Numerical simulations were carried out to investigate the heat transfer and friction loss characteristics of a circular tube equipped with helical blade rotors and to optimize the configuration of the rotor. The numerical data had good agreement with the experimental data. The simulation results revealed that for rotors with different cross section shapes, the rotor with ellipse section shape generated higher Nusselt number, friction factor and thermal performance factor than the rotor with other section shapes; for rotors with different axis diameters, the Nusselt number, friction factor and thermal performance factor increased with the increasing rotor axis diameter; for rotors with different blade numbers, the Nusselt number and thermal performance factor increased with the increasing blade number; and the rotor with four blade numbers offered the highest friction factor followed by the rotor with two blade numbers and then the rotor with three blade numbers. Meanwhile, outlet radial velocity and tangential velocity contours of the plain tube and the tube fitted with helical blade rotors were also presented in the paper, which indicated that the average radial velocity and tangential velocity of the tube with helical blade rotors were significantly larger than those of plain tube under the same Reynolds number; the rotor with ellipse section shape generated higher radial velocity and tangential velocity followed by the rotor with trapezoid section shape and then the rotor with concave section shape; both radial velocity and tangential velocity increased with the increasing axis diameter and blade number. (C) 2013 Elsevier Ltd. All rights reserved.