A nanofluid and a method for preparing the same

Abstract

The application relates to the technical field of heat exchange media, in particular to a nanofluid and a preparation method thereof. The preparation method comprises the following steps: configuring a composite solvent, adding a graphene composite into the composite solvent, uniformly dispersing, obtaining a graphene suspension, adding a surfactant into the graphene suspension, uniformly dispersing, and obtaining the nanofluid. The nanofluid is better stabilized and the heat conduction performance of the nanofluid is improved through the synergistic effect of the composite graphene, the composite solvent and the surfactant, so that the application requirement is better met. The nanofluid provided by the application has the advantages of high heat conduction coefficient, good stability, difficulty in freezing in winter and long-term use at a temperature of-50-100 DEG C through the synergistic effect of the specifically selected composite graphene, the composite solvent and the surfactant.

Description

TECHNICAL FIELD

[0001] The present application relates to heat exchange medium technical field, in particular to a kind of nanofluid and preparation method thereof. BACKGROUND

[0002] Heat transfer cooling process is needed in many industries such as microelectronics, transportation and manufacturing, but the traditional heat exchange medium has low thermal conductivity and poor heat transfer performance, which limits its application in thermal engineering.

[0003] Fluids with suspended nanoparticles, commonly known as nanofluids, are attracting global attention from a scientific and industrial perspective. For example, these nanofluids exhibit excellent thermal performance with higher thermal conductivity than traditional fluids; however, the stability of nanoparticles in the base fluid is poor, and they tend to settle, affecting the cooling effect of nanofluids. Moreover, in some regions, the temperature is relatively low in winter, and nanofluids are prone to freezing, affecting their use. SUMMARY

[0004] To solve the above problems, the present application provides a kind of nanofluid and preparation method thereof, the nanofluid provided by the present application not only has high thermal conductivity and good stability, but also is not easy to freeze in winter and can be used for a long time at-50~100 ℃.

[0005] The technical scheme adopted by the present application is:

[0006] A preparation method of nanofluid, comprising the following steps:

[0007] Prepare a composite solvent;

[0008] Add graphene composite to the composite solvent and disperse uniformly to obtain a graphene suspension;

[0009] Add a surfactant to the graphene suspension and disperse uniformly to obtain a nanofluid;

[0010] The composite solvent is a mixture of water and alcohol;

[0011] The graphene composite is a composite of graphene oxide with high oxidation degree and graphene with high reduction degree.

[0012] Further,

[0013] The total content of oxygen-containing groups in the graphene oxide is 30-60 wt%;

[0014] The content of the reduction graphene is 0.5-10 wt%.

[0015] Further, the mixing ratio of the graphene oxide with high oxidation degree and the graphene with high reduction degree in the graphene composite is 1:8-8:1.

[0016] Further, the alcohol in the composite solvent can be any of ethylene glycol, glycerol and isopropyl alcohol.

[0017] Further, the mixing ratio of water and alcohol in the composite solvent is 1:10-10:1.

[0018] Further, the surfactant is any of cetyltrimethylammonium bromide, dodecyl dimethyl benzyl ammonium chloride, sodium dodecyl sulfate, alkylphenol polyoxyethylene ether and sorbitan monooleate polyoxyethylene ether.

[0019] Further, the adding amount of the graphene composite in the graphene suspension is 0.05-2 mg / ml.

[0020] Further, the adding amount of the surfactant in the nanofluid is 0.05-2 mg / ml.

[0021] Further, the surfactant is added into the graphene suspension, and then ultrasonic dispersion is adopted to obtain the nanofluid.

[0022] The ultrasonic power is 1000-3000 W, and the ultrasonic dispersion time is 5-30 min.

[0023] Based on the same inventive concept, the application further provides a nanofluid prepared by the above preparation method.

[0024] The application has the following beneficial effects:

[0025] 1. The preparation method provided in this application, firstly, uses a mixture of water and alcohol solvents as a mixed solvent, which can obtain composite solvents with different polarities and fluidities. This not only meets the need for dispersion stability of different graphene composites, but also takes into account the need to protect the fluidity of the nanofluid. Secondly, it uses a composite of highly oxidized graphene oxide and highly reduced graphene. The highly reduced graphene can provide good thermal conductivity for the nanofluid, while the graphene oxide can be well dispersed in the solvent and assists in the stable dispersion of the highly reduced graphene in the solvent, slowing down sedimentation. By controlling the compounding ratio of highly oxidized graphene oxide and highly reduced graphene, a nanofluid with outstanding thermal conductivity and good stability can be obtained. Thirdly, the surfactant used in this application takes into account both the need for dispersion stability of graphene with different polarities and the need for heat and mass transfer of the nanofluid. In summary, the synergistic effect of the composite graphene, composite solvent, and surfactant used in this application better stabilizes the nanofluid and improves its thermal conductivity to better meet application requirements.

[0026] 2. The nanofluid provided in this application, through the synergistic effect of specially selected composite graphene, composite solvent and surfactant, not only has high thermal conductivity and good stability, but is also not easy to freeze in winter and can be used for a long time at a temperature of -50 to 100℃. Attached Figure Description

[0027] Figure 1 The images show the state of the nanofluids prepared in Examples 1-4 of this application after 7 days of storage (where a is Example 1; b is Example 2; c is Example 3; d is Example 4). Detailed Implementation

[0028] To facilitate understanding of the present invention, it will be described more fully below through embodiments, and preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Any other implementation schemes obtained by modifying or equivalently substituting the technical solutions of the present invention without inventive step are all within the protection scope of the present invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0030] The numerical values ​​disclosed in the embodiments of this invention are approximate values, not definitive values. Where error or experimental conditions permit, all values ​​within the error range may be included, and the specific numerical values ​​disclosed in the embodiments of this invention are not limited to those specified.

