US20100010422A1

US20100010422A1 - Nanofluid Production Apparatus and Method

Info

Publication number: US20100010422A1
Application number: US11/992,359
Authority: US
Inventors: Sadatoshi Watanabe
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-09-23
Filing date: 2006-09-22
Publication date: 2010-01-14
Also published as: JP2008246486A; WO2007034913A1; JPWO2007034580A1; WO2007034580A1; JPWO2007034913A1; JPWO2007034912A1; WO2007034912A1; US8726918B2; US20090293920A1; JP4222572B2; US20090273103A1

Abstract

The object of the invention is to provide an apparatus and a method for generating a large amount of nanofluid continuously and stably with a relatively simple, inexpensive and easy-to-use structure, and for efficiently performing an intra-apparatus cleaning operation to substantially reduce the nanofluid manufacturing cost.

A nanofluid generating apparatus 1 for generating nanofluid containing nanobubbles, wherein the nanobubbles are gas bubbles with diameter less than 1 μm, comprises a gas-liquid mixing chamber 7, comprising a turbulence generating mechanism for forcibly mixing supplied gas and liquid by generating turbulence, and a nano-outlet 20 for discharging the gas-liquid mixture fluid to outside of the gas-liquid mixing chamber to generate nanofluid; a gas-liquid supply apparatus 21, 23, . . . for supplying gas and liquid to the gas-liquid mixing chamber 7; a pressurization pump for applying pressure to the gas and liquid; and a control unit CR for controlling operations of the pressurization pump 4 and the gas-liquid supply apparatus. The control unit CR controls the gas-liquid supply apparatus and the pressurization pump 4 to switch between a nanofluid generation mode and a cleaning mode for cleaning the inside of the gas-liquid mixing chamber 7.

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.

THE 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.
In the meantime, when using nanofluid for processed food products such as beverages, or medicinal products, it is necessary to prevent impurity contamination by maintaining a high level of hygiene. In order to achieve this, the inside of the apparatus needs to be periodically sterilized, disinfected or cleaned (hereafter, collectively referred to as “cleaned”). Such cleaning work is generally carried out by immersing each disassembled part of the apparatus separately from other parts in a cleaning solution, or applying the cleaning solution to the parts, during which work the nanofluid production needs to be deactivated, resulting in higher manufacturing costs.

