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Spiros V. Paras

Bio: Spiros V. Paras is an academic researcher from Aristotle University of Thessaloniki. The author has contributed to research in topics: Two-phase flow & Reynolds number. The author has an hindex of 27, co-authored 67 publications receiving 2368 citations.


Papers
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TL;DR: In this paper, the efficacy of nanofluids as coolants is investigated in industrial heat exchangers, where large volumes of nano-fluids are necessary and turbulent flow is usually developed.

314 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of the use of a nanofluid in a miniature plate heat exchanger (PHE) with modulated surface has been studied both experimentally and numerically.

235 citations

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TL;DR: In this article, the effect of liquid properties on the performance of bubble column reactors with fine pore spargers was studied. But the authors focused on the effect on the average gas holdup values, bubble size distributions and Sauter diameters and were consistent with existing physical models on coalescence/breakage.

167 citations

Journal ArticleDOI
TL;DR: In this article, the effect of liquid properties and pore size on the initial bubble size distribution of a bubble column equipped with a fine pore sparger was studied, and a new correlation regarding the prediction of the initial mean Sauter diameter of bubbles formed from porous spargers at the homogeneous regime was formulated and found to be in good agreement with available data.

142 citations

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TL;DR: In this article, the characteristics of films flowing inside a vertical pipe are studied experimentally using an accurate wire conductance technique, and the mean film thickness is measured over the Re range 509-13,090.

122 citations


Cited by
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Journal ArticleDOI
TL;DR: It has been found nan ofluids have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional fluids, which can be considered as one of the key parameters for enhanced performances for many of the applications 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.

1,558 citations

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TL;DR: In this article, the authors investigated the effects of nanofluids on the performance of solar collectors and solar water heaters from the efficiency, economic and environmental considerations viewpoints, and made some suggestions to use the nanoparticles in different solar thermal systems such as photovoltaic/thermal systems, solar ponds, solar thermoelectric cells, and so on.

1,069 citations

Journal ArticleDOI
TL;DR: In this article, the stability of nanofluids is discussed as it has a major role in heat transfer enhancement for further possible applications, and general stabilization methods as well as various types of instruments for stability inspection.

948 citations

Journal ArticleDOI
TL;DR: In this paper, a combination of the aggregation mechanism with the Maxwell and Bruggeman models gives a good prediction of the effective thermal conductivity of the nanofluids, which can be given as eta/eta(0) - 1 = 10.6 phi + (10.6 �i)(2).

423 citations

Journal ArticleDOI
TL;DR: In this paper, the authors summarized the important published articles on the enhancement of the convection heat transfer in heat exchangers using nanofluids on two topics: theoretical and experimental results for the effective thermal conductivity, viscosity and the Nusselt number reported by several authors.
Abstract: The purpose of this review summarizes the important published articles on the enhancement of the convection heat transfer in heat exchangers using nanofluids on two topics. The first section focuses on presenting the theoretical and experimental results for the effective thermal conductivity, viscosity and the Nusselt number reported by several authors. The second section concentrates on application of nanofluids in various types of heat exchangers: plate heat exchangers, shell and tube heat exchangers, compact heat exchangers and double pipe heat exchangers.

421 citations