Successive expansion and contraction of tubes (SECTs) in a novel design of shell-and-tube heat exchanger: a comparison between basic, finned and non-finned designs

In the present study, three-dimensional numerical simulations of turbulent flow in shell-and-tube heat exchangers (STHEs) are performed, in which a novel design of successive expansion and contraction of tubes (SECTs) is used. In these STHEs, two types of the SECT are used: (1) the SECT without fins and (2) the SECT with fins. The performance of these designs has been compared with the basic design. The study on grid independency has been done. During the validation stage, a good agreement is observed between the results and the literature. The shell-side Reynolds number has a fixed value of 20,000, while the tube-side Reynolds number has values of 5000, 8000, …, and 2000. The results show that the use of the SECT has a great effect on the effectiveness, so that its value at Re t = 5000 for the basic design and the designs including the SECT without fins and the SECT with fins is, respectively, equal to 15.7%, 22.5%, and 27.5%, corresponding to relative increases of 0, 43.3, and 75.2%. However, this design also increases the pressure drop. For example, at Re t = 5000 , the pressure drop of the SECT with/without fins is relatively increased by 1719.7%/90.2% compared to the basic design.