[0031] Unless otherwise specifically explained, various raw materials, reagents, instruments and equipment used in the present application can be purchased on the market or prepared by existing methods.

[0032] Example 1

[0033] The preparation method of the nanofluid provided in the present embodiment is as follows:

[0034] 60ml of ethylene glycol was added into 240ml of water under stirring, and mixed uniformly to obtain a composite solvent;

[0035] 0.1g of graphene oxide with an oxygen-containing group content of 22wt% and 0.2g of graphene with an oxygen-containing group content of 1.2wt% were added into the mixed solvent of water and ethylene glycol under stirring, and uniformly dispersed to obtain a graphene suspension;

[0036] 0.6g of cetyltrimethylammonium bromide was added into the graphene suspension under stirring, and ultrasonic dispersion was performed at a power of 2000W for 20 minutes to uniformly disperse the graphene, thereby obtaining a nanofluid.

[0037] Example 2

[0038] The preparation method of the nanofluid provided in the present embodiment is as follows:

[0039] 100ml of glycerol was added into 300ml of water under stirring, and mixed uniformly to obtain a composite solvent;

[0040] 0.2g of graphene oxide with an oxygen-containing group content of 22wt% and 0.25g of graphene with an oxygen-containing group content of 1.5wt% were added into the composite solvent of water and glycerol under stirring, and uniformly dispersed to obtain a graphene suspension;

[0041] 0.85g of sodium dodecyl sulfate was added into the graphene suspension under stirring, and ultrasonic dispersion was performed at a power of 2000W for 30 minutes to uniformly disperse the graphene, thereby obtaining a nanofluid.

[0042] Example 3

[0043] The preparation method of the nanofluid provided in the present embodiment is as follows:

[0044] 80ml of ethylene glycol was added into 320ml of water under stirring, and mixed uniformly to obtain a composite solvent;

[0045] 0.15g of graphene oxide with an oxygen-containing group content of 32wt% and 0.30g of graphene with an oxygen-containing group content of 0.8wt% were added into the composite solvent of water and glycerol under stirring, and uniformly dispersed to obtain a graphene suspension;

[0046] 0.9g of alkylphenol polyoxyethylene ether was added to the graphene suspension under stirring. The ultrasonic power was set to 2000W and the mixture was ultrasonically dispersed for 25 minutes until it was uniformly dispersed, thus obtaining nanofluid.

[0047] Example 4

[0048] The preparation method of nanofluid provided in this embodiment includes the following steps:

[0049] Add 100ml of ethylene glycol to 300ml of water while stirring, and mix well to obtain a composite solvent;

[0050] 0.2g of graphene oxide with an oxygen group content of 28wt% and 0.3g of graphene with an oxygen group content of 1.1wt% were added sequentially to a composite solvent of water and glycerol under stirring and dispersed evenly to obtain a graphene suspension.

[0051] 1.1g of dehydrated sorbitan monooleate polyoxyethylene ether was added to the graphene suspension under stirring. The ultrasonic power was set to 2000W and the mixture was ultrasonically dispersed for 20 minutes until it was uniformly dispersed, thus obtaining nanofluid.

[0052] See Figure 1 The image shown is a diagram of the state of the nanofluids prepared in Examples 1-4 after 7 days.

[0053] The nanofluids prepared in Examples 1-4 were subjected to comprehensive performance tests, and the results are shown in Table 1 and below:

[0054] Table 1 Comprehensive performance of nanofluids

[0055]

[0056] From Table 1 and Figure 1 It can be seen that the preparation method provided by the present invention produces nanofluids with anti-settling properties and good thermal conductivity. The nanofluids prepared by this method have high thermal conductivity and good stability, and play an excellent conductive role in the heat and mass transfer process.

[0057] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing nanofluids, characterized in that, Includes the following steps: Prepare composite solvents; The graphene composite was added to the composite solvent and dispersed evenly to obtain a graphene suspension. A surfactant was added to the graphene suspension and dispersed evenly to obtain a nanofluid. The composite solvent is a mixture of water and alcohol. The graphene composite is a composite of highly oxidized graphene oxide and highly reduced graphene. The total content of oxygen-containing groups in the graphene oxide is 30-60 wt%. The content of oxygen-containing groups in the reduced graphene is 0.5 to 10 wt%. The surfactant is any of the following: hexadecyltrimethylammonium bromide, dodecyldimethylbenzylammonium chloride, sodium dodecyl sulfate, alkylphenol polyoxyethylene ether, and sorbitan monooleate polyoxyethylene ether. The amount of surfactant added to the nanofluid is 0.05–2 mg / ml; The ratio of highly oxidized graphene oxide to highly reduced graphene in the graphene composite is 1:8 to 8:

1. The alcohol in the composite solvent can be any of ethylene glycol, glycerol, and isopropanol. The mixing ratio of water and alcohol in the composite solvent is 1:10 to 10:

1. The amount of surfactant added to the nanofluid is 0.05–2 mg / ml.

2. The method for preparing nanofluids according to claim 1, characterized in that, A surfactant was added to a graphene suspension, followed by ultrasonic dispersion to obtain a nanofluid. The ultrasonic power is 1000–3000W, and the ultrasonic dispersion time is 5–30 minutes.

3. A nanofluid prepared using the preparation method according to claim 1 or 2.

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