HEAT TRANSFER AND RESISTANCE OF STAGGERED BANKS OF AIR-COOLED HEAT EXCHANGERS FORMED FROM TUBES WITH ROLLED ALUMINUM FINS OF VARIOUS HEIGHT

摘要

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 airflow passing across the finned tubes. The fins are wiled 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, and3.57 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.