1.5 ASSUMPTIONS
It is important to assume that some of the nano particles will deposit on
the copper tubing and will not deposit on the rubber tubing. It is important to assume the nano particles
will not deposit on the rubber tubing.
It is also important to assume that there will be no heat loss as the
nano fluid travels from the tank through the rubber tubing.
Experiments will be conducted using the same procedures and equipment and
will have the same factors monitored.
Temperature and flow rates were measured at steady state indicated by the temperatures steady for a
ten minute period.
1.6 NANO FLUIDS
Nano fluids, the fluid suspensions of nonmaterial’s, have
shown many interesting properties, and the distinctive features offer
unprecedented potential for many applications. The recent progress on the study
of nano fluids, such as the preparation methods, the evaluation methods for the
stability of nano fluids, and the ways to enhance the stability for nano
fluids, the stability mechanisms of nano fluids, and presents the broad range
of current and future applications in various fields including energy and
mechanical and biomedical fields. At last, the paper identifies the opportunities
for future research.
Nano fluids are a new class of fluids engineered by
dispersing nanometer-sized materials (nano particles, nano fibers, nano tubes,
nano wires, nano rods, nano sheet, or droplets) in base fluids. In other words,
nanofluids are nanoscale colloidal suspensions containing condensed nano
materials. They are two-phase systems with one phase (solid phase) in another
(liquid phase). Nano fluids have been found to possess enhanced thermo physical
properties such as thermal conductivity, thermal diffusivity, viscosity, and
convective heat transfer coefficients compared to those of base fluids like oil
or water. It has demonstrated great potential applications in many fields.
For a two-phase system, there are some important issues we
have to face. One of the most important issues is the stability of nano fluids,
and it remains a big challenge to achieve desired stability of nano fluids. In
this paper, we will review the new progress in the methods for preparing stable
nano fluids and summarize the stability mechanisms.
In recent years, nano
fluids have attracted more and more attention. The main driving force for nano
fluids research lies in a wide range of applications. Although some review
articles involving the progress of nano fluid investigation were published in
the past several years , most of the reviews are concerned of the experimental
and theoretical studies of the thermo physical properties or the convective
heat transfer of nano fluids. The purpose of this paper will focuses on the new
preparation methods and stability mechanisms, especially the new application
trends for nano fluids in addition to the heat transfer properties of nano
fluids. We will try to find some challenging issues that need to be solved for
future research based on the review on these aspects of nano fluids.