CN103712896A - Method for determining nano-fluid suspension stability - Google Patents
Method for determining nano-fluid suspension stability Download PDFInfo
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- CN103712896A CN103712896A CN201310588963.3A CN201310588963A CN103712896A CN 103712896 A CN103712896 A CN 103712896A CN 201310588963 A CN201310588963 A CN 201310588963A CN 103712896 A CN103712896 A CN 103712896A
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Abstract
A disclosed method for determining nano-fluid suspension stability comprises: on the basis of the relationship of particle mass fraction and conductivity of an electrolyte fluid suspension in Maxwell electromagnetic theory, taking a nano-fluid as a mixture same to an electrolyte solution, taking the base fluid of the nano-fluid as the conductor and taking nano-particles in the nano-fluid as small spheres distributed in the conductor, so as to establish a model; measuring the conductivity of various nano-fluids with known mass fraction, fitting to obtain a relation expression between the conductivity of nano-fluids and mass fraction of nano-particles contained in the corresponding nano-fluids; and measuring the any-moment conductivity of a nano-fluid of which the suspension stability is to be determined, according to the fit relation expression of nano-fluid conductivity and mass fraction, obtaining the mass fraction of the nano-fluid of which the suspension stability is to be determined, and determining the stability of the nano-fluid of which the suspension stability is to be determined. The determination method is simple and easy to realize, can help to realize quantitative analysis and is not restricted by particle concentration and quantity.
Description
Technical field
The present invention relates to physics technology field, particularly relate to and a kind ofly utilize in Maxwell's electromagnetic theory the relation between mass particle mark and conductivity in electrolyte suspending liquid to set up model, judge the method for nano-fluid suspension stability.
Background technology
Nano-fluid is in liquid, to add nano-scale particle with ratio in some way and a kind of heat-exchange working medium of forming.Nano-fluid can not only significantly improve the coefficient of heat conductivity of traditional heat transferring medium, but also can improve coefficient of diffusion, and therefore, nano-fluid has vital role aspect heat and mass transfer enhancement.
On the one hand, nano particle is ceaselessly done irregular Brownian movement, overcomes the effect of gravity and keeps being suspended in base fluid; On the other hand, the suction-operated of this ceaselessly Brownian movement and particle surface makes again nano particle in base fluid, be easy to reunite, and generates precipitation.Conventionally adopt methods such as adding spreading agent or surfactant, adjusting pH value and sonic oscillation to improve the stability of nano-fluid.However, due to reasons such as density, character of surface, nano particle still can sedimentation.The sedimentation meeting of nano particle affects heat transfer property and its mobility in equipment of nano-fluid itself, and serious can lose the performance characteristic of nano-fluid.So judge that the suspension stability of nano-fluid seems particularly important.
The method that is used for that this dispersion stability of nano-fluid is evaluated mainly contains several below: sedimentation, Zeta potential method, fractal method, particle diameter distribution and absorption photometry etc.But these methods all have certain limitation, as settling methods cannot carry out quantitative test, spectrophotometer method is only applicable to measuring the more shallow suspending liquid of color, and particle diameter distribution can only observe a few granules, quantitatively not representative, other two kinds of methods are more complicated again.
Summary of the invention
The object of the invention is for the technological deficiency existing in prior art, and provide a kind of method simple, the method for the judgement nano-fluid suspension stability of easily realizing.
For realizing the technical scheme that object of the present invention adopts, be:
A method of judging nano-fluid suspension stability, comprises the steps:
(1) according to the relation between mass particle mark and conductivity in Maxwell's electromagnetic theory electrolyte suspending liquid, regard nano-fluid as potpourri that same electrolyte solution is the same, the base fluid of take in nano-fluid is conductor, the nano particle of take in described nano-fluid, as interspersing among the bead in conductor, is set up model; The Conductivity Calculation formula of known quality mark nano-fluid is:
In formula (1): σ
mconductivity for the nano-fluid of known quality mark; σ
1conductivity for base fluid; σ
2conductivity for nano particle; φ is the massfraction of nano particle;
(2) measure the conductivity of the nano-fluid of various known quality marks, according to formula (1), obtain the massfraction of nano-fluid and the relation between conductivity, matching obtains the relational expression between the massfraction of contained nano particle in nano-fluid conductivity and nano-fluid;
(3) measure the conductivity of the nano-fluid of arbitrary moment suspension stability to be determined, the nano-fluid conductivity obtaining according to matching and the relational expression between massfraction, calculate the massfraction of the nano-fluid of suspension stability to be determined; According to gained massfraction, judge the stability of the nano-fluid of suspension stability to be determined.
The nano-fluid conductivity that matching obtains and the relational expression between massfraction are:
σ＝1.36667+201.2φ （2）
In formula (2): the conductivity that σ is nano-fluid; φ is the massfraction of nano particle.
