P.P. Kulkarni

Bio: P.P. Kulkarni is an academic researcher from Bhabha Atomic Research Centre. The author has contributed to research in topics: Corium & Nanofluid. The author has an hindex of 9, co-authored 41 publications receiving 272 citations.

Measurement of volumetric thermal expansion coefficient of various nanofluids

Abstract: Experiments were carried out for studying volumetric thermal expansion behavior of various nanofluids in order to evaluate their potential application in heat removal systems employing natural convection as mode of heat removal. For this purpose, various nanoparticles such as Al2O3, CuO, SiO2 and TiO2 were used, which were suspended in the base fluid (water) by ultrasonication. All nanofluids had the same concentration of 1 wt %. Each nanofluid was heated from room temperature to a maximum of about 60°C and the increase in volume due to heat addition was recorded. The volumetric thermal expansion due to heating for each nanofluid was compared to that for the base fluid for same increase in the temperature. The volumetric thermal expansion coefficient was evaluated from the measured data. Surprisingly, it was found that the nanofluids have greater volumetric thermal expansion coefficients as compared to that of the base fluid. 1The text was submitted by the authors in English.

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.

Turbulent forced convection heat transfer and thermophysical properties of Mgo–water nanofluid with consideration of different nanoparticles diameter, an empirical study

Abstract: In the present paper results of an experimental study on thermal conductivity, dynamic viscosity and Nusselt number of turbulent forced convection of Magnesium Oxide–water nanofluid in a circular straight pipe is presented. The considered pertinent parameters are Reynolds number, nanoparticles volume fraction and nanoparticles diameter. The pure water and nanofluid with the nanoparticle volume fraction of 0.005, 0.01, 0.015, 0.02 and the nanoparticles diameter of 60, 50, 40 and 20 nm are considered. The experimental values of the thermal conductivity and the dynamic viscosity shows that traditional formulas underestimates these thermophysical parameters. Also the experimental results indicates that the existence of the nanoparticles in the pure water with all considered values of the nanoparticles volume fraction and diameter motivates the rate of heat transfer to increase. The nanofluids with higher volume fraction and smaller nanoparticles diameter results in higher Nusselt number.

Rheological and volumetric properties of TiO2-ethylene glycol nanofluids

Abstract: Homogeneous stable suspensions obtained by dispersing dry TiO2 nanoparticles in pure ethylene glycol were prepared and studied Two types of nanocrystalline structure were analyzed, namely anatase and rutile phases, which have been characterized by scanning electron microscopy The rheological behavior was determined for both nanofluids at nanoparticle mass concentrations up to 25%, including flow curves and frequency-dependent storage and loss moduli, using a cone-plate rotational rheometer The effect of temperature over these flow curve tests at the highest concentration was also analyzed from 28315 to 32315 K Furthermore, the influence of temperature, pressure, nanocrystalline structure, and concentration on the volumetric properties, including densities and isobaric thermal expansivities, were also analyzed