Dispersion and thermal conductivity of TiO 2 /water nanofluid
- PDF / 815,438 Bytes
- 6 Pages / 595.276 x 790.866 pts Page_size
- 47 Downloads / 207 Views
(0123456789().,-volV)(0123456789(). ,- volV)
Dispersion and thermal conductivity of TiO2/water nanofluid Effects of ultrasonication, agitation and temperature Karen Cacua1,2 • S. M. Sohel Murshed3
•
Elizabeth Pabo´n1 • Robison Buitrago2
Received: 1 August 2019 / Accepted: 6 September 2019 Ó Akade´miai Kiado´, Budapest, Hungary 2019
Abstract Stability of nanofluids is one of the major challenges for their real-world applications and benefits. Although ultrasonication and addition of surfactant are commonly used to obtain better stability of nanofluids, there is a lack of adequate knowledge on the effects of various parameters and duration of ultrasonication as well as some other influences of surfactant. The effect of ultrasonication on the dispersion of nanoparticles and agitation as well as temperature on the thermal conductivity measurements of aqueous TiO2 nanofluids was experimentally studied. An UV–Vis absorbance analysis was performed to identify the degree of dispersion of nanoparticles (stability) and also to determine the right amplitude as well as the duration of the ultrasonication. In addition, agitation of nanofluids during the measurement of thermal conductivity showed a serious adverse effect as significant fraction of nanoparticles adhered to both the probe and the wall of the sample container. Furthermore, present results showed that the enhanced thermal conductivity of this nanofluid further increases noticeably with increasing temperature. Keywords Nanofluids Stability Agitation Ultrasonication Nanoparticles Thermal conductivity
Introduction In recent years, nanofluids have received huge interest from researchers and industrial people and thus extensive research works have been performed on various areas of these engineered fluids [1–3]. Despite some good developments in some areas, the real usages of nanofluids in applications particularly in thermal management systems remain very challenging and beyond the reach mainly due to not yet well-understanding the underlying mechanisms and also not having long-term stability of nanofluids [4, 5]. & S. M. Sohel Murshed [email protected] 1
Advanced Material Science Group, Universidad Nacional de Colombia, Calle 59A 63-20, Medellı´n, Colombia
2
Faculty of Engineering, Advanced Material Science Group, Instituto Tecnolo´gico Metropolitano, Calle 54A No. 30-01, Medellı´n, Colombia
3
Centre for Innovation, Technology and Policy Research, Instituto Superior Te´cnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
In spite of nanofluids exhibiting superior thermophysical properties such as thermal conductivity, thermal diffusivity, heat capacity and viscosity, there remains controversy and serve inconsistencies in reported results on these properties [3, 6–11]. If nanoparticles are not well-dispersed and stable for long period in host fluids, nanofluids can neither exhibit desired high thermophysical properties nor can be used in real applications particularly in closed systems. Thus, it is of great importance to make sure tha
Data Loading...
