US20090273103A1

US20090273103A1 - Nanofluid Production Apparatus and Method

Info

Publication number: US20090273103A1
Application number: US11/992,350
Authority: US
Inventors: Sadatoshi Watanabe
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-09-23
Filing date: 2006-09-22
Publication date: 2009-11-05
Also published as: JP4222572B2; US20100010422A1; JP2008246486A; JPWO2007034913A1; WO2007034912A1; JPWO2007034580A1; WO2007034913A1; JPWO2007034912A1; WO2007034580A1; US20090293920A1; US8726918B2

Abstract

The present invention provides a nanofluid generating apparatus and method of use thereof that is capable of efficiently generating nanofluid by having relatively simple and inexpensive construction, being capable of continuously and stably generating nanofluid, being easy to handle, dramatically reducing manufacturing costs, and being able to generate and select nanofluids according to various usages. An apparatus for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprising: a gas-liquid mixing chamber 7 for forcibly mixing supplied gas and liquid by generating turbulence therein; a pressurization means 4 for applying pressure to the gas and liquid to be supplied to the gas-liquid mixing chamber 7; a nano-outlet 20 for discharging pressurized gas-liquid mixture fluid to outside of the gas-liquid mixing chamber 7 to thereby generate nanofluid; and a filter mechanism F for removing nanofluid containing gas bubbles with diameter equal to or greater than a predetermined value from the generated nanofluid.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. 119 based upon U.S. Provisional Application No. 60/719,937, filed on Sep. 23, 2005 and the International Patent Application No. PCT/JP2006/301736, filed on Feb. 2, 2006. The entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an apparatus and a method for generating nanofluid containing nanobubbles, which are gas bubbles with diameter less than 1 μm; an apparatus and a method for generating beverages containing nanofluid; an apparatus and a method for treating dermatosis using nanofluid; and an apparatus and a method for assisting the growth of organisms using nanofluid.

