Modeling of effect of nanoparticle shape on heat transfer of nanofluids in two phase flow

Aminian, Mohammadreza (2017) Modeling of effect of nanoparticle shape on heat transfer of nanofluids in two phase flow. Masters thesis, University of Mohaghegh Ardabili.

Preview

Text (مدلسازی اثر شکل نانوذرات روی انتقال حرارت نانوسیالات در جریان دو فازی) Mohammadreza Aminian.pdf Download (1MB) | Preview

Abstract

The use of nanoparticles in thermal systems improves the performance and reduces the size of the systems. The development of nanofluids requires proper cognition and understanding of their behavior and the effective parameters. The type of base fluid and nanoparticle, the volume fraction of nanoparticles, the shape and diameter of nanoparticles, etc. are some of the influential parameters in the current of nanofluids which can be mentioned. In this study, parameters such as nanofluid flow regime, composition percentage of nanoparticle, nanoparticle type and pipe placement according to the effect of nanoparticle shape on the thermal transfer performance of the nanofluids system using a two-phase mixture model were discussed and numerically investigated. In the first part, which included a general study of the effect of nanoparticle shape on thermal performance and characteristics of nanofluids flow, the results showed that by increasing Reynolds number and volume fraction of nanoparticles, the heat transfer coefficient and Nusselt number increase for nanoparticles with different shape of nanoparticles and however, the incremental trend decreases for nanofluids with the nanoparticles shape of platelet, cylindrical, blade, brick and ultimately spherical nanoparticles, respectively. Also, the pressure drop and the coefficient of friction as the features of the nanofluid flow can change by the change of shape and increasing the Reynolds number, which tends increase for the pressure drop and decreases for the coefficient of friction. In the second part, the effect of the nanoparticles type was investigated, which results showed that nanofluids containing copper oxide had better performance than nanofluids containing aluminum oxide, but this advantage, under the working conditions of the Reynolds number of less than 1500, in the different volume fractions for nanofluids containing nanoparticles with a platelets aluminum oxide, can have a reverse ratio compared to nanoparticles containing copper oxide nanoparticles with a spherical shape. In the third section, two vertical and horizontal positioning conditions of the nanofluids carrier pipe were investigated. The results in this section indicated an increase in the heat transfer in the vertical tube compared to the horizontal pipe. Also, in this section nanofluids containing nanoparticles with brick shape were more sensitive and had a higher thermal performance than their horizontal position. Finally, two correlations have been presented to calculate the Nusselt number of nanofluids in two laminar and turbulent flow regimes. Keywords: Heat Transfer, CFD, Nanoparticle Shape, Two Phase Modeling, Nanofluid

Actions (login required)

View Item