Simulation And Experiment Study On Heat Transfer Enhancement In Heat Exchanger Tube Inserted With Modular Twisted Tape

Heat exchanger is the key equipment to industrial heat transfer; it is an effective way for energy-saving and environmental protection by the application of heat transfer enhancement technology to improve the heat transfer performance. The heat exchanger tube with self-rotating twisted tape can not only enhance heat transfer, but also play the role in preventing fouling on-line.Simulation and experiment investigation was carried for heat transfer enhancement in the heat exchanger tube with modular twisted tape inserted which taking water as the working fluid, and comparing analysis with perforated twisted tape and plain tube. The experimental results show that:the pressure drop, coefficient of heat transfer and Nusselt number of the tube with modular twisted tape inserted are all improved. Among them, the pressure drop of the tube with twisted tape increase 23.2%～37.9% than the plain tube; the coefficient of heat transfer of the tube with twisted tape average increase 16.39%38.88% than the plain tube, the tube with modular twisted tape average increase 19.49% than the tube with perforated twisted tape; the Nusselt number of the tube with twisted tape average increase 13.01%～20.38% than the plain tube, the tube with modular twisted tape average increase 6.52% than the tube with perforated twisted tape. The comprehensive performance evaluation 0 for the heat exchange tube with modular twisted tape inserted is greater than 1, and the maximum Φ reaches 1.16. That shows the enhanced heat transfer is implemented effective of when the tube fitted with modular twisted tape.The numerical simulation results show that:the fluid is a three-dimensional spiral trajectory flow in the tube with modular twisted tape, and the boundary layer fluid velocity is greater than plain tube and the tube with perforated twisted tape, which increase 5.03%～16.68% than the plain tube and increase 1.20%～3.37% than the tube with perforated twisted tape. It is thinning the thickness of boundary layer fluid in tube. The three-dimensional spiral flow, secondary flow and the increase in the boundary layer velocity are the main causes heat transfer enhancement of the heat exchange tube. The heat transfer coefficient of tube with modular twisted tape increases with decreasing width, twisted radio and staggered radio of twisted tape, and the changing of the heat transfer coefficient on inner surface shows decreasing trend from the inlet to the outlet. The temperature distribution of heat exchange tube wall is logarithm distribution with the pipe wall radius, and the temperature value decrease from outside to inside gradually.