Numerical study on a slit fin-and-tube heat exchanger with longitudinal vortex generators

Over the last decades several studies have searched for improved Fin and Tube Heat Exchanger (FTHE) designs capable of providing the best thermo-hydraulic performance. The present study aims at quantifying and comparing the thermo-hydraulic performance of different FTHE configurations. Six different designs were analyzed. The first FTHE consisted of an in-line circular tube arrangement and the last one was a FTHE with staggered oval tube with two pairs of Delta Winglet Vortex Generators (DWVG) in common flow up–common flow down (CFU-CFD) configuration. The best performance was obtained using DWVG in CFU-CFD orientation. This configuration enabled a 90% increase of the thermal performance factor when compared with the first case, using only two pairs of vortex generator´s per tube.

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A Numerical Study of Flow and Heat Transfer Enhancement Using an Array of Delta-Winglet Vortex Generators in a Fin-and-Tube Heat Exchanger

Journal of Heat Transfer ◽

10.1115/1.2740308 ◽

2006 ◽

Vol 129 (9) ◽

pp. 1156-1167 ◽

Cited By ~ 62

Author(s):

A. Joardar ◽

A. M. Jacobi

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Heat Transfer Enhancement ◽

Numerical Study ◽

Flow Behavior ◽

Vortex Generators ◽

Computational Domain ◽

Transfer Enhancement ◽

Local Flow ◽

Tube Heat Exchanger

This work is aimed at assessing the potential of winglet-type vortex generator (VG) “arrays” for multirow inline-tube heat exchangers with an emphasis on providing fundamental understanding of the relation between local flow behavior and heat transfer enhancement mechanisms. Three different winglet configurations in common-flow-up arrangement are analyzed in the seven-row compact fin-and-tube heat exchanger: (a) single–VG pair; (b) a 3VG-inline array (alternating tube row); and (c) a 3VG-staggered array. The numerical study involves three-dimensional time-dependent modeling of unsteady laminar flow (330⩽Re⩽850) and conjugate heat transfer in the computational domain, which is set up to model the entire fin length in the air flow direction. It was found that the impingement of winglet redirected flow on the downstream tube is an important heat transfer augmentation mechanism for the common-flow-up arrangement of vortex generators in the inline-tube geometry. At Re=850 with a constant tube-wall temperature, the 3VG-inline-array configuration achieves enhancements up to 32% in total heat flux and 74% in j factor over the baseline case, with an associated pressure-drop increase of about 41%. The numerical results for the integral heat transfer quantities agree well with the available experimental measurements.

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Performance Analysis for Elliptical Tube Longitudinal Vortex Generators

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.383-390.6037 ◽

2011 ◽

Vol 383-390 ◽

pp. 6037-6041

Author(s):

Jun Jie Zhou ◽

Xue Hong Wu ◽

Xiao Qian Li ◽

Jin Yin Huang ◽

Ding Biao Wang

Keyword(s):

Reynolds Number ◽

Nusselt Number ◽

Heat Exchanger ◽

Friction Coefficient ◽

Vortex Generator ◽

Heat Transfer Process ◽

Vortex Generators ◽

Longitudinal Vortex ◽

Tube Heat Exchanger ◽

Comprehensive Performance

In this paper, three-dimensional numerical simulation is conducted on the flow and heat transfer process for elliptical tube heat exchanger with rectangular vortex generators and triangular vortex generator by Fluent software, respectively, and the performance for elliptical tube heat exchanger with plate fin is compared. The results show that the Nusselt number increases with the increase in Reynolds number for the inlet velocity range from 1 to 5m/s, friction coefficient decreases with the increase in Reynolds number; at the same Reynolds number, Nusselt number for fin with Vortex Generators and friction coefficient are higher than that of elliptical tube with plate fin ; the vortex generator shape and angle of attack have a great impact on the comprehensive performance within a simulated attack angle and the velocity, at the same pump power, the comprehensive performance for heat exchanger with the rectangular vortex generator increase up to 10%.

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