NANOTECHNOLOGY AND FLUID MECHANICS

MADE BY-

VEDANT PATEL (13BCH043)

YUGA CHITRAPU (13BCH062)

GUIDED BY-PROF. LEENA BORA

OVERVIEW

• How can Nanotechnology and Fluid Flow be related.

• Nanofluids and their applications.• Micropumps and Nanopumps.• Nanofluidics and its applications.• Nanofluidic Circuitry.

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.

Nanofluids• Nanofluids are dilute liquid

suspensions of nanoparticles with at least one of their principal dimensions smaller than 100 nm.

Deionized water prior to(left) and after (right)dispersion of Al2O3

nanoparticles

Oil prior to (left) andafter (right) evaporationof Cu nanoparticles

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

Preparation of Nanofluids

• Nanofluids are generally prepared using one of the following 2 methods :-

• One-Step Method.• Two-Step Method.

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.

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.

What happens due to Nanoparticles ?

Convective heat transfer coefficient

Thermal diffusivity

Viscosity

Thermal conductivity

Due to the Nanoparticles there is enhancement in :

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.

Enhancement in Thermal conductivity

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.

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.

Change in Viscosity

Enhancement of Heat Transfer coefficient

• The heat transfer coefficient of the nanofluid is higher than its base fluid.

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

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.

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.

Nuclear Reactors

• Possible applications include pressurized water reactor (PWR) primary coolant, standby safety systems, accelerator targets, plasma divertors, and so forth.

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.

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.

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.

Limitations of using Nanofluids

Poor long term stability of

suspension.

Lower specific heat .

High cost of

nanofluids.

Increased pressure drop and pumping

power.

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.

Micropumps

Applications

Aerospace and Aircraft. Automotive .

Biotechnology.

Chemical Processing.

Clinical and Analytical

Lab.Electronics. Energy/Fuel.

Environmental.

Food and Beverage.

General Industry.

Medical Equipment

and Devices.

Paints and Inks.

Pharmaceutical and

cosmetics.

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.

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),.

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.

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.

Fluidic Manipulation

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.

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.

Coulter Counter

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.

Lab On a Chip

Lab on a Chip

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.

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.

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.

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.

Nanofluidic logic devices

Diodes. Field-effect transistors.

Field-effect reconfigurable diode.

Ionic bipolar transistors.

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.

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.

References

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