SUMMARY OF THE INVENTION

In order to address the above challenges, the objective of the present invention is to provide an apparatus and a method for generating nanofluid, which apparatus has a relatively simple and inexpensive structure, is easy to use, and capable of generating a large amount of nanofluid continuously and stably, and substantially reducing the manufacturing cost by efficient cleaning.
In order to achieve the above object, according to a first principal 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, comprising: a turbulence generating mechanism for forcibly mixing supplied gas and liquid by generating turbulence; and a nano-outlet for discharging the gas-liquid mixture fluid to outside of the gas-liquid mixing chamber to generate nanofluid; a gas-liquid supply apparatus for supplying gas and liquid into the gas-liquid mixing chamber through a supply channel in communication with the gas-liquid mixing chamber; a pressurization means for applying pressure to the gas and liquid to be supplied to the gas-liquid mixing chamber; and a control section for controlling operations of the pressurization means and the gas-liquid supply apparatus, wherein the control section controls at least one of the gas-liquid supply apparatus and the pressurization means to switch between a nanofluid generation mode and a cleaning mode for sterilizing, disinfecting or cleaning (hereafter, collectively referred to as “cleaning”) the inside of the gas-liquid mixing chamber and channels in communication with the gas-liquid mixing chamber.
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.
In addition, the control section is adapted to between the cleaning mode during which gas and liquid for cleaning are supplied into the apparatus, and the nanofluid generation mode by activating or deactivating the pressurization means and gas-liquid supply means. In this case, during the cleaning mode, the control section preferably controls the pressurization means such that a pressure in the gas-liquid mixing chamber is lower than the atmospheric pressure or a pressure applied during the nanofluid generation mode, and simultaneously controls the gas-liquid supply apparatus such that the gas-liquid supply apparatus supplies gas and/or liquid for cleaning into the gas-liquid mixing chamber.
In this manner, any internal areas in contact with the gas-liquid mixture fluid during the nanofluid generation mode may be thoroughly cleaned, and the nanofluid generation and cleaning modes may be instantaneously switched to each other, allowing to minimize the time for preparing for the cleaning and time for returning to the generation mode to thereby improve overall manufacturing efficiency. This further enables to reduce a nanofluid manufacturing cost.
Also by utilizing the nanofluid generating apparatus provided with the above structure, there may be provided a beverage generation apparatus with a simple structure capable of stably producing a beverage containing nanobubbles. Beverages containing nanobubbles offer unique sensation and taste by acting on cells in the human tongue surface (taste buds, or caliculus gustatorius) and throat internal wall, and retain their quality with nanobubbles freely floating inside the fluid over several months to reduce the change in quality over time (e.g., degassing in beer and carbonated beverages). Freely floating in the beverages for a long period of time, nanobubbles provide a secondary effect to, for example, facilitate wine maturation.
Moreover, by utilizing the nanofluid generating apparatus provided with the above structure, there may be provided a therapeutic fluid generating apparatus with a simple structure capable of stably producing therapeutic fluid (a drug) containing nanobubbles. Liquid-type drugs containing fine nanobubbles are capable of entering gaps in, and acting directly on cells and the like, and are expected to provide efficacy with a small dosage. Also for patients with various allergic dermatosis including atopic dermatitis, treatment or cleaning with anti-irritant drugs or purified water may be provided to reduce loads on patients such as side effects and facilitate their treatment.
When an ozonizer is provided as a cleaning fluid generating means, ozone generated by the ozonizer may clean the inside of the nanofluid generating apparatus during the cleaning mode, and ozone-containing nanofluid may be generated during the nanofluid generation mode. Such nanofluid containing nano-sale ozone may offer, for example, a superior sterilization effect for an extended period. On the other hand, an ozone filter is preferably installed around the nanofluid generating apparatus or in the vicinity of the nano-outlet to collect ozone present in an excess amount or ozone used for cleaning due to known direct effects of a large quantity of ozone on human health, such as causing eye pain, headache and breathing disorder. In addition, different amounts of ozone are preferably generated during the nanofluid generation mode and during the cleaning mode.
According to a second principal 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: with a gas-liquid supply apparatus, supplying gas and liquid into a gas-liquid mixing chamber comprising a turbulence generating mechanism and a nano-outlet; with a pressurization means, pressurizing the gas and liquid to be supplied to the gas-liquid mixing chamber; with a turbulence generating mechanism, forcibly mixing the gas and liquid supplied into the gas-liquid mixing chamber by generating turbulence; with a nano-outlet, discharging the gas-liquid mixture fluid under pressure to outside of the gas-liquid mixing chamber to generate nanofluid; and with the control section, controlling at least one of the gas-liquid supply apparatus and the pressurization means to perform sterilizing, disinfecting or cleaning (hereafter, collectively referred to as “cleaning”) the inside of the gas-liquid mixing chamber and channels in communication with the gas-liquid mixing chamber.
According to such a configuration, nanofluid generation method may be provided in a preferred manner by utilizing the nanofluid generating apparatus according to the first principal aspect described above.
According to the present invention, a large amount of nanofluid may be generated continuously and stably with a relatively simple, inexpensive and easy-to-use structure, providing an effect to substantially reduce the nanofluid manufacturing cost. In addition, the nanofluid generating apparatus of the present invention allows to ensure easy and fast intra-apparatus cleaning, capable of providing nanofluid even in the applications requiring a high level of hygiene, and improving the overall efficiency of nanofluid production including the cleaning process to thereby reduce the nanofluid manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(A) is a schematic view of a nanofluid generating apparatus according to an embodiment of the present invention, and

FIG. 1(B) is an enlarged fragmentary view of the nanofluid generating apparatus; and

