This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or "nanofluids," was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band ͑Ϯ10% or less͒ about the sample average with only few outliers. The thermal conductivity of the nanofluids was found to increase with particle concentration and aspect ratio, as expected from classical theory. There are ͑small͒ systematic differences in the absolute values of the nanofluid thermal conductivity among the various experimental approaches; however, such differences tend to disappear when the data are normalized to the measured thermal conductivity of the basefluid. The effective medium theory developed for dispersed particles by Maxwell in 1881 and recently generalized by Nan et al. ͓J. Appl. Phys. 81, 6692 ͑1997͔͒, was found to be in good agreement with the experimental data, suggesting that no anomalous enhancement of thermal conductivity was achieved in the nanofluids tested in this exercise.
Dr. Gonzalez is Founder and President of LIMBS International (www.limbs.org), a 501(c)3 non-profit humanitarian organization that designs, creates and deploys prosthetic devices to transform the lives of amputees in the developing world by restoring their ability to walk. Since its founding in 2004, the LIMBS Knee has helped over one thousand amputees in almost 35 countries on four continents. Dr. Richard T. Schoephoerster, University of Texas, El PasoSince 2007 Dr. Schoephoerster has been the Dean of the College of Engineering at The University of Texas at El Paso where he leads a College of approximately 85 faculty members, 55 staff members, and 3500 students in 28 different BS, MS, and PhD degree programs. In the past seven years the total number of graduates per year has increased by 40%, and the number of annual doctoral graduates and annual research expenditures has almost quadrupled. During his tenure, UTEP has become one of the largest producers of Hispanic engineers at all levels (BS, MS, and PhD), and UTEP Engineering recently had the largest percentage of female engineering graduates at the doctoral level. For nine years running, UTEP has been listed in the top five engineering graduate schools for Hispanics by Hispanic Business Magazine. Prof. Jessica Townsend, Olin College of EngineeringJessica Townsend is a passionate proponent of undergraduate engineering curriculum innovation and is dedicated to finding pathways to innovation in traditional educational settings. She is an Associate Professor of Mechanical Engineering and the Associate Dean for Curriculum and Academic Programs at Olin College. Since joining the Olin College faculty in 2004, Dr. Townsend has worked as a facilitator and consultant with universities and professional organizations looking to improve engineering student engagement, and has contributed to the development of innovative pedagogies, courses, and curricula at Olin College, mainly in the design and mechanical engineering areas. Her technical area of interest is experimental thermal-fluids and she worked for many years on the development and characterization of nanofluids (colloidal suspensions of nanoparticles), mainly for thermal management applications. She now focuses on projects that effectively engage undergraduates in thermal-fluid and propulsion related areas, including recent work on a hybrid solid rocket test stand. Dr. Townsend has industry experience in both air-breathing propulsion, as a gas turbine performance engineer at Hamilton Sundstrand Power Systems, and in rocket propulsion, as a visiting engineer at Blue Origin, a commercial spaceflight company based in Seattle, WA.c American Society for Engineering Education, 2015 Page 26.635.1 Introducing Engineering Leadership: Lessons Learned from a Multi-Institutional Collaborative Process to Build a New Engineering Discipline from Scratch AbstractThe University of Texas at El Paso (UTEP), recognizing the growing emphasis on leadership development in engineering, has established a new engineering discipline calle...
In the search for new, more effective coolant fluids, nanoparticle suspensions have shown promise due to their enhanced thermal conductivity. However, there is a concomitant increase in the viscosity, requiring an increase in pumping power to achieve the same flow rate. Studies of flow cooling in simple geometries indicate that there is a benefit to using nanofluids, but it is difficult to justify extending these results to the far more complicated geometries. Moreover, with the variability of property measurements found in literature, it is possible to show conflicting results from the same set of flow-cooling data. In this work we present a self-contained study of the properties and effectiveness of an alumina in water nanofluid. Flow-cooling is studied in an off-the-shelf fluid cooling package for electronics to examine the effects of the particulates in a practical scenario. We measure the thermal conductivity and viscosity of the same suspensions to assure consistent interpretation of our results. We find that, while there is no anomalous enhancement of the thermal properties or transport, there is a benefit to using a low volume fraction alumina nanoparticle suspension over using the base fluid alone. In fact, there is an optimal volume fraction (1%) for this nanofluid and electronics cooling system combination that maximizes the heat dissipated. However, we find that this benefit decreases as the volume fraction, and hence the viscosity, increases. Understanding where the trade-off between viscosity increase and thermal conductivity increase occurs is critical to designing an electronics cooling system using a nanofluid as a coolant.
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