Heat transfer and resistance of staggered banks of air-cooled heat exchangers formed from tubes with rolled aluminum fins of various height

Abstract

Results are presented for experimental investigation of reduced heat transfer and aerodynamic resistance of five staggered six-row banks of bimetallic finned tubes in heat exchange sections of air coolers with a forced air flow passing across the finned tubes. The fins are rolled onto circular steel tubes with a diameter d 0 = 25 mm. The relative transverse spacing of the tubes in the lattices of banks is s 1 = S 1 /d = 1.136, and the longitudinal spacing s 2 = S 2 /d = 0.905, where d is the outside diameter of the spiral fin. The banks were assembled from tubes with a fin height h = 15.23, 11.57, 9.07, 5.56, and 3.57 m. The diameter of the fin along the base was constant d 0 = 25.87 mm. The quantitative effect of the relative height h/d 0 on the average heat transfer and resistance of a bank is determined. The experimental data are described by criterial equations of the form Nu = f(Re) and Eu = f(Re) in the interval of Reynolds numbers Re = 3000–30000.