Before the conductivity of the conductivity of measurement known quality mark nano-fluid and the nano-fluid of suspension stability to be determined, need elimination precipitation.
Measuring process is carried out at 25 ℃ of constant room temperatures.
Nano particle in the nano-fluid of known quality mark and the nano-fluid of suspension stability to be determined is spherical or class is spherical.
Measure conductivity and use conductivity meter.
Compared with prior art, the invention has the beneficial effects as follows:
1, the relation of method of the present invention based on electrolyte solution conductivity in Maxwell's electromagnetic theory and mass particle mark, nano-fluid is regarded as to the potpourri that is similar to electrolyte solution, set up scale model, by measuring the conductivity of different quality mark nano-fluid, simulate the relational expression between nano-fluid conductivity and massfraction.Utilize this relational expression, measure the conductivity of the nano-fluid of arbitrary moment elimination precipitation, can calculate the massfraction of nano-fluid, and then the suspension stability of judgement nano-fluid.The present invention judges that the method for nano-fluid suspension stability is simple, easily realizes.
2, the inventive method and simple to operate, can realize quantitative test, and is not subject to granule density and number quantitative limitation.
Accompanying drawing explanation
Figure 1 shows that the present invention judges the schematic diagram of the method equipment therefor of nano-fluid suspension stability;
Figure 2 shows that the resulting result of settling methods.
In figure: 1.2401-M conductance electrode, 2.MP522 type Accurate pH/conductivity meter, 3. computing machine.
Embodiment
Below in conjunction with specific embodiment, the present invention is described in further detail.
Maxwell proposes: a kind of conductivity is σ
1conductor, the inside some conductivity that are scattered here and there are σ
2bead, the ratio of the volume of all beads and the volume of whole potpourri is Φ, the radius of bead should be more much smaller than the distance between bead, Φ must be a very little number, can obtain the conductivityσ of potpourri
mformula be:
(1) when nano particle is spherical or class is spherical, distance between the radius ratio nano particle of the nano particle in nano-fluid is little a lot, therefore, nano-fluid is similar to a kind of potpourri of electrolyte solution, set up scale model, be base fluid as a kind of conductor, nano particle is the bead interspersing among in conductor.Above-mentioned formula is applicable to nano-fluid, the σ in above-mentioned formula
mconductivity for the nano-fluid of known quality mark; σ
1conductivity for base fluid; σ
2conductivity for nano particle; φ is the massfraction of nano particle.
(2) measure the conductivity of the nano-fluid of various known quality marks, according to formula (1), obtain the massfraction of nano-fluid and the relation between conductivity, matching obtains the relational expression between nano-fluid conductivity and massfraction;
(3) measure the conductivity of the nano-fluid of arbitrary moment suspension stability to be determined, the nano-fluid conductivity obtaining according to matching and the relational expression between massfraction, calculate the massfraction of the nano-fluid of suspension stability to be determined; According to gained massfraction, judge the stability of the nano-fluid of suspension stability to be determined.
Wherein, before the conductivity of the conductivity of measurement known quality mark nano-fluid and the nano-fluid of suspension stability to be determined, need elimination precipitation.Measuring process is carried out at 25 ℃ of constant room temperatures.
Embodiment:
1, measuring process is as follows:
(1) 2401-M conductance electrode 1, MP522 type Accurate pH/conductivity meter 2 and computing machine 3 are formed to experimental provision.Open pH/ conductivity meter preheating 30 minutes, according to the method for introduction of apparatus, first with standard solution, calibrate conductance electrode, then with washed with de-ionized water conductance electrode and after drying, start to measure.
(2) probe is put into the CuO/ deionized water nano-fluid suspending liquid just having prepared, rocked gently conductance electrode, itself and solution are fully contacted rear standing.
(3) by the time show reading out data after numerical stability, and temperature measured in record.
(4) each value is measured 5 times, and getting its mean value is experimental result, and the deviation between contrast each experiment value of discovery and mean value, in 3%, shows that the repeatability of experiment is better, and concrete data are as table 1.
Table 1 nano-fluid Experiment of Electrical Conductivity data
According to measured data, by linear fit, draw the regression equation between conductivityσ and massfraction φ:
σ＝1.36667+201.2φ （2）
2, judge the suspension stability of the nano-fluid of unknown massfraction
The conductivity of measuring the nano-fluid of unknown massfraction with said method is σ=8.73 μ S/cm, and by the relational expression that above-mentioned matching obtains, calculating its massfraction is φ=0.037%.Measure after 4 hours, the variation of its conductivity, data are as table 2.
