Pilot experimental study on shell and tube heat exchangers with small-angles helical baffles

In this paper, the experimental comparisons of shell side thermodynamic and hydraulics performance are made among three helical baffles heat exchangers and one segmental baffles heat exchanger. The experiment scale is larger than the previous experimental setup as the diameter of test heat exchangers are 500 mm and the effective tube length are 6 m; the experiment mainly focuses on the small helical angle scheme as the helical angle ranges from 7° to 25°. Among all the four heat exchangers, both the shell side heat transfer rate and the shell side pressure drop peak when helical angle equals 7°, and the shell side heat transfer rate per unit pressure drop at this angle is the smallest. This phenomenon could be easily illustrated as the concept ‘fluid-flow distance’ is presented. At last, the correlations for the shell side Nusselt number and friction factor are presented as a reference.