Augmentation of convective heat transfer of highly viscous fluid within three-dimensional internally finned tube

摘要

Investigation on the heat transfer and friction characters for fresh oil flowing inside three-dimensional internally finned tube (3-DIFT) was carried out with orthogonal experimental design method. Reynolds numbers varied from 30 to 800, Prandtl numbers 550 to 1000. The experimental results showed that low critical Reynolds numbers at the range of 100 to 200 were attained within all the experimental tubes, which indicated that 3-DIFT could obvious accelerate the transformation of high viscous fluid from laminar flow to turbulent flow. It offered a particular advantage to enhance the convective heat transfer of highly viscous fluid. Empirical equations on flow resistance and heat transfer were obtained using a least-squares regression. Compared with empty smooth tube, the maximal thermal performance factor for the turbulent flow within 3-DIFT could be enhanced up to 3.61. The optimization on shape of 3-DIFT for further augmentation heat transfer was also obtained.