Thermo-hydraulic performance improvement of a shell-and-tube heat exchanger using perforated double-segmental baffles: A comparative CFD investigation

Abstract

This study numerically investigates the thermo-hydraulic performance of a shell-and-tube heat exchanger (STHX) with three different baffle arrangements: conventional single-segmental (CSS), perforated double-segmental (PDS), and modified geometric baffle (MGB). Three-dimensional, steady-state CFD simulations were carried out using water as the working fluid with mass flow rates varying from 0.5 to 2.0 kg/s on the shell side. The realizable k–ε turbulence model was used and the numerical model was validated against published data for a traditional single-segmental baffle heat exchanger. The results demonstrate that the perforated double-segmental baffle configuration provides the most favorable overall performance of the studied configurations. The perforated double-segmental baffle and the modified geometric baffle reduce the shell-side pressure drop by 50.85% and 37%, respectively, compared with the conventional single-segmental baffle at the mass flow rate of 2.0 kg/s. Moreover, the perforated double-segmental baffle gives the lowest friction factor, highest outlet temperature, highest heat transfer rate, and highest average Nusselt number. The perforated double-segmental baffle increases the heat transfer rate and average Nusselt number by 4.72% and 5.37% respectively compared with the conventional baffle, whereas the modified geometric baffle improves them by 3.39% and 3.85% respectively in comparison with the conventional baffle at a mass flow rate of 0.5 kg/s. The PDS configuration requires 50.85% less pumping power at 2.0 kg/s than the conventional single-segmental baffle, while also having the highest thermal effectiveness and PEC values of the configurations studied. The maximum enhancement of PEC for the PDS baffle and MGB baffle was around 33.9% and 22.9% respectively at 0.5 kg/s mass flow rate compared to CSS baffle configuration. The improved performance is attributed to enhanced shell-side mixing, smoother flow redistribution, and reduced recirculation zones caused by the perforations. Therefore, the perforated double-segmental baffle is identified as the most favorable configuration in this study based on a combined evaluation of heat-transfer rate, Nusselt number, pressure drop, pumping power, thermal effectiveness, and PEC.