BACKGROUND OF THE INVENTION

In general, submicroscopic gas bubbles with diameter less than 1 μm (1000 nm) are called “nanobubbles,” whereas microscopic gas bubbles with diameter equal to or greater than 1 μm are called “microbubbles.” The nanobubbles and microbubbles are distinguished from each other. These nanobubbles and microbubbles have been known for various functionalities, efficacies and manufacturing methods shown, for example, in the following patent documents.
Patent Document 1 describes microscopic gas bubbles (microbubbles) characterized for having diameter less than about 30 μm upon their generation at normal pressures; gradually miniaturizing over a predetermined lifespan; and vanishing or dissolving thereafter.
The Patent Document 1 also describes examples and their results of applying the microbubble characteristics such as gas-liquid solubility, cleaning function or bioactivity enhancement to improve water quality in closed bodies of water such as a dam reservoir, enhance the growth of farmed fish and shellfish or hydroponic vegetables and the like, and sterilization or cleaning of organisms.
Patent Document 2 describes a method for generating nanobubbles with diameter less than 1 μm by decomposing part of liquid therewithin. Also Patent Document 3 describes a method and an apparatus for cleaning objects using nanobubble-containing water.
Patent Document 4 describes a method for producing nanobubbles by applying physical stimulation to microbubbles in liquid to thereby rapidly reduce the bubble size. Furthermore, Patent Document 5 describes a technology according to oxygen nanobubble water consisting of an aqueous solution comprising oxygen-containing gas bubbles (oxygen nanobubbles) with 50-500 nm diameter, and a method to produce the oxygen nanobubble water.
Moreover, Patent Document 6 discloses an apparatus for generating microbubbles by swirling pressurized liquid and gas in a cylinder to generate pressurized gas-liquid, and discharging the pressurized gas-liquid from a nozzle with a shape irregularly flared towards downstream to thereby generate the cavitation phenomena. Still further, Patent Document 7 discloses a technology for generating ionic water by creating microbubbles with diameter 50 μm or less.
As described above, nanobubbles have not only the microbubble functionalities, but also excellent engineering functionalities to directly affect organisms in their cellular level, allowing a broader range of applications, such as semiconductor wafer cleaning and dermatosis treatment, than that of microbubbles and nanobubbles are expected to have even higher functionalities in the future.
Patent Document 1: JP-A-2002-143885
Patent Document 2: JP-A-2003-334548
Patent Document 3: JP-A-2004-121962
Patent Document 4: JP-A-2005-245817
Patent Document 5: JP-A-2005-246294
Patent Document 6: JP-A-2003-126665
Patent Document 7: JP-A-2006-43642
It has been verified that the nanobubbles described above are generated instantaneously when microbubbles collapse in the water, and are known for their extremely unstable physical characteristics. Therefore it is difficult to put nanobubbles to practical use by stably producing and retaining them for an extended period of time.
For this reason, the Patent Document 3 is suggesting to generate nanobubbles by applying ultrasonic waves to decomposed and gasified solution. However, ultrasonic generators are expensive, large-sized and difficult to use and perform matching, prohibiting their wide use.
Also the Patent Document 1 discloses a method and an apparatus for generating microbubbles by force feeding liquid into a cylindrical space in its circumferential direction to create a negative pressure region, and having the negative pressure region absorb external gas. However, this apparatus only generates microbubbles, and does not stably produce nanobubbles with smaller diameter. Similarly, applying the technology disclosed in the Patent Document 6 does not achieve stable and low-cost generation of nanofluid containing nanoscale bubbles.
Furthermore, the diameter of the nanobubbles in nanofluids that are required for use in various fields is different. For example, in the cleaning of precision equipment such as semiconductor wafers, or the treatment of dermatosis, the size of or space between the members on a board or cells is tens of nm to 100 nm, so nanofluid that contains nanobubbles that corresponds with that becomes necessary. On the other hand, in the improvement of water quality in a closed body of water, the farming of fish and shellfish, or the promotion of growth of hydroponic vegetables, there are no strict diameter requirements, so for example, nanofluid even on the scale of several hundred nm is sufficient for practical application.
In order to solve the problems described above, the object of the present invention is to provide a nanofluid generating apparatus and method of use thereof that has relatively simple and inexpensive construction, is capable of continuously and stably generating a large amount of nanofluid, is easy to handle, and is capable of dramatically reducing manufacturing costs.
Moreover, another object of the present invention is to efficiently generate nanofluid by enabling the generation and selection of nanofluids according to various uses.
In order to achieve the above objective, according to the first aspect of the present invention, there is provided an apparatus for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, having:
a gas-liquid mixing chamber for forcibly mixing supplied gas and liquid by generating turbulence therein;
a pressurization means for applying pressure to the gas and liquid to be supplied to the gas-liquid mixing chamber;
a nano-outlet for discharging pressurized gas-liquid mixture fluid to outside of the gas-liquid mixing chamber to thereby generate nanofluid; and
a filter mechanism for removing nanofluid containing gas bubbles with diameter equal to or greater than a predetermined value from the generated nanofluid.
According to such a structure, nanofluid may be generated which contains gas-liquid mixture fluid with its large fraction of gas and liquid miniaturized to a nano-level by supplying gas and liquid into a gas-liquid mixing chamber provided with a turbulence generating mechanism such as many internal irregular features, forcibly mixing the gas and liquid while applying pressure thereto with a pressurization means such as a pump to generate gas-liquid mixture fluid with its gas and liquid uniformly mixed, and discharging the gas-liquid mixture fluid under pressure from a nano-outlet with a nanoscale channel.
Even among nanobubbles, there are, for example, large differences in function and use according to whether the nanobubbles are ultra-small nanobubbles having a diameter less than 100 n, or nanobubbles having a diameter greater than that. Particularly, in the field of cleaning precision equipment such as semiconductor wafers, or in the field of treatment to improve bioactivity through direct application to biological cells, a nanofluid that is on the same scale as the integration density of elements, or the size of or spacing between cells (50 to 80 n) is necessary. Therefore, in the present invention, a filtration mechanism is provided in order to selectively be able to separate out and use only nanofluids that have a desired diameter or less (or greater) than a diameter that corresponds to a specified use.
In addition, the relatively large-diameter nanofluids that are removed by this filtration mechanism are not suitable for cleaning of precision equipment or for treatment, however, compared to microbubbles, these nanofluid can be expected to have plenty of effectiveness in fields such as the improvement of water quality of closed bodies of water such as dam reservoirs, the promotion of growth of farmed fish and shellfish or hydroponic vegetables, facial and beauty treatments, beverages, and the like. Therefore, in the preferred embodiments of the present invention, a plurality of channels have been provided in order that the nanofluids that are removed by the filtration mechanism can be used in a plurality of different uses.
For example, at the most upstream filtration mechanism (near the outlet), nanotization does not proceed completely and fluid (microfluid) containing micro level bubbles is separated out and removed, after which it is supplied via a circulation channel to a gas-liquid mixing chamber to be used as is as a microfluid. In the next filtration mechanism, nanofluid having a relatively large diameter is separated out and removed and used for growth promotion of fish, shellfish and plants, or for bathing and beauty care. Also, nanofluid having a microscopic diameter that passes through these filtration mechanisms is used for treatment or for cleaning of precision equipment.
On the other hand, when this nanofluid generating apparatus is used exclusively for treatment, it is preferred that nanofluid having a desired microscopic diameter be generated by supplying the nanofluid having a relatively large diameter that is removed by the filtration mechanism again to a gas-liquid mixing chamber via a circulation channel and repeating nanotization.
Here, it is necessary to provide a function for filtering out nanobubbles having a specified diameter on a nano order as the filtration mechanism. For example, it is possible to employ a one-dimensional film with nano sized through holes, which is a ceramic mesoporous thin film that is made using a metal template method or eutectic decomposition method. Particularly, in the metal template method, the size of a one-dimensional structure can be easily controlled, so by using simultaneous etching it is possible to make nano filters having various filtering sizes. By using this kind of a plurality of filters having different filtering sizes, it is possible to easily select and separate out the generated nanofluids according to usage, so that the generated nanofluids can be used without being wasted. Therefore, it is possible to improve the overall generation efficiency.
According to the second aspect of the present invention, there is provided an apparatus for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprising:
a gas-liquid mixing chamber for forcibly mixing supplied gas and liquid by generating turbulence therein;
a pressurization means for applying pressure to the gas and liquid to be supplied to the gas-liquid mixing chamber;
a nano-outlet for discharging pressurized gas-liquid mixture fluid to outside of the gas-liquid mixing chamber to thereby generate nanofluid; and
a circulation channel for introducing part or all of the generated nanofluid into the gas-liquid mixing chamber for circulation.
With this kind of construction, by circulating a micro-level fluid, for example, that has not been sufficiently nanotized, or a nanofluid having a desired diameter or greater when applying a micro-sized nanofluid to a specified field, and supplying the fluid again to a gas-liquid mixing chamber, it is possible to obtain a desired nanofluid. Moreover, by combining the filtration mechanisms of the first embodiment described above, the filtration mechanism can be used to selectively separate out a nanofluid having a desired diameter, and to circulate all other nanofluids. By doing so, it is possible to efficiently generate a nanofluid having a desired diameter.
According to the third aspect of the present invention, there is provided a method for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprising the steps of:
supplying gas and liquid to a gas-liquid mixing chamber; with a pressurization means, pressurizing the gas and liquid before or after the step of supplying gas and liquid;
with a turbulence generating mechanism provided in the gas-liquid mixing chamber, forcibly mixing the supplied and pressurized gas and liquid in the gas-liquid mixing chamber by generating turbulence; and
discharging pressurized gas-liquid mixture fluid from a nano-outlet provided in an exit side of the gas-liquid mixing chamber, to outside of the gas-liquid mixing chamber to thereby generate nanofluid.
With this kind of construction, by supplying a gas and liquid to a gas-liquid mixing chamber that internally comprises a turbulence generating mechanism having a plurality of uneven areas, and forcibly mixing the gas and liquid under pressure by a pressurization means such as a pump, the gas and liquid are evenly mixed and a gas-liquid mixture fluid is generated; then by passing this gas-liquid mixture fluid through a channel that becomes more narrow until it is on a nano order, and outputting the fluid from a nano output while maintaining the pressurized state, it is possible to generate a nanofluid of which much of the gas and liquid of the gas-liquid mixture fluid is reduced in size to a nano level.
According to the fourth aspect of the present invention, there is provided a method for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprising the steps of:
pressurizing liquid with a pressurization means and supplying the pressurized liquid to a gas-liquid mixing chamber;
drawing gas in with a pressure difference between the upstream and downstream of the pressurization means upon actuation thereof and introducing the gas into the liquid;
introducing pressurized gas-liquid mixture fluid into the gas-liquid mixing chamber, and generating turbulence in the gas-liquid mixture fluid by guiding the gas-liquid mixture fluid into repeated bouncing into random directions with a turbulence generating means provided in the gas-liquid mixing chamber; and
releasing the gas-liquid mixture fluid from a nano-outlet provided in an exit side of the gas-liquid mixing chamber, to thereby generate the nanofluid containing the nanobubbles.
With this kind of construction, similar to the method in the third major aspect, it is possible to generate a nanofluid of which much of the gas and liquid of the gas-liquid mixture fluid is reduced in size to a nano level.
With the present invention, it is possible to obtain a nanofluid generating apparatus and method of use thereof that has relatively simple and inexpensive construction, is capable of continuously and stably generating a large amount of nanofluid, is easy to handle, and makes it possible to dramatically reduce manufacturing costs.
Moreover, with the present invention it is possible to obtain a nanofluid generating apparatus and method of use thereof that efficiently generates nanofluids by being capable of generating and selecting nanofluids according to various uses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram and a partial enlarged view of an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the construction of the filtration mechanism of an embodiment of the present invention.