FIG. 2 is a timing diagram showing a control flow of a control unit.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below based on the accompanying drawings.
FIG. 1(A) is a schematic cross-sectional view of a nanofluid generating apparatus 1 according to one embodiment of the present invention; FIG. 1(B) is a fragmentary sectional view showing an enlarged key portion M, which is circled in FIG. 1(A); and FIG. 2 is a timing diagram showing a control flow by a control unit.
The nanofluid generating apparatus 1 is composed of a generator 2, a holding tank 3, a pressurization pump (pressurization means) 4, a piping H in communication with the generator 2 from a water supply source through the pressurization pump 4 and the holding tank 3, an ozonizer O for generating ozone, a control unit (control section) CR for switching and controlling a nanofluid generation mode and an intra-apparatus cleaning mode, a ozone filter F for collecting ozone, and a cleaning unit WS for cleaning the inside of the apparatus.
A water purifying apparatus 23 is provided on the piping H between the water supply source S and the pressurization pump 4 for purifying water received from the water supply source S and supplying the purified water to the pressurization pump 4. The pressurization pump 4 may withdraw purified water from the water purifying apparatus 23, pressurize the purified water under 13-15 atm (13-15 times the atmospheric pressure), and send the pressurized purified water to the holding tank 3.
A by pass circuit R branches off from the piping H upstream and downstream of the pressurization pump 4. The by pass circuit R is provided with an air intake valve (air inlet means) 21, which is a check valve for introducing the external air into the by pass circuit R by being opened upon actuation of the pressurization pump 4.
The ozonizer O is disposed downstream of the pressurization pump 4. In the nanofluid generation mode, the ozonizer O may generate an ozone-containing nanofluid by supplying ozone into the holding tank 3 together with the external air from the air intake valve 21. Also in the cleaning mode, the ozonizer O generates ozone for cleaning the inside of the apparatus. Note that this ozonizer O may be disposed in parallel with the air intake valve 21 for selectively mixing in the external air and/or ozone.
In the present embodiment, a cleaning fluid supply apparatus WA is provided for supplying cleaning fluid to the pressurization pump 4 in the cleaning mode. The cleaning water from this cleaning fluid supply apparatus WA and the purified water from the water purifying apparatus 23 are preferentially supplied using a three-way valve. The cleaning fluid supply apparatus WA may be configured to comprise a storage tank for storing the cleaning fluid which is generated separately, or may be configured to generate the cleaning fluid by adding cleaning agent component to the water supplied from a water supply source (not shown).
A gas-liquid supply apparatus comprises the water purifying apparatus 23, the cleaning fluid supply apparatus WA, the air intake valve 21 and the ozonizer O. The control unit CR controls the gas-liquid supply apparatus, the three-way valve and the pressurization pump 4 to thereby switch between the nanofluid generation mode and the intra-apparatus cleaning mode.
Specifically, in the nanofluid generation mode, when the control unit CR actuates the pressurization pump 4 and the ozonizer O, a pressure difference is created in the piping H between the upstream and downstream of the pressurization pump 4 to allow the air (external air) introduced from the air intake valve 21, together with the ozone generated by the ozonizer O, to mix into the purified water sent under pressure by the pressurization pump 4, and the mixture is supplied into the holding tank 3.
Whereas in the cleaning mode, the control unit CR actuates the cleaning fluid supply apparatus WA and the ozonizer O, and simultaneously switches the three-way valve to a cleaning position to thereby supply gas-liquid mixture fluid of the cleaning fluid and the ozone to the holding tank 3. During this cleaning mode, the ozonizer O is controlled so that more ozone is generated than during the nanofluid generation mode. Types of the cleaning fluid, ozone contents, and the like are adjusted according to, for example, a type of nanofluid generated and a nanofluid generation capacity.
If the pressurization capacity of the pressurization pump 4 is 13-15 atm during the nanofluid generation, the air intake amount from the air intake valve 21 is set to about 1-3 liters per minute. Also in the cleaning mode, the gas-liquid mixture fluid is pressurized under 2-5 atm.
The holding tank 3 would store therein pressurized fluid (e.g., purified water and cleaning fluid) and gas (e.g., air and ozone) in a predetermined ratio, and the storage capacity of the holding tank 3 is changed according to, for example, the type of nanofluid generated and the nanofluid generation capacity 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 a cylindrical body with its central axis extending vertically, and is formed of a material with superior pressure resistance and water resistance such as stainless steel. Both top and bottom surfaces of the generator 2 are closed to complete; the top surface is provided with an inlet 5 and the bottom surface is provided with an outlet 6.
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 Hb.
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 Hb 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 Ha. 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. 1(B), 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).
In the third bulkhead plate a3, a plurality of bores (through-holes) 16 are provided around the opening Kb, through which the rod section 15 a of the stop valve body 15 passes, allowing the valve chest B and the discharge space section C to communicate with each other. The outlet 6, provided at the bottom of the generator 2, is adapted to connect with a piping in communication with an external processing apparatus (not shown).