Table 2 conductivity over time
| Time (h) | 1 | 2 | 3 | 4 |
| Conductivity (μ S/cm) | 8.65 | 8.14 | 7.88 | 7.72 |
| Reduce number percent | 0.92% | 6.76% | 9.74% | 11.57% |
From data above, along with the prolongation of time of repose, nano-fluid conductivity presents downtrending.From fitting formula, conductivity declines, and massfraction reduces, and the increase along with time of repose is described, nano-fluid has a certain amount of reunion precipitation.
The comparison of 3 the inventive method and settling methods
If Fig. 2 is the resulting result of settling methods.
In Fig. 2, in 5 color comparison tubes, be respectively just prepared, the sedimentation situation of nano-fluid after 1 hour, after 2 hours, after 3 hours and after 4 hours.As can be seen from the figure, along with the increase of time of repose, there is lamination in nano-fluid, and this is because nanoparticle agglomerates precipitation causes, and along with the increase of time, layering situation increases the weight of, and illustrates that precipitation capacity increases.
This phenomenon is consistent with the measured result of the invention described above method, and the reliability of method of the present invention has been described.And result of the present invention has been carried out quantitative test to this phenomenon, experimental result is more convincing.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (6)
1. a method of judging nano-fluid suspension stability, is characterized in that, comprises the steps:
(1) according to the relation between mass particle mark and conductivity in Maxwell's electromagnetic theory electrolyte suspending liquid, regard nano-fluid as potpourri that same electrolyte solution is the same, the base fluid of take in nano-fluid is conductor, the nano particle of take in described nano-fluid, as interspersing among the bead in conductor, is set up model; The Conductivity Calculation formula of known quality mark nano-fluid is:
In formula (1): σ
mconductivity for the nano-fluid of known quality mark; σ
1conductivity for base fluid; σ
2conductivity for nano particle; φ is the massfraction of nano particle;
(2) measure the conductivity of the nano-fluid of various known quality marks, according to formula (1), obtain the massfraction of nano-fluid and the relation between conductivity, matching obtains the relational expression between the massfraction of contained nano particle in nano-fluid conductivity and nano-fluid;
(3) measure the conductivity of the nano-fluid of arbitrary moment suspension stability to be determined, the nano-fluid conductivity obtaining according to matching and the relational expression between massfraction, calculate the massfraction of the nano-fluid of suspension stability to be determined; According to gained massfraction, judge the stability of the nano-fluid of suspension stability to be determined.
2. the method for judgement nano-fluid suspension stability according to claim 1, is characterized in that, the nano-fluid conductivity that matching obtains and the relational expression between massfraction are:
σ＝1.36667+201.2φ （2）
In formula (2): the conductivity that σ is nano-fluid; φ is the massfraction of nano particle.
3. the method for judgement nano-fluid suspension stability according to claim 1 and 2, is characterized in that, before the conductivity of the conductivity of measurement known quality mark nano-fluid and the nano-fluid of suspension stability to be determined, needs elimination precipitation.
4. the method for judgement nano-fluid suspension stability according to claim 3, is characterized in that, measuring process is carried out at 25 ℃ of constant room temperatures.
5. the method for judgement nano-fluid suspension stability according to claim 1, is characterized in that, the nano particle in the nano-fluid of known quality mark and the nano-fluid of suspension stability to be determined is spherical or class is spherical.
6. the method for judgement nano-fluid suspension stability according to claim 1, is characterized in that, it is characterized in that, measures conductivity and uses conductivity meter.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105510200A (en) * | 2015-11-23 | 2016-04-20 | 太原理工大学 | Nanoparticle suspension stability quantitative evaluation device |
| CN109042734A (en) * | 2018-07-26 | 2018-12-21 | 中国农业大学 | A kind of nano antibacterial agent for preventing and treating fungal diseases of plants |
| CN109883906A (en) * | 2019-02-21 | 2019-06-14 | 浙江大学 | A kind of nano metal two-phase fluid stability measurement method |
-
2013
- 2013-11-20 CN CN201310588963.3A patent/CN103712896A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| 王亚妹等: "纳米流体悬浮稳定性和电导率的关系研究", 《功能材料》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105510200A (en) * | 2015-11-23 | 2016-04-20 | 太原理工大学 | Nanoparticle suspension stability quantitative evaluation device |
| CN105510200B (en) * | 2015-11-23 | 2018-04-13 | 太原理工大学 | A kind of device of quantitative assessment nanoparticle suspension stability |
| CN109042734A (en) * | 2018-07-26 | 2018-12-21 | 中国农业大学 | A kind of nano antibacterial agent for preventing and treating fungal diseases of plants |
| CN109883906A (en) * | 2019-02-21 | 2019-06-14 | 浙江大学 | A kind of nano metal two-phase fluid stability measurement method |
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Application publication date: 20140409 |