bacteria, viruses, and other microorganisms.
The term “sheet” or “ a sheet of material” as used in the present disclosure means a generally flat, multilayer article with a layer of an electrically conducting material embedded between at least two layers of electrically insulating material. One or both surfaces of the sheet may be patterned by a pattern of protruding elements, or ribs. The sheet may be of round (disc) shape having a hole in the center of the sheet, rectangular, or any other arbitrary shape.
In the context of the present disclosure the terms “radial ribs” used in describing disk shaped sheets are equivalent to the term “longitudinal ribs” for other than having circular symmetry sheet shapes.
In the context of the present disclosure the terms “tangential ribs” used in describing disk shaped sheets are equivalent to the term “transversal ribs” for other than having circular symmetry sheet shapes.
As used in the context of the present disclosure the term “purification” and “fluid purification” primarily means destruction, elimination or inactivation of microorganisms such as parasites, bacteria, algae, viruses, fungi, and others.
In the context of the present disclosure the terms “gateways”, “gate zones”, “gate points”, and “passageways” are used to describe different elements forming and directing fluid flow channel. “Passageway ” means a corridor like space formed to connect between the inlet port to the outlet of the fluid flow. “Gateway” means a narrower place that resides in the Passageway, e. g., orifice, which restricts the flow in the Passageway. “Gate zones” means the space in proximity to the Gateway and “Gate point” means the narrowest cross section point of a Gateway.
A fluid purification apparatus includes an assembly of sheets that have on one or both surfaces of the sheet a pattern which may be a pattern of protrusions or ribs. When two sheets are assembled such that that the patterned surfaces face each other, some of the ribs are operative to form a fluid passageway between the sheets and some of the ribs form gateways that are operative to generate a turbulent fluid flow across the passageway. The sheet includes embedded electrodes extending through the area of the sheet.
Some of the ribs are a type of flow obstacles located along the passageway that operate to divert the flow in a number of directions and to create turbulent flow for extending the time of residence therefore increasing the duration of the electric field interaction with the fluid achieving even more uniform purification for any fluid volume element flowing in the gateway and passageway between the sheets.
Some of the ribs include special electric field shaping features or field shapers implemented as an integral part of the ribs. These field shaping features generate in designated locations of the fluid passageway termed gate points and gate zones a strong localized electric field by amplifying the electric field applied to the passageway through the electrode to a level sufficient to destroy different microorganisms. The gateways formed by the ribs of the opposing sheets extend the length of the fluid flow path and accordingly the time the fluid resides in the passageway. Extended fluid in the passageway residence combined with strong electric field at the gate zones supports better fluid purification action.
Exemplary embodiments of the present apparatus and method will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments of the apparatus and of the method are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the apparatus and method may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “upward,” “downward,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting.
Longitudinal ribs 124 protrude out of surface 104 on a dimension exceeding that of transversal ribs 128 and 228 and another sheet 100 placed over the first sheet 100 rests with its surface 204 on longitudinal ribs 124. Accordingly, the passageway may be formed between two adjacent longitudinal ribs 124, surface 104 of the first sheet 100 and surface 204 of the second sheet 100. In the stack the transversal ribs 228 would typically be located about the center line 138 (
When high voltage is supplied to the electrodes 616, it induces an electric charge at transversal ribs 128 and 228 located in the passageway 504 and in particular on the wedge shaped terminations 132 and 232 to cause electric charge concentration about the terminations and amplify the applied electric field forming an intense electric field about the wedge shaped terminations 132 and 232 of the transversal ribs. The magnitude of the intense electric field formed at the terminations 132 and 232 exceeds three to four times the electric field formed without shaped ribs.
In an additional exemplary embodiment the most inner, with respect to fluid entrance side 508 transversal ribs 524 and 528 may have an edge step termination. These edge step terminations 524 and 528 are made to align the engagement of both sheets when stacked or assembled together.