When generating nanofluid using the nanofluid generating apparatus 1 constructed as above, the control unit CR activates the pressurization pump 4, the ozonizer O and the water purifying apparatus 23, and simultaneously switches (maintains) the three-way valve to a nanofluid-generation position, as shown in a timing diagram of FIG. 2. In this manner, purified water is guided to the pressurization pump 4; the air from the air intake valve 21 and the ozone generated by the ozonizer O are guided through the by pass circuit R and the purified water, air and ozone are pressurized and supplied to the holding tank 3. The holding tank 3 has a function to stabilize, for example, the gas-liquid relative ratio and the pressure applied the gas-liquid mixture fluid collected and stored in the holding tank 3.
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 guided into the valve chest B subsequently flows down through the plurality of bores 16 into the discharge space section C to fill the space. The discharge space section C collets and stabilizes the nanofluid and supplies it from the outlet 6 to a predetermined destination. This discharge space section C has a function to temporarily store the pressurized nanofluid discharged from the valve chest B, depressurize the nanofluid to the atmospheric pressure, and slows down the flow to stabilize the nanofluid. Alternatively, a depressurizing section and/or a holding tank may be independently provided outside of the outlet 6. Also, the internal volume and residence time of the holding tank is designed according to, for example, the usage of the nanofluid, the pressure applied to the nanofluid and the type of the gas-liquid.
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.
When cleaning the above apparatus after using it to generate nanofluid for a period of time, the control unit CR switches each component from the “nanofluid generation mode” to the “cleaning mode” as shown in FIG. 2. This mode switching may be performed automatically or regularly depending on, for example, the time or amount of the nanofluid generation, or may be performed manually by an operator. Moreover, the inside of the apparatus may be monitored by a flow sensor or the like so that the apparatus may be automatically switched to the cleaning mode when, for example, a reference value is exceeded.
In such a cleaning mode, the control unit CR first deactivates the pressurization pump 4, the water purifying apparatus 23 and the ozonizer O, and waits for the gas-liquid mixture fluid to be discharged from the apparatus. At this time, only the pressurization pump 4 may be activated to facilitate the discharge.
After standing by for a predetermined time, the control unit CR activates the pressurization pump 4, the cleaning fluid supply apparatus WA and the ozonizer O, and switches the three-way valve to the cleaning position. This initiates the cleaning mode. At this point, the pressurization pump 4 is set to about 2-5 atm, which is lower than during the nanofluid generation mode, but higher than the atmospheric pressure. This ensures efficient removal of fluid components and the like from the surface of the grooves 10 and nano-outlet 20, while reducing the load to the entire apparatus including the pressurization pump 4. Additionally, the ozonizer O preferably generates more ozone than during the nanofluid generation mode to thereby enhance the cleaning effect. On the other hand, the ozone filter F and an ozone sensor (not shown) are preferably installed, for example, around the outlet 6 in order to prevent degradation of a workplace environment due to known direct effects of ozone in large quantity on human health, such as causing headache and pulmonary edema. Furthermore, during the cleaning mode, the supply valve 22 at the bottom of the holding tank 3 may be opened at all times since there is not need to uniformly mix the gas and liquid.
After continuing such a cleaning mode for a predetermined period of time, the control unit CR deactivates the pressurization pump 4, the cleaning fluid supply apparatus WA and the ozonizer O to end the cleaning mode. When subsequently starting the nanofluid generation mode, the control unit CR switches each component to the nanofluid generation mode as discussed above. Note that the duration of the cleaning mode is to be adjusted according to, for example, the usage of the nanofluid, the type of the gas-liquid and the internal volume of the generator 2.
As discussed above, the present embodiment allows continuous and instantaneous switching between the nanofluid generation mode and the cleaning mode inside the nanofluid generating apparatus 1. This enables to minimize the time for preparing for the intra-apparatus cleaning and time for returning to the nanofluid generation mode to thereby improve overall efficiency of the nanofluid generation process and reduce the nanofluid manufacturing cost.
For example, beverages such as soft drinks and beer, substances such as liquid-type drugs which are directly ingested or administered into human bodies, drugs or antiseptic solutions for treating dermatosis such as atopic dermatitis, or substances such as lotions and shampoo which directly contact with human bodies are strictly controlled for maintaining hygiene during their manufacturing processes and for preventing impurity contamination. Accordingly, when generating nanofluid used in areas manufacturing such products, articles or substances, it is essential to maintain a high level of hygiene by frequently cleaning the inside of the nanofluid generating apparatus. Application of the nanofluid generating apparatus 1 of the present embodiment to such areas allows to maintain the hygiene level and improve generation efficiency.
When circulating impurity-containing fluid as in water quality improvement in closed bodies of water, gradual accumulation of micro-sized impurities in the nanofluid generating apparatus cannot be prevented even with various filters provided in the circulation channels. Even for such an application, the nanofluid generating apparatus of the present embodiment may be preferably utilized to dramatically increase the efficiency of the water quality improvement by allowing continuous switching between the nanofluid generation mode (water quality improvement mode) and the intra-apparatus cleaning mode without having to disassemble the apparatus for its cleaning.

