Experimental study and numerical simulation of shell-side heat transfer and flow characteristics of a novel continuous helical baffled heat exchanger without a central tube

This study develops and evaluates a continuous helical baffle heat exchanger without a central tube to address two limitations of existing shell-side designs: leakage between discontinuous helical baffles and the occupation of shell-side core space by the central support tube in conventional continuous helical baffles. Removing the central tube retains a continuous spiral flow path and frees additional shell-side space, providing design potential for a more compact tube arrangement. Experiments were conducted to compare the proposed exchanger with a conventional segmental baffle exchanger under different operating conditions. A validated shell-side numerical model was then used to investigate helical angles from 10° to 30°. The results indicate that decreasing the helical angle strengthens circumferential motion and transverse mixing, improving heat transfer while increasing pressure drop; among the numerically investigated angles, the 10° configuration provides the best overall performance. Empirical correlations for the Nusselt number and friction factor were established for the central-tube-free structure to support engineering design. Relative to the segmental baffle exchanger, the proposed helical baffle exchanger produces a more uniform shell-side flow field, suppresses dead zones, and reaches an average performance evaluation criterion (PEC) of 1.60. For the 10° helical angle, PEC values range from 1.72 to 2.38 when the 30° case is used as the reference. The correlations ( Nu = 0.177 Re 0.584 Pr 0.333 , f = 0.532Re −0.170 ) show strong agreement with the experimental results ( R 2 > 0.99). These findings demonstrate the potential of the central-tube-free continuous helical baffle exchanger for compact and high-efficiency heat-transfer applications.