Morphology and Solidity Optimization of Freeform Surface Turbulators for Heat Exchangers Equipped with Narrow Channels

Improving the thermal performance of compact heat exchangers is a key challenge in the development of energy-efficient systems. This work investigates the use of topology optimization to generate novel surface geometries that enhance thermal efficiency specifically in narrow rectangular channels. A physics-based topology optimization software, ToffeeX, has been employed to explore turbulator designs within defined spatial and material constraints. The optimization process has focused on maximizing heat transfer, with particular attention on the effect of solid volumetric fraction. Simulations have been carried out using the CFD tools of the optimization software to evaluate the thermal behavior of the proposed configurations. Among the tested designs, a solid volumetric fraction of 8% has led to the most effective solution, achieving a 25% increase in outlet fluid temperature compared to a conventional ribbed reference configuration. Validation using CFD simulations with another package, OpenFOAM, has confirmed these results, showing consistent trends across methodologies. These findings highlight the potential of combining topology optimization with numerical simulation to develop advanced geometries for heat transfer enhancement. The proposed approach supports the development of more efficient and compact heat exchangers, paving the way for future experimental studies and broader industrial applications.