FIG. 3 is an overall perspective view of the generator of an embodiment of the present invention, and a partial enlarged view of the junction section thereof.

FIG. 4 is a drawing showing the construction of the cleaning apparatus of an embodiment of the present invention that is connected to the nanofluid generating apparatus by way of piping.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiments of the present invention are explained below with reference to the accompanying drawings.
FIG. 1A is a cross-sectional schematic drawing of the nanofluid generating apparatus 1 of a first embodiment of the present invention; FIG. 1B is an enlarged view of portion M in FIG. 1A that is indicated by the circle; and FIG. 2 is a cross-sectional schematic drawing of the filtration mechanism F.
The nanofluid generating apparatus 1 comprises: a generator 2, a holding tank 3, a pressurization pump (pressurization means) 4, piping H that runs from the water supply source S to the generator 2 via the pressurization pump 4 and holding tank 3, a filtration mechanism F for selecting or removing nanofluids having a desired diameter, a circulation channel CR that supplies nanofluid that was removed by a primary filter to the holding tank 3 via the water supply source S, and external supply channels 41 a, 41 b for supplying a plurality of kinds of nanofluids that were separated out by a primary and a secondary filter to a plurality of external processing apparatuses 40 a, 40 b.
A water purifying apparatus that is not shown in the figures (for example, Milli-Q Synthesis manufactured by Millipore) is provided in the piping H between the water supply source S and the pressurization pump 4, and is capable of changing water that is supplied from the water supply source S to purified water and supplying that purified water to the pressurization pump 4. The pressurization pump 4 is capable of drawing in purified water from the water purifying apparatus, pressurizing that purified water to 13 to 15 atm, and feeding the purified water to the holding tank 3.
A bypass circuit R is provided such that it branches from the piping H of the upstream side and downstream side of the pressurization pump 4. There is an air intake valve (air inlet means) 21 provided in the bypass circuit R, and this air intake valve 21 is opened as the pressurization pump 4 operates, and is a check valve that draws in outside air.
To explain, as the pressurization pump 4 operates, a pressure difference occurs between the upstream side and downstream side of the pressurization pump 4 in the piping H, and air (outside air) that is drawn in from the air intake valve 21 mixes with the pure water that is pressurized and fed by the pressurization pump 4, and is supplied to the holding tank 3 in this state.
When the pressurization capability of the pressurization pump 4 is 13 to 15 atm, the amount of air intake from the air intake valve 12 is set to about 1 to 3 liters per minute.
Pure water and air that are mixed at a specified ratio is held in a pressurized state in the holding tank 3, however, the setting for the amount held can be suitably changed according to the type of nanofluid being generated or the generating capability of the generator 2.
For example, when generating fluid consisting of the purified water and the air, the pressurization capacity of the pressurization pump 4 is set to 13-15 atm, and the nanofluid generation capacity is set to 40-60 liters per minute, the holding tank 3 capacity of 12-15 liters is large enough.
Also, when modifying water stored in a bathtub or a pool into nanofluid, 1-2 tons of water may be processed per minute by replacing the water supply source S with the bathtub or the pool, and storing in the holding tank 3 and also circulating the nanofluid-containing water generated by the present apparatus.
The generator 2 is formed from a material that has excellent pressure resistance and water resistance such as stainless steel, and is cylindrical shaped with the center axis oriented in the vertical direction. The top end and bottom end are both closed, with an inlet 5 being provided on the top end and an outlet 6 being provided on the bottom end. As will be explained later with reference to FIG. 3, this generator 2 is constructed such that it can be disassembled into a left and right piece, and is such that the inside can be sterilized, disinfected or cleaned (hereafter, collectively referred to as being cleaned).
Provided inside the generator 2 are a first bulkhead plate a1, a second bulkhead plate a2, and a third bulkhead plate a3 for axially separating compartments with predetermined intervals. The internal space from the top surface, on which the inlet 5 is provided, to the first bulkhead plate a1 is called a partition space A, and the internal space from the first bulkhead plate a1 to the second bulkhead plate a2 is called a gas-liquid mixing chamber 7.
The internal space from the second bulkhead plate a2 to the third bulkhead plate a3 is called a valve chest B, and the internal space from the third bulkhead plate a3 to the bottom surface, on which the outlet 6 is provided is called a discharge space section C. The above internal spaces A, 7, B and C are configured as follows.
An inlet body 3 a comprising a supply valve 22 is projectingly provided at the bottom of the holding tank 3, and the supply valve 22 and part of the inlet body 3 a are inserted into the inlet 5, which is provided at the top of the generator 2, using an airtight structure. An open end of the inlet body 3 a protrudes into the partition space A inside the generator 2.
Provided through the first bulkhead plate a1 are two sets of communication bores (through-holes), first communication bores 8 a and second communication bores 8 b, wherein upper ends of each set of the communication bores are positioned concentrically on a circumference of a circle with a unique diameter about the central axis, wherein bores are spaced apart with predetermined intervals. The first communication bores 8 a are located near the central axis of the generator 2 and vertically (axially) provided. The second communication bores 8 b are located near the circumference of the generator 2 and obliquely provided with their lower ends having a larger diameter than a diameter of the upper ends.
Accordingly, fluid passing through the first communication bores 8 a near the central axis flows down vertically, and fluid passing through the second communication bores 8 b near the circumference flows down outward. The partition space A is in communication with the gas-liquid mixing chamber 7 through the first communication bores 8 a and the second communication bores 8 b.
Inside the gas-liquid mixing chamber 7, a conical member 11, which is an integral part of the generator 2, is vertically provided from the center of the lower surface of the first bulkhead plate a1, wherein the central axes of the conical member 11 and the generator 2 align with each other. A rod section 11 a, the upper part of this conical member 11, is in a simple rod shape attached to the lower surface of the first bulkhead plate a1, and a conical section 11 b, the lower part of the conical member 11, is flared into a segmented conical shape.
