Bidirectional heat transfer enhancement is of great importance for simultaneously enhancing the heat transfer in the tube side and shell side. In this paper, an extruded tube with dimples and protrusions (EXTDP) is proposed, and the thermo-hydraulic performance is analyzed numerically. The various dimpled tubes are compared to demonstrate the heat transfer enhancement mechanism. In addition, the effects of structure parameters are discussed at Reynolds numbers (Re) ranging from 10000 to 30000. The numerical results reveal that the structure of dimples and protrusions improves the fluid mixing and disruption of boundary layer flow. The smooth transition surface decreases the flow resistance inside the EXTDP. In addition, the large deformation of tube walls increases the disturbance of the external flow in a broader range, which improves heat transfer performance for the external flow. The Performance Evaluation Criteria (PEC) of internal and external flow are increased by up to 1.46 times and 1.36 times, respectively. Furthermore, the PEC is improved with the rising dimple depth and the decline of dimple pitch. The present study provides valuable guidance for the design and application of enhanced tubes.
He et al. (Wed,) studied this question.