Numerical calculation is conducted to investigate the effect of structural parameters on heat transfer and flow characteristics in cross-threaded heat exchange tube with Reynolds number in the range of 415 716～ 692 861. Moreover

the dual-objective optimization method is applied to obtain the optimal solutions and related design parameters which balance the heat transfer and flow resistance. The results show that

the Nusselt number Nu and resistance coefficient f of the cross-threaded tube increases to 1.37～1.94 times and 1.75～4.70 times respectively as that of the smooth tube

and the pressure gradient and turbulence kinetic energy is enhanced due to the existence of the swirl near the wall in the cross-threaded tube

and the disturbance to the thermal boundary layer is increased

which improves the heat transfer performance of the cross-threaded tube. In addition

the Pareto front is obtained by using the genetic algorithm

and equilibrium point C of the optimal solution is given. The corresponding Nu and f are 2 161 and 0.058 8 respectively

and the design parameters are Re = 689 453

n = 6

h/di = 0.253

p/di = 0.558 8. Therefore

when making decisions based on heat transfer and flow resistance performance

if the heat transfer performance is dominant

the optimal solution is found from C～E

otherwise the optimal solution is selected from A～C.