Nanofluids have many potentially heat transfer applications,[4] including microelectronics, fuel cells, pharmaceutical processes, and hybrid-powered engines,[5] engine cooling/vehicle thermal management, domestic refrigerator, chiller, heat exchanger, in grinding, machining and in boiler flue gas temperature reduction.
[7][8] Nanofluids also have special acoustical properties and in ultrasonic fields display shear-wave reconversion of an incident compressional wave; the effect becomes more pronounced as concentration increases.
[15] Thermal conductivity, viscosity, density, specific heat, and surface tension are significant thermophysical properties of nanofluids.
Parameters such as nanoparticle type, size, shape, volume concentration, fluid temperature, and nanofluid preparation method affect thermophysical properties.
[19][20] A biologically-based, environmentally friendly approach for the covalent functionalization of multi-walled carbon nanotubes (MWCNTs) using clove buds was developed.
[40][41] A 2013 study considered the effect of an external magnetic field on the convective heat transfer coefficient of water-based magnetite nanofluid experimentally under laminar flow regime.
In a fixed magnetic field, a light source illuminates the nanofluid, changing its colour depending on the cation concentration.
The so-called photonic eye is based on a magnetically polarizable nano-emulsion that changes colour when it comes into contact with a defective region in a sample.
Other nanolubricant approaches, such as magnesium silicate hydroxides (MSH) rely on nanoparticle coatings by synthesizing nanomaterials with adhesive and lubricating functionalities.
[51] Companies such as TriboTEX provide commercial formulations of synthesized MSH nanomaterial coatings for vehicle engine and industrial applications.
The Strategic Technology Office of the U.S. Defense Advanced Research Projects Agency (DARPA) is exploring military’s deployment of NFB in place of conventional lithium-ion batteries.
Particles are engineered to remain suspended indefinitely, comprising up to 80 percent of the liquid’s weight with the viscosity of motor oil.
An EV-battery sized fuel reservoir (80 gallons) was expected to provide range comparable to a conventional gasoline vehicle.
[56] A 30-lab study reported that "no anomalous enhancement of thermal conductivity was observed in the limited set of nanofluids tested in this exercise".
[58] Despite these apparently conclusive experimental investigations theoretical papers continue to claim anomalous enhancement,[59][60][61][62][63][64][65] particularly via Brownian and thermophoretic mechanisms.
[66] Experimental validation of these assertions came in 2018[67] Brownian diffusion as a cause for enhanced heat transfer is dismissed in the discussion of the use of nanofluids in solar collectors.