Geometrical Optimization of Shell-and-Helical Coil Heat Exchangers for Marine Waste Heat Recovery Systems

Abstract

In maritime transportation and the facilities for ports, reliable and compact thermal components are essential for facilitating sustainable mechanical performance. The article provides a numerical evaluation of the impact of shell size on the thermal efficiency of baffled shell-and-helical coil heat exchangers (HCHEs), commonly utilized in maritime cooling, waste heat recovery, and HVAC systems on ships and offshore platforms. A verified 3D CFD model was created utilizing ANSYS Fluent to simulate steady-state fluid dynamics and thermal transport across three shell diameters (120 mm, 140 mm, and 160 mm) featuring divided baffles and a stationary helical coil. The flow rate of the cold fluid on the shell side ranged from 2 to 6 L/min. Key performance characteristics, such as heat transfer rate, thermal efficacy, and temperature distribution, were evaluated to measure thermohydraulic behavior. The model's reliability was validated by a two-stage technique utilizing experimental data and established numerical standards. The findings indicated that decreasing shell diameter markedly improves heat transmission and thermal efficiency, particularly at reduced flow rates. The compact 120 mm shell configuration frequently surpassed bigger versions, affirming the significance of structural compactness in enhancing thermal performance. These findings offer essential design recommendations for the use of compact heat exchangers into marine and port systems, facilitating advancements in sustainable and efficient maritime transportation.