The effect of shell modifications on the thermal and hydrodynamic performances of spiral tube heat exchangers

Shell and spiral tube heat exchanger configurations are vital components of industrial thermal management systems. However, the conventional heat exchanger configurations show significant limitations in terms of flow distribution and shell-side heat transfer augmentation. These limitations are major drawbacks for the heat exchanger configurations used for industrial applications where compact heat transfer equipment is required. The present numerical analysis aims to address the limitations of shell and spiral tube heat exchanger configurations by investigating two heat transfer augmentation techniques: hollowing the shell side and longitudinal baffles integrated within the shell. The novelty of this work is the combined use of heat transfer augmentation techniques, which has not been explored by other researchers who mainly used radial baffles within the shell and heat exchanger tubes. The effectiveness of longitudinal baffles within hollowed shell heat exchanger configurations is not explored by other researchers. The analysis was performed by using Ansys Workbench 2024R1 software with the k-ε model turbulence model for six different heat exchanger configurations with shell-side flow rates ranging from 2 to 6 LPM and 7000–21,000 Re while keeping the spiral tube-side flow rates constant at 3 LPM and 15,000 Re with water as the working fluid. The first modification involved an analysis of three hollowed shell diameters, with the optimal arrangement used as the basis for the second modification. Following this, three longitudinal baffle arrangements were analyzed within the hollowed shell geometry. An overall analysis of all the modified models revealed that the arrangement with four longitudinal baffles provided better thermal performance parameters with satisfactory pressure drop characteristics. Compared to the traditional model, this optimal arrangement provided significant improvements in heat transfer rate by 17.17%, overall heat transfer coefficient by 30.99%, convection heat transfer coefficient by 54.74%, and effectiveness by 14.47%.