This document discusses nanotechnology and its relation to fluid mechanics. It begins by outlining how nanotechnology can be applied to fluid flow and properties. It then discusses nanofluids, how they are made, and their enhanced thermal conductivity and applications in areas like industrial cooling, smart fluids, nuclear reactors, and fuel. It also discusses micropumps and their applications. Next it covers nanofluidics, properties in nanofluidics, and applications like lab-on-a-chip devices and coulter counting. Finally it discusses nanofluidic circuitry, basic principles, logic devices, fabrication, and applications.
2. OVERVIEW
• How can Nanotechnology and Fluid
Flow be related.
• Nanofluids and their applications.
• Micropumps and Nanopumps.
• Nanofluidics and its applications.
• Nanofluidic Circuitry.
3. Nanotech and Fluid Flow
• Nanotechnology is the study and application of
the process at a Nano level (<10-9 meter).
• At the Nano level the properties of the fluid
completely change and some of the properties
are even enhanced to a significantly large level.
• Thus the Nanotech can be applied to the fluid
and its flow and some new technologies can be
developed like the super-hydrophobic coating,
some super fluids like magnetic fluids and even
nanopumps can developed.
4. Nanofluids
• Nanofluids are dilute liquid
suspensions of nanoparticles with at
least one of their principal dimensions
smaller than 100 nm.
Deionizedwaterpriorto Oil priorto (left)and
5. Materials for nanoparticles and
base fluids.
1. Nanoparticle materials include:
• Oxide ceramics – Al2O3, CuO
• Metal carbides – SiC
• Nitrides – AlN, SiN
• Metals – Al, Cu
• Nonmetals – Graphite, carbon nanotubes
• Layered – Al + Al2O3, Cu + C
• PCM – S/S
• Functionalized nanoparticles
2. Base fluids include:
• Water
• Ethylene- or tri-ethylene-glycols and other coolants
• Oil and other lubricants
• Bio-fluids
• Polymer solutions
• Other common fluids
6. Preparation of Nanofluids
• Nanofluids are generally prepared using
one of the following 2 methods :-
• One-Step Method.
• Two-Step Method.
7. One step method
• The one-step process consists of
simultaneously making and dispersing the
particles in the fluid.
• The vacuum-SANSS (submerged arc
nanoparticle synthesis system) is an efficient
method to prepare nanofluids using different
dielectric liquids.
• One-step physical method cannot synthesize
nanofluids in large scale, and the cost is also
high, so the one-step chemical method is
developing rapidly.
8. Two step method
• In this method nanoparticles, nanofibers,
nanotubes, or other nanomaterials used 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 intensive magnetic force agitation,
ultrasonic agitation, high-shear mixing,
homogenizing, and ball milling.
• Two-step method is the most economic method
to produce nanofluids in large scale.
9. What happens due to
Nanoparticles ?
Due to the Nanoparticles there is enhancement in :
10. Thermal conductivity
• Nanofluids exhibit enhanced thermal conductivity,
which goes up with increasing volumetric fraction
of nanoparticles.
• The effects of several important factors such as
particle size and shapes, clustering of particles,
temperature of the fluid, and dissociation of
surfactant can be seen on the thermal conductivity
of nanofluids.
• It is important to do more research so as to
ascertain the effects of these factors on the
thermal conductivity of wide range of nanofluids.
12. Enhancement in Thermal
diffusivity
• Thermal diffusivity is the thermal conductivity divided by
density and specific heat capacity at constant pressure.
It measures the ability of a material to conduct thermal
energy relative to its ability to store thermal energy. It
has the SI unit of m²/s. Thermal diffusivity is usually
denoted α . The formula is:
• As it is directly propotional to K, it also increases with the
increase in the nanoparticles suspended.
13. Change in Viscosity
• In a Nanofluid as the volume fraction of
the nanoparticles increase the viscosity
increases. When the temperature
increases the viscosity decreases but then
also it is more than the base fluid.
15. Enhancement of Heat
Transfer coefficient
• The heat transfer coefficient of the
nanofluid is higher than its base fluid.
16. Applications of Nanofluids
Industrial Cooling Smart Fluids Nuclear Reactors
Nanofluid Drug
Delivery
Automotive
Applications
Nanofluid Coolant Nanofluid in Fuel
Cooling of
Microchips
Micro scale
Fluidic
Applications
Extraction of
Geothermal
Power and Other
Energy Sources
Cryopreservation
and
Nanocryosurgery
Sensing and
Imaging
17. Industrial Cooling
• As the thermal conductivity as well as the heat
transfer coefficient is higher in the nanofluids
than the base fluid it has great application in
the industrial cooling process.
18. Smart fluids
• In a recent paper published in the March 2009 issue of
Physical Review Letters, Donzelli showed that a particular
class of nanofluids can be used as a smart material working
as a heat valve to control the flow of heat. The nanofluid can
be readily configured either in a “low” state, where it conducts
heat poorly, or in a “high” state, where the dissipation is more
efficient.
19. Nuclear Reactors
• Possible applications include pressurized
water reactor (PWR) primary coolant,
standby safety systems, accelerator
targets, plasma divertors, and so forth.
20. Nanofluid in Fuel
• It was shown that the combustion of diesel fuel
mixed with aqueous aluminum nanofluid
increased the total combustion heat while
decreasing the concentration of smoke and
nitrous oxide in the exhaust emission from the
diesel engine.
21. Cooling of Microchips
• A principal limitation on developing smaller
microchips is the rapid heat dissipation.
However, nanofluids can be used for liquid
cooling of computer processors due to
their high thermal conductivity.