An explanation of the physical rules governing the process of amplified electric field formation in-between the sheets, and in particular at the gate points or zones, is provided below and illustrated in
Numerals 700 and 704 indicate opposing sheet 708 surfaces. Each of the sheets 708 has a thickness (t) and the obstacle 728 protrudes by a dimension (h) over the surface 700. Sheets 708 may be made of a plastic or dielectric material. An air gap of magnitude (s) forms a gate zone or point 716. Metallic foils or electrodes 720 and 724 are connected to high voltage source 712 generating a voltage V. The distance (d) between the foils is a sum of the thicknesses of the insulating or dielectric material of sheets 708, the width (s) of the gap, and the height of the obstacle (h). Accordingly, d=2t+h+s. In this configuration the electric field between the electrodes is the same as between flat capacitor plates. For example, in case of plates without dielectric layers, the field intensity (E) is defined as: E=V/d. For a combined media of different dielectric materials the displacement D in each layer is related to the electric field intensity by: D=εE and to the applied voltage V by: V=D(2t+h)/εp+Ds/ε0, where εp and e0 are dielectric constants for plastic and air respectively. εp is often expressed as er.ε0 where εr is a relative proportionality coefficient. The term (2t+h) can be replaced by (d-s), then the above equation may be converted to:
V=D[d+s(εr−1)]/εr. ε0. The electric field Eg in the air gap (s) is related to the displacement D by Eg=D/ε0, thus: Eg=V.εr/[d+s(εr−1)].
(The notations used are similar to those used in “Classical electrodynamics” By J. Jackson, second edition pages, 145-145 where the electrical displacement D is defined and the Coulomb law expression given in page 217 and V=∫{Edx} along the path from one electrode to the other, which is the basis for the voltage equation below, and also for V=E.d in a uniform length d. The relation D=εE is local. The boundary conditions of D at the interfaces are given by equation 4.40 on page 146 of Jackson, and since there are no free charges at the interface fluid-dielectric, the displacement D is the same in both materials i.e. continues in the interfaces.) A similar approach may be found for example, in:
http://www2.warwick.ac.uk/fac/sci/physics/teach/module_home/px263/handouts20 08/boundarye.pdf)
The relative dielectric coefficients er for most plastic materials are between 2.5 to 4.0. This coefficient may even be significantly increased by a proper supplemental filler, e.g. ceramic powder, into the plastic material. From the last equation one can find out that the dielectric material acts as multiplier of the electric field intensity at the gate zone, by a factor of about 3. The same equation also teaches that the field is inversely proportional to the gap (s).
Based on this model, it is possible to estimate the field intensity for a practical example of application of this apparatus and method.
The thickness of the plastic or dielectric layer is: t=0.5 mm
The distance between the conducting foils is: d=1.520 mm
The gap width is: s=0.020 mm
The applied voltage can be set to 6,000 Volts. This value is safe to avoid any voltage breakdown and arching.
The relative coefficients for plastic is taken in this example as: εr=3.0
The resulting field intensity at the gate point will be: Eg=11,538 Volts/mm
In order to demonstrate the contribution of the electric field shapers amplifying the electric field, we can compare this result with a reference case where h=0. In this case s=d-2t, the equation for the field becomes: E=V.εr/[d. εr−2t(εr−1)] and using the same as above parameters the reference field intensity without the field shapers is: E=7,031 Volts/mm Evidently the electric field amplification factor achieved by the protruding electric field shapers is 1.64.
Moreover, the above results can be compared to a reference value of the two plates without the dielectric or plastic layers. In this case the field is E=V/d=6,000/1.52=3,947 Volts/mm, or about ⅓ of the field intensity amplified by the field shapers. In consideration of this example one should count the fact that the dielectric strength of air can sustain up to about 3,000 Volts/mm, thus the dielectric or plastic coating of the plates is necessary to prevent voltage breakdown and arcing in the gate zones.
In view of the description of the above embodiments and the special features attained by the unique design of the purification sheets with patterned surfaces disclosed herein and, in particular the amplification of the electric field in the gate zones by the shaped terminations of the transversal ribs, the field intensity that can be generated by such sheet is 3 to 4 times more intense. From different publications (For example, Dan Bu et al, Journal of Electrostatics, Vol. 63, Issues 6-10, June 2005, 10th International Conference on Electrostatics) it is known that microorganisms such as bacteria, viruses and other microorganisms were inactivated or destroyed by electric field with field intensities between 1,500 Volts/mm to 3,000 Volts/mm According to the calculation presented above, the purification apparatus constructed to with described above sheets may generate a field intensity of over 11,000 Volts/mm, far exceeding the threshold required for microorganisms destruction.
