Numerical Simulation of Flow and Heat Transfer of In-Line Tube Banks

The flow and heat transfer of the flow through in-line tube banks in a tubular heat exchanger have been numerically studied in this paper. The effects of longitudinal and transverse tube pitch ratio of in-line tube bank on the transfer characteristics of the flow pattern have been investigated quantitatively, and comprehensive heat transfer effect has been evaluated. The simulation results indicate that most of the tubes in the tube banks are affected by wake flow from the tubes in the previous column, and the structure of wake vortex is changed as a result. Compared with single tube, it is found that the capability of heat transfer is greatly improved in tube bank, and the intensification of heat transfer is more sensitive to the variation of the transversing tube pitch ratio. The results also show that both increasing the longitudinal and transversing tube pitch ratio can increase Nu. However, the resistance coefficient is inevitably increased. The tube banks with arrangements as S_L/D=2.7 and S_T/D=2.5, show the strongest overall heat transfer capability among the investigated arrangements in the present work. In addition, the relationship between St and Re is established for the investigated tube bank. The tube banks can reduce the frequency of vortex shedding compared with single tube, which indicates the vibration from the vortex shedding can be inhibited. The obtained results can provide theoretical guidance for the design of the industrial tubular heat exchanger, correct arrangement of the heated surface and the selection of the heat exchange area.