Optimal design of helical heat/mass exchangers under laminar flow: CFD investigation and correlations for maximal transfer efficiency and process intensification performances

摘要

Highly curved helical pipes (HCHPs) offer tremendous potentialities for intensified heat/mass transfer performances as they generate intense Dean-type vortices. However, these designs have not been explored so far in the literature, probably because they are difficult to build using traditional manufacturing techniques. Nowadays, thanks to a witnessed progress in 3D-printing, the fabrication of HCHPs has become achievable. Therefore, investigating their performance in terms of heat and mass transfer intensification presents significant interest from both academic and industrial points of view. In this paper, CFD simulations are carried out to determine the heat/mass transfer efficiency in helical pipes (particularly highly curved ones) under laminar flow conditions. The packing density (i.e. interfacial area) of these geometries is evaluated using a CAD software. The results reveal that HCHPs not only allow achieving much higher transfer rates than straight and classical helical pipes, but they can also be densely packed. Therefore, when appropriate designs are selected, impressive process intensification factors are achievable, with up to 8-fold volume reductions. Finally, correlations are developed for evaluating the interfacial area and the heat/mass transfer efficiency in classical and highly curved helical pipes. In future works, these correlations will be used in model-based optimization for determining the optimal designs of helically coiled heat/mass exchangers.