Nanofluids
In recent years, fluids containing suspension of nanometer-sized particles (nanofluids) have been an active area of research due to their enhanced thermal properties over the base fluids. This makes them very attractive as heat transfer fluids in many applications. For example, nanofluids would be useful as coolants in the automobile and electronics industries. The increase in thermal conductivity of nanofluids has been attributed to a number of different phenomena including Brownian motion, clustering of nanoparticles, and liquid layering at the liquid/solid interface. Some of the articles discussing these issues in more detail are given below.1,2
Nanofluids Research
Figure 1: Click to enlarge
Figure 2: Click to enlarge
Existing theories cannot fully explain the observed increase in thermal conductivity. Therefore there is a need to come up with a better analytical model which captures the underlying physics accurately. We are working to develop a model to both better explain the increase and then possibly design fluids with enhanced thermal conductivity.
We are are also carrying out experimental studies on the thermal conductivity enhancement of water and ethylene glycol containing suspension of various nanoparticles, such as Al2O3, CuO, Au, Fe, and carbon nanonotubes. In addition, we study the role of surfactants in the absolute measurement of nanofluid thermal conductivity. A transient hotwire method is used to measure the thermal conductivity of fluids. Our experimental setup is shown in the figures below.
References
- "Mechanisms of heat flow in suspensions of nano-sized particles (nanofluids) ", P. Keblinski, S.R. Phillpot, S.U.S. Choi, J.A. Eastman, International Journal of Heat and Mass Transfer, vol 45, 2002, pp 855-863.
- "Thermal conductivity of nanoscale colloidal solutions (Nanofluids)", Ravi Prasher, Prajesh Bhattacharya, Patrick E. Phelan, Physics Review Letters, 94, 025901 (2005)