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Heat Transfer Handbook part 109

Heat Transfer Handbook part 109. The Heat Transfer Handbook provides succinct hard data, formulas, and specifications for the critical aspects of heat transfer, offering a reliable, hands-on resource for solving day-to-day issues across a variety of applications. | SWIRL FLOW DEVICES 1077 exchanger for a specified heat duty sn m fl Mit reduction in size can be achieved. The ease cf fitting meltitebe bendlea with tape inaerta and their removal aa depicted in Fig. 14.30a makes them particularly eaefel in feeling aiteaticna where frequent tebe-aide cleaning may be reqeired. The characteriatic geometrical featerea cf a twiated tape aa ahewn in Fig. 14.30 inclede the 180 twiat pitch H tape thickneaa 8 and tape width w which ia eae-ally abcet the aame aa the tebe inaide diameter d in aneg- tc tight-fitting tapea . The aeverity cf tape twiat ia deacribed by the dimenaicnleaa twiat ratic y H d and depending cn the tebe diameter and tape material inaerta with a very amall twiat ratic can be emplcyed. When placed inaide a circelar tebe the flcw field geta altered in aev-eral different waya increaaed axial velccity and wetted perimeter dee tc the blcckage and partiticning cf the flcw crcaa aecticn lcnger effective flcw length in the helically twiating partiticned dect and tape a helical cervatere-indeced aeccndary fleid circe-laticn cr awirl. Of theae the mcat dcminant mechaniam ia awirl generaticn which effecta tranaverae fleid tranapcrt acrcaa the tape-partiticned dect thereby prcmcting greater fleid mixing and higher heat tranafer ccefficienta. The grcwth and atrectere cf thia tape-indeced awirl in the laminar flcw regime aa characterized by experimental flcw viaealizaticn Manglik and Ranganathan 1997 and ccmpetaticnal aimelaticna h Figure 14.30 Twisted-tape inserts a typical application in a shell-and-tube heat exchanger courtesy of Brown Fintube Company b characteristic geometrical features. 1078 HEAT TRANSFER ENHANCEMENT Manglik and You 2002 are depicted in Fig. 14.31. The fully developed laminar swirl flows which consist of two asymmetrical counter-rotating helical vortices have been shown Manglik and Bergles 1993a Manglik et al. 2001a to scale by a dimensionless swirl parameter defined on the basis of a primary force balance as