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Research Papers: Heat Exchangers

Louver Finned Heat Exchangers for Automotive Sector: Numerical Simulations of Heat Transfer and Flow Resistance Coping With Industrial Constraints

[+] Author and Article Information
M. Ferrero

e-mail: ferrma@gmail.com

A. Scattina

e-mail: alessandro.scattina@polito.it
Department of Mechanical and Aerospace
Engineering,
Politecnico di Torino,
Turin 10129, Italy

E. Chiavazzo

Energy Department,
Politecnico di Torino,
Turin 10129, Italy
e-mail: eliodoro.chiavazzo@polito.it

F. Carena

e-mail: Franca.Carena@denso-ts.it

D. Perocchio

e-mail: Davide.Perocchio@denso-ts.it

M. Roberti

e-mail: Marta.Roberti@denso-ts.it

G. Toscano Rivalta

e-mail: Giovanni.Toscano@denso-ts.it
DENSO Thermal Systems,
Poirino 10046, Italy

P. Asinari

Energy Department,
Politecnico di Torino,
Turin 10129, Italy
e-mail: pietro.asinari@polito.it

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received July 20, 2012; final manuscript received May 21, 2013; published online September 27, 2013. Assoc. Editor: William P. Klinzing.

J. Heat Transfer 135(12), 121801 (Sep 27, 2013) (12 pages) Paper No: HT-12-1388; doi: 10.1115/1.4024758 History: Received July 20, 2012; Revised May 21, 2013

Louvered fins perform better than any other geometry in accomplishing the task of enhancing heat transfer of compact heat exchangers without prohibitive costs and pressure drops. For this reason, they are widely adopted for automotive applications. However, in order to improve louvered-fin compact heat exchangers, it is strongly required to understand how louvered fins behave regarding both heat transfer and pressure drop taking into account industrial constraints. For this purpose, numerical simulations based on the equations of thermofluid dynamics have been developed for this study. In particular, boundary heat flux and pressure distributions have been analyzed along the louvered-fin assembly and around the louvers, and even the effects of the flat portions (central and lateral louvers) have been investigated. In particular, the effects of the main geometrical parameters, such as fin pitch, louver pitch, and louver angle, have been evaluated by performing simulations on 40 different configurations. The results show that there is not one optimum configuration for the heat exchangers. Finally, a detailed procedure for the optimization of louvered-fin compact heat exchangers, considering industrial constraints is suggested according to multiple regression technique of the numerical results.

Copyright © 2013 by ASME
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References

Figures

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Fig. 4

Temperature distribution (on the left) and pressure distribution (on the right) for the model with three airway pitches (Fp = 100%, Lp = 100%, θ = 29 deg)

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Fig. 5

Turbulent kinetic energy for the Fp = 100%, Lp = 100%, θ = 31 deg model

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Fig. 6

Turbulent viscosity ratio for the Fp = 100%, Lp = 100%, θ = 31 deg model

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Fig. 7

Wall y+ values for the Fp = 100%, Lp = 100%, θ = 31 deg model

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Fig. 8

Convergence of the solution in function of mesh elements number and mesh base size for Fp = 100%, Lp = 100%, θ = 31 deg (circles), and Fp = 100%, Lp = 200%, θ = 31 deg (diamonds)

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Fig. 9

Flow path inside the louver array

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Fig. 10

Temperature trend along a complete air path (Fp = 100%, Lp = 100%, θ = 31 deg) (1 and 2 are the beginning and ending points of the louvered fin in the lower row, 3 and 4 are the beginning and ending points of the louvered fin in the upper row)

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Fig. 11

Temperature and pressure profile along the first half of the louver array (Fp = 100%, Lp = 100%, θ = 31 deg)

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Fig. 13

Sensitivity to Fp (Lp = 100% θ = 31 deg)

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Fig. 12

On the left pressure drop as a function of the louver angle for two different fin pitches, on the right heat transfer as a function of the louver angle for two different fin pitches

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Fig. 17

Heat transfer as a function of the louver angle for two different louver pitches (Fp = 100% on the left, Fp = 108.33% on the right)

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Fig. 2

Computational domain (front view in the upper part and detailed top view in the lower part)

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Fig. 1

Details of louvered fin

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Fig. 14

Air temperature saturation for different louver pitches (Fp = 100%, Lp = 100%, θ = 31 deg on the left part, Fp = 100%, Lp = 200%, θ = 31 deg on the right part); temperatures of both louver rows are reported separately (almost overlapping)

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Fig. 15

Sensitivity to Lp (Fp = 100%, θ = 31 deg). At Lp = 100%, we witness an optimal condition.

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Fig. 16

Pressure drop as a function of the louver angle for two different louver pitches (Fp = 100% on the left, Fp = 108.33% on the right)

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Fig. 19

Temperature and pressure profile downstream the flat portions (Lp = 100%, Fp = 100%, θ = 31 deg)

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Fig. 21

Percentage contributions after pooling. On the left and right part, we report results on heat transfer and pressure losses, respectively.

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Fig. 25

Regression line of pressure loss in function of louver angle for each of the configurations tested

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Fig. 22

Percentage reduction in heat transfer (dashed line), pressure loss (full line), and combined effect respect to the base configuration for layouts with Fp = 100%

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Fig. 23

Percentage reduction in heat transfer (dashed line), pressure loss (full line), and combined effect respect to the base configuration for layouts with Fp = 108.33%

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Fig. 24

Percentage reduction in heat transfer (dashed line), pressure loss (full line), and combined effect respect to the base configuration for both the fin pitches

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Fig. 18

Air velocity vectors for high and low values of louver angle (Fp = 100%, Lp = 100%)

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