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Heat and Mass Transfer

, Volume 53, Issue 9, pp 2961–2973 | Cite as

The effect of shape of winglet vortex generator on the thermal–hydrodynamic performance of a circular tube bank fin heat exchanger

  • Wanling Hu
  • Liangbi WangEmail author
  • Yong Guan
  • Wenju Hu
Original

Abstract

In real application, the shape of the vortex generator has great influence on the heat transfer and flow resistance characteristics of tube bank fin heat exchanger. Therefore, the effect of the shape of the vortex generator on heat transfer performance of such heat exchanger should be considered. In this paper, the effect of three different shaped vortex generators (i.e. delta winglet, rectangular winglet and trapezoid winglet) on heat transfer intensity and secondary flow intensity of a circular tube bank fin heat exchanger was numerically studied. The results show that with increasing Re, overall average Nu and the non-dimensional secondary flow intensity Se m increase however friction factor f decreases. A corresponding relationship can be found between Nu and Se m, which indicates that the secondary flow intensity determines the heat transfer intensity in the fin-side channel of circular tube bank fin heat exchanger with different shaped vortex generators on the fin surfaces. Under the identical pumping power constrain, the optimal shape of the vortex generators is the delta winglet vortex generators for the studied cases.

Keywords

Heat Transfer Heat Exchanger Friction Factor Secondary Flow Heat Transfer Enhancement 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols

A

Cross section area of flow passage (m2)

A(x)

Cross section area at position x (m2)

cp

Specific heat capacity (J kg−1 K−1)

D

Diameter of the tube (m)

de

Characteristic length of flow channel (m)

f

Friction factor, f = Δpd e/(L x ρu max 2 /2)

H

Height of winglet type vortex generator (m)

Lx

Stream wise length of fin (m)

n

Direction normal to the cross section or wall surface

N2

Number of the tubes

Nu

Nusselt number, Nu = hd e/λ

p

Pressure (Pa)

Re

Reynolds number, Re = ρu max d e/μ

S1

Transversal pitch between the tubes (m)

S2

Longitudinal pitch between the tubes (m)

Se

Secondary flow intensity, Se = ρd e U s/μ

S(x)

Span strip of fin and tube area at position x (m2)

Tp

Net fin spacing (m)

T

Temperature (K)

umax

Maximum average velocity of air (m s−1)

ui, u, v, w

Components of velocity vector (m s−1)

X,Y, Z

Coordinates

Greek letters

λ

Thermal conductivity (W m−1 K−1)

μ

Viscosity (kg m−1 s−1)

ρ

Density (kg m−3)

θ

Attack angle of vortex generator (°)

Δ

Difference between two values

Δp

Pressure drop (Pa)

ω

Vorticity (s−1)

ξ,η, ζ

Body fitted coordinate axes

Subscripts

ave

Average value

bulk

Cross section averaged value

in

Inlet parameters

local

Local value

m

Mean or average value

out

Outlet parameters

s

Span-averaged

w

Wall or fin surface

Notes

Acknowledgement

This work is supported by the National Natural Science Foundation of China (No. 51306085 and 51468028), the Science and Technology Plan of Gansu Province (No. 1506RJZA065 and 1506RJZA066), and Beijing Key Lab of Heating, Gas Supply, Ventilating and Air Conditioning Engineering (No. NR2015K05).

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Copyright information

© Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  • Wanling Hu
    • 1
    • 2
  • Liangbi Wang
    • 2
    • 3
    Email author
  • Yong Guan
    • 1
  • Wenju Hu
    • 4
  1. 1.School of Environmental and Municipal EngineeringLanzhou Jiaotong UniversityLanzhouPeople’s Republic of China
  2. 2.Key Laboratory of Railway Vehicle Thermal Engineering (Lanzhou Jiaotong University)Ministry of Education of ChinaLanzhouPeople’s Republic of China
  3. 3.Department of Mechanical EngineeringLanzhou Jiaotong UniversityLanzhouPeople’s Republic of China
  4. 4.Beijing Key Lab of Heating, Gas Supply Ventilating and Air Conditioning EngineeringBeijing University of Civil Engineering and ArchitectureBeijingPeople’s Republic of China

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