Simulation Of Fluid Flow And Heat Exchang In A Helical Tube Under Constant Wall Temperature Condition

Spiral tube can be used as the basic structure of the wound tube heat exchange. It can be also used alone as a heat high efficiency exchanger. With the advantages of high efficiency, is widely used in petroleum chemical industry?refrigeration and other fields. The spiral tube as an efficient heat transfer equipment, has been the focus of attention in the field of heat transfer enhancement. The research for spiral pipe is mainly focused in the circular cross section, on the fluid flow and heat transfer performance of rectangular section spiral tube, there are few reports, also from the field synergy angle analysis of spiral tube enhanced heat transfer mechanism of also do not see more.This paper summarizes research situation at home and abroad of the spiral pipe and simply introduce heat transfer enhancement technology and field synergy theory. On the basis of previous frameworks, numerical method is used to establish three-dimensional spiral tube physical and mathematical model. According to Fluent software workflow, respectively calculate the flow and heat transfer of fluid in laminar and turbulent in circular cross section and rectangle section spiral tube under the constant wall temperature condition, using average nusselt number Nu of fluid in a tube and pressure drop loss ?P of import and export to evaluate these two section of spiral tube heat transfer and flow resistance performance under different geometry parameters. Reference comprehensive performance evaluation factors to make comparative analysis of the influence of fluid average velocity v, the tube pitch P, screw diameter D and cross-sectional area on heat transfer enhancement and flow resistance and heat transfer performance of two section spiral tube. Considering the equal cross-sectional area, the change of rectangular cross section shape has influences on fluid flow, heat transfer tube and enhancement of transfer performance. From the Angle of field synergy, make some comparison and analysis on the inner mechanism of two kinds of cross section heat transfer enhancement spiral tube. According to the angle between the velocity field and temperature field, it analyzes the changing rule of collaborative performance with pitch, screw diameter, and cross-sectional area of two section spiral pipe flow.Results show that two section spiral tube in fluid under laminar flow and turbulent flow are secondary flow phenomena,near the entrance, secondary flow of fluid in the pipe could be ignored, as the angle increasing, secondary flow effect is strengthening, and affected by the cross-section shape and fluid flow of spiral tube. The velocity of fluid and the temperature of the spiral tube will show different distribution shape. As the two section spiral tube geometric parameters change, the Nu??P and ? of the fluid in the spiral tube will present different variation. The performance of flow resistance, heat transfer, enhanced heat transfer circular cross section spiral pipe flow resistance, heat transfer, enhanced heat transfer performance were better than that of the rectangular section. The equal section area, wide flat rectangular section of enhanced heat transfer performance is better than high narrow section. The angle of velocity field and temperature field with the spiral tube geometric parameters and the fluid flow and heat transfer of the changes are basically consistent, indicating that the field synergy theory can explain spiral tube heat transfer enhancement with the inherent mechanism of the variation of geometric parameters.