Part of the conical member 11, especially around the surface of the conical section 11 b, is located directly underneath the first communication bores 8 a, which are provided through the first bulkhead plate a1 near its central axis. Fluid passing the vertically provided first communication bores 8 a flows down vertically and is received by the flared surface of the conical section 11 b of the conical member 11.
The conical member 11 is provided with grooves 12 on the surface of the conical section 11 b of the conical member 11. These grooves 12 are preferably provided in a plurality of elongated grooves with different depths rather than provided horizontally on the perimeter of the conical section 11 b.
On the other hand, a plurality of projecting lines 9 and grooves 10 are axially and alternately provided on the inner surface of the gas-liquid mixing chamber 7. The projecting lines 9 and the grooves 10 are both provided on the inner surface of the generator 2 and are stratified. The second communication bores 8 b are respectively angled outward towards their lower openings, ensuring that fluid passing therethrough flows down outward and is guided to the projecting lines 9 or the grooves 10.
The cross-sectional shape of the second bulkhead plate a2 is tapered downwardly from the inner surface of the generator 2 toward its central axis, and the lower end of the second bulkhead plate a2 is open and creating a funnel shape. Through this opening Ka, the gas-liquid mixing chamber 7 and the valve chest B communicate with each other.
A projecting line 9 is also provided on the upper surface of the second bulkhead plate a2, wherein the upper surface is facing the gas-liquid mixing chamber 7. This projecting line 9 is provided particularly on the top section of the second bulkhead plate a2, forming a groove 10 similar to the above-described grooves 10 between the projecting line 9 on the top section of the second bulkhead plate a2 and the lowest projecting line 9 on the inner surface of the gas-liquid mixing chamber 7.
In this manner, a turbulence generating mechanism (turbulence generating means) Z is constructed with features such as the projecting lines 9 and the grooves 10 on the inner surface of the generator 2 and on the second bulkhead plate a2 in the gas-liquid mixing chamber 7; and the conical section 11 b and the grooves 12 thereon.
It should be noted that the respective locations and sizes of the projecting lines 9 and the grooves 10 provided on the inner surface of the generator 2 and the second bulkhead plate a2 (turbulence generating mechanism Z), the diameter and taper angle of the conical section 11 b of the conical member 11, the depth of the grooves 12 on the conical section 11 b and the like are all freely configured according to, for example, the type, generation speed and pressure of generated nanofluid.
For example, the height of the projecting lines 9 and the depth of the grooves 10 and 12 may be both set to 5 mm (i.e., up to 10 mm height difference). Similarly, the internal volume of the gas-liquid mixing chamber 7, the respective numbers and diameters of the first and second communication bores 8 a and 8 b on the first bulkhead plate a1, the cross-sectional diameter of the generator 2 and the like are also freely configured according to, for example, the type, generation speed and pressure of generated nanofluid.
Provided on the upper surface of the second bulkhead plate a2 under its projecting line 9 is a polished surface with platinum chips attached thereon for ensuring high smoothness, and this smooth surface constructs a first smooth surface section Ha. Thus, the upper surface of the second bulkhead plate a2, except where the projecting line 9 is located, is formed to be an extremely smooth surface by the first smooth surface section Ha.
A platinum material was selected for its superior polishability; in general a stainless steel material used for the generator 2, and other metal materials are physically limited to achieve smooth-enough surfaces by polishing in order to configure a desirable channel width value as discussed below. In contrast, platinum materials allow for a nearly ultimate surface smoothness precision for forming the channel in desired sizes.
The opening Ka is the lower end of the first smooth surface section Ha and a stop valve body 15 is passed through this opening Ka. The stop valve body 15 consists of a rod section 15 a passed through the opening Ka of the second bulkhead plate a2 and a opening Kb provided along the central axis of the third bulkhead plate a3; a valve section 15 b provided integrally with and continuously to the rod section 15 a at the upper end thereof; and a stopper section 15 c provided integrally with and continuously to the rod section 15 a at the lower end thereof.
The diameter of the rod section 15 a of the stop valve body 15 is smaller than both the diameter of the opening Ka of the second bulkhead plate a2 and the diameter of the opening Kb of the third bulkhead plate a3. In addition, the dimensions of the stop valve body 15 are configured such that the valve section 15 b is positioned over the upper surface of the second bulkhead plate a2, and such that the stopper section 15 c is positioned inside the discharge space section C under the third bulkhead plate a3, therefore the valve section 15 b mounts over the angled upper surface of the second bulkhead plate a2, bearing the entire weight of the stop valve body 15.
Further, the perimeter of the valve section 15 b is tapered with the same angle as the taper angle of the upper surface of the second bulkhead plate a2, has a predetermined axial length (thickness), and is in close contact with the first smooth surface section Ha formed on the second bulkhead plate a2.
Polished and highly smoothened platinum chips are attached to the perimeter of the valve section 15 b, constructing a second smooth surface section Hb. As such, the second bulkhead plate a2 and the stop valve body 15 are in close contact with the first and second smooth surface sections Ha and Hb facing each other.
In practice, an extremely narrow gap is naturally formed between the first smooth surface section Ha of the second bulkhead plate a2 and the second smooth surface section Hb of the stop valve body 15. As previously mentioned, stainless steel and other metal materials in general have physical limitations to achieve smooth surfaces by polishing, creating a gap of several tens of μm in width between two smoothened surfaces made thereof no matter how closely they are attached to each other.
In contrast, when using platinum materials to form two extremely smoothened surface sections in close contact with each other, the gap between the surfaces may be minimized to the order of nanometer. Here, as shown in FIG. 1B, the gap (hereinafter referred to as “nano-outlet 20”) between the first and second smooth surface sections Ha and Hb, both made of the platinum material, may be narrowed down to a nano-scale width of about 0.2 μm (200 nm).
This stop valve body 15 can be separated from the main generator 2 unit, and as will be described later, when the generator 2 is disassembled to be cleaned, the stop valve body 15 is constructed such that when separated from the generator 2, the entire surface, which includes the surface of the valve section 15 b that forms one surface of the nano-outlet 20, can be cleaned. By periodically or infrequently performing disassembly and cleaning in this way, it is possible to avoid partial blocking of the nano-outlet 20 a due to a fluid component adhering to the surface of the nano-outlet 20 over time, as well as it is possible to prevent impurities or solid matter from mixing with the generated nanofluid.
