Investigations of thermo-hydraulic performance were conducted on five trisection helical baffle heat exchangers with different inclination angles, baffle shapes, or connection patterns, and one segmental baffle heat exchanger (SEG). A comparative analysis of three sector baffle schemes with inclination angles of 10 degrees (10 degrees S),15 degrees (15 degrees S), and 20 degrees (20 degrees S); an ellipse baffle scheme with an inclination angle of 15 degrees (15 degrees E); and an axial overlap sector baffle scheme with an inclination angle of 20 degrees (20 degrees D) was performed. Local images were constructed to obtain pressure loss characteristics and flow field distributions. The flow field characteristics, such as the Dean vortex secondary flow and bypass leakage between adjacent baffles, are clearly shown and discussed. The same inclination angle schemes have completely different properties because of the baffle shapes or connection patterns. The performance of the end-to-end scheme is superior to that of the axial overlap scheme, and the ellipse baffle scheme is inferior-to the sector baffle scheme. The 20 degrees S scheme has the optimum comprehensive index and lowest shell-side pressure loss. The 10 degrees S scheme has the highest shell-side Nusselt number and shell-side pressure loss, and can be selected only when heat transfer capability is very important in an engineering application. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.