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heat-transfer-and-friction-factors
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Numerical investigation of rectangular-cut twisted tape insert on performance improvement of heat exchangers
, Article International Journal of Thermal Sciences ; Volume 138 , 2019 , Pages 75-83 ; 12900729 (ISSN) ; Esfahani, J. A ; Sharif University of Technology
Elsevier Masson SAS
2019
Abstract
A numerical analysis has been performed to investigate the flow structure and thermal hydraulic performance of turbulent flow through circular tube equipped with twisted tapes with different cut shapes. The geometries of cuts are rectangular with different cut ratios 0.25
Cu-water nanofluid flow and heat transfer in a heat exchanger tube equipped with cross-cut twisted tape
, Article Powder Technology ; Volume 339 , 2018 , Pages 985-994 ; 00325910 (ISSN) ; Esfahani, J. A ; Sharif University of Technology
Elsevier B.V
2018
Abstract
This paper presents a numerical analysis for Cu-water nanofluid flow through a circular duct inserted with cross-cut twisted tape with alternate axis (CCTA). Three dimensional (RNG) k − ϵ turbulence model is applied to simulate this problem. All simulations are performed for plain tube and nine different CCTA geometries in the range of width ratio (b/w) from 0.7 to 0.9, length ratio (s/w) from 2 to 2.5, Reynolds numbers in the range of 5000 to 15,000 and volume fraction of nanoparticles from 0 to 1.5%. The calculated results indicate that the swirl flow created by CCTA is transferred from the tube core to the near wall regions. This results in higher fluid mixing, which enhances heat...
CFD modeling of turbulent convection heat transfer of nanofluids containing green functionalized graphene nanoplatelets flowing in a horizontal tube: Comparison with experimental data
, Article Journal of Molecular Liquids ; Volume 269 , 2018 , Pages 152-159 ; 01677322 (ISSN) ; Mallah, A. R ; Hosseini, M ; Ahmadi, G ; Kazi, S. N ; Dabbagh, A ; Yeong, C. H ; Ahmad, R ; Yaakup, N. A ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In this research, a series of numerical simulations were conducted utilizing computational fluid dynamics (CFD) software in order to predict the heat transfer performance of queues nanofluids containing clove-treated graphene nanoplatelets (CGNPs) flowing in a horizontal stainless steel heated pipe. The GNPs were covalently functionalized with clove buds using free radical grafting reaction using an eco-friendly process. The advantage of this synthesis method was that it did not use hazardous acids, which are typically used in traditional treatment methods of carbon nanostructures. The thermo-physical properties of the aqueous nanofluids obtained experimentally were used as inputs for the...