关键词: 换热器, 强化传热, 螺旋弹簧, 数值模拟

Abstract: In order to investigate single-tube heat transfer enhancement principles of heat exchange tube with helical coil inserts，the flow and heat transfer characteristics were simulated using Fluent software. The effects of spring application on flow field，pressure drop and heat transfer performance were investigated. The pitch of coil spring was set as 2 mm，4 mm，5 mm. The effects of spring pitch on the heat transfer enhancement performance were analyzed. The numerical results showed that the fluid in tube with helical coil inserts presents the helical flow，the cutting speed and the radial velocity of flow near the wall had been improved to some extent. Thus the fluid was mixed completely，boundary layer was disturbed fully and heat was exchanged thoroughly. And the temperature difference between inlet and outlet increased as well, with the maximum increase of 0.9 ℃. Under the conditions of the same Reynolds number，the Nusselt number in tube with helical coil inserts was higher than plain tube，but pressure drop and friction factor increased obviously. With the reduced spring pitch, heat transfer was enhanced and friction factor was increased.

Key words: heat exchanger, heat transfer enhancement, helical coil inserts, numerical simulation