Experimental and Numerical Investigation on Non-Newtonian Nanofluids Flowing in Shell Side of Helical Baffled Heat Exchanger Combined with Elliptic Tubes

Abstract

Abstract:In this paper, an aqueous solution of xanthan gum (XG) at a weight fraction as high as 0.2% was elected as the non-Newtonian base liquid, the multi-walled carbon nanotubes (MWCNTs) dispersed into non-Newtonian XG aqueous at different weight factions of MWCNTs was prepared. Convection heat transfer of non-Newtonian nanofluids in the shell side of helical baffled heat exchanger combined with elliptic tubes has been investigated experimentally and numerically using single-phase flow model. Results showed that the enhancement of the convective heat transfer coefficient increases with an increase in the Reynolds number and the nanoparticle concentration. For nanofluids with 0.2 wt %, 0.5 wt % and 1.0 wt % MWCNTs, the Nusselt number, respectively, increases by 11%, 21% and 35% on average at the same Reynolds number, while the comprehensive thermal performance factors are 3%-5%, 15%-17% and 24%-26% higher than that of base fluid at the same volume rate. A remarkable heat transfer enhancement can be obtained by adding MWCNTs into XG aqueous solution based on thermal resistance analysis. Correlations have been suggested for the shell-side Nusselt number and friction factor of non-Newtonian nanofluids in the helical baffled heat exchanger with elliptic tubes. Good agreements existed between corrections and experimental data.

Characterization and Control for the Laminar Flow of Liquid Polyurethane System in a Wide Angle Diffuser with Transversely Arrayed Obstacles

“…Various non-Newtonian fluids such as polymeric systems display viscoelastic behaviors, but so far only a few available literatures have been published either for the creeping flow past a single cylinder or over a periodic transverse array of cylinders across the main flow, which implies that the viscoelastic effects have not been well investigated as they are regarded as minor in the present flow configuration [2], but so far the researches on numerical analyses have been much published in the category of rheology using the index of power law [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Some of them manifested various physics related with flow such as drag coefficient, vortex shedding, heat transfer, etc., around single shape or many figures of circular or elliptic cylinders [18,19]. However, it is hard to find an investigation on the flow uniformity and the mixing characteristics through a nozzle or a diffuser containing multiple bodies of repetitive configurations.…”

Heat Transfer and Entropy Generation Abilities of MWCNTs/GNPs Hybrid Nanofluids in Microtubes

“…However, hybrid nanofluids have shown further improvement in thermophysical properties and characteristics because of the synergy of two or more kinds of nanoparticle materials. This finding has motivated researchers to prepare novel hybrid nanofluids physically—by dispersing different prepared nanoparticle materials—or chemically—by synthesizing nanocomposite particles and then dispersing them in a base fluid [ 1 , 2 , 3 , 4 , 5 ].…”

Analysis of Flow Characteristics and Pressure Drop for an Impinging Plate Fin Heat Sink with Elliptic Bottom Profiles

“…Liang et al [30] carried out a novel optimal design of an air-to-air heat exchanger with cross-corrugated triangular ducts employing particle swarm optimization algorithm, considering the Colburn factor, friction factor, and comprehensive thermal hydraulic performance index as the objective functions. Ling et al [31] investigated the flow characteristics of non-Newtonian nanofluids flow in shell side of helical baffled heat transfer combined with elliptic tubes. They pointed out that a remarkable heat transfer enhancement can be obtained.…”