Radial ribs 824 protrude out of surface 804 on a height exceeding that of tangential ribs 828 and 1028 and another sheet 800 placed over the first or lower sheet 800 will lay on ribs 824. Accordingly, the passageway may be formed between two adjacent radial ribs 824, surface 804 of one of the discs 800 and surface 1004 of the other disc or sheet 800. In the stack the segmented transversal ribs 1028 would typically be located about the center line 838 (
The side edges of the tangential ribs 1228 or transversal obstacles forming the gate zones may be made either with flat ends to induce amplification of the electric field in the gate points, or with sharp ends to shape the field lines and thereby induce further amplification of the field in the gate points. This embodiment ensures a longer fluid path and increases the time the fluid resides in-between the inlet and outlet of the passageways. Since in this embodiment only one of the sheet or disc surfaces is patterned it is easier and less expensive to manufacture these types of discs.
This clearance forms gate zones and gate points 1436 located between the edge 1432 of the tangential rib 1428 and the alternating sides of radial ribs 1424. Arrows 1450 indicate fluid flow. The fluid flow is being deflected alternately to the left and to the right of the gate zones, along the curved labyrinth of the passageway, thereby the length of flow path is increased so that the fluid resides longer time in the passageway as well. The sharp edges 1432 of the tangential ribs 1428 amplify the electric field in the gate points of gate zones 1436 enhancing the fluid purification action.
Each of the described above sheet configurations may be used to form multiple sheet stacks employed in fluid purification and disinfection apparatuses. The process of fluid purification will be described now.
Initially, a stack of sheets such as sheets 100 or 800 (or 1200, 1400) of electrically insulated material with a pattern of longitudinal and transversal ribs and an electric contact embedded in each of the sheets is formed. The stack contains one or more fluid passageways formed by the space between the longitudinal ribs 124 (824, 1224, 1424) spanning along one surface of the disc. An assembly of the stack of sheets is mounted into an existing or new fluid purification system that includes a means of blowing or pumping a fluid, thereby introduces or couples the fluid flow to be purified to the passageways and gateways and a flow of the fluid through the passageway from one end of the passageway to the other is established.
The fluid flow carries the fluid along the passageway through gate zones formed by the transversal or tangential ribs distributed along the passageway. In some embodiments, the transversal or tangential ribs protrude from the sheet surface on a dimension smaller than the longitudinal ribs protrude and form a narrow gap or clearance between the transversal rib and the surface of the adjacent sheet. The transversal ribs operate as fluid flow obstacles. The gap or clearance between the transversal rib and the surface of the adjacent sheet is termed gate zone or gate point. The fluid flow is forced to pass through the gate zone. The gap is operative to deflect the fluid flow between the sheet surfaces and induce localized turbulence in the fluid flow.
A similar effect is produced when the transversal or tangential ribs are slightly shorter than the width of the passageway. The gate zone is formed at the clearance between the ends of the transversal ribs and the longitudinal ribs.
The electrical field generated by the high voltage supplied to the electrodes may be sufficient to destroy different microorganisms. The wedge shaped ends of the transversal ribs focus and amplify the electrical field in predetermined locations of the passageway, which are the gate zones. The field amplification is such that the electric field intensity in the gate zones may exceed the electric field formed by not shaped ribs three to four times. The electric field amplification or enhancement is achieved by the use of the dielectric material, novel surface pattern and/or by the sharp edges of the fluid flow obstacles. The amplified electric field intensity is sufficient to destroy or eliminate germs, viruses and other microorganisms and therefore the effectiveness of the apparatus and method to inactivate or eliminate germs, viruses and other microorganisms is substantially enhanced.
The described stacks of sheets may be used in manufacture of fluid purification and disinfection apparatuses. They are operative to purify a large range of fluid flows flowing with different speeds. The purification action includes different microorganisms inactivation and destruction.
While the invention has been described with respect to several preferred embodiments, it will be appreciated that these are set forth merely for purposes of example, and that many other variations, modifications and applications of the invention may be made.
This application is being filed under 35 U.S.C 371 as a United States national patent application based on International Application Number PCT/IL2009/000950 filed on Oct. 1, 2009, which application claims priority to the United States Provisional Application for Patent that was filed on Oct. 28, 2008 and assigned Ser. No. 61/197,408, which application is hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IL09/00950 | 10/1/2009 | WO | 00 | 4/13/2011 |
Number | Date | Country | |
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61197408 | Oct 2008 | US |