Nano fluids

1. DEPARTMENT OF MECHANICAL ENGINEERING
TECHNICAL SEMINAR
ON
NANOFLUIDS
Presented by
B.SRI SAI FANINDRA
19281A0304
ME

2. Nano fluids are the new class engineered fluid with high thermal
conductivity obtained by suspending nanometer size (1-100nm)
particles in a base fluid like water ,ethylene glycol, oil etc.
NANOFLUIDS

4. NANOPARTICLES AND BASE FLUIDS
Nanoparticles
•Aluminum oxide (Al2O3)
• Titanium dioxide (TiO2)
•Copper oxide (CuO)
Base fluids
•Water
•Oil
•Ethylene glycol

5. Use of Nanoparticles
Studies of thermal conductivity of suspensions have been confined to
mm- or μm-sized particles.
The major challenge is the rapid settling of these particles in fluids.
Nanoparticles stay suspended much longer than micro-particles and, if
below a threshold level and or enhanced with surfactants/stabilizers, remain
in suspension almost indefinitely.
Furthermore, the surface area per unit volume of nanoparticles is much
larger (million times) than that of microparticles (the number of surface
atoms per unit of interior atoms of nanoparticles, is very large).
These properties can be utilized to develop stable suspensions with
enhanced flow, heat-transfer, and other characteristics.

6. Methods for Producing Nanoparticles/Nanofluids
Two nanofluid production methods has been developed in ANL to allow
selection of the most appropriate nanoparticle material for a particular
application.
In two-step process for oxide nanoparticles (“Kool-Aid” method),
nanoparticles are produced by evaporation and inert-gas condensation
processing, and then dispersed (mixed, including mechanical agitation and
sonification) in base fluid.
In one-step process simultaneously makes and disperses nanoparticles
directly into base fluid; best for metallic nanofluids.

7. 1.Two step method

8. 2.One step method

9. Figure 1: ZrO2 in water that
produced
with Two Step method
Figure 2: Cu nanoparticles in ethylene
glycol produced with One Step
method

10. Stability of Nanofluid
The agglomeration of nanoparticles results in not only the
settlement and clogging of microchannels but also the decreasing
of thermal conductivity of nanofluid. So stability evaluation
methods for nanofluid are-:
Sedimentation and Centrifugation
Zeta potential analysis
Spectral absorbency analysis

11. Ways to Enhance the Stability of Nanofluid
1) Use of various surfactants in Nanofluid
• Non ionic surfactant without charge groups in its head
• Anionic surfactant with negatively charged groups
• Cationic surfactant with positively charged groups
• Amphoteric surfactant with zwitterionic head groups
2) Surface Modification techniques
3) By dominating the repulsive force between the particles

12. Stability Mechanism of Nanofluid

13. Thermal Conductivity
According to the report of Argonne National Laboratory, eight
parameters effect the thermal conductivity of nanofluids, they got
these results from about 124 researchers experiments, these effects
are:
1.Particle volume concentration
2.Particle materials
3.Particle size
4.Particle shape
5.Base fluid material
6.Temperature
7.Additive
8.Acidity

15. Experimental Studies on Thermal Conductivity of Nanofluids
Investigator Particles Size (nm) Fluids Observations
Eastman et al (1997) Al2O3/CuO/Cu 33/36 water,oil 60% improvement
for 5 vol%
CuO particles in
water.
Lee et al (1999) Al2O3/CuO 24.4,38.4/18.6,23.6 water,EG 20% improvement for 4
vol%
Cuo/EG mixture.
Das et al (2003) Al2O3/CuO 38.4/28.6 water 2-4 fold increase
over range of
21oC to 52oC.
Hong et al (2005) Fe 10 EG 18% increase for
0.55 vol% Fe/EG
nanofluids.
Li and Peterson
(2006)
Al2O3/CuO 36/29 water enhancement with
volume fraction
and temperature
Liu et al (2005) CNTs Ø20-30 μm EG,EO 12.4% for EG at 1
vol%, 30% for
EO at 2 vol%.

16. ADVANTAGES OF NANOFLUIDS
 High specific surface area and therefore more heat transfer
surface between particles and fluids.
 High dispersion stability with predominant Brownian motion
of particles.
 Reduced pumping power
 Reduced particle clogging
 Adjustable properties, including thermal conductivity and
surface wet ability, by varying particle concentrations to suit
different applications.

17. DISADVANTAGES
• High Processing cost
• High viscosity
• Lower specific heat
• Long term fluid settling
• In ability to sustain flow boiling

18. Applications of Nanofluids
Heat transfer Intensification
Electronic Application
Transportation
Industrial Cooling Application
Heating Building
 Reducing Pollution
Nuclear System Cooling
Space and Defense
Mechanical Application
Biomedical Application

19. Conclusion
 Studies of nanofluids reveals high thermal
conductivities and heat transfer coefficients compared
to those of conventional fluids.
 These characteristic features of nanofluids make them
suitable for the next generation of flow and heat-
transfer fluids.
 Pioneering nanofluids research has inspired physicists,
chemists, and engineers around the world.

20. THANK YOU…