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

Abstract

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.

Numerical study of a round tube heat exchanger with louvered fins and delta winglets

“…On the other side of the fin (without winglets) an upwash region (indicated by ③) exists which yields a decrease in heat transfer. Joardar and Jacobi [3] explained that the heat transfer enhancement in the downwash region is greater than the reduction in the upwash region. Hence, a net heat transfer enhancement results.…”

“…Figure 2. (a) Delta winglet pair on a flat plate generating longitudinal vortices [3]; (b) Common-flowdown orientation of DWs on the fin of a round tube heat exchanger [4].…”

“…An appropriate DW placement and orientation in fin-and-tube heat exchangers reduces the poor heat transfer region in the tube wakes. To this purpose, the common-flow-down configuration of Figure 2b is frequently used [3]. Figure 2.…”

Convective Heat Transfer Enhancement and Entropy Generation of Laminar Flow of Water through a Wavy Channel

“…Vortex Generators have been intensively investigated recently [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Jacobi et al [22][23][24][25][26][27][28] studied on wavy finned tube with different configurations of delta wing vortex generators. From the literature review shows that in overall most of the research work focused on simple wave ratio.…”

Numerical Study of Fin-Tube Type Heat Exchanger With Delta Winglets

“…The goodness factor, jf-factor, increased with the increase of the Reynolds number and that the maximum value is 0.87.This experiment highlights the advantage of delta-winglet vortex generator and the overall performance improvement of the heat exchanger. Joardar and Jacobi (2007), also numerically investigated the flow and heat transfer enhancement using an array of VGs in a fin-and-tube exchanger with common-flow-up arrangement. They observed that the impingement of winglet redirected flow on the downstream tube is an important heat transfer augmentation mechanism for the inline-tube geometry.…”