Investigation of heat transfer performance and flow characteristic in helically coiled-twisted flat tube

Heat transfer performance and flow characteristics in the Helically Coiled-Twisted Flat Tube (HCTFT) are studied by a numerical simulation. According to the results, the secondary flow caused by the twisted structure destroys the velocity boundary layer, decreases the thermal-conduction resistance, increase the turbulence kinetic energy. The heat transfer performance of HCTFT is greater than Helically Coiled Smooth Tube (HCST). In the range of research, the Performance Evaluation Criterion (PEC) could achieve the maximum value 1.21, 1.21, 1.35 and 1.23, respectively. New correlations of heat transfer performance and flow characteristics in the tube side are developed.