Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer (MHMT'24)
London, United kingdom – April 11 – 13, 2024
Paper No. ENFHT 336
DOI: 10.11159/enfht24.336

Propylene Glycol:Water-Based Nanofiber And Spherical Ag Nanofluids
As Advanced Working Fluids
Marco A. Marcos1,2*, Javier P. Vallejo3, S. M. Sohel Murshed2, Luis Lugo1
1

Departamento de Física Aplicada, Grupo GAME, Universidade de Vigo, 36310 Vigo, Spain
mmarcosm@uvigo.gal; luis.lugo@uvigo.gal
2IDMEC, Instituto Superior Técnico, University of Lisbon, Lisbon 1049-001, Portugal
smurshed@tecnico.ulisboa.pt
3Centro Universitario de la Defensa en la Escuela Naval Militar, Grupo InTeam, 36920 Marín, Spain
jvallejo@cud.uvigo.es

Extended Abstract
Greenhouse gas emissions, especially those of carbon dioxide (CO2), are considered one of the main causes of climatechange and have become one of the most important environmental problems worldwide. Carbon dioxide has been the main
source of extreme environmental pollution and has detrimental consequences on human life, regardless of whether theeconomy is developed [1]. In this regard, heat transfer plays a key role for both industrial and domestic processes. Improving
the efficiency of heat exchangers can result in lower energy consumption and therefore a reduction in CO2 emissions. Aninteresting way to improve the efficiency of heat exchangers is through the use of nano-enhanced thermal fluids, also termed
nanofluids [2]. These materials are based on dispersions of nanoparticles in a base fluid and are characterized by exhibitingsuperior thermal properties such as the thermal conductivity [3].
This study presents the thermophysical properties of nanofluids based on a mixture of propylene glycol:water (PG:W)
with a mass ratio 20:80. The selected nanoadditives were silver nanoparticles with two shapes: nanofibers of 3050 nm wide(AgNF) and spherical nanoparticles (AgNP) with a diameter of 2550 nm. There were designed two 0.10 wt.% mononanofluids (with AgNF and AgNP) and a 0.10 wt.% hybrid nanofluid (with a AgNF:AgNP mixture at 1:1 mass ratio). Inorder to check the temporal stability of the dispersions, the hydrodynamic size of the colloids have been observed throughdynamic light scattering under static conditions and also after shaking it for 30 s before taking measurements. The results
showed good stability of the dispersions after 30 days. Isobaric heat capacity and density were determined throughtemperature modulated heat differential scanning calorimetry and vibrating U-tube, respectively. Thermal conductivity wasstudied by the transient hot wire technique in the temperature range from 283 to 333 K with average increases of 8% for the0.10 wt.% AgNF nanofluid (the highest increase between those analyzed). The rheological behavior was analyzed byrotational rheometry between 283 and 323 K. The designed dispersions preserve the Newtonian behavior of the base fluid
and the average viscosities show slight increases with respect to the base fluid. As an example, these increases reach 0.9%
for the 0.10 wt.% AgNF:AgNP hybrid nanofluid.

Acknowledgements
Grant PID2020-112846RB-C21 funded by MCIN/AEI/10.13039/501100011033. M.A.M. acknowledges the financial
support by the Ministerio de Universidades (Spain) under budgetary implementation 33.50.460A.752 and by the EuropeanUnion NextGenerationEU/PRTR through a Margarita Salas postdoctoral contract of the Universidade de Vigo (Spain). J.P.V.
thanks the Defense University Center at the Spanish Naval Academy (CUD-ENM) for all the support provided for thisresearch.

References[1] P. Ponce, and S.A.R. Khan. A causal link between renewable energy, energy efficiency, property rights, and CO 2
emissions in developed countries: a road map for environmental sustainability. Environ. Sci. Pollut. Res., 28, 2021,
pp.37804-37817.
[2] N.S. Pandya, H. Shah, M. Molana, & A. K. Tiwari, Heat transfer enhancement with nanofluids in plate heat exchangers:
A comprehensive review. Eur. J. Mech. B Fluids, 81, 2020, 173-190.

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[3] J.P. Vallejo, L. Ansia, U. Calviño, M.A. Marcos, J. Fernández-Seara, & L. Lugo. Convection behaviour of mono andhybrid nanofluids containing B4C and TiB2 nanoparticles. Int. J. Therm. Sci., 189, 2023, 108268.

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