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Cited by 281Heat Transfer and OptimizationHeat Transfer MechanismsHeat transfer and supercritical fluids

Air-side thermal hydraulic performance of multi-louvered fin aluminum heat exchangers

Kim, Man-Hoe, Bullard, Clark W.·2002·International Journal of Refrigeration
DOI 10.1016/s0140-7007(01)00025-1
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Written from the paper’s full text.

TL;DR

This experimental study measured air-side heat transfer and pressure drop for 45 multi-louvered fin and flat-tube aluminum heat exchangers over louver angles of 15–29°, fin pitches of 1.0/1.2/1.4 mm, flow depths of 16/20/24 mm, and air-side Reynolds numbers based on louver pitch of 100–600. General Colburn j and Fanning friction f correlations were developed with rms errors of ±14.5% and ±7%, respectively.

Key findings

  • Heat transfer coefficients decrease with flow depth and increase with face air velocity; pressure drops increase with flow depth and air velocity. For 24 mm flow depth, heat transfer coefficients increase with louver angle up to a maximum at 27° and then decrease; for 16 mm flow depth they do not change much with louver angle.
  • Friction factors increase with louver angle, but the effect decreases for louver angles larger than 21°. For louver angles below 19°, heat transfer coefficients decrease with fin pitch; for louver angles larger than 23°, they increase with fin pitch. The effect of fin spacing on heat transfer is relatively small (2–15%) and depends on flow depth and Reynolds number.
  • The j factors for 16 and 20 mm flow depths are similar, while those for 24 mm are smaller; the f factors for 20 and 24 mm flow depths are similar, while those for 16 mm are relatively smaller. The paper attributes this partly to different tube geometry (2 mm for 20 and 24 mm flow depths and 3 mm for 16 mm).
  • The j correlation predicts 225 test data points within an rms error of ±14.5%, and the f correlation within ±7%. The f correlation indicates that flow depth is an important parameter for pressure drop; the present and Sunden and Svantesson correlations reflect flow-depth effects, while other compared correlations do not.

Methods

  • Tests used a suction-type wind tunnel in a constant-temperature and humidity chamber with 45 multi-louvered fin and flat-tube heat exchangers. Louver pitch, louver length, and fin height were 1.7, 6.4, and 8.15 mm; tested core size was 350×255 mm; tube pitches were 11.15 and 10.15 mm.
  • Test conditions were air-side Reynolds numbers based on louver pitch and maximum velocity of 100–600, a constant tube-side water flow rate of 0.32 m³/h, and inlet air and water temperatures of 21°C and 45°C. Data were reduced using the effectiveness-NTU method for cross-flow with both fluids unmixed, and results were expressed as Colburn j and Fanning friction f factors versus Reynolds number based on louver pitch.
  • Measurement uncertainties were less than ±3% for heat transfer rate, ±12% for heat transfer coefficients, and ±10% for pressure drops.

Limitations

  • The paper states no dedicated limitations section. Stated constraints include that the j and f correlations were developed from 225 test data points for Fp/Lp < 1, with rms errors of ±14.5% and ±7%, and that tests covered only air-side Reynolds numbers of 100–600, a water flow rate of 0.32 m³/h, and inlet air/water temperatures of 21°C/45°C.
  • Evident from the text: the 45 samples cover limited geometry ranges (louver angles 15–29°, fin pitches 1.0–1.4 mm, flow depths 16–24 mm), so extrapolation beyond these configurations and test conditions is not supported. Comparisons with other correlations use only two sample heat exchangers (type I and type II), and some explanations for differences among correlations are described as difficult to explain.
  • The published record includes an erratum correcting Figs. 9 and 11 of the original paper.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/s0140-7007(01)00025-1

Cites

21 of 21 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 10 cited sources checked · 0 supported · 0 flagged

  • Findingown data
    § 3. Results and discussion · p. 7

    The effect of louver angle on the heat transfer coefficients depends on flow depth.

    “the effect of louver angle on the heat transfer coefficients depends on flow depth”
    Quote in the paperSubstantial claim
  • Findingown data
    § 3. Results and discussion · p. 8

    For a 20 mm flow depth, the effect of louver angle on heat transfer and pressure drop varies with face velocity, decreasing with face air velocity due to more mixing at larger face velocities.

