Variable-pitch overlapped helical baffled heat exchangers were proposed and designed to improve the influence of leakage in triangle zone on the shell-side comprehensive performance.The comprehensive performance was analyzed based on numerical simulation.The results show that the main influence factors on variable-pitch helical baffled heat exchangers are helix angle combination

numbers of helix period and physical parameter of working medium.Variable-pitch helical baffled heat exchangers could improve the triangle leakage zone to some extent.Comprehensive performance of variable-pitch helical baffled heat exchanger is better than that of constant helical baffled heat exchangers with the same helix angle.When the comprehensive performance of the two kinds of helical baffled heat exchangers are the same

variable-pitch heat exchangers could enhance the heat transfer or save material of helical baffles and installing time.