Numerical simulation for heat transfer enhancement of a heat exchanger with helical baffles

Four plain baffles are currently used to form a helical pitch in helical baffle heat exchangers, which degrades heat transfer performance of heat exchanger obviously. A new structure of ladder-type fold baffle is proposed to block the triangular leakage zones between two adjacent plain baffles, which forces the shell-side fluid to move in an approximately continuous spiral flow. Numerical simulation results show that there is a significant increase in tangential and radial velocity of the shell-side fluid, but the axial velocity is slightly lower in the improved heat exchanger with ladder-type fold baffles. The overall heat transfer coefficient of the improved heat exchanger increases by 51.7%-66.1% and the shell-side pressure drop increases by 159.8%-186.2%. The thermal performance factor TEF enhances by 10.4%-17.0%, with an average increase of 14.1%. The ladder-type fold baffles can effectively improve the heat transfer performance of helical baffle heat exchangers, and are convenient to locate and install.