    “For 20 mm flow depth, the effect of louver angle on the heat transfer and pressure drop varies with face velocity. It decreases with face air velocity due to more mixing for larger face velocities.”
    Quote in the paperSubstantial claim
  • Findingown data
    § 3. Results and discussion · p. 7

    Pressure drops for all tested flow depths increase with louver angle.

    “Pressure drops for all flow depths increase with louver angle”
    • Also stated in: § 4. Concluding remarks · p. 10 · plain
      “Pressure drops increase with louver angle and flow depth and decrease with increasing fin pitch.”
    Quote in the paperSubstantial claim
  • Findingown data
    § 3. Results and discussion · p. 7

    For a 16 mm flow depth, heat transfer coefficients do not change much with louver angle.

    “For 16 mm flow depth, heat transfer coefficients do not change much with louver angle.”
    Quote in the paperNot a substantial claim
  • Findingown data
    § 3. Results and discussion · p. 8

    The heat transfer behaviors with fin pitch observed here are different compared to conventional finned tube heat exchangers.

    “These heat transfer behaviors with fin pitch are different, compared to the conventional finned tube heat exchangers.”
    Quote in the paperSubstantial claim
  • May combine two claims. 16
  • Classified as probably not a substantial claim. 4
  • The quote only partly states this claim. 1

  • May combine two claims.

    Findingown data
    § 3. Results and discussion · p. 8

    Friction factors increase with louver angle, but the effect of louver angle on the f factor decreases for louver angles larger than 21 degrees.

    “Friction factors increase with louver angle, but the effect of louver angle on the f factor decreases for louver angles larger than 21”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3. Results and discussion · p. 7

    For a 24 mm flow depth, heat transfer coefficients increase with louver angle, reach a maximum at 27 degrees, and then decrease with louver angle.

    “for 24 mm flow depth, heat transfer coefficients increase with louver angle, have a maximum at 27 , and again decrease with louver angle”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given
    § 3. Results and discussion · p. 7

    For the tested heat exchangers, the air-side pressure drops increase with flow depth and air velocity.

    “the pressure drops increase with flow depth and air velocity”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning
    § 3. Results and discussion · p. 7

    For the tested multi-louvered fin heat exchangers, the air-side heat transfer coefficients decrease with flow depth and increase with face air velocity.

    “the heat transfer coefficients decrease with flow depth and increase with face velocity”
    • Also stated in: § 4. Concluding remarks · p. 10 · plain
      “Heat transfer coefficients decrease with flow depth and increase exponentially with face air velocity.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3. Results and discussion · p. 8

    The j factor increases with louver angle, but the effect of louver angle on the j factor varies with flow depth.

    “The j factor increases with louver angle, but its effect on the j factor varies with flow depth.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3. Results and discussion · p. 8

    The j factors for flow depths of 16 and 20 mm are similar, while those for a 24 mm flow depth are smaller.

    “the j factors for F d=16 and 20 mm are similar and for F d=24 mm are smaller”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 4. Concluding remarks · p. 10

    The effect of louver angle on heat transfer is different according to flow depth, fin spacing and Reynolds number, but the effect of fin spacing is relatively small.

    “The effect of louver angle on heat transfer is different according to flow depth, fin spacing and Reynolds number, but the effect of fin spacing is relatively small.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3. Results and discussion · p. 8

    For a 24 mm flow depth, the j factor increases with louver angle for louver angles up to 27 degrees and decreases with louver angle for louver angles greater than 27 degrees.

    “for F d=24 mm, j factor increases with louver angle for L a 4 27 , and decreases with louver angle for L a &gt;27”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3. Results and discussion · p. 8

    The effect of fin spacing on the heat transfer is relatively small (2-15%) and depends on flow depth and Reynolds number.

    “The effect of fin spacing on the heat transfer is relatively small (2-15%) and depends on flow depth and Reynolds number.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 3. Results and discussion · p. 8

    The f factors for flow depths of 20 and 24 mm are similar, while those for a 16 mm flow depth are relatively smaller than those of larger flow depth.

    “the f factors for F d=20 and 24 mm are similar and for F d=16 mm are relatively smaller than those of larger flow depth”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning
    § 3.1. Heat transfer correlation · p. 9

    The present, Sunden and Svantesson's, and Chang and Wang's j-factor correlations reflect the effect of different flow depths, while the other correlations give similar j factors for both heat exchangers because flow depth is not included in them.