Variation Example

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.

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, having: a turbulence generating mechanism for forcibly mixing supplied gas and liquid by generating turbulence, and a nano-outlet for discharging the gas-liquid mixture fluid to outside of the gas-liquid mixing chamber to generate nanofluid;

a gas-liquid supply apparatus for supplying gas and liquid into the gas-liquid mixing chamber through a supply channel in communication with the gas-liquid mixing chamber;

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

a control section for controlling operations of the pressurization means and the gas-liquid supply apparatus,

wherein the control section controls at least one of the gas-liquid supply apparatus and the pressurization means to switch between a nanofluid generation mode and a cleaning mode for sterilizing, disinfecting or cleaning (hereafter, collectively referred to as “cleaning”) the inside of the gas-liquid mixing chamber and channels in communication with the gas-liquid mixing chamber.

2. The apparatus of claim 1, wherein

during the cleaning mode, the control section controls the pressurization means such that a pressure in the gas-liquid mixing chamber is lower than the atmospheric pressure or a pressure applied during the nanofluid generation mode, and simultaneously controls the gas-liquid supply apparatus such that the gas-liquid supply apparatus supplies gas and/or liquid for cleaning into the gas-liquid mixing chamber.

3. The apparatus of claim 2, wherein

the gas-liquid supply apparatus comprises a cleaning fluid generating means for generating gas and/or liquid for cleaning during the cleaning mode.

4. The apparatus of claim 3, wherein

the cleaning fluid generating means is an ozonizer for generating ozone.

5. The apparatus of claim 4, wherein

the control section activates the ozonizer during the nanofluid generation mode as well to generate nanofluid containing ozone, and simultaneously controls the ozonizer such that different amounts of ozone are generated during the nanofluid generation mode and during the cleaning mode.

6. The apparatus of claim 4, further comprising:

an ozone filter for collecting the ozone used for cleaning the inside of the gas-liquid mixing chamber.

7. The apparatus of claim 1, wherein the apparatus is a beverage generating apparatus, wherein the gas-liquid supply apparatus supplies gas and liquid which are raw material components of a beverage into the gas-liquid mixing chamber to generate the beverage containing nanobubbles.

8. The apparatus of claim 1, wherein the apparatus is a therapeutic fluid generating apparatus, wherein the gas-liquid supply apparatus supplies gas and liquid for preventing or treating dermatosis into the gas-liquid mixing chamber to generate therapeutic fluid containing nanobubbles.

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

with a gas-liquid supply apparatus, supplying gas and liquid into a gas-liquid mixing chamber comprising a turbulence generating mechanism and a nano-outlet;

with a pressurization means, pressurizing the gas and liquid to be supplied to the gas-liquid mixing chamber;

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

with a nano-outlet, discharging the gas-liquid mixture fluid under pressure to outside of the gas-liquid mixing chamber to generate nanofluid; and

with the control section, controlling at least one of the gas-liquid supply apparatus and the pressurization means to perform sterilizing, disinfecting or cleaning (hereafter, collectively referred to as “cleaning”) the inside of the gas-liquid mixing chamber and channels in communication with the gas-liquid mixing chamber.