Driven by the ever-increasing desire to generate nanofluids via economic, single-step manufacturing procedures, a study published in Scientific Reports describes the potential of employing radiolysis to design durable, efficacious nanofluids with improved heat conduction for the first time.
Study: A novel approach for engineering efficient nanofluids by radiolysis. Image Credit: Sylverarts Vectors/Shutterstock.com
The Dawn of Nanofluids
Nanofluids are regarded as a plausible technological answer to the rapidly growing demands of the digital-focused world. In addition, nanofluids may prove to be the solution to the need for efficient coolants in nanoscale electronics to efficiently disperse the heat produced inside the systems and the heat produced in the fast-progressing data storage sector.
Originally examined as a unique coolant for removing heat in nuclear plants and the automobile sector, nanofluids are currently being widely researched for their prospective uses in geothermal power and medicinal industries.
What are Nanofluids?
Nanofluids can be considered molecular fluids composed of a homogeneous distribution of nanoparticles (NPs) in a typical coolant carrier fluid like oil, water, or ethylene glycol (C2H6O2).
Typical heat transferring fluids have a heat conductance of fewer than 1 Wm-1K-1 at ambient conditions, but metals and their respective oxides possess thermal conductivities that are about two or three orders of magnitude greater.
A nanoscale suspension of these metal NPs or their corresponding oxides in a typical coolant carrier fluid would therefore result in a considerable increase in the nanofluid's heat conduction.
Such an increase in heat conduction has been shown in experiment-based nanofluidics for a variety of nanofluids, including TiO2-C2H6O2, Al2O3-C2H6O2, CNT-C2H6O2, ZnO-H2O, CuO-H2O, Ag-H2O, and CNT-H2O. The replicable heat conduction improvement ranged from 7 to 18 percent compared to the host fluid of ethylene glycol or water.
Synthesis Approaches for Nanofluids
Thus far, two main techniques have been used to produce steady nanofluids: double and single-step procedures.
In the double-step technique, the NPs are generated by different nano-synthetic chemical or physical methods. Nanoparticles are then distributed in the thermal host fluid matrix with potentially an additional molecular surfactant to lessen their aggregation, thus limiting their Otswald-ripening equivalent aggregation.
On the flip side, in the single-step approach, nanoparticles are created immediately inside the host fluid. The single-step methods encompass microwave, evaporation, liquid solution pulsed laser ablation, sonochemistry, and electric arc discharge methodologies.
Focusing on Radiolysis
Radiolysis is widely known in the fields of radiobiology and radiochemistry. This paper, however, details and demonstrates the feasibility of employing radiolysis for the production of steady and efficacious nanofluids with increased heat conduction for the first time.
The cost-effective nature and mass production prospects are significant advantages of developing nanofluids through radiolysis.
Compared to other nanofluid synthesizing approaches, and as supported by published experimental findings, radiolysis seems to offer the benefits of simple processes, mass production, scalability, comparatively low energy input, and removing the need for vacuum conditions.
Applications of Nanofluids
According to the reported engineering and scientific research, the primary uses of nanofluids encompass heat exchange, heat extraction, cooling functions, electronics, automotive systems, cooling of data storing units, detergents, biomedicine solutions, deep excavation, and geothermal systems.
Findings of the Study
This work demonstrated the feasibility of constructing nanofluids based on Ag-C2H6O2 and Ag-H2O using g-radiolysis at doses ranging from 0.95 x 103-2.45 x 103 Gray. These nanofluids significantly increased thermal conductivity, which proved to be dosage sensitive.
Without optimization, the greatest thermal conductivity increase recorded was as large as 23.57 percent. The thermal conductivity improvement factor induced by Brownian motion was definitively demonstrated in a narrow temperature span of 25-50 °C.
The maximum heat conduction increase was seen on nanofluids containing silver NPs with a crystallographic structure, as predicted given the dosage sensitivity.
While these findings were observed in Ag-C2H6O2 and Ag-H2O, it is too early to draw any general conclusions. In the future, the examination of the reduction in heat conduction at greater dosages may be studied.
Maaza, M., Khamliche, T. et al. (2022). A novel approach for engineering efficient nanofluids by radiolysis. Scientific Reports, 12. Available at: https://doi.org/10.1038/s41598-022-14540-z
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