Characterization of the effect of corrugation angles on hydrodynamic and heat transfer performance of four-start spiral tubes

A series of four-start spirally corrugated tubes has been subjected to heat transfer and hydrodynamic testing in a double-pipe heat exchanger. The stu dy has been focused on the non-symmetric nature of the corrugation angles a long the longitudinal direction. Both friction factors and heat transfer co efficients inside the tubes ha ve been correlated against various process p arameters. It can be shown that by altering the internal non-symmetric wavy shapes of the tubes, one is able to manipulate heat transfer and friction characteristics. The experimental results have been compared with some popu lar correlation models developed previously for both friction and heat tran sfer for corrugated tubes. Considerable differences between the experimenta l results and the predictions made using the existing correlations have bee n found and the probable causes have been discussed. Performance evaluation criteria are presented using the standard constant power criterion. A neur al network modeling approach has been taken so that, based on the limited d ata, one can generate. the contour showing the effect of corrugation angle on heat transfer coefficient for geometry optimization purposes.