The heat-transfer characteristics of polymer hollow fiber heat exchanger were investigated by analyzing the heat-transfer coefficient (HTC) and the heat-transfer resistance (HTR) distributions of both the lumen side and the shell side. The influences of the fiber wall thickness and the polymer thermal conductivity on the heat-transfer performance were studied numerically based on the experimental validated simulation model. It is found that the original overall HTC value is below 1032 W/m(2).K and the HTR is focus on the fiber wall. However, if enhancing the polymer thermal conductivity to be higher than 1.0 W/m.K and/or lowering the fiber wall thickness to be less than 0.1 mm, the overall HTC could be improved to over 2000 W/m(2).K, which indicates that the fiber wall HTR is no longer the limiting factor of the polymer hollow fiber heat exchanger applications. (C) 2017 American Institute of Chemical Engineers