nano fluids
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NANOTECHNOLOGY AND NANOMATERIALS
Author : Srinivas Dinakar.N , B.Pharmacy 3rd year.
Gokaraju Rangaraju College Of Pharmacy, kukatpally, Hyderabad.
• Nanotechnology refers to field of applied science whose theme is to control the matter on atomic and molecular scale.
•Nanotechnologically enhanced materials will enable a weight reduction accompanied by increase in stability and improved functionality.
INTRODUCTION
•NANOFLUID is a suspension of nanometer size particle in a base liquid.
•The particle here is defined as a small object that behaves as a whole unit in terms of its transport and properties.
•.In general carbon,metals,metal oxides serve as nano particles
•.Water ,ethylene,glycol,lubricants serve as base fluids in making nanofluids.
NANOFLUIDS
Nanofluids
They are effectively a bridge between bulk materials and atomic or molecular structures.
Size dependent properties are observed. eg:Quantum confinement is observed in semiconductors .
Increase in the energy that occurs when motion of the particle is restricted in one or more dimensions by the potential well. Superparamagnetism is seen in magnetic materials. Properties of particles in the fluids changes as their size approaches the nanoscale.
PROPERTIES
They exhibit special properties relative to the bulk material.
They exhibit high thermal conductivity which is given by the brownian motion of particles.
They exhibit unexpected visible properties because they are small enough to confine their electrons and produce quantum effect.
They have high surface to volume ratio.
They have property of sintering at lower temperatures.
The particles of the nanofluids ,at the small end size range are referred to as clusters. These are classified as: • HYBRID STRUCTURES: these are used in fluids which are used as materials in semiconductors and as dielectrics.
• QUANTUM DOTS: these are used in fluids which are used for quantization of electronic energy levels.
• LIPOSOME: these are used in fluids that find applications in clinical field as delivery systems for anticancer drugs and vaccines.
CLASSIFICATION
QUANTUM DOTS LIPOSOME
HYBRID STRUCTURES
Nanofluid characterization is necessary to establish an understanding and control of nanoparticle synthesis and applications. Characterization is done by using a variety of different techniques namely :
• Electron microscopy.• Dynamic light scattering.• Atom force microscopy.• X-Ray photoelectron microscopy.
CHARACTERIZATION
Study of nano particles by electron microscopy
Dynamic light scattering
Atom force microscopy
X-Ray Photoelectron microscopy
The common methods for creating nanoparticles which are the backbone of nanofluids are ATTRITION, PYROLYSIS.
• In ATTRITION macro or micro particles of the fluid are grounded in ball mill or other size reducing mechanism.
• In PYROLYSIS, a vapour precursor liquid or gas} is forced through an orifice at high pressure and burned. Resulting solid is air classified to recover oxide particles from by product gases
FABRICATION
ATTRITION
Pyrolysis
PYROLYSIS
THERMAL PLASMA can also deliver the energy necessary for the formation of nanoparticles such that nanofluid is produced.
Main types of thermo plasma are:
• DC PLASMA JET,
• DC ARC PLASMA,
• RADIO FREQUENCY INDUCTION PLASMA.
• In DC ARC PLASMA energy necessary for the evaporation and reaction is provided by the electric arc that forms between the anode and cathode.
• In RADIO FREQUENCY INDUCTION PLASMA the energy coupling to the plasma is accompanied through the electric field generated by the induction coil . Here the plasma is not in contact with electrodes.
• If the nanofluids having low melting point are to be produce then nanoparticles are made from INERT GAS AGGREGATION METHOD.
The metal chosen is vaporized in vacuum chamber and
super cooled with an inert gas stream. Super cooled metal vapour is then condensed into nanometer size particles. It is then mixed up with the base liquid and finally the desired
nano fluid mixture is obtained
INERT GAS AGGREGATION METHOD
1. Nano fluids are used to remove heat from the engine.
2. Used to reduce radiator size, pump size, temperature.
3. Used in heat transfer which depends on distribution volume fraction, thermal properties of suspended nanoparticles.
ADVANTAGES
4. Provide enhanced performance properties with respect to heat transfer.
5. Used in heat transfer applications in electronics, fuel cells. vehicle engines.
6. Yield numerous health and health care advances such as methods of delivering drugs, new cancer therapies, methods of early detection of diseases.
1.Nano particles present in the fluids can penetrate cells and tissues, move through the body and brain and cause biochemical damage.
2.They cause damage to the cardiovascular system.
SAFETY ISSUES
Use of nano fluids in a wide variety of applications appears promising but the development is hindered by factors like:
a. lack of agreement between results obtained in different laboratories.
b. poor characterization of suspensions.
c. size distribution of nanoparticles.
OUTLOOK AND CHALLENGES
Nanotechnology "the manufacturing technology of the 21st century," should let us economically build a broad range of complex molecular machines (including, not incidentally, molecular computers).
• It will let us build fleets of computer controlled molecular tools much smaller than a human cell and built with the accuracy and precision of the electronic chips.
• They could remove obstructions in the electronic circuits and can provide handful to the professionals.
> Nanotechnology is the upcoming branch of science where all of us can expect a new techno world.
Conclusion
REFERENCES
• Physics of micro and nano particles• Novel thermal properties of nanostructured
materials, Eastman, J.A. et al.; Materials Science Forum, Volume 312, 1999, Pages 629-634
• Mechanisms of heat flow in suspensions of nano-sized particles (nanofluids), P. Keblinski et al; International Journal of Heat and Mass Transfer, Volume 45, Issue 4, February 2002, Pages 855-863
