The temperature oscillation technique to measure the thermal diffusivity of a fluid consists of filling a cylindrical volume with the fluid, applying an oscillating temperature boundary condition at the two ends of the cylinder, measuring the amplitude and phase of the temperature oscillation at any point inside the cylinder, and finally calculating the fluid thermal diffusivity from the amplitude and phase values of the temperature oscillations at the ends and at the point inside the cylinder. Although this experimental technique was introduced by Santucci and co-workers nearly two decades ago, its application is still limited, perhaps because of the perceived difficulties in obtaining accurate results. Here, we attempt to clarify this approach by first estimating the maximum size of the liquid’s cylindrical volume, performing a systematic series of experiments to find the allowable amplitude and frequency of the imposed temperature oscillations, and then validating our experimental setup and the characterization method by measuring the thermal conductivity of pure water at different temperatures and comparing our results with previously published work.

%B International Journal of Heat and Mass Transfer %V 49 %P 2950-2956 %8 08/2006 %G eng %U http://www.sciencedirect.com/science/article/pii/S001793100600144X %N 17-18 %& 2950 %0 Journal Article %J International Journal of Heat and Mass Transfer %D 2006 %T Characterization of the Temperature Oscillation Technique to Measure the Thermal Conductivity of Fluids %A Prajesh Bhattacharya %A S. Nara %A P. Vijayan %A Tang, T. %A W. Lai %A Patrick E. Phelan %A Ravi S. Prasher %A David W. Song %A J. Wang %K Temperature oscillation technique %K Thermal conductivity %K thermal diffusivity %XThe temperature oscillation technique to measure the thermal diffusivity of a fluid consists of filling a cylindrical volume with the fluid, applying an oscillating temperature boundary condition at the two ends of the cylinder, measuring the amplitude and phase of the temperature oscillation at any point inside the cylinder, and finally calculating the fluid thermal diffusivity from the amplitude and phase values of the temperature oscillations at the ends and at the point inside the cylinder. Although this experimental technique was introduced by Santucci and co-workers nearly two decades ago, its application is still limited, perhaps because of the perceived difficulties in obtaining accurate results. Here, we attempt to clarify this approach by first estimating the maximum size of the liquid’s cylindrical volume, performing a systematic series of experiments to find the allowable amplitude and frequency of the imposed temperature oscillations, and then validating our experimental setup and the characterization method by measuring the thermal conductivity of pure water at different temperatures and comparing our results with previously published work.

%B International Journal of Heat and Mass Transfer %V 49 %P 2950-2956 %8 08/2006 %G eng %U http://www.sciencedirect.com/science/article/pii/S001793100600144X %N 17-18 %& 2950 %0 Journal Article %J Nanoletters %D 2006 %T Effect of Aggregation Kinetics on the Thermal Conductivity of Nanoscale Colloidal Solutions (Nanofluids) %A Ravi S. Prasher %A Prajesh Bhattacharya %A Patrick E. Phelan %B Nanoletters %V 6 %P 1529-1534 %G eng %& 1529 %0 Conference Paper %B International Mechanical Engineering Congress & Exposition %D 2006 %T Effect of Coloidal Chemistry on the Thermal Conductivity of Nanofluids %A Ravi S. Prasher %A Prajesh Bhattacharya %A Patrick E. Phelan %B International Mechanical Engineering Congress & Exposition %C Chicago, IL %8 11/2006 %G eng %0 Journal Article %J Nanoletters %D 2006 %T Enhanced Mass Transport in Nanofluids %A S. Krishnamurthy %A Prajesh Bhattacharya %A Patrick E. Phelan %A Ravi S. Prasher %XThermal conductivity enhancement in nanofluids, which are liquids containing suspended nanoparticles, has been attributed to localized convection arising from the nanoparticles' Brownian motion. Because convection and mass transfer are similar processes, the objective here is to visualize dye diffusion in nanofluids. It is observed that dye diffuses faster in nanofluids compared to that in water, with a peak enhancement at a nanoparticle volume fraction, *φ*, of 0.5%. A possible change in the slope of thermal conductivity enhancement at that same *φ* signifies that convection becomes less important at higher *φ*. The enhanced mass transfer in nanofluids can be utilized to improve diffusion in microfluidic devices.

The heat transfer abilities of fluids can be improved by adding small particles of sizes of the order of nanometers. Recently a lot of research has been done in evaluating the thermal conductivity of nanofluids using various nanoparticles. In our present work we address this issue by conducting a series of experiments to determine the effective thermal conductivity of alumina-nanofluids by varying the base fluid with water and antifreeze liquids like ethylene glycol and propylene glycol. Temperature oscillation method is used to find the thermal conductivity of the nanofluid. The results show the thermal conductivity enhancement of nanofluids depends on viscosity of the base fluid. Finally the results are validated with a recently proposed theoretical model.

