Numerical simulation was conducted on oil-water heat transfer in five circumferential overlap trisection helical baffle shell-and-tube heat exchangers (cothSTHXs) with 16 tubes and incline angles of 12 degrees, 16 degrees, 20 degrees, 24 degrees, and 28 degrees and a segmental baffle heat exchanger of the identical tube layout for comparison under laminar flow calculation conditions. The local images represent shell-side flow patterns, and heat transfer properties are presented showing the detailed secondary vortex flow and shortcut leakage flow patterns to explain the different characteristics of the six schemes. The simulation curves of the heat transfer coefficient and pressure drop are compared with those of the experimental ones, with satisfactory agreement. The average values of the shell-side heat transfer coefficient and the comprehensive index h(o)/p(o) of the 12 degrees helical scheme are respectively 47% and 51% higher than those of the segmental baffle scheme with about the same pressure drop.
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