Investigation on heat transfer enhancement and velocity matching in heat exchangers by using corrugated tubes

The heat transfer and resistance performances of heat exchangers with symmetric, asymmetric, and helical corrugated tubes are investigated experimentally. Numerical simulations are conducted to examine the mechanism of thermodynamics and fluid flow. The total heat transfer efficiency of heat exchangers using these tubes is analyzed, and optimal velocity matching values are presented. The results demonstrate that the heat transfer and resistance performances of each corrugated tube on the shell side are better than those on the tube side. When compared with the symmetric corrugated tube, the large fillet radius of the asymmetric corrugated tube reduces the heat transfer and resistance performances, and the helical structure of the helical corrugated tube leads to a significant decrease in the resistance performance with a slight decrease in the heat transfer performance. The comprehensive heat transfer performance of the helical corrugated tube is better than those of other corrugated tubes by 1.5 times on the tube side and 1.67 times on the shell side. Additionally, based on the mechanism analysis, the large fillet radius of the asymmetric corrugated tube reduces the size and strength of the vortex at corrugation, while the helical flow in the helical corrugated tube significantly reduces the size of the vortex in the axial direction and extends the vortex in the radial direction. Furthermore, the maximum heat transfer efficiency and optimal velocity matching values are obtained by analyzing the total heat transfer capacity and fluid transport power of heat exchangers using the experimental tubes.