Experimental investigation on heat transfer enhancement of a heat exchanger with helical baffles through blockage of triangle leakage zones

The configuration of a heat exchanger with helical baffles is improved by the application of fold baffles to block the triangle leakage zones between two adjacent plain baffles. The flow patterns of shell side in the heat exchanger was numerically studied and the results showed that the helical pitch of streamlines decreases and the velocity vectors both in radial and axial directions increase obviously for the configuration improvement. The heat transfer experiments were also performed to evaluate the performance of the improved heat exchanger with fold baffles. The experimental results showed that the shell-side heat transfer coefficient α₀ and overall heat transfer coefficient K are improved by 17.7%-34.2% and 7.9%-9.7%, respectively. The increased thermal flux exceeds the pumping power penalty due to with increased shell-side pressure drop δP. And the values of thermal performance factor η_integrative are all above 1.0, which demonstrates that the better integrative performance that takes into account heat transfer coefficient and pressure drop is obtained through the configuration optimization of baffles. The conclusions are benefit to the optimizing design of heat exchanger with helical baffles for energy conservation.