Application of rough surfaces to heat exchanger design
International Journal of Heat and Mass Transfer, 15 (9):
1647 - 1658 (1972)DOI: 10.1016/0017-9310(72)90095-6
Abstract
Equations are developed to define the performance advantage of roughened tubes in heat exchanger design, relative to smooth tubes of equal diameter. Three rough tube applications are presented: 1. To obtain increased heat exchange capacity; 2. To reduce the friction power; and 3. To permit a reduction of heat-transfer surface area. A heat exchanger design procedure is developed for each application and is based on the use of previously developed generalized heat transfer and friction correlations for rough surfaces. The graphical results of example solutions are presented for the case of “repeated-rib” roughness. These graphs show the heat exchanger performance improvements offered by this roughness type, relative to smooth tubes. Because the heat transfer and friction correlations used for the “repeated-rib” roughness can be used to correlate the data of other types of geometrically similar roughness, the design procedure is applicable to other types of roughness. In addition to flow thru tubes, the design procedure and the calculated results are equally applicable to the problem of parallel flow along the outside surfaces of tubes arranged in a tube or rod bundle.