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Nanomaterials and nanotechnology systems come in many forms. A nanofluid is a fluidic system that contains a colloidal suspension of nanoparticles. In this article, we look at these nanofluids and what potential they have in the automotive industry.
The nanoparticles in a nanofluid can be of any composition, as the definition is very broad. However, the medium that they are suspended in does need to be a base fluid; i.e., it needs to be a continuous phase fluid that can flow.
The base fluids that hold the colloidal suspension of nanoparticles can be either aqueous or oleic in nature, but it is often the choice of nanoparticle within the fluid that brings about specific enhancements to the base fluid’s properties.
To obtain an efficient and well-dispersed system, the nanoparticles used need to fall in line with most regulatory definitions - typically, they should be anywhere between 1 and 100 nm in diameter. These nanoparticle and base fluid systems are known to have excellent heat transfer, lubricating, and acoustic properties that have made them usable across many industry sectors, including the automotive industry.
Nanofluids can be thought of as a single-phase system, where the properties of a single-phase fluid are a function of the properties of both the nanoparticles within the system and their concentration. However, some estimations use a two-component model where the flow properties (Reynolds number, etc.) of the base fluid also affect the properties of the whole system (as well as the nanoparticle properties arising from the concentration and composition).
There are a number of methods that can be used to produce nanofluids, and the most common include dispersion methods using an ultrasonic probe/bath, evaporation techniques, gas dispersion techniques, chemical vapor condensation, and chemical precipitation methods.
Automotive Applications of Nanofluids
In the automotive sector, there are two main areas where nanofluids are finding some use. These are nanoparticle-enhanced lubricants and liquid coolants in air-cooled radiator systems, both of which utilize the efficient heat transfer properties of various types of nanofluids.
Lubricants are used throughout the automotive industry in areas ranging from the brake systems to the engine. As these nanofluids are used in energy-intensive environments, they need to be able to withstand high temperatures and shear stresses.
Nanofluids composed of nanoparticles in lubricant base oils are commercially available and are known to reduce the wear on the system (and on the base oil when the nanofluid is compared to the pure base fluid). They are known to provide both enhanced lubricating properties (where the mechanical parts glide more smoothly over the nanoparticles) and heat-transfer properties (where the high heat generated in the lubricant from the mechanical system is more efficiently dissipated).
The latter property helps to increase the longevity of both the base fluid system and the mechanical system due to a lower amount of thermal degradation occurring over time.
The other big application area is using nanofluids as a heat-dissipating coolant fluid in some of the radiator systems used in automotive engines. Automotive engines are known to produce a lot of residual heat during the fuel combustion processes, and this heat needs to be dissipated, and the engines subsequently cooled. If this is not done, the engine could overheat and cause expensive and/or long-term damage, to the engine, the lubricants used within them, and the surrounding metal parts.
In many engines, an automotive coolant composed of ethylene glycol and water is used to absorb heat from the engine before it passes into the air radiator, where the liquid is cooled. Nanofluids have also emerged recently as a fluid that can be used in place of these mixtures and can utilize their much better heat transfer properties over the status quo.
Automotive engines are getting more powerful year on year (especially in high-end automobiles), and many coolants are starting to become less efficient, so nanofluids are now seen as a potential route for improving the cooling ability of engines, as well as helping to simultaneously contribute to a better fuel economy and lesser nitrous oxide emissions that come from a more efficient engine.
Unlike many of the water-based fluids used, the oleic-based nanofluids can also be used to remove the heat on the electronic components within the engine, and throughout the car, as this is another area of automobiles that is now more prevalent in the modern-day car than ever before. All these changes to automobiles have meant that new cooling fluids need to be found to keep up with the demands of the engine, and nanofluids are seen as one of the potential answers.
Sources and Further Reading
- “PERFORMANCE ANALYSIS OF NANOFLUID BASED LUBRICANT”- Sajumon K. T., International Journal of Innovative Research in Science, Engineering and Technology, 2013
- “On the Nanofluids Application in the Automotive Radiator to Reach the Enhanced Thermal Performance: A Review”- Molana M., American Journal of Heat and Mass Transfer, 2017, DOI: 10.7726/ajhmt.2017.1015