Third Day Poster Session, 17 June 2010 - NanoTR-VI

Poster Session, Thursday, June 17
Theme F686 - N1123
Design Of An Experimental Setup For Measuring Electrical Conductivity Of Nanofluids
Levent Cetin*, Alpaslan Turgut, I. H. Tavman
Dokuz Eylul University Mechanical Engineering Department, 35100 Bornova/zmir
Abstract- We represent a low cost instrumentation setup for measuring electrical conductivity of nanofluid. The
resulting setup is exploited to measure electrical conductivity of Alumina (Al 2 O 3 ) nanoparticles 25 nm diameter in
ethylene glycol for their different particle volume fractions. Approximately ten times increase in %5 particle volume
fraction is observed.
After the pioneering work of Choi[1] nanofluids
become a new class of heat transfer fluids. Their
potential benefits and applications in many
industries from electronics to transportation have
attracted great interest from many researchers both
experimentally and theoretically. Most of these
researches are related with the thermal conductivity
and viscosity of nanofluids. On the other hand,
electrical conductivity may give information on the
stability of the suspensions. However, there are few
studies concerning the electrical conductivity of
nanofluids[2].
Instrumentation apparatus consists of a signal
generator, two multimeters and a buffer circuit.
System is driven with sinusoidal output from signal
generator. Buffer circuit is exploited to isolate
conductivity measurement cell and low power
signal source. Buffer circuit is designed using OP07
opamp which has low offset value 75V [3].
Measurement probe is a four point type. The
configuration of the linear four-point probe is
shown in Figure. 1. Current is injected into a probe
on one end (probe a on figure) and extracted from
the probe on the other end (probe d on figure),
while the voltage difference between the two center
probes (b and c) is measured with a high input
impedance circuit. Current is measured from probe
d to ground terminal of the circuit.
d I
(3)
A V
The geometric parameters are unified by defining
electrode cell constant (d/A); where d is the length
of the column of liquid between the electrodes and
A is the area of the electrodes.
Table 1 Cell geometry
D [mm] A [mm 2 ] Cell coefficient [1 /mm]
1.85 1,65 1,119879
Conductivity of ethylene glycol is measured using
designed apparatus and using this reference value
we observe the linear increase on electrical
conductivity of Alumina (Al 2 O 3 ) nanoparticles 25
nm diameter in ethylene glycol for their different
particle volume fractions. Approximately ten times
increase in %5 particle volume fraction is observed.
Relative electrical conductivity
11
10 Al2O3-EG
9
8
7
6
5
4
3
2
1
0 1 2 3 4 5
Particle volume fraction (%)
Figure 2 Schematic representation of
instrumentation setup.
Figure 1 Schematic representation of
instrumentation setup.
The resistivity “” of the media is calculated using
Ohm’s law:
d V
R
(1)
A I
V A
(2)
I d
Following the fact, Electrical conductivity is the
reciprocal of electrical resistivity, it can be
formulated as:
In this study, an instrumentation setup using on
the shell electronics components and basic lab
equipment is designed. Using this system,
electrical conductivity of the Alumina (Al 2 O 3 )
nanoparticles in ethylene glycol is monitored.
Corresponding Author levent.cetin@deu.edu.tr
[1] Choi, S. U. S. 1995. Enhancing thermal conductivity
of fluids with nanoparticles. In Developments and
Applications of Non-Newtonian Flows. (FED 231), (99–
105). New York: American Society of Mechanical
Engineers.
[2] Ganguly S, Sikdar S, Basu, S 2009, Experimental
investigation of the effective electrical conductivity of
aluminum oxide nanofluids Powder Technology
Volume: 196 Issue: 3 Pages: 326-330 Published:
DEC 22 2009
[3] http://cds.linear.com/docs/Datasheet/OP07.pdf
6th Nanoscience and Nanotechnology Conference, zmir, 2010 671