Nanofluids for Heat Transfer
Comparison of thermal conductivity enhancement in 4 vol % SiC nanofluids with EG/H2O and H2O as base fluids at various particle sizes.
Scanning electron micrograph image of a dried silicon-carbide nanofluid showing 100 nm size nanoparticles.
Argonne National Laboratory is developing water and ethylene glycol/water-based dispersions of nanoparticles for use as the heat transfer fluid (HTF) in liquid cooling systems. The addition of nanoparticles increases the thermal conductivity of liquids, enabling more efficient heat transfer in liquid cooling systems.Description
The heat transfer performance of any fluid results from the combination of thermo-physical properties such as thermal conductivity, viscosity, heat capacity and density. Introduction of nanoparticles to the base fluid affects all these properties. Heat capacity and density depend only on the concentration of the solid phase in the fluid and are unrelated to nanoparticle morphology (size, shape etc.). However, both thermal conductivity and viscosity are largely determined by the shape and size of the solid particles constituting the nanofluid systems.
By conducting a systematic study of two series of nanofluids with particles of average sizes ranging from 16 to 90 nm, we were able to suggest guidelines for engineering nanofluids and to indicate the conditions where nanoparticle suspensions becomes beneficial over base fluids.
It was shown that using larger particles provides lower viscosity and higher thermal conductivity increases that enhance heat transfer. On the other hand, the percent of viscosity increase due to introduction of nanoparticles is less if the viscosity of the base fluid is higher. The viscosity of nanofluids was shown to decrease faster with the temperature than that of the base fluids, while their thermal conductivity ratio of the nanofluid to base fluid is independent of temperature. Therefore the nanofluid’s heat transfer efficiency improves with increasing temperature.
In conclusion, we were able to show that nanoparticles allow solutions to behave more like pure liquids, limiting the changes that need to be made to existing liquid cooling systems so they can accept nanofluid HTFs. Note that optimal particle size (considering thermal conductivity, flow resistance, corrosiveness and erosiveness, stability, etc.) may not necessarily be nanoscale.Benefits
Nanoparticles added to liquids increase the liquids’ thermal conductivity, making for more efficient heat transfer.
Few changes need to be made to existing liquid cooling systems so they can accept nanoparticles (which are a very small size).Applications and Industries
- Closed-loop liquid cooling systems
- Chemical/rubber processing
- Petroleum refineries and power generation
- Electrical systems and power electronics
- Semiconductors and computing
- Production machinery and combustion engines
|Development Stage||Availability||Published||Last Updated|
|Proposed - This technology is still in the research stage.||Available - This technology is available for license. Please contact Argonne for licensing information.||04/05/2011||04/05/2011|