On the other hand, a plurality of bores 16 are provided in the third bulkhead plate around the opening Kb through which the rod section 15 a of the stop valve body 15 passes, and the valve chest B and discharge space section C are connected by way of these bores 16. A plurality of pipes (external supply channels 41 a to 41 b) that are connected to external processing apparatuses 40 a to 40 c as shown in FIG. 2 are connected via the filtration mechanism F to the outlet 6 that is provided on the bottom end of the generator 2. The construction of the filtration mechanism F will be explained later.
In the nanofluid generating apparatus 1 that is constructed as described above, by driving the pressurization pump 4, pure water is directed from the water supply source S via the water purifying apparatus, air is directed from the air intake valve 21 via the bypass circuit R, and this pure water and air are supplied to the holding tank 3 in a pressurized state. The holding tank 3 has the function of stabilizing the ratio of gas to liquid and the pressure of the pressurized gas-liquid mixture fluid that is held.
The pressurized purified water-air mixture fluid, i.e., the gas-liquid mixture fluid stays in the holding tank 3 until its volume increases to a predetermined level inside the holding tank 3, which then opens the supply valve 22 provided at the inlet body 3 a. The pressurized gas-liquid mixture fluid with the predetermined relative ratio is supplied through the inlet 5 to the decomposition space section A, which is formed as the top partition inside the generator 2.
Once filling the decomposition space section A, the pressurized gas-liquid mixture fluid flows down the first communication bores 8 a and the second communication bores 8 b to be guided into the gas-liquid mixing chamber 7. In this manner, the decomposition space section A may supply and guide uniformly pressurized gas-liquid mixture fluid into the gas-liquid mixing chamber 7. Alternatively, the gas-liquid mixture fluid may be pressurized after being supplied into the gas-liquid mixing chamber 7.
The gas-liquid mixture fluid passing through the first communication bores 8 a falls down on and bounces off the upper surface of the conical section 11 b or the grooves 12 thereon of the conical section 11 b directly beneath the first communication bores 8 a. At this time, the bounce-off angle of gas-liquid mixture fluid droplets bounding off the conical section 11 b, and the bounce-off angle of the droplets bounding off the grooves 12 are different from each other.
Thus, after bouncing off the conical member 11 as described above, the droplets collide against the lower surface of the first bulkhead plate a1 at different positions, further rebounding with different angles. Due to the outward angles of the second communication bores 8 b, the pressurized gas-liquid mixture fluid passing through the bores 8 b falls down outwardly on and bounces off the projecting lines 9 or the grooves 10, which are axially provided on the inner surface of the gas-liquid mixing chamber 7.
The gas-liquid mixture fluid droplets colliding against the projecting lines 9 or the grooves 10 bounce off with different angles, further repeating many collisions against the first bulkhead plate a1, the conical member 11, other projecting lines 9 and grooves 10 and other components of the turbulence generating mechanism Z, while flowing downward.
Accordingly, the pressurized gas-liquid mixture fluid guided into the gas-liquid mixing chamber 7 scatters into random directions due to the internal shape of the turbulence generating mechanism Z inside the gas-liquid mixing chamber 7, and maintains its turbulent state. As the mixture liquid repeatedly collides against and bounces off the inner surface of the turbulence generating mechanism Z at different positions, the gas-liquid mixing and gas bubble miniaturization progress while under pressure.
Still pressurized, the gas-liquid mixture fluid in the turbulent state and forcibly mixed in the gas-liquid mixing chamber 7 is forced to pass through the nano-outlet 20, the gap between the first smooth surface section Hb on the second bulkhead plate a2 and the second smooth surface section Ha on the vb15 of the stop valve body 15.
After being forced to pass through the nano-outlet 20, the gas-liquid mixture fluid turns into nanofluid with a high nanobubble content and is supplied into the valve chest B. The size of the nanobubble-containing nanofluid droplets is about the same as the width of the nano-outlet 20, i.e., 0.2 μm (200 nm). More than 120,000 nanobubbles with 50 nm-90 nm diameter were verified in 1 ml of the nanofluid generated as above by measuring the nanofluid using a nanoparticle counter, Liquid-Borne Particle Sensor KS-17 (Rion Co., Ltd.). It should be noted that in the process of nanofluid generation, the fluid (purified water) itself becomes divided into nano-size clusters, drastically improving its liquid absorbency.
The nanofluid that was directed to the valve chest B is then gradually directed from the valve chest B through the plurality of bores 16 to the discharge space section C, and fills the discharge space section C. The discharge space section C temporarily holds the nanofluid and puts the nanofluid into a stabilized state, after which the discharge space section C supplies the nanofluid to a specified supply destination from the outlet 6. This discharge space section C has the function of a pressure reduction unit and storage tank that temporarily stores the nanofluid that is output in a pressurized state, reduces the pressure of the nanofluid until it is at atmospheric pressure, slows the speed of flow, and stabilizes the nanofluid. This pressure reduction unit or storage tank could also be independently provided on the outside of the outlet 6. Moreover, the volume and storage time of the storage tank are designed according to the use of the nanofluid, the applied pressure, type of gas and the like.
As described above, nanofluid containing nanobubbles with about 0.2 μm (200 nm) diameter may be stably generated from purified water and air using a simply-structured apparatus which is easy to use and allows to reduce its manufacturing cost.
As shown in FIG. 2, in order to select the generated nanofluid according to usage, this embodiment of the invention comprises: a filtration mechanism F that filters out nanofluid having a specified diameter from the nanofluid that is stabilized by the discharge space section C; a circulation channel for supplying nanofluid having a relatively large diameter that has been separated out by a primary filter F1 to the gas-liquid mixing chamber 7 via the water supply source S and holding tank 3; and supply channels 41 a, 41 b that respectively supply nanofluid that has passed through the primary and secondary filters F1, F2 to a plurality of external processing apparatuses 40 a, 40 b.
