Сравнение различных способов интенсификации теплообмена на цилиндрических поверхностях

Abstract

The assessment of thermal-hydraulic performance of certain methods of heat transfer augmentation under cross flowing by air of cylinders of different configurations was done. The comparison was made in respect of the quotient of the Nusselt number, which characterizes the heat exchange surface with intensifiers, the Nusselt number corresponding to a smooth circular cylinder, to the quotient of the corresponding Euler numbers. The results of experimental studies of the following heat transfer surfaces were considered: 1. Bundles of circular cylinders with alternating along the cylinder equal portions (length 15 mm) with different diameters (27mm and 19.6mm); 2. Circular cylinder with a protrusion with a relative height of 0.005 and 0.02; 3. Circular cylinders with asymmetric dimples with relative depth of -0.024. 4. Elliptical cylinder with dimensions of cross-section axis of 58.3 mm and 30mm. 5 . Circular cylinders with diameters of 23 mm with spiral fins with height of 10 mm and pitch of 5 mm. The advantage of forming the cylinders by asymmetrical dimples was shown.