Presented in this paper are experimental test and comparison for several shell-and-tube heat exchangers, one with segmental baffles and four with helical baffles at helix angles of 20 degrees, 30 degrees, 40 degrees and 50 degrees, respectively. The results show that, based on the same shell-side flow rate, the heat transfer coefficient of the heat exchanger with helical baffles is lower than that of the heat exchanger with segmental baffles while the shell-side pressured drop of the former is even much lower than that of the later. Further enhancement techniques should be incorporated in order to enhance shell-side heat transfer based on the same flow rate. The comparison of heat transfer coefficient per unit pressure-drop (and pumping power) versus shell-side volume flow rate shows that (1) the heat exchanger with helical baffles have significant performance advantage over the heat exchanger with segmental baffles; (2) for the same shell inner diameter, the performance of heat exchanger with helical baffles with 30 degrees helix angle is better than that of 20 degrees, and the performance of 40 degrees, helix angle is better than that of 50 degrees helix angle. The heat exchanger with helical baffles of 40 degrees angle shows the best performance among the five heat exchangers tested. (C) 2009 Elsevier Ltd. All rights reserved.