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Journal of Enhanced Heat Transfer

Theory and Application in High Performance Heat and Mass Transfer

ISSN for PRINT: 1065-5131

Institutional price:	$577.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2006, Volume13

103 pages

DOI: 10.1615/JEnhHeatTransf.v13.i2

Issue price - $148.00

Performance Characteristics of Some "Rough Surfaces" with Tube Inserts for Single-Phase Flow

Ventsislav D. Zimparov
Gabrovo Technical University, 4, H. Dimitar Str., 5300 Gabrovo, Bulgaria

Plamen J. Penchev
Gabrovo Technical University, 4, H. Dimitar Str., 5300 Gabrovo, Bulgaria

Dr. 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

ABSTRACT

One of the most promising heat transfer enhancement techniques is the compound enhancement method, in which different enhancement techniques are used simultaneously. This study compares the characteristics of some passive combined techniques for single-phase flow studied up to now: rough tube (sand-grain roughness), internally grooved rough tube, three-dimensional internal extended surface, and corrugated tube — all of them combined with twisted-tape inserts. An internally grooved tube with wire coil inserts is also considered. The performance characteristics of these combinations of "rough" surfaces with tube inserts have been assessed using traditional performance evaluation criteria extended by entropy generation. The goal is to evaluate the influence of the characteristic parameters of the tubes: protuberance-height-to-diameter ratio e/D_i, relative pitch p/e, relative helix angle (β_*, and others, and the relative pitch of the twisted tape or wire coil H/D_i on the thermodynamic efficiency. The benefits of replacing the smooth tubes in shell-and-tube heat exchangers were evaluated for different practical applications. The optimal thermodynamic performance can be defined by minimization of the enhancement entropy generation number compared with the relative increase of the heat transfer rate or relative reduction of the heat transfer area.