HEAT TRANSFER OF NANOFLUIDS – BOOM OR BUST

Abstract

Significant controversy over reports of extraordinary heat transfer in nanofluids has existed. The results of work performed by our group to help resolve some of these issues will be discussed. Heat transfer in fluids is complex and includes phenomena such as conduction (thermal conductivity), convection (laminar and turbulent), and boiling. The results of tests performed with custom experimental apparatuses, including transient hot wire, pool boiling, quench, flow loops, and high-speed infrared (IR) thermography and digital imaging, will be discussed. Additionally, single phase pressure drop measurements for nanofluids will be presented. It will be shown that the effect of nanofluids on pressure drop and conductive and convective heat transfer can be explained by existing theories, if a nanofluids thermophysical properties are used. However, the enhancement of boiling heat transfer, particularly critical heat flux and quenching, is more challenging to interpret using existing theory because of surface effects. Accordingly, the insights gained from measurements of contact angle, IR imaging, and morphological data will be presented.