The filtration mechanism F removes nanofluids having a diameter that exceeds a reference diameter that is set based on the diameter of nano-sized elements (molecules, cells, etc.) of the object being processed, or the spacing between a plurality of elements, and comprises a plurality of filters F1, F2 for removing nanofluids of different sizes. For example, the primary filter F1 is set to separate out and remove nanofluids having a relatively large diameter on the scale of several hundred to 1000 nm, and the secondary filter F2 is set to separate out and remove nanofluids on the scale of 100 nm to several hundred nm. In this way it possible to select nanofluids according to a plurality of usages, and thus the generated nanofluids can be used without wasting any.
Moreover, nanofluid having a large diameter that was separated out by the primary filter F1 can be suitably used for water quality improvement of closed bodies of water, or for water for farmed fish and shellfish or for hydroponic vegetables and the like, however, in this embodiment, this nanofluid is supplied to the gas-liquid mixing chamber 7 via the circulation channel CR and the nanotization process is repeated. In other words, by reusing nanofluid for which nanotization was not sufficient as a gas-liquid mixture, it is possible to supply only nanofluid with a high degree of nanotization to external processing apparatuses 40 a, 40 b. Even when nanotization is not performed sufficiently, when compared with normal liquid and gas that are supplied from the water supply source S and air intake valve 21, the state of the mixture and the molecule diameter are in a more preferable state for the nanotization process, so by circulating and reusing this kind of nanofluid, it is possible to efficiently generate nanofluid having a microscopic diameter.
Furthermore, as shown in FIG. 3, the nanofluid generating apparatus 1 of this embodiment is constructed such that the generator 2 can be disassembled into a left and right member 2 a, 2 b, and comprises a junction section 50 that tightly fastens the ends of the members 2 a, 2 b together by bolts B and nuts N.
For example, in fields such as beverages like soft drinks and beer, substances such as liquid type drugs that are directly taken into or administered to the human body, and drugs or antiseptics for treatment of dermatosis such as atopic dermatitis, the manufacturing process is strictly controlled in terms of sanitation and prevention of contamination due to impurities. Therefore, when generating nanofluid to be used in fields such as these, it is necessary that the inside of the apparatus be cleaned frequently and that a high level of sanitation be maintained. In this embodiment, in order that the inside of the apparatus can be easily cleaned, the generator is constructed such that it can be separated and disassembled into left and right parts for cleaning. Particularly, there is a possibility that a fluid component will adhere over time to the nano-outlet 20 (nano channel) that is between the first smooth surface section Ha of the second bulkhead plate a2 of the gas-liquid mixing chamber 7 and the second smooth surface section Hb of the valve section 15 b of the stop valve body 15, and thus there is a possibility that the channel could become partially blocked, or that solid matter may mix into the nanofluid. Therefore, it is preferred that disassembly be possible along this nano-outlet 20 (nano channel) for cleaning.
On the other hand, the junction section 50 of each of the members 2 a, 2 b has lower mechanical strength than the non-junction section, so there is a possibility that the air tightness and sanitation will decrease due to degradation over time. Especially in this embodiment, nanofluid is generated by applying a pressure of 10 atm or greater, so it is also feasible that the strength of the junction section 50 will not be able to withstand the high pressure. Therefore, in this embodiment, as shown in the enlargement in FIG. 3B, construction is such that the material thickness of the area around the junction section 50 of the generator 2 is formed thicker than the non-junction section, and a ring-shaped reinforcement material 51 is wrapped around the outside of the generator 2 to maintain the strength.
In order to increase the tensile strength, the reinforcement material 51 is formed, for example, such that the end sections thereof are formed into a wedge shape or hook shape. By doing this, when generating nanofluid it is possible to maintain sufficient mechanical strength and withstand high pressure, as well as it is possible to perform disassembly easily when cleaning, and thoroughly clean the inside. It was omitted in the drawings and explanation, however, it is preferred that each of the channels and holding tank 3, the pressurization means 5, and filtration mechanism F be capable of being disassembled at an appropriate location and cleaned similar to the generator 2 described above, and that the strength of the junction section be strengthened when necessary.
(Variation)
It should be noted that the present invention is not limited to the above embodiment and may be embodied with various modifications made to its components without departing from the spirit and scope of the present invention. Thus, appropriate combinations of the plurality of components disclosed as in the above embodiment enables various further inventions.
For example, the holding tank 3 interposed between the pressurization pump 4 and the generator 2 may be omitted to supply the pressurized gas-liquid mixture fluid from the pressurization pump 4 and the air intake valve 21 directly to the generator 2.
Alternatively, pressurized liquid and pressurized gas may be separately supplied into the generator 2 for mixing as well as achieving the turbulent state therein. In this case, it takes a relatively long time (several tens of seconds to several minutes) until the pressure and gas-liquid relative ratio stabilize in the generator 2 after supplying the pressurized liquid and the pressurized gas separately into the generator 2, although once its contents are stabilized, this apparatus may continuously generate nanofluid as in the embodiment provided with the holding tank 3.
Although the above-described embodiment comprises the conical member 11 as an internal structure of the gas-liquid mixing chamber 7 along its central axis, and the projecting lines 9 and the grooves 10 axially and alternately provided on the inner surface of the generator 2, the present invention is not limited to this configuration and, for example, a plurality of plate bodies having guiding bores may be disposed with a predetermined interval, wherein positions of the guided bores may vary on each plate body.
The respective guiding bores in adjacent plate bodies do not align with one another, making these plate bodies so called “baffle plates” for the fluid to allow its gas-liquid mixing. Alternatively, mesh bodies with different fineness may be provided instead of the plate bodies to achieve similar operational advantage. However, the mesh bodies need to be rigid enough to resist a pressure applied by the gas-liquid mixture fluid, which is pressurized before guided into the gas-liquid mixing chamber 7. The key is to employ a structure which efficiently allows to generate a turbulent state of the gas-liquid mixture fluid in the gas-liquid mixing chamber 7.
