Experiment And Simulation Of Heat Transfer Enhancement In A Circular Tube Fitted With Semicircle Groove Twisted Tape

Heat transfer enhancement is one of the important branches of energy conservation research today. Recently, with the popularity and constantly updated of computer, the method of researching heat transfer enhancement has been changed from the simple experimental study to the combination of experiment and simulation method.Taking water as the working medium, this paper used experimental methods and numerical simulation methods to study the fluid flow and heat transfer of the tube fitted with semicircle groove aluminum twisted tape insert. The experimental results indicate that, the frictional resistance coefficient and the Nusselt number of the tube fitted with semicircle groove aluminum twisted tape are1%～39.5%and0.93%～21.28%greater than those of plain tube. According to the regression analysis, the correlations between the pressure drop, frictional coefficient, and Nusselt number with twist radio, groove diameter, groove pitch ratio and velocity were obtained.Through the simulation for flow field and temperature field of the twisted tube, the pressure, velocity, temperature and the heat transfer coefficient distribution in pipe were analyzed. The simulation results indicate that, there appears obvious vortex while inserting groove twisted tape. The pressure drop in the tube with semicircle groove twisted tape increases23%～58%comparing with the plain tube. The axial velocity in the zone within a radius which equal to half width of the twisted tape is smaller than that of plain tube. While the axial velocity in the zone which between the twisted tape and the tube wall is larger than the plain tube. That is advantage to thin the boundary layer. And the larger groove diameter and smaller groove pitch ratio, the greater fluid pressure drop; the smaller twist radio and groove diameter, the larger tangential velocity.Heat transfer simulation results show that the average heat transfer coefficient of the heat exchange tube with semicircle groove twisted tape is bigger than plain tube. The average surface heat transfer coefficient of the heat exchange tube with semicircle groove twisted tape is12.4%～15.3%greater than plain tube. And the larger groove diameter and smaller groove pitch ratio, the greater heat transfer coefficient.