Nanofluids are nanoscale colloidal suspensions containing condensed nanomaterials. Nanofluids have been found to possess enhanced thermos-physical properties such as thermal conductivity, thermal diffusivity, viscosity, and convective heat transfer coefficients compared to those of base fluids like oil or water. Boron Nitride (BN) nanoparticles - due to its high thermal conductivity, appropriate thermal expansion coefficient, high electrical insulation and high mechanical strength is a promising additive in traditional heat exchange fluids. In this work we synthesised Boron Nitride (BN) nanoparticles by hydrothermal method and the nanoparticles are characterized by XRD, EDAX and SEM. Nanofluids were prepared by different weight fractions of the nanoparticles in different ratio of water and Ethylene Glycol (EG) solution. Physiothermal properties of the fluids at different temperatures were investigated and the same is reported.

Velmurugan V

Centre for Nanotechnology Research

Vellore Campus

Nirmala Grace A

Bharathithasan I

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Indian Journal of Science and Technology

Applied Surface Science

Green synthesis of graphene/Ag nanocomposites

In this article, the effect of Carbon Nanotube (CNT) concentration and agitation on the heat transfer rate has been studied during immersion quenching in CNT nanofluids. For this purpose, CNT nanofluids were prepared by suspending chemically treated CNTs (TCNT) at four different concentrations in deionized (D.I) water without using any surfactant. Quench probes with a diameter of 20 mm and a length of 50 mm were machined from 304L stainless steel (SS) and quenched in water and CNT nanofluids with the CNT concentration ranging from 0.25 to 1.0 wt.%. The heat flux and temperature at the quenched surface were estimated based on the Inverse Heat Conduction (IHC) method using the temperature data recorded at 2 mm below the probe surface during quenching. The computation results showed that the peak heat flux increased with an increase in the CNT concentration up to 0.50 wt.% and started decreasing with further increase in the CNT concentration. The enhanced heat transfer performance of CNT nanofluids during quenching at lower concentration of CNTs is attributed to their higher effective thermal conductivity. The reduced heat transfer performance of CNT nanofluids having higher concentration of CNTs is due to the increased viscosity of CNT nanofluids. The effect of agitation on heat transfer rate during quenching has also been studied in this work by stirring the CNT nanofluid prepared with 0.50 wt.% of CNTs which recorded the maximum peak heat flux among the four concentrations. The effect of CNT nanofluid agitation was counter-intuitive and resulted in decreased heat transfer rate with the increase in agitation rate. © 2010 Elsevier Ltd. All rights reserved.

International Journal of Heat and Mass Transfer

Effect of CNT concentration and agitation on surface heat flux during quenching in CNT nanofluids

Journal of Applied Physics

Experimental investigation on thermal conductivity of nanofluids containing graphene oxide nanosheets

We report for the first time, the synthesis of highly stable exfoliated graphene based nanofluids with water and ethylene glycol as base fluids with out any surfactant and the subsequent studies on their thermal and electrical conductivities. Graphene was synthesized by thermal exfoliation of graphene oxide at 1050 °C in Ar atmosphere. The as-synthesized graphene has been suitably functionalized and further dispersed it in the base fluids without any surfactant. Thermal and electrical conductivities of these nanofluids were measured for varying volume fractions and at different temperatures. An enhancement in thermal conductivity by about 14% has been achieved at 25 °C with deionized water (DI) as base fluid at a very low volume fraction of 0.056% which increases to about 64% at 50 °C. Electrical conductivity measurements for these nanofluids indicate an enormous enhancement at 25 °C for a volume fraction of 0.03%in DI water. © 2010 American Institute of Physics.

Investigation of thermal and electrical conductivity of graphene based nanofluids

A study on stability and thermophysical properties (density and viscosity) of Al2O3 in water nanofluid

Synthesis and Physiothermal Analysis of Boron Nitride Based Nanofluid

Journal	Indian Journal of Science and Technology
Publisher	Indian Society for Education and Environment
ISSN	0974-6846
Open Access	No