Basic idea about Nanofluids ,what is nanofluid,why we are using,advantages and applications,synthesis.

1. NANOFLUIDS

2. • Introduction
• Conventional method of heat transfer
• Materials for nanoparticles and base fluids
• Preparation methods for nanofluid
• Thermal conductivity
• Comparision
• Advantages of nanofluids
• Disadvantages of nanofluids
• Application and Further research
CONTENTS

3. • Definition
• Dispersion of nanoparticles in various base fluids can alter the fluid flow
and heat transfer characteristics of the base fluids.These suspension of nano
sized particles in the base fluids are called nanofluids.
• Recent development of nanotechnology brings out a new heat transfer coolant
called ‘nanofluids’. These fluids exhibit larger thermal properties than
conventional coolants.
• The much larger relative surface area of nanoparticles,compared to those of
conventional particles, not only significantly improves heat transfer capabilities,
but also increases the stability of the suspension.

4. Concept of Nanofluids
• Conventional heat transfer fluids have inherently poor thermal
conductivity compared to solids
• Conventional fluids that contain mm or micro meter sized particles do not
work with the “miniaturized” technologies beacause they can clog the
tiny channels of these devices.
• Nanofluids are a new class of advanced heat transfer fluids engineered by
dispersing nanoparticles smaller than 100nm in diameter in conventional
heat transfer fluids.

5. Conventional Methods of Heat Transfer
Disperse micrometer
or millimeter sized
particles in heat
transfer fluids.
Major problem
• Settling down
• Cause wearing
• Large mass
J.A. Eastman,” Mechanisms of enhanced heat
transfer in nanofluids”

6. Nanoparticles and Base fluids
Nanoparticles
• Aluminum oxide (Al2O3)
• Titanium dioxide (TiO2)
• Copper oxide (CuO)
Base fluids
• Water
• Oil
• Ethylene glycol
• Refrigerants
U.S. Choi and J.A. Eastman, “Enhanced heat transfer
using nanofluids” U.S. Patent #6,221,275

7. Preparation Methods for Nanofluids
1. TWO-STEP METHOD
• Two-step method is the most widely used method for preparing
nanofluids
• Nanoparticles used in this method are first produced as dry
powders by chemical or physical methods. Then the nanosized
powder will be dispersed into a fluid in the second processing step
with the help of ultrasonic agitation, high-shera mixing, ball
milling and intensive magnetic force agitation.
• Two-step method is the most economic method to produce
nanofluids in large scale, beacause nanopowder synthesis
techniques have already been scaled up to industrial production
levels. Due to the high surface area and surface activity,
nanoparticles have the tendency to agglomerate.

9. • TWO-STEP METHOD

10. 2.SINGLE STEP METHOD
• To reduce the agglomeration of nanoparticles they developed a one-step
physical vapour condesnsation method to prepare nanofluids. The one-
step process consist of simultaneously making and dispersing the particles
in the fluid.
• In this method, the processes of drying, storage, transportation and
dispersion of nanoparticles are avoided, so the agglomeration of
nanoparticles is minimized, and the stability of fluids is increased. The
one-step processes prepare uniformly dispersed nanoparticles, and the
particles can be stably suspended in the base fluid.
• This method also have some disadvantages . Nanoparticles are not
properly cleaned.

11. SINGLE-STEP METHOD

12. THERMAL CONDUCTIVITY

13. comparision
parameter Conventional fluid Nanofluid
Thermal conductivity LOW HIGH
Heat capacity &
Heat transfer coefficient
LOW HIGH
Life of equipment HIGH LOW
Space required HIGH LOW
Overall cost HIGH LOW
Overall efficiency LOW HIGH

14. ADVANTAGES OF NANOFLUIDS
• Compared with suspended particles of millimeter-or-micrometer
dimensions which were used in base fluids to enhance heat transfer
of such fluids, nanofluids exhibit higher thermal conductivities.
• Many types of particles such as metallic and non-metallic, can be
added into fluids to form nanofluids.
• Suspended particles of the order of millimeters or even micrometers
may cause some severe problems such abrasive action of the
particles causes the clogging of flow channels, erosion of pipelines
etc which are not that severe in case of nanofluids.
• Micro and millimeter sized particles tend to settle rapidly. But
nanoparticles can remain suspended in base fluids for a longer time.
• The much larger relative surface area of nanoparticles compared to
those of conventional particles improves heat transfer capabilities

15. DISADVANTAGES
• Processing cost
• Agglomeration at higher pH value and also at high
temperatures because of the ability of the particle to overcome
thermal energy barrier leading to an increase in van der waals
forces and hence resulting in decrease of conductivity
• Maintain sufficient pressure and velocity of flow.

16. APPLICATION AND FURTHER
RESEARCH
• Cooling application
• Biomedical
• Defense
• Production of nanofluids
• Key energy transport mechanisms
• Thermal conductivity models
• Long term stability
• Green nanofluids

17. REFERENCES
• Sarit k. Das, Stephan U.S. Choi, Wenhua Yu,
T. Pradeep-2007, “NANOFLUIDS: SCIENCE
AND TECHNOLOGY”, A john Wiley & sons,
INC., Publication.

18. THANK YOU