Biomedical Engineering Reference
In-Depth Information
to conventional coolants which are expected to improve the boiling heat
transfer in devices.
10.4.2 Coolants in manufacturing processes
Most traditional and advanced manufacturing processes require a coolant
to absorb the high amount of heat generated during manufacturing
operations. Conventional coolants have poor heat absorbing quality, thus
increasing the amount of coolant that needs to be circulated. This increased
amount of coolant circulating at a higher rate increases the pumping power
required, which in turn increases the motor size. Because of their efficient
heat transfer characteristics, nanofluids can remove heat at a higher rate
than conventional coolants. Nanofluids can thus be thought of as a
replacement for conventional coolants, leading to a decrease in the size of
the coolant pumping motor.
Oil-based nanofluids containing silver nanoparticles could find application
in deep-hole drilling, where they could help improve the drilling penetration
rate and clean, lubricate, and cool the drill bit. Thus, nanofluids could
significantly improve drilling speeds and hence make it possible to extract
more oil (Phuoc and Lyons, 2007). Shen (2008) studied wheel wear and
tribological characteristics in wet, dry, and minimum quantity lubrication
(MQL) grinding of cast iron. Water-based alumina and diamond nanofluids
were applied in the MQL grinding process and the grinding results were
compared with those of pure water. Nanofluids demonstrated the benefits of
reducing grinding forces, improving surface roughness, and preventing
burning of the workpiece. In contrast to dry grinding, MQL grinding could
considerably lower the grinding temperature. Further studies are warranted
on tribological properties using nanofluids for a wider range of particle
loadings as well as on the erosion rate of radiator material in order to help
develop predictive models for nanofluid wear and erosion in engine systems.
10.4.3 Coolants in electronic devices
Miniaturization has been a major trend since the middle of the twentieth
century in the field of science and technology. This has led to a dramatic
increase in the power densities of integrated circuits and microprocessors.
This current trend is expected to continue in the future. Existing aircooling
system designs have reached their limit and liquid cooling systems are taking
over to fulfill the need for higher high heat transfer capacity required for
cooling high-performance electronic devices (Yu, 2007a). Water-based
nanofluids have been used as the working medium in a circular heat pipe
designed as a heat spreader to be used in a central processing unit (CPU) in a
notebook or a desktop computer. The results showed a significant reduction
