Material Properties and Characterization Prof. D. Poulikakos 2 nd Week On the Thermal Conductivity of Nanofluids
On the Thermal Conductivity of Nanofluids MWCNT in PAO Suggested Enhancement Mechanisms: Particle Brownian motion agitates the fluid, thus creating a micro-convection Clusters or agglomerates of particles and heat percolates preferentially along such clusters Choi S.U.S., et al. Appl. Phys. Lett., Vol. Basefluid molecules form a highlyordered high-thermal-conductivity layer around the particles 79, No. 14, 1 (2001) Monday, October 26, 2009 D-MAVT/IET/LTNT 2
Thermal Conductivity Measurements Transient Hot Wire Method Static Heated Plate Method Trans.1D axisymmetric heat conduction: Fourier s law: Monday, October 26, 2009 D-MAVT/IET/LTNT 3
On the Thermal Conductivity of Gold Colloids N. Shalkevich, W. Escher, T. Buergi, B. Michel L. Si-Ahmed and D. Poulikakos, On the Thermal Conductivity of Gold Nanoparticle Colloids, Langmuir, 2009. Monday, October 26, 2009 D-MAVT/IET/LTNT 4
On the Thermal Conductivity of Gold Colloids N. Shalkevich, W. Escher, T. Buergi, B. Michel L. Si-Ahmed and D. Poulikakos, On the Thermal Conductivity of Gold Nanoparticle Colloids, Langmuir, 2009. Monday, October 26, 2009 D-MAVT/IET/LTNT 5
Objectives: To compare nanofluid property measurements (particularly of thermal conductivity) performed with various experimental methods. To generate a reliable database of nanofluid properties (particularly thermal conductivity). Methodology: Blind identical samples sent to all participants. Participants adhere to same sample handling protocol Results collected, organized and reported by centralized administrators (MIT and IIT) Sample identity revealed a posteriori Monday, October 26, 2009 D-MAVT/IET/LTNT 6
List of organizations that submitted a letter of intent to participate in INPBE USA Argonne National Laboratory Illinois Institute of Technology Kent State University Massachusetts Institute of Technology METTS Corp. NIST Olin College of Engineering South Dakota School of Mines and Tech. Stanford University Texas A&M University Univ. of Missouri Univ. of Pittsburgh Univ. of Puerto Rico EUROPE CEA-Saclay ETH Zurich/ IBM Research Helmut-Schmidt University Armed Forces Queen Mary University of London / Silesian University of Technology Universite Libre de Bruxelles University of Leeds Universite' de Nantes Universita' di Napoli ASIA Chinese University of Hong Kong DSO National Laboratories Indian Institute of Technology, Kharagpur Indian Institute of Technology, Madras Indira Gandhi Centre for Atomic Research Korea University Korea Aerospace University Nanyang Technological University Tokyo Institute of Technology Monday, October 26, 2009 D-MAVT/IET/LTNT 7
Batch1: S1: Alumina nanorods in de-ionized water (1 vol.%) S2: Alumina nanoparticles (1 vol.%) in PAO + surfactant S3: Alumina nanoparticles (3 vol.%) in PAO + surfactant S4: Alumina nanorods (1 vol.%) in PAO + surfactant S5: Alumina nanorods (3 vol.%) in PAO + surfactant Handling Protocol: Do not sonicate or add surfactants Measure TC of each sample three times @ 25 C and optional @ 50 C Repeat measurements on a different day Monday, October 26, 2009 D-MAVT/IET/LTNT 8
Samples: S1: Alumina nanorods in de-ionized water (1 vol.%) S2: Alumina nanoparticles (1 vol.%) in PAO + surfactant S3: Alumina nanoparticles (3 vol.%) in PAO + surfactant S4: Alumina nanorods (1 vol.%) in PAO + surfactant S5: Alumina nanorods (3 vol.%) in PAO + surfactant Monday, October 26, 2009 D-MAVT/IET/LTNT 9
Sample Par*cle material Par*cle size, nm stabilizer Base fluid Par*cle concentra*on rela*ve thermal conduc*vity S1.1 alumina 80x10 nm rods S1.2 alumina 10 nm spheres S1.3 alumina 10 nm spheres S1.4 alumina 80x10 nm Rods S1.5 alumina 80x10 nm rods S2.1 gold 20 30 nm spheres S3.1 silica 22nm Spheres water 1 vol.% 1.047 PAO 1 vol.% 1.0528 PAO 3 vol.% 1.144 PAO 1 vol.% 1.065 PAO 3vol.% 1.213 trisodium citrate water 0.001 vol.% 0.999 water 31.1 vol.% 1.262 Monday, October 26, 2009 D-MAVT/IET/LTNT 10
Basic trends for thermal conductivity measurements: No nanofluid sample seems to have abnormally high thermal conductivity (defined as a very significant deviation from Maxwell s static model) Elongated particles (nanorods) yield higher thermal conductivity than spherical particles No substantive difference between results of different thermal measurement techniques Sample related issues are likely responsible for differing measurements in literature Basic trends for viscosity measurements: Viscosity data showed reasonably good agreement between different laboratories Nanofluid samples of spherical nanoparticles at low concentrations displayed Newtonian behavior while nanofluids with spherical nanoparticles at high concentrations or with rod-shaped particles showed non- Newtonian (shear thinning) behavior. Nanofluids displayed relative viscosities 10 times greater than predicted by dilute solution theories. General Conclusions: None of the fluids are probably suitable for use in electronics cooling Monday, October 26, 2009 D-MAVT/IET/LTNT 11