HEAT TRANSFER OF FLAT-OVAL TUBE BUNDLES IN CROSS FLOW

Authors

DOI:

https://doi.org/10.20535/1813-5420.2.2019.190010

Keywords:

heat transfer, investigations, flat-oval tube, staggered bundle, calculation, generalized correlations

Abstract

The goal of this work was to create generalized relationships for calculating the convective heat transfer coefficients of staggered bundles of flat oval tubes based on the obtained experimental data for recuperative heat exchangers of the “gas-gas” type in a wide range of changes in the geometric characteristics of tubes, bundles and flow regime parameters. An analysis of the known literature data by the authors shows that no systematic studies of the influence of geometric and step characteristics of tubes on heat transfer and aerodynamic drag of flat-oval tube bundles during transverse air flow in a wide range of Reynolds numbers were carried out. The results of numerical modeling are not experimentally confirmed. The published works contain fragmentary data, which are usually of carried a private character. Presented experimental studies of convective heat transfer of staggered bundles of flat oval tubes with transverse air flow around them were carried out in the range of Reynolds numbers 2000 < Red1 <30000 with a variation in the relative elongation of the profile of the flat oval tube d2 / d1 from 2 to 5, and the ratio of the transverse tube pitch to the longitudinal S1 / S2 ranged from 0,4 to 1,45. The influence of geometric and operational parameters on the heat transfer of bundles is established. The heat transfer rate of staggered bundles of flat-oval tubes when varying the elongation of the tubes profile d2 / d1 in the range from 2 to 5 changes by (10-25) %, and when varying the step characteristics of the tubes at d2 / d1 = const by (8-12) %. Evaluation of the accuracy of the generalizing formulas, which was carried out on the basis of an array of experimental data for the 49 studied bundles, indicates that the difference between the experimental and calculated values of the Nusselt numbers does not exceed ± 10%. Design relationships are proposed for determining the heat transfer coefficients of staggered bundles of flat-oval tubes, taking into account the influence of the operating parameters on the heat transfer, the geometric characteristics of flat-oval tubes and bundles and can be used in calculating the heat transfer of air heaters of boiler units, gas turbine plant regenerators.

References

Antuf’ev, V. M., Beletskyi, G. S. (1948). Heat transfer and aerodynamic drags of tube surfaces in crossflow. Moskow, USSR: Mashgiz, 119.

Kase, W. M., London, A. L. (1967). Compact heat exchangers. Moskow, USSR: Energy, 224.

Antuf’ev, V. M. (1966). Efficiency of different forms of heating convective surfaces. Moskow, USSR: Energy, 184.

Ala Ali Hasan. (2004). Thermal-hydraulic perfomance of oval tubes in a cross-flow of air. Heat and Mass Transfer, accepted for publication. ТHP 2004 by author and ТHP 2004 Springer-Verlag. By permission, 1-32.

Rudenko, A., Terekh, A., Tuz, V., Rogachov, V., Kondratyuk, V. (2015). Estimation of thermal aerodynamic efficiency of single tubes with different cross-section. Scientific Journal „ScienceRise”, No 2/2 (7), 7-11. DOI: 10.15587/2313-8416.2015.37446.

Benarji, N., Balaji, C., Venkateshan, S. P. (2008). Unsteady fluid flow and heat transfer over a bank of flat tubes. Heat Mass Transfer, 44, 445-461. DOI: 10.1007/s00231-007-0256-5.

Amer Jameel Shareef, Abdulmajeed A. Ramadhan. (2011). Heat Transfer and Fluid Flow Characteristic in banks Flat Tubes. Tikrit Journal of Engineering. Sciences, Vol. 18, (4), 88-103.

Ishak, M., Tahseen, Tahseen A., Rahman, Md. Mustafizur. (2013). Experimental investigation on heat transfer and pressure drop characteristics of air flow over a staggered flat tube bank in crossflow. International Journal of Automotive and Mechanical Engineering, V. 7, 900-911. DOI: http://dx.doi.org/10.15282/ijame.7.2012.7.0073.

Zhukauskas, A. (1982). A convective transfer in heat exchagers. Moscow, USSR: Science, 472.

Tahseen, Tahseen Ahmad, Rahman, M. M., Ishak, M. (2014). An experimental study of air flow and heat transfer over in–line flat tube bank. International Journal of Automotive and Mechanical Engineering, V. 9, 1487-1500. DOI: http://dx.doi.org/10.15282/ijame.9.2014.1.0123.

Kondratyuk, V. A., Terekh, A. M., Baranyuk, A. V., Pis’mennyi, E. N. (2015). Heat transfer of staggered bundles of flat oval tube in transversal flow. Eastern-European Journal of Enterprise Technologies, 1/8 (73), 43-48. DOI: 10.15587/1729-4061.2015.37318.

Pis’menyi, E.N., Kondratyuk, V.A., Zhukova, Y.V., Terekh, A. M. (2011). Heat transfer of staggered bundles of flat-oval tubes in cross flow. Eastern-European Journal of Enterprise Technologies, 2/8 (50), 4-8.

Thermal calculation of boiler plants (standard method) (1973). Ed. 2, edited by N. V. Kuznetsov. Moskow, USSR: Energy, 296.

Terekh, A. M., Semenyako, A.V., Tuz, V. E., Kondratyuk, V. A. (2013). Flowing around single cylinders in transversal flow. Eastern-European Journal of Enterprise Technologies, 2/8 (62), 23-26.

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Published

2019-12-27

Issue

No. 2 (2019): 56

Section

ENERGY EFFICIENCY AND ENERGY SAVINGS

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