Remarkable Thermal Conductivity Enhancement in Carbon-Based Ionanofluids: Effect of Nanoparticle Morphology

Abstract

Transfer of the excellent intrinsic properties of individual carbon nanoparticles into real-life applications of the corresponding heat transfer fluids remains challenging. This process requires identification and quantification of the nanoparticle–liquid interface. Here, for the first time, we have determined geometry and properties of this interface by applying transmission electron cryomicroscopy (cryo-TEM). We have systematically investigated how the particle morphology of carbon-based nanomaterials affected the thermal conductivity, specific isobaric heat capacity, thermal diffusivity, density, and viscosity of ionanofluids and/or bucky gels, using a wide range of fillers, especially single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs), both with extreme values of aspect ratio (length to diameter ratio) from 150 to 11 000. Accordingly, hybrid systems composed of various carbon nanomaterials and ionic liquid, namely 1-ethyl-3-methylimidazolium thiocyanate [EMIM][SCN], were prepared and characterized. Most of the analyzed nanodispersions exhibited long-term stability even without any surfactant. Our study revealed that the thermal conductivity could be remarkably improved to the maximum values of 43.9% and 67.8% for ionanofluid and bucky gel (at 1 wt % loadings of MWCNTs and SWCNTs), respectively, compared to the pristine ionic liquid. As a result, the model proposed by Murshed and co-workers has been improved for realistic description of the concentration-dependent thermal conductivity of such hybrid systems. The obtained results undoubtedly indicate the potential of ionanofluids and bucky gels for energy management.

Optimization of Thermophysical and Rheological Properties of Mxene Ionanofluids for Hybrid Solar Photovoltaic/Thermal Systems

“…However, such an addition induced a substantial increase in viscosity that affects the other properties like pumping power, surface tension etc. Another criterion, nanoparticle morphology, presented by Jozwiak et al [ 24 ] analyzed the enhancement of thermal conductivity in carbon-based ionanofluids. With increased aspect ratio and surface area of the dispersed carbon nanotubes, the thermal characteristics of the ionanofluids showed a substantial increase.…”

Thermal Conductivity and Viscosity of Ionanocolloids for Applications in Thermal Energy Systems

“…of MWCNT was responsible to enhance thermal conductivity of [C4mim][NTf2] approximately 26 %. The impact of nanoparticle type has been reported as more significant significant than concentration [10], and it is conditioned by the thermal conductivity of the nanoparticle, which is lower for for the metal oxides and higher for metals, graphene and carbon nanotubes [11]. Regarding the ionic liquid structure, both both cation and anion influence on thermal conductivity, but there is an agreement between the authors that the anion nature is more impactful.…”

Effect of ultrasonication time on microstructure, thermal conductivity, and viscosity of ionanofluids with originally ultra-long multi-walled carbon nanotubes

“…Recently, we studied the thermophysical properties of low-viscosity INFs consisting of 1-ethyl-3-methylimidazolium thiocyanate [Emim][SCN] and MWCNTs (in-house grown via chemical vapor deposition, CVD) with high aspect ratios of 6300 and 11000. We discovered an extraordinary improvement of thermal conductivity up to 43.9% for 1 wt% MWCNTs [41] . For the first time, we determined the thickness of the interfacial nanolayer (ca.…”