%B ASME International Mechanical Engineering Congress and Exposition, November 5-11, 2005 %I ASME %C Orlando, FL %8 11/2005 %@ 0-7918-4221-5 %G eng %R 10.1115/IMECE2005-81494 %0 Journal Article %J Physical Review Letters %D 2005 %T Thermal Conductivity of Nanoscale Colloidal Solutions (Nanofluids) %A Ravi S. Prasher %A Prajesh Bhattacharya %A Patrick E. Phelan %B Physical Review Letters %V 94 %G eng %N 025901-1 – 025901-4. %& 025901-1 %0 Journal Article %J Journal of Applied Physics %D 2004 %T Brownian Dynamics Simulation to Determine the Effective Thermal Conductivity of Nanofluids %A Prajesh Bhattacharya %A Saha, S.K. %A Ajay K. Yadav %A Patrick E. Phelan %A Ravi S. Prasher %K complex fluids %K Disperse systems %K Thermal conduction in nonmetallic liquids %XA nanofluid is a fluid containing suspended solid particles, with sizes on the order of nanometers. Normally, nanofluids have higher thermal conductivities than their base fluids. Therefore, it is of interest to predict the effective thermal conductivity of such a nanofluid under different conditions, especially since only limited experimental data are available. We have developed a technique to compute the effective thermal conductivity of a nanofluid using Brownian dynamics simulation, which has the advantage of being computationally less expensive than molecular dynamics, and have coupled that with the equilibrium Green-Kubo method. By comparing the results of our calculation with the available experimental data, we show that our technique predicts the thermal conductivity of nanofluids to a good level of accuracy.

%B Journal of Applied Physics %V 95 %P 6492–6494 %8 06/2004 %G eng %N 11 %& 6492 %R 10.1063/1.1736319 %0 Conference Paper %B 1st International Symposium on Micro & Nano Technology %D 2004 %T Determining the Effective Viscosity of a Nanofluid Using Brownian Dynamics Simulation %A Prajesh Bhattacharya %A Patrick E. Phelan %A Ravi S. Prasher %B 1st International Symposium on Micro & Nano Technology %C Honolulu, HI %8 03/2004 %G eng %0 Conference Paper %B International Mechanical Engineering Congress & Exposition, %D 2004 %T Evaluation of the Temperature Oscillation Technique to Calculate Thermal Conductivity of Water and Systematic Measurement of the Thermal Conductivity of Aluminum Oxide – Water Nanofluiids %A Prajesh Bhattacharya %A P. Vijayan %A Tang, T. %A S. Nara %A Patrick E. Phelan %A Ravi S. Prasher %A J. Wang %A David W. Song %B International Mechanical Engineering Congress & Exposition, %C Anaheim, CA %8 11/2004 %G eng %0 Conference Proceedings %B Pulmonary Research Forum: American Lung Association of Arizona & New Mexico %D 2004 %T Numerical Tools For Particle- Fluid Interactions %A R. Calhoun %A Patrick E. Phelan %A Ajay K. Yadav %A Prajesh Bhattacharya %B Pulmonary Research Forum: American Lung Association of Arizona & New Mexico %8 02/2004 %G eng %0 Conference Paper %B National Heat Transfer Conference %D 2003 %T Determining the Effective Thermal Conductivity of a Nanofluid Using Brownian Dynamics Simulation %A Prajesh Bhattacharya %A Saha, S.K. %A Ajay K. Yadav %A Patrick E. Phelan %A Ravi S. Prasher %B National Heat Transfer Conference %C Las Vegas, NV %8 07/2003 %G eng %0 Conference Proceedings %B BioDevice Interface Science and Technology Workshop %D 2002 %T Modeling the Behavior of F1-ATPase Biomolecular Motors Using Brownian Dynamics Simulation %A Prajesh Bhattacharya %A Patrick E. Phelan %B BioDevice Interface Science and Technology Workshop %C Scottsdale, AZ %8 09/2002 %G eng %0 Conference Paper %B US-Japan Nanotherm Seminar: Nanoscale Thermal Science and Engineering %D 2002 %T Understanding the Behavior of an F1-ATPase Biomolecular Motor Using Brownian Dynamics Simulation %A Prajesh Bhattacharya %A Patrick E. Phelan %B US-Japan Nanotherm Seminar: Nanoscale Thermal Science and Engineering %C Berkeley, CA %8 06/2002 %G eng %0 Journal Article %J Annual Review of Heat Transfer %D 1995 %T Nanofluids for Heat Transfer Applications %A Patrick E. Phelan %A Ravi S. Prasher %A Prajesh Bhattacharya %B Annual Review of Heat Transfer %V 14 %P 255-275 %G eng %& 255