The comparable experimental investigation on the heat-exchange, resistance and fouling characteristics of normal straight tubes and twisted tubes in evaporator was carried out. The normal tube size is φ45 mm ×3 mm, the twisted tubes were consisted of the normal tubes, and the screw pitch St was 450, 550 and 650 mm. The effect of Re and St on characteristics was studied in the experiment. The results show that the fouling resistance is asymptotic within the experimental region;compared with the normal tubes, the fouling resistance of the twisted tubes is about 0.15-0.29 times and the ...