CN103007792B - A kind of microchannel mixed method based on supercritical fluid - Google Patents
A kind of microchannel mixed method based on supercritical fluid Download PDFInfo
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- CN103007792B CN103007792B CN201210557306.8A CN201210557306A CN103007792B CN 103007792 B CN103007792 B CN 103007792B CN 201210557306 A CN201210557306 A CN 201210557306A CN 103007792 B CN103007792 B CN 103007792B
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Abstract
The invention discloses a kind of microchannel mixed method based on supercritical fluid.The present invention adopts and near critical fluids and thing to be mixed is sent into microchannel; Then the one-sided outside wall surface in microchannel heated or heat in relative both sides outside wall surface simultaneously; Fluid in microchannel reaches Supercritical Conditions, eddy generation disturbance, realizes effectively strengthening mixing.Method of the present invention only applies heat and produces stronger vortex disturbance effect in outside, and does not need not by the method such as design of external force or complicated microchannel, and can realize the mixing of good minute yardstick and the process of stirring, operation is simple and reliable, good mixing effect; And, the heating of pulsed cycle or continuous heating is adopted to produce stronger vortex disturbance in the inside of microchannel, thing to be mixed is driven fully to stir, avoiding conventional method manufacturing and designing the larger cost in complex passages, loading miniature scale electromagnetic field etc., the mixing higher than Common fluids thermal agitation intensity and mixing effect can be obtained simultaneously.
Description
Technical field
The invention belongs to field of micro electromechanical technology, relate to a kind of microchannel mixed method based on supercritical fluid.
Background technology
Along with the development of human civilization, at present biological, machinery, power and other many devices and equipment all present the feature of microminiaturization, bring that weight reduces, efficiency puies forward advantages of higher.Microchannel is ubiquitous a kind of device in these micro-systems, and in microchannel, reaches effective mixing be often very important, as the mixing etc. of fuel in the medicine mixing in biological medicine engineering, micropower system.But due to the reduction of size, in microscale channel, the convection current of gravity and fluid is suppressed, and the mixed effect produced by fluid convection is very small and weak.
The method strengthening mixing at present in microchannel has the stirring of micron order motor, small electric disturbance of magnetic field, thermal agitation, mechanical centrifugal rotation, complex passages structure naturally to mix.But these methods all need motion or rotary part, and making and the installation and operation of the parts of these minute yardsticks are consuming time, effort, and existence allows the number of disadvantages such as unreliable for a long time.And existing mixed method requires that the size of microchannel can not be too little, and hydraulic diameter is less than to the microchannel of less than 1 millimeter, mixed effect is undesirable.
Summary of the invention
For above problems of the prior art, the present invention proposes a kind of microchannel mixed method based on supercritical fluid, adopt the mode of wall heating, utilize near critical fluids in the change of thermophysical property stronger near critical point interval sensitivity, certain heat is applied in the outside of microchannel, thus cause the vortex disturbance that the supercritical fluid in microchannel is stronger, realize effectively strengthening mixing.
The object of the invention is to propose a kind of microchannel mixed method based on supercritical fluid.
Microchannel mixed method based on supercritical fluid of the present invention, comprises the following steps:
1) near critical fluids and thing to be mixed are sent into microchannel;
2) treat that flowing is stable, the outside wall surface of microchannel is heated;
3) elapsed time interval t after heating, the fluid in microchannel reaches Supercritical Conditions, eddy generation disturbance, realizes effectively strengthening mixing.
Wherein, the minimum hydraulic diameter of microchannel is 50 microns ~ 1 millimeter.
The material of microchannel can adopt the one in copper, stainless steel, aluminium and alloy.The internal face of microchannel is hydraulically smooth surface, hydraulically rough surface or the wall with certain lines.
Near critical fluids reaches Supercritical Conditions after heating in microchannel, can be liquid or gaseous state before entering microchannel.Near critical fluids is the one in water, carbon dioxide, hydrogen and nitrogen, ammonia, Freon series, propane and butane.
The state of thing to be mixed is gaseous state, liquid state or solid-state.
In step 1), control the speed of near critical fluids and thing to be mixed feeding microchannel, make its Reynolds number below 200.
In step 2) in, the outside wall surface heating of microchannel adopts the heating of Resistant heating, electrical bar, electric heating piece heating, film heating and heating bath to add the one of hankering.One-sided outside wall surface is adopted to heat or heat in relative both sides outside wall surface simultaneously to the outside wall surface heating of microchannel.The mode of heating of microchannel adopts the heating of pulsed cycle, or continuous heating; The pulsed cycle period interval time of heating is 5 milliseconds ~ 5 seconds; The duration of continuous heating is 5 milliseconds ~ 5 seconds.Apply heat intensity can with the thing to be mixed of actual size and supercritical fluid flow, minute yardstick number and change.
