Numerical simulation on heat transfer characteristic of conical spiral tube bundle

Conical spiral tubes are universally used in heat transfer enhancement in heat exchangers. The heat transfer characteristic of conical spiral tube bundle was investigated with numerical simulation method. Different grid strategies and boundary layers were used and the results of numerical simulation were verified via the foregoing experiment data with a tolerance less than 5%. The effect of structural parameters on heat transfer characteristic of conical spiral tube was discussed. The fluid flow characteristic inside the tube of different cross sections was also investigated. The results show that the cone angle and cross section have significant effect on tube heat transfer, while the helical pitch has little influence on heat transfer enhancement. The contours of the fluid flow inside the tube indicate that the center of the axial fluid flow offsets to the outer surface of the tube, and the secondary fluid flow is complicated. There exists four independent parts of secondary flow in each cross section and the flow directions are different from each other.