Numerical simulation of heat transfer and resistance characteristics of the restricted outgoing flow in a spiral channel

Through a three-dimensional numerical simulation, a study was conducted of the heat transfer and flow characteristics of restricted outgoing flows inside a spiral channel with different spiral angles (15°, 20°, 30°, 40°, 45°, 50°, 60°). The authors have proposed several optimization modes applicable in a certain range of Reynolds Number (0.8 × 10⁴≤Re≤6 × 10⁴), thereby improving the flow conditions and heat transfer at the shell side of a tube-and-shell type heat exchanger. The results of the study show that the restricted outgoing flow in the spiral channel can form an ideal plunger flow with the velocity distribution inside the channel being uniform, thus effectively minimizing and eliminating flow dead areas. Compared with a 'Z'-shaped restricted outgoing flow formed by vertical baffles, the above-mentioned flow inside the spiral channel can boast a relatively high heat transfer coefficient and enjoy an obvious energy-saving effectiveness at a same pressure-drop gradient. In the range of Reynolds number under investigation, the flow in question has a comprehensive performance of optimum heat transfer and resistance when the spiral angle a is around 45°. The research findings can well provide a theoretical basis for the design of a high-efficiency and low-resistance structure at the shell side of a shell-and-tube type heat exchanger and for its further optimization.