In step 3), time interval t meets,
wherein, L is the hydraulic diameter of microchannel, D
tbe thermal diffusion coefficient, γ is the adiabatic coefficent of fluid.
In step 3), the temperature T in microchannel meets, T/T
cvalue between 0.8 ~ 1.3, wherein, T
cfor the critical-temperature of fluid; Pressure P meets, P/P
cvalue between 0.8 ~ 2, wherein, P
cfor the critical pressure of fluid.
When the thing to be mixed of near critical fluids and minute yardstick together to enter in microchannel after flowing steadily, outside wall surface in microchannel applies the heating of pulsed cycle or continuous heating, fluid reaches Supercritical Conditions, in the boundary layer of supercritical fluid under these conditions, thermal conduction characteristic changes, thus causing stronger thermal agitation effect, this effect further develops with flowing, produces stronger vortex disturbance, drive thing to be mixed fully to stir, achieve and effectively strengthen mixing.Method of the present invention only applies heat and produces stronger vortex disturbance effect in outside, and does not need not by the method such as design of external force or complicated microchannel, and can realize the mixing of good minute yardstick and the process of stirring, operation is simple and reliable, good mixing effect; And the hydraulic diameter of microchannel can reach the miniature scale of 50 microns ~ 1 millimeter, also achieves good mixing in minute yardstick.
Advantage of the present invention:
The present invention utilizes the characteristic of near critical fluids, the heating of pulsed cycle or continuous heating is adopted to produce stronger vortex disturbance in the inside of microchannel, thing to be mixed is driven fully to stir, avoiding conventional method manufacturing and designing the larger cost in complex passages, loading miniature scale electromagnetic field etc., the mixing higher than Common fluids thermal agitation intensity and mixing effect can be obtained simultaneously.
Accompanying drawing explanation
Fig. 1 is the structural representation of the device of an embodiment of the microchannel mixed method based on supercritical fluid of the present invention;
Fig. 2 is the velocity profile of the mixing of the microchannel of an embodiment according to the microchannel mixed method based on supercritical fluid of the present invention.
Detailed description of the invention
Below in conjunction with accompanying drawing, by example, the present invention will be further described.
As shown in Figure 1, the device of the microchannel mixed method based on supercritical fluid of the present embodiment comprises: access road 11, preheater 12, fluid control valve 13, microchannel 14, heating film 15 and exit passageway 16 are formed.In the present embodiment, near critical fluids adopts carbon dioxide; The material of microchannel adopts copper; Mode of heating adopts film heating, and heating film 15 is close in the relative both sides outside wall surface of microchannel 14; Access road 11 and exit passageway 16 adopt stainless steel.
The temperature of near critical CO 2 fluid should be within the scope of 300K ~ 350K, and pressure should be in more than 7.38MPa.
The parameter specific as follows of the present embodiment:
Near critical CO 2 fluid is 304.2K in the temperature of access road, and pressure is 7.5MPa, and the Reynolds number of access road is 26.8;
Adopt continuous heating, the heat flow density of heating is 10000W/m
2, the duration is 5 seconds;
The length of microchannel is 5cm, and the hydraulic diameter in cross section is 333 μm, and wherein, width is 1mm, is highly 200 μm.
The microchannel mixed method based on supercritical fluid of the present embodiment, comprises the following steps:
1) nearly critical carbon dioxide fluid and thing to be mixed send into microchannel, coutroi velocity, and the Reynolds number of access road is 26.8;
2) treat that flowing is stable, adopt film heating to carry out continuous heating, the both sides outside wall surface relative to microchannel heats simultaneously, and the duration is 5 seconds;
3) elapsed time interval 0.1s after heating, reaches Supercritical Conditions, eddy generation disturbance, realizes effectively strengthening mixing.
After tested, the temperature of the supercritical fluid of exit passageway is 310K to the device of the present embodiment, and pressure change is less.Along with time variations, present stable tendency.Whole mixed process is divided into two stages: resting stage and vortex disturbance phase before heating.As shown in Figure 2, in the vortex disturbance phase, the inside of microchannel creates stronger vortex disturbance.Corresponding whirlpool is rounded, till extending to the internal face of microchannel; Whirling motion is with the height 200 μm of microchannel for diameter, and on the length direction of microchannel, the cycle occurs; Eddy current Peak Flow Rate can be reached for more than 0.1m/s, can realize sufficient mix and blend.
It is finally noted that, the object publicizing and implementing mode is to help to understand the present invention further, but it will be appreciated by those skilled in the art that: without departing from the spirit and scope of the invention and the appended claims, various substitutions and modifications are all possible.Therefore, the present invention should not be limited to the content disclosed in embodiment, and the scope that the scope of protection of present invention defines with claims is as the criterion.
