The behaviour of plasma-functionalized graphene nanoflake nanofluids during phase change from liquid water to solid ice
- 19 August 2020
- journal article
- research article
- Published by IOP Publishing in Nanotechnology
- Vol. 31 (45), 455703
- https://doi.org/10.1088/1361-6528/abaae0
Abstract
Emerging nanofluid-based technologies for cooling, transport, and storage applications have previously been enhanced through the use of graphene nanoflake (GNF) nanofluids. Many of the beneficial effects of GNFs have now been documented, though little work has yet been completed to characterize the morphological behaviour of GNF nanofluids both during and after the phase change process. In this study, the crystallization behaviour of sessile water droplets was evaluated for two plasma-functionalized, hydrophilic GNF concentrations (20 and 100 ppm) at three driving force temperatures (-5 degrees C, -10 degrees C, and -20 degrees C). At low driving forces, the GNFs were wholly expelled from the solid matrix due to low crystallization velocities. At high driving forces, more rapid crystallization rates resulted in the entrapment of GNFs within the air bubbles and inter-dendritic spaces of the solid droplet. However, individual particle dispersion was not achieved within the solid matrix at any driving force. Furthermore, for all experimental conditions, the functionalized GNF clusters which formed during freezing did not disperse spontaneously upon melting as drying-like effects may have altered the attraction properties of their surfaces and destabilized the suspension. Compared to previous studies using multi-walled carbon nanotubes, the GNFs were found to have higher liquid mobility at the solid front, provide less resistance to that front as it ascended, and be better dispersed after melting. These effects may have been geometrical; the square nanoflake geometry does not result in any physical particle entanglement.Keywords
Funding Information
- Natural Sciences and Engineering Research Council of Canada
This publication has 42 references indexed in Scilit:
- Role of PCM based nanofluids for energy efficient cool thermal storage systemInternational Journal of Refrigeration, 2013
- Measuring the Effect of Multi-Wall Carbon Nanotubes on Tetrahydrofuran–Water Hydrate Front Velocities Using Thermal ImagingCrystal Growth & Design, 2013
- Experimental Study on Solidification Behavior of Carbon Nanotube NanofluidAdvanced Materials Research, 2010
- Graphene Based Electrochemical Sensors and Biosensors: A ReviewElectroanalysis, 2010
- The effects of temperature, volume fraction and vibration time on the thermo-physical properties of a carbon nanotube suspension (carbon nanofluid)Nanotechnology, 2008
- Experimental Verification of Morphological Instability in Freezing Aqueous Colloidal SuspensionsPhysical Review Letters, 2008
- Morphological instability in freezing colloidal suspensionsProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2006
- On the behaviour of foreign particles at an advancing solid-liquid interfaceJournal of Crystal Growth, 1989
- The influence of gravity on the solidification of a dropJournal of Crystal Growth, 1987
- Air Bubbles in IceProceedings of the Physical Society, 1961