Nanofluids are now developing technology in main purpose heat transfer stream. In paper has brief information on the introduction and preparation methods of nanofluids. This paper prepared from the study of online resources
2. Contents
• Introduction
• Preparation of Nano fluids
• Materials used for Nano particles and Base fluids
• Advanced flow and heat transfer challenges
• Concept of Nano fluids
• Thermal conductivity of Nano fluids
• Advantages
• Limitations
• Applications
• conclusion
3. Introduction
• Today’s toughest challenges facing by lot of industries, microelectronics,
automobiles, manufacturing process etc…are Thermal losses .
• Recent development of Nano technology brings out a new heat transfer
coolant called Nano fluids
• The term Nano fluids was first coined by CHOI where he describes hope of
Nano technology in future
• The term Nano fluids comes from Latin prefix Nano, it denotes 10−9
part of
it. Suspended Nano particles in various base fluids can alter fluid flow and
heat transfer characteristics of base fluids generally these are Nano fluids.
• Nano fluids owe its history to advanced fluids program at Argonne National
Laboratory(U.S)
4. Preparation of Nano fluids
• Nano particles are produced from several process such as direct evaporation,
gas condensation, chemical vapor condensation and chemical precipitation.
Out of these techniques, there are mainly two methods of Nano fluid
production:-
• Two step method
• Single step method
5. Two step method
• Two step method is most widely used for preparing Nano fluids
• Nano particles or Nano tubes are first produced as dry powder by
physical or chemical methods.Then Nano sized powder will be
dispersed in fluid with help of magnetic force , agitation, ultrasonic
agitation and ball milling. it is most economic method to produce
large scale Nano fluids due to high surface area and surface activity
Nano particles have tendency to aggregate.
• Surfactants are the substances used to enhance the stability of Nano
particles to fluid
6.
7. Single step method
• In single step method production and dispersion of Nano particles in
the base fluid. In this process uniformly dispersed particles are
suspended stably in the base fluid
• However there are some disadvantages, the most important one is
residual reactants in Nano fluids due to incomplete reaction or
stabilization is difficult to elucidate the Nano particle effect without
eliminating impurity effect
8.
9. Materials used for Nano particles and Base fluids
Nano particles materials include:
• Oxide ceramics- 𝐴𝑙2 𝑂3,CuO
• Metal carbides:-Sic
• Nitrides:-AlN, SiN
• Metals:-Al, Cu
• Non metals:-Graphite, Carbon Nano tubes
• Functionalized Nano particles
10. Base fluids include:
• Water
• Ethylene orTri ethylene glycol and other coolants
• Oils and lubricants
• Bio fluids
• Polymer solutions
• Other common fluids
11. Advanced flow and Heat transfer Challenge
• Heat rejection requirements are continually increases due to tends
towards faster speeds
• Cooling becomes one of top technical challenges facing high tech
industries such as micro electronics, automobile, transportation,
Manufacturing and Metrology
• Conventional method to increase heat flux rates :- extended surface
area such as fins and micro channels, flow rates in pumping power
• New technologies and new advanced fluids with potential to improve
flow and thermal characteristics
• Nanofluids are promising to meet and enhancing the challenges
12.
13. Concept of Nano fluids
• Conventional heat transfer fluids have poor thermal conductivity than
solids
• Conventional fluids that contain micro or Nano sized particles do not
work with emerging miniaturized technologies because they can clog
the passages of devices
• Modern Nano technology provide opportunity for producing Nano
particles
• Argonne national laboratory developed concept of Nano fluids
• Nano fluids are new class of advanced heat transfer fluids engineered
by emerging by Nano particles smaller than 100 Nano meter
14.
15. Thermal conductivity of Nano fluids
• The fluids which are using traditionally to heat transfer application
have rather low thermal conductivity by taking into account that raising
demands of production of Nano fluids.
The increase in thermal conductivity is predicted
• Brownian motion
• Interfacial layer
• Volume fraction of particles
16. Brownian Motion
• Brownian motion is the random motion of particles suspended in
a fluid (a liquid or a gas) resulting from their collision with the fast-
moving molecules in the fluid.
• This pattern of motion typically alternates random fluctuations in a
particle's position inside a fluid sub-domain with a relocation to
another sub-domain. Each relocation is followed by more fluctuations
within the new closed volume.This pattern describes a fluid
at thermal equilibrium, defined by a given temperature.
18. Interfacial Layer
• The region of space comprising and adjoining the phase boundary
within which the properties of matter are significantly different from
the values in the adjoining bulk phases, is called the surface layer or
interfacial layer.
19. Volume fraction of particles
• Nano fluids of highly conductive very low volume fractions
distributed in nano fluids may measurably increase the effective
thermal conductivity when compared to liquid
20. Advantages
• Due to Nano size particles, pressure drop is minimum.
• Higher thermal conductivity of nanoparticles will increase the heat transfer rate.
• Successful employment of nanofluid will lead to lighter and smaller heat exchanger.
• Heat transfer rate increases due to large surface area of the nanoparticles in the base fluid.
• Nanofluids are most suitable for rapid heating and cooling systems.
• Due to Nano size particles, fluid is considered as integral fluid.
• Good mixture nanofluids will give better heat transfer.
• Microchannel cooling without clogging. Nanofluids are not only a better medium for heat
transfer in general but they are also ideal for microchannel applications where high heat loads
are needed.
• Cost and energy saving. Successful employment of nanofluids will result in significant energy
and cost savings because heat exchange systems can be made smaller and lighter.
21. Limitations
• Nanofluids are useful in heating or cooling process for 24 - 36 hours
without any chemical treatment, as they are also not so stable.They
start settling down after 24 hours, which is the main disadvantage.
After treated the nanofluids chemically, they can be stable up to max.
72 hours, as per the literature, which is also not enough time to use
nanofluids in industries.
• Cost of Nano fluid production process is so expensive
22. Applications
• 1. Engine cooling
• 2. Nuclear cooling system
• 3. Cooling of electronic circuit
• 4. Refrigeration
• 5. Enhancement of heat transfer
exchange
• 6.Thermal storage
• 7. Biomedical application
• 8. Cooling of microchips
• 9. In defence and space application
• 10.Transportation
• 11. Petroleum industry
• 12. Inkjet printing
• 13. Environmental remediation
• 14. Surface coating
• 15. Fuel additives
• 16. Lubricant
23.
24. Conclusion
Nano fluid is trending and developing technology ,We expect Nano
fluids may be Next generation Heat transfer fluids,By the Nano
technology we can predict more advancement in nano fluids in 21st
centaury.
we are very glad to done this technology as Design and fabrication
project.