Although the nano-outlet 20 in the above-disclosed embodiment is a nano-scale gap naturally formed between the first and second smooth surface sections Ha and Hb, which are in close contact with each other and made of platinum chips, other metal materials may be used in place of platinum if they allow a nano-scale outlet width with special polishing technologies or improved coating technologies.
Moreover, the fluid to be nanotized is not limited to pure water or air, and depending on the use, various fluids or gasses (for example, ozone, oxygen, etc.) can be used.
Furthermore, in the embodiment described above, the discharge space section C was provided as a pressure reduction unit and holding tank, however, it is also possible to provide a separate holding tank outside of the generator 2, and to house a mechanism inside this holding tank to reduce the pressure and rectify the nanofluid that is output from in a pressurized state.
(Example of an External Processing Apparatus)
Next, a cleaning apparatus 30 that uses nanofluid that is supplied from the nanofluid generating apparatus 1 to clean an object being processed will be explained as an example of an external processing apparatus 40 mentioned above.
FIG. 3 is a schematic drawing of a cleaning apparatus 30 that is connected to the nanofluid generating apparatus 1 via the supply channel 41 b, and to which microscopic nanofluid that has passed through the secondary filter F2 is supplied.
This cleaning apparatus 30 comprises a processing tank 31. This processing tank 31 is constructed such that it uses a fluid head, for example, to receive nanofluid from the nanofluid generating apparatus 1, and is located at a position lower than the nanofluid generating apparatus 1. An inlet 32 is provided in the bottom section of this processing tank 31, and this inlet 32 connects with the outlet of the filtration mechanism F of the nanofluid generating apparatus 1 via the supply channel 41 b.
When it is not possible to obtain this kind of fluid head due to installation space, it is possible to place the cleaning apparatus 30 close to the side of the nanofluid generating apparatus 1, and to provide a pump midway along the supply channel 41 b, which connects the outlet 6 of the nanofluid generating apparatus 1 with the inlet 32 of the cleaning apparatus 30, such that this pump supplies nanofluid from the nanofluid generating apparatus 1 to the cleaning apparatus 30.
A rectifying mechanism 33 is provided inside the processing tank 31 so that a plurality of horizontal or inclined plate sections thereof are located such that they face the inlet 32, and so that only some face each other.
This rectifying mechanism 33 performs the function of rectifying the nanofluid that is supplied from the inlet 32 and directing it to the center of the processing tank. In addition, the object W that is being processed is supported by a supporting mechanism (not shown in the figure) so that it is housed in the center on the inside of the processing tank 31 at a location that faces the rectification direction of the rectifying mechanism 33. Here, for example, the object W being processed is a semiconductor wafer (hereafter, simply referred to as a ‘wafer’), or the skin of a dermatosis patient.
The supporting mechanism supports a plurality of wafers W in a row with a small space between each, and transports these wafers W by freely moving them up or down between the inside of the processing tank 31 and outside of the processing tank 31. Naturally, when transporting the wafers W, the supporting mechanism secures the position of the wafers W and keeps them from moving. On the outside of the processing tank 31, the wafers W can be freely removed from the supporting mechanism, and construction is such that setting the wafers on the supporting mechanism can be performed easily.
An overflow tank 34 is provided around the entire outer surface on the upper end of the processing tank 31, and a drainage pipe 35 that is connected to a drainage unit (not shown in the figure) is connected to the bottom section of this overflow tank 34.
Nanofluid is continuously supplied to the processing tank 31 from the nanofluid generating apparatus 1 so that the processing tank 31 is constantly filled with nanofluid. Only the continuously supplied amount of nanofluid spills over as overflow from the processing tank 31 to the overflow tank 34, and is drained to the outside via the drainage pipe 35.
As the wafers W that are supported by the supporting mechanism are moved from the outside and become housed inside the processing tank 31, a large amount of nanofluid spills over from the processing tank 31 into the overflow tank 34, and this overflow tank 34 receives all of the overflow so that none of the nanofluid flows directly to the outside from the processing tank 31.
In the cleaning apparatus 30 that is constructed in this way, the wafers W that are supported by the supporting mechanism are moved into the processing tank 31. Nanofluid that contains nanobubbles has already been supplied to the processing tank 31 such that the processing tank 31 is full, so all of the wafers W are immersed in the fluid.
The nanofluid that contains nanobubbles is continuously directed from the outlet 6 of the nanofluid generating apparatus 1, through the supply channel 41 b and inlet 32 and into the processing tank 31. In the processing tank 31, the nanofluid is rectified by the rectifying mechanism 33 such that it is evenly directed at and concentrated on all of the wafers W that are supported by the supporting mechanism, and supplied for the wafer W cleaning process.
For example, even when a minute particle (impurity) is strongly adhered to a wafer W, the nanobubbles that are contained in the nanofluid enter in and become located between the wafer W and the particle and peel the particle from the wafer W. Similarly, all of the particles are forcibly peeled from the wafers W by the nanobubbles that are contained in the nanofluid, making it possible to maintain an extremely high level of efficiency for cleaning the wafers W.
The cleaning apparatus 30 comprises a supporting mechanism that moves a plurality of wafers W into and out of the processing tank 31, however, this supporting mechanism could also further improve the efficiency of cleaning the wafers W by having a function of rotating the wafers W or moving the wafers W back and forth inside the processing tank 31.
Furthermore, a rectifying mechanism 33 is provided inside the processing tank 31, however, the invention is not limited to this, and instead of a rectifying mechanism 33, or in addition to a rectifying mechanism 33, it is possible for the processing tank 31 to comprise a jet mechanism that forcibly shoots out nanofluid at the wafers W.
Moreover, instead of a processing tank 31, a so-called shower mechanism could be provided that simply showers the wafers W with nanofluid and exposes the wafers W in a spray of nanofluid for a specified period of time to clean the wafers W.
Also, an example of using wafers as the object W being processed was presented, however, the invention is not limited to this, and of course it is also possible to apply the invention to a cleaning apparatus for cleaning LCD glass boards, an etching apparatus and the like.

