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Research Papers

Experimental and Numerical Investigation of the Gas Side Heat Transfer and Pressure Drop of Finned Tubes—Part I: Experimental Analysis

[+] Author and Article Information
Rene Hofmann

Josef Bertsch GmbH & Co. KG,
Herrengasse 23,
A-6700 Bludenz, Austria
e-mail: rene.hofmann@bertsch.at

Heimo Walter

Mem. ASME
Institute for Energy Systems and Thermodynamics,
Vienna University of Technology,
Getreidemarkt 9, A-1060 Vienna, Austria
e-mail: heimo.walter@tuwien.ac.at

In Ref. [8], two different correlations are presented. The difference in the correlations is given in the coefficients C1, C3, and C5.

Manuscript received February 27, 2012; final manuscript received June 16, 2012; published online October 17, 2012. Assoc. Editor: Larry Swanson.

J. Thermal Sci. Eng. Appl 4(4), 041007 (Oct 17, 2012) (11 pages) doi:10.1115/1.4007124 History: Received February 27, 2012; Revised June 16, 2012

In this study, a heat transfer and pressure drop correlation are determined for helically I- and U-shaped finned tubes as well as for solid I-finned tubes at constant transverse and longitudinal spacing. In the heat transfer correlation, the influence of the number of tube rows arranged in flow direction is taken into consideration. A detailed description of the test rig and the data reduction procedure is presented. A thorough uncertainty analysis was performed to validate the results. The investigation has shown that the influence of the fin geometry on the heat transfer of the helically segmented I- and U-shaped tubes can be disregarded. The heat transfer correlation, which is valid for the helically segmented I- and U-shaped tubes in a staggered arrangement, can describe 90% of all measurement data within ±15%. All measurements are performed for constant transverse and longitudinal spacing. For the pressure drop coefficient, two new correlations, which are only valid for helically segmented U shaped finned tubes in a staggered arrangement, show an average deviation of approximately ±13% for 90% of all measurement results. All new correlations are compared with correlations from open and established literature for industrial boiler applications. The new heat transfer and pressure drop correlations show a relative deviation of ±20% in comparison with correlations in open literature. The new pressure drop correlations show the same characteristic as most correlations in the open literature.

Copyright © 2012 by ASME
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References

Figures

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Fig. 6

Airflow measurement uncertainties

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Fig. 5

Measurement range of the water mass flow

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Fig. 4

Position for thermocouples and pressure transducer positioning at test rig

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Fig. 3

Sketch of the measurement setup

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Fig. 2

Dimension of the test section and tube arrangement

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Fig. 1

Sketch of the test facility; the dimensions of the test rig are in millimeters

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Fig. 8

Contact area between fin and bare tube for I-, L- and U-shaped finned tubes

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Fig. 9

Row correction factor for different Re numbers for U-shaped segmented finned tubes

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Fig. 10

Comparison between the row correction factor Eq. (22) and correlations in the open literature

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Fig. 7

Sketch of the analyzed U-shaped segmented finned tube

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Fig. 11

Comparison between the heat transfer and the correlation of ESCOATM [8]; for eight tube rows (Pr = 0.71 and da = 38 mm)

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Fig. 13

Comparison between heat transfer correlation (26) and correlations in the open literature; based on geometrical data of helically U-shaped finned tube

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Fig. 12

Comparison between the heat transfer correlation (26) and our experimental data for segmented I- and U-shaped finned tubes

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Fig. 14

Pressure drop coefficient for different finned tube geometries, evaluated for 1 tube row

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Fig. 15

Regression of pressure drop coefficient at eight segmented finned tube rows

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Fig. 16

Comparison between the new correlation for the pressure drop, Eq. (28) and the experimental data

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Fig. 17

Comparison between the pressure drop correlation (28) and the correlations in the open literature

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