ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Inserts Intensifying Heat Transfer Inside the Tubes: Design, Investigation, and Performance Efficiency Criteria

W. Krajewski and A. Ko Lodziej

Institute of Chemical Engineering of the Polish Academy of Sciences, PL-44-100 Gliwice

E-mail: ask@iich.gliwice.pl

Received: 28 March 2003

Abstract: The use of tube inserts for enhancing heat transfer during air flow was investigated in regard to their adverse e ect of the increase of pressure drop. The pressure drop and heat transfer characteristics of nine designed metal inserts were measured and correlated in terms of Fanning friction factor, Colburn factor, and Nusselt number vs. Reynolds number. The selection of an optimal insert was difficult since the variations of f—j—Nu charts did not provide unequivocal information. The flow, heat, and heat-flow efficiencies were formulated in order to select the best carrier for two general cases: the constant flow (V-case) and constant pumping power (N-case). A one-dimensional criterion (ε_hf vs. Re) and a three-dimensional one (ε_hf vs. ε_h and ε_f) as well as unavoidable thermal and flow limitations of the process were discussed.

Chemical Papers 57 (6) 397–402 (2003)