22. Nanofluid in Drug Delivery
• As nanofluids are suspension of nanoparticles
in a solvent, nanoparticles of the drug
corresponding to the disease like Cancer can
be suspended in a liquid and can be given to
the body to reach the affetced area.
• As the particles are in the nanometer range
their delivery becomes easy and also more
affective.
23. Limitations of using
Nanofluids
Poor long term
stability of
suspension.
Lower specific
heat .
High cost of
nanofluids.
Increased
pressure drop
and pumping
power.
Not enough
developments.
24. Micropumps
• Although any kind of small pump is often referred to as
micropump, a more accurate and up-to-date definition restricts
this term to pumps with functional dimensions in the micrometer
range. Such pumps are of special interest in microfluidic
research, and have become available for industrial product
integration in recent years. Their miniaturized overall size,
potential cost and improved dosing accuracy compared to
existing miniature pumps fuel the growing interest for this
innovative kind of pump.
29. Nanofluidics
• Nanofluidics is the study of the behavior,
manipulation, and control of fluids that are
confined to structures of nanometer (typically
1-100 nm) characteristic dimensions (1 nm =
10−9 m).
• Fluids confined in these structures exhibit
physical behaviors not observed in larger
structures, such as those of micrometer
dimensions and above, because the
characteristic physical scaling lengths of the
fluid, (e.g. Debye length, hydrodynamic
radius) very closely coincide with the
dimensions of the nanostructure itself.
30. Properties in Nanofluidics
• The physical constraints induce regions of the
fluid to exhibit new properties not observed in
bulk, e.g. vastly increased viscosity near the
pore wall; they may effect changes in
thermodynamic properties and may also alter
the chemical reactivity of species at the fluid-
solid interface.
• A particularly relevant and useful example is
displayed by electrolyte solutions confined in
nanopores that contain surface charges, i.e. at
electrified interfaces. Eg. Nanocapillary Array
Membrane (NCAM),.
31. Nanocapillary Array
Membrane (NCAM)
• The NCAM is composed of a large number
of parallel nanocapillaries, each of which
have a pore radius, a/2, which is
approximately the same size as the Debye
length.
32. Use of NCAMs
• The drastically enhanced surface-to-volume ratio
of the pore results in the presence of more number
of ions charged oppositely to the static wall
charges over co-ions (possessing the same sign
as the wall charges).
• In many cases the near-complete exclusion of co-
ions takes place, such that only one ionic species
exists in the pore.
• This can be used for manipulation of species with
selective polarity along the pore length to achieve
unusual fluidic manipulation schemes not possible
in micrometer and larger structures.
34. Applications of Nanofluidics
Coulter counting.
Analytical
separations.
Determinations of
Biomolecules.
Handling of mass-
limited samples.
MicroTotal
Analytical Systems
or Lab-on-a-chip
structures.(eg.
NCAM).
Nano-optics for
producing tuneable
microlens array.
Biotechnology,
medicine and
clinical diagnostics.
35. Coulter counting
• A Coulter counter is an apparatus for counting and
sizing particles suspended in electrolytes. It is
used for cells, bacteria, prokaryotic cells and virus
particles.
• A typical Coulter counter has one or more
microchannels that separate two chambers
containing electrolyte solutions.
• As fluid containing particles or cells is drawn
through each microchannel, each particle causes a
brief change to the electrical resistance of the
liquid. The counter detects these changes in
electrical resistance.
37. Lab on a Chip
• A lab-on-a-chip (LOC) is a device that
integrates one or several laboratory
functions on a single chip of only millimeters
to a few square centimeters in size.
• LOCs deal with the handling of extremely
small fluid volumes down to less than pico
liters.
40. Pros and Cons of LOCs
PROS.
Low fluid volumes
consumption.
Faster analysis
and response
times.
Better process
control.
Compactness of
the systems.
Massive
parallelization.
Lower fabrication
costs.
CONS.
Not yet fully developed.
Physical and chemical
effects.
Detection principles may
not always scale down in a
positive way.
Rather poor in a relative
way compared to precision
engineering.
41. Challenges
• There are a variety of challenges associated
with the flow of liquids through carbon
nanotubes and nanopipes.
• A common occurrence is channel blocking due
to large macromolecules in the liquid.
• Also, any insoluble debris in the liquid can
easily clog the tube.
• A solution for this researchers are hoping to find
is a low friction coating or channel materials
that help reduce the blocking of the tubes.
42. Nanofluidic Circuitry
• Nanofluidic circuitry is a nanotechnology aiming
for control of fluids in nanometer scale.
• Due to the effect of an electrical double layer
within the fluid channel, the behavior of
nanofluid is observed to be significantly
different compared with its microfluidic
counterparts.
• Phenomenon of fluids in nano-scale structure
are discovered to be of different properties in
electrochemistry and fluid dynamics.
43. Basic Principles
• Electrolytes are basically charged
solutions so when they pass through the
channels the surface charge on the
channel attract counter ions and repel co-
ions. This leads the formation of electric
double layer.
• In Nanochannels since the length is in the
order of Debye Length it is possible to
manipulate the flow electrolyte.
45. Fabrication
• The advantage of nanofluidic devices is from its
feasibility to be integrated with electronic circuitry.
Because they are built using the same
manufacturing technology, it is possible to make a
nanofluidic system with digital integrated circuit on
a single chip. Therefore, the control and
manipulation of particles in the electrolyte can be
achieved in a real-time.
46. Applications
Chemistry, molecular biology and medicine.
Nanoparticles for drug delivery, gene therapy and nanoparticle
toxicology on a micro-total-analysis system.
Analytical chemistry and biochemistry, liquid transport and
metering, and energy conversion.
Sorting and separation for short strand DNA.
Chromatography.
Energy conversion.
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