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Journal of Enhanced Heat Transfer

Impact factor: 0.562

ISSN Print: 1065-5131
ISSN Online: 1563-5074

Journal of Enhanced Heat Transfer

DOI: 10.1615/JEnhHeatTransf.2011002711
pages 1-11


Ventsislav D. Zimparov
Gabrovo Technical University, 4 Hadji Dimitar Strasse, 5300 Gabrovo, Bulgaria
Valentin Metodiev Petkov
Gabrovo Technical University, 4, Hadji Dimitar, Str. 5300 Gabrovo, Bulgaria
Arthur E. Bergles
Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York; University of Maryland, College Park, Maryland; Massachusetts Institute of Technology, Cambridge, Massachusetts, USA


Recent investigation of the performance characteristics of some passive compound heat transfer enhancement techniques revealed that the combination of corrugated tubes with twisted-tape inserts seems to be a very attractive enhancement technique for single-phase turbulent flow. This holds in the range of height-to-diameter ratios e/Di > 0.04 and small relative pitches of the twisted tape, H/Di. This paper presents the latest results of an experimental investigation of the friction factors and heat transfer coefficients (inside with water as working fluid and outside with condensing steam) of eight single-start, spirally corrugated tubes with geometrical parameters: 0.053 < e/Di < 0.089 and ridge pitch-to-height ratio 6.8 < p/e < 11.0 combined with twisted tapes with H/Di = 4.7, 5.7, and 7.6, in the range of Reynolds number, 3.5 × 103 < Re < 5.0 × 104. The increase of outside heat transfer coefficient E0 is presented as a function of geometrical parameters of the depth of the corrugated tube through the Weber number, We, and the relative pitch of the twisted tape H/Di. The effect of Reynolds number on E0 is discussed.