An experimental heat transfer study for helically flowing outside petal-shaped finned tubes with different geometrical parameters

The performances of shell-side heat transfer and pressure drop were experimentally studied in a helically baffled single tube heat exchanger, where water was used as a working medium. The tested tubes included one smooth tube and five petal-shaped fin tubes (PF tubes) with different geometrical parameters for improving the heat transfer of the shell side. It was shown that, compared with the smooth tube, five PF tubes significantly increased the values of Nusselt numbers. The Nusselt numbers increased with the fin height and decreased with the fin pitch. In the range of the present experiments, it was found that the Nusselt numbers for the PF tubes were increased by up to 233%, while the pressure drop was increased by less than 111%, as compared with that for the smooth tube. It is a promising route to use a PF tube instead of smooth tube for improving the performance of a helically baffled heat exchanger.