Claims

1. An apparatus for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprising:

a gas-liquid mixing chamber for forcibly mixing supplied gas and liquid by generating turbulence therein;

a pressurization means for applying pressure to the gas and liquid to be supplied to the gas-liquid mixing chamber;

a nano-outlet for discharging pressurized gas-liquid mixture fluid to outside of the gas-liquid mixing chamber to thereby generate nanofluid; and

a filter mechanism for removing nanofluid containing gas bubbles with diameter equal to or greater than a predetermined value from the generated nanofluid.

2. The apparatus of claim 1, further comprising:

a circulation channel for introducing part or all of the nanofluid removed by the filter mechanism into the gas-liquid mixing chamber for circulation.

3. The apparatus of claim 1, further comprising:

a storage tank for storing the nanofluid discharged from the nano-outlet.

4. The apparatus of claim 1, wherein

the filter mechanism is composed of a plurality of filter mechanisms respectively designed to remove nanofluid containing gas bubbles with different diameters, wherein the apparatus further comprises a supply channel for supplying at least part of the nanofluid removed by the plurality of filter mechanisms to an external apparatus.

5. The apparatus of claim 1, wherein

the filter mechanism removes nanofluid containing gas bubbles with diameters greater than a reference value determined based on diameters of micro-scale components (such as molecules or cells) of an object of treatment, or gap dimensions among a plurality of components,

wherein the apparatus further comprises a treatment water supply channel for supplying to a treatment apparatus the nanofluid which passed through the filter mechanism and contains gas bubbles with diameter equal to or smaller than the reference value, wherein the treatment apparatus treats the object by immersing the object in the nanofluid or exposing the object to nanofluid-sprayed atmosphere.

6. The apparatus of claim 1, further comprising:

a depressurizing means for reducing a pressure of the nanofluid discharged from the nano-outlet and supplying the depressurized nanofluid to the filter mechanism.

7. The apparatus of claim 1, wherein

some or all component members of the apparatus, including the gas-liquid mixing chamber, are disassembleable and cleanable, and when assembled, each of the disassembleable members is incorporated into the apparatus with a mechanical strength equivalent to or greater than that of non-disassembleable members of the apparatus.

8. The apparatus of claim 7, wherein

the nano-outlet is disassembleable along a nano-channel in communication with the gas-liquid mixing chamber.

9. An apparatus for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprising:

a circulation channel for introducing part or all of the generated nanofluid into the gas-liquid mixing chamber for circulation.

10. A method for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprising the steps of:

supplying gas and liquid to a gas-liquid mixing chamber;

with a pressurization means, pressurizing the gas and liquid before or after the step of supplying gas and liquid;

with a turbulence generating mechanism provided in the gas-liquid mixing chamber, forcibly mixing the supplied and pressurized gas and liquid in the gas-liquid mixing chamber by generating turbulence; and

discharging pressurized gas-liquid mixture fluid from a nano-outlet provided in an exit side of the gas-liquid mixing chamber, to outside of the gas-liquid mixing chamber to thereby generate nanofluid.

11. A method for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprising the steps of:

pressurizing liquid with a pressurization means and supplying the pressurized liquid to a gas-liquid mixing chamber;

drawing gas in with a pressure difference between the upstream and downstream of the pressurization means upon actuation thereof and introducing the gas into the liquid;

introducing pressurized gas-liquid mixture fluid into the gas-liquid mixing chamber, and generating turbulence in the gas-liquid mixture fluid by guiding the gas-liquid mixture fluid into repeated bouncing into random directions with a turbulence generating means provided in the gas-liquid mixing chamber; and

releasing the gas-liquid mixture fluid from a nano-outlet provided in an exit side of the gas-liquid mixing chamber, to thereby generate the nanofluid containing the nanobubbles.

12. The method as in claim 10, further comprising:

filtering with a filter mechanism to separate and remove nanofluid containing gas bubbles with diameter equal to or greater than a predetermined value from the generated nanofluid.

13. The method as in claim 11, further comprising: