Keeping electronics cool
With copper oxide nanoparticles being the best, thermal resistance decreases as the volume fraction of nanoparticles is increased
Computer technology has transformed the way we live, but as consumers expect ever more from their devices at faster speeds, personal computers as well as larger computing systems can overheat. This can cause them to slow down, or worse, completely shut down.
Now researchers from Malaya and Brunei are reporting in the ACS journal Industrial & Engineering Chemistry Research that liquids containing nanoparticles could help devices stay cool and keep them running.
Rahman Saidur and colleagues point out that consumers demand a lot out of their gadgets. But that puts a huge strain on the tiny parts that whir away inside desktops and mainframe computers, which do the major data crunching.
The result is overheating.
Recent research has shown that substances called nanofluids have the potential to help keep electronics cool. They are made of metallic nanoparticles that have been added to a liquid, such as water. But there are many different kinds, and past research on their coolant abilities has been limited. To help sort through them, Saidur's team set out to determine which ones might work best.
Using something called a microchannel heat sink to simulate the warm environment of a working computer, they analysed three nanofluids for the traits that are important in an effective coolant.
These include how well they transfer heat, how much energy they lose, the friction they cause and their pumping power. All three performed better than water as coolants with the nanofluid mixture of copper oxide and water topping them all.
These different nanofluids consisted of water as a base fluid, with 0.4 to 2.0 volume percent of copper oxide (CuO), aluminium oxide (Al2O3), and titanium dioxide (TiO2) nanoparticles. The results generally showed that thermal resistance decreases as the volume fraction of nanoparticles is increased.
The CuO-water nanofluid was found to be the best coolant in terms of both minimising thermal resistance and maximising the pressure reduction. The energy efficiency of the heat sink increases as the volume fraction of nanoparticles increases. A maximum energy efficiency of 98.9 percent was obtained using the CuO-water nanofluid (at 2.0 vol percent).
The Al2O3-water and TiO2-water nanofluids (also at 2.0 vol percent) produced a maximum energy efficiency of 77.5 percent and 68.4 percent, respectively. The lowest exergy losses were: 19.2, 20.9, and 25.1 W for TiO2-water, Al2O3-water, and CuO-water nanofluids (all at 0.4 volume percent), respectively. The dimensionless friction factor was reduced as the nanoparticle volume concentration increased.
Also, the pumping power increased (to a high of 0.0173 W) as the mass flow rate increased.
The work is detailed in the paper, "Energy, Exergy, and Friction Factor Analysis of Nanofluid as a Coolant for Electronics," by S.S. Khaleduzzaman et al in Industrial & Engineering Chemical Research, 2014, 53 (25), pp 10512 - 10518. DOI: 10.1021/ie501242b
The authors acknowledge funding from the Ministry of Education Malaysia.
