Multiple longitudinal vortex was made in a tube by double-twist elements incorporated in a section. Longitudinal vortex form and strength were affected by two adjacent twist elements rotate direction and dislocation angle. The effect of dislocation angle on Nusselt number and pressure drop was more significant than on the elements rotate direction. To study the influence of different combinations of twisted element on turbulent heat exchange performance

the coordination between velocity

temperature gradient and pressure gradient were studied using six different combinations of twisted element in a section. The results show that in the near wall region

increasing dislocation angle can improve the coordination between velocity and temperature gradient and two adjacent twist elements in opposite rotate direction are better than that in the same each other. For the coordination between velocity and pressure gradient

two adjacent twist elements in the same rotate direction are superior to that in opposite each other

but the difference decreases with the increasing dislocation angle. When the dislocation angle is 90°

the difference is minimal in the range of y/R < 0.75.