K.V. Sharma

Bio: K.V. Sharma is an academic researcher from Jawaharlal Nehru Technological University, Hyderabad. The author has contributed to research in topics: Nanofluid & Heat transfer. The author has an hindex of 40, co-authored 144 publications receiving 4616 citations. Previous affiliations of K.V. Sharma include Petronas & Universiti Teknologi Petronas.

Hybrid nanofluids preparation, thermal properties, heat transfer and friction factor – A review

Abstract: In the past decade, research on nanofluids has been increased rapidly and reports reveal that nanofluids are beneficial heat transfer fluids for engineering applications. The heat transfer enhancement of nanofluids is primarily dependent on thermal conductivity of nanoparticles, particle volume concentrations and mass flow rates. Under constant particle volume concentrations and flow rates, the heat transfer enhancement only depends on the thermal conductivity of the nanoparticles. The thermal conductivity of nanoparticles may be altered or changed by preparing hybrid (composite) nanoparticles. Hybrid nanoparticles are defined as nanoparticles composed by two or more different materials of nanometer size. The fluids prepared with hybrid nanoparticles are known as hybrid nanofluids. The motivation for the preparation of hybrid nanofluids is to obtain further heat transfer enhancement with augmented thermal conductivity of these nanofluids. This review covers the synthesis of hybrid nanoparticles, preparation of hybrid nanofluids, thermal properties, heat transfer, friction factor and the available Nusselt number and friction factor correlations. The review also demonstrates that hybrid nanofluids are more effective heat transfer fluids than single nanoparticles based nanofluids or conventional fluids. Notwithstanding, full understanding of the mechanisms associated with heat transfer enhancement of hybrid nanofluids is still lacking and, consequently it is required a considerable research effort in this area.

The Enhancement of Effective Thermal Conductivity and Effective Dynamic Viscosity of Nanofluids – A Review

Abstract: The determination of thermo-physical properties and especially thermal conductivity and viscosity were important for evaluating heat transfer coefficients either for single or two phase flow. The thermo-physical properties measurements and heat transfer observations were mostly obtained with nanoparticles above 10 nm. Various researchers measured and modelled for the determination of thermal conductivity and viscosity of nanofluids. Most of the investigators developed equations for the estimation of thermal conductivity and viscosity as a function of percentage volume concentration, temperature and sometimes with the consideration of particle size valid in their experimental range. Nanofluids are considered to have great potential for heat transfer enhancement and are applied in heat transfer processes. Many studies were carried out to investigate this phenomenon. The main aim of this study is to give a comprehensive review on the research progress on the enhancement of effective thermal conductivity and effective dynamic viscosity of nanofluids.

A review on applications and challenges of nanofluids

Abstract: Nanofluids are potential heat transfer fluids with enhanced thermophysical properties and heat transfer performance can be applied in many devices for better performances (i.e. energy, heat transfer and other performances). In this paper, a comprehensive literature on the applications and challenges of nanofluids have been compiled and reviewed. Latest up to date literatures on the applications and challenges in terms of PhD and Master thesis, journal articles, conference proceedings, reports and web materials have been reviewed and reported. Recent researches have indicated that substitution of conventional coolants by nanofluids appears promising. Specific application of nanofluids in engine cooling, solar water heating, cooling of electronics, cooling of transformer oil, improving diesel generator efficiency, cooling of heat exchanging devices, improving heat transfer efficiency of chillers, domestic refrigerator-freezers, cooling in machining, in nuclear reactor and defense and space have been reviewed and presented. Authors also critically analyzed some of the applications and identified research gaps for further research. Moreover, challenges and future directions of applications of nanofluids have been reviewed and presented in this paper. Based on results available in the literatures, it has been found nanofluids have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional fluids. This can be considered as one of the key parameters for enhanced performances for many of the applications of nanofluids. Because of its superior thermal performances, latest up to date literatures on this property have been summarized and presented in this paper as well. However, few barriers and challenges that have been identified in this review must be addressed carefully before it can be fully implemented in the industrial applications.

A Benchmark Study on the Thermal Conductivity of Nanofluids

Abstract: This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about the sample average with only few outliers. The thermal conductivity of the nanofluids was found to increase with particle concentration and aspect ratio, as expected from classical theory. There are (small) systematic differences in the absolute values of the nanofluid thermal conductivity among the various experimental approaches; however, such differences tend to disappear when the data are normalized to the measured thermal conductivity of the basefluid. The effective medium theory developed for dispersed particles by Maxwell in 1881 and recently generalized by Nan et al. [J. Appl. Phys. 81, 6692 (1997)], was found to be in good agreement with the experimental data, suggesting that no anomalous enhancement of thermal conductivity was achieved in the nanofluids tested in this exercise.

A review on hybrid nanofluids: Recent research, development and applications

Abstract: Researches on the nanofluids have been increased very rapidly over the past decade. In spite of some inconsistency in the reported results and insufficient understanding of the mechanism of the heat transfer in nanofluids, it has been emerged as a promising heat transfer fluid. In the continuation of nanofluids research, the researchers have also tried to use hybrid nanofluid recently, which is engineered by suspending dissimilar nanoparticles either in mixture or composite form. The idea of using hybrid nanofluids is to further improvement of heat transfer and pressure drop characteristics by trade-off between advantages and disadvantages of individual suspension, attributed to good aspect ratio, better thermal network and synergistic effect of nanomaterials. This review summarizes recent researches on synthesis, thermophysical properties, heat transfer and pressure drop characteristics, possible applications and challenges of hybrid nanofluids. Review showed that proper hybridization may make the hybrid nanofluids very promising for heat transfer enhancement, however, lot of research works is still needed in the fields of preparation and stability, characterization and applications to overcome the challenges.