    “The present, Sunden and Svantesson's [13] and Chang and Wang's correlations [16] reflect the effect of different flow depths, while the other correlations have the similar j factors for both heat exchangers since the flow depth is not included in their correlations.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [13] Sunden B, Svantesson J. Correlation of j- and f-factors for multilouvered heat transfer surfaces. In: Proceedings of the 3rd UK National Conference on Heat Transfer, 1992. pp. 805-11.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [16] Chang, 1997, A generalized heat transfer correlation for louvered fin geometry, Int. J. Heat Transfer source

  • May combine two claims.

    Findingnone given
    § 3.2. Pressure drop correlation · p. 10

    The present and Sunden and Svantesson's f-factor correlations reflect the effect of flow depth on the pressure drop, while other correlations do not.

    “The present and Sunden and Svantesson's [13] correlations reflect the effect of flow depth on the pressure drop, while other correlations do not reflect.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [13] Sunden B, Svantesson J. Correlation of j- and f-factors for multilouvered heat transfer surfaces. In: Proceedings of the 3rd UK National Conference on Heat Transfer, 1992. pp. 805-11.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisenone given
    § 1. Introduction · p. 2

    The air-side thermal-hydraulic performance of multi-louvered fin and flat tube heat exchangers depends on louver geometry such as fin and louver pitches, louver angle, and flow depth.

    “The air-side thermal-hydraulic performance of multilouvered fin and flat tube heat exchangers depends on louver geometry such as fin and louver pitches, louver angle, and flow depth.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Study design and conductnone given
    § 2.2. Test heat exchangers · p. 4

    All louver geometries were checked before brazing and the overall heat exchanger quality after brazing was excellent.

    “All louver geometries were checked before brazing and overall heat exchanger quality after brazing was excellent.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § 1. Introduction · p. 2

    A general f correlation for the pressure drop of louvered fin heat exchangers is not available in the open literature.

    “the general f correlation for the pressure drop is not available in the open literature.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § 3. Results and discussion · p. 8

    When Reynolds number and louver angle are small and the ratio of fin pitch to louver pitch is large, friction loss along the flow depth becomes less significant so the airflow becomes duct-directed, and this decrease of flow efficiency causes the heat transfer coefficient to decrease.

    “When Reynolds number and louver angle are small and the ratio of fin pitch to louver pitch is large, friction loss along the flow depth becomes less significant so the airflow becomes duct-directed. This decrease of flow efficiency causes the heat transfer coefficient to decrease.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data
    § 3.1. Heat transfer correlation · p. 9

    Davenport's correlation is more suitable for heat exchangers with larger flow depth and does not reflect the effect of flow depth.

    “indicating that Davenport's correlation [3] is more suitable for the heat exchangers with larger flow depth and does not reflect the effect of flow depth.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3] Davenport, 1983, Correlation for heat transfer and friction characteristics of louvered fin, AICHE Sym. Ser.

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation
    § 1. Introduction · p. 2

    A multi-louver fin and flat tube heat exchanger is one of the potential alternatives for replacing conventional finned tube heat exchangers.

    “A multi-louver fin and flat tube heat exchanger is one of the potential alternatives for replacing conventional finned tube heat exchangers [1].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Webb RL. Advances in air-cooled heat exchanger technology. In: Proceedings of the International Conference on Heat Exchangers for Sustainable Development, Lisbon, Portugal, 1998. p. 677–92.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims. The quote only partly states this claim.

    Study design and conductcitation
    § 2.4. Data reduction · p. 6

    Accounting for all instrument errors, property uncertainties, and geometric tolerances, the uncertainties for the heat transfer coefficients and pressure drops were 12 and 10%, respectively.

    “uncertainties for the heat transfer coefficients and pressure drops were 12 and 10%, respectively [24].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [24] Moffat, 1988, Describing the uncertainties in experimental results, Exp. Thermal and Fluid Sci. source
19 of 19

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • All correlations by Chang and co-workers and Kim and Bullard can only correlate less than 67% (as low as 36.56%) of the current experimental data with a deviation of ±25%.

    “As can be seen from the previously discussed four correlations, all the correlations by Chang and co-works and Kim and Bullard can only correlate less than 67% (as low as 36.56%) of the current experimental data with a deviation of ± 25%.”