Claims (10)
1. a microchannel mixed method, is characterized in that, described mixed method, comprises the following steps:
1) near critical fluids and thing to be mixed are sent into microchannel;
2) treat that flowing is stable, the outside wall surface of microchannel is heated;
3) elapsed time interval t after heating, the fluid in microchannel reaches Supercritical Conditions, eddy generation disturbance, realizes effectively strengthening mixing.
2. mixed method as claimed in claim 1, is characterized in that, the material of described microchannel adopts the one in copper, stainless steel, aluminium and alloy; The internal face of described microchannel is hydraulically smooth surface, hydraulically rough surface or the wall with certain lines.
3. mixed method as claimed in claim 1, it is characterized in that, described near critical fluids reaches Supercritical Conditions after heating in microchannel, can be liquid or gaseous state before entering microchannel; Near critical fluids is the one in water, carbon dioxide, hydrogen and nitrogen, ammonia, Freon series, propane and butane.
4. mixed method as claimed in claim 1, it is characterized in that, the state of described thing to be mixed is gaseous state, liquid state or solid-state.
5. mixed method as claimed in claim 1, is characterized in that, in step 1), controls the speed of near critical fluids and thing to be mixed feeding microchannel, makes its Reynolds number below 200.
6. mixed method as claimed in claim 1, is characterized in that, in step 2) in, the outside wall surface heating of microchannel adopts the heating of Resistant heating, electrical bar, electric heating piece heating, film heating and heating bath to add the one of hankering.
7. mixed method as claimed in claim 1, is characterized in that, in step 2) in, adopt one-sided outside wall surface to heat or heat in relative both sides outside wall surface simultaneously to the outside wall surface heating of microchannel; The mode of heating of microchannel adopts the heating of pulsed cycle, or continuous heating; The pulsed cycle period interval time of heating is 5 milliseconds ~ 5 seconds; The duration of continuous heating is 5 milliseconds ~ 5 seconds.
8. mixed method as claimed in claim 1, is characterized in that, in step 3), time interval t meets,
wherein, L is the hydraulic diameter of microchannel, D
tbe thermal diffusion coefficient, γ is the adiabatic coefficent of fluid.
9. mixed method as claimed in claim 1, is characterized in that, in step 3), the temperature T in microchannel meets, T/T
cvalue between 0.8 ~ 1.3, wherein, T
cfor the critical-temperature of fluid; Pressure P meets, P/P
cvalue between 0.8 ~ 2, wherein, P
cfor the critical pressure of fluid.
10. mixed method as claimed in claim 1, it is characterized in that, the minimum hydraulic diameter of microchannel is 50 microns ~ 1 millimeter.
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| CN1537029A (en) * | 2001-05-07 | 2004-10-13 | 环球油品公司 | Apparatus for mixing and reacting at least tow fluids |
| CN101712557A (en) * | 2008-09-30 | 2010-05-26 | Tdk株式会社 | Method for synthesizing powder and electronic component manufacturing mehtod |
| CN102000518A (en) * | 2010-09-27 | 2011-04-06 | 华北电力大学 | Micro mixing system of pulsating flow driven by micro bubble pump loop |
| GB2475300A (en) * | 2009-11-13 | 2011-05-18 | Alan Finlay | A microengineered supercritical fluid chromatography (SFC) system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20080004194A1 (en) * | 2002-09-24 | 2008-01-03 | Air Products And Chemicals, Inc. | Processing of semiconductor components with dense processing fluids |
| US20070214712A1 (en) * | 2006-03-20 | 2007-09-20 | American Beef Processing, Llc | Bio-diesel manufacture with a micro-reactor |
| EP2386562A4 (en) * | 2009-01-07 | 2012-08-08 | Nat Inst Of Advanced Ind Scien | Halogen-substituted saccharide, method for producing same, reaction composition of same and device for producing same |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1537029A (en) * | 2001-05-07 | 2004-10-13 | 环球油品公司 | Apparatus for mixing and reacting at least tow fluids |
| CN101712557A (en) * | 2008-09-30 | 2010-05-26 | Tdk株式会社 | Method for synthesizing powder and electronic component manufacturing mehtod |
| GB2475300A (en) * | 2009-11-13 | 2011-05-18 | Alan Finlay | A microengineered supercritical fluid chromatography (SFC) system |
| CN102000518A (en) * | 2010-09-27 | 2011-04-06 | 华北电力大学 | Micro mixing system of pulsating flow driven by micro bubble pump loop |
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| "超临界二氧化碳在突扩管中对流换热的流动特性研究";邓毕力等;《工程热物理学报》;20110831;第32卷(第8期);第1393-1395页 * |
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