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Numerical study of instability of nanofluids: the coagulation effect and sedimentation effect.

Ni Y, Fan J, Hu Y - Nanoscale Res Lett (2011)

Bottom Line: Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids.The results indicate a superposition of coagulation and sedimentation effect of small nano-particles.Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, P, R, China. fanjr@zju.edu.cn.

ABSTRACT
This study is a numerical study on the coagulation as well as the sedimentation effect of nanofluids using the Brownian dynamics method. Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids. The rms fluctuation of the particle number concentration, as well as the flatness factor of it, is employed to study the formation and variation of the coagulation process. The results indicate a superposition of coagulation and sedimentation effect of small nano-particles. Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids. In addition, the effect of ζ potentials is against the formation of coagulation and positive to the stability of nanofluids.

No MeSH data available.


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The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 3).
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Figure 6: The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 3).

Mentions: This conclusion is also validated by the variations of R1 and R4 (Figure 6a, b, respectively). It is seen that the fluctuation of the number concentration of particles with ζ = 0.05 eV increases much more slowly than the cases with smaller ζ. Although the R1 and R4 for ζ = 0.05 eV are still increasing with time, which indicates that the coagulation process may still take place after a fairly long time, their effects against the formation of coagulation are very clear. In other words, it is positively beneficial for the stability of nanofluids.


Numerical study of instability of nanofluids: the coagulation effect and sedimentation effect.

Ni Y, Fan J, Hu Y - Nanoscale Res Lett (2011)

The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211237&req=5

Figure 6: The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 3).
Mentions: This conclusion is also validated by the variations of R1 and R4 (Figure 6a, b, respectively). It is seen that the fluctuation of the number concentration of particles with ζ = 0.05 eV increases much more slowly than the cases with smaller ζ. Although the R1 and R4 for ζ = 0.05 eV are still increasing with time, which indicates that the coagulation process may still take place after a fairly long time, their effects against the formation of coagulation are very clear. In other words, it is positively beneficial for the stability of nanofluids.

Bottom Line: Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids.The results indicate a superposition of coagulation and sedimentation effect of small nano-particles.Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, P, R, China. fanjr@zju.edu.cn.

ABSTRACT
This study is a numerical study on the coagulation as well as the sedimentation effect of nanofluids using the Brownian dynamics method. Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids. The rms fluctuation of the particle number concentration, as well as the flatness factor of it, is employed to study the formation and variation of the coagulation process. The results indicate a superposition of coagulation and sedimentation effect of small nano-particles. Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids. In addition, the effect of ζ potentials is against the formation of coagulation and positive to the stability of nanofluids.

No MeSH data available.


Related in: MedlinePlus