BIBLIOS

Document type
Conference papers

Document subtype
Extended abstract/Short paper

Title
Effects of agitation and sonication on dispersion and thermal conductivity of aqueous TiO2 nanofluids

Participants in the publication
Karen Cacua (Author)
F.E.B. Bioucas (Author)
CQE
S.M.S. Murshed (Author)
Dep. Química e Bioquímica
CQE
Maria José V. Lourenço (Author)
Dep. Química e Bioquímica
CQE
Fernando J. V. Santos (Author)
Dep. Química e Bioquímica
CQE
Carlos Nieto de Castro (Author)
Dep. Química e Bioquímica
CQE

Summary
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 use of nanofluids in potential applications particularly in thermal management systems remain very challenging and beyond reach mainly due to not yet understanding the underlying mechanisms and also not able to have long-term stability of prepared nanofluids [1]. 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 application particularly in close systems. Thus, it is of great importance to make sure that the added nanoparticles are properly (homogenously) dispersed in base fluids and nanofluids have as long stability. However, it is very challenging to achieve such long-term stability as many factors such as nanofluids preparation, nanoparticles types, size shapes, purity and degree of agglomerations as well as properties of base fluids are involved in this process. Various techniques, which include sonication, surfactant addition, agitation, and surface treatment of nanoparticles are commonly employed for better stability of sample nanofluids. However, most of the cases nanofluids are undergone sonication as well as having addition of various surfactants into them. Both of these means need to be carefully studied and understood before applying to sample nanofluids preparation for their better stability and properties without changing the chemistry of nanofluids and the original structures of nanoparticles [4-5]. One the one hand, addition of surfactant should be avoided as it can change the chemical composition and some properties of the nanofluids at different conditions (temperature and pressure) besides making nanofluids a three-phasic (nanoparticles, base fluids, surfactant) complex system. In case surfactant is to be used, its adverse effects due to adding wrong and excessive amount (must not exceed its critical micelle concentration limit) need to be accounted for. On the other hand, though ultrasonication is most widely used in nanofluids studies, there is a lack of adequate knowledge on the effects of its various parameters and duration of use. For instance, the effects of amplitudes, frequency, power settings etc of (ultra) sonicator and its duration of use on the samples and their properties particularly on thermal conductivity are neither well understood nor carefully studied. Therefore, this study aims to identify the influence of sonication and agitation on the dispersion of TiO2 nanoparticles and the thermal conductivity of their water-based nanofluids.

Editor(s)
S. M. Sohel Murshed, C. A. Nieto de Castro and Enrique Juliá


Institution
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DE LISBOA

Event
1st European Symposium on Nanofluids (ESNf2017)

Publication Identifiers
ISBN - 9789729665356

Address
Lisbon, Portugal

Organizers
Centro de Química Estrutural, Faculdade de Ciências da Universidade de Lisboa

Publisher
Faculdade de Ciências da Universidade de Lisboa

Collection
Abstract Book



Document Identifiers
URL - http://esnf2017.campus.ciencias.ulisboa.pt/

Keywords
Nanofluids Thermal conductivity Stability Ultrasonication Stirrer Nanoparticles TiO2