    From A heat transfer and friction factor correlation for low air-side Reynolds number applications of compact heat exchangers (1535-RP) (2017) · cites this paper as Kim and Bullard (2002)

    Sections 3.1 (p. 9) and 3.2 (pp. 9–10) establish that Kim and Bullard developed heat-transfer and friction-factor correlations. They do not report that the correlations capture less than 67%, or as little as 36.56%, of the citing study’s experimental data within ±25%; those figures appear to be the citing authors’ own comparison. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • Kim and Bullard presented fluid-flow and heat transfer correlations for dry air using 40 configurations.

    “Also, Kim and Bullard [61] presented fluid-flow and heat transfer correlations for dry air using 40 configurations.”

    From Compact and microchannel heat exchangers: A comprehensive review of air-side friction factor and heat transfer correlations (2018) · cites this paper as [61]

    The heat-transfer correlation section (p. 9) says the j-factor correlation used 225 data points from 45 heat-exchanger configurations, not 40. The pressure-drop correlation section (p. 9) also reports an f-factor correlation. These sections establish air-side heat-transfer and flow-resistance correlations but do not explicitly describe the air as dry. (LLM, conf=0.92)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Type-I tube pitch differs between tables

    Minor

    Table 1 assigns a tube pitch of 11.15 mm to the 16 mm flow-depth exchangers, including the 1.4 mm fin-pitch, 23° louver-angle configuration. Table 2 gives the matching type-I configuration a tube pitch of 10.15 mm.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 8

  1. Webb RL. Advances in air-cooled heat exchanger technology. In: Proceedings of the International Conference on Heat Exchangers for Sustainable Development, Lisbon, Portugal, 1998. p. 677–92.
  2. Davenport CJ. Heat transfer and fluid flow in louvered triangular ducts. PhD thesis, Department of Mechanical Engineering, Lanchester Polytechnic, 1980.
  3. Davenport, 1983, Correlation for heat transfer and friction characteristics of louvered fin, AICHE Sym. Ser., 79, 19
  4. Achaichia A. The performance of louvered tube-and-plate fin heat transfer surface. PhD thesis, Department of Mechanical and Production Engineering, Brighton Polytechnic, 1987.
  5. Webb, 1992, Air-side performance of enhanced brazed aluminum heat exchangers, ASHRAE Trans., 98, 391
  6. Rugh, 1992, A study of a very compact heat exchanger used for passenger compartment heating in automobiles, ASME Symp. Ser. HTD-Vol. 201, 15-24
  7. Sunden B, Svantesson J. Correlation of j- and f-factors for multilouvered heat transfer surfaces. In: Proceedings of the 3rd UK National Conference on Heat Transfer, 1992. pp. 805-11.
  8. Rich, 1973, The effect of fin spacing of the heat transfer and friction performance of multi-row, smooth plate fin-and-tube heat exchangers, ASHRAE Trans., 79, 137

Cited by

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Related

Authors
Kim, M.-H., & Bullard, C. W.
Affiliations
University of Illinois Urbana-Champaign (US)
Corresponding author
Kim, Man-Hoe
ORCID
Kim, Man-Hoe
Venue
International Journal of Refrigeration
Publisher
Elsevier BV
Published
2002-05
Volume
25
Issue
3
Pages
390-400
ISSN
0140-7007 (ISSN-L)
DOI
10.1016/s0140-7007(01)00025-1
OpenAlex
W2066694433
Semantic Scholar
49cfbe56084c4f5d7d84db303ee3d9a6eff9b535
Cited by
280
References
21
Citations by year
2026: 12 · 2025: 21 · 2024: 14 · 2023: 17 · 2022: 15 · 2021: 14 · 2020: 17 · 2019: 14 · 2018: 17 · 2017: 26 · 2016: 21 · 2015: 20 · 2014: 3 · 2013: 6 · 2012: 12
FWCI
10.64
Type
journal article
Language
en
Open access
closed
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
International Journal of Refrigeration (publishedVersion)
Topics
  • Physical Sciences › Engineering › Mechanical Engineering › Heat Transfer and Optimization
  • Physical Sciences › Engineering › Mechanical Engineering › Heat Transfer Mechanisms
  • Physical Sciences › Engineering › Computational Mechanics › Heat transfer and supercritical fluids
Keywords
louvered fin heat exchanger, aluminum heat exchangers, air-side heat transfer, pressure drop, fin angle, fin spacing, flow depth, Colburn j-factor, Fanning friction factor, heat transfer coefficient, cross-flow heat exchanger, effectiveness-NTU method, flat tube heat exchanger, air-to-water heat exchanger

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